2. Birth Defects Risks Table 3 gives the calculations for the estimates of birth defects. B. Risk Estimates Based on BEIR-III Table 4 gives risk estimates based on BEIR-III risk coefficients. These were calculated for comparison purposesconly and were not used in the Bikini book. The highest estimates -for cancer risk result from using the linear relative risk model and are about the same as those given in Table 2 for the relative risk model. The lowest estimates result from the linear-quadratic absolute risk model-and are slightly less than those for the absolute model in Table 2. Thus, as far as estimates of cancer risk are concerned, those obtained using risk coefficients from BEIR-1 are in the same general range as those obtained using risk coefficients from BEIR-III. Risk estimates for birth defects obtained using the risk factor from BEIR-I gives values about three times those obtained using the upper value of the range of risk factors given in BEIR-III. If BEIR-III risk factors for birth defects represent a more enlightened assessment of this potential consequence of radiation exposure than the factor taken from BEIR-I for overall health defects, then the estimates in the Bikini book may be conservative by a factor of three.