Health risk assessment of atmospheric polycyclic aromatic hydrocarbons over the Central Himalayas

Carcinogenic risk assessments of polycyclic aromatic hydrocarbons (PAHs) in four sites from the Central Himalayas (Bode, Lumbini, Pokhara, and Dhunche) were performed. Lifetime Average Daily Dose (LADD), Lifetime lung cancer risk (LLCR) and Incremental lifetime cancer risk (ILCR) were calculated in order to evaluate the cancer risk. PAHs levels were converted to BaP equivalent concentrations (B[a]Peq), and models of health risk assessment were applied. B[a]Peq concentrations exceeded the standard limited value (1 ng/m(3)) in all the four sites. The human health risk assessment (HHRA) demonstrated high carcinogenic risk on residents of Bode and Lumbini. Further, LLCR in all sites were over the acceptable range (1.15E-03, 7.90E-04, 1.40E-04 and 9.96E-05, respectively); however, ILCR ranking exhibited acceptable range in Lumbini, Pokhara, and Dhunche (7.10E-06, 1.26E-06, and 8.95E-07). The risk variation among the sites is due to the difference in pollution status. The study shows health risk due to atmospheric PAHs via inhalation prevails all the seasons throughout, differing only seasonally; nevertheless, the concentration and carcinogenic risk decreased remarkably from south-north transect of the central Himalaya. Keeping some uncertainties aside, this study provides noble insights and helps to formulate new advance assessment on the carcinogenic risk of atmospheric PAHs over the Central Himalayas.