Musculoskeletal symptoms among young male workers and associations with exposure to hand-arm vibration and ergonomic stressors.

Objective: The overall aim of this study was to explore the association between incident musculoskeletal symptoms in the neck and upper limbs and exposure to hand-arm vibration and ergonomic stressors.

Methods: The study has a prospective design and data at baseline and follow-up was assessed by self-administered questionnaires. The study population consisted of students that had graduated from vocational high schools in 2001-2003 in northern and western Sweden and a total of 586 men responded to both the baseline and follow-up questionnaires. The mean age was 20.7 (range 19-27) years, and the exposure information included questions regarding hand-arm vibration, postural stress, computer work, mental stress and perception of muscular tension. Musculoskeletal symptoms in the neck and upper limbs were assessed at baseline and at follow-up.

Results: Men who reported their daily vibration exposure duration (work and leisure) as more than 1 h at baseline had an increased risk of neck pain in the preceding 7 days at follow-up, when adjusting for all the other exposure variables (PR 3.29, 95% CI 1.02-14.9). Men with a calculated 8-h weighted vibration exposure level [A(8)] above 1.7 m/s(2) had an increased risk of developing neck pain in both the unadjusted and adjusted analyses compared to those with an exposure level below 0.5 m/s(2).

Conclusion: Men who reported their daily vibration exposure duration (work and leisure) to be more than 1 h at baseline had an increased risk of neck pain for the preceding 7 days at follow-up. An increased prevalence of neck pain was also observed in individuals with a calculated 8-h frequency weighted vibration exposure level above 1.7 m/s(2) (calculated from data assessed at follow-up) compared to those with an exposure level below 0.5 m/s(2). The increased risks remained when adjusting for postural and mental stress; however the results could still be confounded by other ergonomic and physical load factors not adjusted for in the analyses.