An aflatoxin is a
poisonous cancer-causing compound produced by the
fungal species Aspergillus flavus and
Aspergillus parasiticus, both of which grow easily on
beans,
grains (particularly
corn), and
peanuts when they are inappropriately stored in
warm,
humid conditions. The
fungi occur naturally in
soil and
decaying leaves,
grass, and other
vegetation; if they
infect a growing plant, they usually do so through a
wound created by an
insect.
This toxin is a powerful liver carcinogen. The presence of aflatoxins in contaminated food supplies is thought to contribute to the high levels of liver cancer in undeveloped and developing countries in the tropics.
There are over a dozen different types of aflatoxin, but aflatoxin B1 is considered to be the most poisonous.
The United States tests domestic corn, sorghum, wheat, peanuts and soybeans for the presence of Aspergillus toxins, and the USDA requires that all corn grown for export must be tested. One previously-common testing method looked for the toxin indirectly by looking for kojic acid, another Aspergillus compound, which will glow under a black light. The kojic acid test has been found to be unreliable, so today more expensive laboratory methods to find aflatoxin directly in grain or bean samples are used.
References
Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals
Simpson, Beryl Brintnall and Molly Conner-Ogorzaly. 1986. Economic
Botany: Plants in Our World. New York, NY, McGraw-Hill Publishing Co.
http://www.usda.gov/gipsa/newsroom/backgrounders/b-aflatox.htm
http://www.perskyfarms.com/aflatoxi.htm