WASHINGTON -- They were ubiquitous and used several times a day, and early warnings of cancer risks did little to curb their prevalence.

The story of cigarettes in the middle of the 20th century could be replicated now with cell phones, lawmakers and researchers warned yesterday at a U.S. Senate subcommittee hearing.

Sen. Arlen Specter, D-Pa., was the driving force behind a hearing of the Senate Appropriations subcommittee on Labor, Health and Human Services, Education and Related Agencies.

University of Pittsburgh cancer researcher Devra Lee Davis told the panel that mounting scientific evidence shows a link between cancer and long-term cell phone use, though it is far from confirmed. It could be decades before the true risks are known because cell phones were not heavily used until the mid-1990s.

The purpose of the hearing was to help determine if the subcommittee should give the National Institutes of Health additional funding for research on the topic. But the participants were simply eager to call attention to the issue.

"There's no one in this room today who doubts that we should have acted sooner about tobacco," Dr. Davis said. "When President Nixon started the War on Cancer in 1971 -- an admirable act -- he ignored tobacco, although the surgeon general had warned about its dangers in 1964."

Dr. Davis said the science is far from conclusive, but urged more research into the cancer and cell phone link -- funded by a $1 per year tax on cell phone users -- as well as warning labels for phones.

Researchers Siegal Sadetzki, of Tel-Hashomer, Israel; Dariusz Leszczynski, of Helsinki; and Olga Naidenko, of Washington state, agreed with Dr. Davis' sentiment. Several nations have issued warnings about cell phone use causing brain tumors -- especially in children, whose brains absorb more radiation.

The researchers advocated keeping the phone at least an inch away from your body at all times and not using it when signal strength is low and the phone must use more power to reach a tower. They advocated using headsets but not Bluetooth earpieces, because those also emit radiation.

The only lawmakers to stay for the full session were subcommittee chair Sen. Tom Harkin, D-Iowa, and Mr. Specter, who asked Mr. Harkin to convene the hearing. Mr. Specter said he was first alerted to the issue by Pitt cancer researcher David Servan-Schreiber, and referenced his own bout with cancer and longtime support of NIH.

Mr. Specter pressed and interrupted the witnesses when their answers struck him as long-winded or unsatisfactory, especially John Bucher, associate director of the national toxicology program for the National Institute of Environmental Health Sciences, which is part of NIH.

Dr. Bucher described a current $24 million NIH project studying the effects of cell phone radiation on mice, which will not be completed until 2014. He hedged when asked repeatedly by Mr. Specter if NIH has any recommendations on safe use of cell phones, especially for children. Mr. Specter asked him to return with a recommendation for the subcommittee on the various studies and findings.

Linda Erdreich, senior managing scientist at Exponent in New York, gave a counterpoint to most of the panel, saying that research has been inconsistent on the topic and has not shown a definitive link. She said she couldn't prove an absence of a cancer connection, but that the other researchers have overstated their case.

"What comes through to me is we just don't know what the answer is," Mr. Specter said. "Precautions are not a bad idea. They may not be a good idea, but they're not a bad idea."

Mr. Specter recommended that cell phone companies "study the testimony here very carefully" and suggested they might be forced to study the issue as well.

CTIA-The Wireless Association, a lobbying group for wireless companies, released a statement during the hearing pointing to conclusions by the U.S. Food and Drug Administration, the World Health Organization, the American Cancer Society and NIH that cell phone use is not proven to cause health problems.

Dr. Naidenko, a senior scientist at the Environmental Working Group, a D.C.-based research and advocacy organization, said that the newest research is starting to move away from those conclusions.

Environmental Working Group released a study last week that reviewed more than 200 studies and concluded that in the past two decades, the studies have produced conflicting results -- but now that researchers are able to study people who have used cell phones for many years for the first time, health problems have been more prevalent.

In addition to the hearing, cell phones and brain cancer are the subject of a conference that concludes today just a few blocks away from the hearing room on Capitol Hill. The room was packed yesterday with people who walked over from the conference -- called "Cell Phones and Health: Is There a Brain Cancer Connection?" and hosted in part by Pitt. The crowd cheered for the panelists who made strong statements about cell phone risks and grumbled at skeptical comments.

The lawmakers stressed that they did not want to cause alarm, and no one said they were swearing off cell phones altogether, but the tobacco comparisons and rhetoric of the researchers were grim.

"What's evidence?" Dr. Davis said, challenging those who say the research is inconclusive at best.

"Do we insist that the only evidence we accept is when we have enough sick and dead children? I hope that's not the case."