Annals of Occupational and Environmental Medicine

Original Article

The Effect of Noise Exposure and Age on the Changes of Group Mean Hearing Threshold Level: Annual Follow-up Studies for Seven Years: Ji Ho Lee, Choong Ryeol Lee, Cheol In Yoo, Seung Rim Yaang, Ok Hyun Kim, Byung Mann Cho, Su Ill Lee, Don Kyoun Kim; Korean Journal of Occupational and Environmental Medicine 1999;11(2):137-152. Published online June 30, 1999; DOI: https://doi.org/10.35371/kjoem.1999.11.2.137

This study was carried out to evaluate the effect of noise exposure and age on the changes of group mean hearing threshold level(HTL) over 7-year period. For this purpose, consecutive annual audiometric tests were performed from 1991 to 1997. among 718 male employees of a metal product manufacturing factory. The subjects were divided four groups as follows according to noise level category(NLC). NLC-I officer, exposed noise level was under 60 dB(A) of time weighted average(TWA) NLC-JI technical assistant or engineer, they exposed to workplace noise occasionally NLC-IJJ worker, exposed noise level was below 85 dB(A) of TWA. wore hearing protection device(earmuff or earplug) NLC-IV worker, exposed noise level was over 85 dB(A) of TWA, wore hearing protection device(earmuff and earplug). The results were as follows 1. The improvement of group mean HTL was continued until the fifth year, showing the peak at the third year. The magnitudes of this learning effect were 1.5 - 4.6 dB. 2. The mean HTL of each age group tended to increase after the third year and the tendency was more prominent at 4000 Hz. 3. In noise exposed group(NLC-II, III, and IV), mean HTL increased from the third year after decreasing, meanwhile, in noise free group(NLC-I). it was few changed for the entire period. Among the noise exposure group, the mean HTL of NLC-IV was lower than that of NLC-III and NLC-IV. 4. After learning effect, the mean increase of HTL in noise free group(NLC-I) was 0.4-1.7 dB that suggests aging effect, and that in noise exposure group(NLC-ll, III, and IV) was 0.9 -4.1 dB that suggests noise effect. 5. Statistical analysis of the general linear model implicated that the effect of age was statistically significant at 500, 3000, 4000 and 6000Hz. and the effect of noise exposure was statistically significant at all frequencies except 6000Hz. However, the age * noise interaction was not significant at all frequencies. From these results, it was concluded that the effect of age and noise exposure seems to affect the mean HTL independently and these two factors contribute to an additive effect for the mean HTL change. Furthermore, more concerns should be needed for hearing conservation of low level exposures without any specific protection.

Citations

Citations to this article as recorded by

For 5-years the Longitudinal Study on the Effect of Noise Exposure and Aging to the Changes of Hearing Threshold Level
Chang Ho Chae, Ja Hyun Kim, Jun Seok Son
Journal of Korean Society of Occupational and Environmental Hygiene.2015; 25(4): 573. CrossRef
Prevalence and Risk Factors of Hearing Loss Using the Korean Working Conditions Survey
Kyoo Sang Kim, Oh Jun Kwon
Korean Journal of Audiology.2012; 16(2): 54. CrossRef
Cohort study for the effect of chronic noise exposure on blood pressure among male workers in Busan, Korea
Ji Ho Lee, Weechang Kang, Seung Rim Yaang, Nari Choy, Choong Ryeol Lee
American Journal of Industrial Medicine.2009; 52(6): 509. CrossRef

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Original Article

RELATED FACTORS OF DIAGNOSIS OF CHRONIC CARBON DISULFIDE POISONING: Byung Sung Kim, Hyun Rim Choi, Chang Won Won; Korean Journal of Occupational and Environmental Medicine 1997;9(1):1-11. Published online February 28, 1997; DOI: https://doi.org/10.35371/kjoem.1997.9.1.1

