WASHINGTON -- Only limited scientific evidence exists showing that employer programs to combat alcohol and drug abuse are effective, a panel of research and medical experts said in a report released Monday that questioned the billions of dollars being spent annually on such efforts.

"Workplace-oriented interventions cannot solve society's problems with alcohol and other drugs," said the report by a committee from the National Research Council and the Institute of Medicine. The findings, however, were immediately challenged by advocates of corporate involvement in efforts to fight drug and alcohol problems.

The report noted that nearly $1.2 billion is being spent annually on workplace drug-testing programs alone. The committee cited a lack of thorough research into the relationship between testing programs and worker productivity. Studies that have been done often suffer from significant flaws, the report said.

The report raised special concerns about pre-employment drug testing, noting that job applicants have none of the safeguards that employees enjoy in dealing with the serious consequences of the test results.

"If a positive test result is reported by the laboratory, the applicant should be properly informed and should have an opportunity to challenge such results," the report recommended.

That opportunity should include "access to a medical review officer or other qualified individual to assist in the interpretation of positive results, before the information is given to those who will make the hiring decision."

The committee was formed in 1991 by the Commission on Behavioral and Social Sciences and Education of the National Research Council and the Division of Health Promotion and Disease Prevention of the Institute of Medicine. The council, principal operating arm of the National Academy of Sciences and the National Academy of Engineering, provides science and technology advice under a congressional charter, as the Institute of Medicine does on health policy.

With its work funded by the National Institute on Drug Abuse, the committee's mission was to analyze scientific knowledge on the prevalence and cause of drug consumption by the U.S. work force, its impact on work performance and the effectiveness of work site prevention and treatment programs.

The study is likely to generate controversy because the Clinton administration, like the Bush and Reagan administrations, puts great emphasis on attacking alcohol and drug abuse through the workplace.

Attorney General Janet Reno and Lee P. Brown, director of the White House's office of national drug control policy, had not yet received the report Monday, their offices said. But Brown, in an interview, underscored the value he places on anti-drug programs in the workplace. He said the efforts improve worker safety
and health, reduce sick time and enhance productivity, making the nation more competitive.

Reno, in a speech last May to the Institute for a Drug Free Workplace, made clear her support. "I think corporate and business Americans have in many respects taken the lead in initiatives that I think have a long range impact on drug abuse in America," she said.

Mark A. deBernardo, executive director of the Drug Free Workplace institute, contended the report was misleading. "A lot of these conclusions taken out of context will prove useful to opponents of drug testing," he said.

He joined Thomas Hedrick, president of the New York-based Partnership for a Drug-Free America, in arguing that if workplace programs did not work, profit-minded corporations would drop them.

Hedrick said he was "not at all surprised" by the report's conclusion there is little hard evidence about the effectiveness of such programs. He said the major reason has been the confidentiality of private sector companies, which either don't want to be seen as part of the drug problem or decline to share information on their employees.

The report cited 1990 estimates that approximately 7 percent of American workers had used an illicit drug in the month before being surveyed, down substantially from the 14 percent of the general population found to have used one or more illicit drugs in 1979.