Fusarium mycotoxin contamination in the human food chain
Posted: 1 September 2015 | | No comments yet
Mycotoxin contamination poses an intractable problem in agricultural production. WHO estimates that over 25% of global food crops are significantly contaminated with mycotoxins causing annual losses of around 1 billion metric tons of food. Mycotoxins are formed during cereal growth or in post-harvest storage; so this problem may increase as a result of climate change with weather extremes favouring plant stress and mould growth.
Mycotoxins are secondary metabolites of filamentous fungi which commonly contaminate agricultural crops including all major cereal grains as well as ground nuts and fruits. Over 300 mycotoxins have been identified but the predominant species that lead to mycotoxin contamination in cereals are Aspergillus, Penicillium and Fusarium. In temperate climates such as Europe and North America, Fusarium moulds are the most common fungal species producing a host of Fusarium mycotoxins. Among them trichothecene mycotoxins comprise the most important group in terms of prevalence and contamination levels. While type A trichothecenes, namely T-2 and HT-2 toxin are more potent toxins, it is the type B trichothecenes, especially deoxynivalenol and nivalenol, that are most commonly detected in cereals. Furthermore, zearalenone and fumonisons are a commonly detectable Fusarium mycotoxin.
The main toxic effects of low and moderate trichothecene exposure are gastrointestinal disturbances, impaired intestinal barrier function and impaired innate immunity. Fumonisins interfere with cellular synthesis of glycol-sphingosines and cause liver and kidney toxicities whereas zearalenone possesses weak oestrogenic activity. Based on intensive toxicity studies in experimental and farm animals and applying safety factors to ensure safe consumption for humans, tolerable daily intakes (or TDIs) are calculated for several mycotoxins. The TDI estimates the quantity of mycotoxin (expressed as μg/kg body weight/day) which someone can be exposed to daily over a lifetime without it posing a significant risk to health…