Notwithstanding the unattributability of stochastic effects, it should be noted that under present knowledge, it can be demonstrated that risks (rather than factual effects) can in fact be attributable to radiation exposure situations, even to those delivering small doses. Therefore, for reasons of radiation protection, and also of duty, responsibility, prudence and precau­tion, it is necessary to ascribe nominal radiation risks to prospective expo­sure situations. Thus, nominal risk coefficients should be developed from the observed increased incidence of radiation effects at high doses and be used solely for radiation protection purposes (see hereinafter).