Whole-body vibration and back pain-related work absence among heavy equipment vehicle mining operators.

Abstract

To determine the association between several whole-body vibration (WBV) exposure estimates and back pain-related work absence. Exposures (based on the weighted daily root mean square acceleration, A(8); the daily vibration dose value, VDV(8); and the daily equivalent static compression dose, S_ed(8)) of 2302 workers during 4 years were estimated using each worker's monthly vehicle operation records and WBV measurements from 11 different types of heavy equipment vehicles in a large coal mine. Company payroll data provided work absence during the concurrent 4 years of exposure. Cox regression models estimated the associations between the different WBV metrics and time to first work absence related to back pain. An adjusted R² statistic provided a measure of model fit. All estimated metrics of WBV exposures were positively and significantly associated with back pain-related absence. HRs varied from 2.03 to 12.39 for every 0.21 m/s² increase in the A(8)-based exposures; from 1.03 to 1.18 for every 1.72 m/s^1.75 increase in VDV(8)-based exposures; and from 1.04 to 1.07 for every 0.06 MPa increase in S_ed(8)-based exposures. Models using the estimated VDV(8) metric for the z axis fit the data best as measured by the R² statistic. Higher WBV exposures were associated with back pain-related absences in this population, which appears after a few years of follow-up. Introducing controls to lower exposure levels may help reduce back pain-related work absences.