Bad vibrations: Exposure-response between rock drilling and vibration sensitivity at the fingertips

Abstract

This study, conducted at the National Institute of Occupational Health in Norway, delves into the occupational health risks faced by workers exposed to vibration from handheld power tools. The research, led by Thomas Clemm as part of his PhD work at the University of Oslo addresses the limited understanding of dose-response mechanisms for neurological symptoms. The challenge of biased exposure measurements, especially in hand-guided tools like rock drills, is acknowledged, emphasizing the need for accurate exposure assessment. The research, involving 148 workers in road maintenance, evaluates dose-response relationships between HAV exposure and vibration perception thresholds (VPT) and pegboard scores. Lifetime cumulative exposure and daily vibration exposure were measured, employing health examinations, including VPT and Pegboard tests, at baseline, 2 years, and 4 years. The findings highlight a significant exposure-response relationship between rock drill exposure and VPT, with a stronger correlation using a novel exposure measure. Even workers with relatively low exposure from impact wrenches exhibit increased VPT, challenging the safety limit level. The 500 Hz test frequency emerges as a potential marker for early signs of reduced tactile sensitivity. Simultaneous measurements using tool-attached and hand-attached accelerometers reveal a significant difference, with individual working techniques influencing the variance. This underscores the importance of careful assessment and consideration of accelerometer placement to avoid exposure misclassification. The study concludes that exposure from rock drills correlates with increased VPT, suggesting a basis for risk models of HAVS. It emphasizes the need to reconsider the exposure limit level and explore the 500 Hz frequency as an early marker. The research also cautions against bias introduced by hand-attached accelerometers, underscoring the importance of precise exposure assessments in occupational health studies.