Low-level Occupational Exposure to BTEX and Dyschromatopsia: A Systematic Review and Meta-analysis


Purpose: The present study aimed to assess whether occupational exposure to low concentrations of benzene, toluene, ethyl benzene, and xylene (BTEX) is associated with color vision impairment.

Methods: We queried the PubMed, Scopus, Embase, Web of Science, and ProQuest as the main databases, as well as grey literature such as Google scholar. A random-effects model was used to assess relative risk. A funnel plot was created to assess publication bias. Meta-regression analysis was applied to identify variables that explain the between-study variation in the reported risk estimate.

Results: An overall standardized mean difference of 0.529 (95% CI:0.269, 0.788; p<0.0001) was obtained in the random-effects model, which was corresponded to a medium-size effect. Duration and the levels of exposure to benzene, toluene, and xylene were the significant predictors of the magnitude of the combined risk estimate. Chronic exposures to low levels of BTEX was associated with dyschromatopsia determined by the color confusion index.

Conclusions: The impairments can occur even at exposures lower than the occupational exposure limits of BTEX. However, there are several flaws in the determination of workers’ exposure, which did not allow to establish how low the level of these chemicals can cause color vision impairment.

Authors: Younes Sohrabi, Fatemeh Rahimian, Esmaeel Soleimani, Soheil Hassanipour
; Full Source: International journal of occupational safety and ergonomics : JOSE 2022 Dec 10;1-29. doi: 10.1080/10803548.2022.2157543.