IARC urges action against mycotoxin contamination in developing countries

By Joseph James Whitworth contact

- Last updated on GMT

Photo: Istock/Armin Staudt
Photo: Istock/Armin Staudt

Related tags: Mycotoxin

The problem of mycotoxin contamination in developing countries has been ‘ignored for too long’ and it is time to ‘turn science into action’, according to the director of an organisaton behind a report on the subject.

The International Agency for Research on Cancer (IARC) reviewed the health effects of aflatoxins and fumonisins.

An estimated 500 million of the poorest people in sub-Saharan Africa, Latin America, and Asia are exposed to the pervasive natural toxins, aflatoxins and fumonisins, by eating a staple diet of groundnuts, maize, and other cereals.

This contrasts with developed countries, where people and livestock are protected by good agricultural practices, regulation, and legislation.

Dr Christopher Wild, director of IARC, said he has worked in the area of aflatoxins since the 1980’s and IARC classified it as a cause of human liver cancer in 1987 so it’s not a new problem being highlighted.

“What we are highlighting are two new things: the first is the working group found strong evidence for the link to stunting in children and that could be a much greater health impact than even liver cancer,” ​he told FoodQualityNews.

“The second thing is we haven’t placed enough emphasis before on what can be done to combat the problem and that’s the bit that really needs to be highlighted, there are things that can be done and that are cost-effective.”

The work (read it in full here​) was supported by the Bill & Melinda Gates Foundation (BMGF).  

The panel concluded the mycotoxins are a cause of acute poisoning and cancer and a likely contributor to the high levels of stunting in children in affected populations.

Possible interventions

It evaluated 15 interventions against mycotoxins, considering the strength of the evidence as well as its completeness and transferability at an individual, community, or national level. Four were judged ready for implementation.

Intervention for which the strongest evidence of improvement of health exists, but which is also the most difficult to achieve, was to increase dietary diversity.

Other strategies deemed ready for implementation were sorting of the crop; a package of post-harvest measures, including improved storage; and, in Latin America for maize, optimized nixtamalization.

Of dietary diversity, Dr Wild said it has good examples but it is coming with economic development.

“So for example, there used to be parts of China with extremely high aflatoxin levels and liver cancer rates in Qidong County and what happened was as they developed economically the population shifted from consuming mainly maize, corn, to consuming more rice which is not as affected by aflatoxins so their level of exposure dropped dramatically and now the liver cancer rates are coming down.

“There are two things that were really strongly endorsed and can be applied in low income settings, the first is sorting the crop so visibly mouldy peanuts or maize kernels can be hand sorted and removed and that has been shown even at village level to reduce the level of contamination in food.

“The second is what we put as a package of post-harvest measures so making sure the crops are dried properly, stored in dry conditions and you stop the fungus growing and producing toxin during storage.

“The fourth one was a bit particular because it is about treating maize with an alkaline solution that is used in Latin America to make tortillas. [Nixtamalization] is a traditional way of preparing the corn-based tortillas and treating with this lime alkaline solution, it is not done deliberately to destroy aflatoxin but the chemical process actually does reduce levels markedly.”

Export good crop and keep lesser quality

Wild said it has seen countries exporting crops like peanuts to Europe and to meet the stringent import regulations on the level of aflatoxin in food, they have to export the very best quality crop.

“What happens then is the poorer quality foods can often be consumed locally and the better quality ones exported. Often even the exported food is only used for animal feed, so we have this paradoxical situation where a country may be exporting higher quality food for animal feed in the developed world and consuming the contaminated crops locally,” ​he said. 

“We think there is a double benefit of improving the quality of the food and controlling the toxin level, first it makes it better quality to be eaten and improves the health of the population locally but also it probably has an economic benefit for the country in terms of the value of its exports.”

In terms of reducing exposure, Dr Wild said the first thing to understand is they are produced by fungi that grow on crops so there can be three broad approaches.

“The first approach is to avoid the foods that are contaminated with these toxins but in many cases the food themselves are dietary staples for the population so that is quite difficult to achieve. The other two ways are to try and block the growth of the fungus and the production of the toxins either during the growth of the crop, so pre-harvest, or during the storage, post-harvest,” ​he said.

“In those two cases there are different ways to try and limit the production of the toxin, pre-harvest by ensuring that the crops are not stressed, that they are adequately irrigated and post-harvest is important for aflatoxin to ensure that the crops, when they are stored, are dried properly and maintained in conditions that don’t allow the fungus to grow.”

Dr Wild said there have been small kits like dipsticks developed predominately to check the level of contamination in foods with a view to a commercial market, so meeting the stringent levels of contamination that would be needed to export the crop.

“I think what’s needed is a rapid test that could tell us if we have dangerous levels of toxin in the food that is going to be consumed locally,” ​he said.

 “With aflatoxin we’ve had a number of poisoning outbreaks in Kenya for example, really high levels of aflatoxin and people had not much choice to eat that contaminated corn or maize. So if there were tests that could very quickly examine a suspicious crop we might be able to avoid some of the acute toxicity that we’ve seen in some conditions.

“But that needs a slightly different type of test than the one that is standardised for meeting the levels that are acceptable for international trade.”

To prioritise you need to know the scale of the problem, said Dr Wild.

“One thing I hope is there will be a number of countries who are affected by these toxins that decide to make a difference and change something in their agricultural practices, that come forward and request assistance to start to make a change,” ​he said.

“Within my own organisation in the WHO we try to highlight this topic more to the Member States to support them and explain what can be done.

“The third thing I’d like to see is to create some partnerships between governments, international organisations, NGOs and the private sector to put our heads together and see what is the best way to meet this challenge - that would be the most important on the prevention side.

“We still need to do some research to understand very clearly the burden of disease in young children linked to exposure to these toxins…just what affect it is having on young children in the developing world.”

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