Audiometry and exposure measurements were conducted on workers from fiberglass and metal products manufacturing plants and a mail distribution terminal (N = 313). Workers exposed to noise and styrene had significantly worse pure-tone thresholds at 2, 3, 4, and 6 kHz when compared with noise-exposed or nonexposed workers. Age, noise exposure, and urinary mandelic acid (a biologic marker for styrene) were the variables that met the significance level criterion in the multiple logistic regression. The odds ratios for hearing loss were 1.19 for each increment of 1 year of age (95% confidence interval [CI], 1.11-1.28), 1.18 for every decibel >85 dB(A) of noise exposure (95% CI, 1.01-1.34), and 2.44 for each millimole of mandelic acid per gram of creatinine in urine (95% CI, 1.01-5.89). Our findings suggest that exposure to styrene even below recommended values had a toxic effect on the auditory system.

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.

The beliefs and attitudes regarding the risk of hearing loss and their impact on hearing protector use were investigated among Swedish workers. A questionnaire, developed by the US National Institute for Occupational Safety and Health (NIOSH), was used. The study objective was to assess workers' attitudes towards using hearing protection devices (HPDs) and to enhance the ability of workers to protect themselves from occupational hearing loss. Ninety-five per cent of the respondents were aware that loud noise could damage their hearing, 90% considered that a hearing loss would be a serious problem, and 85% believed that HPDs could protect their hearing. However, lower percentages of workers always used the HPDs when they were noise-exposed. Fifty-five per cent of the workers indicated that they could not hear warning signals when using HPDs, and 45% of the workers indicated that they considered HPDs to be uncomfortable. These issues must be addressed to make HPD use more effective.