Scientific and regulatory developments in relation to mycotoxins in Australia and internationally

By Rozita Spirovska Vaskoska, MSc (Food Safety), BSc (Food Technology), FoodLegal Scientist and Joe Lederman (FoodLegal Co-Principal)

© Lawmedia Pty Ltd, October 2020

This article reviews the current status of the scientific findings on mycotoxins and their health effects for consumers of different foods, as well as discussing more recent findings on new and emerging mycotoxins and new analytical testing methods; and considers the regulatory framework for mycotoxins in the Codex Alimentarius as well as the regulatory deficiencies in this area not only in the Australia New Zealand Food Standards Code but also other regulatory aspects such as cereal and other production systems and the need for better uniform standards and regulations throughout Australia.

Mycotoxins are a class of toxins produced by filamentous fungi (moulds) as secondary metabolites, which are often found to contaminate plant-based food and feed, and to end up in the food chain though the feed chain (i.e. in the case of milk). Secondary metabolites mean that they do not have an apparent function and are produced when the fungus is mature [1].

Mycotoxins are naturally present in the feed and food chain, with mycotoxin occurrences already high and becoming more frequent on a global basis. The extent of their occurrence has been apparent in global surveys that have included Australia in their studies. For example, as far back as 2004, a survey showed occurrences of the following mycotoxins in the following proportions of surveyed in feed and feed raw material in the Oceania region [2]:

·         7 aflatoxin

·         20 zearalenone

·         34 deoxynivalenol (DON)

·         10 fumonisins

·         12% ochratoxin A

In relation to food, a small 2012 study on corn samples in Oceania has shown the presence of common mycotoxins in the range of 9-64% positive of the samples studied [3]. The weather conditions in the agricultural south-eastern part of Australia have been found to be amenable to the occurrence of fumonisnis as myxotoxins in Australian feed [2].

Extensive research has been undertaken into these compounds in the past, and this did result in at least some types of mycotoxins becoming regulated in many countries. However, new scientific findings have emerged and it is apparent that food safety laws and supply chain standards have not kept up with these developments.

Types of mycotoxins and their effect on human health

There are eight major groups of mycotoxins that are well researched:

·         Aflatoxins;

·         Fumonisins;

·         Trichothecenes;

·         Zearalenone;

·         Citrinin;

·         Patulin;

·         Ergot alkaloids; and

·         Ochratoxin A.

Alfatoxins

Aflatoxins are by far the most well-known category of mycotoxins [4], and they are produced by the mould called Aspergillus. There are several types of aflatoxins distinguishable by heir characteristics (fluorescence and mobility during liquid chromatography). They can naturally contaminate cereals, seeds, nuts and spices. Aflatoxins in humans can decrease the cell immunity, contribute to the risk of liver cancer and are a known risk factor for hepatocellular cancer [1, 5]. Aflatoxins have been shown to be present in a metabolized form in the milk from animals that have consumed contaminated feed [6].

Fumonisins

Fumonisins are produced by the mould Fusarium and are also a large group of chemically similar compounds. They have been found in corn, and they are associated with oesophageal cancer in human and a range of conditions in animals [7].

Trichothecenes

Trichothecenes can be produced by more than seven types of moulds, and are a very large group of compounds. The most significant and best characterized mycotoxins from this group are deoxynivalenol (DON), nivalenol (NIV), toxin T2 and HT2. DON is found in safflower seed, barley, rye, and wheat and have also been shown to cause gastrointestinal symptoms in animals [1].

Citrinin

Citrinin comes from Penicillium citrinum mainly, and it can be found in cereals and cereal products, rice, pomaceous fruits (e.g., apples), fruit juices, black olives, roasted nuts (e.g. almonds, peanuts, hazelnuts, pistachio nuts), sunflower seeds, spices (e.g. turmeric, coriander, fennel, black pepper, cardamom and cumin), cheese, sake, red pigments and other food supplements [8]. It mainly causes symptoms in the kidneys.

Patulin

Patulin is produced by Penicilium, Aspergilus and Byssochlamys species of moulds, and it known for forming a blue mould on apples and other fruits [9]. Patulin is a very interesting mycotoxins, since early research encouraged its usage as an antimicrobial, until its toxicity was recognised. While its toxicity has not been completely clarified in terms of the effect on human health, the fact it can be found in fruit juices such as apple juice, means that the potential exposure could be high.

Ergot alkaloids

Ergot alkaloids are produced by Claviceps purpurea moulds, and they cause very severe diseases (gangrenous and convulsive), known since the Middle Ages as `Holy Fire` caused by eating bread from contaminated cereals [1]. These compounds are thermolabile and were believed to have been eliminated from human food, but not from animal feed [1].

