Advisers to the Nation on Science, Engineering, and Medicine

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council.

www.national-academies.org

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Assessing the Human Health Risks of Trichloroethylene: Key Scientific Issues (2006)

New Source Review for Stationary Sources of Air Pollution (2006)

Human Biomonitoring for Environmental Chemicals (2006)

Health Risks from Dioxin and Related Compounds: Evaluation of the EPA Reassessment (2006)

State and Federal Standards for Mobile-Source Emissions (2006)

Superfund and Mining Megasites—Lessons from the Coeur d’Alene River Basin (2005)

Health Implications of Perchlorate Ingestion (2005)

Air Quality Management in the United States (2004)

Endangered and Threatened Species of the Platte River (2004)

Atlantic Salmon in Maine (2004)

Endangered and Threatened Fishes in the Klamath River Basin (2004)

Cumulative Environmental Effects of Alaska North Slope Oil and Gas Development (2003)

Estimating the Public Health Benefits of Proposed Air Pollution Regulations (2002)

Biosolids Applied to Land: Advancing Standards and Practices (2002)

The Airliner Cabin Environment and Health of Passengers and Crew (2002)

Arsenic in Drinking Water: 2001 Update (2001)

Evaluating Vehicle Emissions Inspection and Maintenance Programs (2001)

Compensating for Wetland Losses Under the Clean Water Act (2001)

A Risk-Management Strategy for PCB-Contaminated Sediments (2001)

Acute Exposure Guideline Levels for Selected Airborne Chemicals (4 volumes, 2000-2004)

Toxicological Effects of Methylmercury (2000)

Strengthening Science at the U.S. Environmental Protection Agency (2000)

Scientific Frontiers in Developmental Toxicology and Risk Assessment (2000)

Ecological Indicators for the Nation (2000)

Waste Incineration and Public Health (1999)

Hormonally Active Agents in the Environment (1999)

Research Priorities for Airborne Particulate Matter (4 volumes, 1998-2004)

The National Research Council’s Committee on Toxicology: The First 50 Years (1997)

Carcinogens and Anticarcinogens in the Human Diet (1996)

Upstream: Salmon and Society in the Pacific Northwest (1996)

Science and the Endangered Species Act (1995)

Wetlands: Characteristics and Boundaries (1995)

Biologic Markers (5 volumes, 1989-1995)

Review of EPA’s Environmental Monitoring and Assessment Program (3 volumes, 1994-1995)

Science and Judgment in Risk Assessment (1994)

Pesticides in the Diets of Infants and Children (1993)

Dolphins and the Tuna Industry (1992)

Science and the National Parks (1992)

Human Exposure Assessment for Airborne Pollutants (1991)

Rethinking the Ozone Problem in Urban and Regional Air Pollution (1991)

Decline of the Sea Turtles (1990)

Copies of these reports may be ordered fromthe National Academies Press

(800) 624-6242 or (202) 334-3313

www.nap.edu

Review of the Department of Defense Research Program on Low-Level Exposures to Chemical Warfare Agents (2005)

Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants, Volume 1 (2004)

Spacecraft Water Exposure Guidelines for Selected Contaminants, Volume 1 (2004)

Toxicologic Assessment of Jet-Propulsion Fuel 8 (2003)

Review of Submarine Escape Action Levels for Selected Chemicals (2002)

Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals (2001)

Evaluating Chemical and Other Agent Exposures for Reproductive and Developmental Toxicity (2001)

Acute Exposure Guideline Levels for Selected Airborne Contaminants, Volume 1 (2000), Volume 2 (2002), Volume 3 (2003), Volume 4 (2004)

Review of the US Navy’s Human Health Risk Assessment of the Naval Air Facility at Atsugi, Japan (2000)

Methods for Developing Spacecraft Water Exposure Guidelines (2000)

Review of the U.S. Navy Environmental Health Center’s Health-Hazard Assessment Process (2000)

Review of the U.S. Navy’s Exposure Standard for Manufactured Vitreous Fibers (2000)

Re-Evaluation of Drinking-Water Guidelines for Diisopropyl Methylphosphonate (2000)

Submarine Exposure Guidance Levels for Selected Hydrofluorocarbons: HFC-236fa, HFC-23, and HFC-404a (2000)

Review of the U.S. Army’s Health Risk Assessments for Oral Exposure to Six Chemical-Warfare Agents (1999)

Toxicity of Military Smokes and Obscurants, Volume 1(1997), Volume 2 (1999), Volume 3 (1999)

Assessment of Exposure-Response Functions for Rocket-Emission Toxicants (1998)

Toxicity of Alternatives to Chlorofluorocarbons: HFC-134a and HCFC-123 (1996)

