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New IARC report urges action against widespread mycotoxin contamination in developing countries


In a new Report published by the International Agency for Research on Cancer (IARC), a Working Group of experts reviewed the health effects of aflatoxins and fumonisins. The panel concluded that these mycotoxins are not only a cause of acute poisoning and cancer but are also a likely contributor to the high levels of stunting in children in affected populations. Dr Christopher Wild, Director of IARC and an expert on aflatoxin carcinogenicity, explains what mycotoxins are.

Mycotoxins are actually produced by fungi that commonly grow on some of our dietary staple foods, particularly in the developing world, so crops such as maize (or corn) or peanuts, for example, are commonly contaminated by these different types of fungus that produce, in turn, the toxins. So we see very high levels of exposure to these potent toxins in sub-Saharan Africa, South-East Asia, parts of Latin America, where the conditions are right for the fungus to grow and produce the toxin. And the particular problem that we face in those regions is that people often consume a lot of those types of foods as part of their staple diet, so the combination of contamination with a high level of consumption leads to the very high exposures that we see in these regions.

What are their impacts on health?

Well, aflatoxins are well established to have a number of health impacts, and particularly where the high exposures are occurring in the developing countries. The problem there is that people eat the diet, such as maize or peanuts, which are heavily contaminated with these toxins. We see three main health effects, in fact. First of all, at very high levels we see acute poisoning and even deaths from aflatoxin contamination. The second thing is these toxins are well known to cause liver cancer, particularly in people that also have chronic infection with hepatitis B virus, which is commonly occurring in the same areas that we have heavy aflatoxin contamination. And more recently, and very strikingly, has been the observation that young children that consume high amounts of aflatoxin show evidence of stunting and growth impairment, and the concern is that that stunting and growth impairment makes the child more susceptible to other illnesses, such as infectious diseases, which cause this high level of mortality - childhood mortality - in many of these countries.

What are the key recommendations identified in the Working Group Report?

The first recommendation, really, is that we need to know a lot more about the level of exposure to these mycotoxins in the populations where they commonly occur. In fact, rather paradoxically, we have a lot more information about the levels of exposure in countries where these toxins are rare compared to those where they are common. So we really need to characterize the extent of exposure much better.

The second level of recommendation was about what can be done to combat the problem and, more specifically, three particular interventions that would be helpful. The first is difficult to achieve, but would help, is to diversify the diet so that people are not so reliant just on the crops which have heavy levels of contamination. The second is that it is possible to sort the crop and sort out the maize kernels - or the peanuts, for example - that have very high levels of contamination, because they show evidence of fungal damage. And the third is that because the fungus that produces aflatoxin grows in damp, humid conditions that we see in many storage facilities - in parts of sub-Saharan Africa, for example - we can actually improve the conditions of storage to impair the growth of the fungus and therefore the production of the toxin.

Are there any new technologies on the horizon?

There are new opportunities. The Working Group found that the sorting and the better post-harvest storage are already ready to go into practice. But there are new technologies, and particularly interesting is the identification of some strains of fungus that do not produce aflatoxin but are of the same family that does produce the toxin. And so early trials are showing, in fact, that you can compete in the field by spraying the fields with these non-aflatoxin-producing strains of fungus, and that those can reduce the presence of the other, dangerous fungal strains.

What would you like the outcome of the Report to be?

I think for me the outcome of this Report has to be to translate the scientific knowledge that we have into action, and practically intervene to reduce the level of this human exposure. These are dangerous toxins. We know there are adverse health effects. We have ways to change human exposure, but we're not applying them. So we hope that this Report will be useful for decision-makers, policy-makers in deciding on how to combat the aflatoxin problem in their own countries. At the moment we're facing, I would say, quite a shameful neglect of an important public health problem, and one that we have opportunities to redress.