Aflatoxins in animal and human health

Aflatoxins remain as a threat to the health of livestock as well as humans by their continuing intermittent occurrence in both feeds and foods. The finding that aflatoxin-contaminated feeds, and eventually purified aflatoxins, were carcinogenic in rats and trout initiated a multitude of studies in search of the role of these toxins in human liver disease, especially cancer. Although aflatoxins have caused acute liver disease in humans, epidemiologic evidence of the involvement of aflatoxins in PLC has not been clarified. Earlier studies did not consider that the hepatitis B virus (HBV) may have contributed to the PLC in the selected populations. Although later studies that did include measurement of the HBV antigen in serum provided conflicting evidence for the role of aflatoxin in PLC in these populations, the latest and most comprehensive study found no association between aflatoxin exposure and PLC mortality. The technological advances and findings of the chemical, immunologic, and metabolic activities of aflatoxins such as binding to DNA and protein to form adducts, development of monoclonal antibodies, and mutational specificity of the genotoxic compounds will, it is hoped, help to clarify the role of aflatoxin as a risk factor, among many others, in the development of primary liver cancer in humans. Aflatoxicosis of animals is usually manifested by pathologic changes in the liver, but they have been found to be carcinogenic and teratogenic as well as causing impaired protein formation, coagulation, weight gains, and immunity. The importance of the carcinogenic effect in livestock is diminished because they are not fed contaminated diets for a sufficient time prior to marketing for slaughter. Animals are variably susceptible to aflatoxins, depending on such factors as age, species, breed, sex, nutrition, and certain stresses. Swine, cattle, and poultry are the domestic species of greatest economic concern in terms of aflatoxicosis. In all species, the evidence of disease is a general unthriftiness and reduction in weight gains, feed efficiency, immunity, and production. More conclusive evidence of aflatoxin involvement in disease includes acute to chronic liver disease with concomitant increases in specific liver enzymes in the serum. In cattle, milk production is affected, but of greater significance is that the aflatoxins in feeds can be rather efficiently converted to toxic metabolites in milk, with even small amounts being readily detectable. The poultry industry probably suffers greater economic loss than any of the livestock industries because of the greater susceptibility of their species to aflatoxins than other species.(ABSTRACT TRUNCATED AT 400 WORDS)