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The effects of selenium (Na2SeO3) on aflatoxin B1 (AFB1)-induced hepatic neoplasia were studied in the rat. Putative preneoplastic foci and nodules composed of basophilic, eosinophilic, and clear cells developed early. Basophilic foci were seen first; in the later stages basophilic and eosinophilic nodules predominated. At each stage the AFB1 + Se groups showed fewer and smaller foci and nodules than the AFB1 - Se group. The number of foci in the AFB1 + 3 ppm Se group and their mean area were smaller than those in the 6 ppm Se + AFB1 group. At the end of the experiment hepatocellular carcinoma (HCC) was found in 11/18 rats (61%) of the AFB1 - Se group. HCC was not found in either of the groups given AFB1 + Se. We conclude that Se had an inhibitory effect on the initiation and promotion stages of AFB1-induced preneoplastic foci and nodules. Se also prevented progression of these nodules to HCC even after cessation of AFB1 administration. The inhibitory effect of Se at 3 ppm was greater than at 6 ppm. The 6 ppm Se group also showed evidence of toxicity.

The effect of Rhizopus delemar on the carcinogenicity in rats of Aflatoxin B1 was studied. The Aflatoxin B1 was administered in free drinks to each male wistar rat at 126 micrograms per week such that a total dose of 3.40 mg was given over a period of 27 weeks. The culture abstract of Rhizopus delemar was added simultaneously to a group of these rats by mixing the Aflatoxin B1 solution. Animals were killed separately during 18th, 30th, 38th and 52nd week. Liver cell altered foci and neoplasms were qualified by using light microscopic and electromicroscopic morphology, by the morphometry and by the enzymic reactions. In the group of Aflatoxin B1 the incidence of hepatocellular carcinoma was 71%. In the group receiving Rhizopus delemar together with Aflatoxin B1, the hyperplastic foci and pathological enzymic foci were decreased at all times pointed and atd at termination, and in none of the rats had liver neoplasms appeared. The result of this experiment showed that the Rhizopus delemar has intensive capacity in inhibiting the toxic damage and carcinogenicity of the liver by the Aflatoxin B1, because it is not only able to postpone the appearance of altered foci and to control their development but also to accelerate their withdraw in advance. The Rhizopus delemar can be used as a feasible and efficacious means to control the intoxication of Aflatoxin B1.