Radiation protection biology then and now.

Purpose: Radiation biology is a branch of the radiation research field which focuses on studying radiation effects in cells and organisms. Radiation can be used in biological investigations for two, mutually non-exclusive reasons: (1) to study biological processes by perturbing their functioning (qualitative approach) and (2) to assess consequences of radiation-induced damage (quantitative approach). While the former approach has a basic research character, the latter has an applied character that is driven by needs of medical applications and radiological protection. Radiation protection biology is defined in the sense of the second approach. The aim of the article is to provide a historical review of how radiation protection biology developed and how it influences radiological protection. Conclusions: While radiobiological investigations started immediately after the discovery of X-rays, the qualitative approach dominated until the end of World War II. After 1945, the nuclear weapons race and nuclear energy programs initiated quantitative radiobiological research. Radiation protection biology does not provide results from which radiation risks can be directly derived. Rather, it provides data that is necessary for understanding the nature of risks. Most recent years have seen, especially in Europe, a growing interest in coordinated studies on the effects of low radiation doses.