EXPOSURE OF THE AMERICAN PEOPLE TO IODINE-131 FROM NEVADA NUCLEAR-BOMB TESTS

Review of the National Cancer Institute Report and Public Health Implications

Committee on Thyroid Screening Related to I-131 Exposure

Board on Health Care Services

INSTITUTE OF MEDICINE

and

Committee on Exposure of the American People to I-131 from the Nevada Atomic Bomb Tests

Board on Radiation Effects Research

Commission on Life Sciences

NATIONAL RESEARCH COUNCIL

NATIONAL ACADEMY PRESS
Washington, D.C.
1999



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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications EXPOSURE OF THE AMERICAN PEOPLE TO IODINE-131 FROM NEVADA NUCLEAR-BOMB TESTS Review of the National Cancer Institute Report and Public Health Implications Committee on Thyroid Screening Related to I-131 Exposure Board on Health Care Services INSTITUTE OF MEDICINE and Committee on Exposure of the American People to I-131 from the Nevada Atomic Bomb Tests Board on Radiation Effects Research Commission on Life Sciences NATIONAL RESEARCH COUNCIL NATIONAL ACADEMY PRESS Washington, D.C. 1999

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications NATIONAL ACADEMY PRESS 2101 Constitution Ave., N.W. Washington, D.C. 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. The Institute of Medicine and the National Research Council act under the 1863 congressional charter for the National Academy Sciences to advise the federal government. They also act on their own initiative to identify important scientific and health issues. The president of the Institute of Medicine is Dr. Kenneth Shine. The president of the National Research Council is Dr. Bruce Alberts. Support for this project was provided by the U.S. Department of Health and Human Services (Contract Number NO1-OD-4-2139, TO 35). The views presented are those of the National Research Council and Institute of Medicine committees and are not necessarily those of the funding organization. Library of Congress Catalog Card No. 98-83159 International Standard Book No. 0-309-06175-X Additional copies of this report are available from: National Academy Press 2101 Constitution Avenue, N.W. Box 285 Washington, D.C. 20055 Call 800-624-6242 (or 202-334-3313 in the Washington metropolitan area) Internet: www.nap.edu Copyright 1999 by the National Academy of Sciences. All rights reserved. Printed in the United States of America

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications INSTITUTE OF MEDICINE COMMITTEE ON THYROID CANCER SCREENING Robert S. Lawrence, Chair, Professor of Health Policy and Associate Dean for Professional Education, Johns Hopkins University Catherine Borbas, Executive Director, Healthcare Education and Research Foundation, Inc., Minneapolis J. William Charboneau, Professor of Radiology, Mayo Clinic and Mayo Medical School Virginia A. Li Volsi, Vice Chair for Anatomic Pathology, Hospital of the University of Pennsylvania Ernest L. Mazzaferri, Professor and Chair, Department of Internal Medicine, Ohio State University Stephen G. Pauker, Vice Chair for Clinical Affairs, Department of Medicine, New England Medical Center Henry D. Royal, Associate Director, Division of Nuclear Medicine, Mallinckrodt Institute of Radiology, Washington University School of Medicine Samuel A. Wells, Professor of Surgery, Washington University School of Medicine Steven H. Woolf, Private Practice, Family Medicine and Professor, Department of Family Practice, Virginia Commonwealth University Staff Marilyn J. Field, Co-Study Director and Deputy Director, Health Care Services, IOM Cecilia Rossiter, Administrative Assistant, IOM Vince Knobel, Project Assistant, IOM Kay Harris, Financial Associate, IOM Clyde Behney, Deputy Executive Officer, IOM

