AM-241-INDUCED THYROID LESIONS IN THE BEAGLE

One of the features of Am-241 metabolism in the beagle dog is a relati vely high selective deposition in the thyroid glands, equal to approxi mately 0.06% of the injected dosage per gram. Retention is prolonged a nd principally in the interstitial connective tissue. The resulting av erage dose to the thyroid glands is about 1.42 and 0.76 times that del ivered to the skeleton and the liver, respectively. This thyroid dose is much higher than has been reported in people. Although significant morphological changes and reductions in serum thyroxine occurred in th is experiment, a significant increase in thyroid neoplasia was not obs erved.