Hearing Loss in the Workers Exposed to Organic Solvents and Noise

유기용제와 소음에 폭로된 근로자들의 청력 손실

The purpose of this study was to evaluate the effect of organic slovents and noise on hearing loss. We selected organic solvents exposed group of 32 cases, noise exposed group of 31 cases, both noise and solvent exposed group of 31 cases, and control group of 53 cases and studied the relation between exposure level of noise and organic solvents and degree of hearing loss. The results were as follows. The subjects under investigation were exposed to noise and organic solvents under threshold limit values and the amount of urinary hippuric acid excretion were also under biological exposure indices. In case of noise, both noise and organic solvents exposed group and noise exposed group were more exposed than organic solvents exposed group(p<0.05). When urinary hippuric acid excretion were concerned, both noise iud organic solvents exposed group and organic solvents exposed group showed higher values than noise exposed group(p<0.05). In comparison of mean auditory threshold values by frequency, on the air conduction test, both noise and organic solvents exposed group showed significantly higher hearing loss than noise exposed group in 500Hz of right ear, 500 and 2000Hz of left ear(p<0.05). Forty-three cases among 147 subjects were regarded as hearing loss group and average age(42.6years) of hearing loss group was higher than normal groups average age of 38.0 years. Urinary hippuric acid excretions of hearing loss group were significantly higher than normal group(p<0.05). Thirty-eight percent(12cases) of noise exposed group, 40.6 $\%$(13cases) of organic solvents exposed group, 51.6 $\%$(16cases) of both noise and organic solvents exposed group, and 3.8 $\%$(2cases) of unexposed group were regarded as hearing losers. Exposed groups showed higher incidence of hearing loss than unexposed group but there were no significant differences among the exposed groups. The variables showing significant correlation with hearing loss were age and the amount of hippuric acid in urinary excretion. When age were adjusted for the purpose of seeing the effects of hearing losses due to organic solvent, urinary excretion of hippuric acids was the only variable with significant correlation with hearing loss (p<0.05). When odds ratio to hearing loss between control and exposed groups was considered, noise exposed group showed 6.1 times (95 $\%$ CI: 3.3-8.7), organic solvents exposed group showed 7.4 times (95 $\%$ CI: 3.5-14.6) and both noise and organic solvents exposed group showed 17.2 times(95% CI: 5.6-31.8) higher values than unexposed group(p<0.01). Above results suggest that health screening test of hearing loss is also needed in organic solvents exposed workers.

유기용제와 소음의 폭로가 청력손실에 미치는 영향을 알아보기 위해 유기용제 폭로군 32명, 소음 폭로군 31명, 소음과 유기용제에 동시에 폭로된 군 31명 그리고 대조군 53명을 대상으로 소음과 유기용제 폭로 정도와 청력손실치를 계산하여 얻어진 결과는 다음과 같다. 1. 조사 대상자들은 소음과 유기용제에 허용기준치 이하로 폭로되었으며, 요중 마뇨산 배설량도 참고치 이하로 배설되었다. 소음의 경우 소음과 유기용제 동시 폭로군과 소음 폭로군이 유기용제 폭로군보다 높았으며(p<0.05) 요중 마뇨산은 소음 유기용제 동시폭로군과 유기용제 폭로군이 소음폭로군보다 배설량이 더 많았다(p<0.05). 2. 주파수별 기도청력은 소음과 유기용제 동시 폭로군이 소음군보다 우측귀의 500Hz, 좌측귀의 500, 2000Hz에서 유의하게 더 높은 청력손실치를 나타내었고(p<0.05), 유기용제군과의 비교시에는 왼쪽귀 4000Hz에서 청력손실이 유의하게 더 높았다(p<0.05). 3. 조사 대상자 147명중 43명이 청력손실군에 해당되었으며 청력손실군의 연령이 42.6세로 정상군 38.0세 보다 더 높았으며 요중마뇨산 배설량도 유의하게 더 많았다(p<0.05). 4. 청력손실자는 소음군에서는 대상자의 38.7 $\%$(12명), 유기용제군 40.6 $\%$(13명), 소음과 유기용제 동시폭로군은 51.6 $\%$ (16명), 그리고 비폭로군은 3.8 $\%$(2명)의 빈도를 보였으며 비폭로군에 비해 폭로군에서 청력손실자가 많이 발생하였으나 폭로군 사이에서는 유의한 차이를 보이지 않았다. 5. 청력손실과 유의한 상관관계를 보이는 변수는 연령과 요중마뇨산 배설량이었으며, 유기용제로 인한 청력손실의 영향을 보기위해 연령을 보정하였을 때는 요중마뇨산 배설량만이 상관관계를 보였다(p<0.05). 6. 대조군과 폭로군사이의 청력손실에 대한 교차비에서는 비폭로군에 비해 소음폭로군은 6.1배(95 $\%$ CI,: 3.3-8.7),유기용제 폭로군은 7.4배(95 $\%$ CI,: 3.5-14.6) 그리고 동시폭로군은 1$\ulcorner$.2배(95 $\%$ Cl,: 5.31.8)로 더 켰다(p<0.01). 이상의 결과로 볼 때 유기용제 폭로 근로자에 대해서도 청력장애에 대한 건강진단이 실시되어야 할 것으로 생각된다.