Determination of Persistent Organic Pollutants

Serum concentrations of 6 PCB congeners (PCB118, PCB153, PCB138, PCB156, PCB170 and PCB180), DDE and HCB were determined by means of a Agilent 6890 gas chromatographer connected to a Waters Autospec Ultima high resolution mass spectrometer as described in an earlier study on the exposure data^{12 (link), 13 (link)}. Per subject we calculated a Z-Score_(POPs) as a representative of the internal exposure to the mixture of POPs. The Z-Score_(POPs) was defined as the sum of the Z-Scores for each compound: Z-Score_(compound) = (X − μ)/σ (where X represents the value of the subject, μ the mean and σ the standard deviation of the population)^{42 (link)}. Therefore, Z-Score_(POPs) = Z-Score_(PCB118) + Z-Score_(PCB153) + Z-Score_(PCB138) + Z-Score_(PCB156) + Z-Score_(PCB170) + Z-Score_(PCB180) + Z-Score_(HCB) + Z-Score_(DDE).