THE DISTRIBUTION AND EXCRETION OF THORIUM SULPHATE’

The experiments described below were carried out as part of a series of experi-ments on the toxicity of thorium. A few distribution and excretion studies have been reported in the past (Hevesy and Wagner, 1930; Hamilton, 1947; Maxfield and Mortensen, 1941; Wolf, Gatsch and Born, 1944; Salerno and Mattis, 1951) with results which were frequently contradictory. In most of the experiments, a carrier-free radioactive isotope of thorium was used (ionium, UX1), which gave information concerning the metabolism of tracer amounts of thorium but not of the quantities employed in toxicity studies or in human exposures. Also, it was of importance to determine whether the metabolism of a soluble thorium com-pound would be similar to that of an insoluble one such as thorium dioxide, since there is considerable information concerning the insoluble compounds from the use of thorotrast as a radio opaque medium which is removed from the blood by the reticulo-endothelial system. METHODS. Since chemical determination of thorium in tissues is a difficult and not accurate procedure (Mattis, 1950), IJX, (,0Th234) was used as a radioactive tracer. The solu