Mycotoxins, the invisible evil. THE ABC’S

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A serious risk to food chemical safety is mycotoxins, agricultural contaminants produced in some contexts (agriculture and storage) on grains and derivatives, milk, baby and infant foods, nuts and peanuts, coffee and cocoa, apples, wine and beer, spices and licorice. The strict limits of contamination allowed in individual product categories, defined by the European legislature, are subject to special control plans. Supply chain representatives, in synergy with health authorities, have developed best practices aimed at mitigating risks. Recurrent notifications in the European Rapid Alert System on Food & Feed(RASFF), however, confirm the topicality of the problem. ABC to follow

A ubiquitous enemy

Mycotoxins are toxic substances produced by the secondary metabolism of some fungi or molds (Aspergillus, Penicillium, Fusarium, Stachybotrys, Cephalosporium etc.). They occur naturally in plants and proliferate in environmental conditions favorable to them. The application of good agricultural practices, and in subsequent storage stages, is essential to mitigate risks.

The toxicity of mycotoxins is dose-dependent and occurs in both the short- and long-term. Cases of acute human toxicity, rare in Europe, have occurred several times in Africa from maize with high levels of aflatoxin contamination. Recall in this regard the crisis that occurred in Kenya in 2004, with 317 people affected by symptoms (hemorrhage, edema, acute liver damage) attributable to aflatoxicosis and 125 deaths.

Chronic exposure-prolonged intake of small doses of mycotoxins-is itself a cause of serious harm to human health. In fact, these toxins damage cellular structures, thus organs and systems, promote tumor formation, and weaken the immune system.

Mycotoxins, the legal limits

Limits to mycotoxins in food are set by reg. EC 1881/06, which has been updated several times. The values set for each toxin vary depending on the contribution of various foods to the diet, based on average levels of consumption of those foods. Also taking into account the Tolerable Daily Intake(TDI) threshold, expressed as nanograms of contaminant per kg body weight (ng/kg pc).

Higher values are allowed for food lots intended for sorting or physical treatment (e.g., brushing, sorting by optical systems for color or particle size). Those responsible for using and placing food on the market must in all cases ensure compliance with the limits specified for human consumption.

A serious flaw in the system of rules relates to the protection of children. Reduced limits of mycotoxin contamination are in fact provided only for foods intended for infants (up to one year of age) and early childhood (up to three years of age). Children over the age of 3 are actually equated with adults, although their weight is considerably less. Resulting in mycotoxin exposure of a magnitude, in some cases, well above the tolerable daily toxicological thresholds that have been assessed on adult individuals.

Aflatoxins, the black beast

The most dangerous mycotoxins are aflatoxins. They are genotoxic, hepatocarcinogenic, and toxic to the immune system. Those with the highest prevalence and toxicity are five. The most alarming is B1, since 1993 classified by the International Agency for Research on Cancer (AIRC) in Group 1 as a ‘human carcinogen.’

Also under special observation are aflatoxins B2, G1, G2 and M1. The latter results from the metabolism of aflatoxin B1 by animals fed contaminated feed (by B1). The food at greatest risk of contamination is milk, for which there is a maximum level of 0.050 μg/kg, halved (to 0.025) for baby food. The toxin is distributed in cheeses in relation to specific milk-to-cheese conversion values.

The foods at greatest risk of aflatoxin contamination are corn, nuts and dried fruits, spices, and milk (the latter for M1 alone). Below are the statutory limits for various foods, expressed in micrograms per kg (μg/kg).

Europe’s shield against toxic invasion

The European RASFF system, in the first half of May 2019 alone, recorded some 30 alerts on food contaminated with mycotoxins. Almost always from aflatoxins, on goods arriving from the same countries. Primarily from the US, where levels of contamination 10 times higher than in Europe (!) are tolerated in some cases. A systemic threat to the health of the European population, in spite of the false promises of food safety guarantees by supporters of CETA and TTIP.