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications COMMITTEE ON EXPOSURE OF THE AMERICAN PEOPLE TO I-131 FROM NEVADA ATOMIC BOMB TESTS William J. Schull Chair, Professor, Human Genetics Center, School of Public Health, University of Texas, Houston Keith F. Baverstock, Head of the Radiation Protection Division, World Health Organization, Rome, Italy Stephen A. Benjamin, Professor of Pathology, Radiological Health Sciences, and Environmental Health, Colorado State University Patricia A.H. Buffler,* Dean and Professor of Epidemiology, University of California, Berkeley Sharon Dunwoody, Professor of Journalism and Mass Communication, University of Wisconsin Peter G. Groer, Associate Professor, Department of Nuclear Engineering, University of Tennessee Robert S. Lawrence,* Professor of Health Policy and Associate Dean for Professional Education, Johns Hopkins University Carl M. Mansfield, Chair, Department of Radiation Oncology, University of Maryland Medical Systems, Baltimore James E. Martin, Associate Professor of Radiological Health, University of Michigan Ernest L. Mazzaferri, Professor and Chair, Department of Internal Medicine, Ohio State University Kathryn Merriam, Synthesis, Incorporated, Pocatello, ID Dade W. Moeller,† Dade Moeller & Associates, New Bern, NC Christopher B. Nelson, Environmental Protection Agency, Washington, DC Henry D. Royal, Associate Director, Division of Nuclear Medicine, Mallinckrodt Institute of Radiology, Washington University School of Medicine Richard H. Schultz, Administrator, Department of Health and Welfare, Boise, ID Daniel O. Stram, Associate Professor of Preventive Medicine, University of Southern California Robert G. Thomas, Kallispell, MT *   IOM member †   NAE member

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications Consultants Lynn R. Anspaugh, University of Utah F. Owen Hoffman, SENES Oak Ridge, Inc., Oak Ridge, Tenn. Donald E. Myers, University of Arizona Roy E. Shore, New York University Medical Center Staff Steven L. Simon, Co-Study Director Karen M. Bryant, Project Assistant Doris E. Taylor, Staff Assistant Catherine S. Berkley, Administrative Associate Evan B. Douple, Director, Board on Radiation Effects Research Paul Gilman, Executive Director, Commission on Life Sciences David M. Livingston, Dana-Farber Cancer Institute, Boston Editor Anne Kelly Sponsor's Project Officer Charles E. Land, National Cancer Institute

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications BOARD ON RADIATION EFFECTS RESEARCH John B. Little, Chair (until June 30, 1998), Harvard School of Public Health, Boston S. James Adelstein* (as of July 1, 1998), Harvard Medical School, Boston Valerie Beral, University of Oxford, United Kingdom Edward R. Epp (as of July 1, 1998), Weston, MA Helen H. Evans (as of July 1, 1998), Case Western Reserve University, Cleveland, OH Maurice S. Fox,†‡ Massachusetts Institute of Technology, Cambridge R.J. Michael Fry, Chair (as of July 1, 1998), Oak Ridge, TN Philip C. Hanawalt† (until June 30, 1998), Stanford University Lynn W. Jelinski, Louisiana State University, Baton Rouge William F. Morgan (as of July 1, 1998), University of California, San Francisco William J. Schull, The University of Texas Health Science Center, Houston Daniel O. Stram, University of Southern California, Los Angeles Susan W. Wallace (until June 30, 1998), University of Vermont, Burlington H. Rodney Withers, University of California Los Angeles Medical Center Staff Evan B. Douple, Director Rick Jostes, Senior Program Officer Steven L. Simon, Senior Program Officer Catherine S. Berkley, Administrative Associate Doris E. Taylor, Staff Assistant Peggy Johnson, Project Assistant (until August 12, 1998) Karen Bryant, Project Assistant (until October 23, 1998) *   IOM member †   NAS member ‡   NAE member

