[en] Risk estimates are based on epidemiological data and are subject to many uncertainties including the current uncertainty in the dosimetry of the Japanese survivors. However, risk estimates from other sources, excluding the Japanese data, do not lead to greatly different values. Furthermore, risk estimates made over more than a decade by various scientific bodies have differed little. Presumably these estimates represent a good basis for the quantitation of human experience following exposure to ionizing radiation. In considering risk in relation to protection levels the committed risk due to a single or continuous exposure varies in time and accumulates over the entire period of risk. Radiation risks are compared with other occupational and public hazards. The risks associated with current occupational, public and emergency levels and levels for use in space are discussed in relation to other hazards. Current average exposure levels for occupational circumstances do not seem unreasonable but radon exposures for some members of the public may constitute a more important source of exposure