Do exposure limits for hand-transmitted vibration prevent carpal tunnel syndrome?

Abstract

Background An apparently high frequency of carpal tunnel syndrome (CTS) among shipyard workers undergoinghealth surveillance because of exposure to hand-transmitted vibration (HTV) prompted concernsthat current regulatory limits on exposure might not protect adequately against the disorder.Aims To explore whether within regulatory limits, higher exposures to HTV predispose to CTS.Methods As part of a retrospective audit, we compared duration and current intensity of exposure to HTV incases with new-onset CTS and controls matched for age. Conditional logistic regression was used toquantify associations, which were summarized by odds ratios (ORs) and 95% confidence intervals(CIs).Results There were 23 cases and 55 controls. After adjustment for body mass index and previous diagnosisof diabetes, no clear associations were observed either with duration of exposure to HTV or withcurrent intensity of exposure. Risk was non-significantly elevated in men with ≥30 years' exposure toHTV (OR 1.6), but in the highest category of current exposure [8-h energy-equivalent frequencyweightedacceleration (A8) ≥ 4.0 m/s2], risk was lower than that in the reference category (A8 < 2.5m/s2). Moreover, there was a significantly reduced risk of CTS in men with a previous diagnosis ofhand-arm vibration syndrome (HAVS) (OR 0.2, 95% CI 0.1-0.9).Conclusions We found no evidence that below the current limit for A(8) of 5 m/s2, higher exposures to HTVpredispose to CTS. However, care should be taken not to overlook the possibility of treatable CTSwhen workers with diagnosed HAVS present with new or worsening sensory symptoms in the hand.