INGESTION OF NEVADA TEST SITE FALLOUT - INTERNAL DOSE ESTIMATES

This paper summarizes individual and collective dose estimates for the internal organs of hypothetical yet representative residents of selec ted communities that received measurable fallout from nuclear detonati ons at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated,vith over 20 radionuc lides, were estimated with use of the PATHWAY food-chain-transport mod el to provide estimates of central tendency and uncertainty. The thyro id gland received much higher doses than other internal organs and tis sues. In a very few cases, infants might have received thyroid doses i n excess of 1 Gy, depending on location, diet, and timing of fallout. I-131 was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (<3%) than those from ex ternal gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallo ut events; doses to more distantly located people were generally small er, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal or gan doses through ingestion varied dramatically with seasonal timing o f the test, with maximum dose per unit fallout occurring for early sum mer depositions when milk cows were on pasture and fresh, local vegeta bles were used. Within specific communities, internal doses differed b y age, sex, and lifestyle. Collective internal dose estimates for spec ific geographic areas are provided.