Farmers sun-dry maize to avoid soil contamination and aflatoxin infection. Photo by: International Institute of Tropical Agriculture / CC BY-NC-SA

NAIROBI — A small organization in Nairobi’s Mathare slum that spreads positive social messages through music is taking on an unlikely foe: maize, the country’s primary staple food. It is doing this in an effort to cut down the consumption of aflatoxins — a type of toxin produced by fungus that clings onto crops, especially maize, when the crops are not dried and stored properly, and which causes liver cancer and can be deadly at high levels of exposure.

“From a human rights, food justice, and public health point of view, it’s a crisis.”

— Dr. Michael Hauser, principal scientist, ICRISAT

Billian Music Foundation is producing a song, which it hopes to roll out nationally, which aims to influence Kenyans to decrease the quantity of maize they eat, driving them to alternatives, such as millet.  

Its efforts are in partnership with the International Crops Research Institute for the Semi-Arid Tropics, which has worked to map out food consumption patterns in Mathare — talking with food vendors and community members to identify what people are eating, what drives people’s food preferences, and what sort of access there is to alternatives. ICRISAT is also doing similar work in urban areas in Zimbabwe and Malawi.

While seemingly harmless, consumption of maize can be dangerous in this part of the world. Kenya is one of the world’s hotspots for aflatoxins. Poisonous levels of aflatoxins have reportedly killed at least 157 people in Kenya and the overconsumption of maize is also contributing to the country’s growing burden of cancer

A lesser known side effect of chronic exposure to aflatoxins is the role it could play in reduced nutrient absorption in children, leading to stunting.

Because of these concerns, Billian Music Foundation is also targeting children in particular. It has a day care for children from the community living with disabilities and has switched from providing meals of maize porridge to millet porridge.

But persuading the wider community, and country, to eat less maize won’t be easy. Kenyans love maize, which is often turned into ugali — a starchy side dish served with many traditional Kenyan meals.

“Convincing Kenyans to not eat maize is an uphill task,” said Heldrine Omega, a Nairobi resident, who despite knowing of the dangers of aflatoxins still eats it at least once per day.

Public health ‘crisis’

The problem hit a peak in Kenya in 2004, when an outbreak of aflatoxin poisoning led to 125 deaths from contaminated maize — one of the most severe cases of aflatoxin poisoning in history.  

Over a decade later, the problem still exists, and huge swaths of the population aren’t even aware of the health risks associated with eating maize. In November, the Kenya Bureau of Standards banned a number of brands of maize and peanut butter that were not safe for human consumption.

The problem stretches beyond Kenya into large areas across sub-Saharan Africa. The fungus is common in warm and humid climates.

One strain of aflatoxin has been classified as a Group 1 human carcinogen. Aflatoxin exposure is responsible for an estimated 30% of liver cancers diagnosed across the African continent.

“From a human rights, food justice, and public health point of view, it’s a crisis,” said Dr. Michael Hauser, principal scientist at ICRISAT.

Beyond maize, it is also commonly found in peanuts, among other crops and animal products, such as milk, when the livestock eats aflatoxin-contaminated feed.

Key reasons behind the problem include improper drying and storage of crops, a lack of information among farmers and consumers about the problem, and lax enforcement of regulations, according to aflatoxin experts.

“Aflatoxin exposure, to some extent, is an expression of poverty.”

—  Dr. Michael Hauser, principal scientist, ICRISAT

Aflatoxin contamination is also difficult to test for because concentrations of the toxins could exist within pockets of a product, rather than consistently throughout, Hauser said.

While aflatoxin exposure is present across income levels throughout many sub-Saharan African nations, people living in low-income situations are particularly vulnerable because food options such as maize are cheaper than alternatives like millet, he said.

“Aflatoxin exposure, to some extent, is an expression of poverty,” Hauser said.

Millet is also less abundant in local markets and is harder to cook.

The problem of aflatoxin exposure is expected to worsen with climate change, as the region becomes more prone to extreme weather — including drought and flooding.

Drought leaves crops weak and more vulnerable to the fungal infection, and flooding leads to crops not drying properly, Erastus Kangethe, aflatoxins expert formerly at the University of Nairobi, told Devex.

Absorption of nutrients

There is also a growing body of evidence that chronic aflatoxin exposure interferes with nutrient absorption and immune function, leading to malnutrition and stunting in children.

