Aflatoxins can cause liver cancer

Thursday April 22 2021
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Innocent Atuhe

By Guest Writer

Early March this year, Kenya, a country where maize is a major food crop, stopped the importation of maize from Uganda because of quality concerns.

Their main complaint about Ugandan maize, according to media reports, was the presence of aflatoxins in the maize. Uganda loses more than $38 million (Shs140b) as a result of failure to export grains due to aflatoxins. In 2013, more than 600,000 tonnes of maize worth Shs10b destined for neighbouring Kenya was also rejected because they contained aflatoxins. Aflatoxins pose a significant economic burden, causing an estimated 25 per cent or more of the world’s food crops to be destroyed annually.

Aflatoxins in Uganda are produced by Aspergillus flavus and A. parasiticus and these have been found in maize, sorghum, sesame, beans, sunflower, millet, peanuts, and cassava. The causes and proliferation of aflatoxigenic contamination of Ugandan foods have been largely due to poor pre, peri, and post-harvest activities, poor government legislation, lack of awareness, and low levels of education among farmers, entrepreneurs, and consumers on this plague. Little diet diversity has exacerbated the risk of exposure to aflatoxins in Uganda because most of the staple foods are aflatoxin-prone

According to the National Grain Trade policy, as of 2015, only 5 per cent of the produced grain was being stored as per recommended standards of grain storage, 37 per cent was lost after harvesting, and only 12 per cent of the farmers had access to standard agro-processing facilities for cleaning, drying, and grading grain. Researchers from Makerere University reported that more than 45 per cent of grain in Uganda is infested with aflatoxins and this is a danger to the health of the people. This situation is unacceptable and remediable.

According to World Health Organisation, Aflatoxins are poisonous substances produced by certain kinds of fungi (moulds) that are found naturally all over the world; they can contaminate food crops and pose a serious health threat to humans and livestock. Aflatoxins are of the greatest concern to food safety due to their wide distribution in foods and feeds and their high toxicities. Since their discovery, aflatoxins have been associated with liver cancer, with peanut, maize and their derivatives being the main vehicles. These naturally occurring fungal toxins are known to contaminate important food crops, such as maize, and unfortunately, are not simple or cheap to detect and address.

Long-term or chronic exposure to aflatoxins has several health consequences including being potent carcinogens and may affect all organ systems, especially the liver and kidneys; they cause liver cancer, and have been linked to other types of cancer. 

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According to International Food Policy Research Institute, up to 172,000 liver cancer cases per year are attributable to aflatoxin exposure. In addition, aflatoxins have the potential to cause birth defects in children; stunting, immunosuppression and therefore may decrease resistance to infectious agents and can cause acute poisoning that can be life threatening.

Research has found that technology is key in addressing the aflatoxin problem but so are well-designed policies, programmes and regulations, and education and awareness among farmers and consumers. 

Control measures are required both pre- and postharvest. The most long-term, stable solution to controlling pre-harvest aflatoxin contamination is through enhancing the ability of the crop to resist fungal infection and/or prevent production of aflatoxins by the invading fungus. This can be achieved through plant breeding or through genetic engineering of crops of interest. 

Control is needed at all stages from the field to the table. Such an approach includes targeted plant breeding practices, enhancement of host plant resistance, and biological control methods, coupled with post-harvest technologies such as proper drying and storage of potentially affected crop products, as well as development of appropriate alternative uses to retain at least some economic return on value of damaged crop.

Mr Innocent Atuhe works with King Ceasor University Centre for Research, Innovation and Publication.

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