Modifying effects of health status, physiological, and dosimetric factors on extrapulmonary organ distribution and excretion of inhaled plutonium in workers at the Mayak Production Association.

This paper summarizes the systemic organ distribution of plutonium in workers exposed by chronic inhalation at the Mayak Production Association (MPA). Using results of radiochemical measurements in soft tissue and bone samples collected at autopsy of 853 autopsy cases, this paper provides data on the effects of various chronic diseases and malignant tumors as well as exposure time, age, sex, and body burden on systemic retention of plutonium in 22 extrapulmonary organs and on the urinary excretion rate of the nuclide. Some aspects of this work have been reported already. The results of present autopsy studies showed that liver pathology accompanied by strong fatty dystrophy of hepatocytes results in a significant relative decrease in the fraction of systemic plutonium in the liver and contravariant increase in the skeletal fraction. The average fractions of systemic plutonium in the liver and the skeleton of those MPA workers were 15% and 75%, respectively, in comparison with 47% and 45% in healthy individuals. Some of the plutonium also redistributed from the liver via blood to other systemic soft tissues. Plutonium not redistributed was excreted with urine. The results of multivariate regression analysis indicated some time-related and sex-related changes not connected with pathology for the liver and the skeleton retention fractions and excretion rate of plutonium. The current ICRP biokinetic models do not account for the influence of different pathological processes in the body on plutonium distribution in systemic organs and urinary excretion. This could have significant consequences for dosimetry calculations and risk estimations.