Abstract
Rats were exposed by inhalation to aerosols contaminated with 131I or intravenously injected with solutions containing 131I, resulting in initial body burdens of 20 to 1200 µCi/kg body weight. Whole-body counting, excreta and tissue analyses, and pathological examinations were performed to evaluate retention differences or tissue changes due to route of administration or to initial 131I body burden. Fifty to sixty percent of initially deposited 131I was excreted during the first 24 hours after both modes of administration. With the exception of thyroid gland and pelt, all organs examined decreased in 131I content the first day after inhalation exposure. Thyroid radioiodine increased during the first day to at least 3.2% of the initial body burden. Both transient and permanent changes, which were dependent on the initial quantity of 131I received, were observed histologically in the thyroid gland. Some latent changes were also noted in the pituitary gland.