Aflatoxin Contamination of Maize (Zea mays L.) and Groundnut (Arachis hypogaea L.) and its Consequences for the Nigerian Economy: A Review

Abstract

Aflatoxin contamination of maize (Zea mays L.) and groundnut (Arachis hypogaea L.) threatens food safety, livelihoods and agricultural trade in Nigeria. This review synthesises evidence on occurrence, contamination drivers, commodity movement, value-chain and health consequences, African comparisons, and prevention and control options. A targeted narrative review was undertaken using the studies and traceable publications identified for this manuscript, with emphasis on Nigerian evidence and African comparative literature published from 2017 to 2026. Evidence was organised thematically against the nine review objectives; prevalence estimates were not pooled because the included studies differed in commodity, sampling frame, analytical method and reporting threshold. Recent Nigerian studies report substantial contamination: a systematic review of 25 studies and 1,627 maize samples found marked seasonal and agroecological variation, while a 2026 survey detected total aflatoxins in 92.2% of 90 composite maize samples (mean 39.58 μg/kg). A 2025 study of maize from north-western Nigeria detected aflatoxins in 80.9% of samples, and recent Nigerian groundnut evidence also indicates substantial exposure concerns. Contamination is associated with crop stress, insect damage, delayed harvesting, inadequate drying, poor storage and weak traceability. Contaminated commodities can move through informal domestic markets and cross-border supply chains, creating costs for farmers, traders, processors and livestock producers, alongside food-security and public-health risks. Evidence from Nigeria and other African countries supports integrated control, including good agricultural practices, rapid drying, improved storage, testing, traceability and locally adapted biological control. The review concludes that coordinated value-chain prevention, affordable testing and market incentives for verified safer produce are important opportunities to reduce exposure and protect trade competitiveness.