Thorium isotopes in autopsy samples from thorium workers.

Concentrations of 232Th and activity ratios of 228Th to 232Th and 230Th to 232Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of 232Th activity concentrations (mBq per gram of wet tissue) were 0.17-94 in lungs, 3.

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).

Cancer risk from the lifetime intake of Ra and U isotopes.

From extensive human data on the induction of skeletal cancers (bone sarcomas and carcinomas of the head sinuses) by 226Ra, 228Ra and 224Ra, the cumulative lifetime risk to 1 million people, each ingesting 5 pCi of a Ra isotope per day, was calculated to be nine bone sarcomas plus 12 head carcinomas for 226Ra, 22 bone sarcomas for 228Ra, and 1.6 bone sarcomas for 224Ra. Assuming that the risk per rad of average skeletal dose is equal for 226Ra and the U isotopes with half-lives exceeding 1000 yr and that the equilibrium skeletal content is 25 times the daily ingestion of 226Ra, but 11 times the daily ingestion of long-lived U, the cumulative life-span risk to 1 million persons, each ingesting 5 pCi per day of 233U, 234U, 235U, 236U or 238U, is estimated to be about 1.

Mortality from cancers of major sites in female radium dial workers.

The female radium dial workers have now experienced significant mortality from cancers other than the bone sarcomas and head carcinomas long known to be radium induced. The relationships of radium exposure to mortality from cancers of the stomach, pancreas, colon, rectum, liver, lung, breast, cervix, and corpus uteri, and from leukemia were studied in 1,285 pre-1930 dial workers. Mortality was compared with that expected from rates for US white females, with and without adjustment for local area mortality rates, and with mortality in dial workers exposed from 1930 to 1949.