EXAMINATION OF TESTICULAR-TUMORS IN THE BEAGLE DOG EXPOSED TO INHALEDPLUTONIUM

Gross and light microscopic features of testicular neoplasms were exam ined in the male beagle dog used in three studies to examine the life- span effects of inhaled plutonium (Pu). One hundred and sixty-six case s of testicular neoplasia (TN) occurred among 105 dogs that ranged in age from 7 . 5 to 17 . 7 years at the time of diagnosis. The 166 cases of TN comprised 113 interstitial cell tumours, 27 seminomas in situ, 19 seminomas, and seven Sertoli cell tumours. Serum testosterone and e stradiol 17-beta concentrations, and the serum testosterone-to-oestrad iol ratio were determined in 39 dogs with TN and in five clinically no rmal, sexually intact, age-matched cohorts. Serum hormone concentratio ns did not differ significantly among tumour types or between dogs wit h neoplasms and age-matched cohorts. There was a significant relations hip between initial lung deposition (ILD) of Pu and activity in the te stis (Bq/g testis). The slope of the relationship was 0 . 35, 0 . 89 a nd 0 . 91 for (PuO2)-Pu-239, (PuO2)-Pu-238 and Pu-239(NO3)(4) respecti vely. Pu in the testis at long times (> 5 years) after inhalation was between 0 . 0001 and 0 . 03% ILD, depending on the physicochemical for m of Pu. Although the mean activity of Pu in the testis of dogs was hi gher in those life-span studies employing (PuO2)-Pu-238 and Pu-239(NO3 )4, the cumulative proportion of dogs with tumours, the distribution o f tumour types, and mean time to first tumour was not significantly di fferent among the three studies or dose groups, including controls, wi thin a study.