Mycotoxins are toxic substances produced by fungi, mainly the molds. They could be regarded as silent killers of humans and animals since some of them are potent carcinogens. Molds may be present without the production of mycotoxins but mycotoxins cannot be produced in the absence of molds.
Health Effects Associated with Mycotoxins
Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. Mycotoxins are capable of causing disease in many species of birds, mammals as well as other non-avian species, and humans. The toxicity of the mycotoxins varies considerably with the toxin, the animal species exposed to them, and the extent of exposure, age, and nutritional status.
Mycotoxins are not necessarily produced whenever feed or forage becomes moldy, but evidence of mold indicates a risk of toxins. Production of mycotoxins is dependent upon many factors including the type of producing fungus and environmental conditions, such as the substrate, water activity (moisture and relative humidity), and duration of exposure to stressful conditions, and microbial ecological interactions. Species of Aspergillus are well known producers of mycotoxins. These include Aspergillus ochraceus, ochratoxin; Aspergillus fumigatus, fumitremorgins, gliotoxin, and verrucologen; Aspergillus versicolor, sterigmatocystin, and Aspergillus flavus and Aspergillus parasiticus, aflatoxins. Sterigmatocystin may also be produced by A. flavus, A. nidulans, A. rugulosus, and A. unguis.
Mycotoxins can be formed by molds in the field prior to harvest, in transport or subsequently during storage or feed manufacture. Mycotoxins can also crop up during a wet harvest or in moist storage conditions. Mycotoxins are often invisible, tasteless, chemically stable and resistant to temperature and storage.
Some mushrooms or toadstools produce mycotoxins as well. Those mycotoxins are different from those produced by molds, since mushroom toxins poison people when they are consumed by people as neuronal, liver, blood or stomach toxins. Some mycotoxins are very potent, such as that from Amanita species (the death cap genus). Mushrooms in this genus have a significant typical wrapping foot or enlarged foot blob, a ring at the middle of the stalk, and some with colorful caps with or without warts.
Mycotoxins Exposure, Eradication and Control
Mycotoxins are non-volatile but exposure may take place through inhalation or skin contact with toxin-carrying spores or mycelium. The primary route for mycotoxins poisoning is through ingestion of contaminated food or feed. Many symptoms and human health effects attributed to inhalation of mycotoxins have been reported including: mucous membrane irritation, skin rash, nausea, immune system suppression, acute or chronic liver damage, acute or chronic central nervous system damage, endocrine effects, and cancer. More studies are needed to get a clear picture of their health effects. However, it is clearly prudent to avoid exposure.
Mycotoxins are relatively stable and may survive most processing operations. The best way to control their production is to control mold growth by eliminating moisture.