Validation of the new whole-body vibration evaluation methods on the basis of the data of the previous epidemiological study "whole-body vibration" (wbv), Project part B

Status:

completed 08/2008

Aims:

Although it must be assumed that the forces in the spine are the principal cause of the pathogenesis of the spine disorders, whole-body vibration are evaluated with factors based on the human sensation of vibration. For the exposure data measured during the previous wbv-study force-related characteristic values were computed and the relationship between these values and the medical findings were assessed. Force-related guidance values were assessed which appropriately represent the effects of long-term exposure.

Activities/Methods:

The force-related characteristic values were computed from the K-values of the wbv-study using the Fritz force evaluation model. Estimated valuations of the force-related guidance values were based on biomechanical laws and principles. On the basis of the force-related guidance values the health risks of the different vibration exposures were assessed and compared with the medical findings and in the case of discrepancies the values were adjusted.

Results:

In spite of the influence of the median frequency good correlation were given between the force-related assessment values and the "Beurteilungs-Schwingstärke" and between the force-related assessment values and the assessment accelerations. However, the ratio between respective values was not constant. With increasing values the increase of the force-related values was stronger than that of the two assessment values conforming to the standards. This relationship is given by the force-related weighting functions. By these functions low-frequency vibration parts are weighted with higher values than by the weighting functions in VDI 2057 of the year 1987 or 2002. In order to analyse the relationship between the different vibration values and the relative health risk the odds ratios were computed for the predictors assessment acceleration and force-related assessment value. Only minimal differences existed between both types of predictors. Thus the health risk can be equally well assessed by means of the sensation-related assessment accelerations and by the force-related assessment values.

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