Aflatoxin contamination of maize flour in Kenya: Results from multi-city, multi-round surveillance

TL;DR

This study finds high aflatoxin contamination in Kenyan maize flour, especially in informal markets, highlighting the need for food safety interventions.

Contribution

The study provides new evidence on aflatoxin levels in both formal and informal maize flour markets in Kenya.

Findings

97% of maize flour samples had detectable aflatoxin, with 16% exceeding Kenya's 10 ppb limit.

Informal market samples had significantly higher aflatoxin levels than formal sector samples.

Aflatoxin levels showed seasonal variation, peaking in June and declining in December.

Abstract

Foodborne illness is a major source of the global burden of disease, but public monitoring of hazards in food systems is overwhelmingly focused on the formal sector in high income countries. We contribute to the development of an evidence base on food safety risk in low-income and informal settings by monitoring aflatoxin prevalence in maize flour in Kenya. Aflatoxin is a contaminant which causes liver cancer and has been linked to childhood stunting. We carry out systematic monitoring of formally and informally processed maize flour from a range of retail vendors across ten urban sites in Kenya and analyze aflatoxin levels in commercial samples. Samples were obtained every two months from February-December 2021 and 1255 samples in total were analyzed. Almost all samples (97%) showed detectable levels of aflatoxin, with 16% of tested samples exceeding the national regulatory limit of 10 ppb. Mean contamination levels are significantly higher (p < 0.001) in informal market samples (9.9 ppb) than in packaged flour in the formal sector (4.9 ppb). We find important seasonal variation in aflatoxin levels, which are highest in our June sample and lowest in December, which we attribute to variation in sourcing of maize grain. Our results demonstrate the need for policy interventions to reduce aflatoxin exposure in Kenya and demonstrate the utility of coordinated monitoring efforts to track levels of food safety risk in low-income settings.

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