[Hearing function and solvent exposure: study of a worker population exposed to styrene]

Area of Science:

• Occupational health
• Audiology
• Toxicology

Context:

• Occupational styrene exposure is common in industries like fibreglass reinforced plastic boat manufacturing.
• Previous research suggests potential ototoxicity of styrene, but often confounded by noise exposure.
• This study isolates styrene exposure to assess its independent effects on hearing.

Purpose:

• To investigate the ototoxic effects of occupational styrene exposure in the absence of other risk factors.
• To compare pure-tone audiometric thresholds between styrene-exposed workers and a control group.
• To determine if styrene alone can cause sensorineural hearing loss.

Summary:

• 32 workers exposed to styrene (mean urinary mandelic + phenylglyoxylic acid 149 mg/g crea) were compared to 60 unexposed controls.
• Exposed workers showed statistically significant (p < 0.05), albeit slight, higher audiometric thresholds across most tested frequencies (0.5-6 KHz) compared to controls.
• Hearing impairment was a weak, high-frequency sensorineural hearing loss, not significantly limiting social hearing.

Impact:

• Findings suggest styrene exposure alone can lead to a subtle high-frequency hearing deficit.
• The observed hearing loss is unlikely to have significant social or legal medical implications.
• Further research with larger sample sizes and objective diagnostic tests is recommended to confirm these findings.