' carcinogenic -)- by the Federal hadiation Council. On the assump- tion that the induction of cancer is prorortional to radiation exposure, an estimate of risk cin be made. Beach and Dolphin, of the United Kingdom atomic Energy Authority, considering ceveral sources of data, calculated that, on the average, 35 cases of thyroid cancer may be expected per million persons exposed to one rad of thyroid radiation. In terms relevant to the present testimony, i ia 285 children exposed to 100 rad thyroid radiation may develop thyroid cancer. By any standard, this is an unacceptable risk Estimates of radiation damuge are difficult, not only because of the uncertainties of some of the assumptions, but also because damage does not become evident for muny years after the exposure has taken piice. The average latent period vetween radiation and cancer of the thyroid approximates 10 years; in some instances, the latent period may extend to 20 years. If the thyroid radiation exposures near the Nevada Test Site are as righ as suggested in this testimony, careful medical follow-up of exposed populations might yield evidence of damage by this “sme 5) A survey of “he avatlable gamma and beta radiation measurements of ‘ailout resulting from 31 of the total of 99 tests conducted +1 Nevacs ir. the period 1952-58 shows that conditions which ‘inde. the circumstances stated above) lead to hazardous thyro.d exposures in children have occurred not only in areas neighboring the Nevada Test Site, but also in \