Aflatoxin B 1 , a hepatocarcinogen in the infant mouse.

Abstract

Summary Aflatoxin B1 has been administered to newborn and infant C57BL × C3H F1 mice for a further evaluation of its hepatocarcinogenicity in this species. To date, adult animals have been shown to be relatively refractory. One-, 4-, or 7-day-old groups of animals were exposed to either single or limited numbers of i.p. injections of aflatoxin B1. Animals selected at random were sacrificed at 52 and 82 weeks of age. Newborn animals appeared to be more prone to the lethal effect of aflatoxin B1 than did the 4- or 7-day-old infants. Male infants developed hepatomas by 52 weeks of age. At 82 weeks, both tumor incidence and tumor mass increased in all male groups. Seven-day-old treated females developed hepatomas, although at a low incidence rate. Thus, it has been demonstrated that aflatoxin B1 is a potent hepatocarcinogen under the experimental conditions. It has been concluded that the infant age and the male hormonal environment were factors favorable for the inception and expression of liver neoplasia in mice.