Mycotoxins: Biosecurity and Food Safety (NC129)

NON-TECHNICAL SUMMARY: Mycotoxins are metabolites of fungi that can adversely affect animal and human health. Mycotoxins can be produced in grain during storage or processing, but are most frequently associated with fungal infection that occur before harvest. Environmental factors that determine fungal infection and mycotoxin production are complex. Generally, a basal level of mycotoxins is present in US grain; however, in some years, environmental conditions lead to localized or widespread outbreaks of mycotoxin contamination. However, there is no organized monitoring system for tracking the incidence and severity of mycotoxin contamination at either the national or regional levels. Although breeding and transgenic technologies have shown promise for reducing the risk of mycotoxin contamination of grain, to date no commercial variety of any major US crop is available with either genetic or transgenic resistance to mycotoxin contamination. The need, as indicated by stakeholders, and likely impacts from completion of the work. For grain and livestock producers, the most important issues are preventing mycotoxin contamination and reducing the effects of mycotoxins on livestock. For grain buyers and food processors, the primary issue is being able to rapidly assess the quality of grain as pertaining to mycotoxins and mycotoxigenic fungi. The worst-case scenario for these stakeholders is to own millions of bushels of corn contaminated with unacceptable levels of aflatoxins and fumonisins, or wheat with excessive concentrations of deoxynivalenol (DON). Rapid methods to detect mycotoxins at the first points of sale (elevators) as well as methods to detect mycotoxigenic fungi in the commodity (e.g. DON-producing Fusarium in barley) would address these concerns. Additionally, these stakeholders need cost-effective methods to detoxify mycotoxins and prevent further deterioration of contaminated grain. The lowering of tolerance limits for mycotoxins in overseas markets has increased the burden for grain buyers and food processors; currently, levels of mycotoxins that are acceptable for some US products are unacceptable in European and Asian markets resulting in non tarrif trade barriers. New methods to monitor and treat contaminated grain would benefit domestic consumers and would allow American commodities to compete more effectively in foreign markets. Finally, workers who are responsible for animal and human health need information about the toxicity, carcinogenicity, modes of action, and biomarkers of exposure and disease for all categories of mycotoxins. This information would be used to train health-care providers to identify exposure and treat related disease, as well as to develop accurate risk assessment recommendations.

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APPROACH: Confirmatory Techniques: Instrumental techniques are essential for confirming the presence of mycotoxins in cereal grains, and for more accurate quantification of the amounts of mycotoxins present. MI, PA, ARS will continue a collaborative effort to validate new methodologies, such as chromatographic techniques, capillary electrophoresis and mass spectrometry. <P>Mechanistic Studies: The fumonisins have received the most attention by NC129 in the past. Rodents will be used as a model for carcinogenicity, teratogencity and immunotoxicity for the fumonisins and DON. Since several trichothecenes have been identified by CDC as biosecurity risks, it is critical to be able to use animal assays in conjunction with cell systems to evaluate potential natural or intentional contamination of feeds and foods by these agents. Animal assays will be critical to IA in assessing if decontamination and detoxification strategies designed in objective 3 are successful. We will continue to assess acute toxicity of fumonisins and the DON in mouse and other animal models in oral feeding studies with naturally contaminated foods or purified toxin. Using the mouse splenocyte suspension, enumeration of antibody response to T-dependent antigen will be assessed with hemolytic plaque assay in response to sheep RBCs. Serum corticosterone levels of all mice were measured using commercial enzyme immunoassay with an effect of exercise. Define the regulation of mycotoxin biosynthesis and the molecular relationships between mycotoxigenic fungi, through microarray techniques and statistical analysis.