Objectives Exposure to hand-held vibrating tools may change neural and vascular function. We aimed to assess associations between cumulative exposure to hand-arm vibration and increased sensory-neural thresholds.

Methods A study group of road maintenance workers (n = 106) were classified into three exposure groups. Workers using rock drills (n = 26) and impact wrenches (n = 34), were exposed to vibration during operations at 17 ms-2 and 7 ms-2, respectively. Workers using other tools served as low-exposed controls. Sensory-neural thresholds in index and little fingers were measured using vibrametry. A sensory index was calculated and served as outcome. Exposure (ms-2) times hours (h) of exposure to each main tool were log-10 transformed and represented the unit of exposure in multiple linear regression analysis, adjusted for age, serum cotinine and carbohydrate deficient transferrin. For other tools, the number of hours operating these tools was used for exposure.

Results and Conclusions Cumulative exposure to the main tools amounted to a mean of 15 400 ms-2 h (range 100–96 000) for rock drillers and 5600 ms-2 h (range 4–12 000) for impact wrench operators. In the index finger of the dominant hand a change in sensory index of −2.7% (95% confidence interval −4.5; −0.9) per unit of exposure for rock drill exposure was found. Among impact wrench operators, the corresponding change per exposure unit was −1.6% (−3.7; +0.6). Exposure to other hand-held tools was not associated with the outcome. The findings in the other fingers were largely similar.

The findings indicate exposure-response association between cumulative exposure to hand-held vibrating tools and sensory-neural index. Exposure levels should be reduced to prevent sensory-neural changes among workers exposed to vibration at cumulative levels comparing to the exposure levels encountered in this study.