Epidemiological reviews have suggested that there is strong evidence for an association between occupational exposure to WBV and an increased risk of (low) back pain, sciatic pain, and degenerative changes in the spinal system, including lumbar intervertebral disc disorders3. In a personal meta-analysis of cross-sectional studies published between 1986 and 2014, the combined prevalence odds ratio (POR), adjusted at least for age, for 12-month LBP was 1.87 (95% CI 1.52-2.30) in 28 driver groups with exposure to WBV from agricultural, industrial or public utility vehicles when compared with unexposed control groups. In 12 driving occupations the combined POR for 12-month prevalence of sciatic pain was 1.67 (95% CI 1.25-2.23).To protect the workers against the risk from exposure to vibration at the workplace, the EU Directive on mechanical vibration4 has established daily action values and daily exposure limit values for WBV, expressed in terms of either A(8)max in ms-2 r.m.s. or VDVmax in ms-1.75. In a committee draft of ISO/CD 2631-5, a method is proposed to estimate internal spinal forces for occupational exposures to vibration containing multiple shocks5. The lumbar spine response to vibration is assessed by means of dynamic finite element models anatomically adapted to the anthropometry and posture of the exposed workers. The assessment of health risk is based on the calculation of the daily compressive dose, Sed (MPa), and the risk factor R (non-dimensional units), derived from the relation between dynamic and static internal spinal forces under consideration of individual variables such as the age of the subject at which exposure started, the daily and lifetime duration of exposures to WBV, the body mass, the body mass index and the posture of the driver.
