Mycotoxins definition

Hesseltine, C.W. (1979) Introduction, definition and history of mycotoxins of importance to animal production. In Interactions ofMycotoxins in Animal Production. N ational Academy of Sciences, Washington, DC, pp. 3-18. 

An overview of the literature shows that in the majority of cases, CA did yield accurate predictions of combination effects, even with mixtures composed of chemicals that operate by diverse modes of action. The studies available were dealing with mixtures of chemicals having an unspecific mode of action (membrane disturbance or narcosis) or with pesticides, mycotoxins, or endocrine disruptors. In ecotoxicol-ogy, CA usually produced more conservative predictions than IA. There are indications that this is true also for mammalian toxicology, but more data are needed to come to more definitive conclusions. The validity of CA or IA was confirmed for individual-based endpoints like growth or reproduction, but also for effects at the cellular or subcellular level and for community-based endpoints. 

In August 1981, based on limited physical evidence, the USA announced that trichothecene mycotoxins had been used - but the findings were less than convincing to the scientific conununity and the issue became extremely contentious. This controversy was never totally resolved and no definitive evidence was found (Bajgar, 2006). 

Despite denials by the governments involved, the United States went public with charges that chemical warfare had been used in Southeast Asia and Afghanistan in 1980. Problems with the collection of samples and the remoteness of the sites, however, prevented definitive evidence from being obtained. Furthermore, the later identification, discussion, and media debate over the origin of possible trichothecene mycotoxins in Southeast Asia also took away a significant portion of the public interest in the alleged use of conventional chemical munitions. 

Trichothecene mycotoxins are secondary metabolites of various fungal species. Structures of some trichothecene mycotoxins of interest to the US ARMY are given in Figure 1. Several methods have been reported for the analysis of these toxins (1-11, 15). Of these, mass spectrometry techniques are both sensitive and definitive when applied to toxicologic and environmental samples. With current technology, the most sensitive and qualitatively definitive analytical technique for the determination of these toxins is derivatization with an electron deficient moiety followed by analysis with negative ion chemical ionization gas chromatography-mass spectrometry (NICI-GC/HS). 

The analytical procedure that is used by this laboratory for the analysis of simple Fusarium mycotoxins will be reported separately. However, the analytical scheme is outlined in Figure 2. The method is very arduous due to several sample clean-up steps which necessitates transfer of the sample between containers. The trichothecenes and their derivatives have a tendency to adhere to glass and can be quantitatively transferred only with numerous methanol washes. While the analytical method is both sufficiently sensitive and definitive for the program requirements, the sheer amount of human manipulation required for the completion of this analysis makes it somewhat unreliable if implemented without a responsible quality assurance and quality control program. 

This definition of food contaminants encompasses a very broad range of chemical substances, many of which are covered by other articles in this Encyclopedia, particularly natural toxins, mycotoxins, pesticides, antibiotics, and metals (both individually and collectively). Consequently, this article will give an overview of chemical contaminants in foods, dealing particularly with agrochemical and veterinary drug... 

The extractable conjugated or bound mycotoxins are not currently regulated by legislation (Berthiller et al., 2013). Further studies are required on determination of modified mycotoxins and on their stability, transformation, toxic properties and bioavailability. With respect to regulation, a possible approach in the future could be the definition of the sum of all relevant forms of each mycotoxin, including its relevant derivatives. 

Rychlik, M., Humpf, H.-U., Marko, D., Danicke, S., Mally, A., Berthiller, R, et al. (2014). Proposal of a comprehensive definition of modified and other forms of mycotoxins including masked mycotoxins. Mycotoxin Research, 30, 197-205. 

Toxins are natural venoms produced by the metabolic activities of living organisms. These compounds can be small molecules, peptides, or proteins and are capable of causing damage when introduce into the body. This definition includes a wide range of molecules with different structure and activity, such as mycotoxins, produced by fungus marine toxins, produced by dinoflagellates and venoms (peptidic toxins) secreted by some animals, such as snakes, scorpions, and bees. 

This conclusion was reached rather more definitely by a study commissioned by the Canadian government. Dr Bruno Schiefer, a toxicologist at the University of Saskatchewan, visited Thailand to interview refugees and collect samples from border areas near the sites of alleged attacks. He found that the events reported to have taken place at the time of the alleged attacks could not be explained on the basis of naturally occurring phenomena. Shiefer argued that mycotoxins did not occur naturally in the environment. In his view, mycotoxin contamination could not have resulted naturally. 

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