131I Concentrations in Air, Milk and Antelope Thyroids in Southeastern Idaho

Abstract

Iodine-131 concentrations were determined in air, milk, and antelope (Antilocapra americana) thyroids from southeastern Idaho during 1972–77. Samples were collected in the vicinity of the Idaho National Engineering Laboratory Site which has 17 operating nuclear reactors, a fuel reprocessing plant, and a nuclear waste management facility. Samples were also collected from control areas. During the study, fallout occurred from five People's Republic of China above-ground nuclear weapon detonations. All 131I detected in air and milk samples was attributed to fallout from the Chinese nuclear tests. 131I was detected in low-volume air samples following only one of the five detonations while 131I was detected in milk following four of the detonations. 131I occurred in antelope thyroids during all five of the fallout periods and following at least one atmospheric release from facilities at the Idaho National Engineering Laboratory Site. Thyroids were the most sensitive indicators of 131I in the environment fo ved by milk and then air. Maximum concentrations in thyroids, milk, and air were 400, 20 and 4 times higher respectively than their respective detection limits.