ASSESSMENT OF MECHANICAL EXPOSURE IN ERGONOMIC EPIDEMIOLOGY

In recent years several different methods have been developed to asses s mechanical exposures, which are related to musculoskeletal disorders in ergonomic epidemiology. Each of these methods is capable of measur ing one or more aspects of risk factors, but has drawbacks as well. Im proper application of methods might result in biased exposure estimate s, which has serious consequences for risk estimates arising fi om epi demiological studies. The aim of this paper was to systematically eval uate the usefulness of different measurement methods in terms of accur acy and applicability. Assessment of external exposure measures by sub jective judgements (from experts or self reports from workers), observ ational methods (on site or afterwards from video recordings), and dir ect measurements methods (at work or during laboratory simulations) ar e discussed far each of the dimensions of exposure level, duration, an d frequency. It is concluded that expert judgements and self reports g ive only limited insight into the occurrence of tasks and activities. Further information can be obtained from observations, which can best be combined with direct measurements of exposure to posture, movement, and exerted forces to achieve exposure profiles by occupational task. Internal exposures estimated by biomechanical modelling mostly consid er the low back and require information on postures of the different b ody segments and exerted forces, completed with movement data in the c ase of dynamic models. Moreover, electromyography (EMG) and measuremen ts of intra-abdominal pressure might be used for this purpose. Both bi omechanical models and EMG are useful methods to assess internal expos ure, but biomechanical models should not be restricted to the level of compressive forces on the lower back. Finally, current problems and f uture directions in measurement strategies and methods are discussed.