* Corresponding author. Tel.: 1508-435-9061; fax: 1508-435-
8136; e-mail: patrick.dempsey@libertymutual.com.
International Journal of Industrial Ergonomics 24 (1999) 405}416
Utilizing criteria for assessing multiple-task manual materials
handling jobs
Patrick G. Dempsey*
Liberty Mutual Research Center for Safety and Health, 71 Frankland Road, Hopkinton, MA 01748, USA
Received 15 December 1997; received in revised form 6 July 1998; accepted 4 August 1998
Abstract
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 speci"c criterion to assess the level of `acceptabilitya
or `safetya 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) "eld methodologies for applying MMH criteria to complex exposures need to be operationally de"ned 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.
Relevance to industry
Jobs in a variety of sectors (e.g., manufacturing, service, transportation) often require workers to perform multiple
manual materials handling tasks. However, most available evaluation methods focus on the stresses associated with
individual tasks. The methods for assessing exposure to multiple-task manual handling jobs are discussed, with particular
emphasis on epidemiological investigations and compliance assessments performed by practitioners. 1999 Elsevier
Science B.V. All rights reserved.
Keywords: Manual materials handling; Exposure assessment; Compliance assessment
1. Introduction
Losses associated with manual materials hand-
ling (MMH) represent the largest source of work-
related injuries and illnesses. Overexertion of the
low-back represents the majority of MMH losses
0169-8141/99/$ - see front matter 1999 Elsevier Science B.V. All rights reserved.
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