Background: Epidemiologic studies have demonstrated that occupational noise exposure is associated with hypertension, but the related mechanism in vascular structural changes is unclear.
Objective: This panel study aimed to investigate effects of occupational noise exposure on ambulatory vascular structural properties in male workers.
Methods: We recruited 20 volunteers and divided them into a high-noise-exposure group of 15 and a low-noise-exposure group of 5 based on environmental noise measurement in an automobile manufacturing company. We determined individual noise exposure and measured personal ambulatory vascular property parameters simultaneously during 24 hr. Linear mixed-effects regression models were used to estimate transient and sustained effects of noise exposure on vascular parameters by adjusting some confounders collected from self-administrated questionnaires and health checkups.
Results: The high-noise-exposed (85 +/- 8 dBA) workers had significantly higher systemic vascular resistance (SVR) than the low-noise-exposed workers (59 +/- 4 dBA) during work and sleep periods. Contrarily, low-noise-exposed workers had significantly higher brachial artery compliance (BAC), brachial artery distensibility (BAD), and systemic vascular compliance (SVC; marginal, p = 0.07) than high-noise-exposed workers during off-duty periods. We also found that high-noise-exposed workers had significantly lower BAC (1.38 +/- 0.55 %mL/mmHg) and BAD (1.29 +/- 0.51 %/mmHg), as well as lower SVC (0.24 +/- 0.10 mL/L/mmHg), but higher SVR (1.93 +/- 0.67 mL/L/min) compared with low-noise-exposed workers over a 24-hr period.
Conclusions: Our findings suggest that in automobile workers, occupational noise exposure may have sustained, not transient, effects on vascular properties and also enhances the development of hypertension.
Keywords: ambulatory arterial stiffness; ambulatory vascular properties; automobile workers; occupational noise exposure; panel study.