Particulate matter bound polycyclic aromatic hydrocarbons: Toxicity and health risk assessment of exposed inhabitants

In the present study, the toxicological profile of 13 polycyclic aromatic hydrocarbons (PAHs) associated with airborne particulate matter (PM) was assessed. The average concentration of both PM10 and PM2.5 exceeded the Indian National Ambient Air Quality Standards. Amongst 13 analyzed PAHs, Naphthalene (Nap) was found to be the most dominant in both size fraction of PM whereas Indeno (1, 2, 3-cd) pyrene (IP) exhibited the least concentration. The relative % distribution of Low molecular weight (LMW) three ring PAHs were found to be predominant in both sized PM. The combined results derived from diagnostic ratios and factor analysis suggested that the vehicular emission (Diesel + gasoline) and coal combustion in the vicinity of study province are probable sources of PM bound PAHs. Maximum contribution towards the carcinogenicity has been found for Benzo (a) pyrene [B(a)p] for both size PM. The cytotoxic profile of PAHs determined by MTT assay demonstrated significant decrease in cell viability and PAHs associated with PM10 samples exhibited higher cytotoxic response. The redox activity measured by DTT assay exhibited the oxidative nature of PAHs associated with both sized PM. The interaction study between the PAHs and BSA resulted in substantial decrease in fluorescence intensity of BSA, indicating that PM bound PAHs could quench intrinsic fluorescence of the protein through successive molecular interaction and further conformational changes of protein was confirmed by circular dichroism spectra. Results obtained in the present study provide a valuable approach to evaluate the toxicological profile of PAHs encountered in the atmosphere of Pune.