Exposure variables in ergonomic epidemiology.

The ergonomic field is rather new to epidemiology and ergonomists are usually without knowledge in epidemiology. This review presents exposure variables used in ergonomic epidemiology, especially those that concern mechanical trauma to the musculoskeletal system at the workplace and suggests how to approach exposure definition, exposure assessment, and exposure evaluation. The exposure variables that define the exposure can be divided into five main categories: posture, motion/repetition, material handling, work organization, and external factors. There is no consensus on how different exposure variables should be pooled and interpreted as single estimates of cumulative exposure. For future ergonomic epidemiology, it is suggested that exposure be described by different exposure variables giving an exposure profile and not by a single estimate of the exposure. The possibly short time-response relationship for many work-related musculoskeletal disorders provides a challenge in evaluating different cumulative exposure measures. These measures could easily turn into effective hazard surveillance tools. Large etiological fractions found for some musculoskeletal diseases indicate a great potential for ergonomic interventions.