Animals vomitoxin toxicity

Contamination occurs primarily in wheat, barley, rye, and maize. Type A trichothecenes include mainly T-2 toxin, HT-2, and diacetoxyscirpenol (DAS) mycotoxins of the group B include mainly 4-deoxynivalenol (DON), commonly known as vomitoxin, and nivalenol (NIV). Toxic effects include nausea, vomiting, visual disorder, vertigo, throat irritation, and feed refusal in farm animals. The most toxic is T-2, followed by DAS and NIV, with DON being the least toxic in acute toxicity studies but the most widespread in grains worldwide and therefore the most studied. Issues related to chemical and physical data, occurrence, toxicity, absorption, distribution, and metabolism of trichothecenes are reviewed in WHO (89) and IARC (34). Physicochemical data for some selected Fusarium toxins is given by Sydenham et al. (90). The molecular structures of the main trichothecenes are shown in Fig. 9. 

Other mycotoxins, including DAS, DON, and ochratoxin, are not of major economic importance although they can be toxic to food-producing animals. DAS causes necrosis and erosion of the oral mucous membranes. Consequently, affected animals exhibit feed refusal and have impaired growth. DON (also called vomitoxin ) induces vomiting and feed... 

The toxic efiects of the 12,13-epoxytrichothecenes are associated with the more highly oxidized members such as T-2 toxin (9.8) and vomitoxin (deoxynivalenol) (9.6) together with their macrocychc esters. The symptoms of alimentary toxic aleukia in test animals (cats) were detected on administration of T-2 toxin at a level of 0.08 mg kg per day. Structure activity studies on T-2 toxin revealed a requirement for the presence of the 12,13-epoxide and the 9-ene. The compounds exert their activity by the inhibition of protein synthesis. The trichothecenes interfere with the peptidyl transferase in the ribosomes. 

One of the main concerns regarding vomitoxin is whether it causes any chronic toxic effects, that is, effects when low concentrations are consumed over a long period of time. One typical chronic effect is cancer. So far, no studies have shown that vomitoxin can cause cancer however, no chronic studies have been performed with vomitoxin. Vomitoxin has been related to cancer of the esophagus in humans in Transkei, Africa ( ), but this study only involved a few samples and no animal studies have corroborated this relationship. Another chronic effect that is a concern with vomitoxin is that of immunosuppression, that is, an effect which lowers the body s ability to resist disease. A Japanese study (10.) has demonstrated that when small amounts of T-2 toxin, a trichothecene similar to vomitoxin, were administered to cats, a significant decrease in the white blood cell count resulted. If vomitoxin is found to have a similar immunosuppressive effect at low concentrations, it may become regarded as a human health hazard. 

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