The impact of occupation-related noise exposure on hearing thresholds in middle-aged and elderly men: the normative aging study.
Choi-Y; Hu-H; Weisskopf-M; Mukherjee-B; Sparrow-D; Spiro-A; Tak-S; Park-S
Epidemiology 2008 Nov; 19(6)(S):S276-S277
Background: hearing loss is one of the leading health conditions affecting older adults and is associated with a significant impact on disability and mood. Hearing loss occurs for many reasons, of which a major known cause is occupational noise exposure. Research on hearing loss in the general population would benefit from well-validated estimates of occupational noise exposure that can be generated by occupational histories. We used an occupational noise exposure/hearing loss classification system generated by Tak and Calvert (2008) and that takes the form of 5 occupational categories ranked by noise-related adjusted prevalence ratio of hearing difficulty to estimate noise exposure and test its association with audiometrically-measured hearing loss in a well-established longitudinal cohort of men, the Normative Aging Study. Method: the study population consisted of 1011 older adults aged between 44 and 82 years from the Normative Aging Study. We used data on air and bone conduction hearing thresholds measured by pure-tone audiometer (Grason-Stadler 1701) between 1978 and 1993. We classified individuals into five occupation categories designated by Tak and Calvert. We fit linear regression models using dummy variables for the occupation categories and compared hearing thresholds in 0.5, 2, and 4 kHz, using the occupational category a priori associated with the lowest noise-induced hearing loss as the reference category. All models were adjusted for age, education, hypertension, diabetes mellitus, smoking status, and pack-years of cumulative cigarettes. Result: high frequency hearing threshold (at 4k Hz) was significantly associated with higher occupational noise exposure by occupation category (P-value for trend < 0.01). The most problematic occupational category was estimated to have a mean hearing threshold of 4.62 (95%CI: -0.96, 10.2) decibels higher than the lowest occupational category. Conclusion: in this study, hearing thresholds of elderly men were strongly associated with a priori estimates of occupational noise exposure using an ordinal classification system. The effect of occupation-related noise exposure on hearing loss in the general population is significant and measurable. This classification system may prove useful in future studies of hearing loss in the general population, including those trying to disentangle environmental from occupational risk factors.
Work-environment; Exposure-assessment; Exposure-methods; Occupational-exposure; Epidemiology; Biological-factors; Exposure-assessment; Exposure-levels; Statistical-analysis; Workplace-studies; Work-environment; Noise-exposure; Noise-induced-hearing-loss; Noise-sources; Hearing; Hearing-loss; Hearing-threshold; Audiometry; Auditory-system; Age-factors; Surveillance-programs
Epidemiology; ISEE 20th Annual Conference, Pasadena, California, October 12-16, 2008