National Cancer Institute EMBARGOED FOR RELEASE 1:00 p.m. EDT Friday, August 1, 1997 FOR RESPONSE TO INQUIRIES NCI Press Office (301) 496-6641 Press Release NCI Releases Results of Nationwide Study of Radioactive Fallout from Nuclear Tests The National Cancer Institute (NCI) today released summary results from a study to assess Americans' exposures to radioactive iodine-131 fallout from atmospheric nuclear bomb tests carried out at the Nevada Test Site in the 1950s and 1960s. A full report is to follow. Depending on their age at the time of the tests, where they lived, and what foods they consumed, particularly milk, Americans were exposed to varying levels of I-131 for about two months following each of the 90 tests. Because I-131 accumulates in the thyroid gland, concerns have been raised that the fallout could cause thyroid cancer in people who were exposed to it as children. The average cumulative thyroid dose to the approximately 160 million people in the country at the time was about 2 rads. (By comparison, a routine I-131 diagnostic thyroid scan of a child in the 1950s gave approximately 200 to 300 rads to the thyroid. Today, a thyroid scan would give about 0.4 to 4 rads to the thyroid, depending on the radionuclide used.) NCI urges caution in interpreting the results, particularly because the study does not directly address the question of cancer risk from the fallout. NCI and the Department of Health and Human Services have enlisted the help of the foremost radiation experts in the country to fully evaluate the risk and develop an appropriate public health response. The Department has requested that the National Academy of Sciences' Institute of Medicine (IOM) review the data to assess whether risks can be determined, and to recommend to physicians how to identify, evaluate, and treat persons who might be at risk of disease because of their exposure to radioactive iodine. In the meantime, persons concerned about fallout exposure should consult a health professional. The IOM review -- which will be comprehensive and public as are all IOM studies -- is expected to take about six months after final arrangements are made. IOM is expected to establish a diverse expert panel. In addition, the administration will establish an interdepartmental group to look at broader policy issues. Persons living in heavy fallout areas, children, and persons who drank large quantities of milk might have received higher doses. In general, those living in Western states to the north and east of the test site had the highest doses. Most children aged 3 months to 5 years probably received three to seven times the average dose for the population in their county, because in general they drank more milk than adults, and because their thyroids were smaller. By contrast, most adults probably received two to four times less than the average county dose. An executive summary and a technical summary of the report are being released today. The executive summary describes the results in nontechnical language, and lists the 24 U.S. counties with the highest average cumulative exposures from all 90 tests combined. The technical summary includes descriptions of the methods and formulas used in data collection and analysis. Also being released today is a list of estimated average thyroid dose levels for each county in the 48 contiguous states. These documents are all available on NCI's World Wide Web site http://rex.nci.nih.gov, in the "What's New" link. A narrative summary of the data, about 1,000 pages long, and the full data set, about 100,000 pages long, will be released by Oct. 1. This full data set contains tables and maps with exposure data for each of the 90 individual tests and for persons in 13 age categories, based on four different scenarios of milk consumption, in each county. In 1982, Congress passed legislation calling for the Department of Health and Human Services to develop methods to estimate I-131 exposure, to assess thyroid doses of I-131 received by individuals across the country from the Nevada tests, and to assess risks for thyroid cancer from these exposures. The fallout report fulfills the first two of these three requirements. The report was not intended to fulfill the third requirement, risk assessment. To estimate thyroid cancer risk, the results of the report will be linked with findings from relevant epidemiological studies, including some currently in progress. The limited data on persons exposed as children to I-131 from the nuclear test fallout have provided suggestive but not conclusive evidence that it is linked to thyroid cancer. The radiation doses received by young children who lived in areas with high fallout levels, particularly those who drank a great deal of milk, may well have increased the risk of thyroid cancer. The level of increased risk is highly uncertain. To provide more accurate information on the risk of thyroid cancer from radioactive fallout, NCI investigators are collaborating with other U.S. government agencies, international organizations, and governments and scientists in Belarus and Ukraine to study thyroid cancer among persons exposed to fallout from the Chernobyl nuclear accident in 1986. A clear increase in thyroid cancer has been seen in this population. In 1997, an estimated 16,100 Americans will be diagnosed with thyroid cancer and 1,230 will die from the disease. The incidence rate for women is more than twice as high as that for men. Thyroid cancer is highly curable: The 5-year survival rate is about 95 percent. NOTE: National Cancer Institute scientists will be available for questions through a media briefing call, scheduled from 2-3 p.m. Friday, August 1. The number to call is 1-800-288-8967. This will be similar to a conference call, in which all callers can hear all questions and answers. A tape of the call will be available by calling the same number (1-800-288-8967) beginning one hour after the conference call ends. (For example, if the conference call ends at 3:07 p.m., the tape will be available beginning at 4:07 p.m.). Callers should tell the operator they would like to hear the replay of the Aug. 1 NCI media briefing call. The tape will be available at that number until 11:59 p.m. Tuesday, Aug. 5. Maps from the fallout study are available in Macintosh four-color format for unlimited editorial use via the Digital News Service (DNS). To download the graphics from the DNS, use your computer modem to call (800) 467-3992. The graphics can be found in the Health section folder. For assistance with the DNS, contact Steve Alexander at (202) 973-5868.