Ergonomic tools for evaluating manual material handling jobs.
Waters-TR; Putz-Anderson-V; Baron-S
Advances in Occupational Ergonomics and Safety 1997: Proceedings of the Annual International Occupational Ergonomics and Safety Conference, June 1-4, 1997, Washington DC, U.S.A. Das B, Karwowski W, eds., Amsterdam, Netherlands: IOS Press, 1997 Jun; :83-86
Ergonomic methods for evaluating the physical demands of manual materials handling (MMH) jobs were discussed. The existing risk assessment tools were designed to provide quantitative estimates of the biomechanical and physiological demands associated with a specific MMH job. The more frequently used assessment tools included: the revised NIOSH Lifting Equation (NLE), the University of Michigan 3/Dimensional Static Strength Prediction Program, the Oxylog portable oxygen consumption meter, the Polar portable heart rate monitor, the University of Michigan Energy Expenditure Prediction Program, the Chattanooga Corporation Lumbar Motion Monitor, the Ohio State University Risk Assessment Model, and the Snook and Ciriello psychophysical approach for assessing manual lifting requirements. These approaches, for the most part, were based on or used biomechanical, physiological, and psychophysical data published in the literature. The results of a case study of workloads of six employees working as 'order selectors' at two dry goods grocery warehouses were presented. The subjects' jobs involved repetitively lifting cases or bags of grocery items from supply pallets to an electrically driven pallet that moved along the aisles of the warehouses. Workloads were assessed from the number of cases handled, the weight of the cases, and the handling time. Physiological effects of the workloads were assessed from actual and estimated measures of energy expenditures and heart rates during the tasks. The lifting index determined from the NLE computed for the six workers ranged from 2.7 to 9.1, indicating that there was a risk of low back injury to the workers that was 2.7 to 9.1 times greater an acceptable level. Energy expenditures varied from 2.6 to 7.3 kilocalories per minute and working heart rates from 106 to 142 beats per minute. The authors conclude that the job of 'order selector' is a high risk job for low back disorders. These results are supported by medical data which indicate that between 1987 and 1992, 17 to 40% of the 'order selectors' had an OSHA recordable back injury each year at the two warehouses.
Manual-materials-handling; Risk-analysis; Musculoskeletal-system-disorders; Manual-lifting; Warehousing; Grocery-stores; Physical-stress; Biomechanics; Back-injuries; Ergonomics; Case-studies
Advances in Occupational Ergonomics and Safety 1997: Proceedings of the Annual International Occupational Ergonomics and Safety Conference, June 1-4, 1997, Washington DC, U.S.A.