Manual materials handling: the cause of over-exertion injury and illness in industry.

It is reported from various sources that overexertion due to lifting, pushing, pulling, and carrying objects accounts for about 27 percent of all compensable industrial injury and illness in the United States. Resulting strain/sprain injuries account for over 50 percent of workmen's compensation clams in many industries. Almont two-thirds of these involve back pain, with reported compensation and medical payments totaling well over one billion dollars annually in the U.S. An estimated 300,000 plus workers will be affected each year, 5 to 10 percent of whom will have a permanent disability and often will be unemployable. This paper attempts to describe four basic approaches used to study this occupational health problem. In so doing, a concerted effort is made to identifiy the gaps in knowledge which need to be more fully researched. The approaches utilized to understand and control the hazards of manual materials handling are: 1) epidemiological studies of job and worker attributes to identify those that individually and in combination cause musculoskeletal incidents, 2) psychophysical studies to ascertain the volitional tolerance of workers to the stress mitigated by manual materials-handling activities, 3) biomechanical studies of the musculoskeletal system during common exertions required in manual materials-handling activities, and 4) physiological studies of the strain imposed on the cardiovascular system during repeated load-handling activities. The state of knowledge from each of these approaches is summarized briefly, and a case is made that much research is still needed to substantiate the necessary controls to lessen the economic burden and human suffering associated with manual materials-handling acts in industry.