Since the Occupational Safety and Health Administration took the first steps in February toward issuing a federal ergonomics rule, the battle between proponents and opponents of such a rule has centered on fighting science with science.

The disagreement over whose science knows best came to a head on Wednesday when the House Education and the Workforce Committee approved legislation to block OSHA from proposing an ergonomics rule until completion of a study now being conducted by the National Academy of Sciences -- a two-year delay.

It was the fifth time Republicans have acted to stop the agency from addressing ergonomics, the science of fitting the job physically to the worker, for example by altering chairs, adjusting the speed of an assembly line or using special braces to ease back strain from lifting heavy loads.

Some businesses have acted on their own to guard workers against disabilities such as tendinitis, carpal tunnel syndrome, and joint and muscle injuries, but the Clinton administration wants to require employers with ergonomic problems to come up with programs to fix them.

The committee's legislation, strongly supported by business groups, was introduced by Rep. Roy Blunt (R-Mo.) shortly after OSHA issued its ergonomics proposal. The committee approved the bill 23 to 18, with only one member crossing the party line.

OSHA envisions a standard that would cover jobs in general industry such as in bakeries, supermarkets and offices. Firms whose workers suffer injuries would have to establish reporting systems and offer medical care and time off to the injured.

The rule has been eight years in the making and may still take years to become final. But the business community isn't taking any chances.

Defeating an ergonomic initiative is a priority for the U.S. Chamber of Commerce, the lead player in the National Coalition on Ergonomics, which has as its members many other powerful business groups.

They insist, as do many conservative Republicans, that there is no consensus in the medical community over what causes ergonomic injuries or the best way to address them.

Randy Johnson, the chamber's vice president of labor, said the legislation to block an ergonomics rule was "highly reasonable" because OSHA "should postpone any important rulemaking until they have enough science to know what they are doing."

Democrats and labor groups insist that the problem has been studied to death, and a majority in the scientific and medical community agree there is a link between certain jobs and workplace injuries. Nurses, for example, are at risk for back injury from handling and transferring patients, according to the American Nurses Association.

Supporters of a rule point out that the National Institute of Occupational Safety and Health and the National Academy of Sciences, in earlier studies and reports, cited "strong evidence" of a link between musculoskeletal disorders and physical factors at work.

Rep. George Miller (D-Calif.), a member of the committee, charged Republicans with being insensitive to the needs of workers. "Maybe the Republicans would understand this if we related one of the injuries to tennis," he jabbed.

Republican Vernon Ehlers of Michigan said he's very sensitive to ergonomic issues because of problems he has with his own back. But Ehlers said "these are very complex issues" and a rule "has to be done right or it doesn't work."

The day before the committee vote, Democrats mustered their best scientific arguments in an event sponsored by Rep. Nancy Pelosi (D-Calif.), who assembled a battalion of doctors, scientists and occupational experts who vouched for the adequacy of the science supporting a rule.

Pelosi sponsored a successful amendment in 1996 that allowed OSHA to work on the rulemaking. Democrats said her intervention may be needed again if the Blunt bill goes to the floor. There also is a companion bill in the Senate.

Some Democrats on the panel suggested that waiting for another study was not an attempt to clear up scientific uncertainty but an effort to put off any action in hopes that a new administration might be opposed to an ergonomics rule.

"It's an inexcusable delay tactic," said Rep. Lynn C. Woolsey (D-Calif.).

Charles Jeffress, OSHA administrator, said he doubts the new National Academy of Sciences study will turn up much new: "We know enough to act now."

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Employees in the Office of Motor Carriers in the Federal Highway Administration couldn't believe their e-mail when one of their colleagues, Curnis King, a manager in the hazardous materials program, was called a "continual pain in the ass" by Mary Pat Woodman, an OMC higher-up. Woodman was referring to a two-page memo that King wrote criticizing the organization and management of the OMC, which has been under fire for poor enforcement of its trucking safety rules. After King got Woodman's zinger, he sent a copy of it to Federal Highway Administrator Kenneth Wykle and everyone else at the OMC. Woodman wrote King a note, apologizing for sending the e-mail and saying, "I probably should be sent into cyberspace for doing such an insensitive thing." The highway administration said the incident has been reviewed and "the OMC has assured [us] that a similar mistake will not occur in the future." It also said it expects employees to conduct themselves in an ethical, courteous and respectful manner.