소음성 난청은 전형적으로 양측성 난청으로, 초기에는 3, 4, 6 kHz의 청력역치에서 노치(notch), 즉 청력이 급격히 나빠져 V자형 순음청력도로 나타나며 8 kHz 청력은 상대적으로 양호 하다. 반면, 노인성 난청은 전형적인 노치가 없다. 노인성 난청이 없는 소음성 난청은 저주파역에서는 40 dB HL 이하의 경도 난 청을 보이며, 고주파역에서 심한 난청 소견을 보인다. 기간 경과 에 따라 소음성 난청의 진행은 느려지고 노인성 난청의 진행은 가속화된다. 매일 85 dB (A) 이상의 소음에 노출될 경우 노출 강 도가 클수록 소음성 난청의 위험도가 증가한다. 영구적인 청력 역치 변화에 앞서 일시적인 역치 변화가 선행한다(ACOEM, 2012). 소음성 난청으로 생각하기 어려운 순음청력도의 유형으 로는 주파수와 관계없이 편평한 형태의 난청, 고주파보다 저주파 청력이 더 나쁜 경우, 특히 50세 미만의 근로자가 70 dB HL 이상 의 고도 난청 혹은 농일 경우, 청력역치 변화가 매우 심할 때, 좌· 우측 난청의 정도 차이가 매우 클 때를 제시하고 있다(National Hearing Conservation Association, 2011).
Noise-induced hearing impairment is bilateral sensorineural hearing loss that typically occurs with high degrees of hearing impairment in the high-frequency range of 3-6 kHz. Certification of noise-induced hearing impairment as an occupational disease is legislated according to the following criteria: 1) three years of exposure to noise at a level of 85 dB (A); 2) sensorineural hearing loss with no air-bone hearing gap; and 3) hearing loss that is not age-related. In particular, although the direct impact of noise is recognized, it is difficult to distinguish the effects of noise-induced hearing impairment from those of presbycusis. Therefore, recognition of noise-induced hearing impairment and its relevance as an occupational disease may be overlooked. Furthermore, if someone is moved to a noise-free work area [below 85 dB (A)], application for workers’ injury compensation would be disapproved after 3 years because of the expiration of the validity period. However, based on a recent Supreme Court precedent, expiration of the validity period for the right to claim benefits was recently changed to the date of confirmed diagnosis of hearing impairment. This study examines the occupational disease certification criteria for noise-induced hearing impairment and the judgment of occupational diseases. Specifically, we discuss and make suggestions regarding noise exposure standards and assessment methods, used as legal evidence in this area. We also discuss assessments of hearing loss type in order to evaluate the status of noise-induced hearing loss as an occupational disease, and the various issues resulting from occupational hazard claims.
INTRODUCTION REVIEW ON OCCUPATIONAL DISEASE STANDARD OF NOISE-INDUCED HEARING LOSS CONCLUSIONS REFERENCES
