Fusarium infection of maize and maize-based products and exposure of a rural population to fumonisin B1 in Limpopo Province, South Africa

Fusarium species (spp.) and fumonisin B-1 (FB1) contaminations were monitored in maize and porridge consumed by a rural population of Limpopo Province, South Africa. Faecal samples were also analysed for FB1 as a means of estimating the degree of dietary exposure to this mycotoxin. In total, 142 samples of maize (n = 54), porridge (47) and faeces (41) were screened for Fusarium spp. using a serial dilution technique followed by DNA sequencing, while FB1 was further screened and quantified by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. At least four species of Fusarium were identified, of which F. verticillioides was the most prevalent in all three sample types analysed. The contamination levels of FB1 were significantly higher in 87% of maize sampled (range = 101-53,863 mu g kg(-1)) as compared with porridge (74% incidence rate; range = 0.2-20 mu g kg(-1)) and faecal samples (100% incidence rate; range = 0.3-464 mu g kg(-1)). Thus, it can be deduced that the level of human exposure to FB1 via the consumption of maize was high as several samples contained levels exceeding 1000 mu g kg(-1), which was strongly supported by the levels found in faecal samples. Further data revealed that a high proportion of FB1 is destroyed or removed by processing maize into porridge. As maize porridge is consumed as a staple, the low levels found provide a means to limit exposure to FB1. Levels of FB1 found in the faeces which were higher indicate that other foods contaminated with the toxin are also consumed.