Utilizing criteria for assessing multiple-task manual materials handling jobs

One approach to the design or evaluation of manual materials handling (MMH) tasks is through the use of various criteria measures that have been developed. For evaluation purposes, the observed value of a criterion measure is calculated from task and workplace parameters, and compared to a specific criterion to assess the level of "acceptability" or "safety" associated with the task. This process is usually completed at the task level. Most criteria are for single MMH tasks; however, the majority of jobs involving MMH are composed of multiple tasks. One of the biggest challenges to exposure assessments of multiple tasks using criteria is the aggregation of the exposure from the individual tasks to a single metric. This paper examines issues relevant to the aggregation of criterion values from multiple MMH tasks. Assessment strategies for evaluating multiple-task MMH jobs are also discussed. The conclusions are: (1) basic and applied research is needed to enhance methodologies for analyzing multiple-component MMH tasks, (2) research is needed to assess the role of MMH criteria in the prevention of low-back disorders when MMH exposures are complex, (3) field methodologies for applying MMH criteria to complex exposures need to be operationally defined to ensure consistent use by practitioners, and (4) MMH criteria should be viewed as design and task analysis tools (i.e., compliance assessment), and not as risk assessment tools.