An assessment of exposure to benzene, toluene and xylene in a group of South African petroleum refinery workers.

Abstract Biomonitoring of exposure to benzene, toluene and xylene (BTX) was conducted in a group of 29 petroleum refinery workers in South Africa. Post shift urine samples from 21 males and 8 females over a period of four years (2010 to 2013 inclusive) were received from one petroleum refinery. The samples were analysed using high performance liquid chromatography with diode array detection and liquid-liquid extraction followed by gas chromatography-mass spectrometry for phenol, o-cresol and methylhippuric acid which are biomarkers of exposure to benzene, toluene and xylene, respectively. Benzene and xylene results were well within the recommended exposure levels with the exception of one worker in 2013 with an elevated phenol exposure level. A few workers (< 40%) were found to be randomly overexposed to toluene, with 17% of the workers exhibiting higher than the biological exposure index. No difference was observed in exposure with regard to age and gender (p>0.05), except in 2012 where females were more exposed to benzene than their male counterparts (p=0.003). Differences in exposure were found among the three exposure categories (low, medium and high exposure), for both xylene and benzene exposure in 2010 and 2011, respectively. Friedman’s ANOVA showed that over the four years of monitoring, the workers were exposed to variable levels of BTX (p < 0.05). Random individual overexposure to toluene and an anomaly for benzene were noted. Biomonitoring of petroleum workers and proper assessment of the health risks and planning for adequate health protection are highly recommended for this group of workers.