Occupational Styrene Exposure on Auditory Function Among Adults: A Systematic Review of Selected Workers

Abstract

A review study was conducted to examine the adverse effects of styrene, styrene mixtures, or styrene and/or styrene mixtures and noise on the auditory system in humans employed in occupational settings. The search included peer-reviewed articles published in English language involving human volunteers spanning a 25-year period (1990–2015). Studies included peer review journals, case–control studies, and case reports. Animal studies were excluded. An initial search identified 40 studies. After screening for inclusion, 13 studies were retrieved for full journal detail examination and review. As a whole, the results range from no to mild associations between styrene exposure and auditory dysfunction, noting relatively small sample sizes. However, four studies investigating styrene with other organic solvent mixtures and noise suggested combined exposures to both styrene organic solvent mixtures may be more ototoxic than exposure to noise alone. There is little literature examining the effect of styrene on auditory functioning in humans. Nonetheless, findings suggest public health professionals and policy makers should be made aware of the future research needs pertaining to hearing impairment and ototoxicity from styrene. It is recommended that chronic styrene-exposed individuals be routinely evaluated with a comprehensive audiological test battery to detect early signs of auditory dysfunction.

New trends in the prevention of occupational noise-induced hearing loss

“…This variability is attributed to several factors other than these included in the ISO model, such as coexposure to ototoxic substances (organic solvents, ototoxic drugs), heredity (gene polymorphisms), and several determinants of individual susceptibility to noise, such as an increased level of lipids, metabolic diseases (diabetes), hypertension, as well as habits (cigarette smoking) [30]. The results of recent systematic review papers call for an urgent implementation of hearing protection standards for workers exposed to organic solvents, such as styrene, toluene and mixtures of solvents, particularly in the case of combined exposures to these chemicals and noise [31,32]. As a consequence of studies on organic solvents, the updated European Directive 2003/10/EC [33] stipulates that employers should estimate the risk of hearing impairment due to exposure to organic solvents in co-exposure with noise.…”

Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update

“…More recently, a weight-of-evidence-based review of animal and human epidemiological evidence for ototoxicity of styrene concluded that, although the human data were less clear than animal data in terms of establishing a doseresponse relationship, the overall evidence favors the conclusion that styrene is ototoxic (Vyskocil et al 2012). Similarly, while recognizing the complications imposed by multiple confounding factors (including exposure to noise and/or other chemicals as well as age and sex) a 2017 systematic review recommended that chronic styreneexposed workers be routinely evaluated with a comprehensive audiological test battery to identify early signs of hearing impairment (Pleban, Oketope, and Shrestha 2017).…”

Wearable Sensor-Based Monitoring of Environmental Exposures and the Associated Health Effects: A Review

“…Meanwhile, noise exposure can damage the human cardiovascular system, autonomic nervous system, endocrine system, and neurocognitive functioning [ 9 ]. Extreme environmental temperatures significantly increase the risks of cardiovascular diseases [ 10 ], neurodegenerative diseases [ 11 ], depression [ 12 ], and anxiety [ 13 ]. In addition, illumination and light can impact human cognitive functions [ 14 ].…”