Prevalence of symptoms associated with occupational exposure to benzene, toluene, ethylbenzene and xylene among gas station workers: a protocol for systematic review and meta-analysis.

Abstract

Gas station workers are at increased risk of inhaling volatile chemical compound vapours that may cause headaches, dizziness, fatigue, eye and nasal irritation, as well as haematological and neurological changes. This systematic review aims to estimate the prevalence of symptoms associated with occupational exposure to benzene, toluene, ethylbenzene and xylene vapours among fuel station workers. The review will be conducted between February and July 2026. Literature searches will be carried out between February and March 2026 across the Medical Literature Analysis and Retrieval System Online (PubMed/MEDLINE), Scopus, Embase, Web of Science, Latin American and Caribbean Health Sciences Literature (LILACS) and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases. Grey literature will be searched using OpenGrey. Eligible studies will include cross-sectional and case-control designs. No language or publication date restrictions will be applied. The systematic review will adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two reviewers will independently select the studies, assess their eligibility using predefined criteria and standardised forms, and extract data. Combined prevalence estimates will be calculated in the meta-analysis using a random effects model with 95% CIs. Risk of bias will be assessed using the Joanna Briggs Institute critical appraisal tool for cross-sectional studies and the Newcastle-Ottawa Scale. Certainty of evidence will be evaluated using the Grading of Recommendations, Assessment, Development and Evaluation approach. RevMan (version 5.3.5) will be used for qualitative and quantitative synthesis. Ethical approval is not required for this protocol, as the review and meta-analysis will be based exclusively on secondary data and will not involve the collection of primary data. Findings will be disseminated through presentations at scientific conferences, publication in peer-reviewed journals, and communication with workers, employers and policy-makers. CRD420251159127.