This archive report was first published on 4 December 2019.
Maize flour is a staple food in Kenya, but it's often contaminated with aflatoxins, a type of toxic chemical produced by a fungus. According to a recent exposé, many popular maize flour brands contain high levels of aflatoxins, which can be fatal in large doses and have other potential health impacts.
The fungus that produces aflatoxins, Aspergillus flavus, occurs naturally in soils and can grow on crops under hot, dry conditions. Maize and groundnut are two crops that are especially susceptible to contamination with aflatoxins. While some of the health impacts of consuming moderate amounts of aflatoxin over long periods of time are less well understood, it's known that aflatoxin is a carcinogen.
The amount of harvest that's affected by aflatoxins varies each year, depending on the weather. Either too little rain during cultivation or too much around harvest can lead to higher aflatoxin levels. Poor plant nutrition is also a risk factor, as it weakens crops and makes them susceptible to being colonised by fungus.
Proper storage and drying of crops are also crucial in preventing aflatoxin contamination. In Kenya, maize stored by smallholder farmers has been found to be far more contaminated than purchased maize, and is the most likely culprit for the outbreaks of aflatoxin poisoning that occur from time to time.
While some food processing companies test inputs before buying to avoid aflatoxin contamination in their products, accurate testing is difficult because there is a lot of variation in aflatoxin across bags of maize, and even grains within a bag. Under Kenyan law, maize that contains more than 10 parts per billion total aflatoxin, and groundnut above 15 parts per billion aflatoxin, cannot legally be sold.
However, testing procedures are not regulated, and when a consignment of maize or groundnut is rejected by one company, it is simply sold to another with less stringent requirements, or on the informal market. This means the lowest-cost food is often the most contaminated, and people with the least to spend are at greatest risk of eating unsafe food.
Research has shown that more expensive brands are more likely to be compliant with the aflatoxin standard, and buying higher-priced maize flour is one way to protect yourself. Additionally, if you grow your own maize or groundnut, dry your crops thoroughly while preventing contact with the soil, and store them in a clean, dry place.
Processed foods containing groundnut are usually more contaminated than whole nuts, and grinding your own peanut butter from high-quality nuts is one way to avoid aflatoxin in this food. Finally, eating a balanced diet and avoiding over-reliance on maize and groundnut can also help reduce the risk of aflatoxin poisoning.
What needs to happen next? More resources are needed to deal with aflatoxin contamination at its root, which is on the farm. The Kenyan government recently announced plans to spend Ksh200 million ($2 million) on Aflasafe, an aflatoxin-control product that farmers apply to crops while they are still in the field.
However, it's extremely important that farmers are trained on how to correctly apply it for the treatment to be effective. Other practices, including drying crops on plastic sheets, removing visibly mouldy or damaged crops prior to storage, and storing well-dried crops in hermetic bags, are also very effective at reducing aflatoxin.
There also needs to be a change in Kenya's aflatoxin regulation to legalise the use of contaminated grain for specific non-food uses. The East African Standard for maize, which Kenya follows, requires all maize to meet the same aflatoxin limit, regardless of its use.
Allowing food that exceeds the aflatoxin limit for human consumption to be fed to meat animals is a way to get this poison out of the food supply. Many countries, including the US and EU members, allow higher levels — up to 30 times the Kenyan limit — in feed consumed by meat animals.
By investing in aflatoxin-control products and providing training to farmers, and by changing the regulation to allow for the use of contaminated grain for non-food uses, Kenya can take significant steps towards reducing aflatoxin contamination in its food supply.
