Retrospective estimation of Plutonium-239 doses from transfer to the fetus for Mayak PA workers.

Purpose: The estimation of plutonium fetal transfer and the calculation of individual in utero and postnatal doses for the Mayak Production Association (PA) offspring cohort.

Materials And Methods: The model developed by the International Commission on Radiological Protection (ICRP) for the transfer of plutonium to the fetus following maternal intakes before and during pregnancy has been adjusted for application to analysis of the fetal transfer of (239)Pu for Mayak workers. Improved estimates of fetal to maternal concentration ratios (CF:CM) have been obtained based on a correlation observed between adult offsprings' measured daily urine (239)Pu activity and estimates of their mothers' systemic activity at conception. Data on (239)Pu activity in daily urine samples were collected from 13 selected adults whose mothers worked at the Mayak PA facility during the period from 1948-1953, before and/or during pregnancy.

Results: A comparison of measured and modeled excretion data enabled a mean value of 0.18 ± 0.02 (n = 21) to be inferred for the Pu CF:CM ratio, with a coefficient of variation of 60%.

Conclusions: Point estimates of the individual in utero and postnatal absorbed doses for the red bone marrow and liver were in the range 2…13 mGy in 95% of the cases for the cohort of 1936 offspring.