Children in sub-Saharan Africa risk being exposed to aflatoxins in the womb, during breastfeeding, in food provided during weaning, and throughout their lives.

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While the link to malnutrition is not clear, there are some theories. This includes the toxins altering the intestines in a way that disrupts nutrient absorption, leads to zinc deficiencies, and makes people more vulnerable to intestinal pathogens. It can also lead to immune system dysfunction resulting in a person losing energy because of illness.

“It interferes with the integrity of the gut and its ability to absorb nutrients,” said Immaculate Edel Moruri, nutritionist at ICRISAT. “A young child really needs these nutrients because they are in a phase in their life where they need optimal food for development.”

The challenge in drawing a direct link between stunting and aflatoxins lies in socioeconomics. Aflatoxin exposure is linked to poverty — so other factors can be included to lead to childhood stunting, including poor access to nutritious foods and more frequent infections, such as chronic diarrhea.

“We are not able to control the variables. There are too many and they are too complex,” Kangethe said.

Up until last year, most of the research published examining this link has been observational. This included studies that showed that chronic exposure to aflatoxins in children was linked to poor growth and immune status, as well as kwashiorkor, a form of severe protein malnutrition.

Results from the first randomized controlled trial, conducted in Kenya, published last February, suggested that exposure “may affect linear growth at younger ages,” but left lingering questions, such as how exposure could impact children at different ages, how much of a reduction in exposure to aflatoxins is needed to prevent stunting, and how aflatoxin exposure relates to other factors that  influence stunting.

A recent study from East Timor found that relatively low levels of aflatoxins in children did not have a correlation with stunting. Comparatively, higher levels in children in Tanzania also did not show a correlation, but much higher levels of the toxins in children in Benin and Togo found a correlation with reduced growth.

Other researchers suggest that a link to stunting has been overexamined, and that researchers should give more focus to the carcinogenic nature of the toxin, as well as the contributions the toxin could have on “enteric dysfunction, systemic inflammation, immunomodulation, and changes in the hepatic metabolism of micronutrients,” which also can impact children’s development and future productivity.  

Because of the myriad public health risks, organizations such as the World Food Programme have a rigorous system aimed at avoiding aflatoxin contamination in the food they provide communities — including Plumpy’Sup, a peanut-based product used widely to both help children treat and avoid malnutrition. But due to the widespread nature of the problem, communities can be exposed in many other ways.

“You go to the local markets and you find that the level of aflatoxins … is just incredibly high and there is no control over it,” said Jean-Pierre Leroy, chief food safety and quality assurance at WFP.

The problem has also hampered the ability of some African nations to export their crops to markets such as the European Union.

Improving farming practices

Some of the mitigation efforts to tackle aflatoxins include reducing crop stress through tactics such as the use of irrigation, fertilizer, insecticides, and fungicides, according to aflatoxin experts. Post-harvest solutions include the proper drying of crops, use of bags with appropriate air circulation, and crop storage in areas that are not humid and where insecticides are used.

Another mitigation measure includes Aflasafe, a product that uses the same kind of fungus that produces aflatoxin, but a strain that doesn’t produce the toxin. This “safe” fungus occupies the crops, crowding out the strain that causes the toxin.

The Kenyan government, in partnership with the United States government, the International Institute of Tropical Agriculture, and the Bill & Melinda Gates Foundation commissioned the first manufacturing facility for Aflasafe in East Africa in October last year.

At continent-wide level, the Partnership for Aflatoxin Control in Africa, hosted by the African Union Commission, is also working to combat the issue — in areas such as research, development of control technologies, scaling up existing technologies, and building capacity along the agricultural value-chains across the continent.

This focus area, powered by DSM, is exploring innovative solutions to improve nutrition, tackle malnutrition, and influence policies and funding. Visit the Focus on: Improving Nutrition page for more.

About the author

  • Sara Jerving

    Sara Jerving is a global health reporter based in Nairobi. Her work has appeared in The Wall Street Journal, The New York Times, the Los Angeles Times, Vice News, and Bloomberg News, among others. Sara holds a master's degree from Columbia University Graduate School of Journalism where she was a Lorana Sullivan fellow. She was a finalist for the Livingston Award for Young Journalists in 2018, part of a Vice News Tonight on HBO team that received an Emmy nomination in 2018 and received the Philip Greer Memorial Award from Columbia University Graduate School of Journalism in 2014. She has reported from over a dozen countries.

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