Metabolism of radio-ruthenium in the rat; consideration of permissible exposure limits.

Abstract

The metabolism of ruthenium in the rat was studied in experiments involving the acute and chronic adimistration of Ru/sup 106/ by vnrious routes. Gastrointestinal absorption amounts to about 3 per cent of ruthenum fed as solutions in the pH range from 1 to 4, and is little affected by the chemical state or previous history of the solutions or by the concentration of ruthenium. The highest concentration of ruthenium, even after prolonged chronic feeding, is present in the kidney. Bone and gonads also accumulate sufficient concentrations of rutheniu pi u to make them of comparable hazard concern to the kidney. Because of uncertainties inherent in the extrapolation of the rat data to man, an unequivocal choice of critical organ among these three possibilities cannot be made. Based on a permissible dose to the critical organ of 0.3 rem/week, the maximum permissible concentration for Ru/sup 106/ in water is calculated to be 4 x 10/sup -3/ mu c/ml. This would be approximately correct on the assumption of either kidney, bone, or gonads as critical organ. Limiting irradiation of the gastrointestinal tract itseif to 0.3 rem/week results in more » a lower maximum permissible concentration of 1 x 10/sup -4/ mu c/ml. Applying a genetic limit of 10 r to the gonads during the first thirty years of life results in a maximum permissible concentration of 5 x 10/sup -5/ mu c/ml. (auth) « less