Effect of ammoniation on the carcinogenicity of aflatoxin-contaminated groundnut oil cakes: long-term feeding study in the rat.

The efficacy of detoxication by ammoniation of aflatoxin-contaminated groundnut oil cakes was determined in long-term (18 months) feeding experiments with rats. The aflatoxin content of the cake was reduced very considerably by the pressurized application of ammonia, dropping from 1000 to 140 ppb at a gas pressure of 2 bar and to 60 ppb at 3 bar. No reversion was noted during the experiment. The percentage of hepatic tumours obtained was very high for the untreated cakes, but fell sharply with medium treatment and was reduced to zero by the treatment at 3 bar. A satisfactory dose-effect relationship was shown between the residual aflatoxin content of the cakes and the observed incidence of tumours. The results show that ammonia treatment is a practical solution to the problem of the carcinogenic potency of contaminated oil cakes.