Occupational noise exposure and ischemic heart disease: a pooled analysis of six Nordic cohorts

OBJECTIVES: This study aimed to investigate the impact of occupational noise exposure on incident ischemic heart disease (IHD), including acute myocardial infarction (AMI). METHODS: We conducted a pooled analysis of six Nordic cohorts with a total of 83 103 participants with individual and area-level confounder information. Occupational codes were matched to a job-exposure matrix developed from Swedish measurements in five categories (LAeq8h): <70, 70-74, 75-79, 80-84, and ≥85 dB(A). Residential address history was used to estimate baseline 1-year average residential road traffic noise exposure. Data on incident IHD and AMI were obtained from national patient registers. We calculated hazard ratios (HR) using Cox proportional hazard models adjusted for socioeconomic and lifestyle factors. RESULTS: After adjustment for baseline year, sex, marital status, area-level income, education, smoking, and physical activity, exposure to ≥85 dB(A) of occupational noise was associated with an 10% and 12% increased risk of IHD, excluding angina pectoris, and AMI, respectively. For these outcomes, suggestive exposure-response trends were observed, but risks were only statistically significant for those exposed to ≥85 dB(A) as well as men exposed to ≥75 dB(A). We did not find evidence that combined exposure to both occupational noise and road traffic noise was particularly harmful. CONCLUSION: We found increased risks of IHD and AMI among those exposed to occupational noise ≥85 dB(A). Further studies should investigate whether this association is confounded by other occupational exposures.