Occupational noise exposure and the risk of hypertension.

Background: Noise may increase the risk of hypertension, but findings are inconsistent with respect to both community and occupational noise exposure. We used a large sample of noise-exposed industrial trades to analyze the association of occupational noise exposure and the risk of hypertension.
Methods: The 7-year prospective cohort study included 145,190 workers from 625 companies representing 10 industrial trades and 100 companies from the finance sector. They were followed from 2001 to 2007 by record linkage with several Danish national registries. Full-shift noise exposure levels, measured in a random subset of 710 workers at the start and the end of follow-up, ranged from 70 to 86 dB(A); based on this information, historical levels back to the 1960s were estimated. Hypertension (defined by the prescription of antihypertensive medication or a hospital discharge diagnosis of hypertension) was regressed on the trade mean sound levels (LAEq) adjusting for a number of covariates.
Results: Women had increased rate ratios for hypertension when comparing blue-collar industrial workers with white-collar financial workers (adjusted rate ratio = 1.17 [95% confidence interval = 1.09-1.26]). For men, the corresponding relative risk value was 1.06 (0.98-1.14). Within blue-collar industrial workers, however, increasing noise exposure level was not associated with an increasing risk of hypertension among either men or women.
Conclusion: Our study shows no increased risk of hypertension with exposure to noise in the lower half of the 80-90 dB(A) range.