Scientists on Thursday warned US legislators of the risks of brain cancer from cell phone use, highlighting the potential risk for children who use mobile phones. We urgently need more research," said David Carpenter, director of the Institute of Health and Environment at the University of Albany, in testimony before the House Subcommittee on Domestic Policy. "We must not repeat the situation we had with the relationship between smoking and lung cancer," Carpenter said. Ronald Herberman, director of the University of Pittsburgh Cancer Institute, said that most studies "claiming that there is no link between cell phones and brain tumors are outdated, had methodological concerns and did not include sufficient numbers of long-term cell phone users." Many studies denying a link "defined regular cell phones as 'once a week,'" added Herberman. "I cannot tell this committee that cell phones are definitely dangerous. But, I certainly cannot tell you that they are safe," he said. Carpenter and Herberman both told the committee the brain cancer risk from cell phone use is far greater for children than for adults. Herberman held up a model for lawmakers showing how radiation from a cell phone penetrates far deeper into the brain of a 5-year-old than that of an adult. "Every child is using cell phones all of the time, and there are three billion cell phone users in the world," said Herberman. He added that, like the messages that warn of health risks on cigarette packs, cell phones "need a precautionary message."