1400 Benzene exposure and human health risk assessment via biological monitoring among workers at gasoline stations

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A low benzene concentrations in working environment at gasoline stations has been reported with a concern as human carcinogen. Trans, trans-Muconic acid (tt-MA), a metabolite widely used biomarker, is suggested for detection of low benzene exposure. This study aimed to investigate health risk on benzene exposure via biomarker detection and inhaled benzene concentration among gasoline station workers.


The study was conducted among 235 gasoline station workers in Thailand. Spot urine was collected from workers at the end of shift-work and analysed for tt-MA concentration using HPLC. Benzene concentration was measured by personal air sampling and analysed using GC-FID. Additional data was collected by questionnaires and observations. Health risk assessment was performed with applied 5 × 5 risk matrix considering the likelihood of exposure frequency (t,t-MA and benzene level) and severity of adverse symptoms related to benzene toxicity.


Gasoline station workers (85.11%) had experiences of adverse symptoms from mild to severe level. Urinary t,t-MA was detected in 73.62% of workers whereas only 9.25% of them had tt-MA higher than the recommended value (>500 μg/g Creatinine). The risk matrix using tt-MA levels identified worker’s health risk was unacceptable levels (low to high risk; 69.79%). Considering the matrix using benzene concentration which was presented at lower than the occupational exposure level (<0.1 ppm), 65.53% of workers had health risk from that exposure concentration. This semi-quantitative risk assessment showed the significant correlation to the human health risk assessment on benzene exposure following inhalation scenario assessment of U.S.EPA. Those workers (70.67%) had potential lifetime cancer risk higher than acceptable level (>IUR; 2.20E-6).


The finding risk matrix is useful in occupational health surveillance program at gasoline station and for risk control identification. Annual health check-up, monitoring of biomarkers and benzene concentration, and risk communication are necessary to prevent workers adverse health effects and cancer.

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