Absorption, retention and tissue distribution of radiocaesium in reindeer: effects of diet and radiocaesium source.

Radiocaesium absorption and retention in reindeer (Rangifer tarandus) calves was compared in groups fed diets containing different proportions of lichen and concentrates, and different chemical forms of radiocaesium ((134)CsCl in solution or fallout from the Chernobyl accident). Daily intakes of fallout radiocaesium were 15-23 kBq, while daily intakes of (134)CsCl ranged from 70 kBq to 1,160 kBq. The half-life for radiocaesium in red blood cells (RBC) in animals fed with a pure lichen diet exceeded that in animals fed with a combined diet of lichen and concentrates by 40% (17.8+/-0.7 days vs. 12.7+/-0.4 days). Corresponding differences in the half-lives for urinary and faecal excretion were about 60% and 40%, respectively. Transfer coefficients (F(f)) to reindeer meat were estimated to be 0.25+/-0.01 days kg(-1) for fallout radiocaesium and 1.04+/-0.03 days kg(-1) for (134)CsCl, reflecting differences in both radiocaesium bioavailability and retention. The bioavailability of the Chernobyl radiocaesium in lichen in 1988 was estimated at ca. 35% compared to (134)CsCl.