In a study that is sure to intensify the debate around the already controversial ergonomics standard issued by the U.S. Department of Labor late last year, the National Academy of Sciences (NAS) reported evidence that some jobs increase risk for musculoskeletal disorders (MSDs) and that intervention programs can be effective.

Critics of the new standards have maintained that they are too broad and fail to discriminate between work-caused injuries and “lifestyle-caused” injuries.

According to NAS, scientific evidence shows that musculoskeletal disorders of the lower back and upper extremities can be directly attributed to particular jobs and working conditions — including heavy lifting, repetitive and forceful motions, and stressful work environments.

Each year, these disorders affect about 1 million workers and cost the nation between $45 billion and $54 billion in compensation expenditures, lost wages and decreased productivity. But the problem can be reduced with well-designed intervention programs, the study also asserts.

“Scientifically based prevention efforts can be effective in the workplace, substantially reducing the risk of job-related musculoskeletal disorders,” said Jeremiah A. Barondess, chair of the panel that wrote the report and president of the New York Academy of Medicine, New York City. “However, the connection between the workplace and these disorders is complex, partly because of the individual characteristics of workers — such as age, gender and lifestyle.”

Lower back pain, tendinitis, nonspecific wrist complaints and carpal tunnel syndrome are among the disorders that supporters of the regulations say have considerable social and economic impact, with back pain making up the overwhelming share of reported problems.

When the Occupational Safety and Health Administration began making plans to implement regulations covering MSDs in the workplace, Congress asked the National Academy to review scientific evidence on work-related causes of MSDs as well as prevention strategies. Academy researchers evaluated scientific literature on the topic, invited outside experts to share insights at their meetings and visited two Ford Motor Company plants.

They found a strong relationship between back disorders and jobs where workers manually lift materials, frequently bend and twist their bodies or experience whole-body vibration from motor vehicles. A rapid work pace, monotonous work, low job satisfaction, little decision-making power and high levels of job stress also are associated with back disorders, the study said.

For upper-extremity disorders, repetition, force and vibration are important risk factors, according to the report. In addition, highly demanding and stressful work environments are consistently associated with the occurrence of this type of MSD.

Among men, those who work as construction laborers, carpenters and operators of industrial truck or tractor equipment are at the highest risk for developing MSDs.

For women, the highest-risk jobs are in nursing or nursing support, and in domestic or commercial cleaning and janitorial work. But musculoskeletal disorders are a problem in many industries — from agriculture, manufacturing and mining to finance, the service sector and transportation, the report says.

Although general principles to reduce the risk of work-related MSDs can be used to develop intervention strategies, programs must be tailored to specific workplaces, the report says. These programs must be evaluated over time. More broadly, rigorous methods should be developed to compare outcomes of various intervention efforts.

Because the nation lacks a uniform and comprehensive method to gather and track data on MSDs, a coordinated and standardized data-collection system is needed, the report adds. To that end, the Bureau of Labor Statistics should provide more comprehensive surveillance of work-related MSDs by obtaining from employers specific information about jobs, workplace illnesses and the characteristics of workers performing certain jobs. Standardized coding procedures and more precise and consistent descriptions of risk factors should also be developed for large data systems, the report suggests.

The report calls on the National Institute of Occupational Safety and Health to expand the scope of its research and training activities and to take the lead in creating definitions of musculoskeletal disorders for research and other purposes — measures that would require funding increases.