HomeMy WebLinkAboutMeeting Packet - Water Resources - 9/19/2011
WATER RESOURCES ADVISORY BOARD MEETING
Monday, 19 September 2011
7:00 p.m.
13th Street Conference Room
1720 13th Street
Agenda Highlights:
I. Call to order. (7:00 p.m.)
II. Approval of minutes from the 15 August 2011 meeting (7:01 p.m.)
III. * Public Comment Period. (7:10 p.m.)
IV. Matters from Board/Staff. (7:15 p.m.)
V. *Discussion about the Fort Collins 2003 study effort on fluoride in drinking water (7:30
p.m.)
VI. Discussion about Future Schedule (8:30 p.m.)
VII. Adjournment. (8:35 p.m.)
* Public Comment Item
Information: Contact the WRAB Secretary, Laurel Olsen-Horen at (303) 441-3203 or
olsenlnbouldercolorado.gov. . Packets are available in the reference section of the Main
Library and on-line at http://Nvww.bouldercolorado.gov, Departments, Public Works,
Utilities, Water Resources Advisory Board. Agenda item times are approximate.
WRAB
On-going Calendar, Regular Agenda Items
Revised 09-12-2011
September 19, 2011 (Scharnhorst gone)
- Discussion about the Ft. Collins 2003 study effort on fluoride in drinking water (Williams)
October 17, 2011
- Tentative, Recommendation on MOU with CU about Recirculation of Wastewater (Williams,
Ellinghouse, Douglas)
- Tentative, Update on Boating on Barker Reservoir Proposal (Linenfelser)
November 21, 2011
- Update on Boulder Reservoir Master Plan (Linenfelser, Wind, Parks and Recreation staff)
- Tentative, Update on status of Commercial, Industrial and Institutional (CII) Water Budget Options
(Linenfelser, Sands)
December 19, 2011
- Reschedule Jan. 16, 2012 and Feb. 20, 2012 meetings
- Tentative, Energy Efficiencies and Usage (Crittenden, Douville, Gallo and Castro)
- Tentative, Revenue Stabilization (Baird)
- Tentative, Update on South Boulder Creek Flood Mitigation Study (or, 1St quarter 2012)(Bauer,
Harberg)
January 16, 2012 (Holiday, need to reschedule meeting date)
- Tentative, Update on Fluoride in drinking water (Crittenden, Linenfelser)
- Tentative, Update on Low Impact Development for Stormwater (Harberg, Arthur, Linenfelser, Gallo)
- Tentative, Update on Carter Lake Pipeline CEAP (Taddeucci, Harberg)
February 20, 2012 (Holiday, need to reschedule meeting date)
- Tentative, Update on Financial (Rates, bonds and reserves) (Baird, Harberg)
March 19, 2012 (Last meeting for Bill DeOreo)
- Tentative, Update on Technology & Benchmarks (Crittenden, Douville, Crean, Harberg, Gallo)
- Tentative, Update on Water Rights for the Xcel Energy Valmont Plant (Hutton)
April 16, 2012 (Initial meeting for new member who may be appointed March 20)
- Election of WRAB officers
- Update and discussion of 2013 Utilities Budget, including CIP and rates
- Turn Page Over -
- Tentative, Update on Instream Flow Programs (Hutton)
May 21, 2012
- Update and discussion of 2013 Utilities Budget, including CIP and rates
- Tentative, Update on Source Water protection and enhancement (Linenfelser)
June 18, 2012
- Recommendation on 2013 Utilities Budget, including CIP and rates
July 16, 2012
August 20, 2012
- Tentative, Update on Federal and State regulations for wastewater (Douville, Linenfelser)
September 17, 2012
October 22, 2012
November 19, 2012
December 17, 2012
WRAB calendar ongoing
- Turn Page Over -
CITY OF BOULDER, COLORADO
BOARDS AND COMMISSIONS MEETING MINUTES
Name of Board / Commission: Water Resources Advisory Board
Date of Meeting: 15 August 2011
Contact Information of Person Preparing Minutes: Laurel Olsen-Horen; 303-441-3203
Board Members Present: Bill DeOreo, Chuck Howe, Kate Ryan (arrived at 7:10), Vicki Scharnhorst
Board Members Absent: Susan Iott
Staff Present: Ned Williams, Director of Public Works for Utilities
Bob Harberg, Engineering Project Management Coordinator
Bret Linenfelser, Water Quality Coordinator
Joe Taddeucci, Project Manager
Carol Ellinghouse, Temporary Administrative Specialist
Kathy Haddock, Senior Assistant, City Attorney's Office
Laurel Olsen-Horen, Board Secretary
Meeting Type: Regular
Agenda Item 1- Call to Order [7:05 p.m.]
This meeting was called to order at 7:05 p.m.
Agenda Item 2 - Approval of the 9 July Retreat minutes and the 18 July Meeting Minutes:
The Retreat minutes were approved as presented. Moved by: Scharnhorst, seconded by Howe.
Vote: 3:0
The 18 July meeting minutes were approved as presented; moved by: DeOreo, seconded by Scharnhorst.
Vote: 3:0
Agenda Item 3 - Public Participation and Comment [7:08 p.m.]
Public Comment:
none
Agenda Item 4 - Matters from Board and Staff [7:08 p.m.]
Board member Ryan arrived at 7:10
Matters from Board:
Board member Howe brought up the below matters:
• The MOU with CU. There were questions on the economic and environmental assessment and the
water monitoring program. CU (Professor JOArm Silverstein) has submitted a proposal that
addresses the questions the board had at the July meeting. She will hopefully be able to bring the
full report back to the WRAB by December. Howe wishes to propose that the Board accept their
proposal as our study of that system. Howe believes the board should encourage CU to proceed
with their research.
• Non-motorized boating on Barker Reservoir. This issue has been looked into for about ten years.
There is sufficient research to propose non-motorized boating program on Barker Reservoir.
Board member Scharnhorst brought up the below matters:
• Scharnhorst attended the August 10,h meeting hosted by the City Manager on Boulder's Energy
Future. There was a very nice review and discussion for the participants. (handed out a couple of
flyers from that meeting)
Board member Ryan
• Ryan gave an update on her attempts to communicate with the Water Board in Fort Collins
Matters from Staff:
Williams brought up the below matters:
• There will be a meeting for WRAB members to attend a meeting with the finalists for the Director
of Public Works for Utilities. It would be great if the board members can attend part or all of that
day. Williams asked for each board member to him a brief biography to submit for the finalists of
the Utilities Director position.
• The 2012 City budget; there was a Study Session last week with Council. The manager's proposed
budget will be delivered in September. There will be a Study Session on 13 September for the
proposed budget, which will likely include a 3% increase in each of the three utilities.
• The city began some construction projects; 75th WWTP to convert and install the ultraviolet
disinfection, along with some head works upgrades and improvements to the digester mixing.
There are also some pipeline replacement projects going on around the city.
WRAB Minutes
15 August 2011
Page No. 1
Agenda Item 5 - Recommendation on revisions to B.R.C. 11-1-19, Water and Ditch Rights
[7:48 p.m.]
Ned Williams, Kathy Haddock and Carol Ellinghouse presented item to the board.
Executive Summary from Packet Materials:
The Water Resources Advisory Board (WRAB) is asked to make a recommendation to City Council
regarding amendments to Section 11-1-19 of the Boulder Revised Code (B.R.C.) 1981, entitled "Water and
Ditch Rights." Section 11-1-19 describes the city's acquisition of water and ditch rights when an applicant
annexes into the city and/or requests a permit to connect to the city's water main. These conditions allow
the city to acquire water supplies to offset the water needed by the new or expanded use.
The City Council passed Ordinance No. 7763 on first reading on October 19, 2010, (see Attachment A,
then internal Attachment A). After passing the ordinance, Mayor Osborne asked that the ordinance be
referred to WRAB for a recommendation before coming back to council. WRAB provided continents (see
Attachment C, then internal Agenda Item 6) on the ordinance at its meeting on January 20, 2011 and
agreed that a substitute ordinance should be prepared. Staff has prepared a proposed substitute ordinance
(see Attachment B) based on the WRAB's comments and feedback.
Public Comment: [8:01 p.m.]
Catherine Long-Gates: First off. Ms. Long-Gates appreciates the efforts of staff to produce a new
ordinance, especially the last part, and would like to ask the board to take into consideration the ability to
transfer their shares to another ditch user. There is value of keeping other types of users on any given ditch,
not just the city (which falls under the majority share holder in a few cases)
Judith Renfroe: Why didn't the exceptions include RR2 lots as those lots are larger than 15k ft2? Ms.
Renfroe would also like to encourage the board to allow for the transfer of ditch shares to fellow ditch
users. The majority of Ms. Renfroe's ditch is owned by Xcel Energy. They were proposing to change the
by-laws stating that the ditch users would have to offer a first Right of Refusal to Xcel: that would create a
predicament between the ditch users and the city.
WRAB discussion included: [8:10 p.m.]
• With this new ordinance, would ditch users be allowed to sell their water rights to another ditch
user; how would this current ordinance cause any issues? Staff response: this ordinance would not
restrict that type of sale when an owner is not annexing or requesting a water tap permit; however
the purchaser may encounter some outdoor water budget reductions as a result of buying new
ditch water rights since the purchaser would not need to depend as much on city treated water.
• Given that water is a property right, why does the city make a distinction between properties in the
city and those that are being annexed into the city? Staff response: The water is purchased at fair
market value at the time of annexation or development and is not "exacted"- at no cost to the city,
from the property owner. At time of annexation or development, the city has all property owners
go through the processes to ensure that proper right-of-way and easement acquisitions are made.
When approached by a property owner, the city reviews each situation on a case by case basis.
• Whether to include right of first refusal conditions and how it is preferable to use the special
agreement section to deal with unique situations.
Motion: Moved by Scharnhorst; Seconded by Ryan: Move to accept an ordinance repealing and re-
enacting section 11-1-19, "Water and Ditch Rights", B.R.C. 1981, to address agreements for right of
first refusal, purchase and sale of water or ditch rights, and resulting adjustment of water budget;
eliminate references in the code to Silver Lake Ditch and setting forth related details; with the one
edit in paragraph B to make a reference to the Plant Investment Fee.
Vote: 4:0 - motion passes (Howe abstains which, by B.R.C. 2-3-1(f) is recorded as an affirmative vote)
Agenda Item 6 - Discussion about agenda item priorities for future schedule [8:40 p.m.]
Ned Williams presented item to the board.
Executive Summary from Packet Materials:
At the Water Resources Advisory Board (WRAB) retreat on July 9, 2011, a list of "Challenges for the
Future in Water, Wastewater and Stormwater/Flood Management Utilities" was developed and discussed.
WRAB Minutes
15 August 2011
Page No. 2
A consolidated spreadsheet (see Attachment A) was subsequently put together and each WRAB member,
along with city staff, has been asked to identify the 8-10 items of highest priority.
At the Aug. 15 WRAB meeting, WRAB will review the results of each member's and staff s ranking and
reach agreement on the 8-10 items that should be calendared in the next 12-18 months as agenda items.
WRAB discussion included: [8:45 p.m.]
• There isn't any wastewater issues on the future agenda currently, WRAB would like to make sure
the wastewater side of things isn't forgotten.
• Items that scored 3 or more votes were selected; combined #1 and #11, added 421.
Final list of highest priority items are:
1. What is Boulder's Energy Future and how to integrate with water, wastewater and stormwater /
flood management, including energy efficiencies and energy usage at facilities
2. What is Boulder's Energy Future and how to integrate with water, wastewater and stormwater /
flood management, including energy efficiencies and energy usage at facilities
3. Fluoride in drinking water (after the US Health & Human Services guidelines are released)
4. Use more low-impact development (LID) methods to improve stormwater quality(i.e.,
Philadelphia, Kansas City)
5. Financial - keep rates at a sustainable level: pay-as-you-go vs. borrow; adequate financial reserves:
funding for high-cost capital projects (i.e., treatment plant upgrades, Carter Lake Pipeline, South
Boulder Creek Flood Mitigation or Hydroelectric projects)
6. Technology and staff - Supervisory Control and Data Acquisition (SCADA) systems (how to
improve and use for more efficient management and control); succession planning, knowledge
transfer, training and promotional opportunities, update on Peer Review report and Front-Range
community survey, Benchmarking data (more background information on staffing levels)
7. Xcel Energy / Valmont power plant - certainty and schedule for closing (2017?) the plant, and
whether or not to acquire the water.
8. Instream flows (Boulder Creek, South Boulder Creek, Colorado River, South Platte River, etc.)
9. Source water protection and enhancement to deal with: emerging contaminants, endocrine
disrupting chemicals and pharmaceuticals/personal care products, Aquatic Nuisance Species,
Mountain Pine (Bark) Beetle and forest fires
10. Federal and state regulations for wastewater discharge, WWTF discharge permit, total maximum
daily loads (TMDLs) and nutrient criteria
Next Steps: Williams will work with staff over the next couple of months to get theses items on the agenda
for future WRAB meetings.
Agenda Item 7 - Discussion about the 'L'ater Utility Master Plan [8:47 p.m.]
Bob Harberg and Joe Taddeucci presented item to the board
Executive Summary from Packet Materials:
While the Water Resources Advisory Board accepted the Water Utility Master Plan (WUMP) at its May
16, 2011 meeting, the WRAB also requested a meeting to further discuss some of the assumptions and
details contained in the WUMP.
The 'YNTUMP is a comprehensive analysis and plan for the city's water source, storage, treatment and
delivery systems and is intended to guide future water utility decisions. The plan updates the 10-year-old
Treated Water Master Plan and general planning information and population projections. It also
incorporates the recently completed Source Water Master Plan (2009) and Water Quality Strategic Plan
(2009) and consolidates and prioritizes capital improvements in the Source Water, Water Quality and
Treated Water plans. The WUMP pulls together all of the previously separate master plans for different
aspects of the city's Water Utility. Completion of the WUMP represents a major planning milestone for
the Utilities Division.
The plan has the following components:
• Volume 1 - Executive Summary
• Volume 2 - General Planning Information
• Volume 3 - Water Quality Strategic Plan (2009)
• Volume 4 - Source Water Master Plan (SWMP) (2009)
WRAB Minutes
15 August 2011
Page No. 3
• Volume 5 - Treated Water Master Plan (TAATMP)
• Volume 6 - Consolidated Capital Improvements Plan
WRAB discussion included:
The board members discussed further details of the revised volumes presented in the packet materials. A
few editorial comments were made during this discussion and several errors to data/tables were pointed out.
Agenda Item 8 - Discussion on Future Schedule [9:15 p.m.]
Special meeting on 25 August to participate in the selection process for the Utilities Director
Agenda Item 9 -Adjournment [9:22 p.m.]
There being no further business to come before the Board at this time, by motion regularly adopted, the
meeting was adjourned at 9:22 p.m.
Date, Time, and Location of Next Meeting:
The next regular WRAB meeting will be 19 September at 7:00 p.m., at the 13`h Street Conference Room
located at 1720 13'h Street, unless otherwise decided by staff and the Board.
APPROVED BY: ATTESTED BY:
Board Chair Board Secretary
Date Date
An audio recording of the full meeting for which these minutes are a summary is available on the Water
Resources Advisory Board web page.
WRAB Minutes
15 August 2011
Page No. 4
C1 ~ . • C
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pF BoJ
CITY OF BOULDER
WATER RESOURCES ADVISORY BOARD
MEETING DATE: September 19, 2011
AGENDA TITLE
Discussion about the City of Fort Collins' 2003 study effort on fluoride in drinking water
PRESENTERS
Ned Williams, Director of Public Works for Utilities
Bret Linenfelser, Coordinator of Water Quality and Environmental Services
Bob Harberg, Coordinator of Planning and Project Management
EXECUTIVE SUMMARY
The Water Resources Advisory Board (WRAB) has identified "Fluoride in Drinking Water" as a
challenge and priority for the fiiture and plan to discuss this topic after the U.S. Department of
Health and Human Services issues its final guidance on fluoride level. As background
information, WRAB members are interested in the process and results from the City of Fort
Collins, CO effort. A summary of the Fort Collins effort is as follows:
1954- Ballot issue to fluoridate water fails
1967- Ballot issue to fluoridate water passes and Fort Collins begins to add fluoride to
the water supply
2001-2002- The Fort Collins Fluoride Technical Study Group (FTSG) is organized and meets
monthly between Dec. 2001 and Nov. 2002
April 2003 - Report of the Fort Collins Fluoride Technical Study Group (Attachment A,
approximately 80 pages) released (a copy will be mailed to WRAB members)
May 2003 - Fort Collins City Council reviews the Report of the Fort Collins Fluoride
Technical Study Grorrp and considers the recommendations from the Fort Collins
Water Board, Larimer County Board of Health and the Health District of
Northern Larimer County
July 2003 - City Council votes (4-3) to continue the city's fluoridation program
Dec 2004 - City Council places a citizen-initiative issue about fluoride on the next ballot
April 2005 - Ballot issue to discontinue adding fluoride to the city's water supplies fails
(For-10,501; Against-20,626)
Page 1
BACKGROUND ABOUT BOi1LDER
In 1969, Boulder voters approved the addition of fluoride to the city's drinking water to
reduce tooth decay. The ballot language stated that the city would introduce fluoride into
the water supply to maintain a concentration of approximately one part offluoride
to one million parts of ivater." At that time, the fluoridation of drinking water was
endorsed by various health organizations (such as the United States Public Heath Service,
the American Public Health Association, the American Dental Association and the
American Medical Association) and various local civic groups and organizations. Since
1969, the city has added fluoride to its drinking water in sufficient quantities to meet the
recommendations of the various health organizations as well as the requirements of the
approved ballot language. The city currently adds fluoride to maintain a concentration of
09 parts per million, as recommended by the Colorado Department of Public Health and
Environment (CDPHE).
In 2006, a local ballot measure initiated by voters included eliminating fluoridation of
drinking water. It failed (For- 48.2%; Against- 51.8%).
On Jan. 7, 2011, the U.S. Department of Health and Human Services (U.S. HHS) and the
U.S. Environmental Protection Agency (EPA) jointly announced important steps to
ensure that people benefit from tooth decay prevention while at the same time avoid the
unwanted effects from too much fluoride. While the U.S. HHS provides a recommended
"optimal level" for fluoridation, it is not the regulatory agency for drinking water
standards. Rather, the EPA regulates maximum levels of fluoridation allowed in drinking
water. The U.S. HHS proposed that the optimal fluoride level be reset to 0.7 parts per million,
which is lower than the previous recommended level which ranged from 0.7 to 1.2
parts per million. While the HHS was expected to issue final guidance on the optimal level of
fluoride this spring or summer, it is unknown when the final guidance will be released.
The EPA will initiate a review of the current maximum amount of fluoride allowed in
drinking water and determine whether the drinking water regulations should be revised.
Currently, the maximum amount of fluoride in drinking water is not to exceed 4.0 parts
per million as regulated by the Safe Drinking Water Act. However, the EPA has a non-
enforceable secondary standard of 2.0 parts per million. This means that utilities should not
exceed 2.0 parts per million of fluoride in drinking water, but regulatory enforcement doesn't
occur until the maximum 4.0 parts per million is reached. The schedule for the EPA review of its
fluoride regulatory levels is not known.
If the final guidance from the U.S. HHS is that 0.7 parts per million of fluoride is an
optimal level and the CDPHE supports the recommendation, the city is planning to reduce the
amount of fluoride added to Boulder's drinking water to maintain a concentration of 0.7 parts per
million. This approach is consistent with the legislative intent of the 1969 ballot measure.
ATTACHMENT A - Report of the Fort Collins Fluoride Technical Study Group, April 2003
(approximately 80 pages; a copy will be mailed to WRAB members)
Page 2
REPORT OF THE
FORT COLLINS
FLUORIDE TECHNICAL
STUDY GROUP
April 2003
The following agencies collaborated on the Fort Collins Fluoride Technical Study Group Process:
• Fort Collins Utility Department
• Health District of Northern Larimer County
• Larimer County Board of Health
In addition to the Fluoride Technical Study Group, the following people assisted in the development of
these findings:
• Fluoride Technical Study Group Research and Administrative Support
Susan Hewitt
Health District of Northern Larimer County
Fort Collins, Colorado
• Public Involvement Support
Patty Bigner
City ofFort Collins, Colorado
• Facilitation
Mike Hughes
RESOLVE
Denver, Colorado
Table of Contents
Table of Contents ........................................................................................................................1
Executive Summary iii
Introduction .................................................................................................................................1
Finding #1 - The Effectiveness of Drinking Water Fluoridation in Preventing Caries......... 9
Historical Perspective 9
How Fluoride Works ............................................................................................................................13
Evidence of Effectiveness of Community Water Fluoridation .............................................................14
Evidence of the Current Magnitude of Effectiveness ...........................................................................16
Studies of the Effectiveness of Community Water Fluoridation in Adults ..........................................18
Fluoridation-Ended Sites in Which No Caries Increases Were Found .................................................18
Gaps in Knowledge ...............................................................................................................................20
FINDINGS: The Effectiveness of Drinking Water Fluoridation in Preventing Caries (Cavities)........ 21
Reference List
Finding #2 - The Risk of Drinking Water Fluoridation 25
Total Exposure to Fluoride 25
FINDINGS: Total Fluoride Exposure ...................................................................................................30
Review of Potential Adverse Health Effects ..............30
Cancer 30
FINDINGS: Cancer ..............................................................................................................................34
Bone Fractures and Osteoporosis 34
FINDINGS: Bone Effects .............37
Skeletal Fluorosis ..................................................................................................................................37
FINDINGS: Skeletal Fluorosis .............................................................................................................40
Dental Enamel Fluorosis .......................................................................................................................40
FINDINGS: Dental Fluorosis ...............................................................................................................44
Thyroid Function 44
FINDINGS: Thyroid Function ..............................................................................................................45
Immune System Effects ........................................................................................................................45
FINDINGS: Immunological Effects .......46
Other Potential Health Effects ..............................................................................................................46
FINDINGS: Other Health Effects .........................................................................................................48
Reference List 49
Finding #3 - Costs and Benefits, Including the Distribution of Costs and Benefits.......... 51
Cost-Effectiveness of Community Water Fluoridation ........................................................................51
Distributional Effects of Community Water Fluoridation ....................................................................55
Effectiveness and Cost-Effectiveness of Other Fluoride Modalities Relative to
Community Water Fluoridation 56
FINDINGS: Costs and Benefits ............................................................................................................58
Reference List .......................................................................................................................................59
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of
Hydrofluorosilicic Acid 61
Background •..............,............................,........61
Fluoride Sources ..61
Fluoride Manufacturing Process ...........................................................................................................61
Methods of Application ........................................................................................................................61
Table of Contents i
Water Quality ........................................................................................................................................63
Analytical Information ..........................................................................................................................63
Uncertainties ........................................................................................................................................66
FINDINGS: The Potential for Increased Contaminate Levels Due to the
Use of Hydrofluorosilicic Acid .............................................................................................................71
Reference List .......................................................................................................................................72
Appendix A-1 - Fort Collins Fluoride Technical Study Group Tiered Reference List 73
First Tier.. .................................................................................................73
Other Literature Reviewed ....................................................................................................................74
Materials Submitted by Members of the Public ....................................................................................95
Appendix A-2 - Fluoride Mass Balance Calculations
City of Fort Collins Water Treatment Facility .......................................................................101
Appendix 1 - Effectiveness of Community Water Fluoridation
Methodological Approaches of "Tier One" and Other Reviews .........................................103
Tier 1 Reviews ....................................................................................................................................103
Other Reviews .....................................................................................................................................106
Appendix 2 - Risks According to "Tier One "Reviews ........................................................109
Introduction ......................................................................109
Cancer .................................................................................................................................................110
Bone Fractures and Other Bone Effects ..............................................................................................119
Skeletal Fluorosis 127
Enamel (Dental) Fluorosis ..................................................................................................................................133
Other Health Effects ...........................................................................................................................................144
Appendix 3 - Cost Effectiveness Studies .............................................................................159
Table 1: Cost-Effectiveness Studies, U.S ...............................................................................................159
Table 2: Cost-Effectiveness Studies, Other Countries ...........................................................................163
Table 3: Other Delivery Strategies for Fluoride ....167
Table 4: Other Strategies for Primary Prevention of Dental Caries .......................................................170
Economic Analysis of Community Water Fluoridation in Fort Collins, Colorado ................................172
References .174
Appendix 4 - The Potential for Increased Contaminant Levels Due to the Use of
Hydrofluorosilicic Acid ...........................................................................................................175
4.1 Material Safety Data Sheet Fluoride ........................................................................................175
4.2 Fluoride Manufacturing Process, Figures I and 2 ....................................................................181
4.3 Report Form 1 ..........................................................................................................................183
4.4 NSF Certification 184
4.5 Fort Collins Utilities Drinking Water Consumer Confidence Report, 2001 ............................188
4.6 Fort Collins Utilities Drinking Water Quality Summary, 2001 and 2002 ...............................190
4.7 Results for Iron, Copper, Manganese, Zinc, Cadmium and Nickel, Figures 3 - 9 ..................193
4.8 Arsenic Concentration in Finished Water ................................................................................194
4.9 Peer Reviews of the Masters and Coplan Report .....................................................................198
4.10 Lead Data Regression Analysis ..............................................•...............................................225
ii Report of the Fort Collins Technical Study Group - January 2003
THE FLUORIDE TECHNICAL STUDY GROUP
Executive Summary
The Fluoride Technical Study Group (FTSG) was charged with compiling a report that assesses risks and
benefits of community water fluoridation in order to assist risk managers (The Larimer County Board of
Health, the City of Fort Collins Water Board, and the Fort Collins City Council) to decide whether to
continue, alter or discontinue the City's water fluoridation program.
A more complete discussion of the FTSG's work and a description of the studies and findings are
contained in the attached report. This summary begins with five of the most important considerations
underlying the report and its findings, and then presents the findings themselves:
These are some of the essential considerations:
The FTSG elected to use a tiered approach to reviewing the existing literature on water fluoridation,
turning first to already conducted and published scientific literature research reviews and
compilations. Only when a gap in the data became evident or when a specific need for more
information was needed did the group turn to and evaluate published, peer-reviewed primary
studies.
2. The FTSG, for the most part, limited consideration to scientific studies of drinking water
fluoridation' at or around 1 milligram per liter (mg/L) or l part per million (ppm), because it is the
target amount of fluoride added to the City of Fort Collins water supply (range of 0.7 - 1.2 mg/L
with data indicating stringent control at 1.0 mg/L).
3. The levels of fluoride in untreated water range from 0.15 - 0.25 mg/L fluoride ion. If the City
were to end its water fluoridation program, the drinking water in Fort Collins would continue to
contain some fluoride.
4. The United States Environmental Protection Agency (EPA), under the Safe Drinking Water Act
(42 USC 300), promulgates the National Primary Drinking Water Regulations. These regulations
set the maximum contaminant levels (MCLs) for chemicals in finished water supplied by public
water systems. The EPA has established an MCL for fluoride of 4.0 mg/L.
5. The FTSG endeavored to create a balanced product for use by decision-makers that took into
account the most current and best available analysis of the weight of the scientific evidence on the
risks and benefits of community water fluoridation. The group also acknowledged that there are
gaps in the knowledge and uncertainties are inherent in the ability to fully understand what may
be subtle, yet important health effects that are yet to be detected via a weighted evidence
approach. Thus, the report includes stated uncertainties and areas where additional research is
needed to better understand the true benefits and risks.
FINDINGS
After considering public concerns and discussion-then focusing-the list of important questions, the
FTSG has developed consensus findings in four categories:
The effectiveness of drinking water fluoridation.
2. The risks of drinking water fluoridation and of cumulative exposure to fluoride from all sources,
including drinking water (over time) with specific attention to cancer, bone fractures, skeletal
fluorosis, dental fluorosis, thyroid function, and immune system effects.
Executive Summary iii
3. The costs and benefits of fluoridating the drinking water supply, and of not fluoridating the
drinking water supply, including assessing the distribution costs and benefits (equity), and
including the costs and benefits of using alternative methods to deliver fluoride.
4.The potential for increased contaminant levels in the drinking water due to the use of
hydrofluorosilicic acid in the fluoridation process.
Finding #1- The Effectiveness of Drinking Water Fluoridation in Preventing Caries (Cavities)
The weight of the evidence suggests that there is caries (cavities) reduction in populations exposed to
water fluoridation at or near an optimal level. The primary mode of action of fluoride in preventing caries
is its topical action on the surface of the teeth; systemic action from ingestion is now thought to play a
minor role. It appears that community water fluoridation is effective in all age groups in preventing dental
caries. This benefit amounts to a relative caries reduction of 25% and an absolute prevalence difference of
1.14 surfaces with caries in primary teeth and 0.5 surfaces with caries in permanent teeth in children
according to the most recent U.S. surveys of schoolchildren. Among the four studies of caries prevention
in adults, the most recent study showed that community water fluoridation reduced surfaces with caries by
0.35 surfaces per year of fluoride exposure. The benefit of drinking water fluoridation decreases as
individuals in the population receive fluoride from other sources (e.g., toothpastes, dental care, etc.). Even
with the limitations of some of the studies, there appears to be a net benefit in caries reduction from
drinking water fluoridation over and above that from toothpaste and other sources of fluoride. Among the
14 recent studies (completed after 1985) reviewed in which water fluoridation was discontinued, nine
showed an increase in caries rates. Five communities (all of them in other countries) that suspended water
fluoridation did not find that caries rates increased. It is uncertain to what degree changes in oral health
behaviors, introduction of new preventive programs and increased delivery of professional treatments in
response to cessation of fluoridation can account for these findings. Since these studies were conducted in
foreign communities in which there was socialized dental care and school-based oral health programs,
their results may not apply to Fort Collins.
