Evaluation of DNA damage induction on human pulmonary cells exposed to PAHs from organic extract of PM10 collected in a coke-oven plant.

Occupational exposure of coke oven workers, classified by IARC as human carcinogen, is characterized by the presence of PAHs emitted during pyrolysis of coal. We aimed to clarify the mechanism of action of complex mixtures of PAHs and to identify biomarkers of early biological effect, evaluating on lung epithelial cells (A549) genotoxic and oxidative damage of airborne particulate matter collected in a coke plant. Particulate matter was collected in the oven area on glass filter, extract and analysed by GC/MS. Direct/oxidative DNA damage induced by exposure to extract were evaluated by Fpg comet assay. The cells were exposed for 30 min, 2h and 4h to extract of half filter diluted at 0.004%, 0.008% and 0.02%. We evaluated comet percentage and analysed tail moment values of cells treated with Fpg enzyme (TMenz) and untreated (TM) that indicate respectively oxidative and direct DNA damage. Air sample contained 0.328 microg/m3 of pyrene, 0.33 microg/m3 of benzo(a)anthracene, 1.073 microg/m3 of benzo(b)fluoranthene, 0.22 microg/m3 of benzo(k)fluoranthene, 0.35 microg/m3 of benzo(a)pyrene, 0.079 microg/m3 of dibenzo(a,h)anthracene and 0.40 microg/m3 of benzo(g,h,i)perylene. The dose-dependent increase of TM and TMenz in exposed cells was not significant, indicating only a slight direct and oxidative DNA damage in exposed cells. A small dose-time dependent increase of comet percentage was found. The study shows the high sensitivity of comet assay to measure early DNA damage also at low doses suggesting its use on lung epithelial cells to evaluate the effects of complex mixtures of genotoxic substances on target organ.