They are most commonly found on corn, peanuts and other nuts, and products made from these ingredients. The moulds that produce aflatoxins are invisible to the naked eye, and grow in conditions of high humidity.

The highest level of aflatoxins allowed in nut products is 15 mg/kg (microgram per kilogram) and in all other foods 5 mg/kg.

Health effects
Aflatoxins are potent carcinogens in animals. It is thought that the high incidence of liver cancer in some African and Asian countries is caused by high levels of aflatoxins in the diet.

Alternatives
Proper drying, storage and processing prevents the growth of moulds on foods and the formation of aflatoxins. Do not eat nuts that have become damp in storage.