Finding #2 - The Risk of Drinking Water Fluoridation
Total Fluoride Exposure
Total fluoride exposure must be considered when evaluating health effects. The amount of total fluoride
ingested will vary between individuals and is not precisely known. The FTSG review of the literature
finds that likely total exposure values for children older than six months living in communities with water
fluoridated at up to 1.2 mg/L (ppm) do not exceed the upper limit set to be protective of moderate dental
fluorosis by the Institute of Medicine. Total dietary exposures of fluoride can exceed this threshold
amount (0.7mg/day) in infants fed formula reconstituted with optimally fluoridated water.
Cancer
Although a small increase in cancer risk cannot be excluded, there is no consistent evidence from human
or animal studies that exposure to optimally fluoridated drinking water and other sources causes any form
of cancer in humans, including bone and joint cancer. The agreement between the epidemiological and
toxicological literature reduces the uncertainty associated with any one line of evidence finding.
Additional research is needed to address the remaining uncertainty whether community water fluoridation
may cause cancer in humans following long-term exposures of greater than 40 years.
Bone Effects
The FTSG agrees with the conclusion of the Medical Research Council of Great Britain that states, "The
possibility of an effect on the risk of hip fracture is the most important in public health terms. The
available evidence on this suggests no effect, but cannot rule out the possibility of a small percentage
change (either an increase or a decrease) in hip fractures" (Medical Research Council 2002, page 3).
iv Report of the Fort Collins Fluoride Technical Study Group - April 2003
Skeletal Fluorosis
At the concentrations of fluoride provided in Fort Collins water including exposures from all sources over
a lifetime, skeletal fluorosis caused by drinking water exposure is not likely to be a health issue. The
available data are not consistent with a likelihood of increased human skeletal fluorosis from city water
fluoridation.
Additional research is needed to reduce the remaining uncertainty if cumulative exposure to all sources of
fluoride (including drinking water fluoride at levels of 1 mg/L) over a lifetime may lead to pre-clinical or
milder forms of skeletal fluorosis in some sensitive populations
Dental Fluorosis
At the concentrations of fluoride provided in Fort Collins water, in combination with other sources of
fluoride, as many as one in four children under age S may develop very mild to mild dental fluorosis. This
degree of fluorosis may or may not be detectable by the layperson. With oral health as the goal, this
degree of dental fluorosis is considered an acceptable adverse effect given the benefits of caries
prevention. Since about 60% of dental fluorosis can be attributed to other sources of fluoride, particularly
toothpaste and other dental products, parental supervision over tooth paste swallowing in their young
children and proper prescribed supplementation in infants will likely reduce development of enamel
fluorosis more than the removal of added fluoride in drinking water.
Thyroid Effects
In the literature reviewed, doses appropriate for caries reduction were not shown to negatively impact
thyroid function. Studies in which humans received doses significantly higher than the optimum fluoride
intake for long periods of time showed no negative impact on thyroid function. For those with
hypothyroidism, the risks of alteration of thyroid structure or function are very low. The absence of our
finding any conclusive evidence that drinking water fluoride exposures causes increased risk to thyroid
function does not prove that fluoride can not affect thyroid function. The available data are consistent
with a finding of a low likelihood of risk to human thyroid function from water fluoridation.
Immunological Effects
Overall, evidence is lacking that exposure to fluoride through drinking water causes any problems to the
human immune system. The absence of our finding any conclusive evidence that drinking water fluoride
exposures causes increased risk to human immune system function does not prove that fluoride is
harmless to the human inirmine systems.
Other Health Effects
The potential for other health effects was reviewed by the FTSG. There was not adequate evidence to
consider any of these other potential adverse effects a concern with respect to fluoridation of Fort Collins
water supplies. The absence of our finding any conclusive evidence that drinking water fluoride
exposures causes other potential health effects does not prove that fluoride can not cause other potential
health effects.
Finding #3 - Costs and Benefits, Including the Distribution of Costs and Benefits
The research indicates that the public health goal of a reduction in the incidence of caries is better
achieved through community water fluoridation than through individual approaches. It requires minimal
behavioral changes compared to alternative delivery methods. It is effective in reaching people in all
socioeconomic strata.
The FTSG finds that, even in the current situation of widespread use of fluoride toothpaste and lower
baseline caries risk, it is likely that community water fluoridation remains effective and cost saving at
preventing dental caries, Based on best available evidence, suspending fluoridation of water in Fort
Executive Summary v
Collins would yield a net increase in costs of preventing and treating caries of approximately $4.25 per
person per year (range $3.22 - $10.31). The burden of caries is disproportionately borne by those with
lower socio-economic status. There is some evidence that water fluoridation reduces this inequality in
oral health.
Not considering the costs of enamel fluorosis or other potential adverse health effects may have led to an
over-estimation of the cost-savings of water fluoridation in Fort Collins. The magnitude of the costs of
adverse effects is likely to fall well below the estimated net savings.
In summary, this cost analysis assumes that there is a significant benefit from community water
fluoridation in preventing caries and that suspending community water fluoridation would result in a
relative increase in caries. It also assumes that potential adverse health effects are not significant. The
analysis also assumes that the city will continue using current fluoride additives (hydrofluorosilicic acid).
Using this set of assumptions, there appears to be a net cost benefit to community water fluoridation. If
any of these assumptions are not valid the cost-benefit picture could change significantly.
The FTSG did not review any study or measure that will achieve the same levels of prevention as water
fluoridation for the same resources.
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of
Hydrofluorosilicic Acid
The FTSG's review identified three potential concerns associated with hydrofluorosilicic acid (HFS). 1)
co-contamination (i.e. arsenic and lead), 2) decreased pH leading to increased lead solubility or exposure,
and 3) potential toxicological effects from incomplete dissociation products of HFS. The FTSG used the
raw and finished water quality data for the City of Fort Collins to determine whether the addition of HFS
was responsible for the potential addition of contaminants such as heavy metals to the city's drinking
water. There was no evidence that the addition of HFS increased the concentrations of copper,
manganese, zinc, cadmium, nickel, or molybdenum. The concentrations of arsenic and lead were below
the detection limit for the Fort Collins Water Quality Control Laboratory in both the source water and the
finished water and below the maximum contaminant level (MCL) for these naturally occurring elements.
There was no evidence that the introduction of HFS changed the pH of the water appreciably. Concern
that HFS incompletely disassociates may be unfounded when the fundamental chemical facts are
considered. Therefore, it is unlikely that community water fluoridation poses a health risk from the
exposure to any of these chemicals present in the water as it leaves the plant. Further studies related to the
health effects of HFS are in progress.
vi Report of the Fort Collins Fluoride Technical Study Group - April 2003
Introduction
In response to questions from the public about the risks, benefits and costs of community drinking water
fluoridation, the City of Fort Collins convened the Fluoride Technical Study Group (FTSG) to fulfill the
following responsibility:
• To explore information related to the costs and benefits of community drinking-water
fluoridation;
• To summarize what is known and not known about the risks and benefits of adding fluoride;
• To summarize what is known and not known about the risks and benefits of not adding fluoride;
• To develop and present findings;
• To base findings on the high quality scientific and technical information;
• To work toward consensus findings whenever possible;
• To clarify areas of agreement and of disagreement about the implications of the information;
• To integrate public input into the recommendations; and
• To present data, consensus findings and areas of disagreement to the Board of Health and the
Water Board so that these two boards can offer informed recommendations to the Fort Collins
City Council.
The Fluoride Technical Study Group (FTSG) includes nine community members with an interest in the
questions surrounding community drinking water fluoridation and with specific technical, medical or
scientific capabilities. The FTSG members are:
Ed Carr, DC, MS Gale McGaha Miller, BS
Chiropractor and Wellness Counselor Water Quality Services Manager
Fort Collins Utilities
Bruce Cooper, MD, MSPH
Medical Director Rami Naddy, PhD
Health District of Northern Larimer County Environmental Toxicologist
ENSR International
Greg Evans, DDS Member of City of Fort Collins
Pediatric Dentist Water Board
Kevin Gertig John Reif, DVM, MSc (Med)
Certified Colorado Water Works Professor
Operator A Department of Environmental Health
Water Production Manager Colorado State University
Fort Collins Utilities Water Treatment Plant
Frank Vertucci, PhD, MS
Adrienne LeBailly, MD, MPH * Certified Senior Ecologist
Director, Larimer County ENSR International
Department of Health and Environment Vice President of the
Larimer County Board of Health
* Although Dr. LeBailly's workload necessitated that she withdraw from the review process in Summer 2002, she
was very active in early meetings and helped establish guidelines and review criteria. She has continued to follow
the group's proceedings.
Introduction 1
Process
The Fluoride Technical Study Group (FTSG) met monthly as a full group, once each month, between
December 2001 and November 2002. During the report drafting process in the latter half of 2002, smaller
subsets of FTSG members met frequently to draft various sections of this document. The FTSG met three
times in December of 2002 to reach final consensus on the document. In addition, the FTSG held two
public meetings in early 2002 to invite input and advice from the public before beginning its work, and
two in early 2003 to present and discuss report findings.
Throughout the process, the FTSG encouraged ongoing public input. Of particular note is the fact that at
least one-third of the FTSG members examined every technical study, journal article, newspaper article or
videotape submitted by members of the public. All nine members reviewed those public submissions
deemed by any one member to be of significant scientific or technical merit, and therefore worthy of
inclusion in the FTSG deliberations. The technical and scientific information was assembled, reviewed
and distributed to the FTSG by Susan Hewitt of the Health District of Northern Larimer County, who also
-assisted in editing and preparing the final draft report.
The FTSG also made efforts to keep the public informed of the work that was being accomplished. All
FTSG meetings were open to the public, although no public comment was taken at these meetings.
Summaries of the public meetings and the FTSG meetings were posted'on a website maintained by the
Fort Collins City Utility Department. Additionally, three sets of the reference materials used by the FTSG
were available for review by members of the public at three locations in Fort Collins.
Priorities
In its earliest meetings (and after public meetings that elicited important topics) the FTSG prioritized the
key questions and centered its inquiry on developing findings in response to these priorities. The FTSG
reviewed the scientific and technical literature for infonmation about seven topics, six broad topics and
one specific to a single disease end point:
• The effectiveness of drinking water fluoridation
• The risk of drinking water fluoridation
• The risk of cumulative exposure to fluoride (over time) from all sources, including drinking
water,
• The costs and benefits of not fluoridating the drinking water supply, including assessing the
distribution costs and benefits (equity)
• The effectiveness of alternative methods of delivering fluoride
• The effectiveness of addressing fluoridation as a public health issue and the effectiveness of
addressing fluoridation as an individual choice
• The risk of impacts to thyroid function due to drinking water fluoridation
After generating its initial draft of this report, the FTSG has consolidated its findings into these four
topics:
1. The effectiveness of drinking water fluoridation.
2. The risks of drinking water fluoridation and of cumulative exposure to fluoride from all sources,
including drinking water, over time (with specific attention to cancer, bone fractures, skeletal
fluorosis, dental fluorosis and thyroid function).
3. The costs and benefits of fluoridating the drinking water supply, and of not fluoridating the
drinking water supply, including assessing the distribution costs and benefits (equity), and
including the costs and benefits of using alternative methods to deliver fluoride.
4. The potential for increased contaminant levels in the drinking water due to the use of
hydrofluorosilicic acid in the fluoridation process.
2 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Technical Study Group Literature Review Method
From the start, it was acknowledged that the published scientific literature base on community water
fluoridation was enormous and that it was beyond the scope of this group to conduct a systematic review
of thousands of primary studies. The FTSG elected to use a tiered approach to reviewing the existing
literature on water fluoridation, turning first to already conducted and published scientific literature
research reviews and compilations. Only when a gap in the data became evident or when a specific need
for more information was needed did the group turn to and evaluate published, peer-reviewed primary
studies. Initially, a half dozen comprehensive literature reviews were located and shared by the FTSG,
with additional studies and compilations located during the process. Ultimately, a tiered arrangement of
the literature utilized by the FTSG was compiled.
• "Tier One" literature were those by well-known, authoritative and unbiased national and
international public health agencies such as the United States Public Health Service, the World
Health Organization, the United States Centers for Disease Control and Prevention, the National
Institutes of Health, the Medical Research Council of Great Britain, and the British National
Health Services Centre for Reviews and Dissemination.
• The next tier included:
Published literature reviews and meta-analyses.
• Reports of primary studies published in peer-reviewed journals that were used to fill data
gaps or when additional explanation was needed.
• Literature reviews conducted by or contracted by municipal, provincial, or other local
governmental entities that were used for local decision making. These were primarily used to
identify "Tier One" studies and primary literature.
• Other materials considered by the FTSG included editorials, commentary and fact sheets, some of
which were supplied by members of the public.
Concerning "Tier One" and other literature, each of these studies used different search and review
strategies. Some used explicitly stated and highly systematic methods to evaluate the scientific merit of
studies, while others used more implicit and more subjective methods such as relying on an evaluation of
the quality of the literature by subject matter experts. The tiered reference list is provided in Appendix A-
L Additional information on the search and review strategies of many of the tier one literature and other
documents is presented in Appendix 1.
Study Criteria
The FTSG, for the most part, limited consideration to scientific studies of drinking water fluoridation at
or around 1 milligram per liter (mg/L) or 1 part per million (ppm), because it is the target amount of
fluoride added to the Fort Collins city water supply (range of 0.7 1.2 mg/L with data indicating stringent
control at 1.0 mg/L). In some cases, studies where experimental animals were dosed at a higher level or
human epidemiological or pharmacological studies of populations exposed to higher doses of fluoride
were considered by the FTSG to better understand potential cumulative or dose-dependent effects.
Please note the terms part per million (ppm) and milligrams per liter (mg/L) are used interchangeably
throughout this report. They are more or less equivalent and each term is used by the literature cited by
the FTSG. In layman's terms I ppm or 1 mg/L fluoride represents one "drop" of fluoride in one million
"drops" of water.
Weight of Evidence Approach With Uncertainties
Members of the FTSG used the weight of evidence approach in evaluating scientific studies. The EPA
defines the weight of evidence approach as "Considerations in assessing the interpretation of published
information about toxicity-quality of testing methods, size and power of study design, consistency of
results across studies, and biological plausibility of exposure-response relationships and statistical
Introduction 3
associations" (http://www.epa.¢ov/OCEPAterms/). Thus, all the scientific literature on a topic is
evaluated, with studies categorized into levels of better and lesser studies based do such variables as
degree of measurement accuracy, number of study subjects, how data was collected, control of potential
confounding factors and so on. The best studies get the most weight and the poorer studies less weight or
disqualification if a certain standard is not met. Particular attention is given when multiple studies, by
different researchers, using different methods, in varied population groups reach similar conclusions.
Such findings generally corroborate hypotheses and are particularly useful when looking for subtle health
changes due to the large numbers of subjects measured. The converse is also important, if multiple studies
show contradictory positive or negative effects then no overall effect is discernable and hypotheses may
be refuted before a link is made to potential harm or benefit. The FTSG acknowledged uncertainties are
inherent when scientific literature is evaluated.
Some members advocated for the precautionary principle, defined by the EPA as "When information
about potential risks is incomplete, basing decisions about the best ways to manage or reduce risks on a
preference for avoiding unnecessary health risks instead of on unnecessary economic expenditures"
(http://www.epa.2ov/OCEPAtermso. In other words, to assist the risk managers, the weight of evidence is
considered as well as the magnitude of the calamity that a worst-case scenario may produce if the
evidence is flawed or inaccurate.
The FTSG endeavored to create a balanced report for use by decision-makers that took into account the
most current and best available analysis of the weight of the scientific evidence on the risks and benefits
of community water fluoridation. The group also acknowledged that there are gaps in the knowledge and
uncertainties are inherent in the ability to fully understand what may be subtle, yet important health effects
that are yet to be detected via a weight of the evidence approach. Thus, the report includes stated
uncertainties and areas where additional research is needed to better understand the true benefits and risks.
Strengths and Limitations of Epidemiology and Toxicology Approaches..
The potential risks of exposure to fluoride among human populations can be evaluated in essentially two
ways. In the first approach, laboratory animals are tested under controlled conditions and exposed to
known quantities of fluoride in water or food for varying lengths of time. Toxicological studies attempt to
derive dose-response relationships between exposure to fluoride and some measure of organismal
response. Measured responses may include mortality, changes in growth, reproductive capacity or the
incidence of cancerous lesions. In some studies, rodents are exposed over their entire lifetime, up to two
years. These studies typically include histologic examination of tissues at the end of the study to detect
microscopic lesions in multiple organs. Doses of fluoride given to animals are often much higher than
doses that would typically be, encountered by a person.
Extrapolation of dose-response toxicity tests in animals to the prediction of human risks from drinking
water exposure to fluoride is complicated by many factors. Findings must be extrapolated between the
differences in doses used in animal studies and the range of human exposures associated with the
consumption of lmg/l (Ippm) of fluoride in fluoridated drinking water. Animal responses can vary
compared to human responses, and there is always uncertainty associated with extrapolation from test
species like rodents to humans. Absence of a dose-response relationship between a stressor and a response
is considered strong evidence that the stressor is not likely to cause a response. However, the absence of
any observed dose-response relationship between a stressor and a response does not prove that the
stressor cannot cause a response.
The second approach to assessing risk to humans incorporates epidemiologic studies of human
populations. These studies involve comparing the incidence of various potential health effects among
populations exposed or not exposed to fluoride or comparing the frequency of exposure to fluoride among
persons with and without a certain disease. The advantages of the epidemiologic approach are that they
4 Report of the Fort Collins Fluoride Technical Study Group - April 2003
are conducted in the species of interest (humans), the exposures are at relevant levels and the study is done
by observational, rather than experimental methods under "natural" conditions.
The disadvantages of epidemiologic approaches are that they may make it difficult to accurately assess
exposure over time due to lack of individual level data about diet, water consumption patterns, fluoride
concentrations, etc. These studies are also subject to a variety of biases found in observational research.
Principal sources of bias in epidemiologic studies include 1) confounding - where there may be exposure
to another variable that may be more common among those exposed that is also a risk factor for the
disease, resulting in an over- or under-estimate of the true risk; 2) selection bias due to an inability to
study entire populations, resulting in a biased sample of participants whose exposures or disease patterns
are not representative of the population from which they are drawn; and 3) information bias, where
information about exposures, outcomes or other factors may be inaccurate due to problems with recall,
residential mobility, lack of adequate exposure data and other data inadequacies.
The FTSG reviewed the toxicological and epidemiological studies as independent lines of evidence. The
weight of evidence findings are stronger when the toxicological and epidemiological studies agree.
However, either line of evidence may carry enough weight on its own to be convincing as to the benefits
or risks of a particular substance. In one example, the EPA's recent ruling to lower the maximum
contaminant level for arsenic in drinking water from 50 µg/liter to 10 µg/liter came solely from
epidemiologic studies indicating an increased risk of cancer in exposed human populations. Also in the
cancer arena, toxicological evidence may stand alone if a substance is tested repeatedly in several
experimental test species (such as rats, mice, and hamsters) at suitable doses, and a specific cancer is
detected consistently in a sufficient proportion of test animals. The toxicological evidence is much
stronger when the same substance is also shown, in a variety of genetic test systems, to have DNA-
damaging effects (genotoxicity) that have been associated with cancer in humans.
Risk and Benefit Assessment and Risk Management
The charge of the FTSG was to compile a report that assessed risks and benefits of community
water fluoridation in order to assist the risk managers (i.e., the Larimer County Board of Health,
the City of Fort Collins Water Board, and the Fort Collins City Council). The FTSG found the
following explanation of risk management by the Medical Research Council of Great Britain to be
particularly useful:
"Once the risks and benefits have been assessed, this information must be set alongside other
considerations, such as the financial cost of the policy or action, and a decision then made
on whether to implement the change. This is not simply a matter of science - it involves
value judgments, and individuals may weight the risks, benefits and attendant uncertainties
differently. If the decision must be taken at the community level (as with water
fluoridation), it often falls to democratically elected representatives and may follow wider
public consultation and debate" Reference cited: Medical Research Council (2002)
Working Group Report: Water Fluoridation and Health. London, U.K.: John Wright, p. 7.
Statutory Authority for Fluoride Used in Community Water Fluoridation
The United States Environmental Protection Agency (EPA), under the Safe Drinking Water Act (42 USC
300), promulgates the National Primary Drinking Water Regulations. These regulations set the maximum
contaminant levels (MCLs) for chemicals in finished water supplied by public water systems. Based on a
report by the National Research Council, the EPA has established an MCL for fluoride of 4.0 mg/L. The
National Sanitation Foundation (NSF) certifies drinking water additives if they are shown to contribute
less than 10% of the MCL to the finished water supply for all drinking water contaminants regulated by
the EPA. As stated above, the level of fluoride in Fort Collins treated water supplies is stringently
controlled at 1.0 ppm (range from 0.7 to 1.2 ppm). The Fort Collins Utilities Water Treatment Program
Introduction 5
complies with all regulations set forth by the EPA for fluoride, uses products that are certified by the NSF,
and meets or exceeds all recommendations set forth by the Colorado Department of Public Health and
Environment (CDPHE) as well as by the United States Centers for Disease Control and Prevention (CDC).
Several individuals at-the initial public meetings suggested that fluoride should be treated as a drug that is
added to community water and wondered why the United States Food and Drug Administration (FDA)
does not regulate fluoride in drinking water. The FTSG noted that FDA considers the intended use of
products when determining whether or not an "article" is a drug, as opposed to a cosmetic, a food or
beverage, or none of these. The intended use of the high concentrations of fluoride in toothpaste and other
dental products meets the FDA's definition of a drug, i.e., drugs ale "(A) articles intended for use in the
diagnosis, cure, mitigation, treatment, or prevention of disease and (B) articles (other than food) intended
to affect the structure or any function of the body of man or other animals" [FD&C Act, sec. 201(g)(1)].
Consistent with this definition, when fluoride is added to bottled water, the FDA regulates the product as
a food, because of its intended use. The EPA, rather than the FDA, has the authority in the U.S. to
regulate maximum levels of fluoride in drinking water. In addition, the U.S. Public Health Service and
state public health authorities are charged with issuing recommendations regarding optimal levels of
water fluoridation for purposes of preventing caries, and the decision to fluoridate water is left to the
impacted population's elected officials. The FTSG did not address questions of legal definitions or the
distribution of regulatory authority in investigating the four outlined objectives as previously stated.
Important Background Information Relevant to the Fluoridation of Community Water in
Fort Collins Colorado
History of Fort Collins Water Fluoridation Program
In 1954, an ordinance to fluoridate was presented to Fort Collins voters, but did not receive sufficient
votes to pass. In 1966, the Fort Collins City Council adopted an ordinance prohibiting fluoridation unless
approved by a vote of the public. Citizens voted in 1967 to authorize City Council to add fluoride to Fort
Collins water supply system. That year Fort Collins began adding dry sodium silicofluoride to the treated
drinking water supply at Water Treatment Plant #1. In 1992, the City changed to a liquid form of fluoride
called hydrofluorosilicic acid (HzSiF6). This practice continues to the present.
Natural or Background Levels of Fluoride
The FTSG felt it was important for the decision-makers and the general public to know that the source
waters used by the City of Fort Collins (Cache La Poudre River and Horsetooth Reservoir) contain some
natural amounts of fluoride. The levels in untreated water range from 0.15 - 0.25 mg/L fluoride ion. This
is below the level considered by public health authorities to be "optimal" for caries prevention. Natural
fluoride is not removed during the water treatment process. If the City were to end its water fluoridation
program, the drinking water in Fort Collins would continue to contain some fluoride.
Fort Collins Area Water Providers
In addition to Fort Collins Utilities, there are three additional water utilities serving the Fort Collins area
(East Larimer County Water District, Fort Collins-Loveland Water District and North Weld County
Water District). Currently, Fort Collins Utilities and these districts fluoridate at 1 mg/L. Neighboring
districts sometimes share water. If Fort Collins Utilities ceased to fluoridate the water and some or all of
the other districts continued to do so, some customers served by Fort Collins Utilities would receive
fluoride in the drinking water ranging from 0.2 to 1.0 mg/L. Customers would need to contact their
supplier to detennine the level of fluoride in their water.
Review of Water Treatment Process Chemistry
Fort Collins Utilities uses what is termed `Conventional Treatment' for its two raw water sources. Cache
La Poudre River and Horsetooth Reservoir waters are blended and then treated using several different
6 Report of the Fort Collins Fluoride Technical Study Group - April 2003
chemicals. Each added treatment chemical is defined below and shown, beginning from left to right, on
Figure 1
The water treatment chemicals used at the Fort Collins Water Treatment Facility are purchased or
prepared in highly concentrated forms. Many of these concentrated chemicals are hazardous prior to their
addition to the raw (untreated) water. However, once added to the raw water, these chemicals are diluted
and become harmless, if not helpful. A fundamental concept in toxicology that addresses this
phenomenon was first described in the sixteenth century by Paracelsus, "All substances are poisons; there
is none which is not a poison. The right dose differentiates a poison from a remedy."
Thus, any review of the "safety" of drinking water additives must keep in mind that the dose determines
whether the additive is helpful or poisonous.
The reader should refer to Figure I to review where each of the chemicals described below are added in
the treatment process.
Chforlne Dioxide (CIO,) Polymers (flocculant aid and filter aid)
Powdered Activated
Carbon Alum (AI,(SO,), H2O)
Lime (Ca(OH)=}
Raw Poudre E-Garbon Dioxide (CO,)
Flocculation R
River Water Flow Blend Coagulation Sedimentation Filtration
Raw Horsetooth -ff4 I
Reservoir Background
Water Fluoride = 0.2 mgJL
1
Ciearwell Sample
Station
t
West East
Chlorine Reservoir Reservoir
Lime (Ca(OH)2)
Carbon Dioxide (CO,)
Fluoroslllclc acid (HFS) Fluoride = 1 0 mgtL Fluoride = 10 mgil
(Added Fluoride = 0.8 mglL)
Fort Collins Water Treatment Facility
Process Schematic Sample
Station To
and 2►Distribution
Location of Chemical Feed Points (ss2) System
Figure 9
Chlorine Dioxide (C102) - used as a pre-oxidant for Horsetooth Reservoir raw water to aid in the removal
of certain contaminants. C102 is made on site using a highly automated process. Chlorine, sodium
chlorite, and water are blended to form chlorine dioxide solution. The solution varies in strength and
dosage based on raw water quality. C102 is a strong oxidant and requires special handling and feed
equipment. C102 disassociates to chlorite and chlorate ions as well as chorine and hydrogen ions.
Powdered Activated Carbon (PAC) - PAC is used for removing compounds that cause taste and odor.
PAC is added at dosages dependant upon raw water quality conditions. Carbon does not change chemical
form after addition and is settled out of the process after addition.
Introduction 7
Calcium Hydroxide or Lime [Ca(OH)21 - Lime is added to the raw water to adjust the alkalinity of the
raw water prior to coagulation. Alkalinity is a measure of the buffering capacity of the water and is
typically expressed as mg11 of calcium carbonate (CaC03). When lime is added to water, calcium ions are
released and the alkalinity and pH go up (due to the increase in OH' that is released from the lime).
Dosages vary from 5 - 35 mg/L. Lime is very basic (pH 10.5).
Carbon Dioxide (C02) - CO, gas is used to adjust the pH of the raw water after lime addition (see Lime).
C02 forms a weak acid when added to water - carbonic acid (H2C03).
Aluminum Sulfate or Alum (A12(SO4)3+ 14H2O) - Alum is added to the water to coagulate the particles
that are present in raw, untreated water. Since alum is positively charged, and most particles are
negatively charged, the particles agglomerate in the flocculation stage, and settle out in the unit process
called sedimentation. Alum is slightly acidic (pH of 1 % solution = 3.5). When alum is added to water,
the salts dissociate to their respective trivalent ions, Al''+` and then form hydroxyl complexes
(AI(H20)6") .
Polymers (Cationic and Anionic)- Polymers are added to the process to aid in settling the larger particles
that are formed in the coagulation and flocculation processes. Different types of polymers are utilized
depending on the raw water source and quality. Dosages are applied at very low concentrations (0.01-
0.2 mg/L). Since polymers are long chained organic compounds, they do not change form and are
removed with the particles that are settled and filtered out of the water.
Chlorine (C12) - Chlorine is added to disinfect the water after filtration. Although chlorine is hazardous as
a gas form, when added to water, C12 disassociates to hypochlorous acid (HOCI') and hydrochloric acid
(HCI). The HOCI- is the form that disinfects the water. Dosages applied are dependant upon many water
quality factors, however regulations require that a minimum of 0.2 mg/L C12 remain in the water at the
furthest end of the piping system that delivers water throughout our community.
Lime - Lime is also added at the clearwell to adjust the alkalinity of the finished, potable water (38 - 40
mg/L as CaC03). Alkalinity is a measure of the buffering capacity and is typically expressed as mg/L as
calcium carbonate (CaCO3). Again, when lime is added to the water, calcium ions are released and the pH
goes up (due to the increase in OH- that is released from the lime).
Carbon Dioxide - See above. C02 is used to adjust the pH of the finished, potable water. C02 forms a
weak acid when added to water - carbonic acid (H2CO3). The final pH target for our community is strictly
controlled (pH 7.8 - 8.0 units).
Fluorosilicic Acid (HFS or H2SiF6) - Fluoride is added as a liquid with very precise metering and flow
measurement equipment. Liquid HFS is acidic and once added to water, it dissociates and will lower the
pH of the solution. In Fort Collins, both lime and carbon dioxide are added to maintain strict pH targets of
the finished water (see Figure 2).
8 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Raw Poudre
River Water Flow Flocculation &
Blend Coagulation Sedimentation Filtration
Raw Horsetooth
Reservoir Background
Water Fluoride = 0.2 mg/L
Clearwell Sample
Station
1
HFS FEED West East
(Added Reservoir Reservoir
Fluoride
= 0.8 ni Fluoride = 1.0 mg/L Fluoride = 1.0 mg/L
Fort Collins Water Treatment Facility
Process Schematic Sample
and station To
2 Distribution
C Location of HFS (Fluoride) Feed (ssz> System
Figure 2
When HFS is added to water, hydrofluoric acid (HF) and silicon tetrafluoride (SiF4) are formed. Silica
tetrafluoride is a gas that reacts quickly with water to form silicic acid (H2SiO3) or silica NOD and HF.
