Aflatoxins are toxic and carcinogenic metabolites produced by species of Aspergillus, but Aspergillus flavus and A. parasiticus are of most concern. Aflatoxins were first identified in the 1960s and compose a family of toxic compounds. Aflatoxin B1 Aflatoxin B1 is the most carcinogenic and best studied of the compounds. The toxic effects include acute hepatitis, immunosuppression, and hepatocellular carcinoma. In humans, the risks associated with aflatoxin consumption are well documented, and the International Agency for Research on Cancer (IARC) has designated aflatoxin as a human liver carcinogen.
Because of these toxic effects, the Food and Drug Administration regulates the aflatoxin concentration in food and feed. Commodities or food exceeding 20 ppb (ug/kg) cannot move in US trade. A metabolite of aflatoxin (M1) can appear in milk of cows fed contaminated food. The allowable level of aflatoxin M1 in milk is less than 0.5 ppb. Other countries have posed lower acceptable limits. Forty-eight countries have specific regulatory levels for total aflatoxins in foodstuffs and 21 having regulations for aflatoxins in feedstuffs.
Aflatoxins belong to a class of compounds known as mycotoxins. Mycotoxins may be defined as small molecular weight compounds produced by fungi that are toxic to animals and humans. Over 300 mycotoxins are known and they are produced by several species of fungi. Most of the mycotoxins of concern are produced by three genera: Aspergillus, Penicillium, and Fusarium.