Chemistry of Aflatoxins
The Aflatoxin/Foodborne Diseases Correlation
With relation to intoxications and infections, there are basically two types of food-borne diseases. Intoxications are food-borne diseases caused by the consumption of intoxicants like:
- (a) Synthetic insecticides (chemicals) sprayed in farms, or
- (b) Naturally poisonous plant or animal tissues, or
- (c) Metabolic toxic products formed by bacteria, algae and fungi.
On the other hand, infections are caused by the enterotoxigenic or invasive penetration of pathogenic microorganisms into the body, via foods, and the consequent production of mycotoxins. Aflatoxins are mycotoxins produced by A. flavus and A. parasiticus species of fungi which colonise and contaminate crops before harvest or during storage in generally hot and moist environments. Host crops for these fungi species include maize, sorghum, groundnut, rice, wheat, cassava, pistachio, cashew, almond, cottonseed, turmeric, chilli, peppers and even the cattle fodder. Aflatoxin can enter in form of feed in cattle farms or dairies too if made from affected fodder and oil seed cakes (ground nut, cottonseed, etc.). Should animals graze aflatoxin-contaminated feed, obviously they would produce milk containing a different form of aflatoxin as the result of the metabolisation of the original molecule in the consumed feed. Eggs and other poultry products can be contaminated in the same way with aflatoxins when birds consume such kind of affected grains.
The disease can be observed in humans and animals, including birds, due to the consumption of aflatoxin-contaminated foods or feeds: this disease is called aflatoxicosis. It is worth mentioning that the presence of Aspergillus fungi does not always indicate harmful levels of aflatoxins. Actually, this contamination might be safe to some extent if present in minor amount, but the consumption of Aspergillus- contaminated food or feed is always risky (Hudler 1998). Aflatoxins are heterocyclic compounds and exert toxic effects after consumption in the body within several ways. High-level aflatoxin consumption can give rise to hepatic necrosis, resulting later in cirrhosis or carcinoma of the liver. Generally, the patient might be in very serious condition in absence of cures at early stages: consequences might lead the subject to coma and even death. It has been observed that adult humans can tolerate these mycotoxins with low consequences, while children may suffer serious damages and animals are not so resistant (Abbas 2005; Williams et al. 2004). Aflatoxins are among the most carcinogenic substances known (Hudler 1998).