Aflatoxins contaminate a wide range of agricultural products. They occur mostly in nuts, peanuts butter and oleaginous seeds, but can contaminate also cereals, milk, and cheese.
Aflatoxins are mainly produced by Aspergillus flavus and A. parasiticus, and the most common naturally are aflatoxins B1, B2, G1, and G2. Especially, aflatoxin B1(AFB1) is the most toxic compound, being related to hepatocellular carcinoma (HCC) in humans. There is an increasing awareness of the hazards to both human and animal health of aflatoxins present in food and feed. They are listed as group I carcinogens by the International Agency for Research on Cancer (IARC, 1993). Aflatoxins are regulated in many countries and legal limits have been established by the European Commission for the different compounds and different food commodities.
Fumonisins are natural contaminants mainly of maize grains and derived products worldwide. Fumonisins are produced by species of Fusarium genus, mostly F. verticillioides and F. proliferatum. The most abundant species in nature is Fumonisin B1 (FB1), followed by Fumonisin B2 (FB2) and fumonisin B3 (FB3). They and are carcinogenic to animals and potentially also to humans. Typical toxicoses caused by fumonisins are leukoencephalomalacia in horses and pulmonary edema in pigs. They are also suspected to play a role in esophageal cancer in humans (IARC group 2B). The European Commission has regulated the occurrence of fumonisins in food and feed products with special emphasis to maize and derive products and other cereals.
Trichothecenes are tricyclic sesquiterpenes, divided in type A and B according with the absence/presence of a cheto group at C-8 of the epoxide ring. They are natural contaminants of cereals, and constitute the largest group of mycotoxins produced by Fusarium. The most common trichothecene type B in cereals is deoxynivalenol (DON), mainly produced by F. graminearum, and F. culmorum. Among trichothecenes type A, T-2 and HT-2 toxins are most harmful compounds produced by Fusarium species, mainly F. sporotrichioides and F. langsethiae. The trichothecenes are potent inibithors of proteic synthesis. Deoxynivalenol is the most common contaminant of cereals and also commonly known as vomitoxin. The commercialization of food commodities contaminated by DON is subjected to legal limits regulated by European Commission in cereals and by-products, while limits for T-2 and HT-2 toxins are only recommended.
Ochratoxin A (OTA) is the most toxic member of the ochratoxins group and one of the most important mycotoxins isolated and described to the present day. Teratogenic, embryotoxic, genotoxic, neurotoxic, immunosuppressive, carcinogenic (IARC group 2B), and nephrotoxic effects were also observed for OTA. OTA, mainly produced by Aspergillus ochraceus, Penicillium verrucosum, Aspergillus carbonarius, and, at lesser extent, by different species of black Aspergilli, occurs on several common commodities in human diets, including grapes, barley and green coffee beans. Moreover, it has been associated to Nephropathy Endemic of Balkans, and it is suspected to cause tumors of urinary system and interstizial chronic nephritis in Northern Africa. Regulation for OTA was established by the European Commission for several food commodities, among which raw cereal grains and cereal derived products.