Radiation in the workplace: an opportunity for substantial epidemiological evidence

Studies of the long-term health experience of the Japanese survivors of the atomic bombings of Hiroshima and Nagasaki are highly impressive investigations of the late effects of exposure to ionizing radiation, which continue today and still contribute significant evidence some seven decades after the bombings (Ozasa et al. 2019). It is upon the cancer risk estimates derived from the LifeSpan Study (LSS) of a large cohort of atomic bomb survivors that the present system of radiological protection recommended by the International Commission on Radiological Protection is primarily (but not solely) based (ICRP 2007). Nonetheless, no single epidemiological study, however impressive, will provide a sufficient basis for the framework of radiological protection because there will be aspects of protection that will not be covered. For example, the Japanese atomic bomb survivors provide no direct evidence on the effects of alpha radiation, and this must be gleaned from other sources, such as the studies of underground hard-rock miners exposed to radon and its decay products. A further source of uncertainty is that the atomic bomb survivors are a Japanese population briefly exposed at a high dose-rate in the mid-twentieth century, which raises questions about applicability of risk estimates derived from the survivors to those chronically exposed to low dose-rates and who experience different background health risks, such as a twenty-first century population in North America. These questions point to the evidential value of studies of those exposed to radiation in the course of their employment.