Frequency Weighting for Vibration-induced White Finger Compatible with Exposure-response Models

Abstract

An analysis has been performed to derive a frequency weighting for the development of vibration-induced white finger (VWF). It employs a model to compare health risks for pairs of population groups that are selected to have similar health outcomes from operating power tools or machines with markedly different acceleration spectra (rock drills, chain saws, pavement breakers and motorcycles). The model defines the Relative Risk, RR f(trial) , which is constructed from the ratio of daily exposures and includes a trial frequency weighting that is applied to the acceleration spectra. The trial frequency weighting consists of a frequency-independent primary frequency range, and subordinate frequency ranges in which the response to vibration diminishes, with cutoff frequencies that are changed to influence the magnitude of RR f(trial) . The frequency weighting so derived when RR f(trial) = 1 is similar to those obtained by other methods (W hf , W hT ). It consists of a frequency independent range from about 25 Hz to 500 Hz (-3 dB frequencies), with an amplitude cut-off rate of 12 dB/octave below 25 Hz and above 500 Hz. The range is compatible with studies of vasoconstriction in persons with VWF. The results provide further evidence that the ISO frequency weighting may be inappropriate for assessing the risk of developing VWF.

Frequency Weightings for Hand-Transmitted Vibration ^|^ndash; Results of the Ottawa Workshop

“…Workplace studies, like those reported here by Bovenzi 7) , Brammer and Pitts 8) , and Pitts et al 9) , depend on reliable and consistent diagnosis of hand-arm vibration injuries and reliable and consistent evaluation of workplace exposures. Fundamentally these both are dependent on accurate reporting by individual workers, as well as accurate measurement of power tool and machine vibration.…”

Reduction in finger blood flow induced by hand-transmitted vibration: effect of hand elevation

“…Epidemiology studies have generally found only weak agreement between the occurrence of VWF and predictions based on the ISO 5349-1:2001 model (e.g. Griffin et al 2003;Bovenzi 2010Bovenzi , 2012Brammer and Pitts 2012). Both overestimation and underestimation of the occurrence of VWF have been reported (Futatsuka et al 1984;Gemne et al 1993;Griffin 1994), leading to doubts as to whether the frequency weighting for hand-transmitted vibration is appropriate for the assessment of vibration-induced vascular effects (Griffin 2012).…”

Relation between vibrotactile perception thresholds and reductions in finger blood flow induced by vibration of the hand at frequencies in the range 8–250 Hz

“…The fixed surround around the vibrating contactor in the present study was designed to (Griffin, 2012). Epidemiological studies suggest that frequency weighting W h may not be optimum for predicting the incidence of vibration-induced white finger from occupational exposures to hand-transmitted vibration, with the weighting underestimating the severity of high frequency vibration relative to the severity to low frequency vibration (Griffin et al, 2003, Bovenzi, 2010, Brammer and Pitts, 2012). …”