Aflatoxin, cancer associated with

Liver tumors have been directly attributed to exposure to some toxicants. Androgens (associated with male sex hormones), aflatoxins (from fungi, see Chapter 19), arsenic, and thorium dioxide (administered as a suspension to many patients between 1920 and 1950 as a radioactive contrast agent for diagnostic purposes) are known to cause liver cancer. 

There is little in the literature relative to vitamin A and colon cancer in human populations. Experimental animal studies, however, strongly suggest that vitamin A deficiency may have a role in this type of cancer. We have shown that a deficiency of vitamin A increased DMH-induced tumors and shortened the lag time for induction, compared to normally supplemented controls (72). More recently (73) we have confirmed a protective role for vitamin A in colon carcinogenesis (Table XVII). Furthermore, we have shown (74) that vitamin A deficiency can result in colon tumors in rats given aflatoxin (AFB ) which is normally a liver carcinogen (Table XVIII). The colon tumors associated with the hepatocarcinogen AFB.. appear to be a result of differences in metabolism and binding of AFB or its metabolite ) to colon DNA under conditions of vitamin A deficiency (75). 

One excellent food that illustrates this dichotomy is the peanut. First, there is a well-documented physical hazard associated with children who choke on them. Should we label peanuts to protect us from these acute hazards, which probably killed more children than exposure to any trace level of pesticide on the same peanut Secondly, some individuals are acutely allergic to peanuts or any food containing them. This is a serious problem for those sensitive individuals, and efforts continue to be made to label foods containing peanuts to alert these individuals. The main toxicological problem of peanuts and products made from them, such as my personal dietary staple, peanut butter, is the problem of contamination with molds. Aflatoxin, found in moldy peanuts, is the most potent human carcinogen known and is well documented to produce liver cancer. 

Hayes JD, Judah DJ, Neal GE. Resistance to aflatoxin B1 is associated with the expression of a novel aldo-keto reductase which has catalytic activity towards a cytotoxic aldehyde-containing metabolite of the toxin. Cancer Res 1993 53 3887-3894. 

Aflatoxins are the most feared of the mycotoxins-toxin-pro-ducing molds. There are four main aflatoxins B B2, G and Gj, of which B, is the most common and the most toxic. A high incidence of cancer, especially liver cancer, is associated with aflatoxin. 

Fig. P-44. Sporulation of Aspergillus flavus on a kernel of corn. This fungus produces aflatoxin. Aflatoxin (1) is associated with a high indicence of liver cancer, and (2) may be involved in some types of acute poisoning of children. (Courtesy, C. W. Hesseltine, USDA, Agricultural Research, Peoria, III.)...

Aflatoxin occurs most widely and has the greatest biological activity of this group of toxins. It is carcinogenic in several animal species and is the most potent hepatocarcinogen known for the rat and the rainbow trout (Wogan et al., 1974). Data from several population-based studies indicated that elevated aflatoxin intake is associated with an increased incidence of human liver cancer, e.g., in Mozambique (Van Rensburg et al., 1974) it may also be related to Reye s syndrome in Thailand (Shank, 1976). Afla-toxins can contaminate many commodities, e.g., peanuts, Brazil nuts. 

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