The HF further dissociates to hydrogen and fluoride ion. The concentration of fluoride is strictly
controlled to a target level of 1 mg/L as fluoride ion.
Overview of Fluoridation Chemistry
An overview of the chemistry of HFS addition and what happens when it is dissolved in water is
provided. Another overview, written by an independent research group commissioned by the British
Fluoridation Society can be found at: httn://www.liy.ac.ltk/bfshvivreportd3df. For detailed recent scientific
reviews of this issue, the reader should consult Urbansky and Shock, 2000 and Urbansky, 2002.
Equilibrium
The equilibrium reaction between the strong acid hexafluorsilicic acid (HFS) and water can be
represented in chemical shorthand as:
SiF62" + 4H2O Si(0H)4 + 4H+ + 6F"
The dissociation of hexafuorsilicate ion (SiF62-) to the products on the right hand side of the above
equation is considered to be complete at equilibrium at the normal pH of municipal water supplies (pH >
7.0). In Fort Collins, the pH is strictly maintained at a range of 7.8 - 8.0 pH units. Complete dissociation
at equilibrium means chemists would report, based on the most conservative (smallest) equilibrium
constants in the chemical literature, that the ratio of Si0H4/SiF67" at pH 8 and a F- concentration of 1 mg/L
would be about I x I OE26.07. That means that for every 1 molecule on non-dissociated SiF6 2" there are
10,000,000,000,000,000,000,000,000 molecules of Si(OH)4. The resulting concentration of SiF62- at
equilibrium in drinking water supplies where F- is adjusted with HFS to be 1 mg/L would be exceedingly
small (<<< 1 part per trillion).
Introduction 9
The time to achieve this equilibrium is not precisely known. However, it is known to occur within in
seconds, if not minutes, in complex aqueous chemistry. Since it takes more than six hours for treated
drinking water to reach Fort Collins homes, there is more than ample time for SiF62- to reach equilibrium
(i.e., to essentially fully dissociate) before any resident ingests the treated water.
Further validation of the dissociation of HFS to F" during Fort Collins water treatment comes from the
chemical mass balance calculations between the known amount of added HFS and the resulting measured
F- ion concentration presented in Appendix A-2. If large amounts of HFS were not dissociated it would
be observed in the mass balance of HFS dosage versus the resulting F- ion concentration.
It is important to put the mass balance findings into the context that no more than 66% dissociation was
determined by the Westendorf, 1975 thesis cited by Masters et al 2000 (See Finding #4). This thesis
finding is the "experimental evidence" cited to call into question the literature dissociation constants
suggesting nearly 100% dissociation reported by Urbansky and Schock 2000, and Urbansky 2002. Since
the mass balance using the F- ion electrode method (ISE) is balanced within 3% (Mass Balance
Calculations, Appendix A-2), the Fort Collins Water Treatment Facility (FCWTF) monitoring data does
not support the claim that 33% or more of the HFS added is undissociated and remains in the water
supply for Fort Collins. The mass balance reported an error of 3% and hence the analytical result
demonstrates the dissociation of the Y ion. Given the precision in the values used for flow rate, applied
dosage rate, HFS added in pounds per day, and the F- ion concentration, the budget 3 % is within
measurement error. The FCWTF data are consistent with the prediction of complete dissociation of HSF
based on chemical equilibrium theory.
10 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Finding #1 W The Effectiveness of Drinking Water Fluoridation in
Preventing Caries
Historical Perspective
In 1901, a Colorado Springs dentist recognized that his patients with teeth with a brown stain or mottled
dental enamel also had a very low prevalence of cavities (also called caries) (Centers for Disease Control
and Prevention [CDC], 1999b). At this time in history, extensive dental caries were common, so this
observation and its subsequent correlation with high amounts of fluoride ion in the water supply (2.0 -
12.0 milligrams per liter, mg/L) proved to be significant. Another dentist, H.T. Dean, DDS., took this
information and conducted a survey of dental caries in relation to natural concentrations of fluoride in
drinking water of 21 U.S. cities (Committee to Coordinate Environmental Health and Related Programs,
USPHS [USPHS], 1991 pp. 18-19; CDC, 1999x, p. 934). Dean observed that at a concentration of 1 mg/L,
fluoride would significantly reduce caries while causing a low incidence of mottled enamel, now called
fluorosis, of the mostly very mild type. Beginning in 1945 and 1946, community trials were conducted
over 13-15 years in four pairs of cities in the U.S. and Canada. These studies found a 50-70% reduction of
caries in children following addition of fluoride (in the form of sodium fluoride) to community water
supplies at 1 mg/L. The incidence of mild fluorosis remained low (CDC, 1999a, p. 936). Some of the
early studies were criticized for lacking appropriate controls, not applying randomization, and not
controlling for potential examiner bias (Sutton, 1960). However, the large effect sizes in these trials,
along with replication of these findings in subsequent studies, led to the acceptance of community water
fluoridation as a public health approach to caries prevention.
Since those early times, community water fluoridation and the use Of fluoridated water in the production
of foods and beverages have become widespread. Beverages and foods prepared with fluoridated water
contain fluoride. When these processed products are transported to nonfluoridated communities for sale,
people consume them and ingest fluoride (Lewis & Banting, 1994, p. 156). People also travel across
"fluoridation boundaries" to work or to attend school. This has been called the "halo" or "diffusion
effect" and accounts for some of the narrowing difference in fluoride intake between fluoridated and
nonfluoridated communities (CDC, 2001b, p. 9). A "reverse diffusion effect" also occurs, in which
products from fluoride-deficient communities are ingested by people living in fluoridated areas. This has
the same leveling'effect when caries rates between fluoridated and nonfluoridated communities are
compared (Ripa, 1993, p. 23).
Another trend that has contributed to a lowering of caries rates in both fluoridated and nonfluoridated
communities has been the successive introduction of readily available fluoride products since the 1950s,
including topical gels, fluoridated toothpaste, fluoride supplements and mouth rinses (Ripa, 1993, p. 23).
With the introduction of fluoridated toothpaste in 1965 (at 1100 mg/L), the use of fluoridated dental
products has become widespread. Between 1972 and 1983, fluoridated toothpaste sales in the U.S. market
increased from about 70% to more than 95% (Driscoll, et al., 1986, pp. 50-51).
The level of dental decay in a population is typically summarized by measures of its distribution and its
severity. Prevalence of caries-the percent of the population with any caries-is the most widely used
measure of distribution. Severity of dental decay is measured as the mean number of decayed, missing
and _filled teeth (abbreviated "dmft" for primary teeth or baby teeth and "DMFT" for permanent teeth) or
the mean number of decayed, missing or -filled surfaces (abbreviated "dmfs" for primary tooth surfaces
and "DMFS" for permanent tooth surfaces).
As a consequence of many factors, including fluoridation of public water supplies, almost universal use of
fluoride products, and improved oral health behaviors, there has been a reduction in caries levels in the
U.S. and many other established market economies since the 1970s. As shown in Table 1 (Featherstone,
Finding 41 r The Effectiveness of Drinking Water Fluoridation in Preventing Caries 11
i
1999, p. 32), national surveys of decay in children demonstrated dramatic decreases in both prevalence and
severity in the 1970s and 1980s. Recent smaller surveys indicate that the decline in caries may have stalled
since then (Featherstone, 1999, p. 31). The current national survey, NHANES IV, began collecting measures
of dental caries, sealant use and enamel fluorosis in 1999. This survey will help determine whether or not
caries rates in the U.S. have stabilized or continued to fall (http://www.ede.gov/nehs/nhanes.htm).
Table I
Mean DMFS and % Caries Free in Four U.S. Surveys
Age Range NCHS - NIDR 1 NIDR 1 NHANES III %
1971-74 1979-80 1986-87 1988-91
5-11 DMFS 3.0 2.0 1.2 .9
% caries free 44% 58% 70% 74%
12-17 DMFS 10.4 6.8 4.7 4.4
% caries free ' 10% 17% 27% 33%
(adapted from Featherstone, 1999, p 32)
" NCHS National Center for Health Statistics
NIDR -National Institute for Dental Research
National Health and Nutrition Examination Survey
The extent of water fluoridation in a region determines the magnitude of the diffusion effect. This was
evident in the 1986-87 National Institute of Dental Research (NIDR) survey of school children. The
Midwest region had the highest percentage of the population having water fluoridation (72%) and the
lowest difference in mean or average caries scores (-5.6%) among the seven U.S. regions, while the
Pacific region had the lowest water fluoridation coverage (18%) and the highest difference in mean caries
scores (61 (Ripa, 1993, p. 23). In Region V (Texas, Oklahoma, New Mexico, and Colorado) 57% of
persons was living in fluoridated communities and an 8% difference in average caries scores were found.
The 1986-87 NIDR survey is the most recent and geographically relevant data the Fluoride Technical
Study Group (FTSG) found to estimate caries levels in the Fort Collins area.
Even though overall decay rates on all tooth surfaces have fallen dramatically in children, caries continue
to be an important public health problem. However, the distribution of the problem has changed over the
past two decades. First, the distribution of decay among children has become skewed, with one quarter of
children accounting for 80% of the caries experience in permanent teeth in the U.S. (Kaste, et al., 1996
According to the Centers for Disease Control and Prevention:
"Lower-income, Mexican American and African-American children and adults have more
untreated decayed teeth than their higher-income or non-Hispanic white counterparts (4,5,8,9).
Among low-income children, approximately one-third have untreated caries in primary teeth that
could be associated with pain, difficulty in eating, and underweight (9)" (CDC, 2001 a, p.2).
Second, the distribution of caries in the mouth has changed. Fluoride and brushing are both less effective
in preventing caries on pit-and-fissure surfaces (the chewing surfaces) of teeth, leading to lesser
reductions in caries on these surfaces than on the smooth tooth surfaces (U.S. Department of Health and
Human Services [USDHHS, ]2000, p. 38). The width of most pits and fissures is smaller than a
toothbrush bristle, making cleaning of their deep recesses almost impossible. The debris that accumulates
forms a mechanical barrier that is thought to impede the flow of topical fluoride to these recesses.
According to national surveys, the majority of all dental caries in school-age children now occurs on pit
and fissure surfaces (Kaste et al., 1996 ; USDHHS, p. 166).
Finally, there has been a shift in the burden of caries from children to adults, due to the fact that tooth
retention has increased among older adults over the past several decades (CDC, 2001b, p. 11). Gingival
tissues tend to recede over time, exposing the tooth root to cariogenic bacteria that can cause root caries.
12 Report of the Fort Collins Fluoride Technical Study Group - April 2003
The latest national survey, the 1988-91 NHANES III, found that only 7%0 of adults with teeth were caries
free. Figure 1 shows the marked increase in caries experience with age.
I
Mean Number of Decayed, Missing or Filled
Surfaces per Person by Age, NHANES III
100
.1
7073
80 -
60 - - X58
40 ~r40-
20 - .x'24-
0 1 4 --+'12
5-11 12-17 18-24 25-34 35-44 45-54 55-64 65-74 75+
Age Range
I
Figure 1. Mean caries levels by age, U.S., 1988-91
The first questions that the FTSG addressed were, "What is the effectiveness of community water
fluoridation in preventing caries?" and "Is there an effect over and above that of fluoride in toothpaste and
other dental products and processed foods and beverages?"
How Fluoride Works
The main benefit of fluoride is that it inhibits dental decay. The basic process of decay begins in the
bacteria-rich coating of the teeth called plaque (Featherstone, 1999, p. 32). Certain bacteria produce acids
when they digest fermentable carbohydrates such as sugars and cooked starch. These acids can dissolve
the calcium phosphate mineral of the enamel or dentin resulting in a carious or "white spot" lesion-a
process called demineralization. The process of demineralization occurs each time carbohydrates are
taken into the mouth. If not halted or reversed, the carious lesion progresses and a cavity is formed. If
fluoride is present in the saliva and plaque fluid at the time bacteria is producing acid, it diffuses into the
crystal surface with the acid and inhibits demineralization. Fluoride also enhances remineralization if a
carious lesion begins to form and the remineralized surface is then more resistant to caries. Fluoride also
interferes with the production of acid and adhesion by bacteria-whether this reduces the caries
producing potential of bacteria is unclear (CDC, 2001b, p. 3).
Early theories about how fluoride worked held that it needed to be incorporated into developing enamel
before the tooth erupted or emerged from the gums (CDC, 2001 a, p. 4). Therefore, it needed to be
swallowed by infants and children in order to reduce risk of caries. However, according to recent reviews,
laboratory and epidemiological research over the past two decades indicates that fluoride's predominant
effect is post-eruptive and topical and therefore of benefit to adults as well as children (CDC, 2001b, p. 4;
Featherstone, 1999; Locker, 1999). Most of the benefits of water fluoridation appear to accrue the same
way they do for toothpaste and other dental products-through frequent topical exposures.
"When fluoridated water is the main source of drinking water, a low concentration of fluoride is
routinely introduced into the mouth. Some of this fluoride is taken up by dental plaque; some is
transiently present in saliva, which serves as a reservoir for plaque fluoride; and some is loosely
held on the enamel surfaces (76). Frequent consumption of fluoridated drinking water and
beverages and food processed in fluoridated areas maintains the concentration of fluoride in the
mouth" (CDC, 2001b, p. 9).
finding 4l The Effectiveness of Drinking Water Fluoridation in Preventing Caries 13
I
That does not mean that ingestion (swallowing) of fluoride does not contribute to caries prevention benefits.
An analysis of data from the Netherlands estimated that, for 15 year olds, half of the reduction in caries
attributable to fluoride exposure was due to pre-eruptive exposure and half due to post-eruptive exposure,
and that the best protection is achieved if fluoridation is available from birth (Groeneveld, 1990; reviewed
by Ripa, 1993, p. 26). The relative benefits of pre and post-eruptive fluoride have yet to be resolved.
The fact that water fluoridation's major benefit is topical, combined with the fact that potential adverse effects
can only be caused by systemic absorption, was an important concern to the FTSG. However, evidence
suggests that the pre-eruptive benefits of water fluoridation, although smaller, should not be overlooked.
Evidence of Effectiveness of Community Water Fluoridation
The FTSG's Approach
The potential effectiveness of exposure to fluoride in preventing and controlling caries can be evaluated
from observation (epidemiologic studies) or experiment (randomized trials). With either approach, the
researcher compares measures of caries among a group exposed to fluoride versus measures of caries in a
concurrent or historical group that was not exposed or was less exposed. Randomized clinical trials (with
concurrent controls, double blind design and placebos) are considered the gold standard of evidence for
effectiveness of a clinical treatment. Such experiments have shown that fluoride delivered in toothpaste,
mouthwash, gels, supplements and varnishes reduce caries (CDC, 2001b, pp. 20-21; USPHS, 1991, p.
27). However, it is not possible to conduct randomized controlled experiments to measure the
effectiveness of adding fluoride to community water supplies. Study subjects (members of communities)
can neither be randomly allocated to treatment and control groups, and it is difficult to blind examiners to
whether or not study subjects are living in a fluoridated community (CDC, 2001b, p. 20). Therefore,
evidence of the effectiveness of community water fluoridation must be based on observational studies.
Since the researcher does not control the allocation of treatment in an observational study, there is a
potential for the validity of such studies to be threatened by a variety of biases. Some study designs are more
vulnerable than others. Furthermore, because background caries rates have dropped since the early
community trials, and differences between exposed and non-exposed individuals have narrowed, biases
introduced by weak study designs could be large enough to mask a true difference in caries measures or
demonstrate a difference when one does not exist (Expert Panel for Water Fluoridation Review, City of
Calgary, 1998, p. 23). Therefore it is critical that both the quantity of studies and their quality be considered
in assessing the weight of evidence regarding the current effectiveness of community water fluoridation. A
thorough assessment of the evidence requires a systematic approach to searching for and selecting studies to
include and to assess their validity.
The FTSG's approach was to identify recently published comprehensive summaries of the evidence of
water fluoridation effectiveness commissioned by health authorities, to evaluate how each review protected
against biases (review quality), to highlight findings of reviews of high quality, and to use all reviews to
identify areas of uncertainty. A subset of eight of the fluoride evidence reviews initially selected by the
FTSG addressed the issue of the effectiveness of community water fluoridation. Descriptions of the
approaches of each of these reviews to collecting and weighing the evidence regarding the benefits of
community water fluoridation are found in Appendix 1. The FTSG identified five comprehensive reviews
published since 1990 in which the review or research panel made an attempt to identify all relevant research
and evaluate the threats to validity of individual studies. Four were commissioned by national health
authorities and one by a provincial government. Two of the reviews specifically addressed the question of
whether the effectiveness of water fluoridation remains significant in the current context of lower mean
caries levels and widespread exposure to other sources of fluoride (National Health Service Centre for
Reviews and Dissemination, University of York [NHS], 2000; Locker, 1999).
(76) Reference within a quote is available in the source document.
14 Report of the Fort Collins Fluoride Technical Study Group - April 2003
The FTSG first reviewed the four nationally commissioned studies and their findings. The group then
described evidence of the declining magnitude of effectiveness in recent times. Finally, the FTSG examined
several recently conducted epidemiological studies in which no caries benefit was found to ascertain why
this might be.
What Recent Comprehensive Reviews Found
In 1991, the Ad Hoc Subcommittee on Fluoride convened by The U.S. Department of Health and Human
Services and the United States Public Health Service (USPHS) published their comprehensive review and
evaluation of the public health benefits and risks of fluoride in drinking water (USPHS, 1991). Using the
traditional epidemiological criteria for establishing causation, the Subcommittee found:
"The reduction in dental caries among persons exposed to fluorides fulfills all the criteria for a
causal relationship: an association was found with a dose-response effect, the findings were
replicated under a great variety of circumstances by different investigators, alternative
explanations and observer bias have been excluded, the findings are biologically plausible, and
the effect, prevention of dental caries, continues to show that the fluoridation of water supplies
substantially reduces the scores of dental caries. The decline over time in difference in caries
scores between fluoridated and non-fluoridated areas is due in part to the increased availability of
fluorides in non-fluoridated areas, as in toothpaste and other vehicles for fluorides" (USPHS,
1991, p. 35).
The Subcommittee did not use explicit criteria for assessing the quality of studies, instead addressing
threats to validity by examining and excluding alternative explanations for study results (USPHS, 1991,
pp. 26-28).
In 2000, a systematic review of the literature on the effectiveness of fluoridation conducted for the British
National Health Services by the Center for Reviews and Dissemination at the University of York
published their results. The independent panel of experts established explicit search and selection criteria
for inclusion of research on community water fluoridation conducted between 1966 and February 2000 in
industrialized countries. The review included only studies presenting both baseline and follow-up data on
child caries per tooth (DMFT) in two communities with different levels of fluoride in drinking water. A
total of 26 studies on the effect of water fluoridation on caries rates were found that met their minimum
design standards, five of them unpublished. Only one examined adults. Based on these 26 studies
completed between 1951 and 2000, they found sufficient evidence of moderate quality to conclude
"fluoridation of drinking water supplies does reduce caries prevalence" (NHS, 2000, p. 23). This amounted
to a (median) 14.6% increase in children without caries (range -5.0% to 64%) or a median 2.25 (range 0.5 to
4.4) fewer teeth per mouth having caries (McDonagh, et al., 2000). The evidence included both studies that
compared fluoridated and nonfluoridated communities (30 measures) as well as studies that compared never
fluoridated or still fluoridated communities with communities that stopped fluoridating the water supply (22
measures). "The best available evidence from studies following withdrawal of water fluoridation indicates
that caries prevalence increases, approaching the level of the low fluoride group" (NHS, 2000, p. xii). The
quality of evidence for this finding was rated as "of moderate quality" by the research panel.
The Fluoride Recommendations Work Group was assembled by the U.S. Centers for Disease Control and
Prevention (CDC) in the late 1990s to develop recommendations for using fluoride to prevent and control
caries. In 2001, they came to the following consensus regarding the current effectiveness of water
fluoridation in preventing decay in children:
"Initial studies of community water fluoridation demonstrated that reductions in childhood dental
caries attributable to fluoridation were approximately 50-60%. More recent estimates are lower,
18-40%.' This decrease in attributable benefit is likely caused by the increasing use of fluoride
from other sources, with the widespread use of fluoride toothpaste probably the most important.
Finding #I - The Effectiveness of Drinking Water Fluoridation in Preventing Caries 15
The diffusion or "halo" effect of beverages and food processed in fluoridated areas, but consumed
in non-fluoridated areas also indirectly spreads benefits of fluoridated water to non-fluoridated
communities. This effect lessens the differences in caries experience among communities" (CDC,
2001b, p. 11).
The group noted that quantifying the benefits of water fluoridation in adults is more complicated, but
found evidence to support effectiveness in this group as well (CDC, 2001b, p. 11). Using a system
developed to assess the quality of evidence regarding clinical preventive services (U.S. Preventive
Services Task Force, 1996), the group rated the evidence as II, on a scale from I (randomized controlled
trials which are considered the highest quality) to III (the lowest level as in the opinions of experts).
The Task Force on Community Preventive Services, a 15-member independent expert panel supported by
the CDC, the U. S. Department of Health and Human Services and other federal and public/private
partners, published the results of its systematic review of the evidence of effectiveness of selected
population-based interventions to prevent and control dental caries in 2001 (CDC, 2001 a, p. 8). Similar to
the British National Health Services panel, the group sought to review and evaluate all research on
community water fluoridation conducted between 1966 and December 2000 in the U.S. and other
industrialized countries. The process yielded 21 studies that met validity criteria. The median decrease in
dental caries upon starting or continuing community water fluoridation among the highest quality studies
was 29.1% (21 measures, range 110.5% decrease to 66.8% increase). The median increase in caries
following cessation of water fluoridation in the three qualifying studies was 17.9% (five measures, range
42.2% decrease to 31.7% increase). Two of the nine studies in the highest quality group showed negative
results (did not show an increase in caries after cessation of fluoridation). Reviewers concluded, "These
inconsistent estimates of effectiveness appear to have resulted from inadequate control of confounding
due to notably lower baseline caries prevalence in fluoridated compared with non-fluoridated areas"
(Truman, et al., 2002, p. 27). Based on this review, the Task Force made the following recommendation,
"Based on the evidence of effectiveness, the Taskforce strongly recommended community water
fluoridation" (CDC, 2001 a, p. 7).
Evidence of the Current Magnitude of Effectiveness
Over the last 30 years, the overall prevalence of caries has decreased dramatically (Table 1). All the
reviews above noted that the declining levels of caries in the U.S. and elsewhere translate into smaller net
differences in mean caries levels between fluoridated and nonfluoridated communities. The second
component of the effectiveness question the FTSG raised was, "What is the magnitude of caries protection
from water fluoridation in the current setting of widespread availability of other sources of fluoride?"
Comparing the summary estimates of effectiveness from a series of sequential comprehensive literature
reviews demonstrates the shrinking differences attributable to water fluoridation. In 1982, Murray and
Rugg-Gunn (1982) reviewed 95 water fluoridation studies conducted in 20 countries between 1945 and
1978. They found evidence that fluoridation reduced caries by 40-50% for primary teeth and 50-60% for
permanent teeth in this period (Murray & Rugg-Gunn, 1982). In 1989, Newbrun (1989) reviewed the
world literature from 1976 to 1987. He found 30-60% reductions in primary teeth and 30-40% reductions
in permanent teeth in adolescents and adults during this period. Figure 2 shows the decrease in mean
caries prevalence from 1979-80 to 1986-87 in eight and fifteen year olds from a national sample of school
children conducted by the NIDR. The mean percent reductions in caries rates between continuous
residents of fluoridated and nonfluoridated communities is also demonstrated (Brunelle & Carlos, 1990;
Brunelle & Carlos, 1982).
16 Report of the Fart Collins Fluoride Technical Study Group - April 2003
j Caries Prevalence (DMFS/Child), U.S. NIDR Surveys
10 _9-5
9 - - - -
8 - -
7
03 -
6 - - 5..58.:
5 _ - - ❑NF ~I
4 - - - - - ■F
2 1,37- 1 - - -
1 - _ D,79 0.64
0
8y/o-1980 8y/o-1987 15y/o-1980 15y/o-1987
Figure 2. Decrease in mean caries prevalence from 1979-80 to 1986-87 in eight
and fifteen year olds
Lewis and Banting (1994) began with Newbrun's review and updated it through 1992. They showed that
although the overall mean percent reductions between the years 1977-82 and 1983-91 were similar (27%
and 25% respectively), the absolute mean difference between fluoridated and nonfluoridated communities
in number of surfaces with caries dropped from 1.61 to 0.73 between these periods (Lewis & Banting).
They pointed out the sharp contrast between these results and the original community trials where
differences of about ten surfaces (five DMFTs) were seen in adolescents. The authors suggested that since
the diffusion of fluoride into nonfluoridated communities is impossible to control for, the effectiveness of
water fluoridation could no longer be determined (Lewis & Banting).
Two recent reviews specifically addressed the question of the current magnitude of effectiveness. First,
Dr. David Locker of University of Toronto conducted a systematic literature review of the effectiveness
of community water fluoridation spanning 1994 through November 1999, for the Public Health Branch,
Ontario Ministry of Health & First Nations and Inuit Health Branch, Health Canada. Twenty-nine
published studies were found in which optimally fluoridated communities were compared with concurrent
or historical controls (Locker, 1999). Twenty-five were weak "before-after" ecological study designs-
four were more robust cross-sectional studies. They examined the magnitude of the current caries
prevention effect using two of the more robust studies, both cross-sectional; one based on the 1986-87
National Survey of U.S. School Children and the other from Australia. While the U.S. study found water
fluoridation reduced caries by 25%, the absolute difference in mean caries prevalence between those
living in fluoridated and those living in nonfluoridated communities was 1.14 surfaces in deciduous
(baby) teeth and 0.55 surfaces in permanent teeth (Heller, Eklund, & Burt, 1997). In South Australia, the
differences were smaller, ranging from 0.12 to 0.3 surfaces in permanent teeth (Slade, Davies, Spencer, &
Stewart, 1995). The reviewers concluded that caries reductions are now relatively small in absolute terms,
particularly in permanent teeth and that water fluoridation explains only a small part of the variation in
caries experience between children. The authors concluded:
"Given the weaknesses in design and the methodological flaws to which many of the studies were
subject, the data from these more recent studies must be treated with some caution. While the
balance of evidence overall suggests that water fluoridation does reduce caries experience, the
magnitude of the effect is subject to a degree of uncertainty but is unlikely to be large in absolute
terms" (Locker, 1999, p. 33).
Finding #I The Effectiveness of Drinking Water Fluoridation in Preventing Caries 17
The NHS Center for Reviews and Dissemination (2000) analyzed studies conducted since 1974 to
examine the effect of water fluoridation over and above other sources of fluoride. Of the ten studies that
met their inclusion criteria, seven examined the discontinuation of fluoride. Although two of these studies
(Kunzel & Fischer, 1997; Maupome, Clark, Levy, & Berkowitz, 2001) found that mean levels of caries
did not increase after the fluoridated community stopped fluoridating, the remainder showed that there
was a greater increase in caries levels in the fluoridated-ended communities than in the controls. The
panel concluded, "a beneficial effect of water fluoridation was still evident despite an assumed exposure
to non-water fluoride in the populations studied" (NHS, 2000, p. xii). The quality of evidence for this
finding was rated as "of moderate quality" by the research panel.
The Medical Research Council of the British Health Service established a Working Group to consider
what further research is needed to improve knowledge about water fluoridation and health, following the
release of the NHS review. The Working Group report published in September 2002 specifically
recommended more research of the effects of water fluoridation against a background of widespread use
of fluoride toothpaste, while controlling for age, social class, ethnic group, sugar consumption and use of
other discretionary fluorides.
Studies of the Effectiveness of Community Water Fluoridation in Adults
Locker also reviewed recent studies of effectiveness of community water fluoridation in adults (Locker,
1999, p. 31). Four studies published since 1990 met inclusion criteria. All four studies found substantial
reductions in coronal and root caries in adults living in fluoridated as compared with nonfluoridated
communities. Two of the studies had prospective cohort designs (a design with fewer threats to validity).
Grembowski, Fiset and Spadafora (1992) tracked caries rates in 972 Washington state employees and
spouses, aged 20 to 34 years, in two fluoridated communities and a nonfluoridated community. After
controlling for an extensive array of variables, they found that drinking water fluoridation reduced DMFS
by 0.35 surfaces per year of fluoridation exposure (Grembowski, et al.). For 18 months, Hunt, Eldredge and
Beck (1989) prospectively followed seniors who were long-term residents of fluoridated and nonfluoridated
communities. They found that the risk of developing caries was 20% less on the crowns of teeth and 27%
less on root surfaces in those with long-term residence in fluoridated communities (Hunt, et al.).
Considering that the population is aging, that tooth retention has increased in adults in recent decades
(CDC, 2001b, p. 11), and that root surface exposure due to gingival recession renders adults particularly
susceptible to root caries, the question of the effectiveness of water fluoridation in prevention of caries in
adults is particularly important. The small number of studies examining this population, while consistent,
cannot provide robust proof of effectiveness. In addition to Locker, the CDC, the U.S. Task Force for
Community Preventive Services, and the British Medical Review Council (see below) all identified this
as an area where future research should be focused (Locker, 1999; CDC, 2001a; Truman et al., 2002;
Medical Research Council [MRC], 2002).
