Organ distribution of thorium in thorium workers: good agreement with new models of the International Commission on Radiological Protection.

Higher than environmental levels of (232)Th have been found in autopsy samples of lungs and other organs from four former employees of a thorium refinery. Working periods of the subjects ranged from 3 to 24 years, and times from end of work to death ranged from 6 to 31 years. Examination of the distribution of thorium among the organs showed that concentrations in the lung relative to pulmonary lymph nodes, bone or liver were much higher calculated from the dosimetric models in Publication 30 of the International Commission on Radiological Protection (ICRP). Much better agreement was found with more recently proposed models in Publications 68 and 69 of the ICRP. Radiation doses estimated from the amounts of thorium in the autopsy samples were compatible with health studies that found no significant difference in mortality from that of the general population of men in the U.S.