More than 250 million Americans now subscribe to a cellular phone service. That is greater than 82 percent of the population. Because these wireless devices emit radio frequency waves, some scientists have suggested that the phones increase our risk for brain tumors. Thus far, however, most studies have failed to establish a convincing link between cell phone use and brain tumors. A new Scandinavian study provides more reassurance. Researchers examined the incidence of brain tumors in four countries between 1974 and 2003 and found no evidence of an increase as mobile phones became widely popular. Studies have shown a similar lack of connection in the U.S. But experts agree that it may be decades before we can know the truth - brain cancers are slow growing and thus an increase may not be detectable yet. Out of an abundance of caution, some neurologists even suggest limiting cell phone use now, especially for children whose brains are still developing and who will likely be using this new technology for decades to come.