Feed the Future Innovation Lab for Food Security Policy Policy Research Brief 83

However, the co-occurrence of aflatoxins and fumonisins in maize poses a significant risk to human and animal health. Aflatoxins are produced by the Aspergillus genus of fungi and are known to be carcinogenic, while fumonisins are produced by the Fusarium genus of fungi and have been associated with esophageal and liver cancers. Studies have demonstrated that the co-occurrence of aflatoxins and fumonisins can have additive or synergistic effects on the development of precancerous lesions or liver cancer in laboratory animals and in vitro studies. In Nigeria, the maize value chain is a long and fragmented supply chain with many actors, creating opportunities for aflatoxin and fumonisin contamination during maize production, handling, and storage. A study conducted in the Greater Ibadan Area of Oyo State in southwest Nigeria explored the occurrence and co-occurrence of aflatoxins and fumonisins in the maize value chain. The study area was selected due to its high probability of exposure to mycotoxin challenges, with maize consumption by humans and poultry production being major drivers of increased maize demand. The study collected maize samples from farmers, maize traders, feed millers, and retailers of maize-based products. The results showed that the total aflatoxin level in farmer's stored maize tends to increase with time of storage, with 87.5% of the samples having aflatoxin levels above the Nigerian maximum total aflatoxin regulatory limit of 4 ppb after 4 months of storage. The total fumonisin levels in maize samples collected from farmers did not follow any specific pattern with length of storage time. In maize samples from local maize traders, the total aflatoxin and total fumonisin levels did not follow any specific pattern with length of storage time. However, the total aflatoxin levels in maize flour samples collected from feed millers were much greater than in the stored maize, with all of the total feed samples having aflatoxin levels higher than 20 ppb, which is the maximum allowable limit in feed set by the USFDA. The study also found that the total aflatoxin levels in samples from farmers, maize traders, feed millers, and maize retailers were well above the national regulatory limits for branded and non-branded maize-based food products. The geometric means of total aflatoxin levels in farmer's maize samples stored for 2-4 months, samples from maize traders stored for over 2 weeks, final feed samples from feed millers, and non-branded maize snacks were higher than 4 ppb, exceeding the set maximum limit for total aflatoxin level in maize by the Standards Organization of Nigeria. The findings of this study highlight the need for adequate addressing of the mycotoxin challenge, which requires consideration of the entire maize value chain. The study's results have significant implications for policy and practice in Nigeria, emphasizing the importance of implementing effective measures to control aflatoxin and fumonisin contamination in the maize value chain.