Multiple mycotoxin exposure determined by urinary biomarkers in rural subsistence farmers in the former Transkei, South Africa

Subsistence farmers are exposed to a range of mycotoxins. This study applied novel urinary multi-mycotoxin LC-MS/MS methods to determine multiple exposure biomarkers in the high oesophageal cancer region, Transkei, South Africa. Fifty-three female participants donated part of their maize-based evening meal and first void morning urine, which was analysed both with sample clean-up (single and multi-biomarker) and by a 'dilute-and-shoot' multi-biomarker method. Results were corrected for recovery with LOD for not detected. A single biomarker method detected fumonisin B1 (FB1) (87% incidence; mean ± standard deviation 0.342 ± 0.466 ng/mg creatinine) and deoxynivalenol (100%; mean 20.4 ± 49.4 ng/mg creatinine) after hydrolysis with b-glucuronidase. The multi-biomarker 'dilute-and-shoot' method indicated deoxynivalenol-15-glucuronide was predominantly present. A multi-biomarker method with b-glucuronidase and immunoaffinity clean-up determined zearalenone (100%; 0.529 ± 1.60 ng/mg creatinine), FB1 (96%; 1.52 ± 2.17 ng/mg creatinine), a-zearalenol (92%; 0.614 ± 1.91 ng/mg creatinine), deoxynivalenol (87%; 11.3 ± 27.1 ng/mg creatinine), b-zearalenol (75%; 0.702 ± 2.95 ng/mg creatinine) and ochratoxin A (98%; 0.041 ± 0.086 ng/mg creatinine). These demonstrate the value of multi-biomarker methods in measuring exposures in populations exposed to multiple mycotoxins. This is the first finding of urinary deoxynivalenol, zearalenone, their conjugates, ochratoxin A and zearalenols in Transkei.