| Effects of Occupational Noise Exposure on 24-Hour Ambulatory Vascular Properties in Male Workers Ta-Yuan Chang,1 Ta-Chen Su,2 Shou-Yu Lin,3 Ruei-Man Jain,4 and Chang-Chuan Chan4 1Department of Occupational Safety and Health, College of Public Health, China Medical University, Taichung, Taiwan; 2Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan; 3Institute of Environmental Health, College of Public Health, China Medical University, Taichung, Taiwan; 4Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan Abstract
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. Key words: ambulatory arterial stiffness, ambulatory vascular properties, automobile workers, occupational noise exposure, panel study. Environ Health Perspect 115:1660–1664 (2007) . doi:10.1289/ehp.10346 available via http://dx.doi.org/ [Online 23 July 2007]
Address correspondence to C.C. Chan, Room 722, No. 17, Xuzhou Rd., Taipei, 10020 Taiwan. Telephone: 886-2-3322-8082. Fax: 886-2-23222362. E-mail: ccchan@ntu.edu.tw This study was originally conducted while T.Y.C was a doctoral student at the Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University, and was completed with a faculty start-up grant (CMU93-OSH-07 513N) at the China Medical University. The authors declare they have no competing financial interests. Received 10 April 2007 ; accepted 23 July 2007.
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