My Oh My… Mycotoxins
Crops can be susceptible to fungal infections as they grow in the field, are harvested and are processed for the marketplace. Mycotoxins are poisonous chemicals produced by the growth of this fungi, especially in grain crops such as corn and sorghum, and if consumed, can lead to health problems. While there are hundreds of mycotoxins, aflatoxins, in particular, are of greater concern to public health and trade; spices are very prone to aflatoxins. Mycotoxins can cause diseases such as cancer and child stunting — and contaminated feed can cause health issues in farm animals.
We spoke to Ranajit Bandyopadhyay, a plant pathologist from the International Institute of Tropical Agriculture (IITA) and Ahmed Kablan from the U.S. Agency from International Development (USAID), two experts on the topic, to better understand how plant science innovations can reduce mycotoxins and aflatoxins and make our food supply safer.
What are mycotoxins and aflatoxins?
Bandyopadhyay — Mycotoxins are secondary metabolites of fungi that are toxic to humans and/or animals. That may sound a little scientific, but basically these are naturally occurring chemicals that fungi produce during the course of their growth. The toxin-producing fungi infect crops before they are harvested and continue to grow inside the plant. Aflatoxins are a type of mycotoxin and mostly affect grain crops in the tropics.
How do mycotoxins and aflatoxins get into our foods?
Bandyopadhyay — the crops are initially infected while they are in the field and the problem continues as the crop is harvested and stored, culminating when consumed by people and animals.
Do mycotoxins and aflatoxins impact food safety? Are they dangerous to consumers?
Bandyopadhyay — In large amounts, mycotoxins can have a negative impact on food safety. They can cause diseases like liver cancer or cause child stunting.
Kablan — Consumption of crops that are contaminated with aflatoxins could lead to several health problems depending on the amount of the toxin consumed. According to the World Health Organization (WHO), aflatoxins are among the most potent mutagenic and carcinogenc substances known, with aflatoxins as the most carcinogenic of all. Ingesting highly contaminated corn or peanuts could lead to severe liver damage, jaundice, haemorrhage, oedema, and eventually death. Even consumption of food stuffs that have low levels of contamination can lead to immunosuppression, nutritional dysfunctions, and liver cancer.
Why aren’t more consumers aware of mycotoxins and aflatoxins?
Bandyopadhyay — People’s awareness of mycotoxins is very poor in both developing and developed countries, for different reasons. If you look at the developed nations, there are functional regulations that limit the entry of toxins into the food system and it doesn’t reach the shelf in the first place. The regulations ensure that the food items that go to consumers are “aflatoxin-safe” already. In developing nations it’s different. I think the reason is that you cannot see the toxin, you cannot taste the toxin. The market lacks the means to differentiate a toxic consignment versus a nontoxic consignment just by looking at it and the consumer can’t differentiate it either. Also, the health impact of the toxins is not immediate. People might not be able to link aflatoxins to illness because those two events will take place very far apart.
What food safety measures are in place to protect consumers from these toxins?
Bandyopadhyay — While nearly impossible to eliminate completely, these toxins are regulated and are only permissible at the most minute level, about four drops in an Olympic-sized swimming pool for most food and at an even lower level for milk. As they are regulated so stringently, they do not pose a problem in most situations, but if unchecked, aflatoxins have been known to kill people. An outbreak in Kenya once caused illness in 315 people, resulting in a death of 1/3 of those patients just in a two week period.
If food safety regulations are so stringent, why do we need to worry about mycotoxins and aflatoxins?
Kablan — Among those most susceptible to aflatoxins exposure, they don’t have the ability to test, identify or measure these toxins as they are not visible to the naked eye. Usually what one can see is the mold if the food is very moldy, but you can’t see aflatoxins themselves. In many cases, the contaminated crop is the main livelihood for a smallholder farmer — and unfortunately, without options for alternative uses, that contaminated crop will oftentimes still be consumed or sold informally for human or animal consumption. Farmers have told us that even if they know the risks and they know the contaminated foods are not healthy, they still eat it out of hunger and need.
Are there ways to prevent mycotoxins and aflatoxins?
Bandyopadhyay — Unfortunately, we don’t have any agrochemical solution for aflatoxins yet, but there have been successes in treating and controlling other types of mycotoxins with crop protection and biotechnology. It is well-known that Bt technology in biotech corn – which is grown over millions of hectares in the U.S. – reduces fumonisin contamination. The reason is that insects, which the Bt varieties resist, cause injury to the corn crop, and the fungus that produces fumonisin gets into the corn through those wounds.
Can the plant sciences play a role in reducing these toxins?
Bandyopadhyay — The part that the plant science industry can play is to breed varieties that are heat-tolerant, drought-tolerant, and adaptable for a particular area. This is important because the key heat stress and drought stress are the predisposing factors for aflatoxin contamination. If you have heat-stress-tolerant and drought-tolerant maize the chances of having aflatoxin in those varieties would be comparatively less.
Kablan — Several multi-disciplinary researchers have been looking at ways to mitigate aflatoxins in the field. Plant scientists are among these researchers who are involved in these efforts. Some research efforts have been focusing on breeding new seed varieties that are resistant to the fungi that produce aflatoxins. Research into identifying low-cost agronomic practices that could help farmers mitigate the problem is needed, as is inexpensive and quick field-based testing to identify contaminated crops.
Are there any successful programs or research you’d like to share with readers?
Bandyopadhyay — There are biocontrol products available to prevent the loss of the entire grain harvest, and when aflatoxin-control methods are adopted, it can improve food security and generate more income because farmers can access a higher premium market. In Nigeria, if farmers have access to biocontrol, they can increase their income by about 16% as well as improve food safety by 13% in maize. We have been working in Africa since 2002 to develop biological solutions for aflatoxins. The product makes use of a naturally-occurring competitive non-toxin producing strains of Aspergillus flavus to eliminate the toxins and has been shown to do so by 80-100% in some cases.
Kablan — At USAID, we have several projects through our Feed the Future Innovation lab working on aflatoxin control and mitigation, which have resulted in the establishment of labs in Africa and Asia. We have also worked with IITA and the Gates Foundation to develop a biocontrol product to control aflatoxins at pre-harvest stages in the field. This product is now being scaled for use in several African countries, including Ghana and Senegal.
Any last thoughts you’d like to leave with readers?
Bandyopadhyay — Food is supposed to be a medicine — there for somebody’s nutrition and for growth and it is important that the food industry continues to work to develop safe supply chains from farm to consumer, to ensure that safe food is accessible to both urban consumers, and more importantly, rural consumers.