DOSIMETRY AND PATHOLOGY OF NP-237 IN FEMALE RATS

Female Sprague-Dawley rats, 10-12-week old and weighing about 240 g, w ere injected intravenously with Np-237-nitrate. In the toxicological s tudy 77 rats served as controls and 28 rats per group received single doses of 5.2 and 26 kBq, respectively, per kg body weight. In addition , 12 rats of each injection level, sacrificed at defined points in tim e, were used for dosimetric studies. During the whole life-span the bo dy weight and Np-237 whole body-content of each animal were recorded. After death a detailed pathological examination was made of each anima l in the cronical study. One day after injection 48% of the injected a ctivity was in the skeleton, 9.3% in the liver, 3% in the kidneys and 4.4% in the rest of the organs. Whereas in all organs the activity dec reased very fast, the half-life in the skeleton was about 1400 days. T he bodyweights were comparable in the three groups, but the life sp an decreased from 800 days (control group) to 644 days after injection ( 26 kBq kg(-1) body weight group). The main lesions in the female rats were mammary tumors (73%) and pituitary gland tumors (52%). With incre asing activity the incidence of pituary gland tumors decreased and tha t of osteosarcomas increased from 1.3% (control group) to 32% (26 kBq kg(-1) body weight group), whereas the remaining lesions showed no inf luence on the activity.