A recent National Cancer Institute study that found "little evidence" that formaldehyde exposure causes cancer in workers was sharply criticized at a congressional hearing yesterday on grounds that industry was too involved in the research and that the conclusions were more optimistic than the data warranted.

Scientists from the institute said a more detailed analysis of the figures after the study's release has revealed a heightened risk of nose and throat cancer, increasing with the amount of exposure to formaldehyde.

"I think this is the beginning, not closure, on the issue of formaldehyde," NCI director Dr. Vincent T. De Vita Jr. said of the study.

Formaldehyde, a proven carcinogen in animals, is a major industrial chemical; 9 billion pounds are produced annually in the manufacture of plastics, plywood, textiles and other products. About 1.3 million U.S. workers in more than 50,000 factories are exposed to it.

The four-year, $1 million study, released in March, was heralded by manufacturers as proof that formaldehyde was safe, both in the workplace and in consumer products. The study also has been used as ammunition by industry in a debate over a proposed change in the level of exposure allowed by the Occupational Safety and Health Administration.

But at yesterday's hearing of the House Energy and Commerce subcommittee on oversight and investigations, critics objected to both the methodology of the research and the conclusions that were drawn.

Dr. Philip J. Landrigan, director of environmental and occupational medicine at New York's Mount Sinai School of Medicine, charged that NCI departed from scientific norms by agreeing with participating companies to keep secret the specific sites chosen for study and the criteria for selecting them.

Rep. Ron Wyden (D-Ore.) accused NCI's Aaron Blair, the study's director, of violating the "fairness test" by briefing a group representing formaldehyde manufacturers on the study results last September, but refusing to provide the results to officials of OSHA, the Environmental Protection Agency or labor unions until the study was released five months later.

Wyden and subcommittee chairman John D. Dingell (D-Mich.) also challenged Blair for failing to heed criticisms by members of the study's six-member scientific advisory panel, five of whom signed a letter to Blair in April charging that he had interpreted the study's findings too optimistically.

The letter, written by panel chairman Dr. John M. Peters, expressed particular concern that the report had played down "the finding of a significant increase in the risk for lung cancer" for workers first exposed to formaldehyde 20 years or more before their deaths.

Blair said he had modified his conclusions to reflect the panel's concerns. "The central charge in that letter is that the study does not exonerate formaldehyde," Blair told the subcommittee. "I have never claimed that the study exonerates formaldehyde."

Blair acknowledged reporting the study's results in September to a health research committee of the Formaldehyde Institute, a group representing formaldehyde manufacturers, but said he did so because scientists from Du Pont and Monsanto were coauthors of the study. Under questioning, he said that the meeting also included representatives of companies not involved in the research.

Dingell also questioned Blair and De Vita about a provision in the study protocol that said technical changes in its design had to be agreed to by industry representatives. De Vita maintained that NCI made all key scientific decisions, but Dingell persisted, "It literally gives them a veto, doesn't it?"

Blair replied, "You might interpret it that way."

John F. Murray, president of the Formaldehyde Institute, argued that NCI's cooperation with industry had worked well. "We did not know, and frankly I can say we were apprehensive as to what the study would show," he said. "We still wanted sound answers."

In designing the study, NCI scientists did not respond to labor union concerns that plants chosen might not yield a group of workers with formaldehyde exposure representative of the industry, according to Margaret Seminario, associate director of occupational safety, health and social security of the AFL-CIO.

"That's exactly what happened," she said. Seminario said few workers studied had exposures above 1 part per million (ppm), even though current OSHA standards allow exposures of 3 ppm. She said OSHA has proposed limiting exposure to 1 ppm, and final briefs on the regulation are due next month.