Fluoridation-Ended Sites in Which No Caries Increases Werd Found
While virtually all studies examining the initiation of fluoridation demonstrate caries reductions compared
to nonfluoridated communities, recent studies in which the impact of ending fluoridation has been
measured have yielded mixed results. The NHS review and the review by the Task Force of Community
Preventive Services both examined this evidence and concluded that mean caries rates generally increase
when fluoridation is stopped. The Task Force review estimated the relative increase at 17.9% based on the
highest quality studies (CDC, 2001a). However each review included examples of communities in which
caries rates did not increase. Studies demonstrating these inconsistent results are frequently cited by
opponents of fluoridation. For this reason, and because the impact of stopping fluoridation is of particular
interest to the current policy question in Fort Collins, the FTSG chose to examine these studies in detail.
18 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Among the 14 recent studies (completed after 1985) in which water fluoridation was discontinued, nine
showed an increase in caries rates. Five found that caries levels had either remained stable or dropped
after fluoridation ended. To the extent that these study settings are generalizable to Fort Collins, it is
important to detennine whether or not their results can be explained. If explanations are wanting, they
raise the level of uncertainty of the FTSG's findings. A brief review of each of these studies follows.
Two ecological time-series studies published in 1997 and 2000 found that caries prevalence among
children decreased in four fluoridation-ended sites in former East Germany (Kunzel & Fischer 1997;
Kunzel, Fischer, Lorenz, & Bruhmann, 2000). In these four industrial towns, systematic surveys of caries
prevalence in children have been conducted every two to four years since fluoridation began (1959-1972).
During the first three decades of these surveys, the level of caries prevalence was strictly correlated with
the availability of an optimal fluoride concentration in the drinking water. Water fluoridation was
followed by a decrease of caries, and interruptions in fluoridation were followed by increasing caries
levels. A different trend was noted in the 1990s. Contrary to an expected caries increase there was a
consistent statistically significant decrease across virtually all ages (ages 6-15) in surveys of life-long
residents conducted three to eight years after cessation of fluoridation. These two studies raise important
questions, but both have serious design flaws. First, the authors note that the reunification in Germany in
1990 led to "dramatic social transformation," including not only cessation of water fluoridation, but also
"complete change" in provision of preventive dental care and oral health services. Dental services and
school dental services were largely privatized (though coverage remained comprehensive), dentist
utilization increased, fissure sealants were introduced, fluoridated salt was introduced, use of fluoridated
toothpastes increased from 15% to 88%, use of topical fluorides and antibiotics increased and sugar
consumption decreased, all within several years (Kunzel, Fischer, Lorenz, & Bruhmann). Because the
design of the 1997 study was ecological, the authors were not able to control for these important
intervening factors. In the 2000 study, some of these factors were measured in individual subjects, but
there was no concurrent control community, so the net impact could not be estimated. Both studies were
also flawed by changes in methods of subject selection before and after cessation of fluoridation, lack of
blinding, and measurement issues. The authors conclude:
"The causes for the changed caries trend were seen on the one hand in improvements in attitudes
towards oral health behavior and, on the other hand, to the broader availability and application of
preventive measures (F-salt, F-toothpastes, fissure sealants etc.). There is, however, still no
definitive explanation for the current pattern and further analysis of future caries trends in the
formerly fluoridated towns would therefore seem to be necessary" (Kunzel, Fischer, Lorenz, &
Bruhmann, 2000, p. 382).
Further corroboration of this apparent phenomenon was noted in a two-community ecological before-after
study of caries in 6-15 year olds conducted in Finland (Seppa, Karkkainen, & Hausen, 1998). The city of
Kuopio was fluoridated (1.0 mg/L) in 1959 and discontinued the practice in 1992. The comparison town
of Jyvaskyla was not fluoridated (0.1 mg/L). The percentage of children using fluoridated toothpaste was
85% in both towns. "In 1995, a decline in caries was seen in the two older age groups in this
nonfluoridated town. In spite of discontinued water fluoridation, no indication of increasing trend of
caries could be found in Kuopio" (Seppa et al., p. 256). However, once Kuopio stopped fluoridating there
was a slower decline in caries so that by three years post-fluoridation the relative advantage of Kuopio
over Jyvaskyla in terms of caries rates had disappeared. This was in spite of more frequent use of other
fluoride measures, including fluoride tablets in Kuopio (Seppa, p. 261). It is important to note that
Finland has comprehensive prevention-oriented dental services for all children and adolescents, and the
use of fluoride toothpaste, varnishes and tablets are common.
La Salud, Cuba was fluoridated in 1973. Water fluoridation at 0.8 mg/L ceased in 1990. "Toothbrushes
were scarce, F-toothpastes were not available, and the sugar consumption was high" (Kunzel & Fischer,
2000), yet, in 1997 there was a significant decrease in caries levels in the oldest age group (12 and 13 yr.
Finding #I - The Effectiveness of Drinking Water Fluoridation in Preventing Caries 19
olds) and levels in the younger ages remained stable. This before-after survey had no control group so no
distinction can be made between what was due to secular trends and what was due to cessation of
fluoridation. Perhaps most important, a fluoride mouth rinsing program was initiated in the schools of La
Salud soon after cessation of water fluoridation (Kunzel & Fischer, 2000).
A study conducted in two communities in British Columbia, a fluoridated-ended and a still fluoridated
site, included both a time-series analysis and a prospective cohort analysis of 8-11 and 14-17 year old
children at 1'/z and 31/Z years after the study community stopped fluoridating in 1992 (Maupome, Clark,
Levy, & Berkowitz, 2001; Maupome, Shulman, Clark, Levy, & Berkowitz, 2001). The prevalence study
found that while caries rates stayed the same in the still fluoridated community, they dropped significantly
in the fluoridated-ended community over the three years. However, overall caries prevalence rates in 8
and 11 year olds were still 52% and 35% lower in the still fluoridated community in the final survey.
Caries incidence rates (new cases) were also 20% lower in the still fluoridated conununity. This suggested
that confounding by other factors might account for this unexpected drop in caries. After adjusting for
socio-economic status, age, frequency of mouth washing and tooth brushing with fluoridated products,
exposure to fluoride supplements and overall snacking practices, the researchers noted higher caries
scores for at-risk surfaces (erupted and unsealed surfaces) in the fluoridation-ended group. The
researchers also tracked progression and reversal of "white spots," the surface lesions that lead to cavities.
Comparing children/adolescents in the two communities, the odds were more than two times greater
(odds ratio was 2.42, 95% confidence interval was 1.97-2.98) that an early smooth surface "white spot"
would progress to a cavity in the fluoridation-ended community than in the still fluoridated community
(Maupome, & Shulman, et al., 2001). The researchers noted that, together with increasing use of sealants
in both communities, there appeared to be earlier and more common fillings applied in the fluoridation-
ended site, and that this might account for reductions in active caries in both communities. This study
demonstrates the complicated shifts in caries and caries treatment experience following cessation of
fluoridation in a relatively affluent community with low baseline caries risk. Like the studies above,
caries prevalence decreased over time in the fluoridation-ended site, yet in this well designed study, the
researchers found that the risk of caries progression was greater once other factors were controlled for.
In spite of their respective design flaws, these five studies raise important issues: First, there are multiple
factors that determine caries incidence in a community. In some contexts, community water fluoridation's
contribution to caries prevention and reversal is over-shadowed by other factors such as wide-spread use
of fluoridated toothpaste combined with a high standard of living, universal access to dental care, or
school-based prevention programs. When fluoridation was stopped in these contexts, mean caries levels
did not increase, though individuals who did not receive enough fluoride may have suffered. Second, the
act of suspending water fluoridation may provide the impetus to change personal oral health behaviors or
to initiate other public oral health programs, as it did in each of these settings. These changes can prevent
expected increases in caries. Third, differences in caries rates between exposed and non-exposed
individuals have narrowed to the point where biases introduced by weak study designs could be large
enough to mask a true difference in caries measures or demonstrate a difference when one doesn't exist.
Fourth, there may be other factors, as yet unidentified, that contributed to caries rates not increasing after
stopping water fluoridation in these cities.
Perhaps the most important difference between the settings reviewed and those in Fort Collins (and the
U.S. as a whole) is the lack of universal access to dental care and the lack of substantive school-based
prevention programs locally (see Finding 43).
Gaps in Knowledge
The Task Force for Community Preventive Services summarized the gaps in knowledge regarding
community water fluoridation effet;tiveness in their 2002 review (Truman, et al., 2002, p. 32):
20 Report of the Fort Collins Fluoride Technical Study Group - April 2003
• "What is the effectiveness of laws, policies, and incentives to encourage communities to start or
continue water fluoridation?"
• "What is the effectiveness of community water fluoridation in reducing socioeconomic or racial
and ethnic disparities in caries burden?"
• "What is the effectiveness of community water fluoridation among adults (aged ?18 years)?"
• "What, if any, are the effects of the increasing use of bottled water and in-home water filtration."
• "How effective is community water fluoridation in preventing root-surface caries?"
The Medical Research Council added the need for more studies designed to estimate the impact of
community water fluoridation in children ages 3-15 in today's environment of widespread use of fluoride
dentifrices (MRC 2002, p. 18). In reviewing the York Study, the Medical Research Council noted that:
"The York Review concluded that water fluoridation was effective, but the authors were reluctant
to estimate the likely impact in today's environment. Therefore, to inform policy, future research-
including economic evaluation- should determine the short-term impacts of water fluoridation on
dental caries (i.e..within four years of implementation), though there would be advantages in
extending studies to ten years and beyond in order to capture more fully the effects on the
permanent dentition" (MRC, 2002, p. 19).
A member of the FTSG raised a concern that exposure to water fluoridation may delay eruption of teeth
and this could account for apparent effectiveness of caries prevention in children. The FTSG was not able
to find credible evidence to support this concern.
FINDINGS: The Effectiveness of Drinking Water Fluoridation in
Preventing Caries (Cavities)
The weight of the evidence suggests that there is caries reduction in populations exposed to water
fluoridation at or near an optimal level. The primary mode of action of fluoride in preventing caries
(cavities) is its topical action on the surface of the teeth; systemic action from ingestion is now thought to
play a minor role. This benefit amounts to a relative caries reduction of 25% and an absolute prevalence
difference of 1.14 surfaces with caries in primary teeth and 0.5 surfaces with caries in permanent teeth in
children according to.the most recent U.S. surveys of schoolchildren. Among the four studies of caries
prevention in adults, the most recent study showed that community water fluoridation reduced surfaces
with caries by 0.35 surfaces per year of fluoride exposure. It appears that community water fluoridation is
effective in all age groups in preventing dental caries. The benefit of drinking water fluoridation decreases
as individuals in the population receive fluoride from other sources (e.g., toothpastes, dental care, etc.).
Even with the limitations of some of the studies, there appears to be a net benefit in caries reduction from
drinking water fluoridation over and above that from toothpaste and other sources of fluoride. Among the
14 recent studies (completed after 1985) reviewed in which water fluoridation was discontinued, nine
showed an increase in caries rates. Five communities (all of them in other countries) that suspended water
fluoridation did not find that caries rates increased. It is uncertain to what degree changes in oral health
behaviors, introduction of new preventive programs and increased delivery of professional treatments in
response to cessation of fluoridation can account for these findings. Since these studies were conducted in
foreign communities in which there was socialized dental care and school-based oral health programs,
their results may not apply to Fort Collins.
Finding #1 - The Effectiveness of Drinking Water Fluoridation in Preventing Caries 21
Reference List
Brunelle, J.A. & Carlos, J.P. (1982). Changes in the prevalence of dental caries in U.S. schoolchildren,
1961-1980. Journal of Dental Research, 61, 1346-1351.
Brunelle, J.A. & Carlos, J.P. (I990). Recent trends in dental caries in U.S. children and the effect of water
fluoridation. Journal of Dental Research, 69, 723-727.
Centers for Disease Control and Prevention. (I 999a). Fluoridation of drinking water to prevent dental
caries. Morbidity and Mortality Weekly Report, 48(41), 933-940.
Centers for Disease Control and Prevention. (1999b). Water fluoridation and costs of Medicaid treatment
for dental decay - Louisiana, 1995-6. Morbidity and Mortality Weekly Report, 48(34), 753-757.
Centers for Disease Control and Prevention. (2001 a). Promoting oral health: interventions for preventing
dental caries, oral & pharyngeal cancers, and sports-related craniofacial injuries: a report on
recommendations of the task force on community preventive services. Morbidity and Mortality
Weekly Report, RR-21.
Centers for Disease Control and Prevention. (2001b). Recommendations for using fluoride to prevent and
control dental caries in the United States. Morbidity and Mortality Weekly Report, RR-14.
Committee to Coordinate Environmental Health and Related Programs, United States Public Health
Service. (1991). Review of Fluoride: Benefits and Risks: Report of the subcommittee on fluoride
of the EHPC. United States Public Health Service, Department of Health and Human Services.
Driscoll, W.S., Horowitz, H.S., Meyers, R.J., Heifetz, S.B., Kingman, A., & Zimmerman, E.R. (1986).
Prevalence of dental caries and dental fluorosis in areas with negligible, optimal, and above-
optimal fluoride concentrations in drinking water. Journal of the American Dental Association,
113(1), 29-33. [erratum appears in Journal of the American Dental Association (1986)
113(3), 370.]
Expert Panel for Water Fluoridation Review, City of Calgary. (1998). Report of the expert panel for water
fluoridation review appointed by the standing committee on operations and environment.
Calgary, Canada.
Featherstone, J.D. (1999). Prevention and reversal of dental caries: role of low level fluoride. Community
Dental and Oral Epidemiology, 27, 131-40.
Grembowski, D., Fiset, L., & Spadafora, A. (1992). How fluoridation affects adult dental caries. Journal
of the American Dental Association, 123(2), 49-54.
Heller, K.E., Eklund, S.A., & Burt, B.A. (1997). Dental caries and dental fluorosis at varying water and
fluoride concentrations. Journal of Public Health Dentistry, 57(3), 136-143.
Hunt, R.J., Eldredge, J.B., & Beck, J.D. (1989). Effect of residence in a fluoridated community on the
incidence of coronal and root caries in an older adult population. Journal of Public Health
Dentistry, 49(3), 138-141.
Kaste, L.M., Selwitz, R.H., Oldakowski, R.J., Brunelle, J.A., Winn, D.M., & Brown, L.J. (1996). Coronal
caries in the primary and permanent dentition of children and adolescents 1-17 years of age:
United States, 1988-1991. Journal of Dental Research. 75 Spec No, 631-641.
22 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Kunzel, W. & Fischer, T. (1997). Rise and fall of caries prevalence in German towns with different F
concentrations in drinking water. Caries Research, 31(3), 166-173.
Kunzel, W. & Fischer, T. (2000). Caries prevalence after cessation of water fluoridation in La Salud,
Cuba. Caries Research, 34(1), 20-25.
Kunzel, W., Fischer, T., Lorenz, R., & Bruhmann, S. (2000). Decline of caries prevalence after the
cessation of water fluoridation in the former East Gennany. Community Dentistry & Oral
Epidemiology, 28(5), 382-389.
Lewis, D.W. & Banting, D.W. (1994). Water fluoridation: current effectiveness and dental fluorosis.
Community Dentistry & Oral Epidemiology, 22(3), 153-158.
Locker, D., (1999). Benefits and Risks of Water Fluoridation - An update of the 1996 Federal-Provincial
Sub-committee Report. University of Toronto, Canada.
Maupome, G., Clark, D.C., Levy, S.M., & Berkowitz, J. (2001). Patterns of dental caries following the
cessation of water fluoridation. Community Dentistry & Oral Epidemiology, 29(1), 37-47.
Maupome, G., Shulman, J.D., Clark, D.C., Levy, S.M., & Berkowitz, J. (2001). Tooth-surface
progression and reversal changes in fluoridated and no-longer-fluoridated communities over a 3-
year period. Caries Research, 35(2), 95-105.
McDonagh, M.S., Whiting, P.F., Wilson, P.M., Sutton, A.J., Chestnutt, I., Cooper, J., et al. (2000).
Systematic review of water fluoridation. British Medical Journal, 321(7265), 855-859.
Medical Research Council. (2002). Working Group Report: Water Fluoridation and Health. London, UK:
Medical Research Council.
Murray, J.J. & Rugg-Gunn, A.J.I. (1982). In: Derrick, D.D. (Ed.) Fluorides in Caries Prevention. Bristol,
UK: John Wright.
Newbrun, E. (1989). Effectiveness of water fluoridation. Journal of Public Health Dentistry, 49(5 Spec
No), 279-289.
NHS Centre for Reviews and Dissemination, University of York. (2000). A Systematic Review of Public
Water Fluoridation. York, UK: York Publishing Services Ltd.
Ripa, L.W. (1993). A half century of community water fluoridation in the United States: review and
commentary. Journal of Public Health Dentistry, 53(1), 17-44.
Seppa, L., Karkkainen, S., & Hausen, H. (1998). Caries frequency in permanent teeth before and after
discontinuation of water fluoridation in Kuopio, Finland. Community Dentistry & Oral
Epidemiology, 26(4), 256-262.
Slade, G.D., Davies, M.J., Spencer, A.J., & Stewart, J.F. (1995). Associations between exposure to
fluoridated drinking water and dental caries experience among children in two Australian states.
Journal of Public Health Dentistry, 55(4), 2.18-228.
Sutton, P. (1960). Fluoridation: Errors and Omissions in Experimental Trials. Melbourne University
Press. (2nd Ed.)
Truman, B.I., Gooch, B.F., Sulemana, I., Gift, H.C., Horowitz, A.M., & Evans, C.A. (2002). Reviews of
evidence on interventions to prevent dental caries, oral and pharyngeal cancers, and sports-related
craniofacial injuries. American Journal of Preventive Medicine, 23(1 Suppl), 21-54.
Finding #1 - The Effectiveness of Drinking Water Fluoridation in Preventing Caries 23
U.S. Department of Health and Human Services. (2000). Oral Health in America: A Report of the
Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, National
Institute of Dental and Craniofacial Research, National Institutes of Health.
U.S. Preventive Services Task Force. (1996). Guide to clinical preventive services. (2nd ed.) Baltimore,
MD: Williams & Wilkins.
24 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Finding #2 - The Risk of Drinking Water Fluoridation
In this section, the Fluoride Technical Study Group (FTSG) summarizes the evidence from toxicologic
and epidemiologic studies that addresses the potential for community water fluoridation to cause adverse
health outcomes in the community. The major outcomes considered include cancer, effects on bone,
dental enamel fluorosis, effects on the immune system and effects on thyroid function. While the focus of
this evaluation is on potential risks from the city's practice of drinking water fluoridation at lmg/l, the
risks from total fluoride dose including other sources is also considered.
Total Exposure to Fluoride
The FTSG evaluated total consumption of fluoride from all sources so that the likelihood of health risks
from fluoridation could be evaluated for the appropriate potential total dose, not just the dose from water
fluoridation. The sources of fluoride intake for the U.S. population are primarily water, food, and dental
products (Tables 4 and 5). Although fluoride exposure is generally greater in areas with fluoridated water
than in areas with nonfluoridated or low-fluoridated water, populations in both areas are exposed to
fluoride from food sources, drinking water, processed beverages and dental products. According to the
US Public Health Service:
"In optimally fluoridated areas, most of the estimated daily intake of fluoride for children and adults is from
drinking water, beverages and food. In low-fluoride or non-fluoridated areas, children can receive their
highest proportion of daily intake from fluoride supplements and dentifrice[see Table 3]. The daily intake
of most adults is about equally divided among food, drinking water, beverages, and mouthrinses [see Table
4 below]." (Committee to Coordinate Environmental Health and Related Programs, USPHS [USPHS],
1991, p. 15).
Dietary sources of fluoride (other than drinking water) are outlined in Table 1.
Table 1
Fluoride Concentrations (m_glL or Kg) in Food (adapted from USPHS, Table 5, p.11)
Foods (Note A) Mean (mg/L or Kg) Standard Deviation Range
Dairy Products 0.25 0.38 0.02-0.82
Meat Fish & Poultry 0.22 0.15 0.04-0.51
Grain & Cereal Products 0.42 0.40 0.08-2.01
Potatoes 0.49 0.26 0.21 -0.84
Leafy Vegetables 0.27 0.25 0.21-0.84
Legumes 0.53 0.05 0.49-0.57
Root Vegetables 0.38 0.11 0.27-0.48
Fruits 0.06 0.03 0.02-0.08
Oils & Fats 0.25 0.15 0.02-0.44
Sugar and Adjuncts 0.28 0.27 0.02-0.78
Nonclassifiable Foods 0.59 0.19 0.29-0.87
Note: The foods were ready to eat or prepared for eating. When preparation required the use of water (e.g. preparing juice
from concentrate or boiling vegetables), the local water was used which contained 1 mg/L (1 ppm) of fluoride.
Nonclassifiable foods included certain soups and puddings, among other items.
Most foods have fluoride concentrations below 0.5 mg/liter or kg (Dabeka & Mckenzie, 1995). Among
beverages the highest amounts of fluoride are reported in teas. Due to the ability of tea leaves to
Finding #2: The Risk of Drinking Water Fluoridation 25
concentrate fluoride, brewed tea contains fluoride ranging from I to 6 mg/liter depending on amount,
brewing time and fluoride concentration in water (USPHS, 2000, p. 294).
Intake from fluoridated dental products sometimes exceeds that from diet, particularly in young children
who swallow toothpaste due to poor control of the swallowing reflex. An average of about 0.3 mg of
fluoride is introduced with each brushing in young children (USPHS, 2000, p. 296). In communities with
low levels of fluoride in the water supply, oral fluoride supplements are recommended by the American
Academy of Pediatrics, American Dental Association, and the American Academy of Family Physicians.
Table 2 shows the 1995 recommended supplement endorsed by these associations. No supplement is
recommended for children under six months of age.
Table 2
Recommended Fluoride Supplementation (mg/day) for Children of Different Ages at Different
Drinking Water Fluoride Concentrations
Fluoride Supplements
Drinking Water Child Age 0 to 6 Child Age 6 to 36 Child Age 3 to 6 Child Age 6 to
Fluoride Concentration Months Months Years 10 Years
<0.3 ppm Not recommended 0.25 mg/day 0.5 mg/day 1.0 mg/day
0.3-0.6 ppm Not recommended Not recommended 0.25 mg/day 0.5 mg/day
>0.6 ppm Not recommended Not recommended Not recommended Not recommended
Reference
(1) American Academy of Pediatrics, (1995) Committee on Nutrition, Pediatrics, 95, 777; also endorsed by the American Dental
Association and the American Academy of Family Physicians.
According to the Institute of Medicine:
"Based on the 1986 National Health Interview Survey (NHIS) data, it is estimated that 15 percent
of children in the United States up to age 5 years and 8 percent of children 5 to 17 years old use
dietary fluoride supplements. Fluoride supplements are rarely prescribed for adults" (Committee
on the Scientific Evaluation of Dietary Reference Intakes, Institute of Medicine [IOM], 2000, p.
295).
Tables 3 and 4 illustrate the ranges of fluoride intake (mg/day) for children and adults from all sources in
areas with water fluoridated at three different levels, including I mg/L fluoride. The ranges presented are
estimated total intakes extrapolated from published studies and are not derived from data measured in
individuals. The maximum values are derived by summing the highest intakes reported in published
literature for each type of ingested fluoride source. The estimates also assume that adults in both
optimally fluoridated and non-fluoridated areas use fluoride mouth-rinse twice daily.
26 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Table 3
Estimated Daily Fluoride Intake of Child Weighing 20kg (44 lbs)a (adapted from USPHS, 1991,
Table 10, p. 16)
FI Containing Fluoride F S d .
Fluoride intake from geveragesb in Dentifrices in upplements in Estimated Total
in Water Food in mg/day mg/day Intake in mg/day
(mg/L) (mg/kg/day) (m g/day g/day) (mg kdday) (mg/kg/day) (mg/kg/day)
X0.3 0.15-0.3 0.1-0.3 0.2-1.2 0.50 0.95-2.3
(0.007-0.015) (0.005-0.015) (0.01-0.06) (0.025) (0.047-0.115)
0.7-1.2 0.4-0.6 0.3-1.8 0.2-1.2 Not recommended 0.9-3.6
[0.02-0.03] [0.015-0.09] [0.01-0.06] [0.045-0.18]
>2.0 1.0-2.0 0.6->3.0 0.2-1.2 Not recommended 1.8->6.2
[0.05-0.10] [0.03-0.15] [0.01-0.06] [0.09-0.31]
a Calculations based on child weighing 20 kg (44 lbs)
b Based on ranges of data extrapolated from various literature sources by PHS.
C Assumed that dentifrice used twice daily
d Assumed that dental fluoride supplement taken daily
Table 4
Estimated Daily Fluoride Intake of Adult Weighing 50 kg (110 /bs)a
(adapted from USPHS, Table 11, p. 17)
FI Containing Fluoride
Fluoride Intake F Mouthrinse° Estimated Total
from geveragesb in Dentifrices° in
in Water Food in mg/day mg/day mg/kg s in mg/kg Intake in mg/kg
(mg/L) (mg/kg/day) (mg kg/day) (mg/kg/day) (mg/kg/day) (mg/kg/day)
<0.3 0.2-0.8 0.1-0.7 0.018-0.145 0.56 0.88-2.20
(0.004-0.016) (0.002-0.014) (0.0004-0.003) (.010) (0.016-0.40)
0.7-1.2 0.4-2.7 0.6-3.2 0.018-0.145 0.56 58-6.6
[0.008-0.54] [0.012-0.064] [0.0004-0.003] [0.01] [0.03-0.13]
>2.0 1.2-3.4 0.9->3.5 0.018-0.145 Not recommended 2.1->7.05
[0.02-0.07] [0.018->0.07] [0.0004-0.003] [0.04->0.14]
a Calculations based on adult weighing 50 kg (110 lbs)
b Based on ranges of data extrapolated from various literature sources by PHS.
c Assumed that dentifrice and mouth-rinse are used twice daily
According to the Institute of Medicine:
"Ten independent U.S. and Canadian studies published from 1958 to 1987 have shown that
dietary fluoride intakes by adults range from 1.4 to 3.4 mg/day in areas where the water fluoride
concentration was 1.0 mg/liter. In areas where the water fluoride concentration was less than 0.3
mg/liter, the daily intakes ranged from 0.3 to 1.0 mg/liter day" (IOM, 2000, p. 293).
Finding #2: The Risk of Drinking Water Fluoridation 27
Table 5 shows the average total daily intake of fluoride by age.
Table 5
Average Intake of Dietary Fluoride by Age
(Whitford, 1994, p. 6)
Age Mg F/Day Mg F/Kg/Day Reference
0-6 months
Breast-fed <0.01 <0.003 Ekstrand et at., 1984
Formula-fed:
Ready-to-feed <0,4 <0.13 Johnson and Bawden, 1987
Reconstituted' ca. 1.0 <030 McKnight-Hanes et al., 1988
6 months 0.2-0.5b 0.03-0.07 Ophaug et al., 1980a
2 years 0.3-0.66 0.02-0.05 Ophaug et al., 1980b
Adult 1.2 0.016-0.022` Singer et al., 1980
1.8 0.023-0.033` Taves, 1983
2.2 0.029-0.040` SanFilippo & Battisonte, 1971
a Reconstituted with water fluoridated at t ppm.
b Lower value is for nonfluoridated water. Higher value is for optimally fluoridated water.
c Range calculated for persons with body weights of 75 kg and 55 kg whose drinking water is
optimally fluoridated.
Dietary reference intakes established by the Institute of Medicine (IOM, 2000) include adequate intake
levels set for all children and adults at 0.05 mg/kg/day. For infants newborn to six-months old the
recommended amount (based on the amount found in breast milk) is 0.01 mg/day. The upper limit set to
protect against moderate dental fluorosis is 0.1 mg/kg/day for all ages. This upper limit of 0.7 mg/day,
assuming a seven kg infant weight, can be exceeded in optimally fluoridated water communities when
water of 1.0 mg/l of fluoride is used to make reconstituted formula and fed to infants less than six months
old. The upper limit set for infants 7 to 12 months is 0.9 mg/day. The Institute of Medicine set the upper
limits for children age 1 to 3 at 1.3 mg/day and age four to eight at 2.2 mg/day based on reference weights
of 13 kg and 22 kg respectively.
The FTSG noted that for children six months to six years, total fluoride consumption from food and
beverages nearly equals the recommended adequate intake levels of 0.05 mg/kg/day. If excess water or
beverages are consumed or fluoridated toothpaste is inappropriately eaten, fluoride levels may exceed the
0.1 mg/kg/day upper limit standard and may cause dental fluorosis. Repeated over-ingestion during the
formative years of tooth development (three months to six years) may result in varying degrees of dental
fluorosis on a dose-dependent scale. After age six to seven, all anterior (front) teeth have completed their
enamel formation, and after age eight, all but the wisdom teeth crowns are formed. The risk of moderate
dental fluorosis is low because of the low likelihood of exposures at the extremes of the range presented
in Table 3. The estimated upper range of the total intakes in Table 3 exceeds the values set by the Institute
of Medicine to be protective of moderate dental fluorosis. The upper limit established for children older
than 8 years and adults is 10 mg/day. This level is not exceeded at optimal levels of water fluoridation.
Several regulatory bodies have determined thresholds for safe daily intake of fluoride based on potential
adverse effects (tooth or bone effects). The Agency for Toxic Substances and Disease Registry
(ATSDR) has set a chronic Minimal Risk Level (MRL) for ingestion of fluoride at 0.05 mg/kg/day
(ATSDR: http://www.atsdr.cdc.pov/mrls.htmt). The MRL is an estimate of the daily human exposure to a
hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over
28 Report of the Fort Collins Fluoride Technical Study Group - April 200.3
a specified duration of exposure. The ATSDR based this on a lowest observed adverse event level for
increased fracture rates (see "Bone Effects" section below), and divided it by a "safety factor" of 10. The
U.S. EPA has established a "reference dose," a standard similar to the MRL, of 0.06mg/kg/day, based on
a "no-observed adverse effect level" for mottling of the teeth (see "Enamel Fluorosis" section below). The
FTSG noted that there is a narrow "margin of safety" when comparing average daily intake of fluoride in
Table 5 with these levels.
