2. Department of General Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
3. National Center of Excellence for Environmental and Hazardous Waste Management (NCE-EHWM), Chulalongkorn University, Bangkok 10330, Thailand.
Background: Benzene, formaldehyde and acetaldehyde are carcinogenic substances to which gasoline station workers are most likely exposed via inhalation. To evaluate these compounds in the ambient air of gasoline stations, the inhalation exposure test on workers was performed and assessed. By the appropriate intervention of wearing mask and hand washing during work shift, we determined whether or not there is cancer risk to the exposure of benzene, formaldehyde and acetaldehyde using urinary biomarkers.
Methods: A cross sectional study was conducted in 38 workers of 6 gasoline stations in Pathumwan District, Bangkok, Thailand. Inhalation and ambient air concentrations of benzene, formaldehyde and acetaldehyde were evaluated by GC/FID and HPLC/UV detectors. Urinary trans, trans-muconic acid (t,t-MA), formaldehyde and acetaldehyde concentrations detected in gasoline workers before and after appropriate intervention were analyzed by GC/FID.
Results: The average inhalation exposure concentrations of benzene, formaldehyde and acetaldehyde were 195.56, 12.60 and 5.74 μg/m3, respectively. The level of benzene exposure was significantly higher than the ambient air level (independent t-test, p < 0.01). The average lifetime cancer risk of the workers exposed to benzene, formaldehyde and acetaldehyde was determined at the values of 2.15E-04, 1.27E-05 and 2.69E-06, respectively. Benzene and formaldehyde values were higher than an acceptable criteria defined as 1E-06. The amount of urinary t,t-MA, formaldehyde and acetaldehyde in the workers daily after 7-days appropriate intervention (wearing masks as personal protective equipment (PPE) and hand washing) was decreased. Formaldehyde and acetaldehyde, which were detected in urine, showed significantly lower than before intervention (pair t-test, p < 0.001).
Conclusions: Results from our study confirmed that the gasoline workers have high chances of cancer risk from daily exposure to benzene and formaldehyde. The urinary's t,t-MA, formaldehyde and acetaldehyde could be considerably used as biomarkers in gasoline station workers. An appropriate intervention, using PPE and hand washing, could reduce the cancer risk.