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This paper describes the history, organization, activities and recent scientific accomplishments of the United States Transuranium and Uranium Registries. Through voluntary donations of tissue obtained at autopsies, the Registries carry out studies of the concentration, distribution and biokinetics of plutonium in occupationally exposed persons. Findings from tissue analyses from more than 200 autopsies include the following: a greater proportion of the americium intake, as compared with plutonium, was found in the skeleton; the half-time of americium in liver is significantly shorter than that of plutonium; the concentration of actinide in the skeleton is inversely proportional to the calcium and ash content of the bone; only a small percentage of the total skeletal deposition of plutonium is found in the marrow, implying a smaller risk from irradiation of the marrow relative to the bone surfaces; estimates of plutonium body burden made from urinalysis typically exceed those made from autopsy data; pathologists were unable to discriminate between a group of uranium workers and persons without known occupational exposure on the basis of evaluation of microscopic kidney slides; the skeleton is an important long term depot for uranium, and that the fractional uptake by both skeleton and kidney may be greater than indicatedmore » by current models. These and other findings and current studies are discussed in depth.« less |
