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KMID : 0858620020060020095
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Korean Journal of Audiology
2002 Volume.6 No. 2 p.95 ~ p.110
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Audiologic Effects of Hazardous Factors in Shipyard Workers
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Kim Kyoo-Sang
Kim So-Yeon
Lee Na-Roo
Lee Jeong-Oh
Ko Kyung-Seon
Cheong Ho-Keun
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Abstract
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Objectives: The importance of the association between advancing age and hearing loss is well recognized. Further, prolonged significant noise exposures are also known to result in permanent hearing loss. However, little is known of the contribution of industrial chemical exposures to hearing loss. The purpose of this study was to assess whether industrial chemical exposures cause hearing loss in the groups of workers in the shipbuilding manufacturing industries.
Methods: The study group comprised 440 workers exposed to various levels of noise and chemicals. Data on work history, medical history, present health, occupational and nonoccupational exposures to noise or chemicals, and life-style factors were collected through an interview. The participants underwent pure-tone audiometry and immittance audiometry testing. Their exposures to noise and chemicals were assessed. Altogether 440 subjects were divided into the following four groups：managers with no risk due to noise or chemical exposure at the workplace, shipfitters exposed to noise only, painters exposed to organic solvents only, and welders exposed to both noise and metals.
Results: The noise level was the highest in grinding (94.9 dBA), and followed by shipfitting (90.5 dBA), welding (86.4 dBA), and painting (83.6 dBA). However, the concentration of chemicals was below the occupational exposure limits for most of the subjects. Hearing thresholds were significantly poorer for groups exposed noise and chemicals, when compared with the reference group. The hearing thresholds at frequencies of 4~8 kHz were poorer for shipfitters exposed to high noise than for the chemicals exposed groups. However, the mean hearing thresholds at frequencies of 0.5~2 kHz were the highest in the welders group. Also, hearing thresholds increased significantly in the workers who was older age, and who was longer work duration. In the multiple regression analysis, age, work duration, work type related to the noise and chemicals exposure, and military service backgrounds as to the noise exposure were independently associated with hearing thresholds at PTA, 4 and 8 kHz.
Conclusions: The results suggest that the probable combined effects of chemicals and noise on hearing should be considered even when the exposures are within the occupational exposure limits. The results of the study show that exposure to chemicals may create a significant risk of hearing impairment. Therefore, further steps should be taken to include the exposed population into effective preventive programmes.
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KEYWORD
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Hearing threshold, Noise, Shipyard, Chemicals, Work type
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