Fluoride Exposure Uncertainties
The gaps in knowledge regarding total fluoride exposure from all sources are captured in the following
summaries:
In the "Tier One" literature, the Medical Research Council of Great Britain noted several uncertainties
with regard to total fluoride exposure estimates and the impacts of total exposure uncertainties on health
effects assessments cited as follows:
"As previously recounted, developments since 1960 have altered the general pattern of fluoride
exposure and may have created a new situation in the population at large, both with respect to
total exposure and the main sources of exposure. There are therefore several deficiencies in the
existing body of evidence when evaluating effects relating to fluoride exposure, and other
questions that need to be addressed: The effects of fluorides are probably related to total
exposure, not just fluoride in drinking water. There are very few data relating total fluoride
exposure to health effects" (Medical Research Council (MRC}, 2002, p. 14).
In general, the absorption of fluoride ion into the body (called "bioavailability") is high, however it depends
to a certain extent on the nature of the vehicle it is ingested with. According to the Institute of Medicine's
Dietary Reference Intake Guide, "if it is ingested with milk, baby formula, or foods, especially those with
high concentrations of calcium or certain other divalent or trivalent ions that form insoluble compounds,
absorption may be reduced by 10-25%" (IOM, 2000, p.291).
The Medical Research Council of Great Britain recommends the following:
"New studies are required to investigate the bioavailability and absorption of fluoride from
naturally fluoridated and artificially fluoridated drinking water, looking also at the impact of
water hardness. This is particularly important because if the bioavailability is the same, many of
the findings relating to natural fluoride can also be related to artificial fluoridation.
Further attempts should be made to calculate lifetime intakes of fluoride, using both
urinary and ingestion data, and to determine the relative contribution of fluoride in artificially
fluoridated water to total fluoride uptake. If the bioavailability of artificial and natural fluoride are
found to be the same, then studies on people who have lived in naturally high fluoride areas could
be informative" (MRC, 2002, p. 15).
Other observations have appeared in the peer-reviewed literature and in the summaries of review panels.
"Investigators seeking to examine possible relations between fluoride intake and biological
effects or health outcomes, such as dental fluorosis or the quality of bone or its strength, need to
be aware of the complex situation that exists today. It is no longer feasible to estimate with
reasonable accuracy the level of fluoride exposure based simply on the concentration of the ion in
the drinking water" (Whitford, 1994, pp. 7-8).
"There was considerable concern amongst many Taskforce members that water fluoridation could
increase the total intake of fluoride in excess of a safe level for babies and young childrel►. The
evidence relating to what constituted a safe or a toxic dose of fluoride was uncertain and confusing.
Finding #2: The Risk of Drinking Water Fluoridation 29
A majority of Taskforce members were concerned that the margin of safety between a safe and
toxic dose may not be sufficiently wide" (The Lord Mayor's Taskforce on Fluoridation, 1997, p. 89)
FINDINGS: Total Fluoride Exposure
Total fluoride exposure must be considered when evaluating health effects. The amount of total fluoride
ingested will vary between individuals and is not precisely known. The FTSG review of the literature
finds that likely total exposure values for children older than six months living in communities with water
fluoridated at up to 1.2 mg/L (ppm) do not exceed the upper limit set to be protective of moderate dental
fluorosis by the Institute of Medicine. Total dietary exposures of fluoride can exceed this threshold
amount (0.7mg/day) in infants fed formula reconstituted with optimally fluoridated water.
Review of Potential Adverse Health Effects
Our review,of the literature, consistent with community input, indicates that there are four major potential
health concerns associated with long-term exposure to fluoride: cancer, bone fractures, skeletal fluorosis
and dental enamel fluorosis, and several other conditions for which a much more limited literature
database is available. In this section, we present a summary of the evidence on the likelihood of specific
health risks from drinking water fluoridation. We also include more comprehensive documentation of the
literature reviewed in Appendix 2 to this report.
As described in more detail in the introduction, the FTSG reviewed the toxicological and epidemiological
studies for each of these outcomes as independent lines of evidence. The group considered the weight of
evidence findings as stronger when the toxicological and epidemiological studies were in agreement. The
weight of evidence conclusions are more uncertain when these two independent lines of evidence disagree
with regard to the likelihood of health risks from water fluoridation.
Cancer
Animal Toxicological Studies
There have been two major, recent animal studies that explored the possibility that long-term exposure to
fluoride causes cancer. These studies have been examined by a number of federal agencies and their
interpretations and conclusions of these data are provided below. The first animal toxicology study,
conducted by the National Toxicology Program (NTP), administered fluoride at concentrations of up to 175
mg/L of drinking water [approximately 79 times the concentration in Fort Collins water]. "Although the
results were negative for male and female mice and female rats, there was some evidence of a dose-related
increase in the incidence of osteosarcomas in male rats" (National Research Council [NRC], 1993, p. 10).
The Agency for Toxic Substances and Disease Registry of the U.S. Public Health Service (ATSDR)
summarized the NTP study as follows:
"Based on the finding of a rare tumor in a tissue known to accumulate fluoride, but not at the
usual site for chemically-associated osteosarcomas, a weakly significant dose-related trend, and
the lack of supporting data in female rats and mice of either gender, the NTP concluded that there
was `equivocal evidence of carcinogenic activity of sodium fluoride in male F344/N rats.' NTP
defined equivocal evidence of carcinogenic activity to be a situation where the results show `a
marginal increase in neoplasms that may be chemically related.' NTP further concluded that there
30 Report of the Fort Collins Fluoride Technical Study Group - April 2003
was no evidence that fluoride was carcinogenic at doses up to 4.73 mg/kg/day' in female N344/N
rats, or at doses up to 17.8 and 19.9 mg/kg/day in male and female B6C3Fj mice, respectively"
(Agency for Toxic Substances and Disease Registry [ATSDR], 2001, p. 100).
A second study, sponsored by Proctor and Gamble examined carcinogenic potential of sodium fluoride
administered in feed to Sprague-Dawley rats and CD-1 mice. The data from the Proctor and Gamble
Study were reviewed by the Carcinogenicity Assessment Committee, Center for Drug Evaluation and
Research, Food and Drug Administration (CAC/CDER/FDA) who reported that statistical analysis of the
incidence of bone tumors found no dose-response relationship and that:
"The CAC review concluded that there were flaws and uncertainties in the studies that keep them
from providing strongly reassuring data. However, the committee concluded that the study results
reaffirm the negative finding of the NTP study in female rats, and do not reinforce equivocal
findings in male rats" (as cited by ATSDR, 2001, p. 101).
However, these results were not confirmed by:
"a ...study conducted by Procter & Gamble, in which fluoride was administered in the
diet at doses higher than those in the NTP study. The Procter & Gamble study did
produce a significant dose-related increase in the incidence of osteomas (benign bone
tumors) in male and female mice. However, these lesions were not considered to be
neoplastic and, in any event, have no known counterpart in human pathology" (NRC,
1993, p. 10-11).
Subsequently, the data from both of these toxicology studies were reviewed by the National Research
Council and a U.S. Public Health Service committee. The National Research Council subcommittee
concluded, "the available laboratory data are insufficient to demonstrate carcinogenic effects of fluoride
in animals" (NRC, 1993, p. 11).
Similarly, the U.S. Public Health Service committee concluded:
"When the NTP and the Proctor and Gamble studies are combined, there is a total of eight
individual sex/species groups examined. Seven of these groups showed no significant evidence of
malignant tumor formation. One of these groups; male rats from the NTP study, showed
"equivocal" evidence of carcinogenicity, which is defined by NTP as a marginal increase in
neoplasms - i.e. osteosarcomas - that may be chemically related. Taken together, the two animal
studies available at this time fail to establish an association between fluoride and cancer" (USPHS,
1991, p. 76).
Human Epidemiological Studies
The potential for an association between human cancer and exposure to fluoridated water has also been
explored in many epidemiologic studies and summarized in reviews conducted by the Agency for Toxic
Substances and Disease Registry, U.S. Public Health Service, the World Health Organization, the
National Research Council, National Academy of Science, the U.S. Public Health Service, and the
Medical Research Council of Great Britain. Relevant citations from the texts of these reviews follow; a fuller
description of each is found in Appendix 2.
As typically practiced in animal toxicology studies these doses are about 100-400 times the average dose in
humans in fluoridated communities. The 4.73 mg/kg/day dose is approximately equivalent to an average adult in
Fort Collins drinking about 100 gallons of water per day for a lifetime.
Finding #2: The Risk of Drinking Water Fluoridation 31
The Agency for Toxic Substances and Disease Registry, U.S. Public Health Service (ATSDR)
summarized the epidemiological studies of human cancer as follows:
"Numerous epidemiological studies have examined the issue of a connection between fluoridated
water and cancer. The weight of evidence indicates that no such connection exists. However, all of
the investigations were ecologic studies, and the sensitivity limit of even the most sensitive analysis
in these studies appears to be a 10-20% increase in risk" (ATSDR, 2001, p. 96).
A large epidemiological study conducted by the National Cancer Institute was summarized by ATSDR as
follows:
"An epidemiological study (Hoover et al. 1991) examined >2,300,000 cancer deaths and 125,000
cancer cases in U.S. counties exposed to artificially fluoridated drinking water for up to 35 years.
Taking into account the results of the NTP study... detailed analyses were conducted of cancers
of the joints and bones (especially osteosarcomas), and cancers of the oral cavity and pharynx.
The statistical evaluation was based on analysis of time trends in the observed/expected (O/E)
ratios relative to duration of fluoridation. While elevated O/Es were observed for osteosarcomas
in males, the O/E ratio was inversely related to duration of fluoridation. Thorough analyses of
incidences of oral cancers and cancers at a variety of other sites were conducted by means of very
sensitive statistical tests that were designed to detect changes as small as 10-20%. No consistent
correlation between cancer incidence or mortality and duration of fluoridation was found. An
addendum to the report noted that the age-adjusted national incidence of osteosarcomas increased
by 18% in males for the years 1973-80 and 1981-87; most of the increase was due to a 53%
increase in males under 20 years of age, and there was a larger increase in fluoridated than
nonfluoridated areas. A similar time-trend analysis to that done in the main report found no
correlation between the cancer incidence O/E ratio and duration of fluoridation. Additional
analyses also failed to find a relationship between osteosarcoma incidence in males and exposure
to water fluoridation" (ATSDR, 2001, p. 98).
The National Research Council (National Academy of Sciences) examined the epidemiologic studies of
cancer and exposure to fluoridated drinking water and came to the following conclusion:
"More than 50 epidemiological studies have examined the relation between fluoride
concentrations in drinking water and human cancer. Most studies compared geographic or
temporal patterns of cancer occurrences with distributions of fluoride in drinking water. These
studies provide no credible evidence for an association between fluoride in drinking water and the
risk of cancer" (NRC, 1993, p. 10).
The National Research Council Committee concluded that "the weight of the evidence from the
epidemiological studies completed to date does not support the hypothesis of an association between
fluoride exposure and increased cancer risk in humans" (NRC, 1993, p. 11).
A committee appointed by the U.S. Public Health Service to review the risks and benefits of fluoride
summarized their findings regarding potential cancer risk as follows:
"The ad hoc subcommittee of the Committee to Coordinate Environmental Health and Related
Programs reviewed the results from numerous epidemiologic studies of the relation between
exposure to fluoridated water and cancer that have been conducted during the last 40 years. In
addition to the review of these studies, the Subcommittee reviewed the findings of a recent study
from the National Cancer Institute (NCI), which updated and expanded an earlier county-specific
analysis for cancer mortality in the United States in relation to water fluoridation.... Both this
report and reports from previous international expert panels which have reviewed earlier data
concluded that there is no credible evidence of any association between the risk of cancer and
32 Report of the Fort Collins Fluoride Technical Study Group - April 2003
exposure to either natural or adjusted fluoride in drinking water" (USPHS, 1991, Executive
Summary, p. 4).
Several international bodies have also examined the potential for cancer risk from consumption of
fluoridated water. The N1IS Center at the University of York in Great Britain review (2000) included 26
studies of the association of water fluoridation and cancer, 21 of these studies were from the lowest level
of evidence, level C, with the highest risk of bias, and five from level B. Among the 10 studies that
examined the relationship between fluoride exposure and all-cause cancer incidence and mortality, only
two studies found a statistically significant association: one found a mixed effect with more cancer in two
of eight subgroups, while the other found a significant protective effect (fewer cancers) in persons
exposed to drinking water fluoride. The possible relationship between fluoride exposure and cancers of
bone is of particular interest because fluoride accumulates in bone. Contained in the four studies meeting
the inclusion criteria established by the NHS in which the association between water fluoride exposure
and bone related cancer was examined, there were eight analyses. Four analyses found the direction of
association to be positive (fewer bone cancers in those exposed to fluoride) and three found the direction
to be negative (more cancers in those exposed to fluoride). Similarly, among the 12 analyses of the
association between water fluoride exposure and osteosarcoma (a rare tumor derived from bone
producing cells called osteoblasts), seven found fewer tumor cases; three found more tumor cases and two
found no association. Only one study found a statistically significant association between fluoridation and
either bone related cancer or osteosarcoma. This study found an increased prevalence of osteosarcoma in
males but not females. This study however, also had the lowest validity score (NHS Centre for Reviews
and Dissemination, University of York [NHS], 2000, pp. 54-57). The NHS reviewers concluded:
"There is no clear association between water fluoridation and overall cancer incidence and
morality. This was also true for osteosarcoma and bone/joint cancers. Only two studies
considered thyroid cancer and neither found a statistically significant association with water
fluoridation. Overall, no clear association between water fluoridation and incidence or
mortality of bone cancers, thyroid cancer or all cancers was found" (NHS, 2000, p. xiii).
In the most recent of these reviews, the Medical Research Council of Great Britain examined an earlier
analysis by the University of York (the NHS review discussed above) as well as earlier studies and
reviews. The Medical Research Council concluded:
"The evidence available does not suggest that fluoridation of water increases the risk for cancer in
general or for any particular type of cancer, including osteosarcoma. Neither the York Review nor
other reviews have calculated a pooled estimate of effect; therefore it is difficult to estimate the
maximum increase in risk, which is compatible with the available data. For osteosarcoma, the three
small case-control studies cannot exclude an increase in risk of the order of twofold for exposure to
fluoridated water, but an increase as large as this is not compatible with the ecological data, in
particular those analyzed by Hoover et al. (1991). In conclusion, although a small increase in cancer
risk cannot be excluded, the data do not suggest any increase in risk and in view of the type of data
available it does not seem appropriate to estimate the number of cases of cancer that might be caused
by fluoridation" (MRC, 2002, p. 30).
Fluoride Carcinocienicity Uncertainties
The previously discussed animal toxicological studies were equivocal. To address the uncertainty that
these studies raise, the National Research Council recommended:
"...conducting one or more carefully designed analytical epidemiological (case-control or cohort)
studies to more fully evaluate the relation between fluoride exposure and cancer, especially
osteosarcomas, at various sites, including bones and joints. In conducting such studies, it is
Finding #2: The Risk of Drinking Water Fluoridation 33
important that individual exposure to fluoride from all sources be determined as accurately as
possible" (NRC, 1993, p. 11).
The NHS, University of York review of human epidemiological studies regarding water fluoridation and
osteosarcoma showed that the studies had weak designs and showed mixed results. The National
Research Council concluded that current evidence is not sufficient to rule out a small risk of increased
cancer:
"The existence of such an extensive epidemiological database on fluoride with no consistent
evidence of carcinogenic effects suggests that, if there is any increase in cancer risk due to exposure
to fluoride, it is likely to be small. However, most of these studies used geographic and temporal
comparisons of cancer rates and hence are of limited sensitivity. Further analytical studies with
accurate information on individual fluoride exposures and disease diagnoses are therefore desirable"
(NRC, 1993, p. 10).
The Medical Research Council of Great Britain noted:
"The majority of information, therefore, relates to' whether exposure to artificially fluoridated
water for up to about 30 years may alter cancer rates, with some data for up to 35 years.... In
view of this, there is a need to continue to monitor cancer rates in artificially fluoridated
populations for at least 70 years after fluoridation was introduced. However, it should also be
noted that studies of populations using water with naturally high fluoride levels, to which the
people would have been exposed throughout their life, have not given any indication of an
increase in cancer risk" (MRC, 2002 pp. 30-31).
FINDINGS: Cancer
Although a small increase in cancer risk cannot be excluded, there is no consistent evidence from human
or animal studies that exposure to optimally fluoridated drinking water and other sources of fluoride
causes any form of cancer in humans, including bone and joint cancer. The agreement between the
epidemiological and toxicological literature reduces the uncertainty associated with any one line of
evidence finding. Additional research is needed to address the remaining uncertainty whether community
water fluoridation may cause cancer in humans following long-term exposures of greater than 40 years.
Bone Fractures and Osteoporosis
Two types of studies have been used to examine the possible association between bone fracture and
exposure to fluoride. In the first type, clinical trials have been designed to evaluate the efficacy of fluoride in
reducing fracture risk in persons with osteoporosis, a condition common in post-menopausal women in
which decreased bone density can lead to fractures, especially of the spine, hip and wrist. Because fluoride
increases bone density, it has been hypothesized that it might be effective as a treatment for osteoporosis.
Fluoride doses in earlier studies (30-80 mg F-ion/day) were typically an order of magnitude higher than the
usual exposure from drinking optimally fluoridated water. Lower levels of fluoride (9-23 mg F-ion/day that
are about 4 to 10 times the average dose from dietary sources in a fluoridated community) and sustained
release preparations have been used more recently. A systematic review and meta-analysis of these clinical
trials was published in 2000 by researchers at the University of Ottawa (Haguenauer, Welch, Shea, Tugwell,
& Wells, 2001). As summarized by the Agency for Toxic Substance and Disease Research:
"Haguenauer et al. (2000) performed a meta-analysis to examine the effects of fluoride on the
treatment and prevention of post-menopausal osteoporosis using the data from the Riggs et al.
(1990, 1994), Kleerekoper et al. (1991) and 10 other studies. The meta-analysis showed a
significant increase in bone mineral density in the lumbar spine and hip and a decrease in bone
34 Report of the Fort Collins Fluoride Technical Study Group - April 2003
mineral density in the forearm after 2. or 4 years of fluoride treatment. When the data from all
studies was used, fluoride treatment for 2 or 4 years did not affect the relative risk of vertebral
fractures. However, studies in which the subjects were exposed to low levels of fluoride or a
slow-release formulation for 4 years, a significant decrease in vertebral fracture relative risk was
seen. An increase in the relative risk of nonvertebral fractures was observed when data from all
studies were used; no effect was seen in studies using low levels of fluoride (<30mg/day) or
slow-release fluoride" (ATSDR, 2001, p.87).
The second type of study compares fracture rates among persons or populations exposed to fluoridated
and to nonfluoridated water supplies. A summary of the evidence from five "Tier One" sources (Agency
for Toxic Substances and Disease Registry, NHS University of York, National Research Council, U.S.
Public Health Service and the World Health Organization) follows.
The Agency for Toxic Substances and Disease Registry, stated:
"Numerous studies have examined the possible relationship between exposure to fluoride in
drinking water and the risk of bone fractures. Many of these studies are ecological studies that
examined communities with high level of fluoride in the water or fluoridated water" (ATSDR,
2001, p. 83).
Several prospective and retrospective studies also examined the possible association:
"These studies have found conflicting results, with studies finding a higher or lower incidence of
hip fractures or no differences in hip fracture between humans exposed to fluoride in drinking
water. Several studies have found decreases in hip fracture incidences in communities with fluoride
in the drinking water, suggesting that there may be a beneficial effect" (ATSDR, 2001, p. 83).
The NIIS Centre for Reviews at the University of York included 29 epidemiologic studies in a systematic
review. Most of these studies were not statistically significant in either direction. "The statistically
significant studies were evenly distributed, five indicating an increased risk of fracture and four indicating
a decreased risk" (NHS, 2000, p. 53).
The National Research Council reviewed the evidence regarding fluoride exposure and risk of bone
fracture:
"Of the six epidemiological studies that used geographic comparisons (where no actual intake
data were available), four found a weak association between fluoride in drinking water and a
small increase in the risk of hip (or other bone) fracture ...and the other showed no difference in
fracture risk in women who drank fluoridated or nonfluoridated water" (NRC, 1993, p. 60).
They concluded:
"In view of the conflicting results and limitations of the current data base of fluoride and the risk
of hip fractures and other fractures, there is no basis at this time to recommend that EPA lower
the current maximum contaminant level (MCL) of fluoride of 4 mg/L" (NRC, 1993, p. 61).
The U.S. Public Health Service reviewed the evidence that fluoride in drinking water was associated with
either an increase or a decrease in bone fractures. They concluded:
"Although some epidemiologic studies have suggested that the incidence of certain types of bone
fractures may be higher in some communities with either naturally high or adjusted fluoride
levels, other studies have not detected increased incidence of bone fractures. However, a variety
of potentially confounding factors must be examined to assess whether there is an association
between exposure to fluoride and bone fractures" (USPHS, 1991, Executive Summary, p. 5
Finding #2: The Risk of Drinking Water Fluoridation 35
The World Health Organization (1994) reached a similar conclusion:
"Several recent epidemiological studies of long-term exposure to fluoride in drinking-water at
optimal levels for caries prevention have reached conclusions implicating fluoride as the
causative factor in the increasing incidence of hip fractures in the elderly, owing to increased
brittleness of the cortical bone plates. However, independent reviews of these contemporary
studies conclude that they fail to establish an adequate basis for concluding that fluoride levels in
drinking water are related to hip fractures and bone health (Gordon et al. 1992). Most of the
studies have important limitations that restrict generalization of their results either to the
population as a whole or to determining risks for individuals. Therefore no basis exists for altering
current public health policy on the use of fluorides for caries prevention" (World Health
Organization [WHO], 1994, p. 11).
Bone Effects Uncertainties
The uncertainty regarding the risk of bone fracture from community water fluoridation is evidenced by
the summary of 29 studies reviewed by the NHS at the University of York that found 14 studies (five
statistically significant) with decreased hip fractures among those living in fluoridated communities, 13
studies (four statistically significant) with increased rates of hip fractures, and three additional studies
finding no association. Results of studies of other bone fractures sites were also mixed. The reviewers
rated all but one of the included bone studies as having "low" validity and one as yielding "moderate"
validity (NHS, 2000, p. 48). Studies of this type that compare the incidence of bone fracture across
communities are subject to confounding from a number of sources as described above, including calcium
levels in the water, total calcium and vitamin D intake, use of exogenous estrogens among women and
individual fluoride intake.
The Medical Research Council of Great Britain identified an additional uncertainty:
"A broader consideration of the epidemiological evidence on fluoride and bone health suggests
that it is of higher quality than the York Review indicates. At this stage, perhaps the most
important gap in knowledge concerns the bioavailability of fluoride from different dietary
sources, and in particular the influence, if any, of calcium on uptake of fluoride from drinking
water... If fluoride were shown to be much less completely absorbed from hard than soft water,
the absence of an increased risk of fracture in some published studies would be less reassuring"
(MRC, 2002, p. 28).
The National Research Council called for more studies of fractures that use information from individuals
rather than populations.
"In these studies, it is important that individual information be collected about fluoride intake
from drinking water and from all other sources, reproductive history, past and current hormonal
status, intake of dietary and supplemental calcium and other cations, bone density and other
factors that might influence risk of fracture" (NRC, 1993, p. 61).
Regarding research recommendations on bone effects other than fractures, the Medical Research Council
of Great Britain concluded:
"There are also gaps in the evidence base on bone disorders other than fractures, only a few
epidemiological studies having attempted to assess risks for any of these diseases directly.
However, the gaps could only be regarded as important if there were good reasons to suspect an
effect of fluoridation from out knowledge of biochemistry and toxicology" (MRC, 2002, p. 28).
36 Report of the Fort Collins Fluoride Technical Study Group - April 2003
FINDINGS: Bone Effects
The FTSG agrees with the conclusion of The Medical Research Council of Great Britain that states, "The
possibility of an effect on the risk of hip fracture is the most important in public health terms. The
available evidence on this suggests no effect, but cannot rule out the possibility of a small percentage
change (either an increase or a decrease) in hip fractures" (Medical Research Council, 2002, p. 3).
Skeletal Fluorosis
When ingested in large doses for an extended period of time, fluoride results in thickened bones and
exostoses (skeletal fluorosis). According to the Agency for Toxic Substances and Disease Registry:
"Signs of skeletal fluorosis range from increased bone density to severe deformity, known as
crippling skeletal fluorosis.... Reported cases are found almost exclusively in developing
countries, particularly India, and are associated with malnutrition (Pandit et al. 1940). Tea
consumption and high water intake due to tropical climate are probably also contributing
factors.... It is generally stated that a dose of 20-80 mg/day (equivalent to 10 to 40 ppm in the
water) is necessary for the development of crippling skeletal fluorosis (NAS 1971a), but
individual variation, variation in nutritional status, and the difficulty of determining water
fluoride levels in such situations make it difficult to determine the critical dose.
A study of 116 people who had lived in an area with an average of 8 ppm fluoride in the
drinking water for at least 15 years found a 10-15% incidence of fluoride-related bone changes
(Leone et al. 1995). Coarsened trabeculation and thickened bone were observed, but no exotoses
were evident, and the subjects were asymptomatic" (ATSDR, 2001, p. 82).
Approximately 50% of ingested fluoride is excreted by the kidneys within 24 hours, a small amount is
stored in the teeth, and the rest is mainly deposited in the skeleton (The Lord Mayor's Taskforce on
Fluoridation, 1997, p. 51). Over time, excessive levels of fluoride can produce abnormalities in bone, if
dose and duration are great enough. As shown in Table 6, these abnormalities become detectable on x-
rays, and rarely can result in a clinical syndrome of skeletal fluorosis). Table 6 shows the pre-clinical
(asymptomatic) and clinical stages of skeletal fluorosis along with the most common symptoms. The
amount of fluoride accumulation in the bone tissue of subjects in each stage is also given. One study
found a linear relationship between the concentration of fluoride in bone at autopsy in adult humans and
the concentration of fluoride in their drinking water (ranging from 0.1 to 4 ppm). "Average fluoride levels
in the iliac crest bone ash in people with drinking water fluoride levels of <0.3, 1 and 4 ppm were 700,
2,300, and 6,900 ppm, respectively" (ATSDR, 2001, p. 123, citing Zipkin et al. 1958).
Finding #2: The Risk of Drinking Water Fluoridation 37
Table 6
Preclinical and Clinical Stages of Human Skeletal Fluorosis and Correlation to
Bone Ash Fluoride Concentration
(adapted from Table 23, USPHS 1991, p. 46)
Osteosclerotic Phase Ash Concentration'
(mg F/Kg)
Normal Bone 500-1,000
Preclinical Phase 3,500-5,000
Asymptomatic; slight radiographically-detectable increase in bone mass
Clinical Phase I 6,000-7,000
Sporadic pain; stiffness of joints; osteosclerosis of pelvis & vertebral
column
Clinical Phase II 7,500-9,000
Chronic joint pain; arthritic symptoms; slight calcification of ligaments;
increased osteosclerosis/caneellous bones; with/without osteoporosis of
long bones
Phase III: Crippling Fluorosis >8,400
Limitation of joint movement; calcification of ligaments/neck, vertebral
column; crippling deformities. spine & major joints; muscle wasting;
neurological defects/compression of spinal cord
Ash concentration is the amount of fluoride per weight of bone ash, usually measured from a
sample of bone from the iliac crest
The concentration of fluoride also increases with age. A study cited by Agency for Toxic Substances and
Disease Registry (2001) examined fluoride bone ash concentrations in five people between 64 and 85 who
had lived in an area with water containing Img/L fluoride for at least 10 years. Their average bone fluoride
concentration was 2,250 mg F/Kg (ATSDR, 2001, p. 82). Note that the level of fluoride per weight of bone
ash in long-term residents of fluoridated communities is above the level in "normal bone" but below the
level at which changes can be identified on x-rays, and well below the levels at which symptoms of
skeletal fluorosis begin to appear.
According to a U.S. Public Health Service Committee, "The total quantity of fluoride ingested is the
single most important factor in determining the clinical course of skeletal fluorosis (Krishnamachari,
1986); the severity of symptoms correlates directly with the level and duration of exposure (Fischer, et al.,
1989)" (USPHS, 1991, p. 45).-However there appear to be other important cofactors that render
individuals susceptible to this disease since, "crippling skeletal fluorosis continues to be extremely rare in
the United States... even though for many generations there have been communities with drinking water
fluoride concentrations in excess of those that resulted in this condition in other countries (Singh and
Jolly, 1970)" (IOM, 2000, p. 308).
The National Research Council made the following observations concerning skeletal fluorosis in their
review:
"Crippling skeletal fluorosis might occur in people who have ingested 10-20 mg of fluoride per
day for 10-20 years. During the last 30 years, only five cases have been reported in the United
States. The history of fluoride intake for two of the cases was determined with reasonable
accuracy (Sauerbrunn et al., 1965; Goldman et al., 1971). The individuals consumed up to 6 L of
water per day containing fluoride at 2.4-3.5 mg/L in one case and 4.0-7.8 mg/L in the other. The
38 Report of the Fort Collins Fluoride Technical Study Group - April 2003
daily fluoride intake was estimated at 15-20 mg for 20 years. In general, this intake would be
associated with a drinking-water supply containing fluoride at about 10 mg/LZ.
Thus, crippling skeletal fluorosis in the United States has been rare and not a public
health problem (Leone et al., 1954; Stevenson and Watson, 1957), even though for many
generations there have been communities with drinking water fluoride concentrations in excess of
those that have resulted in the condition in other countries (Singh and Jolly, 1970). The puzzling
geographic distribution of the disorder usually is ascribed to unidentified dietary factors that
render the skeleton more or less susceptible.