Permissible Exposure Levels for Selected Military Fuel Vapors (1996)

Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants, Volume 1 (1994), Volume 2 (1996), Volume 3 (1996), Volume 4 (2000)

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In 1986, the U.S. Environmental Protection Agency (EPA) established a maximum-contaminant-level goal (MCLG) of 4 milligrams per liter (mg/L) and a secondary maximum contaminant level (SMCL) of 2 mg/L for fluoride in drinking water. These exposure values are not recommendations for the artificial fluoridation of drinking water, but are guidelines for areas in the United States that are contaminated or have high concentrations of naturally occurring fluoride. The goal of the MCLG is to establish an exposure guideline to prevent adverse health effects in the general population, and the goal of the SMCL is to reduce the occurrence of adverse cosmetic consequences from exposure to fluoride. Both the MCLG and the SMCL are nonenforceable guidelines.

The regulatory standard for drinking water is the maximum contaminant level (MCL), which is set as close to the MCLG as possible, with the use of the best technology available. For fluoride, the MCL is the same as the MCLG of 4 mg/L. In 1993, a previous committee of the National Research Council (NRC) reviewed the health effects of ingested fluoride and EPA’s MCL. It concluded that the MCL was an appropriate interim standard, but that further research was needed to fill data gaps on total exposures to fluoride and its toxicity. Because new research on fluoride is now available and because the Safe Drinking Water Act requires periodic reassessment of regulations for drinking water contaminants, EPA requested that the NRC evaluate the adequacy of its MCLG and SMCL for fluoride to protect public health. In response to EPA’s request, the NRC convened the Committee on Fluoride in Drinking Water, which prepared this report. The committee was charged to review toxicologic, epidemiologic, and clinical data on fluoride,

particularly data published since 1993, and exposure data on orally ingested fluoride from drinking water and other sources. Biographical information on the committee members is provided in Appendix A.

This report presents the committee’s review of the scientific basis of EPA’s MCLG and SMCL for fluoride, and their adequacy for protecting children and others from adverse health effects. The committee considers the relative contribution of various sources of fluoride (e.g., drinking water, food, dental hygiene products) to total exposure, and identifies data gaps and makes recommendations for future research relevant to setting the MCLG and SMCL for fluoride. Addressing questions of economics, risk-benefit assessment, or water-treatment technology was not part of the committee’s charge.

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: Kenneth Cantor, National Cancer Institute; Caswell Evans, Jr., University of Illinois at Chicago; Michael Gallo, University of Medicine and Dentistry of New Jersey; Mari Golub, California Environmental Protection Agency; Philippe Grandjean, University of Southern Denmark; David Hoel, Medical University of South Carolina; James Lamb, The Weinberg Group Inc.; Betty Olson, University of California at Irvine; Elizabeth Platz, Johns Hopkins Bloomberg School of Public Health; George Stookey, Indiana University School of Dentistry; Charles Turner, University of Indiana; Robert Utiger, Harvard Institute of Medicine; Gary Whitford, Medical College of Georgia; and Gerald Wogan, Massachusetts Institute of Technology.

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by John C. Bailar, University of Chicago, and Gilbert S. Omenn, University of Michigan Medical School. Appointed by the NRC, they were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.

The committee gratefully acknowledges the individuals who made presentations to the committee at its public meetings. They include Paul Con-

nett, St. Lawrence University; Joyce Donohue, EPA; Steve Levy, University of Iowa; William Maas, Centers for Disease Control and Prevention; Edward Ohanian, EPA; Charles Turner, Indiana University; and Gary Whitford, University of Georgia. The committee also wishes to thank Thomas Burke, Johns Hopkins University; Michael Morris, University of Michigan; Bernard Wagner, Wagner and Associates; and Lauren Zeise, California Environmental Protection Agency, who served as consultants to the committee.

The committee is grateful for the assistance of the NRC staff in preparing the report. It particularly wishes to acknowledge the outstanding staff support from project director Susan Martel. We are grateful for her persistence and patience in keeping us focused and moving ahead on the task and her expertise and skill in reconciling the differing viewpoints of committee members. Other staff members who contributed to this effort are James Reisa, director of the Board on Environmental Studies and Toxicology; Kulbir Bakshi, program director for the Committee on Toxicology; Cay Butler, editor; Mirsada Karalic-Loncarevic, research associate; Jennifer Saunders, research associate; and Tamara Dawson, senior project assistant.

Finally, I would like to thank all the members of the committee for their efforts throughout the development of this report.

John Doull, M.D., Ph.D., Chair

Committee on Fluoride in Drinking Water

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FLUORIDE IN DRINKING WATER

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