Prevalence and Risk Assessment of Multiple Mycotoxins in Durum Wheat from Fields Under Different Agricultural...

Mycotoxin contamination in wheat, a staple food critical to human nutrition, poses significant public health concerns. This study investigated the natural occurrence of 17 mycotoxins in Tunisian durum wheat, assessed the influence of soil tillage practices on mycotoxin contamination, and performed an associated exposure risk assessment. A total of 167 wheat samples were randomly collected over two years (2021 and 2022) from fields managed under conventional tillage (CT) and no-tillage (NT) systems during both pre- and post-harvest periods. Mycotoxins were extracted using the QuEChERS method and quantified via UHPLC-MS/MS. The results demonstrated contamination by ZEN, DON, OTA, ENA1, ENB, and ENB1. Among regulated mycotoxins, OTA was the most prevalent, detected in 68 out of 167 samples with a mean concentration of 1.85 µg/kg. ZEN was the most abundant, detected in 65 samples with a mean concentration of 26.85 µg/kg, while DON was less frequently detected in 62 samples with a mean concentration of 0.68 µg/kg. Regarding emerging mycotoxins, ENB was the most prevalent and abundant, found in 51 samples with a mean concentration of 10.13 µg/kg; ENB1 and ENA1 were detected in 20 and 10 samples, with mean concentrations of 3.38 µg/kg and 1.69 µg/kg, respectively. Furthermore, mycotoxin concentrations varied according to agricultural practices. DON, ZEN, ENA1, ENB, and ENB1 showed higher frequencies and concentrations (ranging from 0.08 to 210.11 µg/kg) in samples collected during the 2021 pre-harvest period from NT fields. In contrast, OTA exhibited greater prevalence and higher concentrations (ranging from 2.33 to 9.78 µ/kg) in samples collected during the 2022 post-harvest period from CT fields. The Estimated Daily Intake (EDI) of mycotoxins by Tunisian adults was calculated based on contamination levels in raw durum wheat from fields under NT and CT practices, resulting in the following values (ng/kg bw/day), with the first value corresponding to NT samples and the second to CT samples: OTA (17.3; 20.8), ZEN (466.3; 194.0), DON (8.0; 7.56), ENA1 (4.30; 18.85), ENB (105.17; 121.08), and ENB1 (49.91; 40.91). Both the Margin of Exposure (MOE) values for OTA and the Hazard Quotients (HQ) for ZEN and DON exceeded established safety thresholds, indicating potential health risks for Tunisian adults. These findings highlight the urgent need to implement stricter mycotoxin regulations in Tunisia and enhance surveillance systems. Further research is warranted to elucidate the mechanisms by which soil tillage practices influence mycotoxin contamination and to develop targeted mitigation strategies to ensure food safety.