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications INSTITUTE OF MEDICINE BOARD ON HEALTH CARE SERVICES Don E. Detmer, Chair, The University of Virginia Barbara J. McNeil, Vice Chair, Harvard Medical School Stuart H. Altman, Brandeis University, Waltham, MA Paul D. Clayton, Columbia-Presbyterian Medical Center, NY Nancy W. Dickey, Bryan, TX B. Ken Gray, Metroplex Emergency Physician Associates, P.A., Dallas, TX Paul F. Griner, Association of American Medical Colleges, Washington, DC Ruby P. Hearn, Robert Wood Johnson Foundation, Princeton Peter Barton Hutt, Partner, Covington & Burling, Washington, DC Brent C. James, Institute for Health Care, Salt Lake City, UT Jacqueline Kosecoff, Protocare, Santa Monica, CA Sheila T. Leatherman, United Health Care Corporation, Minneapolis John Ludden, Harvard Pilgrim Health Care, Boston Russell L. Miller, Consultant, Washington, DC Mildred Mitchell-Bateman, Huntington Hospital, Huntington, WV Mary Mundinger, Columbia University, New York Uwe E. Reinhardt, Princeton University, NJ Mary Lee Seibert, Ithaca College, Ithaca, NY Gail L. Warden, Henry Ford Health System, Detroit IOM Liaison: Lawrence S. Lewin, The Lewin Group, Fairfax, VA Staff Janet M. Corrigan, Director Marilyn J. Field, Deputy Director Evelyn Simeon, Administrative Assistant

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications COMMISSION ON LIFE SCIENCES Thomas D. Pollard, Chair, The Salk Institute for Biological Studies, La Jolla, CA Frederick R. Anderson, Cadwalader, Wickersham & Taft, Washington, DC John C. Bailar, III, University of Chicago, IL Paul Berg, Stanford University School of Medicine, Palo Alto, CA Joanna Burger, Rutgers University, Piscataway, NJ Sharon L. Dunwoody, University of Wisconsin, Madison John L. Emmerson, Indianapolis, IN Neal L. First, University of Wisconsin, Madison Ursula W. Goodenough, Washington University, St. Louis, MO Henry W. Heikkinen, University of Northern Colorado, Greeley, CO Hans J. Kende, Michigan State University, East Lansing Cynthia J. Kenyon, University of California, San Francisco David M. Livingston, Dana-Farber Cancer Institute, Boston, MA Thomas E. Lovejoy, Smithsonian Institution, Washington, DC Donald R. Mattison, University of Pittsburgh, PA Joseph E. Murray, Wellesley Hills, MA Edward E. Penhoet, Chiron Corporation, Emeryville, CA Malcolm C. Pike, Norris Comprehensive Cancer Center, Los Angeles, CA Jonathan M. Samet, The Johns Hopkins University, Baltimore, MD Charles F. Stevens, The Salk Institute for Biological Studies, La Jolla, CA John L. Vandeberg, Southwest Foundation for Biomedical Research, San Antonio, TX Staff Paul Gilman, Executive Director Alvin G. Lazen, Associate Executive Director (until July 1, 1998) Barbara B. Smith, Administrative Associate Jacqueline K. Prince, Administrative Officer Kit W. Lee, Senior Project Assistant

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications Preface When the atomic weapons testing program in the continental United States began in 1951 at the Nevada Test Site, the world was sharply divided between two conflicting political ideologies with global intentions uncertain to the other. Each saw its political adversary as a potential aggressor, and each launched a major nuclear weapons development and testing program. In both instances, national defense was seen as taking precedence over the possible health hazards that these programs might present either to the individuals directly involved in the development or testing or to the public generally. Governmental decisions related to safety both on and off the Nevada Test Site were undoubtedly influenced by a sense of urgency about national security. One apparent consequence is a history of misleading government statements about the Nevada tests. Government decisions were also shaped by the limited amount of information then available on the potential health hazards of fallout, particularly the later-term effects, such as cancer, that would not be quickly manifested. At the beginning of the test period, the Atomic Energy Commission declared that tests did not present a danger to the public, although some staff expressed concern. Experts were not at that time clearly aware that, in addition to direct radiation exposure and inhalation exposure routes, another exposure route—air-grass-milk—was also important. Not until 1961, near the end of the period of weapons testing did the Federal Radiation Council set as a goal that the annual limit of I-131 doses to the thyroid for a population group not exceed 0.5 rem and that the individual annual limit not exceed 1.5 rem. Although an annual limit of 15 rem had been recommended for members of the public in 1953 (reduced in 1957 to 1.5 rem for minors), the recommendation was not at the time viewed as applicable to fallout from weapons testing. These perceptions of urgency and safety notwithstanding, in retrospect, it is clear that the exposure of the public was inadequately monitored. This has resulted in large uncertainties in the doses the public may have received and has

