The transfer of 239/240Pu to cow milk

Abstract

In summer 1993 we measured the transfer of 239/240Pu to milk from herbage from a pasture located 5 km from the Chernobyl nuclear power plant. In one treatment cows were allowed to graze freely on the pasture. In a second treatment, cows were fed herbage collected from the pasture in stalls. The milk transfer coefficient; F m did not vary significantly between treatments and the mean value of 7.5 × 10 −6 d l −1 was higher than previously reported values. Despite many values of F m for Pu in the literature we identified few relevant original data sets. Transfer coefficient values for Pu are only appropriate when used in conjunction with a specified time period or an appropriate model which allows for the biological half-life. We recommend for screening purposes an F m value of 1 × 10 −5 d l −1 for Pu, with an order of magnitude lower value being appropriate for cows which are only exposed for one grazing season.