Descriptions of some of the most commonly found mycotoxins in food and feed that may be of concern to consumer food safety.
The toxicological effects of the toxins are assessed by international bodies such as the European Food Safety Authority and the Joint Expert Committee on Food Additives. Individual assessments can be found on their respective websites. Maximum legal levels exist for certain mycotoxins in order to ensure consumers’ protection from any adverse health effects.
Aflatoxins are produced by the Aspergillus species of fungi, principally A. flavus, and A. parasiticus. Crops that are frequently affected include cereals such as maize, oilseeds including peanuts (groundnuts), various spices, figs and other dried fruit, and tree nuts such as hazelnuts, almonds, pistachios and Brazil nuts. The toxins can also be found in the milk of animals that are fed contaminated feed, in the form of aflatoxin M1.
Aflatoxins, and in particular aflatoxin B1, are genotoxic and carcinogenic, and can cause liver cancer in humans.
Ochratoxin A is produced by several fungi, including those from the genera Penicillium and Aspergillus. Contamination of food commodities, including cereals and cereal products, coffee, dry vine fruits, wine and grape juice, spices and liquorice, occurs world-wide. Ochratoxin A is a storage mycotoxin, as it can be formed during the storage of crops.
Ochratoxin A causes a number of toxic effects in animal species. The most sensitive and notable effect is kidney damage. It may also have effects on fetal development and on the immune system.
Patulin is a mycotoxin produced by a variety of moulds, particularly Aspergillus and Penicillium. Although patulin can occur in various mouldy fruits, grains and other foods, the major sources of contamination are apples and apple products. The main cause of patulin is the blue mould P. expansum. Patulin is destroyed by the fermentation process, and so is much less prevalent in apple beverages, such as cider.
Patulin has been shown to have various toxic effects and can harm the immune system and gastrointestinal tract.
Fusarium fungi are common to the soil and produce a range of different toxins, including trichothecenes such as deoxynivalenol (DON), nivalenol (NIV) and T-2 and HT-2 toxins, as well as zearalenone (ZON or ZEA) and fumonisins. The formation of the moulds and subsequent toxins occur on a variety of different cereal crops. Different fusarium toxins can be associated more with certain types of cereal. For example, both DON and ZON may be associated with wheat, T-2 and HT-2 toxins with oats, and fumonisins with maize (corn).
Trichothecenes can be acutely toxic to humans, causing sickness and diarrhoea, but at much higher levels than those typically seen in the UK. Reported chronic effects in animals include suppression of the immune system. ZON is oestrogenic and has been shown to exhibit hormonal effects, such as infertility, particularly in pigs. Fumonisins have been related to oesophageal cancer in humans, and to liver and kidney toxicity in animals.
Other fusarium toxins have also been identified, such as moniliformin, beauvericin and enniatins. Although these are less well known, further studies and data-gathering exercises will help to evaluate any potential health effects.
These mycotoxins are produced by fungi of all species of the Claviceps genus, most notably by C. purpurea, which parasitise the seed heads of living plants (mostly cereals and grasses) at the time of flowering. The fungus replaces the developing grain or seed with a wintering body, known as ergot, ergot body or sclerotium. Ergot is ubiquitous, but is more common in seasons with heavy rainfall and wet soils. Rye and triticale are the most susceptible species because they have open florets.
The sclerotia are harvested together with the cereals or grass and can lead to contamination of cereal-based food and feed products with ergot alkaloids, particularly when they break apart. Normally, ergot is easily visible as intact sclerotia. Effective cleaning techniques at the mills can be employed to enable the removal of ergot sclerotia from grain at entry and before it goes for processing. Contamination of food for human consumption is not generally a problem.
Typical symptoms of ergotism are gangrene and/or hallucinations and convulsions. At lower levels of contamination they can cause vasoconstriction and reproductive effects.
The six most prevalent ergot alkaloids are ergotamine, ergocornine, ergocristine, ergocryptine, ergosine and ergometrine along with their –inine stereoisomers.
Alternaria is a genus of fungi that can contaminate crops such as fruits, vegetables, nuts and grains, and produce a range of mycotoxins, the alternaria toxins, including alternariol (AOH), alternariol methyl ether (AME), tentoxin (TEN) and tenuazonic acids (TeA). AOH and AME are considered as carcinogens, whereas AME, TeA and altertoxins (ATX) are fetotoxic and teratogenic in rats.
In addition, it has been suggested that in certain areas in China alternaria toxins might be responsible for oesophageal cancer.
There are some other mycotoxins that may potentially be of relevance to consumer safety, such as sterigmatocystin, cyclopiazonic acid, citrinin.
However, the incidence of such mycotoxins in foods has generally been found to be low and the potential for human exposure appears to be relatively limited. The Food Standards Agency, together with the European Commission and other member states, carries out and monitors the development of research and surveillance on such mycotoxins and evaluates the potential need for regulation as new information comes to light.