Ochratoxin A content of human sera determined by a sensitive ELISA

A sensitive, monoclonal antibody-based ELISA test was developed and used for quantitative determination of ochratoxin A (OA) in human sera. The measuring range of this test (without sample dilution) was 0.2-2.0 ng/mL, and the detection limit was 0.2 ng/mL. The OA concentrations of 355 sera samples varied from < 0.2 to 10 ng/mL OA, but 75% of the samples contained 0.2-1.0 ng/mL. This amount reflects a tolerable daily intake (TDI) value of toxin. However, in some cases (6.8%), more than 1.0 ng/mL OA was measured, which is probably a result of elevated intake of OA, which may even exceed the "virtually safe dose". Our data indicate that, like in many other countries, OA is present in food or feed products available in Hungary, and in order to save the health of consumers, their regular control is desirable.