Ochratoxin A

Ochratoxin A is a product of Aspergillus ochraceus, and it is found in oats, barley, wheat, coffee grains and other foods [1]. It can cause toxic effects on the kidneys and liver, and cause cancer, immunosuppression and teratogenic effects (i.e. effects on the human embryo) [1].

Categorisation and new and emerging mycotoxins

Contemporary scientific findings have emerged from studies of the mainstream types of mycotoxins to show that the health risks extend beyond these specific compounds and that there is additional risk from so-called ‘masked mycotoxins’.

A German study has defined three main groups of mycotoxins, in which the well-known mycotoxins (known as ‘free mycotoxins’) were more easily detected in food. Next to this, they distinguish a group called ‘matrix associated’ mycotoxins that form complexes with the food matrix or are physically trapped, dissolved or bound by covalent bonds [10].

Finally, they define a third chemically or biologically modified group of mycotoxins, which appears to be very important as they may be undetected if not analysed properly. For example,  a biological modification can result in a binding to human DNA that becomes toxic, and a major danger to human health. A good example is the chemical modification causing toxicity upon Maillard reaction between sugars and mycotoxin or formation upon digestion [10].

While it might appear that a lot is known around mycotoxins already, many emerging mycotoxins are still the subject of current ongoing research. An Austrian study looked into newly discovered types of mycotoxins that might have the potential of causing adverse health effects and still needs further research [11]. The Austrian study reviewed the following compounds: enniatins, beauvericin, moniliformin, fusaproliferin, fusaric acid, culmorin, butenolide, sterigmatocystin, emodin, mycophenolic acid, alternariol, alternariol monomethyl ether, and tenuazonic acid [11]. Whilst the study found that alternariol monomethyl ether, mycophenolic acid and culmorin are of less concern, significant research gaps have been identified for most of these compounds.

Scientific detection methodologies for mycotoxins

Testing methods for mycotoxin presence and quantification include chromatographic techniques and immunoassays such as ELISA [12]. However, new research approaches show the need to develop better processes of detection and more practical solutions for applications by industry. A good example of a simplified testing solution has been the usage of biosensors [13] and also matrices for associated mycotoxins. However, the health risk demands further work and testing systems to be given high priority.

The need for prevention and detoxification strategies in the food chain

The presence of mycotoxins is more than a serious economic problem, given that it is really a human health and public safety issue. It is essential therefore for real prevention and detoxification strategies to be implemented. At an international standard-setting level, the Codex Alimentarius has proposed some codes of practice for strategies to prevent the formation of mycotoxins. For example, Code of Practice CXS 78-2017 recommends practices in the prevention and reduction of mycotoxins in spices. Prevention seems to the most important step and therefore farming education and training are critical to reduce the impact. In some African countries, this has been shown to be more effective than regulatory sanction in reducing mycotoxin contamination occurrence [14]. However, the need for regulation should not be subverted by delegating the whole task to educators.

Alternatively, detoxification of mycotoxins can be done by physical (hand sorting, screening, density separation etc.), chemical [5] or biological methods [14]. Some microorganisms such as lactic acid bacteria and yeasts have also been found to be effective in detoxifying some of these compounds [15].

International standards: Codex Alimentarius

General Standard CXS 193-1995 for contaminants and toxins in food and feed of the Codex Alimentarius recommends a detailed regulatory framework for mycotoxins, specifically: total aflatoxins, aflatoxin M1, deoxynivalenol (DON), fumonisins, ochratoxin A and patulin. Maximum level (ML), detailed sampling plans and analytical methods are recommended for these mycotoxins. MLs are established for aflatoxins in almonds, brazil nuts, hazelnuts, peanuts, pistachios and dried figs. MLs are also established for: Aflatoxin M1 in milk; for DON in celeral based foods for infants and young children, flour, meal semolina and flakes from wheat, maize and barley and cereal greains (wheat, maize and barley) destined for further processing; fumonsins B1 + B2 for raw maize grain and maize flour and maize meal; ochratoxin A in wheat, barley and rye; and patulin in apple juice.

The need for better Australian regulation for aflatoxins in food and feed supply chains

In Australia (as at October 2020), mycotoxins are still less regulated than what has been proposed as the standards of the Codex Alimentarius. To date, Australian governments at federal and state levels are relying on a risk-based approach to detection, rather than ongoing monitoring, testing and studies of the health impacts. The failure to maintain any inspection-based approach ignores the potential public health safety risk. Governments are merely passing on the responsibility to the anonymity of production systems [16], which therefore does not allow for accountability and transparency.

