Any of the mold-produced substances that may be injurious to vertebrates upon ingestion, inhalation, or skin contact. The diseases they cause, known as mycotoxicoses, need not involve the toxin-producing fungus. Diagnostic features characterizing mycotoxicoses are the following: the disease is not transmissible; drug and antibiotic treatments have little or no effect; in field outbreaks the disease is often seasonal; the outbreak is usually associated with a specific foodstuff; and examination of the suspected food or foodstuff reveals signs of fungal activity.

The earliest recognized mycotoxicoses were human diseases. Ergotism, or St. Anthony's fire, results from eating rye infected with Claviceps purpurea. Yellow rice disease, a complex of human toxicoses, is caused by several Penicillium islandicum mycotoxins. World attention was directed toward the mycotoxin problem with the discovery of the aflatoxins in England in 1961. The aflatoxins, a family of mycotoxins produced by Aspergillus flavus and A. parasiticus, can induce both acute and chronic toxicological effects in vertebrates. Aflatoxin B₁, the most potent of the group, is toxic, carcinogenic, mutagenic, and teratogenic. Major agricultural commodities that are often contaminated by aflatoxins include corn, peanuts, rice, cottonseed, and various tree nuts. Aflatoxin Ergot and ergotism