April 1999 Bulletin

Study to probe workplace injuries

Seek causes of musculoskeletal disorders

The National Research Council, responding to a mandate of Congress, will conduct a two-year study of musculoskeletal disorders in the workplace.

The study follows a two-day National Research Council workshop in August 1998 on the same subject that found a "fundamental relationship between extreme work exposures and musculoskeletal morbidity."

The report of a workshop did nothing to settle the question for the two opposing sides to the issue. One side finds a causal relationship between work and musculoskeletal disorders and the other says there is no scientific evidence to prove that work alone is the source of the disorders.

In February, the Occupational Safety and Health Administration (OSHA) published a draft of a new ergonomics standard to reduce work-related musculoskeletal disorders in manufacturing and manual handling operations and other jobs in general industy where there is a demonstrated problem of work-related musculoskeletal disorders.

Industry countered that there is no scientific proof to warrant the standard and that OSHA should wait until further study proved the relationship of work activity and musculoskeletal disorders. Unions said the standard was too long in coming, and, in fact, was too general.

OSHA previously tried to issue an ergonomics standard, but has been opposed by fierce opposition from industry and by Republicans in Congress who have three times written language into appropriations bills, preventing the agency from preparing rules on ergonomics. The most recent restriction expired last October, giving OSHA a window of opportunity.

OSHA says more than 647,000 Americans suffer from injuries or illness due to work-related musculoskeletal disorders which account for more than 34 percent of all workdays lost to injuries or illnesses. The cost to employers is estimated as high as $20 billion a year in direct workers' compensation costs.

Rep. Robert Livingston (R-La.) chairman of the House Appropriations Committee, asked the steering committee that conducted the workshop to describe "the state of scientific knowledge, characterized by the degree of certainty or lack thereof, with regard to occupational and nonoccupational activities causing such conditions."

The committee responded that "the relationships among work factors, biomechanical loads and responses are supported by mathematical models and direct measurements. The mathematical models are widely accepted and applied to design mechanical structures in aircraft and automotive design. Direct measurements have been used to a lesser extent than modeling because they are potentially injurious to human subjects, but when they have been used they generally support the biomechanical models."

It has been shown, the committee said, "that load forces encountered over time in normal work activities often approach the physiological and mechanical tissue limits. Limits may be exceeded as a result of a single high force or as a result of repeated loads over time. Some tissues have a greater ability to adapt to repeated loads if there is sufficient recovery time between successive loads, while other tissues, e.g., nerves, are less able to adapt."

Biomechanical loads are encountered in activities of work, daily living and recreation, the committee observed. The contribution to these activities to tissue response is related to their relative duration and intensity.

The workshop concluded:

Focus of study

The two-year study on work-related musculoskeletal disorders will examine:

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