Plutonium and other transuranics in small vertebrates: a review

The published data relevant to transuranics in small vertebrates inhabiting terrestrial environments is reviewed. Experimental results indicate that atomic size and valence state affect rates of absorption, transportation, and excretion of transuranics in living systems. Whereas there is a marked tendency for transuranics to hydrolyze to insoluble colloidal products at physiological pH, complexing agents and chelation enhance solubility and transportability. The natural modes of uptake of transuranics by vertebrates include absorption from the gut, the intact or damaged skin, and inhalation. Absorption from the gut into the bloodstream is very low. Potential hazards may exist if complexing or chelating agents are present, if absorption is continuous, or if exposure involves young animals. The intact skin provides an effective barrier to absorption of transuranics. Relatively high levels of absorption may occur when transuranics are administered subcutaneously or intramuscularly, particularly with increased acidity and solubility of the compounds. Inhalation is probably the most hazardous natural route of uptake. Insoluble transuranic compounds are retained in the lung and soluble compounds are transported rapidly via the blood to bone, liver, and other organs. Deposition of plutonium in mammalian gonads resulting in a decrease in spermatogenesis, ovarian damage, and reduced fecundity is documented. The current knowledge of the behavior of transuranics in terrestrial environments is limited. Plutonium and americium uptake by small mammals has been documented. Plutonium body burdens were related to depressed leukocyte count on a statistical basis. Reduced rodent populations in areas of high plutonium concentrations illustrate the problems of evaluating uptake by mobile animals