The public health implications of combined exposure to multiple sources of 131I released during the Cold War Era: Extension of dose reconstruction to risk analysis and beyond

During the past 15 years, doses have been reconstructed to members of the public who were exposed to radiation released from Cold War Era government facilities that supported the development and testing of nuclear weapons. A major component of these exposures resulted from releases of 131 I to the atmosphere. This paper addresses the public health implications of the combined exposures from the production of radioactive lanthanum at Oak Ridge which released 131 I, and 131 I deposited in the regions around Oak Ridge resulting from atmospheric weapons testing at the Nevada Test Site. Full application of uncertainty analysis is used to quantify estimates of thyroid dose, the excess lifetime risk of thyroid neoplasms, the risk of non-neoplastic disease at high exposures, and the probability that past exposure could be responsible for present thyroid disease. The results show that fallout 131 I is a substantial contributing factor to the total exposure and excess risk of thyroid cancer for those exposed as children residing downwind of local government installations. For many persons exposed in childhood, the upper confidence limit of the estimate of PC may exceed 50 %, regardless of the location where milk was produced.