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications prompted a continuing and often acrimonious debate about the hazards involved and about the release of information about the weapons tests and their consequences. The report released by the National Cancer Institute in October 1997 was an effort to assess the hazards of radioactive iodine (more specifically iodine-131, also written as I-131) from the Nevada weapons tests. The analytic challenges the NCI faced in developing its report were formidable and, of necessity, time consuming to meet. Evaluating and quantifying thyroid cancer attributable to Nevada test fallout is an exceptionally complex task that is beset with immense uncertainties related to both the estimates of I-131 exposure and estimates of I-131 related thyroid cancers. Nonetheless, the credibility of the federal government in matters relating to exposure to ionizing radiation may be have been compromised by the agency's perceived slowness in releasing the report, once the analysis was largely completed. It appears likely that a relatively small proportion of the 160,000,000 Americans alive during the weapons testing program received cumulative doses of iodine-131 greater than the exposure limit set forth in 1961, which would have amounted to 5 rem exposure limit over a ten-year period. However, the number of persons receiving much higher doses, up to 100 rem or more, could have numbered in the tens of thousands. It is the estimation of risk to exposed Americans and the steps that might be taken in response to the risk that has been of primary concern to the review panel established by the Institute of Medicine and the National Research Council. The panel's work focused on (1) assessing the soundness of the NCI analyses and estimates including those developed separately from the main report, (2) the risk of thyroid disease from iodine-131 fallout, (3) evaluating the benefits and harms of recommending a program of routine screening for thyroid cancer, and (4) identifying strategies for communicating with the public about risks and responses. It reaches a somewhat unsettling combination of conclusions, first, that some people (who cannot be easily identified) were likely exposed to sufficient iodine-131 to raise their risk of thyroid cancer and, second, that there is no evidence that programs to screen for thyroid cancer are beneficial in detecting disease at a stage that would allow more effective treatment. To serve the public interest, the major contribution that the government can make is not to launch an ineffective but politically appealing screening program but rather, to develop effective ways to communicate with the public about iodine-131 exposure and health risks and to involve the public in determining what communication strategies people will find understandable, useful, and trustworthy. William J. Schull, Ph.D. Co-Chair Robert S. Lawrence, M.D. Co-Chair

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications Acknowledgments In developing this report, the IOM and NRC committees and staff benefited from the assistance of many individuals and organizations 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 National Research Council'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 participation in the review of this report: Herbert Abrams (Stanford University), Evan J. Englund (Environmental Protection Agency, Las Vegas), Kristine M. Gebbie (Columbia University), H. Jack Geiger (City University of New York Medical School), Prabodh Gupta (Hospital of the University of Pennsylvania), David G. Hoel (Medical University of South Carolina), Bernd Kahn (Georgia Institute of Technology), Russell Brown (Idaho Falls, ID), Richard A. Kerber (University of Utah School of Medicine), Ralph Lapp (Lapp Inc.), Laura Leonard (Handford Health Information Network), Ross L. Prentice (Fred Hutchinson Cancer Center), Morton Rabinowitz (Media, PA), Marvin L. Rallison (University of Utah), David Ransohoff (University of North Carolina at Chapel Hill), Arthur B. Schneider (University of Illinois at Chicago), Lisa Schwartz (Dartmouth Medical School), Harold C. Sox Jr. (Dartmouth-Hitchcock Medical Center), Lee Wilkins (Columbia, MO), and Stephen Woloshin (Dartmouth Medical School). While the individuals listed above have provided constructive comments and suggestions, it must be emphasized that responsibility for the final content of this report rests entirely with the authoring committee and the institution. The NRC committee held several public meetings at which presentations were made and public comments were invited. Appendix A lists those who participated. In addition,

