Mycotoxins are toxic, secondary metabolites of low molecular weight produced by naturally occurring fungi. The determination of which of the many known mycotoxins are significant can be based on their frequency of occurrence and/or the severity of the disease they cause, especially if they are known to be carcinogenic. Among the mycotoxins fitting into this major group are aflatoxins, produced by Aspergillus flavus, A. parasiticus, and other closely related fungi; fumonisins, produced by Fusarium verticillioides; and deoxynivelanol (DON or vomitoxin), produced by F. graminearum. Other fungal toxins include cyclopiazonic acid, zearalenone, patulin, ochratoxin, T-2 toxin, and certain ergot alkaloids produced by Claviceps purpurea. Aflatoxins are proven carcinogens, immunotoxins, and cause growth retardation in animals. Fusarium toxins, specifically fumonisins, are reported carcinogens and trichothecenes are reported immunotoxins. In the past, mycotoxin contamination of food was considered as a storage phenomenon whereby grains becoming moldy during storage allowed for the production of these secondary metabolites proven to be toxic when consumed by humans and animals. Subsequently, mycotoxins of several kinds were found to be formed during development of crop plants in the field. Many countries throughout the world have implemented a tolerance level for the presence of different mycotoxins in food for human and animal consumption. While economically strong countries have well-developed infrastructures for monitoring of internal food quality standards, people in developing countries are not protected by food quality monitoring and enforcement of safe standards within their countries. In less developed countries percentages from 22% fumonisin to 56% aflatoxin incidence have been reported. In developing countries, many individuals are chronically exposed to high levels of mycotoxin in their diet. No economically feasible processing procedures are currently available to remove toxins from foods that are already contaminated.
Mycotoxin losses and costs of mycotoxin management are overlapping areas of concern. Mycotoxin losses result from a) lowered animal production and any human toxicity attributable to the presence of the toxin, b) the presence of the toxin in the affected commodity which lowers its market value, and c) secondary effects on agriculture production and agricultural communities. Costs of mycotoxin management include testing and research necessary to try to prevent the toxins from appearing in food and feed products of affected commodities and research production practices.
Despite the extensive medical literature on the toxic effects of mycotoxins on humans and animals as well as the knowledge about the chemistry and modes of action of mycotoxins and their cost to the world, reliable solutions are still few and not applicable. As plant pathologists, this problem is still on our plate after almost 30 years of research. Economically effective solutions are those that are agriculturally and technologically based that exclude the fungi from the host and/or block the production of mycotoxins in the host substrates. Research is needed on 1) inexpensive and appropriate sampling and testing protocols for mycotoxins even at low concentrations, 2) identification and application of appropriate technologies for obtaining low grain moisture at harvest and maintaining low grain moisture during storage are needed, 3) chemical and biological control of mycotoxigenic fungi, 4) developing crop plant cultivars that are resistant (or at least not susceptible) in the field to infection by mycotoxin-producing fungi or the production of mycotoxins. Furthermore, with the complete genomes of several mycotoxigenic fungi, researchers worldwide are working at a rapid pace to identify mycotoxin biosynthetic and regulatory genes in order to find novel and long-lasting solutions in reduction or even elimination of mycotoxin production.
Presented at the 14th Hellenic Phytopathological Congress, Dalamanara Argolidas, Greece.