Audiological findings in workers exposed to styrene alone or in concert with noise

Abstract

Audiological testing, interviews and exposure measurements were used to collect data on the health effects of styrene exposures in 313 workers from fiberglass and metal-product manufacturing plants and a mail terminal. The audiological test battery included pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), psychoacoustic modulation transfer function, interrupted speech, speech recognition in noise and cortical response audiometry (CRA). Workers exposed to noise and styrene had significantly poorer pure-tone thresholds in the high-frequency range (3 to 8 kHz) than the controls, noise-exposed workers and those listed in a Swedish age-specific database. Even though abnormalities were noted on DPOAE and CRA testing, the interrupted speech and speech recognition in noise tests were the more sensitive tests for styrene effects. Further research is needed on the underlying mechanisms to understand the effects of styrene and on audiological test batteries to detect changes in populations exposed to solvents.

Chemical exposure and hearing loss

“…Several clinical and epidemiological studies confirmed an association between exposure to solvents (styrene, toluene, xylenes, solvent mixtures, and jet fuels) in the workplace and increased prevalence of hearing loss, as well as poor hearing thresholds beyond the traditional 4 kHz noise-related audiometric notch. [83][84][85][86][87][88][89][90][91][92] For an extensive review of human studies, see Johnson and Morata 93 (available online at https:// gupea.ub.gu.se/handle/2077/23240).…”

Perda auditiva associada à exposição ocupacional a solventes orgânicos: uma revisão sistemática

“…The study by Johnson et al 21 showed changes in both the peripheral auditory pathway, with BAEP results indicating damage to the organ of Corti (inner ear), and CANS. Differences were observed between the findings obtained for individuals exposed to styrene and normality scores for the ACR and speech-in-noise tests.…”

“…Focused on the plastic and fiberglass industries, six studies found a positive association between exposure to styrene and Hearing Loss (HL) 11,[20][21][22][23][24] , four of which featured styrene exposure levels below recommended limits [20][21][22][23] . The worst PTA responses for a wide range of frequencies (0.25 -8 kHz) were found among individuals of the group exposed to the solvent [22][23][24] .…”

Extraction of Cochlear Non-linearities with the Bispectral Analysis

“…In literature, evidences that exposure to organic solvents (e.g., styrene) either alone or in combination with noise has ototoxic effects, have been largely described [7,[17][18][19]. In these last studies, the effect of styrene exposure was investigated with a complete set of auditory tests, including pure tone audiometry [17,19], speech recognition tests [18], and OAE-based tests [7], to estimate the damage at the level of the cochlear outer hair cells (OHCs).…”

“…In these last studies, the effect of styrene exposure was investigated with a complete set of auditory tests, including pure tone audiometry [17,19], speech recognition tests [18], and OAE-based tests [7], to estimate the damage at the level of the cochlear outer hair cells (OHCs).…”