Comparative Effects of Iodine-132 and Iodine-131 in Rat Thyroid Glands

Abstract

The thyroidal effects of short-lived radioiodines such as 132I, 133I and 135I are not well defined. Upon release from nuclear reactors these radioiodines pose potential risk to human health. The effects of 132I and 131I were compared. The same effect was found in goitrogen-stimulated rat thyroid glands (in terms of 50% suppression of thyroid gland wt increase) at injected activities of 93 .mu.Ci 132I and 13 .mu.Ci 131I. Doses were 3 rad/.mu.Ci 132I and 194 rad/.mu.Ci 131I. The same 50% suppression for thyroid dose occurred at about 280 rad from 132I and 2500 rad from 131I, suggesting an approximately 9-fold increase in radiologic effectiveness of 132I over 131I.