Objectives: To investigate prospectively the relation
between vibration-induced white finger (VWF) and
measures of cumulative (lifetime) exposure to handtransmitted
vibration (HTV).
Methods: Two hundred and forty-nine HTV workers and
138 control men of the same companies participated in a
3-year follow-up study. The diagnosis of VWF (Raynaud’s
phenomenon in the controls) was based on the medical
history, the administration of colour charts and the results
of a cold test. Tool vibration magnitudes were expressed
as root-mean-square (r.m.s.) acceleration, frequencyweighted
according to international standard ISO 5349-1
and also unweighted over the frequency range
6.3–1250 Hz. From the vibration magnitudes and
exposure durations, alternative measures of cumulative
vibration dose were calculated for each HTV worker,
according to the expression: dose = Sai
mti, where ai is
the acceleration magnitude on tool i, ti is the lifetime
exposure duration (hours) for tool i, and m = 0, 1, 2 or 4.
Results: The incidence of VWF varied from 5 to 6% in the
HTV workers versus 0 to 1.5% for Raynaud’s phenomenon
in the controls. After adjusting for potential confounders,
measures of cumulative vibration dose derived from total
operating hours and high powers of unweighted acceleration
(ie, , with m.1) gave better predictions
of the occurrence of VWF than dose measures calculated
from frequency-weighted acceleration (ie, ). These
findings were observed in the entire sample of HTV
workers, in those with no VWF at the initial investigation,
and in those with normal cold test results at baseline.
Conclusions: This prospective cohort study suggests
that measures of cumulative vibration doses constructed
from unweighted r.m.s. acceleration perform better for
the prediction of VWF than dose measures calculated
according to the recommendations of current standards.
These findings should contribute to the improvement of
the ISO frequency weighting for evaluating the severity of
hand-transmitted vibration.
