Studies of long term administration of aflatoxin to rats as a natural food contaminant

The effect of feeding aflatoxin, as a natural food contaminant, to rats over long periods of time was studied using multigeneration and longevity tests. The test animals in the multigeneration study consisted of three groups of rats fed diets containing 0, 1 and 10 ppb of aflatoxin (predominantly B₁) continued over four generations, with animals of the first and fourth generation fed the diets for 104 weeks. These diets were in proper nutritional balance and included 35% ground roasted peanut products; the ration with 0 ppb aflatoxin excluded the peanuts usually discarded; the one with 1 ppb had the roasted discards returned, while the ration with 10 ppb included the discards in amount 10 times that which had been initially removed. Another longevity study was also performed in which rats were fed diets containing aflatoxin at a level of 80 ppb. In this case, the test peanuts, also fed as a simulated peanut butter at 35% concentration, consisted entirely of roasted peanut discards. Control diets provided no peanut components. Animals fed the low levels of aflatoxin grew as well and actually had a higher percentage survival at 104 weeks than did the animals on the control, aflatoxinfree diets. Organ weights, liver total lipid and cholesterol levels were comparable in all groups. Pathological abnormalities, e.g., hemorrhagic and opaque spots and mottling in some of the livers, were attributed to the aging process since the abnormalities appeared in the control as well as the experimental groups. In the animals fed the aflatoxin at 80 ppb, which has been reported by several investigators to produce well-defined hepatomas in rats, there was liver involvement and some biochemical changes occurred that were not noted in the controls. However, no hepatomas were observed in these animals even after 21 months on this diet. The liver lesions, indicative of a toxic effect, have not been associated with the development of hepatomas. It is possible that some components of the diet used in these experiments may have protected the animal against hepatoma formation. Our studies indicate that there may be a tolerance for aflatoxin as judged by results in one species of rats when whole ground roasted peanuts provide the natural contaminant. Presented in part at the AOCS Meeting, New York, October 1968.