Radiation and man

The radiation doses received by man from natural sources are considered with especial reference to those which arise from normal building materials. Considering dose/effect relationships, the concept of a dose threshold for such risks is examined. It is concluded that it is not meaningful to give dose limits for natural radiation but that there is no reason to exempt natural radiation from cost-benefit assessments as far as countermeasures are concerned. In addition any practice that results in radiation exposures should be subject to a risk-benefit assessment. Other exposures to which man is commonly exposed, especially x-rays for diagnosis, are considered in the light of such risk-benefit analysis. Finally risk-benefit assessments and their replacement by agreed dose limits for the protection of workers in certain areas such as radiology and uranium mining are considered. It is shown that radiation sources differ widely with regard to dose commitment and harm commitments. (U.K.)