Abstract PDF

The purpose of this study was to compare the characteristics between chronic CS2 poisoning group and non-poisoning group, to find out major factors for decision of chronic CS2 poisoning, to describe the characteristics of cerebral infarctions, and to find out the related factors of cerebral infarctions. The study subjects were 220 ex-employees from W company and the study period was from August, 1993 to November, 1995. The proportion rate of chronic CS2 poisoning was higher in older age groups and longer work duration groups. The rate differed by cerebral infarction, microaneurysm, other retina lesions, polyneuropathy, psychiatric lesions, and sensorineural hearing loss. The cerebral infarction was found to be mainly multiple and the frequently occurred locations were periventricular white matter, frontal lobe and basal ganglia. The logistic regression for chronic CS2 poisoning showed that the major factors were microaneurysm, cerebral infarction, polyneuropathy, other retina lesions, diastolic blood pressure, and sensorineural hearing loss. Among the approved group 117 patients were followed up continuously at the outpatient clinic, 62.4% of the patients had hypertension, 61.5% had polyneuropathy, 52.1% had cerebral infarction, 35.0% had hyperlipidemia, 29.9% had liver disease, 15.4% had psychiatric diseases, 6.0% had angina, and 4.3% had anemia. For the hypertensive patients, 1.9 kinds of antihypertensive drugs were needed to control the blood pressure, and the BP decreased from 164/101 mmHg to 131/81 mmHg.

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Occupational Risk Factors for Stroke: A Comprehensive Review
Munyoung Yang, Hyoungseob Yoo, Seo-Young Kim, Ohwi Kwon, Min-Woo Nam, Kwang Hyun Pan, Mo-Yeol Kang
Journal of Stroke.2023; 25(3): 327. CrossRef
Occupational exposure to neurotoxic substances in Asian countries – Challenges and approaches
Monika Meyer-Baron, Eun A. Kim, Iman Nuwayhid, Gaku Ichihara, Seong-Kyu Kang
NeuroToxicology.2012; 33(4): 853. CrossRef
Work-related Cerebro-Cardiovascular Diseases in Korea
Dae-Seong Kim, Seong-Kyu Kang
Journal of Korean Medical Science.2010; 25(Suppl): S105. CrossRef
Occupational Neurological Disorders in Korea
Eun-A Kim, Seong-Kyu Kang
Journal of Korean Medical Science.2010; 25(Suppl): S26. CrossRef

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Original Article

The Changes of Hearing Threshold Level in Noise-exposed Workers: Byung Mann Cho, Jong Ook Park; Korean Journal of Occupational and Environmental Medicine 1994;6(1):32-41. Published online February 28, 1994; DOI: https://doi.org/10.35371/kjoem.1994.6.1.32

Abstract PDF

Using audiometric test data, noise exposed workers were followed up to assess the activities for hearing conservation from 1989 to 1992. The subjects of study were 71 workers who could be followed up at least two years during this follow-up period. In all subjects, increasing trend of hearing threshold levels (HTLs) was observed after three years of follow-up at all testing frequencies in audiometry and this increase was statistically significant at 8KHz(p<0.05). Also, HTLs increased significantly(p<0.05) in the workers who complained tinnitus(at 0.25, 8KHz), who ws below 90 dB (at 8KHz). Effectiveness of the activities for hearing conservation, assessed by sequential test-retest comparisons, was lower in the workers who complained tinnitus, who had past history of ear disease, and whose workplace noise level was below 90 dB. These findings suggest that the activities for hearing conservation at workplace may have been unsatisfactory until now and more stringent measures may be necessary, especially in the workers who complain tinnitus, who have past history of ear disease, and whose workplace noise level is below 90dB.

Citations

Citations to this article as recorded by

For 5-years the Longitudinal Study on the Effect of Noise Exposure and Aging to the Changes of Hearing Threshold Level
Chang Ho Chae, Ja Hyun Kim, Jun Seok Son
Journal of Korean Society of Occupational and Environmental Hygiene.2015; 25(4): 573. CrossRef

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