The effects of occupational exposure to noise and solvents on hearing loss among rotogravure printing workers were examined. Personal breathing zone samples were collected from 124 workers and analyzed for toluene (108883), ethanol (64175), and ethyl-acetate (141786). Urine samples obtained from 109 workers were analyzed by gas chromatography for hippuric-acid content. Airborne solvent levels ranged from below 0.25 to 1,240mg/m3 for ethanol, from 1.1 to 2,635mg/m3 for ethyl-acetate, and from 0.14 to 919mg/m3 for toluene. The exposure index for toluene exceeded unity in the engraving and rotogravure printing departments. Of the 109 workers with urine samples, 8% had urinary hippuric-acid concentrations exceeding the recommended biological exposure index (BEI) for toluene of 2.5 grams of hippuric-acid per gram of creatinine. Noise levels, determined using noise dosimeters, were highest in the printing and paint preparation departments. Otoscopy, pure tone audiometry, and immittance audiometry were used to test workers for hearing loss. Most of the workers did not use appropriate hearing protection. Of the workers who reported tinnitus, 75% had the highest noise exposures. The prevalence of bilateral high frequency sensorineural hearing loss among the workers was 49.2%. Based on stepwise logistic regression analysis, age, tenure, airborne solvent levels, noise exposure levels, urinary hippuric-acid concentration, and a history of ear infections were included in the model for predicting hearing loss. The most significant risk factor for hearing loss was the BEI for toluene, with an odds ratio (OR) of 1.76. Age was also a significant predictor of hearing loss, with an OR of 1.07. The authors conclude that occupational exposure to toluene induces hearing loss.
NIOSH-Author; Occupational-exposure; Printers; Industrial-noise; Hearing-loss; Noise-exposure; Noise-levels; Dosimetry; Organic-solvents; Age-factors; Urinalysis; Risk-factors; Hearing-tests; Air-samples;
Author Keywords: biological monitoring; ethanol; ethyl acetate; hippuric acid; interaction; noise