Past and future in mycotoxin toxicology research
Before 1960 the toxicology of mycotoxins was mainly of concern to veterinarians, because outbreaks of mycotoxicoses resulted occasionally in considerable loss of livestock. By a wider use of biotests, preferably in mammals, a further decline of such intoxications probably will occur. Following the discovery of the carcinogenicity of some aflatoxins, the focus turned to human health. Screening tests for carcinogenicity are still in development. The test used most frequently is the Ames test on microorganisms. Unfortunately, many problems still must be resolved before an extrapolation of results from these tests to man is possible. Examination of the carcinogenic activity of mycotoxins in long-term animal experiments is often difficult due to lack of resources, lack of test material, and the toxicity of the compounds, which precludes administration of sufficiently high dose levels. The available data regarding a possible carcinogenic activity of several important mycotoxins, such as the trichothecenes or patulin, do not fulfill currently used criteria. Therefore further studies are needed. A new approach is determination of the binding capacity to DNA of suspected carcinogens, which seems to correlate well with carcinogenic potency. By this method, a high carcinogenicity of aflatoxin M1 can be deduced. However, the macromolecular-bound residues of aflatoxin B1, which may occur in tissues of domestic animals, most probably do not show carcinogenic activity. Although many questions are still unanswered, it seems that the numerous mycotoxins identified since 1960 are less toxic or carcinogenic and occur less frequently in food than do aflatoxins.