Benzene exposure from automobiles fuelled with petrol

Abstract

Benzene is a leukaemogenic and mutagenic agent, which may pose a risk to the general public even at low levels of exposure. Since petrol fuel contains a high concentration (1-5%) of benzene, there is the potential for exposure to man during car journeys. The main aim of this study was to develop and validate a sensitive method to detect urinary t,t-muconic acid (uMA) following low level environmental exposures to benzene. Subjects potentially exposed to benzene were divided into petrol (n= 9) and diesel groups (n= 7). The control group (n=14) consisted of individuals who were not exposed to benzene inside the car. The uMA method developed during this study involved butanol extraction instead of the traditional solid phase extraction followed by DV (259nm) detection. The method was reasonably precise (CV=1.5%) with >80% recovery from urIne. Air samples were collected on charcoal tubes and analysed for benzene, toluene, ethylbenzene, and xylenes by GCMS following extraction with purified carbon disulphide. The benzene concentration of ambient air samples taken from inside the cabins of petrol fuelled cars (7.5 ppb) was about triple that found from diesel-fuelled cars (2.6 ppb)(P=O.Ol). The uMA of volunteers exposed to petrol increased (p<0.01) post-sample in compared to pre-exposure level (0.66mgMA/gCr and 0.38mgMA/gCr, respectively). There was no increase in uMA for volunteers exposed to diesel. The uMA level of samples collected from individuals 2h-7h after exposure to petrol showed a significant association with the air benzene (p=0.012) and toluene (p=0.042) concentrations taken inside the car cabins. Half of the 24h-profiles of individuals exposed to petrol had at least one urine with 1 mgMA/gCr or higher, while all of the profiles of controls were below 1 mgMA/gCr. The technique developed in this study for the determination uMA showed promise as a tool for monitoring levels of benzene arising from low-level environmental exposures to petrol.