The Control of Aflatoxin Residues in Food of Animal Origin

Apart from its presence in primary agricultural products, aflatoxin and its metabolites may be detected in animal tissues and milk. As the aflatoxins are toxic and extremely carcinogenic, control of food contamination with them is imperative. Either the primary aflatoxins (H 1,B2, G1 andG2) or their metabolites (M1 and M2) have been recovered from several animal tissues and milk. The bio-assay techniques which are currently available are not suitable for routine screening purposes. The chemical assay techniques, although more accurate, faster and more specific, have many serious drawbacks particularly in relation to efficiency of extraction. Further steps in assay procedures have been refined and standard solutions. in chloroform are stable for at least 4 months at —10°C. Taking into account the sensitivity of current techniques and the biological activity of aflatoxins, a level of I ig kg' is recommended for statutory purposes. Control in finished animal products is discussed. The most effective procedure for prevention of contamination of animal products is to exercise control of intake of the toxin. Aflatoxin, with its potent carcinogenic activity in many species1 and widespread natural occurrence, ranks as the most important and potentially dangerous of the currently identified mycotoxins. Apart from the ingestion of aflatoxin in oilseeds, cereals and other agricultural products in which the fungus (Aspergillus flavus) is growing, there is the possibility of ingesting aflatoxin and its metabolic transformation products in foods on which the fungus is not growing. Foods derived from animals which are ingesting aflatoxin may contain toxic products and the potential danger to man is enhanced because the animals concerned may show no outward signs of disease. Discussion of the methods of controlling contamination of animal products includes a consideration of the occurrence and methods of identifying the toxins. OCCURRENCE OF AFLATOXINS IN FOOD OF ANIMAL ORIGIN The four most commonly found 'primary' aflatoxins in oilseeds and cereals are afiatoxin B1, B2, G1 and G2. One or all of these compounds has been found in a wide variety of agricultural products, although groundnuts appear to be the most commonly contaminated. Because of this widespread distribution ingestion of these aflatoxins by animals is relatively common. * Present address: l.C.I. Industrial Hygiene Research Laboratories, Alderley Park, Macdesfield, Cheshire, England.