The small member of cases of skeletal fluorosis in the United States has ruled out the
possibility of systematic epidemiological evaluation. Based on limited data in the literature on
skeletal fluorosis, the subcommittee [National Research Council] concludes that skeletal fluorosis
is not a public health issue in the United States" (NRC, pp. 59-60).
The Locker review conducted for the Ontario Ministry of Health (1999) reported:
"Most estimates indicate that crippling fluorosis is associated with chronic fluoride exposures of
> 10 mg/day for at least ten years. These exposures occur as either endemic (exposure to the
naturally fluoridated drinking water) or industrial (e.g. exposure to the cryoiite dust) (Fejerskov,
1996; Whitford, 1996). Beside the dose and duration of fluoride exposure, the development of
skeletal fluorosis is influenced by various other factors. The most common are age, physical
activity, kinetics of bone remodeling, nutritional status and renal insufficiency. Epidemiological
studies of bone mineral density have not detected changes consistent with skeletal fluorosis
resulting from the consumption of drinking water containing fluoride at the concentrations
considered optimal for caries prevention" (Locker, 1999, p. 44).
Skeletal Fluorosis Uncertainties
According to the Agency for Toxic Substances and Disease Registry, "The incidence of skeletal fluorosis
in the United States is unknown, since it appears that the early signs can only be identified radiologically"
(ATSDR, 2001, p. 82).
Three members (GM, EC, RN) of the FTSG were concerned that the studies on skeletal fluorosis
estimated the likelihood of occurrence based on a dosage of 10-20 mg of fluoride per day over at least 10-
20 years, but there was limited data regarding the likelihood of occurrence based on a cumulative dose
over a lifetime of exposure. This was particularly concerning to them given the fact that fluoride
accumulates in the bone. Skeletal fluorosis is rarely reported in the United States. Because the symptoms
of clinical non-crippling stages of skeletal fluorosis (pain in the bones and joints, muscle weakness,
fatigue, calcification of ligaments and bone spurs) two FTSG members (GM, EC) wondered if these
symptoms could be misdiagnosed, resulting in under-reporting among susceptible individuals living in
communities with optimally fluoridated drinking water (e.g. persons with long-term nutritional
deficiencies such as deficiencies of protein, calcium, magnesium, and/or vitamin C and people with
chronic kidney failure).
z Approximately 10 times the concentration in Fort Collins water.
Finding #2: The Risk of Drinking Water Fluoridation 39
FINDINGS: Skeletal Fluorosis
At the concentrations of fluoride provided in Fort Collins water including exposures from all sources over
a lifetime, skeletal fluorosis caused by drinking water exposure is not likely to be a health issue. The
available data are not consistent with a likelihood of increased human skeletal fluorosis from city water
fluoridation.
Additional research is needed to reduce the remaining uncertainty if cumulative exposure to all sources of
fluoride (including drinking water fluoride at levels of I mg/L) over a lifetime may lead to pre-clinical or
milder forms of skeletal fluorosis in some sensitive populations.
Dental Enamel Fluorosis
A summary of the issue concerning enamel fluorosis and water fluoridation is found in the report from the
Centers for Disease Control and Prevention, Recommendations for using, fluoride to prevent and control
dental caries in the United States (2001):
"Fluoride ingested during tooth development can also result in a range of visually detectable
changes in enamel opacity (i.e., light refraction at or below the surface) because of
hypomineralization. These changes have been broadly termed enamel fluorosis, certain extremes
of which are cosmetically objectionable (49). (Many other developmental changes that affect the
appearance of enamel are not related to fluoride (50).) Severe forms of this condition can occur
only when young children ingest excess fluoride, from any source, during critical periods of tooth
development. The occurrence of enamel fluorosis is reported to be most strongly associated with
cumulative fluoride intake during enamel development, but the severity of the condition depends
on the dose, duration, and timing of fluoride intake. The transition and early maturation stages of
enamel development appear to be most susceptible to the effects of fluoride (51); these stages
occur at varying times for different tooth types. For central incisors of the upper jaw, for example,
the most sensitive period is estimated at age 15-24 months for boys and age 21-30 months for
girls (51,52).
Concerns regarding the risk for enamel fluorosis are limited to children aged <8 years;
enamel is no longer susceptible once its pre-eruptive maturation is complete (11). Fluoride
sources for children aged <8 years are drinking water, processed beverages and food, toothpaste,
dietary supplements that include fluoride (tablets and drops), and other dental products.
The very mild and mild forms of enamel fluorosis appear as chalklike, lacy markings
across a tooth's enamel surface that are not readily apparent to the affected person or casual
observer (53). In the moderate form, >50% of the enamel surface is opaque white. The rare, severe
form manifests as pitted and brittle enamel. After eruption, teeth with moderate or severe fluorosis
might develop areas of brown stain (54). In the severe form, the compromised enamel might break
away, resulting in excessive wear of the teeth. Even in its severe form, enamel fluorosis is
considered a cosmetic effect, not an adverse functional event. (8, 11, 55, 56)
When enamel fluorosis was first systemically investigated during the 1930s and 1940s, its
prevalence was 12%-15% for very mild and mild forms and zero for moderate and severe forms
among children who lived in communities with drinking water that naturally contained 0.9-1.2 ppm
fluoride (53). Although the prevalence of this condition in the United States has since increased (8, 58,
59), most fluorosis today is of the mildest form, which affects neither cosmetic appearance nor dental
function. The increased prevalence in areas both with and without fluoridated community drinking
water indicates that, during the first 8 years of life (8), the total intake of fluoride from all sources has
increased for some children (Centers for Disease Control and Prevention [CDC], 2001, pp. 6-7).
(8, 11, 49, 50, 51, 52, 53, 54, 55, 56,58, 59) References within a quote are available in the source document.
40 Report of the Fort Collins Fluoride Technical Study Group - April 2003
The Medical Research Council of Great Britain adds the following terminology, "Dental fluorosis is a
form of developmental defect of tooth enamel. Histologically it presents as hypocalcification, while
clinically it ranges from barely visible white striations on the teeth through to gross defects and staining
of the enamel" (MRC, 2002, p.19).
Prevalence of Enamel Fluorosis in the U.S.
The U.S. Centers for Disease Control and Prevention reviewed the most recent national estimates of the
prevalence of fluorosis:
"The 1986-1987 National Survey of Dental Caries in U.S. School Children (the most recent
national estimates of enamel fluorosis prevalence) indicated that the prevalence of any enamel
fluorosis among children was 22%-23% (range 26% of children aged 9 years to 19% of those aged
17 years (60, 61). Almost all cases reported in the survey were of the very mild or mild form, but
some cases of the moderate (1.1%) and severe (0.3%) forms were observed" (CDC, 2001, pp. 8-9).
The estimates cited above were averages across all communities, ranging from very low to very high
levels of fluoride. "In communities with drinking water containing 0.7-1.2 ppm fluoride, the prevalence
was 1.3% for the moderate form of enamel fluorosis and zero for the severe form; thus, few cases of
enamel fluorosis were likely to be of cosmetic consequence (8,61)" (CDC, 2001, p. 12).
According to a recent study, the mean prevalence of dental fluorosis, relative to Dean's original data, has
increased by 39% in optimally fluoridated areas and by 91% in nonfluoridated areas (Pendrys & Stamm,
1990, cited in Lewis & Bunting, p. 156).
R.UORTDR
a-
-3
7-
6-
f5
-2
4-
z
3-
2-
0.6 U L'
1-i
0 0
0 7 2 3
Fluoride Concentration In Water (ppm)
Figure 1. Taken from Figure 8-1, page 299, of the Committee on the Scientific Evaluation of
Dietary Reference Intakes, Food & Nutrition Board, Institute of Medicine (2000)
Relationships among caries experience (solid line), dental fluorosis index (dashed line), and the fluoride
concentration of drinking water. A fluorosis index value of 0.6 was judged to represent the threshold for a
problem of public health significance. The data are based on the examination of 7,257 12-to 14-year old
children (Dean, 1942).
(8, 60, 61) References within a quote are available in the source document.
Finding #2: The Risk of Drinking Water Fluoridation 41
As demonstrated in the total exposures section earlier in this finding, total exposures have increased and
at optimal levels of water fluoridation are higher than shown in Figure 1 above.
The NHS Review at the University of York found that at a fluoride level of 1 ppm an estimated 12,5% of
exposed people would have fluorosis that they would find aesthetically concerning" (NHS, 2000, p. xiii).
The NHS Review looked at 88 studies of dental fluorosis:
"All of the studies were of evidence level C (lowest quality), except one level B. From these
models, the pooled estimate of the prevalence of fluorosis at a water fluoride concentration of 1.0
ppm was 48%...and for fluorosis of aesthetic concern 12.5%" (NHS, 2000, p. 45).
Contribution of CWF to Enamel Fluorosis
Only a fraction of current levels of fluorosis in a fluoridated community like Fort Collins can be attributed
to drinking optimally fluoridated water. In the context of multiple sources of ingested fluoride, how much
does water fluoridation at optimal levels contribute to the overall prevalence of fluorosis? There are two
lines of reasoning that have been used to answer this question. The first is to use levels of fluorosis in
studies conducted in communities before fluoride was present in the diet, bottled waters, and dental
products as an estimate of what water fluoride contributes. The National Research Council follows this
line of reasoning with the following:
"In general, the evidence supports the conclusion that fluoridation at the recommended
concentrations, in the absence of fluoride from other sources, results in a prevalence of mild-to-very
mild (cosmetic) dental fluorosis in about 10% of the population and almost no cases of moderate or
severe dental fluorosis. At five or more times the recommended concentration, the proportion of
moderate-to-severe dental fluorosis is substantially higher" (NRC, 1993, p. 5).
A second approach is to compare relative levels of fluorosis in communities with and without fluoridated
water. Lewis and Banting (1994) and the NHS Center for Reviews and Dissemination at the University of
York (2000) conducted reviews and synthesis of the literature regarding fluorosis. Both reviews found
that the risk of fluorosis has increased in both optimally fluoridated (1.0 mg/L) and low-fluoride
communities (0.4 mg/L), with the absolute difference in prevalence of fluorosis remaining stable at about
15%. Lewis and Banting estimated that the percent of fluorosis attributable to water fluoridation dropped
from nearly 100% in the 1940s to 40% in the early 1990s. The remaining 60% was attributed to increased
use of fluoride dental products and to the "halo effect" (Lewis & Banting, 1994, p. 156).
Other Contributing Causes of Enamel Fluorosis
A large number of studies have reported an association between fluoride supplement use and enamel
fluorosis (NRC, 1993 p. 43). In response to accumulated evidence the supplement dosage schedule for
children nine and younger was markedly reduced in the U.S. in 1994. Levy and Muchow (1992) and
Pendrys and Morse (1990) are among those who documented that improper dosing of supplements is
common and that inappropriate use of fluoride supplements in children living in fluoridated communities
is an important cause of fluorosis. Swallowing of toothpaste by preschool children and prolonged use of
powdered infant formula in fluoridated communities have been identified as risk factors for fluorosis as
well (NRC, 1993, pp. 311-312; CDC, 2001, pp. 11-12). Several studies have attempted to estimate the
relative impact of specific fluoride sources on the prevalence of enamel fluorosis in the U.S. and Canada
(Pendrys, Katz, & Morse, 1994; Osuji, et al., 1988; Pendrys, 2000). Pendrys (2000) reported findings
from a study of 663 middle school students:
"In the nonfluoridated study sample, sixty-five percent of the enamel fluorosis cases were
attributed to fluoride supplementation under the pre-1994 protocol. An additional 34 percent were
explained by the children having brushed more than once per day during the first two years of
42 Report of the Fort Collins Fluoride Technical Study Group - April 2003
life. In the optimally fluoridated study sample, 68 percent of the enamel fluorosis cases were
explained by the children using more than a pea-sized amount of toothpaste during the first year
of life, 13 percent by having been inappropriately given a fluoride supplement, and 9 percent by
the use of infant formula in the form of a powdered concentrate" (Pendrys, 2000, p. 746).
The Institute of Medicine committee report on dietary reference intakes (1997) concluded that intakes of
fluoride from water and diet have remained about the same since the 1940s, so that, in optimally
fluoridated communities, "...the additional intake by children at risk of enamel fluorosis almost certainly
derives from the use of fluoride-containing dental products" (IOM, 2000, p. 312).
Using the National Research Council's logic in estimating fluorosis rates attributable to community water
fluoridation in the absence of other fluoride sources, the 12-15% prevalence of dental fluorosis that
existed in optimally fluoridated communities before the introduction of other fluoride sources can be
thought to be the amount of current fluorosis due to drinking Fort Collins water. Given that, as many as
160-200 children in Fort Collins may develop enamel fluorosis in their permanent teeth annually that may
be statistically attributable to consumption of community fluoridated water, all of it of the very mild or
mild forma. This estimate theoretically represents the amount and severity, of fluorosis that would be
averted by suspending water fluoridation. Many more children, not so easily determined, may develop
dental fluorosis from incorrectly using fluoridated dental products such as ingesting toothpaste or taking
fluoride supplements on a regular basis, between the ages of four months and eight years. Fluorosis
attributable to these sources would not be expected to decrease if Fort Collins suspended water fluoridation.
Although moderate to severe enamel fluorosis is not caused by community water fluoride at 1 ppm by itself,
some reduction in the incidence of moderate to severe fluorosis from exposure to all sources of fluoride
would be expected if community water fluoridation were eliminated.
Given the availability and indiscriminate use of fluoridated dental products, children in the vulnerable
ages in both fluoridated and nonfluoridated communities may be exposed to excessive amounts of
fluoride. The Canadian city of Calgary came to the following conclusion regarding the problem of enamel
fluorosis among children:
"The Panel recommends that health authorities pay more attention to identifying uncontrolled
sources of fluoride, especially due to children swallowing high fluoride toothpaste. Reducing
uncontrolled sources of fluoride would be a more effective means of reducing dental fluorosis
than eliminating fluoridation of water" (Expert Panel for Water Fluoridation Review, City of
Calgary, 1998, p. 30).
The Center for Disease Control and Prevention recommends that the medical and dental communities and
the media educate the public about the potential for increasing the prevalence and severity of enamel
fluorosis if children consuming fluoridated water are treated with fluoride supplements or consume
excessive amounts of fluoridated toothpaste (CDC, 2001, p. 26).
Dental Fluorosis Uncertainties
Uncertainties identified by the FTSG (or specific members):
• The current prevalence of dental fluorosis in fluoridated and nonfluoridated communities in our
region is unknown.
• The public's perceptions regarding the aesthetic acceptability or lack of acceptability of mild to
moderate dental fluorosis is unknown.
3 The average number of children in each age of life between 4 months and 8 years in Fort Collins is about
1350 according to 2000 U.S. Census data. The prevalence of fluorosis measured in the early community
fluoridation trials was 12%-15% all the very mild to mild forms. Therefore, (1350)*(12% to 15%) = 162 to 203
children per year may develop fluorosis.
Finding #2: The Risk of Drinking Watcr Fluoridation 43
• It is not known whether the prevalence of dental fluorosis would decrease or increase if Fort
Collins were to suspend water fluoridation.
FINDINGS: Dental Fluorosis
At the concentrations of fluoride provided in Fort Collins water, in combination with other sources of
fluoride, as many as one in four children under age eight may develop very mild to mild dental fluorosis.
This degree of fluorosis may or may not be detectable by the layperson. With oral health as the goal, this
degree of dental fluorosis is considered an acceptable adverse effect given the benefits of caries
prevention. Since about 60% of dental fluorosis can be attributed to other sources of fluoride (particularly
toothpaste and other dental products) parental supervision over tooth paste swallowing in their young
children and proper prescribed supplementation in infants will likely reduce development of enamel
fluorosis more than the removal of added fluoride in drinking water.
Thyroid Function
Questions raised at the public meeting about the potential for thyroid impacts from drinking water
fluoridation led the FTSG to inquire about studies of the relationship between fluoride intake and thyroid
function. Some at the public meeting pointed out that fluoride had been used to treat hyperthyroidism and
questioned whether drinking water fluoridation would exacerbate hypothyroidism.
Staff pursued this question and produced 25 abstracts and some information from the "Tier One"
literature for FTSG review and discussion. The literature search included an extensive search of the
National Library of Medicine Database as well as Medlin and all major biomedical databases available
through the Colorado State University Morgan Library and the University of Colorado Health Sciences
Center Dennison Library. See reference list in Appendix A.
Of most relevance and therefore having the greatest impact on the FTSG findings are three publications.
Eichner, Borner, Henschler, Kohler, and Moll (1981) examined 26 women who received 40 mg of sodium
fluoride twice a day (equivalent 36 mg of fluorine) for three to six months as a treatment for osteoporosis.
In a second study published separately by two different lead authors, Hasling, Nielsen, Melsen, and
Mosekilde (1987) and Mosekilde, Charles, Eriksen, Hasling, and Melsen (1986), described 163 patients
treated for eight years (total of 460 patient years) with a combination of sodium fluoride (60 mg/day),
calcium phosphate (45 mmol/day) and vitamin D2 (18,000 IU/day). Both cited studies found no change in
thyroid function.
Thyroid Uncertainties
There were some studies identified in the FTSG's literature search that suggested a deleterious effect on
the thyroid by fluoride. While these studies were considered to be of lower quality or relevance, two
members of the FTSG held that there remains uncertainty regarding the effect of fluoride on thyroid
structure and function. The Medical Research Council commented:
"The York review listed three studies in which goiter was the outcome of interest. Two of these
studies (Gedalia & Brand, 1963; Jooste et al., 1999) found no significant association with water
fluoride level. The third (Lin et al., 1991) found a significant positive association between
combined high fluoride/low iodine levels and goiter. However, because this study looked at
combined fluoride/iodine uptakes, and has not been published in a peer reviewed journal,
the findings should be treated cautiously. Further work on this aspect is of low priority" (MRC,
2002, p. 34).
44 Report of the Fort Collins Fluoride Technical Study Group - April 2003
FINDINGS: Thyroid Effects
In the literature reviewed, doses appropriate for caries reduction were not shown to negatively impact
thyroid function. Studies in which humans received doses significantly higher than the optimum fluoride
intake for long periods of time showed no negative impact on thyroid function. For those with
hypothyroidism, the risks of alteration of thyroid structure or function are very low. The absence of our
finding any conclusive evidence that drinking water fluoride exposures causes increased risk to thyroid
function does not prove that fluoride can not affect thyroid function. The available data are consistent
with a finding of a low likelihood of risk to human thyroid function from water fluoridation.
Immune System Effects
Potential immune system' effects are of two types-hypersensitivity (allergic) reactions and
immunotoxicity effects (weakening of the immune system). Information on both is limited.,
With respect to allergic reactions, the Medical Research Council of Great Britain notes:
"Information regarding the allergic potential of fluoride in drinking water is sparse. A paper by
Spittle (1993) concluded that some individuals exhibit an allergic/hypersensitivity reaction to
fluoride, but reviews by NRC (1993), NHMRC (1991) and Chalacombe (1996) all concluded that
the studies undertaken do not support claims that fluoride is allergenic. They considered the
weight of evidence to show that fluoride is unlikely to produce hypersensitivity or other
immunological effects" (MRC, 2002, p. 32).
The U.S. Public Health Service (1991) and the National Research Council (1993) both concluded the
following:
"The literature pertaining to immunological effects of fluoride is limited. Although direct
exposure to high concentrations of sodium fluoride in vitro affects a variety of enzymatic
activities, the relevance of the effects in vivo is unclear. Standardized immunotoxicity tests of
sodium fluoride at relevant concentrations and routes of administration have not been conducted.
The weight of evidence shows that fluoride is unlikely to produce hypersensitivity and other
immunological effects" (NRC, 1993, p. 9; USPHS, 1991, p. 70).
Immunological Svstem Effects Uncertainties
The Medical Research Council noted the sparse amount of evidence regarding adverse effects to the
human immune system. They concluded that, "There is no information on the immunotoxicity of fluoride.
Further work in this area would be useful, but in the absence of obvious toxic mechanisms for such an
effect is considered to be of low priority" (MRC, 2002, p. 32).
With respect to immunotoxicity effects, one FTSG member submitted a paper entitled Is the Ingestion of
Fluoride an Immunosuppressive Practice? that cites several in vitro observations to suggest that, "the
habitual ingestion of small doses of fluoride, even as small as the 1 mg/L contained in fluoridated water,
may decrease the function of the immune system" (Sutton, 1991).
Finding #2: The Risk of Drinking Water Fluoridation 45
FINDINGS: Immunological Effects
Overall, evidence is lacking that exposure to fluoride through drinking water causes any problems to the
human immune system. The absence of our finding any conclusive evidence that drinking water fluoride
exposures causes increased risk to human immune system function does not prove that fluoride is
harmless to the human immune systems.
Other Potential Health Effects
The potential for associations between a number of other potential adverse health effects and exposure to
fluoridated water has been explored in many epidemiologic and toxicological studies and summarized in
reviews conducted by the Agency for Toxic Substances and Disease Registry, the World Health
Organization, the National Research Council of the National Academy of Science, and the U. S. Public
Health Service. The following areas have been studied:
Effects of fluoride on the renal system
• Effects of fluoride on the gastrointestinal system
• Effects of fluoride on hypersensitivity and the immune system (described above)
• Effects of fluoride on reproduction
• Genotoxicity
• Developmental effects including birth defects and Down Syndrome
• Effect of fluoride on all-cause mortality
As in the above sections, relevant citations from the texts of these reviews follow; a fuller description of
each is found in Appendix 2 to this document.
The National Research Council of the National Academy of Sciences came to the following conclusion
on these issues:
"The subcommittee concludes that available evidence shows that the threshold dose of fluoride in
drinking water for renal toxicity in animals is approximately 50 mg/L. The subcommittee
therefore believes that ingestion of fluoride at currently recommended concentrations is not likely
to produce kidney toxicity in humans..:. The subcommittee concludes that the available data
show that the concentrations of fluoride found in drinking water in the United States are not likely
to produce adverse effects in the gastrointestinal system.... The weight of evidence shows that
fluoride is unlikely to produce hypersensitivity and other immunological effects.... The
subcommittee concludes that the fluoride concentrations associated with adverse reproductive
effects in animals are far higher than those to which human populations are exposed.
Consequently, ingestion of fluoride at current concentrations should have no adverse effects on
human reproduction.... The subcommittee concludes that the genotoxicity of fluoride should not
be of concern at the concentrations found in the plasma of most people in the United States....
Based on its review of available data on toxicity of fluoride, the subcommittee concludes that
EPA's current MCL of 4 mg/L for fluoride in drinking water is appropriate as an interim
standard" (NRC, 1993, pp. 7-11).
The U.S. Public Health Service concluded in 1991:
"Chronic low-level exposure of healthy individuals does not appear to present problems in other
organ systems, such as the gastrointestinal, the genitourinary, and the respiratory systems....
Chronic low level fluoride exposure is not associated with birth defects. Studies also fail to
establish an association between fluoride and Down Syndrome. Genotoxicity studies of fluoride,
which are highly dependent on the methods used, often show contradictory findings. The most
46 Report of the Fort Collins Fluoride Technical Study Group April 2003
common finding is that fluoride has not been shown to be mutagenic in standard tests on bacteria
(Ames Test). In some studies with different methodologies, fluoride has been reported to induce
mutations and chromosome aberration in cultured rodent and human cells. The genotoxicity of
fluoride in humans and animals is unresolved despite numerous studies" (USPHS, 1991, pp.
87 & 89).
Uncertainties Regarding Other Health Effects
Several other adverse effects have been proposed as being associated with elevated with fluoride intake.
They include:
• Effects on the pineal gland
• Senile dementia
• Age at menarche
• Anemia during pregnancy
• Sudden infant death syndrome
• Primary degenerative dementia
• Reduced intelligence and other central nervous system effects
• The possibility that fluoride added to water could influence toxicity from other substances (i.e.,
by causing leaching of aluminum from cookware or affecting the uptake or bioavailability of
toxic substances such as aluminum and lead in the gut)
The Medical Research Council of Great Britain as well as the Agency for Toxic Substances and Disease
Registry found the available infonnation on these effects to be limited and inconclusive. The Medical
Research Council noted, "Further targeted research may be warranted, but this is presently of low priority
unless and until critical literature reviews are undertaken that demonstrate specific research needs" (MRC,
2002, p. 34).
Fluoride and Blood Lead Levels
The concern regarding the possible association between blood lead levels and the use of hydrofluorosilicic acid
(HFS) is considered in Finding #4. Two recent ecological studies found a significant association between
community average blood lead levels in children residing in areas with water fluoridated using HFS, compared
to those residing in communities fluoridated with sodium fluoride, or not fluoridated (Masters & Coplan, 1999;
Masters, Coplan, Hone, & Dykes, 2000). According to the U.S. Environmental Protection Agency, there is no
reliable evidence to suggest that this fluoridation agent may increase blood lead levels. The Medical Research
Council of Great Britain concludes, "This appears to be a controversial area and further studies are awaited"
(MRC, 2002, p. 36). The National Toxicity Program recently nominated the use of 117S as a fluoridation agent
for a formal review.
Sensitive Populations
The Agency for Toxic Substances Disease Registry toxicological profile identified the following
populations as potentially exhibiting a different or enhanced response to fluoride exposure.
"Existing data indicate that subsets of the population may be unusually susceptible to the toxic
effects of fluoride and its compounds. These populations include the elderly, people with
deficiencies of calcium, magnesium, and/or vitamin C, and people with cardiovascular and kidney
problems. However, these effects would not be expected at typical exposure levels (at I ppm
fluoride)" (ATSDR, 2001, p. 143).
Finding #2: The Risk of Drinking Watcr Fluoridation 47
FINDINGS: Other Health Effects
The potential for other health effects was reviewed by the FTSG. There was not adequate evidence to
consider any of these other potential adverse effects a concern with respect to fluoridation of Fort Collins
water supplies. The absence of our finding any conclusive evidence that drinking water fluoride
exposures causes other potential health effects does not prove that fluoride can not cause other potential
health effects.
48 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Reference List
Agency for Toxic Substances and Disease Registry. (2001). DRAFT Toxicological Profile for Fluorine,
Hydrogen Fluoride, and Fluorides. U.S. Public Health Service.
American Academy of Pediatrics. (1995). Committee on Nutrition, Pediatrics, 95, 777.
Centers for Disease Control and Prevention. (2001). Recommendations for using fluoride to prevent and
control dental caries in the United States. Morbidity and Mortality Weekly Report (MMWR),
RR-14.
Committee on the Scientific Evaluation of Dietary Reference Intakes, Food & Nutrition Board, Institute
of Medicine. (2000). Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin
D, and Fluoride. Washington, D.C.: National Academy Press.
Committee to Coordinate Environmental Health and Related Programs, USPHS. (1991). Review of
Fluoride: Benefits and Risks: Report of the subcommittee on fluoride of the EHPC. Public Health
Service, Department of Health and Human Services.
Dabeka, R.W. & McKenzie, A.D. (1995). Survey of lead, cadmium, fluoride, nickel, and cobalt in food
composites and estimation of dietary intakes of these elements by Canadians in 1986-1988.
Journal ofA OA C International, 78(4), 897-909.
Dean, IIT. (1942). The investigation of physiological effects by the epidemiological method. In: Moulton
FR, ed. Fluorine and Dental Health. Washington DC: American Association for the
Advancement of Science, 23-31.
Eichner, R., Borner, W., Henschler, D.; Kohler, W., & Moll, E. (1981). Osteoporosis therapy and thyroid
function. Influence of 6 months of sodium fluoride treatment on thyroid function and bone
density. Fortschr Med., 99(10), 342-348.
Expert Panel for Water Fluoridation Review, City of Calgary. (1998). Report of the expert panel for water
fluoridation review appointed by the standing committee on operations and environment.
Calgary, Canada.
Haguenauer, D., Welch, V., Shea, B., Tugwell, P., & Wells, G. (2001). Fluoride for treating
postmenopausal osteoporosis [review]. The Cochrane Database of Systematic Reviews, Issue 3,
no page numbers..
Hasling, C., Nielsen, H.E., Melsen, F., & Mosekilde, L. (1987). Safety of osteoporosis treatment with
sodium fluoride, calcium phosphate and vitamin D. Mineral Electrolyte Metabolism, 13(2),
96-103.
International Programme on Chemical Safety. (1984). Environmental Health Criteria 36: Fluorine and
Fluorides. Geneva, Switzerland: World Health Organization.
Levy, S.M. & Muchow, G. (1992). Provider compliance with recommended dietary fluoride supplement
protocol. American Journal of Public Health, 82(2), 281-283.
Lewis, D.W. & Banting, D.W. (1994). Water fluoridation: current effectiveness and dental fluorosis.
Community Dentistry and Oral Epidemiology, 22(3), 153-158.
Locker, D. (1999). Benefits and Risks of Water Fluoridation - An update of the 1996 Federal-Provincial
Sub-committee Report. University of Toronto, Canada.
Finding #2: The Risk of Drinking Water Fluoridation 49
The Lord Mayor's Taskforce on Fluoridation. (1997). The Lord Mayor's Taskforce on Fluoridation -
Final Report to Brisbane City Council. Brisbane, Australia.
Masters, R.D. & Coplan, M.J. (1999). Water treatment with silicofluorides and lead toxicity.
International Journal of Environmental Studies, 56, 435-449.
Masters, R.D., Coplan, M.J., Hone, B.T., & Dykes, J.E. (2000). Association of silicofluoride treated water
with elevated blood lead. Neurotoxicology, 21(6), 1091-1100.
Medical Research Council. (2002). Working Group Report. Water Fluoridation and Health. London, UK:
Medical Research Council.
Mosekilde, L., Charles, P., Eriksen, E.F., Hasling, C., & Melsen, F. (1986). Treatment with sodium
fluoride, calcium phosphate and ergocalciferol in spinal osteoporosis. Effect on calcium balance,
calcium metabolism, bone remodelling and side-effects. Ugeskrift for Laerger, 148, 3449-3453.
National Research Council. (1993). Health Effects ofingested Fluoride. Washington, D.C.: National
Academy Press.
