Estimates of cancer risks from low-level exposure to ionizing radiation: the BEIR Report 1980

This paper summarizes the significant conclusions of the National Academy of Sciences 1980 report on the carcinogenic effects of low levels of ionizing radiation. The dearth of epidemiological data on the effects of doses in the range 1 to 20 rads make it necessary to assume a theoretical relation between radiation dose and the likelihood of cancer induction, so that predictions of low-dose effects can be made on the basis of relatively well-defined high-dose observations in man. The BEIR Committee has been guided by radiobiological data on cellular and animal effects and by the statistically weak data on human cancer induction by low doses, primarily the Japanese A-bomb survivor data, to derive an envelope of risk estimates based on three dose/effect relations. Employment of a linear-quadratic relation derived from cancer mortality of the survivors in the period of 1950-74 has provided the basis for the preferred set of risk estimates for whole-body exposure to low LET radiation. No allowance has been made for dose-rate effects. The best estimate of increased cancer mortality risk for 1 rad/year of whole-body low LET radiation received between ages 20 and 65 is about 2% of the normal expectation of death from cancer. The increase in the risk of cancer occurrence is similar. For estimating risks from partial body exposure to specific internal organs, the predominance of high-dose data has led to the adoption by default of a linear dose/effect relation except for leukemia and bone cancer. The continuing uncertainty regarding increased sensitivity of the fetus to the carcinogenic effects of radiation is noted. The report expresses skepticism regarding several recent claims of increased cancer in limited populations exposed to doses of the order of 1 rad