About mycotoxins

Aflatoxins are produced by the Aspergillus species of fungi mainly A. flavus, and A. parasiticus. The occurrence of these species and subsequent production and contamination with aflatoxins, are commonly associated with products from warm and humid climates. However, as such commodities are exported world-wide, contamination is of concern to importing countries including the UK. 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 toxin can also be found in the milk of animals which are fed contaminated feed, in the form of aflatoxin M1.

Aflatoxins, and in particular aflatoxin B1, are considered to be genotoxic and carcinogenic and there is evidence that they can cause liver cancer in humans. In accordance with expert scientific panels, including the European Food Safety Authority (EFSA), it is not possible to identify an intake without risk, for example a tolerable daily intake. Therefore, the limits set for certain foodstuffs for direct human consumption represent those that are considered to be as low as reasonably achievable (ALARA). There are higher limits for unprocessed commodities in recognition that processing and sorting can reduce the levels of aflatoxin contamination in consignments of certain commodities, for example, nuts.

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 also common in temperate climates, including the UK, where it can be formed in grain during storage.

Ochratoxin A causes a number of toxic effects in animal species, the most sensitive and notable effects being kidney damage. It may also have effect on foetal development and on the immune system. Scientific experts have determined that there is inadequate evidence that ochratoxin A causes cancer in humans. An evaluation by EFSA in 2006 derived a Tolerable Weekly Intake (TWI) of 120 nanograms (ng)/ kg bw.

Maximum limits are set in EC legislation for ochratoxin A in a variety of foodstuffs that contribute significantly to exposure but also include foods for infants and young children, as is the case for other mycotoxins, to protect vulnerable groups. As stored grain can be susceptible to ochratoxin A contamination, the Agency has produced a code of practice to assist producers to minimise ochratoxin A contamination in cereals.

Patulin is a mycotoxin produced by a variety of moulds, particularly Aspergillus and Penicillium. Although patulin can occur in many 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, the growth of which is encouraged by high humidity although the mould can also grow at low temperatures. Controlled or modified atmosphere storage can suppress blue mould growth, which is also visible and so is easily identified.

Patulin has been shown to have various toxic effects and can harm the immune system and gastrointestinal tract. The Joint FAO/ WHO Expert Committee on Food Additives (JECFA) established a Provisional Maximum Tolerable Daily Intake of 0.4 µg/kg bw (body weight), which was endorsed by the European Scientific Committee on Food (SCF) in 2000. An exposure assessment of patulin by the population of EU Member States was completed in 2003 (SCOOP 2003). It was concluded from the assessment that the average exposure is below the PMTDI of 0.4 μg/kg bw.

Maximum limits for patulin are set for apple juice and other fruit juices as well as solid apple products, including apple compote for infants and young children. The European Commission has produced a code of practice for the reduction and prevention of patulin contamination in apple juice and apple juice ingredients in other beverages. This is in order to encourage industry to adopt good manufacturing practices to reduce patulin contamination.

A variety of Fusarium fungi that are common to the soil produce a range of different toxins including trichothecenes such as deoxynivalenol (DON), nivalenol (NIV) and T-2 and HT-2 toxins as well as fumonisins and zearalenone (ZON or ZEA). The formation of the moulds and subsequent toxins occur on a variety of different cereal crops and can occur in northern, more temperate climates, including the UK. 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), especially in warmer climates in Europe and other parts of the world. Various factors affect Fusarium toxin formation including the amount of rainfall and moisture during the growing season and harvest.

As with most mycotoxins, Fusarium toxins are chemically stable, survive food processing stages and may pose a potential risk to human health as well as livestock. 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, particularly in pigs. Fumonisins are observed primarily on maize and in maize-based products and have been shown to affect the central nervous system of horses. In areas of the world where maize is part of the staple diet, fumonisin contamination has been linked to oesophageal cancer in humans, although there is currently inadequate evidence to classify fumonisins as carcinogenic in humans.

The toxicity and potential impact on human health of several of the Fusarium toxins has been appraised by the SCF and consequently there are various TDIs set for each of the Fusarium toxins mentioned above.

In 2003 the EC completed a SCOOP task, which involved collection of occurrence data on Fusarium toxins in food and assessment of dietary intakes by the population of the EU Member States. The information was used to inform the setting of maximum limits for Fusarium toxins, which were introduced in 2006 and applied from 2007. The limits apply to a range of raw cereals and cereal-based products such as bread, pasta, breakfast cereals, biscuits, snacks and cereal-based foods for infants and young children.

As Fusarium mycotoxins are produced in the field, Good Agricultural Practice is the primary mechanism to reduce Fusarium mycotoxins entering the food chain. The European Commission has published a Recommendation on the prevention and reduction of Fusarium toxins in cereals and cereal products (Commission Recommendation 2006/583/EC). Consequently. the Agency has developed a UK specific code of practice, which takes into account the principles detailed in the Commission’s Recommendation and is available to assist farmers and producers to minimise Fusarium contamination in cereals in the UK.

Fungi of the genus Alternaria are common pathogens of food crops. Alternaria species require relatively high moisture content for growth and are therefore common in fruits such as tomatoes, melons, apples, grapes and olives, causing moulding and rotting, either separately or in association with other fungi. This can occur at the start of harvest time and continue during handling and storage. Fruit imperfection, over-ripening, cold stress and surface physical damage are all factors that promote Alternaria infection.

A. alternata produces many mycotoxins including alternariol (AOH) and alternariol monomethyl ether (AME). Both of these are toxic to bacterial and mammalian cell lines. Other toxic effects have been seen in different species of animals and there is some evidence of synergistic effects of multiple Alternaria toxins. There are currently no statutory or guideline limits set for Alternaria mycotoxins in the EU as their natural occurrence in food appears to be low; a survey of apple products published by the Agency in 2003 showed only low levels of alternariol in just two samples. However, data on effects and exposure in humans is limited and new information will evolve to enable a better appraisal of risk to consumers.

Consumers should not eat visibly mouldy foods and should dispose of them. It is also important to ensure that damaged and visibly mouldy produce is not used in production.

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.

The sclerotia are harvested together with the cereals or grass and can thus 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 and in general there is a zero tolerance towards the presence of ergot in cereals. 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 therefore not generally a problem.

Sclerotia show significant differences in their total alkaloid content, as well as large differences in the patterns of alkaloids produced, that are determined by the individual fungal strain in a geographical region and the host plant. Ergovaline and ergovalinine are the most predominant toxins although other alkaloids may also be seen such as ergine, erginine and the clavinet alkaloids; however, these are less toxic to mammalian species. Livestock may be affected by ergot alkaloid poisoning, in particular lolitrems, including lolitrem B for example, following ingestion of contaminated ryegrass.