Consignments flagged through RASFF are almost always blocked before they are released into the EU. Moreover, there is no shortage of alerts with public recalls, on products already placed on the market.

This is the case of nutmeg packaged in Poland with raw material from Indonesia, distributed in several member states by a German-based operator. Intercepted by authorities in the Czech Republic, it was found to be contaminated with 67.6 ppb of ochratoxin A.

Ochratoxin A, the number 2

Cereals and baked goods (made from wheat, barley, corn, oats), raisins, coffee, cocoa, spices, licorice, pork products, wine, and beer are the foods at risk of ochratoxin A contamination. Classified in 1993 as a potential carcinogen by AIRC (the International Agency for Research on Cancer), which placed it in Group 2B (possible human carcinogen), it has toxic effects that include nephrotoxicity, liver damage, enteritis, teratogenesis, and kidney carcinogenicity.

The wide consumption of these foods exponentially increases the risk to the most vulnerable population, including children. The European Food Safety Authority (EFSA), in its 2006 opinion, established a tolerable weekly intake of 120 ng/kg body weight.

The limits of ochratoxin A (OTA) allowed on foods are very stringent, as the table below shows. Two foods are exceptions, which deserve mention:
– Soluble coffee, with a threshold twice that of roasted coffee,
– Licorice, as such or as a food ingredient, in drinks and candies.

Patulin, the toxin in apples

Fruit juices, even reconstituted ones, nectars, and fruit compotes are the foods in which patulin, a mycotoxin suspected of carcinogenicity and which at high doses causes brain, gastric, and pulmonary hemorrhages, is developed.

The limits of patulin contamination are as follows:
– 50 micrograms per kg in fruit juices, nectars and alcoholic beverages made from apple, such as cider,
– 25 μg/kg in products containing apples in solid state, including apple compote and apple puree, where intended for direct consumption,
– 10 μg/kg in foods for infants and young children.

Zearalenone, lurking in corn.

A contaminant of corn (or maize) and other grains, zearalenone (ZEA) is a ‘mycoestrogen’ and causes symptomatology observed in farm animals, manifesting in infertility and reduced milk production.

The legal limits are higher for foods made from corn (the cereal of choice for celiacs), as the table shows. The maximum tolerable level is set at 400 micrograms/kg, while the daily toxicological threshold has been set at 0.25 micrograms per kg body weight.

Don, the mycotoxin in durum wheat and pasta.

Deoxynivalenol (DON), also known as vomitoxin, is often cited as an indicator of grain quality, especially when imported. It is a widespread toxin in food and has toxic effects that manifest themselves in, among other things, nausea, vomiting, gastrointestinal disorders, and headache. The maximum daily intake is 1 µg/kg body weight.

The legal limits in µg/kg are as follows:

– Cereal flour, bran and germ, dry pasta 750
– Breads, pastries, cookies, snacks and breakfast cereals 500
– Food intended for infants and young children 200
– Unprocessed durum wheat, oats and corn 1750
– Other unprocessed grains 1250

More dangerous are other mycotoxins in the trichothecene group, the same group to which DON belongs, which are found in wheat, barley, oats, rye and corn. The one with the most pronounced toxic properties is T-2, followed by DAS and NIV. The maximum daily intake is set at 0.02 µg/kg body weight for T-2 and HT-2 toxin and 1.2 µg/kg body weight for NIV. No residues are allowed in food.

Fumonisins in corn

Fumonisins are produced by fungi of the genus Fusarium. The ‘target’ cereal is corn, but they are also found in sorghum and cocoa, as well as in beer. The most toxic fumonisin is B1, classified by AIRC in 1993 as Group 2B, meaning possible human carcinogen. It is suspected of promoting the occurrence of esophageal cancer.

The maximum daily exposure level for fumonisins is 2 μg/kg body weight. The legal limits refer to the sum of fumonisins B1 and B2 and are as follows (in μg/kg)
– Unprocessed corn 4000
– Corn and corn products 1000
– Corn-based breakfast and snack cereals 800
– Food intended for infants and young children 200.

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Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".