Ochratoxin A in corn and wheat: geographical association with endemic nephropathy

To determine the presence and concentration of ochratoxin A in wheat and corn from Slavonski Brod surroundings, the area of endemic nephropathy allegedly caused by ochratoxin. Thin-layer chromatography was used to determine ochratoxin A concentrations in 92 wheat and 51 corn samples from the surroundings of Slavonski Brod, Osijek, Hrvatsko Zagorje, Istria, and Celje (Slovenia). Ochratoxin A was present in 74 of 92 (75.8%) wheat samples and 17 of 51 (33.3%) corn samples, in a concentration range of 0.02-160.00 mg/kg in wheat and 0.02-40.00 mg/kg in corn. Wheat samples from the Slavonski Brod surroundings contained the highest level of ochratoxin A (38.8 +/- 27.2 mg/kg), followed by Osijek (8.7 +/- 8.3 mg/kg). Ochratoxin A levels in the wheat from Hrvatsko Zagorje, Istria, and Celje were considerably lower (2.1 +/- 1.5, 1.3 +/- 2.6 and 0.2 +/- 0.5 mg/kg, respectively). Wheat samples from Slavonski Brod significantly differed from all other sample groups (p < 0.001), and wheat samples from Osijek differed from those from Hrvatsko Zagorje, Istria, and Celje (p < 0.001, p = 0.003, p < 0.001, respectively). Ochratoxin A level was the highest in the corn samples from the Slavonski Brod surroundings (20.0 +/- 14.8 mg/kg) and considerably lower in samples from Osijek, Celje, Hrvatsko Zagorje, and Istria (0.8 +/- 1.4, 0.7 +/- 1.9, 0.4 +/- 0.4, and 0.4 +/- 0.8 mg/kg, respectively). A statistically significant difference was also observed between the Slavonski Brod samples and all other corn samples (p < 0.001). Irrespective of the real association between ochratoxin A and endemic nephropathy, our data clearly demonstrate their geographical overlap.