Reactor accidents

Some of the issues involved in the public health measures and the use of KI in a reactor accident have been reviewed. It is suggested that the widely applied risk estimates for induction of human thyroid cancer by radioiodine are probably too high since they are generally derived from x-radiation of children and since 131I seems less carcinogenic per gray than external radiation. The adult protective action guideline currently recommended by the FDA of 0.25 Gy (25 rad) for KI administration may be overly conservative. If KI is to be used, 1 Gy (100 rad) to the thyroid for adults and .50 Gy (50 rad) for children may be a more appropriate action level. For maximum effectiveness, KI must be taken immediately before or at the time of exposure, a requirement producing major distribution problems. The logistics of KI distribution are complex and seem to limit its use to special situations. Significant side effects can occur from iodide ingestion, although they are not likely to be frequent with the KI dose proposed. In most accident scenarios, the overall gain from KI use seems to be marginal. In considering KI use as public health measure, the authors are confronted with the problem of establishing sound public policy in the absence of sufficient scientific information and in the face of conflicting and often unrealistic perceptions. It is hoped that new and useful information can be obtained from the study of the effects of the Chernobyl accident where KI was used for a few days in the population in the immediate vicinity of the reactor