How can we manage mycotoxins in the supply chain?

Published on 28 September 2015

Author: Rebecca Carter

Mycotoxins, produced by fungi, are a health risk within the food supply chain. Levels are related to fungal development during crop growth and storage, which is influenced by environmental conditions such as temperature and moisture. Mycotoxins are not completely removed by processing and, if ingested, can cause harm to human and animal health and in extreme cases, even death. Common sources of mycotoxins include cereals, nuts, coffee and fruit. There are legal limits set in human and livestock diets but exceedances can and do occur, both in raw materials and in processed food and feedstuffs. This article explains the key issues and explores how we can address the problem.

What are mycotoxins & how are they regulated?

Mycotoxins are a group of naturally occurring chemicals produced by certain fungi. The mycotoxins of most concern from a food safety perspective include the aflatoxins (B1, B2, G1, G2 and M1), ochratoxin A, patulin and toxins produced by Fusarium, including fumonisins (B1, B2 and B3), trichothecenes (principally nivalenol, deoxynivalenol, T-2 and HT-2 toxin) and zearalenone.

The presence of mycotoxins in food for human consumption is regulated under EC Union Regulation 1881/2006 which sets out legal permitted maximum levels (μg/kg) of certain mycotoxins in foodstuffs. For deoxynivalenol (DON), one of the more commonly detected mycotoxins in cereals, the limit is set at a maximum of 1250 µg/kg in unprocessed cereals (apart from Durum wheat), 750 µg/kg in pasta and 500 µg/kg in bread and breakfast cereals. In addition to cereals, mycotoxins are present in a number of other raw materials that enter the food supply chain such as groundnuts (peanuts), tree nuts, oilseeds, dried fruits, spices, coffee, wine, apple juice and milk.

Fresh produce can also contain mycotoxins, with the mycotoxin patulin found in certain types of fresh produce such as apples, sweet peppers, soft red fruit and tomatoes, particularly when the fruit is not stored correctly post harvesting. In the EU, the legal limit for patulin is 50 ug/kg for fruit juices and 10ug/kg for infant juices.  Patulin is very stable in fruit juices because the presence of sucrose within the juice protects patulin from degradation during heat treatments.  Recent research has found that 50% of apple juice samples tested from eight different trademarks and different batches for the same trademarks exceeded the maximum legal levels of patulin, with some samples having patulin levels above 100 ug/kg.

Mycotoxins are also regulated in animal feed. In livestock, the presence of undesirable substances (chemical contaminants) in feed is controlled by EC Directive 2002/32, which sets maximum permitted levels (MPLs) for aflatoxin B1 at 0.02mg/kg (ppm) for all feedstuffs with a moisture content of 12%. Guidance values have also been set for five mycotoxins (deoxynivalenol, zearalenone, ochratoxin A and fumonisins B1 and B2) under Commission Recommendation 2006/576/EC, with lower guidance levels for pigs and young animals who are thought to be more susceptible to the effects of mycotoxins.

What are the impacts of mycotoxins?

Health impacts- Mycotoxins are a significant risk to food supply chains as they cannot be fully removed from raw food materials and so can be carried through into processed foods, where they pose a health risk, even at low concentrations. In humans, mycotoxins have been linked to certain types of cancer, kidney damage, gastrointestinal disturbances and reproductive disorders.  There arewell documented cases of ingestion of mycotoxins causing a risk to human health; for example in 1998, consumption of aflatoxin–contaminated ground nut cake called 'kulikuli' in south western Nigeria was linked to child death and in 2004 maize contaminated with aflatoxins was implicated in 125 deaths in Kenya, with aflatoxin B1 levels as high as 4,400 parts per billion (ppb), 220 times higher than the Kenyan regulatory limit for food. 

In the UK, however, risk of mycotoxins contamination is generally low.  For example, results from anEFSA study found that DON levels exceeded legal limits in 2% of 26,613 samples tested between 2007-2009 and the mycotoxin Sterigmatocystin, which is structurally related to aflatoxin B1 and can occur in grains and grain based products, was found to be present at levels below legal limits in almost all of 1,259 samples tested, except from one sample of oats. Mycotoxin levels can vary massively depending on season specific factors, storage conditions and source.  The risk of mycotoxin levels exceeding legal limits in unprocessed cereals are increased in wet harvest years.  In 2008, zearalenone (ZON) levels of a significant number of unprocessed grain samples exceeded legal limits (1000ppb) in the UK due to wet conditions during harvest.

Animal performance- Mycotoxins can also effect animal performance; in dairy cows, ingestion of mycotoxins has been shown to decrease daily milk yields by 2-3 litres/cow, lower milk quality and reduce fertility.  In pigs, ingestion of aflatoxin at a concentration of 20- 200 ppb has been found to decrease feed intake and growth performance, and at higher levels (1,000 to 5,000 ppb) has been known to lead to acute effects, including death.

Business Impacts

Costs of testing - To reduce the risk of mycotoxins causing human or livestock health issues and to meet compliance requirements, food and feed business operators carry out regular mycotoxin tests. In the UK, this can be done at an external United Kingdom Accreditation Services (UKAS) accredited laboratory or for certain mycotoxins using rapid on-site tests. Mycotoxin testing can cost around £30-40 per test by ELISA and as such it can be very costly for businesses, particularly in seasons where mycotoxins are predicted to be at high risk. Other food system controls include the Combinable Crop Passport, which has to be submitted with each load of grain. This details key information about that load including variety, post-harvest treatment, results of any mycotoxin tests and for wheat, results of the AHDB mycotoxin risk assessment.

Managing raw material rejections - Presence of mycotoxins at levels above legal limits can cause products to be rejected at intake. In the UK food business operators have a legal responsibility under Article 19 of Regulation (EC) No 178/2002 to report any food imported, produced, processed, manufactured or distributed that they suspect may not comply with food safety requirements to the Food Standards Agency (FSA). If mycotoxin levels are found to exceed legal limits there are options available for the affected foodstuff such as further processing, diversion to animal feed or re-export but these are dependent on the degree to which the levels exceed the legal maximums set and, in some cases, the affected lot of food may have to be destroyed.

Product withdrawal and reputational damage - Due to the controls in place within the food supply chain, the presence of mycotoxins within food at levels which could affect human health is extremely rare, however, there are some suspected cases where mycotoxins have been suggested to be linked to human health risk, even at levels below legal maximums. For example, between 1997 to 1998, approximately 1,700 US children became ill with vomiting, nausea, headache and abdominal cramps linked to eating burritos containing wheat flour. Although levels of DON in the burritos were less than 1 ppm, the Food and Drug Administration (FDA) advisory level, DON could not be eliminated as the causal agent because this advisory level is set for adults and may not be applicable to children. This outbreak affected the reputation of the companies involved and led to approximately £2 million of costs in associated product recalls.