Marshallese) (138-141). These two individuals exposed in utero described here appear to be the. first known cases developing thyroid nodules after radioiodine exposure. 4. Problems Associated With the Thyroid Hormone Treatment Program In 1965 a BNL thyroid advisory panel recommended that the exposed Rongelap people be placed on thyroid hormone treatment for life as a prophylactic measure to reduce the risk of further thyroid nodule development (by sup- pression of TSH levels) and possibly enhance growth and development in some of the children in whom this was retarded.* Since that time, the exposed Rongelap people have been receiving daily (or weekly) treatment with synthetic L-thyroxine (Synthroid, Flint Drug Co.). The Ailingnae people were also placed on the hormone treatment regimen in 1969 because of the development of thyroid nodules in that group. In the exposed Utirik population and in the unexposed groups, hormone treatment has been used only in those who have had thyroid surgery and, in some cases, to test the response of thyroid nodules to a trial treatment with the hormone. The Synthroid doses used usually have been 0.3 mg/day for people <50 years of age and 0.2 mg/day for those >50. However, the dosage has been adjusted downward in some elderly people and in a few people who showed symptoms on the dose given. As pointed out in past reports, there have been problems of maintaining a strict hormone treatment regimen in all of the people. Most of the people take the medication faithfully, but a number of them have been careless in Maintaining the regularity of treatment in spite of continued efforts by the medical team and the resident physician and his aides to impress upon them the importance of the treatment program. Omission of medication has been particularly serious in patients who had undergone thyroid surgery. A number of these have from time to time shown elevated serum TSH levels and a few questionable signs of hypothyroidism. Fortunately, except in one case (described below), treatment was resumed before serious consequences developed. In spite of all efforts, some post-operative patients still become lax at times about regularity of medication, as indicated by elevated serum TSH levels. As discussed previously (see Section IX.A.), two Rongelap boys exposed at one year of age received larger doses to the thyroid (perhaps >2000 or more rads) and developed hypothyroidism with stunted growth associated with atrophy of the thyroid gland. Ome of these responded satisfactorily to treatment with hormone, showing enhanced growth and development and no clinical evidence of hypothyroidism in spite of occasional elevations of serum TSH levels. The other case, however, though he had responded to the treatment with improved growth status, has become a serious problem with regard to maintaining thyroid treatment. On a number of occasions, he has exhibited periods of apathy, de- velopment of behavioral problems along with some degree of mental retardation, and refusal of food at times. This was associated with high levels of TSH. He has been hospitalized on several occasions with severe hypothyroidism. The above findings indicate the importance of maintaining a strict treatment *The rationale for such treatment has been supported by the finding that development of thyroid tumors in experimental animals hypophysectomy (142). -75- is completely prevented by