Multiple mycotoxins associated with maize (Zea mays L.) grains harvested from subsistence farmers' fields in southwestern Ethiopia

Fifty-four maize grain samples freshly harvested from subsistence farmers' fields in southwestern Ethiopia were analyzed for multiple mycotoxins using liquid chromatography-tandem mass spectrometric (LC-MS/MS) method following extraction by acetonitrile/water/acetic acid on a rotary shaker. The grain samples were contaminated with a total of 164 metabolites, of which Fusarium and Penicillium metabolites were the most prevalent accounting for 27 and 30%, respectively. All the major mycotoxins and derivatives except one (citrinin) were of Fusarium origin. Zearalenone was the most frequent major mycotoxin occurring in 74% of the samples at concentrations of 0.32-1310 µg/kg. It was followed by nivalenol (63%), zearalenone-sulfate (44%), and fumonisin B1 (41%). Nivalenol, nivalenol glucoside, and fusarenon-X were detected at unusually high levels of 8-1700 µg/kg, 21-184 µg/kg, and 33-149 µg/kg, respectively. Deoxynivalenol and DON-3 glucoside contaminated 32% of the samples, each at levels of 15.9-5140 µg/kg and 10-583 µg/kg, respectively. Moniliformin and W493B occurred in 96 and 22% samples at levels of 3.27-4410 µg/kg and 3-652 µg/kg, respectively. Fumonisins were also detected in the samples at levels of 9-6770 µg/kg (B1), 16-1830 µg/kg (B2), 9.5-808 µg/kg (B3), and 1.3-128 µg/kg (A1). This study confirmed the presence of an array of mycotoxins contaminating maize grains right from the field. The effect of the co-occurring mycotoxins on consumers' health should be investigated along with that of the newly emerging ones. Results of the current study call for application of pre-harvest mycotoxin mitigation strategies to safeguard maize-based food and feed.