National Health Service Centre for Reviews and Dissemination, University of York. (2000). A Systematic
Review of Public Water Fluoridation. York, UK: York Publishing Services Ltd.
Osuji, 0.0., Leake, J.L., Chipman, M.L., Nikiforuk, G., Locker, D., & Levine, N. (1988). Risk factors for
dental fluorosis in a fluoridated community. Journal of Dental Research, 67(12), 1488-1492.
Pendrys, D.G. (2000). Risk of enamel fluorosis in nonfluoridated and optimally fluoridated populations:
considerations for the dental professional. Journal of the American Dental Association, 131(6),
746-755.
Pendrys, D.G., Katz, R.V., & Morse, D.E. (1994). Risk factors for enamel fluorosis in a fluoridated
population. American Journal of Epidemiology, 140(5), 461-471.
Pendrys, D.G. & Morse, D.E. (1990). Use of fluoride supplementation by children living in fluoridated
communities. ASDC Journal Dent Child, 57(5), 343-347.
Sutton, P. R. (1991). Is the ingestion of fluoride an immunosuppressive practice? Medical Hypotheses,
35(l),1-3.
Whitford, G. M. (1994). Intake and metabolism of fluoride. Advances in Dental Research, 8(1), 5-14.
World Health Organization. (1994). Report of a WHO Expert Committee on Oral Health Status and
Fluoride Use. WHO Technical Report Series, No. 846 ed. Geneva, Switzerland: World Health
Organization.
50 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Finding #3 - Costs and Benefits, Inciuding the Distribution of Costs
and Benefits
Cost-Effectiveness of Community Water Fluoridation
Economic analyses conducted before the mid-1980s found that the value of dental decay averted by
community water fluoridation exceeded the cost to fluoridate community water supplies by as much as
8:1 (Davies, 1973; Nelson & Swint, 1976; Niessen & Douglass, 1984; White, Antczak-Bouckoms, &
Weinstein, 1989). However, since the 1970s, a number of factors have given rise to questions about the
possible reduced effectiveness and cost-effectiveness of community water fluoridation (Lewis & Banting,
1994). First, as noted in Finding #1, the widespread use of discretionary fluorides and the increased levels
of fluoride in processed foods and beverages has led to smaller differences in the mean exposure to
topical and systemic fluorides between fluoridated and nonfluoridated communities. Second, there has
been a related decrease in the overall level of caries in the U.S. and many other developed countries,
whether water supplies are fluoridated or not (Committee to Coordinate Environmental Health and
Related Programs, USPHS [USPHS], 1991, p. 31). Finally, there has been an increase in the prevalence
of dental fluorosis in both fluoridated and nonfluoridated communities (see Finding #2). The general
reduction in caries and increase in dental fluorosis raises the question of whether it is stilt clinically and
economically justified to replace existing fluoridation equipment and continue to fluoridate water supplies
in Fort Collins.
Literature Review
The Fluoride Technical Study Group (FTSG) conducted a McXine, Internet, and secondary reference
search for economic analyses of community water fluoridation published since the dramatic drop in caries
prevalence that was documented by national survey data up through the mid-1980s. Criteria for inclusion
of articles for review were:
1. the study included an assessment of community water fluoridation,
2. there was a comparison between cost and consequences, and
3. the study was published in English in a peer-reviewed journal between 1989 and 2002.
We defined an ideal economic analysis by the following criteria: the analysis took a societal perspective;
it was based on a synthesis of U.S. incidence and effectiveness data from the 1980s or later from several
sources; it included costing, which allowed for estimation of resources used; it used a long enough time
horizon to capture all the effects of fluoridation; it specified a discount rate'; and it included multi-way
sensitivity analyseS2 to assess uncertainties.
The FTSG identified two U.S.-based cost-effectiveness analyses of community water fluoridation
published between 1989 and 2001 (Appendix 3, Table 1). Several cost-effectiveness analyses from other
industrialized countries were also identified: two 1990 studies using data from the UK, a 1993
unpublished report from the UK and a report from New Zealand published in 2001 (Appendix 3, Table 2).
The two U.S. studies, the report from NZ and a UK study estimated the cost of community water
fluoridation per averted single surface restoration; two UK studies used tooth-level caries data. Two
additional foreign studies that addressed the effectiveness of community water fluoridation in light of the
general reduction in caries prevalence in Ireland and Scotland are included in Appendix 3, Table 2.
A measure of people's preference for money and health now rather than in the future.
2 "A method to determine the robustness of an assessment by examining the extent to which results are
affected by changes in methods, values of variables, or assumptions" (Last, 1995).
Finding #3: Costs and Benefits, Including the Distribution of Costs and Benefits 51
In general, all cost-effectiveness analyses reviewed were based on evidence that community water
fluoridation is effective in preventing or reducing cavities and that there are no treatment costs
attributable to any adverse health effects associated with the practice. The analyses assumed that caries
would increase if community water fluoridation were ceased.
Analyses that accounted for estimated treatment savings found that for all but the smallest communities,
community water fluoridation remained cost-saving under a wide range of reasonable assumptions
regarding baseline caries risk and the effectiveness of community water fluoridation (Birch 1990; Griffin,
Jones, & Tomar 2001; Wright, Bates, Cutress, & Lee, 2001 The study which best met criteria for
validity both in terms of study quality and applicability to our local situation was the 2001 report by
Griffin et al. of the Centers for Disease Control and Prevention (CDC). They estimated per capita cost
savings each year from community water fluoridation in larger communities from $3.52 to $33.71 in 1995
U.S. dollars, depending on baseline caries risk and estimated effectiveness of water fluoridation (Griffin,
Jones & Tomar, 2001).
Estimation of Local Cost-Effectiveness Ratio
The cost per unit health benefit produced from water fluoridation can vary by at least a factor of four
according to the underlying level of canes risk in the community, and by a factor of ten depending on the
size of the community served by the distribution system (Birch, 1990). Therefore, local estimates of these
parameters are important. Since there are no local data on baseline caries incidence, the FTSG asked
researchers at the CDC to provide the group with regional estimates from the most recent national survey
of oral health (the National Institute of Dental Research [NIDR] National Survey of the Oral Health of
U.S. School Children, 1986-87), adjusted by estimates of the reduction in caries incidence that might have
occurred since then.
The total costs of community water fluoridation are the direct and indirect costs of fluoridating our water
minus the estimated treatment savings secondary to the fluoridation program (White et al., 1989). The
total direct cost of fluoridating the Fort Collins community water supply has remained fairly constant at
less than a dollar per capita per year since current facilities were constructed in 1993 (Kevin Gertig, City
of Fort Collins Water Department). The annual operating cost (materials, operating costs and
maintenance), estimated to be $57,500 in 2001, has averaged $0.52 per capita and has ranged from $0.41-
$0.65 per capita (adjusted to 2000 dollars) since 1995. These costs are similar to published cost estimates
from other large facilities (Ringelberg, Allen, & Brown, 1992). Given the estimated capital cost of
$500,000 for proposed new equipment with a total useful life of at least 15-20 years, the total annuitized
per capita cost is $0.21-$0.28. Assuming stable annual chemical, operating and maintenance costs per
capita, a mean population of 120,000 over the next 15 years and a useful life of 15 years, the total cost of
continuing fluoridation will be $0.96 per capita per year through 2023. Applying a discount rate of 4%
and estimating opportunity cost of the capital investment at 4% compounding interest, the average present
value of per capita costs is $0.76 in 2000 dollars.
Drs. Griffin et al. using our projections of local fluoridation costs, calculated mean decay increments from
the most recent national survey of school children in Region V (Texas, Oklahoma, New Mexico, and
Colorado) and calculated cost-benefit estimates according to the analysis of Griffin et al. 2001. Adjusting
for inflation and the 2000 population age distribution of Fort Collins, the estimated net costs per capita
per year if community water fluoridation were discontinued were estimated to be $4.253. To account for
uncertainties regarding the estimates of local caries rates from regional survey data collected over a decade
ago, Griffin conducted a sensitivity analysis using least and most favorable estimates of caries increment
and fluoridation effectiveness. Applying these estimates, averted cost savings could be as little as $3.22 per
person per year and as high as $10.31 per person per year if Fort Collins suspends water fluoridation. (See
Appendix 3, Table 1 for complete report.)
3 Adjusted to the 2000 CPI-dental for U.S. cities.
52 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Griffin writes:
"Community water fluoridation actually saves Fort Collins money. Fort Collins has
approximately 100,968 residents who benefit from community water fluoridation. 4-Using
data on caries increment from Region V of the National Survey of the Oral Health of U.S.
School Children [2] and cost data specific to Ft. Collins, the annual cost savings per
person from community water fluoridation equals $4.25 (year 2000 US$). Thus after
netting out the amortized capital costs as well as annual operating expenses, the annual
cost savings to the.Fort Collins community attributable to community water fluoridation
would be approximately $429,000 (2000 US$). Because we did not have caries data
specific to Ft. Collins we allowed caries increment to vary between the 1986-1987
estimates for the U.S. adjusted for the secular decline in caries (best-case scenario)
and the 1986-1987 Region V estimates adjusted for the secular decline in caries (worst-
case scenario). Our findings suggest that the annual cost savings to the Ft. Collins
community could vary from $325,000 to $1,041,000" (Griffin, personal communication,
July 3, 2002).
Approximately half of these costs would be personal out of pocket costs (Centers for Disease Control and
Prevention [CDC], 2001b, p. 21). Of the remainder, a portion would be subsidized through local, state and
federal taxes funneled through Medicaid, Child Health Plan Plus, and the Health District dental program.
Some local data exist to evaluate the impact of community water fluoridation on costs of publicly
subsidized dental care. The Colorado Department of Public Health and Environment (CDPHE) Oral
Health recently asked state Medicaid to compare the mean annual cost of all professional dental services
for Medicaid eligible children in Larimer County (the large majority of eligibles live in fluoridated
Loveland and Fort Collins) with those in nonfluoridated Logan County in 2001 (personal communication,
Bilmson, June 25, 2002). The goal was to replicate a study from Louisiana published in the Center for
Disease Control's (CDC) Morbidity and Mortality Weekly Report (Water fluoridation and costs of
Medicaid treatment for dental decay - Louisiana, 1995-6. CDC, 1999).
The sample was all Medicaid enrolled children in 2001. They found that 1) only 24% of all children
eligible for Medicaid at any time during the year received any dental services during the year in either
county, and 2) that the average annual cost of dental services per child receiving any dental care was 20%
higher in nonfluoridated Logan County ($396 per child) than in mostly fluoridated Larimer County ($329
per child). The weakness in this assessment is that all services were included (not just caries treatment)
and all children were included, not just those with lifetime residence. Both of these factors would tend to
attenuate the apparent effect of increased caries incidence and treatment. The difference in cost on a per
child basis was $67, a cost-that is borne by taxpayers.
The assumptions of the Griffin et al. model are as follows:
• Cost savings applies to permanent teeth only.
• All decay is eventually treated.
• Benefits of community water fluoridation are topical and post-eruptive (i.e., start at age six for
permanent teeth).
• Benefit is constant, non-cumulative and accrues only to community residents.
• Costs and benefits are discounted at 4%.
• The discounted cost of treating decay in the future is no less than the cost of treating it when it
appears.
4 According to the 2000 Census Fort Collins had 100,968 residents, aged 6 to 64 years. According to
Griffin [1] water fluoridation has been shown to be effective in reducing tooth decay in the permanent
dentition of individuals, aged 6 to 64 years.
Finding #3: Costs and Benefits, Including the Distribution of Costs and Benefits 53
• Simple amalgam fillings will always be used and require replacement with single surface fillings
every 12 years until age 65. Potentially costlier treatments (composite fillings, root canals, crowns,
bridges) and related treatments (i.e., for periodontal disease related to fillings) are not included.
• Dental fees are the same as the cost of resources to provide the services ($54 for single surface
amalgam filling).
• Productivity costs averted were limited to one hour at average hourly wage ($18) for filling a
cavity.
• Costs due to adverse effects of community water fluoridation are negligible.
• Fluoride from sources other than toothpaste and community water fluoridation are controlled for.
• The population of 6-64 year olds will remain fixed at 2000 levels.
• Suspending water fluoridation increases caries rates by the percentage equal to the relative
difference in mean caries rates between fluoridated and nonfluoridated communities (adjusted for
estimated decline in caries since then) according to the 1986-87 NIDR National Survey of the
Oral Health of U.S. School Children.
Most of these assumptions would tend to under-estimate the potential costs of suspending fluoridation.
For instance, fluoridation is believed to reduce caries in primary (baby) as well as permanent teeth, (and
has been found to be effective in reducing root caries, an increasing problem for seniors (CDC, 2001b, p.
11). Weakening of tooth structure from accumulated treated caries, a problem that often leads to more
expensive restorations or extractions and loss of function, is not accounted for in this analysis. Because of
the "halo effect," fluoridation of Fort Collins water may also benefit those outside the community who
ingest foods and beverages processed with city water. Griffin, Gooch, Lockwood and Tomar (2001) have
shown that those living in nonfluoridated communities in regions where water fluoridation is widespread
experience substantial caries reductions. Finally, the non-monetized benefits of an averted decayed
surface-i.e., the pain and dysfunction that accompanies active untreated decay-might make fluoridation
worthwhile even if there were no net savings to the program.
Uncertainties Regarding Cost-Effectiveness of Water Fluoridation
Several assumptions used in published cost-effectiveness analyses could, if incorrect, lead to over-
estimations of cost-savings. First, costs of potential adverse effects of water fluoridation are assumed to
be negligible. The only adverse health effect (presently known) for which there is greater than very low
risk is enamel fluorosis. None of the cost-effectiveness analyses reviewed estimated costs of enamel
fluorosis. While fluorosis is thought to be caused primarily by the early use or over use of fluoridated
toothpaste and the inappropriate use of fluoride supplements, absolute levels of enamel fluorosis, mostly
of the very mild-to-mild form, are still higher in communities with fluoridated water. Using McDonagh et
al. (2000) estimate of the prevalence of fluorosis of aesthetic concern (12.5%) and Lewis and Banting's
(1994) estimate of attributable fraction (39%) (see Finding #2), nearly 5% (12.5% X 39%) of lifetime
residents in a fluoridated community will have enamel fluorosis attributable to water fluoridation that may
be of aesthetic concern. Some people (generally those with moderate to severe mottling involving the
anterior teeth) choose to modify this condition with elective treatment. The definitive treatment for
moderate enamel fluorosis of aesthetic concern and severe fluorosis is application of a porcelain veneer or
porcelain to metal crown (median charge $662 and $875 per tooth, respectively). Because the treatment is
elective, and the "need" subjective, it would be difficult to estimate the number of people who would
choose such treatment nor are estimates available of the number who currently receive it. Furthermore, it
is uncertain whether or not levels of fluorosis of aesthetic concern decrease when a community stops
fluoridating. Even if these treatment costs could be estimated, they do not include intangibles such as
reduced self-esteem. Based on these concerns, the FTSG concluded that not considering the costs of
enamel fluorosis might lead to over-estimation of the cost-savings of water fluoridation.
As noted in Finding #2, the FTSG did not find conclusive evidence of any other adverse effects of
optimally fluoridated water, but identified some gaps in knowledge (see' Finding#2). If increased risk of
54 Report of the Fort Collins Fluoride Technical Study Group - April 2003
bone fractures, cancers or other adverse health effects were in fact real, they would have a substantial
impact on the cost effectiveness of water fluoridation.
Also, if baseline caries risk in Fort Collins is substantially lower than the conservative estimates used in
this analysis (see Appendix 3), and if the diffusion effect of foods and beverages shipped in from
fluoridated areas sufficiently buffers the loss of drinking water fluoride, the net expense of suspending
fluoridation will be lower (at least from the perspective of the Fort Collins community).
Cost savings were calculated based on the use of hydrofluorosilicic acid (HFS), which is commonly used in
community water fluoridation. However, questions have been raised by some members of the public about
the safety of using this material, and they have requested that sodium fluoride be used instead. If the
calculation were performed incorporating the higher cost of using sodium fluoride, the cost savings would
be less.
Finally, using results of the Griffin analysis to estimate the net cost of suspending water fluoridation in the
City of Fort Collins also presumes that changes in the behavior of dentists or consumers of dental products
will not result and that caries levels will increase. In fact, as discussed in Finding #1, behaviors may change
and caries levels may not increase. Some studies have found indications of increased use of preventive
dentistry and use of alternative sources of fluoride in fluoridation-ended communities (Maupome, Clark,
Levy, & Berkowitz, 2001; Kunzel, Fischer, Lorenz, & Bruhmann, 2000; Kunzel & Fischer, 1997). To the
extent that these less cost-effective approaches are being substituted for a more cost-effective approach,
caries rates may increase less than the analysis predicts, but net costs are likely to be higher.
Distributional Effects of Community Water Fluoridation
Because the Fort Collins Water Utility is operated as an enterprise fund, all costs-both operating and
capital costs-are borne by customers of the Water Utility in proportion to the amount of domestic water
used. The benefits are distributed to all those who live and drink water in the community, as well as those
who ingest foods and beverages produced with community water. Fluoride modalities may be most effective
and therefore cost-effective for persons at highest risk for caries. The risk factors for caries include (CDC,
200Ib, p. 5):
• lower socio-economic status,
• lower levels of parent education,
• those without access to or who do not seek dental care, and
• individual factors.'
Numerous studies in the U.S. and elsewhere have found that the distribution of caries in a community is
skewed, with caries experienced much higher among children and adults in lower socioeconomic strata
(SES) than those in higher SES groups (CDC, 2001b, p. 5; CDC, 2001a, p. 2)
"Eighty percent of dental caries identified in pennanent teeth of children aged 5-17 years in the
United States occur in 25% of children (4,6,7). Lower-income, Mexican American and African-
American children and adults have more untreated decayed teeth than their higher-income or non-
Hispanic white counterparts (4,5,8,9). Among low-income children, approximately one third have
untreated caries in primary teeth that could be associated with pain, difficulty in eating, and
underweight (9)" (CDC, 2001a).
(4, 5, 6, 7, 8, 9) References within a quote are available in the source document.
Active caries, history of caries in siblings or care-givers, gingival recession, high levels of cariogenic
bacteria, impaired ability to maintain oral hygiene, malformed enamel or dentin, decreased salivary
flow, radiation treatment, low salivary buffering capacity, space maintainers/ oral appliances or dental
prostheses and consumption of refined sugars. '
Finding #3: Costs and Benefits, Including the Distribution of Costs and Benefits 55
The reasons for this discrepancy are probably multifactorial. Many factors can contribute to high rates of
caries in low-income populations:
"Low indices of socioeconomic status (SES) have been associated with elevations in caries,
although the extent to which this indicator may simply reflect previous correlates is unknown.
Low SES is also associated with reduced access to care, reduced oral health aspirations, low self-
efficacy, and health behaviors that may enhance caries risk" (National Institute of Health, Office
of the Director, Consensus Statement [VIII], 2001, p. 12).
All "Tier One" references that addressed the issue of the impact of community water fluoridation on
different socioeconomic groups observed that lower SES groups would be more likely to benefit from
community water fluoridation, thereby reducing the disparity in oral health and increasing equity (CDC,
2001b, p. 11; USPHS, p. 28; NHS Centre for Reviews and Dissemination, University of York, 2000, p.
33; Spencer, Slade, & Davies 1996; Locker, 1999, p. 4).
However, the recent systematic review conducted by the University of York for the British National
Health Service found the quality and quantity of evidence addressing this issue to be lacking. As reviewed
by Medical Research Council of Great Britain:
"The York Review concluded that there appears to be evidence that water fluoridation
reduces the inequalities of dental health across the social classes in five and twelve year
olds using the dmft/DMFT measure. This effect was not seen in the proportion of caries
free children among five-year olds; the data on caries prevalence in children of other ages
also did not demonstrate an effect. The review suggested caution in interpreting these
results because of the small quality of studies, differences between the studies, and their
low quality rating" (Medical Research Council, 2002, p. 21).
Effectiveness and Cost-Effectiveness of Other Fluoride Modalities Relative
to Community Water Fluoridation
Laboratory research suggests that maintenance of constant low levels of fluoride in the oral cavity is most
effective at reducing caries (World Health Organization [WHO] 1994, p. 1). The WHO Expert Committee
on Oral Health Status and Fluoride Use concluded that the goal of a community-based caries prevention
program should be to implement the most appropriate means of maintaining a constant low level of
fluoride in as many mouths as possible" (WHO, 1994 p. 1). One of the key advantages cited by public
health authorities for water fluoridation, when compared to other possible strategies for delivering
fluoride to the oral cavity, is that it does not require behavioral changes from its recipients, and that those
most likely to benefit from it will do so (CDC, 2001b, p. 11). Both the WHO committee and the CDC's
Fluoride Recommendations Work Group found that, provided a community had a piped water supply,
community water fluoridation is the most effective method of reaching the whole population.
There are, however, a wide variety of other methods to deliver fluoride to the oral cavity. To the extent that
they supply frequent low-level exposures of fluoride to the mouth, they will yield similar caries reductions
(see Appendix 3, Table 3). However they differ in their applicability to community-based interventions, in
the degree to which they depend on individual behavior changes, in how logistically difficult it is to target
them to needy members of the community and in their cost (see Appendix 3, Table 3).
School-based water fluoridation systems and classroom mouth rinse programs are amenable to a
community-based approach and have been shown to be effective, but the former are logistically difficult
and neither of these approaches benefits adults. Costs of school water fluoridation range from $1 to $14
per student/year (CDC, 200 lb, p. 23). The expense of mouth rinse programs comes not from the materials
but from the weekly or monthly supervision that is required. Risks of fluorosis in school-based programs
56 Report of the Fort Collins Fluoride Technical Study Group - April 2003
would be expected to be low since children 6 years and older are generally past the age of fluorosis
susceptibility (CDC, 2001b, pp. 12 & 16 In several European countries, fluoridated salt (analogous to
iodized salt) is widely available as a caries reducing agent (WHO, 1994, pp. 20-21). Because it is not
available in the U.S., it is not a feasible option in our community.
Fluoride toothpaste has been shown in high quality studies to be safe, effective and inexpensive in older
children and adults at reducing caries, but has been found to be an important cause of enamel fluorosis in
young children due to inadvertent swallowing. According to the CDC, "Children who begin using
fluoride toothpaste at age <2 years are at higher risk for enamel fluorosis than children who begin later or
who do not use fluoride toothpaste at all" (CDC, 2001b, p. 14).
Dietary fluoride supplements (tablets, lozenges, liquids) have been used for caries prevention since the
1940s, but the evidence for their effectiveness is mixed (CDC, 200Ib, p. 16; WHO, 1994, p. 23).
Supplements are designed to be used in settings of fluoride-deficient drinking water, but studies have
found their use in fluoridated communities to be common-7% to 35% in studies reviewed by the
Fluoride Recommendations Work Group (CDC, 2001b, p. 16). There is good evidence for the association
between use of supplements and the development of enamel fluorosis (see Finding #2). Fluoride
supplements are inexpensive but they require a prescription and the dosage schedule is complex,
particularly for parents with children of different ages (WHO, 1994, p. 24).
Professionally applied fluoride compounds include gels, foams, and varnishes. They have an effectiveness
similar to that of community water fluoridation and the risk for fluorosis is reported to be low (CDC,
2001 b, pp. 17-18). They require professional application at six-month intervals and therefore are the least
cost-effective method of delivery. Pit and fissure sealants have also been shown to be effective as long as
the sealants are maintained (see Appendix 3, Table 4) (NIH, 2001, p. 15). Sealants and fluoride modalities
are complementary approaches to caries prevention, since topical fluoride is less effective at preventing
caries on the pit and fissure surfaces than on the smooth surfaces of teeth.
There is very little data on the relative cost-effectiveness of these other methods of caries prevention.
Recently, the Fluoride Recommendations Work Group compared what is known of the effectiveness and
cost-effectiveness of the various methods of fluoride delivery (CDC, 2001b, pp. 21-24). The results are
summarized in the second column of Table 3 in Appendix 3. The costs of the fluoride material alone are
higher for toothpaste, mouth rinse, supplements and professionally applied compounds than the entire per
capita cost of community water fluoridation. To those material costs one must add the costs of promoting
the health behavior. Kay and Locker (1998) conducted a systematic review of the effectiveness of health
promotion programs aimed at oral health. They reported that there are no established cost-effective
methods for reliably bringing about the personal use of fluoride. Oral health promotion delivered at the
dentist's office was most effective, but was most expensive. According to this review, school-based
brushing programs and mass media programs have not been shown to be effective (Kay & Locker, 1998).
School-based sealant delivery programs, were found to be effective and were "strongly recommended" by
the Task Force on Community Preventive Services (CDC, 2001 a, p. 9). Under some circumstances, these
programs may be cost-saving (Zabos et al., 2002).
Considering the effectiveness and costs of the various modalities discussed above, the CDC expert panel
recommended community water fluoridation in all areas of the U.S. and fluoride toothpaste, used as
directed, for all persons. Other fluoride modalities were recommended only for certain high-risk
individuals and only after consultation with their dentist or health care provider (CDC, 2001b, pp. 26-27).
To meet the public health challenge presented by dental caries, the U.S. Department of Health and Human
Services outlined the goals for community water fluoridation as part of the Healthy People 2000 and
2010. These national health goals include objectives to increase national baseline fluoridation level to
75% of the U.S. population served by community water systems from the 1989 and 1992 levels of 61 and
62% (CDC, 2002 p.144.) The Centers for Disease Control and Prevention states, "Fluoridation of the
Finding 43: Costs and Benefits, Including the Distribution of Costs and Benefits 57
public water supply is the most equitable, cost-effective, and cost-saving method of delivering fluoride to
the community" (CDC, 2002, p. 144).
Other effective caries modalities are in current use in other countries to prevent caries. Examples include
fluoridated salt (France, Germany, Switzerland, and others), fluoridated milk, and use of xylitol-
containing chewing gum (Hayes, 2001). Fluoridated salt and milk are not available in the U.S. Xylitol-
containing gum is available in the U.S. and regular use has been shown in one study in Finland to be
similar in cost and effectiveness to school-based sealant programs in that country (Alanene, Holsti, &
Pienihakkinen, 2000). However, cost-effectiveness data are not available for the U.S., thus its application
as a public health strategy is unclear.
FINDINGS: Costs and Benefits
The research indicates that the public health goal of a reduction in the incidence of caries is better
achieved through community water fluoridation than through individual approaches. It requires minimal
behavioral changes compared to alternative delivery methods. It is effective in reaching people in all
socioeconomic strata.
The FTSG finds that, even in the current situation of widespread use of fluoride toothpaste and lower
baseline caries risk, it is likely that community water fluoridation remains effective and cost saving at
preventing dental caries. Based on best available evidence, suspending fluoridation of water in Fort
Collins would yield a net increase in costs of preventing and treating caries approximately $4.25 per
person per year (range $3.22 - $10.31.) The burden of caries is disproportionately borne by those with
lower socio-economic status. There is some evidence that water fluoridation reduces this inequality in
oral health.
Not considering the costs of enamel fluorosis or other potential adverse health effects may have led to an
over-estimation of the cost-savings of water fluoridation in Fort Collins. The magnitude of the costs of
adverse effects is likely to fall well below the estimated net savings.
In summary, this cost analysis assumes that there is a significant benefit from community water
fluoridation in preventing caries and potential adverse health effects are not significant. The analysis also
assumes that the city will continue using current fluoride additives (hydrofluorosilicie acid). Using this set
of assumptions, there appears to be a net cost benefit to community water fluoridation. If any of these
assumptions are not valid the cost-benefit picture could change significantly.
The FTSG did not review any study or measure that will achieve the same levels of prevention as water
fluoridation for the same resources.
58 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Reference List
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caries prevention. Acta Odonologica Scandinavica, 58(6), 279-284.
Birch, S. (1990). The relative cost effectiveness of water fluoridation across communities: analysis of
variations according to underlying caries levels. Community Dental Health, 7(1), 3-10.
Brunson, D. (Diane Brunson [diane_brunson@state.co.us]). Medicaid Dental Cost County Comparison
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Burt, B.A., ed. (1989). Proceedings for the workshop: cost-effectiveness of caries prevention in dental
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Centers for Disease Control and Prevention. (1999). Water fluoridation and costs of Medicaid treatment
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recommendations of the task force on community preventive services. Morbidity and Mortality
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Centers for Disease Control and Prevention. (2001b). Recommendations for using fluoride to prevent and
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Fluoride: Benefits and Risks: Report of the subcommittee on fluoride of the EHPC. Public Health
Service, Department of Health and Human Services.
Davies, G.N. (1973). Fluoride in the prevention of dental caries: a tentative cost-benefit analysis. British
Dental Journal, 135, 131-134.
Griffin, S. (sigl@ede.gov). Fort Collins community water fluoridation cost-effectiveness estimates. E-
mail to: MD Bruce Cooper (bcooper@healthdistrict.org). 2002 Jul 3.
Griffin, S.O., Gooch, B.F.;-Lockwood, S.A., & Tomar, S.L. (2001). Quantifying the diffused benefit
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Kunzel, W. & Fischer, T. (1997). Rise and fall of caries prevalence in German towns with different F
concentrations in drinking water. Caries Research, 31(3), 166-173.
Finding #3: Costs and Benefits, Including the Distribution of Costs and Benefits 59
Kunzel, W., Fischer, T., Lorenz, R., & Bruhmann, S. (2000). Decline of caries prevalence after the
cessation of water fluoridation in the former East Germany. Community Dentistry & Oral
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Medical Research Council. (2002). Working Group Report: Water Fluoridation and Health. London, UK:
Medical Research Council.
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156-168.
Ringelberg, M.L.; Allen, S.J., & Brown, L.J. (1992). Cost of fluoridation: 44 Florida communities.
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13(Supp12), 27-37.
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community water fluoridation. Journal Dentistry Education, 53(11), 646-657.
