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Mycotoxin (from Gk. μύκης (mykes) "fungus") is a toxin produced by a fungus under special conditions of moisture and temperature. These fungi are aerobic (use oxygen) and microscopic and, moreover, may colonise many kinds of food from the field to the table. Mycotoxins can appear in food and animal feed as a result of fungal infection of the crop, for example Fusarium ear diseases in cereals, or the infection of stored products. Not all fungi can produce mycotoxins. In addition some fungi are able to produce mycotoxins only in special conditions such as at specific levels of moisture, stress and the correct temperature. Even those with the ability to produce mycotoxins may not produce them all the time. The absence of mycotoxins doesn't ensure the absence of fungal spores, so it's possible for fungi to 'appear' when the temperature and humidity are right. In addition, the mycotoxins are very resistant to temperature treatments and to conventional food processes such as cooking, freezing etc.
Public concern over mycotoxins increased following some of the multi-million dollar "toxic mold" settlements of the late 1990s. The negative health effects of mycotoxins are a function of the concentration, duration of exposure and the subject's sensitivities. The concentrations experienced in a normal home, office or school are typically too low to trigger a health response in occupants. The mycotoxins are not gaseous (non-volatile), but rather they are associated with the spores and hyphae. Exposure typically occurs when contaminated food is eaten. In some cases this may include meat from animals that have themselves been fed contaminated feed.
In Europe, statutory levels of a range of mycotoxins permitted in food and animal feed are set by a range of European directives and Commission regulations.
Classification
Major groups of toxins include:
Aflatoxins produced by Aspergillus species, they are largely associated with commodities produced in the tropics and sub-tropics, such as groundnuts, other edible nuts, figs, spices and maize. Alflatoxin B1, the most toxic, is a potent carcinogen and has been associated with liver cancer.
Ochratoxin A is produced by Penicillium verrucosum, which is generally associated with temperate climates, and Aspergillus species which grows in warm humid conditions. Aspergillus ochraceus is found as a contaminant of a wide range of commodities including cereals and their products, fruit and a wide range of beverages and spices. Aspergillus carbonarius is the other main species associated in warm humid conditions found mainly on vine fruit and dried vine products particularly in the Mediterranean basin. It causes kidney damage in humans and is a potential carcinogen.
Patulin is associated with a range of fungal species and is found in moldy fruits, vegetables, cereals and other foods. It is destroyed by fermentation and so is not found in alcoholic drinks. It may be carcinogenic and is reported to damage the immune system and nervous systems in animals.
Fusarium toxins are produced by several species of the genus Fusarium which infect the grain of developing cereals such as wheat and maize. They include a range of mycotoxins including the fumonisins, which affect the nervous systems of horses and cause cancer in rodents, the trichothecenes, including deoxynivalenol, and zearalenone, the last two of which are very stable and can survive cooking. The trichothecenes are acutely toxic to humans, causing sickness and diarrhea and potentially death.
Mycotoxin binding agents
In the feed and food industry it has become common practice to add mycotoxin binding agents. To reverse the adverse effects of mycotoxins following criteria are used to evaluate the functionality of any binding additive:
1. Efficacy of active component verified by scientiffic data 2. A low effective inclusion rate 3. Stability over a wide pH range 4. High capacity to adsorb high concentrations of mycotoxins 5. High affinity to adsorb low concentrations of mycotoxins interactions between toxins) 6. Affirmation of chemical interaction between mycotoxin and adsorbent 7. Proven in-vivo data with all major mycotoxins 8. Non toxic, environmentaly friendly component
Mycotoxins in fiction
A fictional application of a mycotoxin occurs in William Gibson's seminal novel Neuromancer, in which Case, the anti-hero, is punished by some of his business partners for trying to steal from them by being administered a "Russian mycotoxin", which alters his nervous tissue and renders him unable to access cyberspace.
Side note
Strictly speaking, ethanol, also known as ethyl alcohol or grain alcohol, that is produced when certain species of yeast (most importantly, Saccharomyces cerevisiae) metabolize sugar in the absence of oxygen, is a mycotoxin as well.
External links
Toxicology | Mycology | Mycotoxins | Mykotoxin | Mycotoxine | マイコトキシン
"Mycotoxin"