Coke oven production represents one of the highest exposures of PAHs in the working environment. Genotoxic effects of PAHs on the top-side of coke oven battery were evaluated by the „Single cell gel assay“ (comet assay), detecting the DNA single strand breaks and alkalilabile sites (biomarkers of exposure). Individual susceptibility to PAH exposure was analysed by glutathion S-transferase M1 (GSTM1) polymorphism and N-acetyl transferase 2 (NAT-2) polymorphism detection (biomarkers of susceptibili- ty). The study included 24 subjects from coke-oven, 12 subjects of controls from iron-work and other 16 subjects from town. Exposure to PAHs was determined by personal exposure monitoring 8 h before the collection of blood and urine samples. Coke-oven workers were exposed to carcinogenic PAHs (median, range) in the course of shift 18.7 mg/m 3 (5.1 - 300.2 mg/m 3 ), controls from iron-work 0.41 mg/m 3 (0.12 - 1.22 mg/m 3 ), controls from town 0.58 mg/m 3 (0.09 - 1.64 mg/m 3 ). The following comet parameters were evaluated in peripheral lymphocytes 100 images/sample: percentage of DNA in comet tail (%T), comet tail length (TL) in mm. The highest level of %T and TL was observed in controls from iron-work 14.5 (6.1 - 15.7) and 23.5 (11.6 - 35.8) vs. 6.2 (3.2 - 15.4) and 11.4 (7.4 - 29.5) in coke- oven workers vs. 5.9 (3.8 - 11.0) and 10.9 (8.4 - 20.0) in controls from town, respectively. Any differences were not seen either using coefficient of dispersion. No effects of smoking or GSTM1 or NAT-2 polymorphism were observed for any of comet parameters. According to our results it seems that the comet assay in the peripheral lymphocytes of coke-oven workers was not a particularly sensitive technique to determine the effects of carcinogenic PAHs at the DNA level, if peripheral lymphocytes were used.

        Key words: comet assay, PAHs, coke oven, metabolic polymorphism - GSTM1, NAT-2