Personal Exposure to Benzene and 1,3-Butadiene during Shutdown at a Swedish Refinery

Abstract

Workers in the refinery industry are exposed to a mixture of hydrocarbons, including benzene and 1,3-butadiene which are human carcinogens. The aim of this study was to measure the exposure to benzene and 1,3-butadiene among workers during shutdown for routine maintenance and repair work at a Swedish refinery. Full-shift personal measurements were performed among refinery workers during two shutdowns (one complete and one partial) at one refinery. Measurements were conducted among occupational groups a priori considered to be highly exposed during the initial phase of the two shutdowns. The exposure to benzene and 1,3-butadiene were measured using Perkin Elmer diffusive samplers filled with Carbopack X. The compounds were determined by an automatic thermal desorber connected to a gas chromatograph and mass spectrometer detector. A total of 48 measurements were carried out, 26 during complete and 22 during partial shutdown. At the complete shutdown the geometric and arithmetic mean benzene exposure was 0.23 mg/m3 and 0.96 mg/m3, respectively (range 0.01-4.5 mg/m3). Six samples exceeded the Swedish occupational exposure limit (OEL) of 1.5 mg/m3 for benzene. Benzene exposure was generally lower during the partial shutdown due to lower content of benzene in the product (geometric mean 0.05 mg/m3, range 0.01-1.1 mg/m3). Overall, the exposure to 1,3-butadiene was far below (range <0.001-0.04 mg/m3 ) the OEL value of 1 mg/m3. During shutdown of the refinery, the workers were exposed to higher levels of benzene than during normal production. Tasks that contributed to higher exposure levels were work performed in an area with catalytic treatment of benzene rich petroleum products, especially working with spading of the process unit, and open drainage of benzene rich petroleum products to the sewage. In conclusion, there is a relatively high risk of increased exposure to benzene during shutdown of the refinery, and protective equipment should be used during some tasks.