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Ergonomics is the science of fitting the demands of work to the physical capacities of the worker. Its inception during World War II by the U.S. military was in response to the realization that disparities in work demands and physical capacities can result in serious injury and death.

Ergonomic injuries have become the most common cause of workplace illness and injury in the United States. Back injuries and cumulative trauma disorders (CTDs) such as carpal tunnel syndrome, tendinitis, bursitis, and epicondylitis account for the overwhelming majority of nonfatal occupational injuries and illnesses, costing employers more than $12 billion per year in lost work time, workers' compensation payments, and medical expenses.

CTDs have increased dramatically since 1980, comprising roughly 18 percent of occupational illnesses in 1980 versus 65 percent in the late 1990s. Australia, Japan, and other countries experienced dramatic increases in ergonomics problems during the last two decades of the twentieth century. Over 332,000 cases of work-related CTDs were reported in the United States in 1994. Back injuries make up roughly 27 percent of the nonfatal occupational injuries annually, and the back is the part of the body most commonly injured during work. In November 2000, the U.S. Occupational Safety and Health Administration issued an Ergonomics Program Standard to help control ergonomics risks at work.

OCCUPATIONAL RISK FACTORS FOR ERGONOMIC DISORDERS

Occupational risk factors for ergonomic injuries include high force, high repetition, awkward postures, direct trauma or contact stress from hard or sharp surfaces, prolonged exposure to cold ambient temperatures, and exposure to whole body or segmental vibration. For cumulative trauma disorders, these risk factors may be present during hand-tool use, in manufacturing assembly or packaging jobs, or while working at computer workstations. High rates of CTDs are found in manufacturing, construction, and office trades. Back injuries are most prevalent among workers involved in manual materials handling, including truck drivers, nurses and nurses aides, forklift operators, and construction workers. High rates of back injuries are also found among workers in sedentary jobs, typically associated with postural stress.

While back injuries are administratively often handled as injuries (suggesting a single traumatic exposure) experts recognize that most back injuries and CTDs develop gradually over time from a combination of wear and tear on the nervous, vascular, and connective tissues of the body. Based upon this, corporations and experts focus their prevention strategies on reducing cumulative exposures to the risk factors described above.

STRATEGIES FOR PREVENTION

Redesigning tools or workstations to reduce the risk factors is considered to be the best approach for preventing back injuries and CTDs. Making workstations adjustable to fit the range of body sizes of workers and providing specific training in risk avoidance goals and adjustment procedures are central to prevention. For example, computer workstations that can be adjusted to optimize the height and angle of the monitor, keyboard, and chair help to reduce ergonomic risks to the extremities and back, but are effective only if employees know how to adjust them. Other steps to manage ergonomic risks include providing a system for managers and employees to work jointly toward identifying and resolving problems, employee and supervisor training on risk factors and symptoms, job hazard analysis of ergonomic risks, and proper medical surveillance and management.

RICHARD M. LYNCH

(SEE ALSO: Carpal Tunnel Syndrome, Cumulative Trauma; Ergonomics; Occupational Safety and Health; Occupational Safety and Health Administration)