Exposure assessment of benzene, toluene, and xylene in petrol station attendants: methods, biomarkers, and the case for integrated monitoring: a narrative review

Abstract

Background Petrol station attendants (PSAs) are chronically exposed to benzene, toluene, and xylene (BTX) — hazardous volatile organic compounds present in commercial petrol — through daily fuel dispensing, yet occupational BTX monitoring data, particularly from Low- and Middle-Income Countries (LMICs), remain critically limited. Comprehensive exposure assessment of BTX in occupational settings spans four complementary monitoring approaches, organised here using the Environmental Public Health Paradigm (EPHP) as a conceptual lens: environmental monitoring, personal monitoring, biological monitoring, and biological-effect monitoring. The extent to which published studies have simultaneously applied all four monitoring domains among PSAs remains unknown. Methods A literature search was performed in PubMed, Medline, and Google Scholar for original articles published from January 1992 to December 2024. This narrative review considered studies reporting data on at least one of the four monitoring domains among PSAs or comparable petrol sector workers. Results Environmental and personal monitoring document elevated BTX concentrations at refuelling sites — frequently exceeding international occupational exposure limits (OELs) in LMIC settings — with benzene concentrations ranging from 0.1 to over 6 ppm across reviewed studies. Biological monitoring confirms systemic benzene absorption, with urinary S-phenylmercapturic acid (SPMA) and urinary benzene (U-BEN) emerging as the most sensitive and specific biomarkers. Biological-effect monitoring documents consistent genotoxicity, haematotoxicity, oxidative stress, and immunological disruption in PSA populations globally. To our knowledge, no published study identified in this review has simultaneously implemented all four monitoring domains in a single PSA cohort. Conclusion BTX exposure among PSAs constitutes a significant and underaddressed occupational health problem, with a disproportionate burden in LMICs. The absence of integrated multi-domain monitoring evidence limits the development of evidence-based occupational health policy for this vulnerable workforce. Future studies combining all four monitoring domains in a single, well-characterised cohort are recommended.