Standard 1.4.1. and Schedule 19 regulate the presence of aflatoxin in peanuts and tree nuts, ergot in cereal grains and phomopsins in lupin seeds and products of lupin seeds. The levels for aflatoxins in Australia for peanuts and tree nuts are recommended to be a maximum of 0.015 mg/kg which coincides with higher limit in Codex Alimentarius for these specific aflatoxins that for the different categories of nuts is set between 0.01 – 0.015 mg/kg.

However, the lack of Australian regulation or further regulation internationally for most mycotoxins and types of food is not uniform. A food producer in Australia may still face stricter and more expensive regulations being applied either by laws or standards or contractual obligations in a destination country. An industry itself may have set its own standards [17, 18].

If no other regulatory or industry standard is in place, one might expect that general risk mitigation principles would still require the producer to keep mycotoxin levels at safe minimum levels – as low as reasonably achievable (ALARA principle).

Conclusion

Mycotoxins are natural toxins in food, and they can be found in many chemical forms, as well as in free, associated or modified conditions. Regulation is an important strategy for controlling mycotoxins, but such regulation should be developed in line with the latest scientific findings in relation to health effects and new scientific developments for identification and suitable detection and testing. To date (as at October 2020), Australia is well behind and is failing its duties to its own food consumers by the standards of Codex Alimentarius. Furthermore, better prevention strategies are a critical essential imperative for achieving a lower presence of  mycotoxins in the food chain.

References

1.         da Rocha, M.E.B., et al., Mycotoxins and their effects on human and animal health. Food Control, 2014. 36(1): p. 159-165.

2.         Schatzmayr, G. and E. Streit, Global occurrence of mycotoxins in the food and feed chain: facts and figures. World Mycotoxin Journal, 2013. 6(3): p. 213-222.

3.         Rodrigues, I. and K. Naehrer, A three-year survey on the worldwide occurrence of mycotoxins in feedstuffs and feed. Toxins, 2012. 4(9): p. 663-675.

4.         Chu, F.S., Mycotoxins: food contamination, mechanism, carcinogenic potential and preventive measures. Mutation Research/Genetic Toxicology, 1991. 259(3-4): p. 291-306.

5.         Leung, M.C.K., G. Díaz-Llano, and T.K. Smith, Mycotoxins in Pet Food:  A Review on worldwide prevalence and preventative strategies. Journal of Agricultural and Food Chemistry, 2006. 54(26): p. 9623-9635.

6.         Serraino, A., et al., Occurrence of aflatoxin M1 in raw milk marketed in Italy: Exposure assessment and risk characterization. Frontiers in Microbiology, 2019. 10(2516).

7.         Scott, P.M., Fumonisins. International Journal of Food Microbiology, 1993. 18(4): p. 257-270.

8.         de Oliveira Filho, J.W.G., et al., A comprehensive review on biological properties of citrinin. Food and Chemical Toxicology, 2017. 110: p. 130-141.

9.         Diao, E., et al., Removing and detoxifying methods of patulin: A review. Trends in Food Science & Technology, 2018. 81: p. 139-145.

10.       Rychlik, M., et al., Proposal of a comprehensive definition of modified and other forms of mycotoxins including “masked” mycotoxins. Mycotoxin Research, 2014. 30(4): p. 197-205.

11.       Gruber-Dorninger, C., et al., Emerging mycotoxins: beyond traditionally determined food contaminants. Journal of Agricultural and Food Chemistry, 2017. 65(33): p. 7052-7070.

12.       Pereira, V.L., J.O. Fernandes, and S.C. Cunha, Mycotoxins in cereals and related foodstuffs: A review on occurrence and recent methods of analysis. Trends in Food Science & Technology, 2014. 36(2): p. 96-136.

13.       Chauhan, R., et al., Recent advances in mycotoxins detection. Biosensors and Bioelectronics, 2016. 81: p. 532-545.

14.       Matumba, L., et al., Keeping mycotoxins away from the food: Does the existence of regulations have any impact in Africa? Critical Reviews in Food Science and Nutrition, 2017. 57(8): p. 1584-1592.

15.       Hathout, A.S. and S.E. Aly, Biological detoxification of mycotoxins: a review. Annals of Microbiology, 2014. 64(3): p. 905-919.

16.       Cressey, P., Mycotoxin risk management in New Zealand and Australian food. World Mycotoxin Journal, 2009. 2(2): p. 113-118.

17.       MAA. Market requirement information package. Available from: http://www.maizeaustralia.com.au/qualityspecs_files/2.%20MRIP%20-%20Mycotoxin%20Standards.pdf.

18.       Grain Growers. Available from: https://www.graingrowers.com.au/wp-content/uploads/2018/04/graingrowers_101805_safety-concerns_04.pdf.

 


This is general information rather than legal advice and is current as of 19 Oct 2020. We therefore recommend you seek legal advice for your particular circumstances if you want to rely on advice or information to be a basis for any commercial decision-making by you or your business.