Exposure of rural and urban populations in KwaZulu Natal, South Africa, to fumonisin B₁ in maize

We surveyed households in rural and urban areas of KwaZulu Natal, South Africa, to assess the exposure of the inhabitants to fumonisn B₁ (FB₁), a mycotoxin produced by Fusarium verticilioides. In southern African regions maize, used as a staple food by the population, is prone to F. verticillioides infection. Furthermore, high levels of FB₁ in maize have been associated with esophageal cancer in South Africa. We assessed exposure of the population to FB₁ at three levels, namely, by analyzing stored maize, plate-ready food, and feces. The positions of participating households in the rural area were recorded using geographic information systems (GIS) for ease and accuracy of follow-up. Of the 50 rural maize samples examined, 32% had levels of FB₁ ranging from 0.1-22.2 mg/kg, whereas 29% of the 28 cooked maize (phutu) samples contained FB₁ ranging from 0.1-0.4 mg/kg. The incidence and levels of FB₁ in feces were 33% and 0.5-39.0 mg/kg, respectively. Of the 49 urban maize samples analyzed 6.1% had a range of 0.2-0.5 mg/kg FB₁, whereas 3 of 44 fecal samples (6%) ranged between 0.6 and 16.2 mg/kg. No FB₁ was detected in urban phutu samples. Because these levels are lower than those published from regions in South Africa with high incidence of esophageal cancer, it may be concluded that the risk of esophageal cancer from FB₁ exposure is lower in the KwaZulu Natal region.