The auditory effects of occupational exposure to chemical solvents.

Abstract

Recently emerging literature indicates that the combination of solvents and noise have the potential to cause auditory dysfunction. There is limited literature available relating to the effects of SIHL exposure on the auditory system and this highlights the need for this study. The study firstly aimed to determine the combined effects of exposure to solvents and noise on auditory function in workers by conducting a systematic review and meta-analysis. The study further aimed at profiling the audiological results of a group of workers exposed to a variety of solvents at various exposure levels within high and low noise factories. A longitudinal prospective research design was used. The researcher collected data at multiple follow-up times over a six month period to obtain multiple measurements on each worker. The final study sample comprised of 12 workers. Results: Aim one: Heterogeneity was assessed in the selected studies by using the I2 test. Results revealed that significantly higher odds (p=0.006) of acquiring hearing loss when workers are exposed to a combination of solvents and noise as opposed to solvents only. Aim two: Participants were exposed to noise and solvents within the limits, however, pure tone threshold results revealed that all workers experienced hearing loss at 12KHz with a mean of 45dB across all the phases. Results for DPOAEs revealed that all workers had reduced amplitudes across all three phases with the exception of one pass result at one phase for one worker. When pure tone thresholds and OAEs were compared, the statistics indicated that there were no significant differences (p=0.68 and p =0.38) between pure tone audiometry and DPOAEs. The sample size of the study was too small to yield significant results. Participants reported on various symptoms experienced from exposure to solvents dizziness, headaches and blurry eyes. The present study supports that exposure to solvents may increase the risk of hearing loss due to noise exposure. The researcher recommends that industries should prioritize noise and solvent reduction to prevent hearing loss and the audiologist‟s role within audiological monitoring of solvent induced hearing loss is emphasized.