Dose Reconstruction for Exposure to Nevada Test Site I-131
in Utah, Nevada and Arizona

SENES Oak Ridge, Inc., has provided support to the University of Utah to assist in the reconstruction of the models and assumptions used to calculate individual thyroid doses in the "Cohort Study of Thyroid Disease and Radioactive Fallout from the Nevada Test Site." SENES Oak Ridge, Inc. assisted in reprogramming the entire calculation, based on the intent of the authors of the study. The assumptions used in the original study to identify uncertainty shared among individual members of the cohort, as well as the uncertainty unique to each individual, were reevaluated. SENES Oak Ridge, Inc., provided recommendations to upgrade and improve existing models and assumptions to more realistically account for uncertainty. This updated information was used to re-evaluate the association between exposure to I-131 and thyroid cancer.

From 2001 through 2004, the dosimetry system was restored and corrected and all doses were recalculated. In addition, two parameter values were updated. The details of this effort are presented in: Simon, S. L., Anspaugh, L. R., Hoffman, F.O., Scholl, A. E., Stone, M. B., Thomas, B. A., and Lyon, J. L. 2004 Update of Dosimetry for the Utah Thyroid Cohort Study. Radiation Research, 165, 208-222 (2006).

A reevaluation based on corrected dosimetry and medical examination data concluded that persons exposed to radioactive iodine as children have an increased risk of thyroid neoplasms and autoimmune thyroiditis up to 30 years after exposure. Lyon, J. L., Alder, S. C., Stone, M. B., Scholl, A. E., Reading, J. C., Holubkov, R., Xiaoming, S., White, G. L. Jr., Hegmann, K. T., Anspaugh, L., Hoffman, F. O., Simon, S. L., Thomas, B. A., Carroll, R. J., and Meike, A. W. Thyroid Disease Associated With Exposure to the Nevada Nuclear Weapons Test Site Radiation - A Reevaluation Based on Corrected Dosimetry and Examination Data. Epidemiology, 17 (6). 604-614 (2006).


In the Nevada Test Site (NTS) Thyroid Disease Study, the Berkson measurement errors are correlated within dose strata. The following paper considers the problem of risk estimation where there is a complex mixture of classical and Berkson errors, and in which the Berkson errors are correlated within distinct strata of individual doses. Li, Y., Guolo, A., Hoffman, F. O., and Carroll, R. J. Shared Uncertainty in Measurement Error Problems, with Application to Nevada Test Site Fallout Data. Biometrics. 63, 1226-1236 (2007).