Hypertension in noise-exposed sawmill workers: a cohort study

¹ University of British Columbia, Canada

^* To whom correspondence should be addressed. E-mail: sbihi{at}interchange.ubc.ca.

Accepted 14 December 2007

	Abstract

Objective: To investigate the hypothesized association between risk of hypertension and exposure to high levels of noise using quantitative exposure assessment and administrative health data.

Methods: We followed a cohort of 10,872 sawmill workers in British Columbia from 1991 to 1998. Subjects were linked with Provincial hospital discharge, outpatient and vital status databases. Cases were males who died, had at least one admission to hospital, or who had three doctor visits within 70 days, for hypertension (ICD9 code 401-405). We used two metric types: cumulative exposure, and duration of exposure above thresholds of 85, 90, and 95dBA. Relative risks were estimated using Poisson regression with low-exposure group as controls and adjusting for age, ethnicity, and calendar period.

Results: 828 cases were identified. The results showed a monotonic increase in hypertension incidence with cumulative exposure, and the risk in the highest exposed population was 32% higher than baseline. Similar results were found using duration of exposure metrics. The highest relative risk was 1.5 in workers exposed for more than 30 years at 85 dBA. Trends were statistically significant.

Conclusions: The risk of hypertension was positively associated with noise exposure above 85 dB.

Keywords: Cohort Analysis, Hypertension, Occupational Noise