Ibadan, Nigeria
3 March 2023
Maize is one of Tanzania’s most important food crops, and the country is the largest producer in East Africa. Groundnut, another major staple, is one of the chief annual crops cultivated in Tanzania. Both crops, produced mainly by smallholder farmers, are the most affected by aflatoxins—a highly toxic, cancer-causing food contaminant.
Smallholder farmers harvesting groundnuts.
Tanzania faces lots of challenges in achieving full production potential for these crops. While efforts to scale agricultural productivity to achieve the sustainable development goals of food safety and security and zero hunger are being promoted in sub-Saharan Africa, aflatoxin contamination is negatively affecting food production, consequently threatening food safety and security.
According to a study carried out in Tanzania, aflatoxin producers are pervasive in warm agricultural areas where they occupy soil and colonize diverse organic matter. Researchers introduced biocontrol products containing atoxigenic isolates of Aspergillus flavus—the non-toxin-producing strains—to reduce aflatoxin content in maize and groundnut.
Scientists from multiple organizations collaborated on the study, including CGIAR–IITA; Plant Health Services of Tanzania’s Ministry of Agriculture; the Department of Research of Tanzania’s Ministry of Livestock and Fisheries; National Biological Control Center; and the U.S. Department of Agriculture Agricultural Research Service (USDA-ARS).
The study tested the efficacy of aflatoxin biocontrol products, Aflasafe TZ01 and TZ02, on maize and groundnut in four regions of Tanzania over two years. It revealed that the two products significantly reduced aflatoxin levels in maize and groundnut by over 85%. This occurred in all four regions indicating that both products are effective tools for aflatoxin mitigation in groundnut and maize.
Aflatoxins are naturally occurring toxic compounds produced by the fungi belonging to Aspergillus section flavi and are dangerous in minute concentrations. Due to the acute and chronic health effects on humans and domesticated animals, minimizing aflatoxin contamination, especially in maize and groundnut, will prevent millions from adverse health conditions in Tanzania and across Africa.
Aflatoxin has been identified as one of the causes of health conditions like liver cirrhosis and cancer, while exposure to it can lead to potential negative nutritional and immunological effects. It has also been linked to substantial economic losses for farmers.
The study revealed that smallholder farmers eat most of what they grow; hence, aflatoxin has a high impact on the health of the local population.
According to IITA Senior Plant Pathologist and Country Representative for Uganda, George Mahuku, a case of acute aflatoxin poisoning was reported in two districts (Chemba and Kondoa) of Tanzania in 2016. More than 69 people were affected after consuming products from contaminated maize, and 20 lost their lives.
Subsequently, trials to validate Aflasafe products for controlling aflatoxin were conducted in the two districts. Farmers were happy that the solutions to aflatoxin contamination were being validated in their community.
“We urgently need a solution to this poison that is making our children sick,” said Mwajabu Mohamed, who, together with six members of his family, fell ill after consuming maize that was contaminated with aflatoxin. Luckily for him, all his family members recovered, as they quickly sort medical attention. Mohamed eagerly hosted Aflasafe trials on his farm. The products are now fully registered in Tanzania and available to farmers.
Adopting these biocontrol products can help farmers in Tanzania produce aflatoxin-safe food, thereby improving health and increasing chances for greater income for smallholder farmers. It would also significantly increase farmers’ chances of meeting stringent aflatoxin thresholds imposed by local and international premium markets.
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