Estimated risk to human bone from 239Pu

The cumulative risk in terms of average skeletal dose from 239Pu, was tentatively estimated on a linear model to be about 200 bone sarcomas/106 person . rad. This estimate predicts that about 200 cases of bone sarcoma may be induced during the lifetime of 1,000,000 persons each receiving one rad to the skeleton from 239Pu. The risk estimate is based on the observed incidence of bone sarcomas in German patients receiving long protracted irradiation from repeated injections of 3.62-day 224Ra, an α-emitter which like 239Pu decays to a large extent on bone surfaces. Independent support for this risk estimate comes from the fact that it exceeds the bone sarcoma risk from 1600-yr 226Ra in man by roughly the same factor as the risk from bone-surface seeking 239Pu exceeds that from bone-volume seeking 226Ra in experimental animals. The risk estimate is restricted to protracted irradiation from bone-surface seeking α-emitters, such as 224Ra, 239Pu, and 241Am at cumulative doses not to exceed a few thousand rad. It should not be used for the bone-volume seekers nor for the β-emitters. The risk estimate must be regarded as provisional and open to future revision