the term "action level'' is recommended. In general it will be appropriate to institute countermeasures only when their social cost and risk will be less than those resulting from the exposure. Setting of action levels is the responsibility of national authorities. It is not desirable to expos e members of the public to doses as high as those considered to be acceptable for radiation workers because children are involved, members of the public do not make the choice to be exposed, and members of the public are not subject to selection, supervision and monitoring, and are exposed to the risks of their own occupations. For planning purposes, dose limits for members of the public are seta factor of ten below those for radiation workers. The ICRP dose limits for individual members of the public are presented in Table II No maximum "somatically significant"' dose for a population is given. The genetic dose to the population should be kept to the minimum amount consistent with necessity and should not exceed 5 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. TABLE I ICRP DOSE Limits 1/ Individuals Population Gonads, red 0.5 rem/yr Skin, bone, 3.0 rems/yr 2/ Hands and forearms; feet and ankles 7.5 rems/yr - Cther single organs 1.5 rems/yr - bone-marrow thyroid Genetic dose 3/ - - 5 rems/30 yrs 1/ For conditions and qualifications see ICRP Publication 9. 2/ 1.5 rems/yr to thyroid of children up to 16 years of age. 3/ See paragraphs 84, 85, and 86, ICRP Publication 9. HI—-4