C -6- : rems in 30 years from all sources other than natural background and medical procedures. No single type of population exposure should take up a disproportionate share of the total of the recommended dose limit. For exposures from uncontrolled sources, e.g., following an accident, ICRP identifies the term "action levels." The setting of action levels for particular circumstances is considered to be the responsibility of national authorities. BIBLIOGRA PHY