Quantitative Plutonium Microdistribution in Bone Tissue of Vertebra From a Mayak Worker

Abstract

The purpose was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, quantitative relationship of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in human as well as other cases with different exposure patterns and types of plutonium.

Bone as Target Organ for Metals: The Case of f-Elements

“…This model has further compartments specifically assigned to two forms of bone surfaces: quiescent and forming. Interestingly, microdistribution studies of plutonium in the vertebra of a nuclear fuel cycle plant (Mayak) worker were recently performed and suggest further developments to possibly improve the ICRP 67 model . They revealed an underestimation of the migration of plutonium into the bone volume and an increase in the global plutonium burden, possibly attributable to liver deficiency shortly before death.…”