ABSTRACT
The proper quantification of risk factors in occupational settings is an essential part of controlling occupational injuries and illnesses. Commonly, the first step in ergonomic interventions is to assess the problem at hand by quantifying the “known” potential risk factors identified through prior epidemiological evidence and/or through ergonomic guidelines and practices. For example, there is epidemiological evidence that an increase in the weight beyond a certain level in manual materials handling (MMH) jobs may lead to an increase in the likelihood of a low backrelated disorder. An ergonomist evaluating an MMH job with historically high incidence of low back injuries would consider the weight of objects that workers handle as a primary factor for the observed high incidence of back injuries. In many instances this approach may prove successful. However, there are instances where simply reducing the weight of the object may not be sufficient substantially to reduce the injury experience of a given job, or may not be a feasible approach. This could be due to the fact that there are factors that may be interacting with the object weight. It is the simultaneous or combined effects of the object weight with other risk factors that may better explain the link between the job exposures and the injury outcome. When such an interactive relationship is ignored or poorly quantified, intervention measures that rely solely on reducing the weight may prove to be ineffective.
