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Thyroid hypofunction appearing as a delayed manifestation of accidental exposure to radioactive fallout in a Marshallese population

Conference ·
OSTI ID:7286909

The increased incidence of thyroid nodularity and carcinoma appearing as a late effect after exposure of the human thyroid to ionizing radiation is well-recognized. Despite the high prevalence of thyroid nodularity in Marshallese inadvertently exposed to fallout in 1954, only two subjects, both about one year of age at exposure, have been found to have primary hypothyroidism. The recent availability of sophisticated immunoassay techniques for thyroxine (T/sub 4/) and thyrotropin (TSH) has allowed more thorough thyroid evaluation of the exposed population who do not have known thyroid abnormalities (43 Rongelap people). Four of 43 Rongelapese had abnormally high basal TSH and TRH-induced TSH release on two such tests as opposed to only 2 of 214 controls. Plasma T/sub 4/ concentrations were low, or low-normal in these individuals. These results indicate the presence of early thyroid dysfunction. Several other subjects have shown at least one abnormal finding but have not had the required number of tests to meet the established criteria. In /sup 3///sub 4/ of these subjects the estimated thyroid exposure dose was less than 400 rads. Hypothyroidism has been previously noted after therapeutic doses of /sup 131/I for hyperthyroidism, but not in individuals exposed to the relatively low levels of thyroidal radiation (less than 400 rads) estimated for these individuals.

Research Organization:
Brookhaven National Lab., Upton, N.Y. (USA)
DOE Contract Number:
EY-76-C-02-0016
OSTI ID:
7286909
Report Number(s):
BNL-24104; CONF-780306-5; IAEA-SM-224/607
Country of Publication:
United States
Language:
English