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications the committee appreciates the assistance of Lynn R. Anspaugh (University of Utah), F. Owen Hoffman (Senes, Oak Ridge Inc.), Roy Shore (New York University Medical Center), and Donald E. Myers (University of Arizona) who served as consultants. The IOM committee particularly benefited from the experience and expertise of the presenters and other participants in the workshop the committee convened March 17 and 18 in Washington, DC. Appendix A lists the workshop participants, presenters, and agenda. It also benefited from the timely and thorough review of the scientific literature and other consultation provided by Mark Helfand and Karen Eden. In addition, the committee benefited from the comments of Christopher Merritt, Leslie De Groot, Kenneth Suen, E. Chester Ridgway, and Martin Surks.

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications Contents     EXECUTIVE SUMMARY   1 1   INTRODUCTION   10     Background and Context   10     Historical Overview   11     Origins of Study   14     Overview of Technical Approach and Report Contents   15     Conclusions   16 2   REVIEW OF THE NCI RADIATION DOSE RECONSTRUCTION   17     Basic Assessment   18     Doses and Risks from Other Radionuclides   21     Pathways to Exposure of Humans   21     Sources of Individual Variability in I-131 Dose   23     Estimating the Release and Deposition of I-131   24     From I-131 Deposition on the Ground to Cows' Milk   31     From Fresh Milk to Human Intake   35     From Intake to Thyroid Dose   38     Validation and Uncertainty in Collective or Average Dose Estimates   39     Conclusions   41 3   HEALTH RISKS OF I-131 EXPOSURE   45     Thyroid Gland Biology   45     Radiation and Thyroid Cancer   55     Nonmalignant Thyroid Disease Associated with Radioiodine Exposure   68     Thyroid Cancer Risk Based on NCI Estimates of I-131 Doses   72     Conclusions   81     Addendum 3: Understanding Radiation Risk Factors and Individual Risk   82

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications 4   IMPLICATIONS FOR CLINICAL PRACTICE AND PUBLIC HEALTH POLICY   86     Principles for Screening Recommendations   87     Burden of Illness   90     Thyroid Cancer Screening and Diagnostic Options   93     Accuracy of Screening and Follow-up Tests   95     Benefits and Harms of Screening for Thyroid Cancer   97     Information and Decisionmaking   100     Recommendations of Others   104     Committee Findings and Recommendations   106     Iodine-131 and Thyroid Cancer Information for Physicians [Sample]   113     Conclusions   118     Addendum 4A: Interpreting Sensitivity and Specificity   120     Addendum 4B: Interpretation of Indeterminate and Unsatisfactory FNA Samples   122 5   COMMUNICATING WITH THE PUBLIC ABOUT EXPOSURE TO I-131   125     Characteristics of Risk Communication   126     Can Risk Be Communicated Effectively?   137     Some Important Communication Issues   138     Public Involvement in Explaining Risk   141     Conclusions   144     Addendum 5: Example of a Method to Assist Individuals in Estimating Their Personal Thyroid Cancer Risk   145     How You Can Estimate Your Risk from Exposure to I-131 From Radioactive Fallout During the 1950s   146 6   RESEARCH NEEDS   152     Epidemiology   153     Biology of Radiation-Induced Thyroid Cancer   154     Clinical Practice   155     Risk Communication   155     REFERENCES   157     GLOSSARY   173     APPENDIXES     A.   Study Activities   177 B.   Copy of the Memorandum from Dr. Charles Land to Dr. Richard Klausner   186

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Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications C.   Calculation of Collective Thyroid Dose to the U.S. Population from the Release of 131I from the Nuclear Weapons Tests in Nevada   194 D.   Thyroid Cancer in Idaho, 1970-1996   198 E.   Applicable Radiation Exposure Standards and Guides: Past and Present   214 F.   Screening for Thyroid Cancer: Background Paper   221     COMMITTEE BIOGRAPHIES   264

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