The wide margin of implicit built-in safety factors in current radiation protection standards

The lowest doses and dose rates at which radiation damage has been detected are summarized, and also the doses and dose rates for which no known effects could be demonstrated. The lack of relevant experimental data at low doses was the main justification for a linear extrapolation of the damage effects observed at relatively high doses back to low and near-zero doses and dose rates. Evidence is reviewed of non-linear dose-effect relationships that frequently fit available data. It is proposed that man-made radioactivity, of the magnitude of local variations in the natural background activity (a few tenths of mrems/yr), be treated as insignificant. It is misleading to treat as factual the numerical death estimates derived from radiation protection guides. There is no objective justification to reduce these standards of permissible exposure to man-made radiation to levels below those recommended by ICRP. (author)