THE DYNAMICS OF THE TRANSFER OF CESIUM-137 TO ANIMAL FODDER IN AREAS OF RUSSIA AFFECTED BY THE CHERNOBYL ACCIDENT AND DOSES RESULTING FROM THE CONSUMPTION OF MILK AND MILK-PRODUCTS

Data on the concentration of Cs-137 in animal fodder from collective f arms in Russia on which no countermeasures were applied following the Chernobyl accident have been evaluated for the period 1987 to 1994. Th e aggregated transfer factor (Bq.kg(-1) per Bq.m(-2)) was found to inc rease in the order fodder beet < maize < perennial grasses < natural g rasses and decreased with increasing clay content in the soil. Effecti ve half-lives for Cs-137 Of between 1 and 3 years have been calculated for the period up to 1989. From 1989 onwards the data are somewhat mo re variable and effective half-lives between 3 and 10 years are observ ed. Mean individual effective doses in 1987 from the consumption of mi lk and milk products produced from cattle fed on a typical diet of fod der crops produced on sandy soils are calculated as 3.1, 3.3 and 4.0 m u Sv per kBq.m(-2) for Russia, Belarus and the Ukraine respectively, w ith 95% confidence intervals for the three Republics jointly of 2.2 to 6.0 mu Sv per kBq.m(-2) The corresponding values are some three times higher for production on pear soils and about ten times lower in the case of clay soils.