"We could tell from the 7,000 comments that we got that people have strong feelings about this," Assistant Labor Secretary Charles Jeffress said Monday. Nevertheless, he said, "We're on a schedule to have a final rule adopted by the end of this year. That remains our current goal."

Corporate lawyers turned out in force Monday, as the administration began nine weeks of public hearings, to grill officials from the Labor Department's Occupational Safety and Health Administration, which Jeffress heads. The earlier comments came in a period set aside for write-in observations.

A lobbying coalition including the U.S. Chamber of Commerce, the National Association of Manufacturers and hundreds of other business groups and corporations is demanding that the administration scrap the proposal. It is not based on sound science, the coalition says, and its costs are grossly underestimated.

"You're asking businesses to spend billions of dollars while failing to ensure the prevention of these injuries," the coalition spokesman, Al Lundeen, said.

Republicans in Congress have pushed for delays and won a 30-day extension of the public comment period. But the administration, hedging its bets against the possibility of a GOP takeover of the White House, is determined to complete the rules during President Clinton's last months in office.

Jeffress offered assurances Monday that the administration will listen to all suggestions about how to improve the rules before enacting them.

The proposed regulations, rolled out in November after years of holdups imposed by Congress for scientific research and other scrutiny, would require employers to minimize everyday physical — or ergonomic — stresses of certain jobs.

OSHA officials laid out their case in opening testimony Monday, saying each year 1.8 million workers have musculoskeletal injuries related to ergonomic working conditions, and 600,000 people miss work because of them.

Injuries to muscles, nerves, ligaments and tendons include such problems as carpal tunnel syndrome, back pain and tendinitis.

Marthe Kent, head of OSHA's regulatory programs, said the agency has devoted a decade of study to the problems and has observed that in the meantime, some companies have come up with effective solutions on their own.

"The science base is strong, the risk is significant and feasible means of reducing that risk are widely available and understood. The time to act is now," Kent said.

The new rules would cover a broad range of workers from nurses to baggage handlers at airports and people who work at computers or on assembly lines.

Labor unions, also represented at Monday's session, want even stronger protections — for example, penalties against companies that intimidate workers from reporting ergonomic injuries.

OSHA estimates businesses would spend $4.2 billion a year to comply but predicts net savings of $9 billion in medical costs and increased productivity.

Businesses claim the government is far underestimating the cost. The corporate-financed Employment Policy Foundation pegs the price of worker education, reconfiguration of workspaces and workers' compensation at $80 billion annually.

Companies also say the rules are overly broad, requiring them to address individual physical problems that may be the result of factors other than working conditions, such as a person's overall health or activities at home.

At Monday's hearing, Baruch Fellner, a lawyer for UPS and Anheuser-Busch, read aloud from a section of the regulations recommending employee characteristics that companies should consider, such as whether a worker is tall or short, has small hands or wears bifocal glasses.

"Could you give us some other examples? How about the slowest, least-coordinated employees?" asked Fellner.

Ergonomics hearings are scheduled to move to Chicago on April 11, then to Portland, Ore., on April 24 before a wrap-up back in the nation's capital May 8-12.