Occupational benzene exposure and risk of nervous system cancers: A systematic review and meta-analysis

Background: Benzene is a solvent that has played a significant role in various industries and applications over time, but its use declined due to its carcinogenic nature. Classified as a human carcinogen since 1979, benzene exposure is linked to leukemia and possibly other cancers. The global rise of nervous system cancers urges investigation into the possible role of benzene. Our aim is to investigate this association through a systematic review and meta-analysis of occupational cohort and case-control studies. Methods: We registered our study protocol and followed established guidelines (Registration No. CRD42022379720). A systematic search across databases yielded 36 independent cohort and case-control studies. We conducted a random-effects meta-analysis of relative risks (RR) for nervous system cancers. Analyses were stratified based on various factors such as region, study design, and exposure level. Publication bias was evaluated using a funnel plot and Egger test. Results: Our meta-analysis indicates an association between benzene exposure and risk of overall nervous system cancers (RR = 1.21, 95 % confidence interval [CI] = 1.05–1.38). Stratified analyses showed an association with glioma (RR = 3.88, 95 % CI = 1.33–11.31, N risk estimates=2). Publication bias was detected (p = 0.01). Conclusion: Our study found an association between occupational benzene exposure and increased risks of nervous system cancers, which however cannot be interpreted as causal. While these findings highlight the need for stringent safety measures, they also reveal gaps in literature. Further research is essential to address these limitations and deepen our understanding of benzene's health implications.