Katesiri Satethasilnuchai. Exposure to air pollutants associates with oxidative stress in bus drivers. Master's Degree(Toxicology). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2009.
Exposure to air pollutants associates with oxidative stress in bus drivers
Abstract:
Air pollution is one of the major health problems, especially in an occupationally exposed population such as professional bus drivers. The purpose of this study is to determine oxidative stress status in Bangkok bus drivers (n=100) compared to those exposed to a lower level of air pollution, as control subjects (n=100). The oxidative stress was determined by measuring body antioxidant system including glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and a marker of oxidative damage (malondialdehyde; MDA). Exposure to polycyclic aromatic hydrocarbons (PAHs), a group of major genotoxic carcinogens in urban air pollution, was selected for study for the possibility of association with oxidative stress. The internal PAHs exposure was estimated by urinary 1-hydroxypyrene (1-OHP). All subjects were interviewed by questionnaires. A significant difference was determined at p-value < 0.05. Bangkok bus drivers had significantly lower GSH level, with higher SOD and CAT activities as well as MDA and urinary 1-OHP levels than those of the control subjects. Other confounding factors associated with oxidative stress taken into consideration included cigarette smoking, alcohol consumption and age. Cigarette smoking had a significant association with urinary 1-OHP level in smokers of both the bus driver and the control groups, and thus was a good predictor of this urinary metabolite in both groups of subjects. Only smokers of the bus driver group had an increase in GPx activity with a decrease in GSH level, an effect not observed in the control group. Alcohol consumption caused a decrease only in CAT activity in bus drivers. No other significant changes in antioxidant system, MDA level and urinary 1-OHP were observed in both groups of subjects. The significant positive correlations between SOD-GPx and SOD-CAT were found both in the bus driver and the control groups. For GSH-GPx, a significant positive correlation was found in the control group but was negative in bus drivers. At the older age (> 40 years), a significant increase in GPx activity was observed in bus drivers while an increase in SOD and CAT activities with a decrease in GSH level were observed in the control group. The significant correlations between antioxidants, MDA and age were found only in the control group. So that age was a good predictor of the degree of oxidative damage in a low pollutant exposed group. The results of the study indicated that exposure to air pollutants was probably one of the major factors contributing to oxidative stress in bus drivers. However, oxidative stress status did not seem to be a consequence of PAHs exposure per se, as no significant correlation between 1-OHP and MDA in bus drivers was observed. Cigarette smoking, alcohol consumption and age are also significant factors affecting oxidative stress in both the bus driver and the control groups.