Fumonisin B-1 carcinogenicity in a two-year feeding study using F344 rats and B6C3F(1) mice

Fumonisin B-1 (FB1) is a mycotoxin isolated from Fusarium fungi that contam inate crops worldwide. A previous study demonstrated that FB1 promoted pren eoplastic foci in initiated rats and induced hepatocellular carcinomas in E D IX rats at 50 parts per million (ppm), but fundamental dose-response data were not available to assist in setting regulatory guidelines for this myc otoxin. To provide this information, female and male F344/N/Nctr BR rats an d B6C3F(1)/Nctr BR; mice were fed for two years a powdered NIH-31 diet cont aining the following concentrations of FB1: female rats, 0, 5, 15, 50, and 100 ppm; male rats, 0, 5, 15, 50, and 150 ppm; female mice, 0, 5, 15, 50, a nd 80 ppm; male mice, 0, 5, 15, 80, and 150 ppm. FB1 was not tumorigenic in female F344 rats with doses as high as 100 ppm. Including FB, in the diets of male rats induced renal tubule adenomas and carcinomas in 0/48, 0/40, 9 /48, and 15/48 rats at 0, 5, 15, 50, and 150 ppm, respectively. Including u p to 150 ppm FB1 in the diet of male mice did not affect tumor incidence. H epatocellular adenomas and carcinomas were induced by FBI in the female mic e, occurring in 5/47, 3/48, 1/48, 19/47, and 39/45 female mice that consume d diets containing 0, 5, 15. 50, and 80 ppm FB1, respectively. This study d emonstrates that FB1 is a rodent carcinogen that induces renal tubule tumor s in male F344 rats and hepatic tumors in female B6C3F(1) mice.