A COHORT STUDY OF THYROID-DISEASE IN RELATION TO FALLOUT FROM NUCLEAR-WEAPONS TESTING

Objective.-To estimate individual radiation doses and current thyroid disease status for a previously identified cohort of 4818 schoolchildren potentially exposed to fallout from detonations of nuclear devices at the Nevada Test Site between 1951 and 1958. Design.-Cohort analytic study. Setting.-Communities in southwestern Utah, southeastern Nevada, and southeastern Arizona. Participants.-Individuals who were still residing in the three-state area (n=3122) were reexamined in 1985 and 1986, and information on the subjects' and their mothers' milk and vegetable consumption during the fallout period was obtained by telephone interview (n=3545). After exclusions to eliminate missing data and confounding factors, 2473 subjects were available for analysis. Main Outcome Measures.-Individual radiation doses to the thyroid were estimated by combining consumption data with radionuclide deposition rates provided by the US Department of Energy and a survey of milk producers. Relative risk models adjusted for age, sex, and state were fitted using maximum likelihood to period prevalence data for thyroid carcinomas, neoplasms, and nodules. Results.-Doses ranged from 0 mGy to 4600 mGy, and averaged 170 mGy in Utah. There was a statistically significant excess of thyroid neoplasms (benign and malignant; n=19), with an increase in excess relative risk of 0.7% per milligray. A relative risk- for thyroid neoplasms of 3.4 was observed among 169 subjects exposed to doses greater than 400 mGy. Positive but nonsignificant dose-response slopes were found for carcinomas and nodules. Conclusions.-Exposure to Nevada Test Site-generated radioiodines was associated with an excess of thyroid neoplasms. The conclusions are limited by the small number of exposed individuals and the low incidence of thyroid neoplasms.