The risk of hearing loss associated with occupational exposure to organic solvents mixture with and without concurrent noise exposure: A systematic review and meta-analysis.

This study is a meta-analysis of the previous epidemiological studies which investigated the quantitative estimates of the association between independent or combined exposure to noise and mixed organic solvents and hearing loss until October 2014. Overall, 15 studies with information on 7530 individuals (6% female) were included. Having assessed - by puretone audiometry - the adjusted odds ratio estimates for the association between solvents mixture exposure and the risk of developing hearing loss stood at 2.05 (95% confidence interval (CI): 1.44-2.9). Similarly, for subjects who were concurrently exposed to noise and solvents mixture, an OR of 2.95 (95% CI: 2.1-4.17) was obtained. There was some evidence of heterogeneity within each of the 2 exposure groups (p heterogeneity < 0.001). This heterogeneity was not explained by differences in strength of effect between duration of exposure, the number of solvent and exposure index in subgroups of solvents mixture exposure. Based on the available data, our analysis has provided the evidence of increased risk of developing hearing loss for workers exposed to organic solvents even at quite low concentration. Moreover, if such exposure is accompanied by noise, it will exacerbate the extent of hearing loss. Int J Occup Med Environ Health 2017;30(4):521-535.