Everything about Mycotoxins totally explained
Mycotoxin (from the
Greek μύκης (mykes, mukos) "fungus") is a
toxin produced by an organism of the
fungus kingdom, which includes
mushrooms,
molds and
yeasts. Most fungi are
aerobic (use oxygen). Fungi are found almost everywhere in extremely small quantities because of their
spores, and are most commonly
microscopically small. They consume
organic matter, wherever
humidity and
temperature are sufficient.
Where conditions are right, fungi
proliferate into
colonies and mycotoxin levels become high. Toxins vary greatly in their severity. Some fungi produce severe toxins only at specific levels of moisture, temperature or oxygen in the air. Some toxins are lethal, some cause identifiable diseases or health problems, some weaken the immune system without producing symptoms specific to that toxin, some act as allergens or irritants, and some have no known effect on humans. Some mycotoxins generally have more negative impacts on farm animal populations than on humans. Some mycotoxins are harmful to other micro-organisms such as other fungi or even bacteria;
penicillin is one example.
Mycotoxins can appear in the food chain as a result of
fungal infection of
crops, either by being eaten directly by humans, or by being used as livestock feed. Mycotoxins greatly resist decomposition or being broken down in digestion, so they remain in the food chain in meat and dairy products. Even temperature treatments, such as cooking and freezing, don't destroy mycotoxins.
Buildings are another source of mycotoxins. Public concern over mycotoxins increased following multi-million dollar
toxic mold settlements in the 1990s. The negative health effects of mycotoxins are a function of the
concentration, the duration of exposure and the subject's sensitivities. The concentrations experienced in a normal home, office or school are often too low to trigger a health response in occupants.
Food-based mycotoxins were studied extensively worldwide throughout the 20th century. 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.
Various wild mushrooms also contain an assortment of mycotoxins that can cause noteworthy health problems for humans who eat wild mushrooms without first properly identifying the specimens as safe edibles, in such cases sometimes causing mild to catastrophic
mushroom poisoning. The bulk of this article, however, is about mycotoxins that are found in fungi other than mushrooms.
Major groups of food toxins
Aflatoxins are produced by
Aspergillus species, and are largely associated with
commodities produced in the
tropics and
subtropics, such as
groundnuts, other
edible nuts,
figs,
spices and
maize. Aflatoxin B
1, 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 grow 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 alcoholic
fermentation and so isn't 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; and 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.
Stachybotrys and
Penicillium
Mycotoxin binding agents and deactivators
In the feed and food industry it had become common practice to add mycotoxin binding agents such as
Montmorillonite or
bentonite clay. To reverse the adverse effects of mycotoxins, the following criteria are used to evaluate the functionality of any binding additive:
- Efficacy of active component verified by scientific data
- A low effective inclusion rate
- Stability over a wide pH range
- High capacity to adsorb high concentrations of mycotoxins
- High affinity to adsorb low concentrations of mycotoxins interactions between toxins
- Affirmation of chemical interaction between mycotoxin and adsorbent
- Proven in-vivo data with all major mycotoxins
- Non-toxic, environmentally friendly component
Since not all mycotoxins can be bound to such agents, the latest approach to mycotoxin control is mycotoxin deactivation. By means of enzymes (
esterase,
epoxidase),
yeast (
Trichosporon mycotoxinvorans) or bacterial strains (
Eubacterium BBSH 797), mycotoxins are detoxified to non-toxic metabolites.
Mycotoxins killing humans
In 2004 in Kenya 125 people died and nearly 200 others were treated after eating
aflatoxin contaminated maize.
The deaths were mainly associated with homegrown maize that hadn't been treated with fungicides or properly dried before storage. Due to food shortages at the time, farmers may have been harvesting maize earlier than normal to prevent thefts from their fields, so that the grain hadn't fully matured and was more susceptible to infection.
Mycotoxins in pet food
There have been outbreaks of pet food containing mycotoxins in North America.
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 stealing from them by being administered a "Russian war-time mycotoxin", which alters his nervous tissue and renders him unable to access cyberspace.
Further Information
Get more info on 'Mycotoxins'.
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