Comments on "Updated analyses of combined mortality data for workers at the Hanford site, Oak Ridge National Laboratory, and Rocky Flats Weapons Plant" (Radiat. res. 136, 408-421, 1993)

ized that as early as 1981 (2) we had estimated that the cancers initiated by radiation exposure at Hanford typically caused death 25 years after the exposure, and that there was a significant increase of cancer effect with increasing age, such that exposures before 47 years of age had less than a tenth of the effect of exposures at 65 years of age. Thus, by our reckoning, most of the radiogenic cancers of Hanford workers would have been caused by radiation exposure between 47 and 65 years of age and (in consequence of a typical latency of 25 years) been included among deaths after 72 years of age (47 + 25). This estimate is to be compared with the finding of Gilbert et al. for cancer deaths after 75 years of age. More recently, we have reported the results of calculating minimum latency and minimum exposure age for radiogenic cancers of all types (3). These gave the minimum lat ncy (or lag) as 17 years, and the minimum exposure age (for any subsequent cancer effect) as 58 or 62 years. So once again the radiogenic cancers w uld be concentrated among deaths after 75 years of age. Our minimum death age for radiogenic cancers, which agrees so closely with the estimate of Gilbert et al., was obtained by having a critical exposure age below which there were no cancer effects. Exposures below this age were included in Table X of Gilbert et al., but if they had been excluded (thus greatly reducing their average doses), the trend statistics would have be n appreciably higher than the ones actually r corded. How much higher can be seen in Table I, which is based on Hanford data and shows the effects