Thyroid Abnormalities in a Marshallese Population Exposed to Radioactive Fallout in 1954

Page 1

13ROOK HAVEN NATIONAL LABORATORY ASSOCIATED UNIVERSITIES. INC . TEL. AREA CODE 516 YAPHANK 4-6262 Division of Biology The five Marshallese cases arrived at Brookhaven the latter part of May and were given extensive thyroid examinations. It was decided that surgery was indicated, and all five cases were transferred to the New England Deaconess Hospital in Boston, where Dr. Bentley P. Colcock of Lahey Clinic carried out thyroid surgery, removing the nodules in all cases. The pathological report on the surgical tissues was done by Dr. William A. Meissner at the New England Deaconess Hospital, and his report indicated that all nodules were benign and of the adenomatoid goiter type, except that one case had a small Hurthle’s cell adenoma which was also benign. Recovery from surgery was uneventful, and the five Marshallese were returned to the MarshaLl Islands, arriving around July 20. Enclosed is a hospital summary on each case, which will give the findings in more detail.

Page 2

TMYROID ABNORMALITIES IN A MARSHALLESE POPULATION During the past three years the development of thyroid nodules and hypothyroidism has been noted in a number of Marshallese people of Rongelap Island in the Pacific who had been exposed to radioactive fallout 12 years ago in 1954. This development is believed to be a law effect of irradiation of the thyrmicl Kland from internal :Ibsorptit}nof r:l(lioiodinesand external gamma radiation at the time of the fallo[lt. ‘Cl~crewere 64 people (54 IIOW living) who received a whole body dose of gamma radiation of 175 rads, extensive direct irradiation of the skin from deposition of fallout thereon and internal absorption of radionuclidcs in the fallout. Eighteen other During the 2-day period following the accident before the evacuation of the people occurred, the inhabitants absorbed radionucLides in the fallout by inhalation and ingestion of contaminated food and drinking water, Based on radiochemical analyses of pooled ~lrine samples taken several weeks after the Taken into consideration in those calculations were the time and length of the fallout period, the isotope energies of the various iodine nuclides, and the yield of the isotopes. Extrapolation to thyroid doses that the smaller thyroid glands of the young children received was”in the range of 700-1400 rads in the more heavily exposed group. Though “beta burns” were prevalent in the neck

Page 3

In 1963, 9 years after exposure to fallout, Ehe first thyroid nodule was detected in a 12 year old.girl in the more heavily exposed ‘group. Subsequently there have been increasing n~lmbers detected. In 1964, 2 further hypothyroidism in two boys WI1O had silown growth retardation. In September, 1965, 5 further cases were detected and this past March five more cases were found. This makes a total now of 16 cases with nodules plus two cases of hypothyroidism. Only one nfidule has been found to be malignant. Table I summarizes the incidence than 10 years of a~c with thyroid ahnorma[i.ties, in comparison witil no I:hyroi(i pathology noted in children of the same age range of the nonexposed population or in the lesser exposed populations. The incidence in those exposed at a greater age is considerably lower and not m[lch hi~hcr than that seen for the that is, greater than 50 years of age. Thyroid surgery has been performed on 11 cases with nodules, Ten of these cases, 9 children ( and one ‘adult) were all found to have benign noclules and one 41 year old woman had cancer. Four other children in the exposed gro[lp will have ti}eir thyroid nodllles recvalllntcd in Scptcmhcr 1966. A thyroid nodule iq onc adult male disappeared while on hormone therapy. ‘>; In most cases the thyroid glands contained multiple nodules ranging in diameter from a few millimeters to a few centimeters. All were nontender, some firm, others cystic, and sometimes even hemorrhagic. No lyrnphadenopathy was noted. The microscopic sections of the benign lesions showed quite bizzare appearance with a wide variety of differ8nt sized follicles, some small and “

Page 4

an aborrheal appearance. These changes rcscmblc those sceu in iodine de[icicncy (adenomatoid goiter). The one case of cancer of the thyroid occurred year old woman and was of the mixed papillary and follicular type.~ hypothyroid etiology for xrowth retardation noted in children in the group is strongly suggested by ti)e recent findings of definite hypothyroidism in two of the most retarded boys who had atrophic glands but no nodules. Their protein bound iodine levels have dropped below 2 IQ%. Two other children with thyroid nodules showed low values also. incomplete, it appears that the two boys showing most growth retardation have had a spurt in growth during the past 6 months on this therapy. It is too soon yet to evaluate the beneficial effects of this therapy in reducing the incidence of nodules of the thyroid gland. The radiation etiology of tl~csc tl]yroid lesions appears to be reasonably substantial dose of radiation from radioiodines and external gamma radiation. (2) Only a few older people in the unexposed or low exposure groups have shown any nodules of the there are no known well documented in tumors in children thyroid gland. (3) The diet is not lacking in iodine and goitrogenic foods. (4) Furthermore, the correlation of with later clcvelopmcnt of thyroid abnormalities has been animal and clinical st(dics. The development of thyroid whose thymic regions or neck were exposed during infancy is now well substantiated. Adenomatous lesions of the thyroid in children have also been reported 5 to 11 years after treatment with I131 for thyrotoxicosis. Though the dose range in the Marshallese is similar to those

Page 5

dose among the exposed people must have been marked. A reevaluation of the thyroid doses will be undertaken in the near future based on more precise information regarding urinary iodine excretion in the Marshallese. As a result of the present findings, it will he necessary to revise upwards che seriousness of tile internal hazard associated with fal Io(lt. Secondly, it has become increasingly evident that late of the thyroid gland, (neoplasias, hypothyroidism) are ~ than had been previously supposed. The high incidence effects of radiation much more common sequelae of thyroid lesions in ! the Marshallese emphasizes the caution with which radiation must be used clinically,, Chief, Marshall Island Medical Surveys Medical Research Center Brookhaven National Laboratory