Although aflatoxins are known to cause cancer in animals, the United States Food and Drug Administration (FDA) allows them at low levels in nuts, seeds, and legumes because they are considered unavoidable contaminants.

The FDA believes occasionally eating small amounts of aflatoxin poses little risk over a lifetime. It is not practical to attempt to remove all traces of aflatoxin from food products in order to make them safer.

The mold that produces aflatoxin may be found in the following foods:

• Peanuts and peanut butter
• Tree nuts, such as pecans
• Corn
• Wheat
• Oil seeds, such as cottonseed

Aflatoxins ingested in large mounts may cause acute liver damage. Chronic intoxication may lead to weight gain or weight loss, loss of appetite, or infertility in men.

To help minimize risk, the FDA tests foods that may contain aflatoxin. Peanuts and peanut butter are some of the most rigorously tested products because they often contain aflatoxins and are widely eaten.

You can reduce aflatoxin intake by:

• Buying only major brands of nuts and nut butters
• Discarding any nuts that look moldy, discolored, or shriveled

Murray PR, Rosenthal KS, Pfaller MA. Pathogenesis of fungal disease. In: Murray PR, Rosenthal KS, Pfaller MA, eds. Medical Microbiology. 9th ed. Philadelphia, PA: Elsevier; 2021:chap 58.

National Cancer Institute website. Aflatoxins. www.cancer.gov/about-cancer/causes-prevention/risk/substances/aflatoxins. Updated July 3, 2024. Accessed January 14, 2025.

Patierno SR. Environmental factors. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 10.

Updated by: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.