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Fluoride Use. WHO Technical Report Series, No. 846 ed. Geneva, Switzerland: World Health
Organization; 1994.
Wright, J.C., Bates, M.N., Cutress, T., Lee, M. (2001). The cost-effectiveness of fluoridating water
supplies in New Zealand. Australia and New Zealand Journal of Public Health, 25(2), 170-178.
Zabos, G.P., Glied, S.A., Tobin, J.N., Amato, E., Turgeon, L., Mootabar, R.N. et al. (2002). Cost-
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38-48.
60 Report of the Fort Collins Fluoride Technical Study Group - April 2003
Finding #4 - The Potential for Increased Contaminant Levels Due to
the Use of Hydrofluorosilicic Acid
The Fluoride Technical Study Group's (FTSG) review identified three potential concerns associated with
hydrofluorsilicic acid (HFS.):
1. co-contamination (i.e. arsenic and lead),
2, decreased pH leading to increased lead solubility or exposure, and
3. potential toxicological effects from incomplete dissociation products of HFS.
Background
The City of Fort Collins has fluoridated its treated water supply since 1967. The form of fluoride added
from 1967 to 1992 was called Sodium Silicofluoride, which is a dry product. As the Water Treatment
Facility continued to expand, a liquid form of fluoride called Hydrofluorosilicic Acid (HFS) has been
utilized since 1993. Liquid forms of fluoride are easier to handle due to the size of larger treatment
facilities. The levels of fluoride are monitored carefully at the Water Treatment Facility and throughout
the distribution system, and meet or exceed all recommendations set forth by the Colorado Department of
Public Health and Environment (CDPHE) and the U.S. Centers for Disease Control and Prevention (CDC).
Fluoride Sources
The City of Fort Collins Utilities currently fluoridates its water with a chemical called Fluorosilicic Acid.
The chemical is sometimes called Hydrofluorosilicic Acid (HFS). The term `HFS' will be used in this
report. The product is shipped to Fort Collins by truck from any one of several points in the United States.
The form used in Fort Collins is typically a 23 - 24% aqueous solution of HFS (H2SiF6) and has a formula
weight of 144.08. HFS in its frill strength, non-diluted form is corrosive and requires special handling
considerations. The Fort Collins Utilities complies with all special handling requirements as stated in the
Material Safety Data Sheet included in Appendix 4.1.
Fluoride Manufacturing Process
All of the fluoride chemicals used in the United States for water fluoridation (sodium fluoride, sodium
fluorosilicate, and HFS) are byproducts of the fertilizer industry. The process diagram of how fluorides
are obtained during the manufacture of phosphoric acid is shown in Appendix 4.2, Figures 1 and 2.
Methods of Application
Fort Collins utilizes a liquid feed system to apply the optimum level of fluoride at all times. The
equipment consists of the unloading station, bulk tank, day tank, pumping system, and flow measurement
system. The system is monitored around the clock, 365 days per year. The amount of fluoride added is
determined by measuring the background fluoride concentration in the raw (untreated) water supply.
Typical background levels range from <0.15 - 0.25 mg/L of fluoride (Figure 1). Once the background
levels are established, the amount of fluoride added is set to maintain the desired optimal range of 0.7 -
1.2 mg/L of fluoride. Fort Collins Utilities ensures that the amount of fluoride added is at the optimum
level (1.0 mg/L) as recommended by the CDPHE and the U.S. Environmental Protection Agency (EPA).
(See Report Form 1 in Appendix 4.3)
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicic Acid 61
Fluoride in Morsetooth Raw Woter
JatOS" - May 2001
I
Ox I
02S
k~
O.a.K -
00f1
.y N in r, r~ m m a e e N es n n r ! N N N IA r- r. m m w ai ea
.!w .w m - b )n A+ 4S m SA PO 9' 0 Or P. T P m 0+ pS>+ a o
.n ..i .ii N Ill ~i1 N vl u1 u5 ul N N vi N .,y 41 •'1 N of N N N N N uw N N vl ifi 1/i Y_y LL~1
YZ 4:7
Figure 1.
Daily samples of water are measured in the City of Fort Collins Water Treatment Facility Process
Laboratory (Figure 2). The analytical methods used are the specific electrode method (Standard Methods
for the Examination of Water and Wastewater, 19'h edition, 4500-F C). In addition to routine sampling for
the raw and finished water, samples are analyzed throughout the city for many different parameters. See
the Fort Collins Utilities Drinking Water Consumer Confidence Report, 2001 at
httn://fcgov.com/water/12di%wgr2001.pdf and in Appendix 4.4). At all times, on-line monitoring
equipment alert operators to any change in feed rates for chemical addition.
Daily Fluoride Concentration at Sample Station #2
APR-02
1.4D
J 1.20 - - -
E 1.00
y 0.60
0.60 - - - -
0 0.40
LL. 0.20
-
0.00
a a a a a a n n a a. a n a a a
a a a g a a a a a a g a a a 4
M ~ r r r r m M t+~l N N M
Fluoride Mean+3SD - Mean-3SD -Mean
Figure 2.
62 Report of the Fort Collins Technical Study Group - April 2003,
Split samples are conducted on a routine basis between Fort Collins Utilities Water Quality Laboratory,
the Fort Collins Utilities Process Lab and the CDPHE. The Fort Collins Utilities Water Quality
Laboratory is a CDPHE and EPA certified laboratory and all data for quality assurance is reviewed on an
annual basis. Results are reported to the CDPHE on a monthly basis (see Report Form 1 in Appendix 4.3).
Water Quality
The Fort Collins Water Treatment Facility uses a number of chemicals in the water treatment process to
treat the raw untreated water. All of the chemicals used at the facility must meet specific industry
accepted quality standards. Two of the standards utilized by Fort Collins Utilities are 1) American Water
Works Association (AWWA) and 2) National Sanitation Foundation Standard 60 for Water Treatment
(NSF) which can be found at www.nsf.org.
Upon receiving each load of HFS, the Fort Collins Utilities samples the product and runs a specific
gravity test to verify the solution strength. Samples are stored for further analytical verification if warranted.
As per industry standards, inorganic chemistry analyses are not routinely performed on each shipment. Each
shipment requires a certification assuring compliance for each load (see NSF Certification in Appendix 4.4).
The FTSG found that the vendor used by the City of Fort Collins meets or exceeds the standards set forth by
AWWA and the NSF. In addition to chemical standards, the City of Fort Collins must comply with
standards set forth by the EPA. The City of Fort Collins complies with all regulations and in many cases
exceeds the minimum requirements (see Appendix 4.5 - Fort Collins Utilities Drinking Water Consumer
Confidence Report, 2001 also available at http://fcgov.com/water/pdf/wv 01.pdf).
Analytical Information
The FTSG reviewed data from the City of Fort Collins Water Quality Laboratory with respect to its
Annual Water Quality Summary. Summaries for 2001 and 2002 are included in Appendix 4.6 and are
available at http://fcgov.com/water/pdf/200Iwgt.pdf.
Data is shown for Arsenic and Lead (Figures 3 and 4). Other parameters evaluated were Iron, Copper,
Manganese, Zinc, Cadmium, Molybdenum, and Nickel. These can be found in Appendix 4.7 as Figures 3
- 9. These data represent values collected each week for a period from January 1997 - 2001. This data set
was chosen for figures that are based on mean values for weekly samples for the time period indicated.
Along with other water quality parameters, the FTSG reviewed each inorganic constituent in regards to
trends or changes. The FTSG reviewed data for pH in the untreated and finished water and one
distribution system site (Poudre Valley Hospital) as well (Figure 5).
The following graphs represent the values for the raw water, finished water, and the Maximum
Contaminant Level (MCL) or the Secondary Maximum Contaminant Level (SMCL) for each parameter
shown. For a description on MCL and SMCLs, please refer to the Consumer Confidence Report located
in Appendix 4.
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicie Acid 63
Arsenic Concentrations FCU WO Lab data 79977
60 50
50 _
w. 40
A 30 - - - - is
01 j
Yttt
20
NeH MCL J 0 _ i \t
~ I
• 2.0 2.0 2. V 2.0
0
Poudre Raw H.T. Raw Finished PVH SMCL
(SS#2}
Figure 3. Arsenic
Fort Collins monitors its treated water regularly for arsenic, lead and other potential contaminants. Figure
3 shows the concentration of Arsenic (As) in both sources of raw, untreated water, the finished drinking
water, Poudre Valley Hospital (PVH), and the SMCL is for arsenic. The EPA maximum concentration
level for arsenic is 50 ug/literl, but has been reduced to 10 ug/liter effective in 2006 due to the fact that
arsenic is a recognized human carcinogen.
The levels of 2.0 ug/L shown on the chart are the detection limits of the test instruments for arsenic. The
concentration of arsenic in the source waters is below the detection limit for arsenic of 2.0 ug/L. The
concentration in the finished water is also below the detection limit of 2.0 ug/L. Because arsenic levels
are below the detection limits both before and after the addition of HFS, the actual changes in arsenic
concentrations are not measurable.
In response to citizen concerns, Fort Collins Utilities had a single batch ofHFS tested on May 17, 2001
using EPA Method 200.7 at the Utility's Pollution Control Laboratory. This laboratory scored 100%
accuracy on all analytes of the 2001 EPA required DMR-QA "unknown" performance audit samples. In
this sample, the HFS measured contained 29.0 mg/L arsenic. In addition, an analytical result from one
former supplier (PENCO, Inc.), measured in 1993, indicated an arsenic concentration of 61 mg/L. The
FTSG estimated the effect of the addition of arsenic contained in HSF on the concentration of arsenic in
the finished water (Arsenic Concentration in Finished Water in Appendix 4.8). Using these two measures
(29.0 mg/L and 61 mg/L) and conservative assumptions regarding the analytical method and the volume
dilution, it was estimated that the additional contribution to the arsenic concentration in finished water is
approximately between 0.10 ug/L to 0.24 ug/L (or 0.10 ppb to 0.24 ppb2).
50 ug/L is approximately equivalent to 50 part per billion (50 ppb). In other words 50
ug/liter is similar to saying the MCL is fifty "drops" of arsenic in one billion "drops" of water.
z 0.10 or 0.10 ppb is approximately equal to saying "one tenth of a "drop" of arsenic in one billion "drops" of
water. The range could be interpreted as saying there is between one tenth to one quarter of a drop of arsenic in
one billion drops of treated water"
64 Report of the Fort Collins Technical Study Group - April 2003
Lead Concentrations FcuWO Laeaaiai~-zo~
I~
16 - 15
14
a; 12 - -
10
g
2 4 - - 'r -i
2 -
Poudre Raw H.T. Raw Finished PVH MCL
(SS#2)
Figure 4. Lead
Lead (Pb) levels for both source waters, Fort Collins Utilities finished drinking water, Poudre Valley
Hospital (PVH), and the MCL are shown in Figure 4. The concentration of lead in the source waters is
below the detection limit for lead in the department's laboratory of 1.0 ug/liter. Because lead levels are
below the detection limits both before and after the addition of HFS, the actual changes in lead
concentrations are not measurable.
Fort Collins Utilities implemented a corrosion control program in 1983 and maintains pH levels in
finished water leaving the treatment facility at values of 7.8 to 8.0 (acidic is 6.9 and lower, neutral is 7.0
and alkaline is 7.1 and above). As shown in Figure 5, the addition of HFS at the amount applied is not
decreasing pH to an acidic level that could be corrosive to plumbing materials.
FCU wq Lab dale in- 2D02
pH Concentrations
9.00
8.50 - Alkaline
= 8.00 - - X86
M
_ 7.51
-CL
7.50 - 7_39- -
7.00 - - F- Neutral
CO ~i
6.50
Acidic
6,00 - - -
j Poudre Raw H.T. Raw Finished (SS#2)
Figure 7. pH
Finding 04 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicic Acid 65
UNCERTAINTIES
Safety of Hydrofluorosilicic Acid
Members of the public have raised concerns that HFS has not been adequately tested for safety in
experimental animals since virtually all of the initial testing in animals was done with sodium fluoride.
The National Toxicology Program (NTP) continuously solicits and accepts nominations for toxicological
studies to be undertaken by the program on substances of potential human health concern. Nominations
can come from Federal agencies, industry, the public, and other interested parties and undergo several
stages of review before selections for testing are made. Possible public health consequences of exposure
are the overriding factors considered in selecting substances. Nominations are first reviewed internally
and toxicological summaries based on an extensive literature review are prepared. The summary is then
distributed to the NTP Interagency Committee for Chemical Evaluation and Coordination (ICCEC). The
ICCEC is composed of representatives from the Agency for Toxic Substances and Disease Registry, the
Consumer Product Safety Commission, the Department of Defense, the Environmental Protection
Agency, the Food and Drug Administration's National Center for Toxicological Research, the
Occupational Safety and Health Administration, the National Cancer Institute, the National Institute of
Environmental Health Sciences, the National Institute for Occupational Safety and Health, and the
National Library of Medicine. Evaluation by the ICCEC is the initial external review step. The ICCEC
makes testing recommendations and priorities. These recommendations are presented to the NTP Board
of Scientific Counselors (BSC) for review and comment in an open public session. The BSC's
recommendations are then submitted to the NTP Executive Committed for review and final approval
(Federal Register: March 2, 2000, Volume 65, Number 42, pp. 11329-1133 1).
HFS was nominated to the NTP by Mr. Coplan (of Masters and Coplan) and other private individuals in
2001 for "chemical characterization, toxicological characterization including chronic toxicity,
carcinogenicity, neurotoxicity, and toxicokinetics, [and] mechanistic studies related to cholinesterase
inhibition and lead bioavailability." According to the toxicological summary for nomination, "Sodium
hexafluorosilicate and fluorosilicic acid were nominated for toxicological testing based on their
widespread use in water fluoridation and concerns that if they are not completely dissociated to silica and
fluoride in water that persons drinking fluoridated water may be exposed to compounds that have not
been thoroughly tested for toxicity." On April 17, 2002, the ICCEC recommended, "chemical
characterization studies to assess chemical fate under aqueous conditions. Toxicological studies may be
considered when results of chemical characterization studies are available for review" (Federal Register:
June 12, 2002,Vol. 67, No. 113, pp. 40329 -40333). The nomination is now in the hands of the NTP
Board of Scientific Counselors.
The public concern that HFS has not been tested for toxicity can be addressed by a better understanding
of the chemical fate of fluorosilicate drinking water additives as presented by a review by Urbansky in
2002. Quickly upon addition to water supplies, HFS reaches an equilibrium where, according to Urbansky
(2002, p. 2843), "the hexaflurosilicate molecule is totally decomposed to a silicic acid molecule, four
hydrogen cations and six fluoride anions." Furthermore, the "dissolved silica contribution of the
fluoridating agent is trivial compared to the native silica" (Urbansky, 2002, p. 2844). Complicated
fractional distribution plots for fluoride species as a function of pH presented by Urbansky (2002)
illustrate the proportion of each species at equilibrium. The conclusion drawn by Urbansky from a review
of these diagrams are that "The concentration of any fluorosilicate species is extremely small at drinking
water pH"(Urbansky, p 2844). For example:
"It is concluded that in any drinking water supply with a pH of 5 or higher, fluoridated with
sodium silicofluoride [HFS] to the extent of 16 ppm of F or less, all of the silicofluoride is
completely hydrolyzed to silicic acid, fluoride ion, and hydrogen fluoride. There can be no
question of toxicity of SiF4 or SiF6-2 under such conditions" (Urbansky, pp. 2844 & 2845).
66 Report of the Fort Collins Technical Study Group - April 2003
While Urbansky states (2002, p. 2850) that, "The kinetics of the dissociation and hydrolysis of
hexafluorosilicate are poorly understood from a mechanistic or fundamental perspective." the take home
message by Urbansky for non-chemists is that, "the rate data suggest that equilibrium should have been
achieved by the time the water reaches the consumer's tap if not by the time it leaves the waterworks
plant" (Urbansky, 2002, p. 2850). So while further research is being conducted on this subject, Urbansky
states on page 2851, "we must try to make the best use of the information available to us and focus oil the
consistencies as well as what is unequivocally established as chemical fact." The Urbansky review
suggests that fears over HFS and the unknown toxicity of any resulting fluoride species as the HFS
quickly dissociates to fluoride ion and the other chemical species may be unfounded when the
fundamental chemical facts are considered.
On April 25, 2002, the EPA released a request for research on the hexafluorosilicates in a Request For
Assistance (RFA).
"The primary objective of this RFA is to investigate the reactions that take place when
fluorosilicates are added to drinking water supplies and what concentrations of which
fluorosilicate species may monitored in finished drinking water supplies and what techniques may
be used for such monitoring" (The RFA is issued under the name of Edward T. Urbansky, U.S.
EPA, National Risk Management Research Laboratory Water Supply and Water Resources
Division).
Potential for Increased Absorption of Lead
Studies published in 1999 and 2000 of 280,000 children in Massachusetts and 151,000 children in New
York showed an increase in the prevalence of blood lead concentrations in children's blood in
communities in which fluorosilicates [HFS] were used for community water fluoridation (Masters &
Coplan, 1999; Masters, Coplan, Hone, & Dykes, 2000). The increases were from 1.9% above 10 ug/dl, to
29% above 10 ug/dl. The 1999 study (Masters & Coplan) concluded "the fluoridation agents used in
water treatment have a major effect on lead levels in children's blood." They found that lead levels were
significantly lower in communities that used sodium fluoride, or did not fluoridate, than those who used
silicofluorides (SiF) such as hydrofluorosilicic acid (Masters & Coplan, p. 440).
The study published in 2000 concluded, "For every age/race group, there was a consistently significant
association of SiF treated community water and elevated blood lead." In addition, they found poor black
children in old housing to be at a higher risk of elevated blood lead if their community provided
silicofluoride-treated water (Masters, Coplan, Hone, et al., 2000).
Because of the ecologic design of the Master's studies, the possibility that the findings are due to
confounding cannot be ruled out. The data show that 49.4% of the homes in communities treated with
silicofluorides were built before 1939. Conversely, 23.3% of the homes in the communities not treated
with silicofluorides were built before 1939. Similarly, 22.3% of the children in silicofluoride-treated
communities were below the poverty level while 8.5% of children in non-silicofluoride treated
communities were below the poverty level. The method of analysis in the Masters, Coplan, Hone, et al
(2000) paper relied on classifying covariates as above and below the median for each risk factor,
potentially resulting in misclassification of exposure to the confounder (e.g. poverty) by inclusion of large
numbers of subjects in the category considered exposed to the confounder. In addition, the age of the
house in which the child resided and the age of the water distribution system infrastructure would be
expected to differ across communities characterized by differences in age of housing. There is therefore a
possibility of differences in lead containing piping through the distribution system. There also may be
differences in exposure to household sources of lead. For example, the increased tendency of poor or
malnourished children to chew on objects such as window-sills, to eat dirt, and to mouth objects
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicic Acid 67
potentially contaminated with lead flakes from chipped paint. These differences are not accounted for in
the analysis and may have been responsible for the differences observed in blood lead concentrations.
A possible mechanism proposed by Masters and Coplan (1999, p. 437) for the putative increase in lead is
the lowering of drinking water pH by addition of HFS (a strong acid) in poorly buffered water supplies
leading to a pH dependent increase in lead solubility (Stumm & Morgan, 1996). This mechanism is only
plausible for poorly buffered water supplies such as those studied by Masters et al. The Fort Collins water
supply is maintained at a well buffered pH greater than 7(neutral to alkaline), as shown in figure 5, and as
such lead solubility should not be increased through the addition of small amounts of HFS. To the extent
that the mechanism of lead increase is due to HFS induced changes in pH and therefore lead solubility,
Fort Collins drinking water lead concentrations are not susceptible to this reported side effect of HFS
addition.
No other plausible biological/chemical mechanism for the source of the increases in blood lead has been
proposed in the literature. Studies with stronger designs would be needed to fully address any remaining
uncertainties.
The Medical Research Council of Great Britain stated the following:
"Two recent studies (Masters & Coplan, 1999; Masters, et al., 2000) have found an association
between ingestion of drinking water treated with silicofluorides and elevated blood lead in
children.... However, according to the US EPA there is no substantive evidence to suggest that
fluoridation of drinking water with any fluoridating chemical increases the concentration or
bioavailability of lead in drinking water via chemical reactions in the plant, the distribution system,
the home plumbing system, or the human body itself (Urbansky & Schock, 2000). This appears to be
a controversial area and further studies are awaited" (Medical Research Council Working Group,
2002, p. 36).
Peer review of the Masters and Coplan report, coming at the request of US EPA and Urbansky, has
confirmed Urbansky and Schock's critique. The peer review letters are included as Appendix 4:X to this
report.
Lead Levels in Colorado Children
The issue raised by a pair of papers by Masters and Coplan - that exposure to HSF in drinking water
might be a risk factor for elevated lead levels in children - could make information regarding the
prevalence of elevated blood lead levels in children in our area relevant to decision makers. The Colorado
Board of Health recommends that all low-income children in Colorado should be routinely screened for
blood lead levels at 12 months and 24 months of age or between the ages of 36 months and 72 months of
age if they have not been previously screened (Colorado Childhood Blood Lead Screening Plan, CDPHE,
2001). Low-income children are identified as children eligible for Medicaid, Child Health Plan Plus, or
the Colorado Resident Discount Program, and children residing in certain areas in Denver found to be
high risk. A report released in April 2002 by the Colorado Department of Public Health and Environment
Lead Poisoning Prevention Program reports that the proportion of children with one or more elevated
blood lead levels (>_10 mcg/dl) in the period 1/1996 through 12/2001 was 1.5% (95% C.T., 0.8%-2.1%) in
Larimer County, one of the lowest proportions among the ten largest counties in Colorado (see Table 1).
Statewide, the proportion of children tested who were found to have elevated blood lead levels was 2.7%
(95% C.I., 2.5%-2.9%) during this period. It is important to note that this data represents only a fraction
68 Report of the Fort Collins Technical Study Group - April 2003
of children defined as high risk3 and may not be representative of all low-income high risk children.
However, the proportion of all children in our community with elevated lead levels would be expected to
be lower than those reported above. Masters and Coplan reported elevated lead levels from a survey of
children 0-6 years old in Massachusetts in 1991, based on the fluoridation status of community of
residence. Lead levels were elevated in 3.0%, 2.9%, 1.6% and 1.9% of communities fluoridated with
silicofluoride compounds (SFC), hydrofluorosilicic acid (HFS), sodium fluoride and no fluoride,
respectively.
Mean lead levels have been decreasing since the late 1970s attributed primarily to the phase-out of leaded
gasoline. A national sample of children ages 1 to 5 years found a decrease from 2.7 (95% C.I., 2.6-2.9)
mcg/dl in 1991-94 to 2.0 (95% C_I., 1.7-2.3) in 1999 (MMWR. 49(50):1133-7, Dec 2000).
In recent years the most common source of lead in children with elevated lead levels is from lead based
paint that is poorly maintained in older homes. Low-income children living in older housing have been
found to be at much higher risk of elevated blood lead levels than other children (CDC, Blood lead levels
in young children-United States and selected states, 1996-1999, MMWR 49(50):1133-7). In Larimer
County (see Table 1) there are a relatively low proportion of residences deemed high-risk-defined as
"housing unit built before 1950 and occupied by a low income family" (based on 1990 US Census data,
see http://www.scorecarti.oi-g
Table 1
Blood Lead Levels In Colorado Counties, 1996-2001
% Of
_ % of 6-72 housing % of % of
Count ° X10 Est. 95% C.Ib month units with population
y # 10 Total /o . 95/o . olds high-risk populationd on HFS or
Ng/dla testsa Ng/dl screeneda of lead on Fl water SFCd
hazards'
Adams 20 546 - 3.7% 2.1%,5.2% 0.4% 0.7% 15% 11%
Arapahoe 48 1787 2.7% 1.9%,3.4% 1.1% 0.3% 64% 64%
Boulder 17 563 3.0% 1.6%,4.4% ? 1.4% 92% 90%
Denver 461 17362 2.7% 2.4%,2.9% 7.8% 5.7% 100% 100%
ELPaso 26 1849 1.4% 0.9%,1.9% 1.3% 1.2% 8% 3%
Jefferson 20 798 2.5% 1.4%,3.6% 0.7% 0.4% 44% 43%
Larimer 20 1376 1.5% 0.8%,2.1% 3.4% 1.7% 95% 94%
Mesa 14 471 3.0% 1.4%,4.5% 2.6% 2.7% 98% 98%
Pueblo 34 972 3.5% 2.3%,4.7% 1.8% 6.4% 89% 87%
Weld 74 2518 2.9% 2.3%,3.6% 2.4% 3.8% 76% 74%
Childhood Lead Poisoning in Colorado, Colorado Department of Public Health And Environment, April 2002
(http i/wW\4_.CC~p]]~ala1C GO.US/l~Cll////,J/Leadlsurvbu11e12.PDf)
d 95% confidence intervals were calculated using a normal approximation to the binomial distribution assuming a random sample
of n = "total tests".
`Environmental Defense Fund, Scorecard, Colorado Counties http:/1www.scorecard.org!), based on 1990 Census data.
d Personal Communication, Dan Felzien, Fluoride Engineer, Colorado Department of Public Health and Environment, 3/2003.
HFS: hydrofluorosilicic acid; SFC:silicofluoride compounds.
The data for statewide blood levels exceeding 10 pg/dl are important to the considerations by the FTSG
and decision makers for several reasons:
3 In the 3`d quarter of 2001 in Larimer County, approximately 3,725 of 18,527 6-72 month olds met the definition of
high-risk based on Medicaid or CHP enrollment (20%). Of these about 1,850 would have been eligible for a lead test
in 2001 (became either 12 or 24 months of age). However only 622 children were screened (34%).
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicic Acid 69
1. They provide information about childhood blood levels and community water fluoridation and
other conditions that may affect blood lead that are relevant to our local conditions. Local
conditions include age of housing, use of lead piping in distribution and household water systems,
use of lead paint, and socio-economic and demographic factors.
2. The data from CDPHE can be screened on an ecologic basis, similar to the approach taken by
Masters and Coplan (1999, 2000) in their analyses of blood lead in Massachusetts, New York and
elsewhere. Masters and Coplan conducted their analyses at the community level (not on
individuals). In Colorado, the analysis is done at the county level with the available data.
From a qualitative basis, there is a lack of association between community water fluoridation with HFS
and the percent of children with blood lead > 10 pg /dl. The highest prevalence of elevated blood lead is
seen in Adams County (3.7%) where 11% of the population receive HFS fluoridated water. Larimer
County and El Paso County have the lowest prevalence of elevated blood lead (1.4% and 1.5%,
respectively). El Paso County (containing Colorado Springs) has high naturally occurring concentrations
of fluoride in their water supply and most communities within the county (including Colorado Springs) do
not use community fluoridation. Larimer County, similar in many aspects to El Paso County (e.g. the
percent of housing with high risk lead hazards is 1.7% and 1.2%, respectively) also has a very low
prevalence of elevated blood lead, and provides 94% of its population with water fluoridated with HFS.
Qualitatively, there is a lack of relationship between community fluoridation with HFS and blood lead in
the data for these two counties. The lack of relationship between HFS and blood lead in these two
counties would not be expected to occur if the hypothesized association as postulated by Masters and
Coplan was causal.
From a quantitative perspective, the data in Table 1 can be subjected to regression analyses to determine
whether there is evidence of a statistical association between child blood lead and use of HFS at the
county level. The results of our analyses are provided in Appendix 4. The r-squared value provides a
measure of the variation in the dependent variable (prevalence of elevated blood lead) explained by the
independent variable 1IFS treated water or % of housing units with high-risk lead hazards). The
county analysis for percent of population supplied by HFS shows no relationship (r-squared = 1.9%, p >
0.7). The analysis for % of housing units with high-risk lead hazards also shows very little correlation (r-
squared = 8.8%, p > 0.4). When both variables are placed in the model, the r-squared is 8.9%, p > 0.7.
The partial correlation coefficient was calculated to estimate the degree of correlation between elevated
blood lead and the % of population supplied by HFS, controlling for % of housing units with high-risk
lead hazards. This analysis shows no significant correlation (r-squared =0.12%, p >0.9) between elevated
childhood blood lead and percent of the population receiving HFS treated water in Colorado counties.
These data have been adjusted for potential confounding by the percent of housing with high-risk lead
housing in each county. There were no data available to evaluate other potential confounders such as age
and race.
70 Report of the Fort Collins Technical Study Group - April 2003
FINDINGS: The Potential for Increased Contaminate Levels Due to the Use
of Hydrofluorosilicic Acid
The FTSG's review identified three potential concerns associated with hydrofluorosilicic acid (HFS): 1.)
co-contamination (i_e. arsenic and lead), 2.) decreased pH leading to increased lead solubility or exposure,
and 3.) potential toxicological effects from incomplete dissociation products of HFS. The FTSG used the
raw and finished water quality data for the City of Fort Collins to determine whether the addition of HFS
was responsible for the potential addition of contaminants such as heavy metals to the city's drinking
water. There were no evidence that the addition of HFS increased the concentrations of copper,
manganese, zinc, cadmium, nickel, or molybdenum. The concentrations of arsenic and lead were below
the detection limit for the Fort Collins Water Quality Control Laboratory in both the source water and the
finished water and below the maximum contaminant level (MCL) for these naturally occurring elements.
There was no evidence that the introduction of HFS changed the pH of the water appreciably. Concern
that HFS incompletely disassociates may be unfounded when the fundamental chemical facts are
considered. Therefore, it is unlikely that community water fluoridation poses a health risk from the
exposure to any of these chemicals present in the water as it leaves the plant. Further studies related to the
health effects of HFS are in progress.
Finding #4 - The Potential for Increased Contaminant Levels Due to the Use of Hydrofluorosilicic Acid 71
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72 Report of the Fort Collins Technical Study Group April 2003
APPENDIX A-1
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80 Report of the Fort Collins Fluoride Technical Study Group - April 2003