What Is Aflatoxin?

Aflatoxins are a family of naturally occurring toxins produced primarily by Aspergillus flavus and Aspergillus parasiticus. They are among the most potent carcinogens known, classified as Group 1 human carcinogens by the International Agency for Research on Cancer. The name comes from "A. flavus toxin," reflecting the mold species that first drew scientific attention.

In household settings, aflatoxin contamination is rare. These compounds thrive in warm, humid agricultural environments — corn, peanuts, cottonseed, and tree nuts stored under poor conditions are the most common sources. A homeowner who discovers mold in their basement or on drywall is almost never dealing with aflatoxin-producing mold.

The distinction matters because not all Aspergillus species produce aflatoxins, and aflatoxin production itself is highly dependent on environmental conditions. Indoor Aspergillus growth can still cause respiratory problems through allergens and other mycotoxins — but the specific aflatoxin risk applies mainly to food contamination scenarios.

If you suspect aflatoxin exposure from food, the concern is liver toxicity with long-term ingestion. Acute exposure at very high doses can cause acute aflatoxicosis — liver failure, internal bleeding, and death — though this is exceedingly rare in developed countries with food safety regulations. For indoor mold problems, the health concerns are typically allergen and mycotoxin exposure more broadly, not aflatoxin specifically.