Diesel generator exhaust emissions: Chemical characterization and cytotoxicity in bladder spheroids

Abstract

Diesel generators, widely used in developing countries, compensating for long power outages and blackouts, are significant sources of air pollution. In this study, diesel exhaust particulate matter (DEPM) samples were collected from two midsize generators operating in Beirut by cascade impaction, and gravimetrically analyzed for size. The smallest fraction captured on quartz filter was then chemically characterized for its constituents, and examined for its cytotoxicity on 2D and 3D human uroepithelial cell cultures. Results showed that 87 % of collected PM are quasi-ultrafine (<0.33 μm in diameter), and marked high emissions of organic and elemental carbon (OC/EC), elements and metals, particularly Ca, Fe, S, Al, and Ti, and polyaromatic hydrocarbons (PAHs), mainly Benzo[g,h,i]perylene and Dibenzo[a,h]anthracene, as well as high emissions of dioxins, furans and polychlorinated biphenyls (PCBs), particularly OCDD, 1,2,3,4,6,7,8 HpCDF, and PCB118. In addition, in vitro testing showed decreased proliferation, viability, and spheroid formation ability only at high concentrations. In conclusion, DEPM from domestic generators consists of a wide panel of potent toxicants, notably genotoxic, carcinogenic, and endocrine disrupting compounds. Additionally, in vitro results provide a solid basis to further examine the potential contribution of DEPM to bladder tumorigenesis in established cell culture models.