The impact of occupational noise exposure on blood pressure

Introduction
Noise has an effect on the endocrine system and autonomic nervous system, which may adversely affect the cardiovascular system. We investigated the association between occupational exposure to noise and systolic (SBP) and diastolic (DBP) blood pressure in workers.

Methods
Data of 205 737 Belgian employees obtained during occupational health surveillance in 2009 were analysed. The employees were divided in 2 groups: exposure < 80 DB (83,6%) and ≥ 80 DB (16,6%). Differences in SBP and DBP were observed, before and after correction for potential differences in age, gender and BMI. Data were analysed using SPSS.

Results
T-tests showed a statistically significant difference (p<0,05) between the exposure groups for both SBP (mean difference: 3,03 mmHg) and DBP (mean difference: 1,94 mmHg). To correct for differences in gender, age, and BMI, analysis of covariance was used, including all two-way interactions. The age-exposure interaction was significant (p<0,001). For DBP, the exposed group had a slightly higher pressure, increasing with age. For SBP, from 29 years on, the exposed group had a slightly lower pressure.

Discussion
High blood pressure is an important cardiovascular risk factor, and should therefore be kept as low as possible. The DBP of workers at risk for occupational noise is slightly higher, for SBP, this is only true for workers under the age of 29.
The major drawback of the study is the absence of real exposure data. Furthermore, this is a cross-sectional study and we have no insight into the latency time between exposure and outcome. Nevertheless, due to the large dataset, these results indicate that noise should be considered as an important cardiovascular risk factor.