Levels of ochratoxin A in serum from urban and rural Portuguese populations and estimation of exposure degree.

Urban and rural population exposure to ochratoxin A (OTA) in central zone of Portugal was investigated in three places: Coimbra, Verride and Ereira. The analytical method proposed for the determination of ochratoxin A involved extraction with chloroform-orthophosphoric acid, cleanup through an immunoaffinity column (IAC), high performance liquid chromatography (HPLC) with spectrofluorimetric detection (FD) for separation and identification of ochratoxin A, and confirmation with HPLC-FD after OTA methylation in serum. The limit of quantification of the proposed method was 0.1 microg/L for serum and 0.05 microg/L for blood. OTA recoveries in serum ranged from 70.3% to 115.3% for levels at 0.25 microg/L and 0.5 microg/L, respectively, with a within-day RSD between 8.0% and 16.2%. Ochratoxin A serum levels were evaluated in an hundred and four donors from Coimbra city, Verride, and Ereira. The study revealed a frequency of detection of 100%. The ratio of ochratoxin A level in serum to whole blood was 2.0+/-0.7. The overall concentrations range from 0.25 to 2.49 microg/L, 0.14 to 1.91 microg/L, and 0.19 to 0.96 microg/L, for samples of Verride, Ereira, and Coimbra, respectively. The mean concentration and standard deviation were 0.78+/-0.53 microg/L, 0.44+/-0.31 microg/L, and 0.42+/-0.18 microg/L for the same samples. A significant difference was found in Verride population (P-value=0.000). Levels of OTA are clearly higher in males from rural areas than in females. For all samples, a significant difference was found in Verride male population (P-value=0.014).