MAMMARY CARCINOGENICITY IN FEMALE CD RATS OF A DIOL EPOXIDE METABOLITE OF FLUORANTHENE, A COMMONLY OCCURRING ENVIRONMENTAL-POLLUTANT

We examined the mammary carcinogenicity in CD rats of droxy-1,10b-epox y-10b,1,2,3-tetrahydrofluoranthene (FDE), a genotoxic metabolite of th e environmental pollutant fluoranthene, FDE (2 mu mol or 10 mu mol) in 0.1 ml dimethyl sulfoxide (DMSO) was injected beneath each of the thr ee left thoracic nipples of groups of 20 rats each, with 0.1 ml DMSO a lone being injected under the right nipples. On the next day, the proc edure was repeated for the three inguinal nipples on each side. y-1,2- epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene (BcPDE, 2 mu mol per nipp le) was used as a positive control and DMSO alone as a negative contro l. Tumor development was assessed weekly by palpation and the experime nt was terminated after 41 weeks. Eighty five percent of the rats in e ach of the FDE treated groups developed histologically confirmed mamma ry tumors, compared to 11% in the DMSO treated animals (P < 0.01), Mos t tumors were on the left side. The lower dose of FDE induced a signif icant number of adenomas while the higher dose induced significant inc idences of both adenomas and adenocarcinomas compared to controls. BcP DE was a powerful mammary carcinogen, confirming our previous observat ion. The results of this study demonstrate the carcinogenicity of FDE to the CD rat mammary gland, Since FDE is a potentially transportable human metabolite of fluoranthene, its possible role as an etiologic fa ctor in breast cancer deserves further study.