Submitted to: Meeting Abstract
Publication Type: Review Article
Publication Acceptance Date: 2/1/2003
Publication Date: 2/28/2003
Citation: Bhatnagar, D., Payne, G.A., Cleveland, T.E., Robens, J.F. Mycotoxins: Current issues in U.S.A. [abstract]. Proceedings of the 2nd Second World Mycotoxin Forum, February 17-18, 2003, Noordwijk, The Netherlands.
Technical Abstract: Mycotoxins are secondary metabolites produced by filamentous fungi that cause a toxic response (mycotoxicosis) when ingested by higher animals. Aspergillus, Fusarium, and Penicillium are the primary fungal genera that produce these toxins in the human food chain. Mycotoxins can contaminate human foods and animal feeds through fungal growth prior to and during harvest, or from improper storage following harvest. Based on health concerns, the U.S. Food and Drug Administration (FDA) has set regulatory limits on the permissible levels of aflatoxins in food and feed, and guidelines have been issued for deoxynivalenol, fumonisins, and patulin. FDA has issued no regulations or guidelines for ochratoxin A content at this time. These regulatory guidelines (within U.S. as well as those enforced internationally) and crop losses due to disease caused by mycotoxigenic fungi have put a tremendous economic burden on U.S. agriculture. It is estimated that the mean direct economic annual costs of crop losses from just three mycotoxins, namely aflatoxins, fumonisins, and deoxynivalenol, are $932 million. Therefore, there is significant emphasis being placed on devising (1) sensitive, specific, non-destructive, and rapid procedures for detecting fungal and toxin contamination of crops; and (2) effective strategies for controlling pre-harvest contamination and post-harvest decontamination of commodities. New biosensors are being developed using fiber optics, hyperspectral, and near infrared imaging for rapid and sensitive detection of mycotoxins or toxigenic fungi. The genetics and biology of aflatoxins, trichothecenes, and fumonisins biosyntheses have been investigated in significant detail, and many of the genes and/or enzymes involved in toxin formation have been identified. Genomic efforts, such as Expressed Sequence Tag (ESTs) microarrays, cosmid clone sequencing, chromosome sequencing, and large-scale whole genome sequencing on toxigenic and non-toxigenic Aspergillus and Fusarium species have been made in recent years. Significant in-roads have been made in establishing various control strategies, such as development of atoxigenic biocontrol fungi that can out compete toxigenic fungi. Potential biochemical and genetic resistance markers have been identified in crops, particularly in corn, which are being utilized as selectable markers in breeding for resistance to aflatoxin contamination; and prototypes of genetically engineered crops have been developed that contain genes for resistance. In addition, specific mode of action of mycotoxins in human health is being examined in detail. For example, the immunosuppressive nature of mycotoxins, the exposure to multiple mycotoxins, the interaction of mycotoxins with dietary components, role of fumonisins in cancer, and the risks of ochratoxin and cyclopiazonic acid exposure is being elucidated. The role of fungi and the relevant mycotoxins, if any, on indoor air quality is being examined. And, with the events of bioterrorism in the last decade, particularly with respect to the potential for use of mycotoxins as bioterrorism agents, rapid detection and detoxification procedures for these compounds are being developed.