oa \ cn ea eeeAT LSemegme na STE EA, ee ee case of thyroid cancer per 230 children; a minimum of one case in five thousand children. Not unless many more children in the Marshall Is- lands had been exposed to iodine 131 fallout would the absence of cancer or other thyroid abnormalities there suggest that cancer oer other thyroid abnormalities sould be unlikely in the Utah children. The comments from Dro Wolff of the Radiological Health Department of the, U.S, Public Health Service (p. 2) describe what is currently being done and what is planned in the search for pathological effects. The small expansion of the present field study in southern Utah and the collection and analysis of Utah and Nevada records of thyroid surgery are both useful steps. Whether “extensive epidemiologic studies” should be designed on the basis of Dr. Mays’ dosimetry is questioned by Dr. Wolff because the present field study is difficult and costly, with “no characteristic clinical Robert A. Conard Robert A. Conard is head of the Marshall Island Surveys at the Brookhaven National Laboratory. The studies of the Utah children proposed by Dr. Mays are worthy of consideration. However, the task of reconstructing the thyroid doses in this population due to fallout from detonation of different nuclear devices over the past years would appear to be extremely difficult, if not impossible. Also the logistics of institut- ag retrospective and prospective studies in this popula- tion of children are formidable. The diagnosis of radia- tion-induced thyroid lesions would be extremely difficult to separate from thyroiditis and other prevalent thyroid conditions in this population without careful pathologic and other studies. The Salt Lake City population of children is quite large for the thorough studies that would be necessary. Perhaps concentration of efforts on the more heavily exposed Washington County children would result in more meaningful information. In our studies in the Marshall Island people exposed — to fallout in 1954, twelve years ago, we have noted over the past few years the development of thyroid abnormaljties in fifteen of nineteen children exposed at less than ten years of age (thirteen with benign thyroid nodules and two with hypothyroidism).' One adult developed cancer of the thyroid. It should be pointed out that the incidence of thyroid disease is quite low in the Marshall Islands. Although dose estimates are not precise, it was calculated that the thyroid glands of the young Marshallese children received in the range of 700-1400 rads from radioiodines internally absorbed and in addition 175 rads from gamma radiation (similar to x-rays). These doses are considerably Scientist and Citizen’ 5012119 picture that can be reliably screened out of a ‘well’ population without recourse to intensive study.” The problem is certainly a unique, complex and difficult one, but it is of such importance that neither difficulty nor cost should be allowed to stand in the way of expanded and, if nécessary, intensive studics. Dr. Wolff docs not comment on the possibility of improving the dosimetry. If this could be done and small areas of high dosage identified, the intensive studies might first be concentrated in those arcas. In looking for thyroid damage within the “well” population, new and unorthodox methods may have to be tried; new screening procedures sought, If the questions now being asked are not yielcing the answers, other questions may have to be asked; other studies designed. This is a challenge, not only to the Public Health Service, but to all members of the scientific community. who have an interest in the problem and a competence in’ one of the related disciplines. higher than those received by the Utah children. More pertinent is the absence thus far of any thyroid abnormalities in 40 other Marshallese children, on a different island, exposed. inthe same age range, who received an estimated 55-125 rads to their thyroid glands, and also lack of thyroid abnormalities in six children, on still another island, that received an esti- mated 300-600 rads to their glands. These doses are probably also higher than those received by the Utah children. Therefore, based on the Marshallese experience, it does not seem likely that an easily detectable increase in thyroid abnormalities will be found in the Utah children. However, it should be pointed out that the numberof exposed Marshallese children is too small ‘to establish a low or threshold dose of induction of thyroid abnormalities. If thyroid dosimetry provessatisfactory and thyroid studies could beeffectively pursued in the Utah children, the data collected, even if of a negative nature, would be valuable. REFERENCE 1. R. A. Conard, J. E. Rall, and W. W. Sutow: Thyroid nodules as a late sequela of radioactive fallout in a Marshall Island population exposed in 1954. New England Journal ot Medicine 274: 1392-1399, June 23, 1966. Robert C. Pendleton Robert C. Pendleton is head of the Radiological Health Department of the University of Utah. Dr. Mays inas covered the problems relative to re- assessing the hazard to children in the Utah area admirably, and my comments will be concerned with the ecological factors that have to date not ocen taken