Mbarara- Uganda: Scientists at Mbarara University of Science and Technology and Makerere University in Uganda, have found disturbing levels of aflatoxins in four staple foods in Western Uganda.
In the study titled “Aflatoxin Susceptible Food Consumption Frequency, Prevalence, and Levels in Household Foodstuffs in Southwestern Uganda,” and published in the Journal of Food Quality, vol. 2023, the scientists conclude that the contamination has been found so alarming that further studies are necessary to explain aflatoxin association with the observed recent increase in hepatocellular cancer and malnutrition in the region.
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, originating in the main liver cells called hepatocytes. It typically develops in individuals with underlying liver diseases such as cirrhosis or chronic hepatitis B or C infections.
The research team which comprised scientists from various departments of the two universities in Uganda, particularly the Pharm-Biotechnology and Traditional Medicine Centre (Pharmbiotrac) at Mbarara University, had Biryomumaisho Justus Murokore from Makerere University in the lead, with expertise in biochemistry and sports science and Agnes Masawi from Mbarara University’s Faculty of Medicine, specializing in biochemistry.
The team also had Alex Wacoo, based at Makerere University’s School of Biomedical Sciences, who contributes his knowledge in medical biochemistry, Raphael Wangalwa, affiliated with Mbarara University’s Faculty of Science, and specializes in biology, Clement Ajayi, associated with Mbarara University’s Faculty of Medicine, along with Peter Vuzi California from the Pharm-Biotechnology and Traditional Medicine Centre at Mbarara University.
Together, this interdisciplinary group collaborated on the research that aimed at addressing issues related to aflatoxin contamination and its impact on food safety in Southwestern Uganda.
How the study was conducted
The study which was conducted in the Southwestern region of Uganda, covered seven districts of which were randomly selected. The selected districts included; Rubanda, Kabale, Rukiga, Sheema, Mitooma, Bushenyi, and Kasese, and subsequent selections were made at different administrative levels, including counties, sub-counties, parishes, and villages.
In each village, up to five households were randomly selected from distinct ecological zones and informed consent was obtained from the head or representative of each selected household. Utilizing an adjusted food frequency questionnaire, the researchers identified the most frequently consumed foods with a high risk of aflatoxin contamination.
A total of 106 samples were collected from households, later reduced to 67 after data cleaning. The collected food samples were sealed tightly, stored in ice-cooled containers, and transported to the laboratories at Mbarara University of Science and Technology and Kyambogo University for storage and aflatoxin quantification at -20°C, respectively.
The findings
Results from the study revealed that maize and groundnut flours are the predominant food staples in daily meals across Southwest Uganda.
Maize flour was found to be the most consumed foodstuff, followed by groundnuts, millet flour, and sorghum – notably in the Rubanda district.
The study found that aflatoxin levels in selected food items, particularly groundnut and maize flours, were alarming.
“Groundnut samples across the region universally exhibited detectable levels of aflatoxin, with a staggering 91% surpassing the regulatory limit of 10 μg/kg. The mean aflatoxin level in groundnut flour reached 96.5, significantly exceeding levels in all other foods, except maize,” the researchers reported in the study that was conducted in 2022 but published in January 2023.
They further reported that maize flour, a dietary staple, presented a mean aflatoxin level of 34.1 ± 14.1 μg/kg, a three-fold increase over the East Africa regulatory limit of 10 μg/kg.
“Approximately 74.2% of maize samples were found to be contaminated, with one sample recording an alarming 336.5 μg/kg, significantly higher than the regulatory limit,” the researchers wrote.
Further analysis of aflatoxin levels in groundnut and maize flours across different districts revealed notable regional disparities.
“Kasese district, in particular, stands out with exceptionally high aflatoxin levels, posing serious health concerns. Sheema district, on the other hand, recorded the lowest mean aflatoxin levels in maize flour at 7.31 ± 7.31 μg/kg,” the researchers observed.
According to the researchers, millet and sorghum, while exhibiting lower overall aflatoxin levels compared to groundnut and maize flours, still raise concerns.
“Millet flour presented a mean aflatoxin level of 11.7 ± 4.2 μg/kg, with 43% of samples exceeding the regulatory limit. Sorghum flour, with a mean aflatoxin level of 12 ± 2.8 μg/kg, showed contamination in 66.7% of samples, with 58.3% exceeding the regulatory limit,” they concluded.
Because of this alarming crisis, the researchers highlighted the urgent need for comprehensive interventions to address aflatoxin contamination in Southwest Uganda’s food supply.
“Authorities, communities, and policymakers must collaborate to implement strategies ensuring food safety, protecting public health, and mitigating the risks associated with aflatoxin exposure,” they warned.
Uganda destroys 1,700 tons of Maize
While these scientists sounded an early warning in January 2023, the authorities in Uganda did not take note until October when the nation was forced to destroy 1,700 tons of maize that were rejected by South Sudan which takes aflatoxin testing seriously in order to safeguard its people.
Last month, Ugandan authorities disposed of 1,700 tons of maize and flour consignment after it was seized by the National Bureau of Standards at the Nimule border point and tested for high levels of aflatoxin in July.
The Ugandan media reported that Mary Gordon Muortat, the CEO of the National Bureau of Standards, confirmed that the goods, valued at $2 million, failed aflatoxin-level tests. Ugandan authorities subjected the goods to a retest carried out by East African Community (EAC) standards experts, and the results confirmed the presence of high aflatoxin levels, specifically B-1.
She also noted that thorough checks are now conducted before any goods enter South Sudan, and the testing and checking of samples are done by South Sudanese staff.
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