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A micrograph of an Aspergillus spore, a type of fungus that produces cancer-causing aflatoxin.

What are aflatoxins?

Aflatoxins are a family of toxins produced by certain fungi that are found on agricultural crops such as maize (corn), peanuts, cottonseed, and tree nuts. The main fungi that produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus, which are abundant in warm and humid regions of the world. Aflatoxin-producing fungi can contaminate crops in the field, at harvest, and during storage.

How are people exposed to aflatoxins?

People can be exposed to aflatoxins by eating contaminated plant products (such as peanuts) or by consuming meat or dairy products from animals that ate contaminated feed. Farmers and other agricultural workers may be exposed by inhaling dust generated during the handling and processing of contaminated crops and feeds.

Which cancers are associated with exposure to aflatoxins?

Exposure to aflatoxins is associated with an increased risk of liver cancer.

How can aflatoxin exposure be reduced?

You can reduce your aflatoxin exposure by buying only major commercial brands of nuts and nut butters and by discarding nuts that look moldy, discolored, or shriveled. To help minimize risk, the U.S. Food and Drug Administration (FDA) tests foods that may contain aflatoxins, such as peanuts and peanut butter. To date, no outbreak of human illness caused by aflatoxins has been reported in the United States, but such outbreaks have occurred in some developing countries.

Selected References

  • Food and Drug Administration. Bad Bug Book, Foodborne Pathogenic Microorganisms and Natural Toxins, Second Edition. Laurel, MD: Food and Drug Administration, 2012. Also available online. Last accessed December 28, 2018.
  • International Agency for Research on Cancer. Aflatoxins, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 100F. Lyon, France: World Health Organization, 2012. Also available online. Last accessed December 28, 2018.
  • National Center for Environmental Health. Aflatoxins, Understanding Chemical Exposures. Atlanta, GA: Centers for Disease Control and Prevention, 2012. Also available online. Last accessed December 28, 2018.
  • National Toxicology Program. Aflatoxins, Report on Carcinogens, Fifteenth Edition. Triangle Park, NC: National Institute of Environmental Health and Safety, 2021. Also available online. Last accessed December 5, 2022.
  • U.S. Department of Agriculture Grain Inspection, Packers and Stockyards Administration. Microtoxin Handbook. Washington, DC: Federal Grain Inspection Service, 2015. Also available online. Last accessed December 28, 2018.