Health risk assessment for highway toll station workers exposed to PM2.5-bound heavy metals

Highway toll station workers exposed to vehicle emissions during their working time, could induce excessive reactive oxygen species (ROS) generation and lead to significant health effects. This study conducted a comprehensive exposure investigation of environmental pollutants and oxidative stress levels for highway toll station workers during March-May 2014 in Tianjin, China. PM2.5 exposure samples were collected by personal monitors during worker' day-shift working time (9:00 a.m. - 5:00 p.m.), and particulate heavy metals were analyzed by ICP-MS. Urinary 8-OHdG concentrations were analyzed in pre- and post-work urine samples from selected subjects to reflect their oxidative stress (OS) level variation. Results showed that PM2.5 average exposure concentration was 230.73 +/- 142.99 mu g m(-3). Pb, Zn and Cr were the most abundant elements of metals, accounting for over 70% of total particulate heavy metals. Values based on geoaccumulation index (Igeo) and enrichment factor (EF) analysis indicated that heavy metals including Pb, As, Cd, Cr, Ni, Cu, Zn were mainly derived from anthropogenic sources, presenting heavily pollution levels. Health assessment was conducted using integrated toxicity values and Monte Carlo simulation, and results indicated that exposure to PM2.5-bound heavy metals can trigger significant adverse non-carcinogenic and carcinogenic risk. Urinary 8-OHdG concentrations of participants elevated over 2 times after their day-shift working exposure, indicating that pollutants from vehicle emission could cause DNA damage for highway toll station workers. However, we did not find significant association between fine particle-bound heavy metals and urinary 8-OHdG levels. Much work should be conducted in the future study focusing on confounding factors.