BASES FOR CALCULATION OF RISK ESTIMATES USED IN “THE MEANING OF RADIATION AT BIKINI ATOLL” I. ASSUMPTIONS Estimates of cancer and birth defect risks for the Bikini populations were based on a number of assumptions. sulted from consultation Some of these assumptions re- with other scientists including members of the BEIR committees. 1. Risk coefficients not been accepted from BEIR-I were used because BEIR-111 had by any U.S. government agency. We elected to use the values as given in BEIR-I rather than the revised values based on increased age of the population shown in Table V-4 of BEIR-111. i I 2. For estimates and the absolute risk. of cancer risk both the relative risk coefficient were used to give a range of estimated The absolute cancer incidence, which is not known for the Bikini population. 3. I The I 1 which is unknown for the Bikini it is probably less reliable than the estimates calculated risk coefficients. For estimating dose was used because increased cancer incidence, the bone marrow it was slightly higher than the whole body dose. This probably introduced 4. I gives a high value, but since it is based on cancer incidence, from the absolute , and is not dependent upon the spontaneous relative risk coefficient population, \ risk coefficient gives a lower value, is less vari- able with the population the spontaneous ,, I risk coefficient For estimating a small element of conservation. birth defects neither BEIR-I or BEIR-111 is very clear about what is meant by parental dose, thus it is not clear whether birth defects should be based on the dose to one parent or both parents. I I In the latter case, the 30-year whole body dose would be doubled. We assumed the BEIR-I risk of 0.2% rem was based on both parents being irradiated. Also because we believed the risk coefficient from BEIR-I ,