Cell phones may cause brain cancer, a panel of experts reporting to the World Health Organization (WHO).
After reviewing dozens of studies that explored a possible link between cancer and the ubiquitous hand-held phones, the experts classified cell phones as "possibly carcinogenic to humans" and placed them in the same category as the pesticide DDT and gasoline engine exhaust.
The panel determined that an increased risk for glioma, a malignant form of brain cancer, appears associated with wireless phone use.
Globally, it's estimated that 5 billion cell phones are in use. "The number of users is large and growing, particularly among young adults and children," the International Agency for Research on Cancer said in a news release issued Tuesday.
The IARC made the announcement in Lyons, France, based on the work of 31 scientists from 14 countries. It will present its findings to the WHO, which may then issue its recommendations on safe cell phone use.
Experts said children are especially vulnerable.
"Children's skulls and scalps are thinner. So the radiation can penetrate deeper into the brain of children and young adults. Their cells are dividing at a faster rate, so the impact of radiation can be much larger," Dr. Keith Black, chairman of neurology at Cedars-Sinai Medical Center in Los Angeles, told CNN.
Until Tuesday's announcement, the WHO had said that cell phones were safe to use.
"The IARC working group did not conduct any new research, but rather reviewed published studies," Walls added in a news release. "Based on previous assessments of the scientific evidence, the Federal Communications Commission has concluded that '[t]heres no scientific evidence that proves that wireless phone usage can lead to cancer.' The Food and Drug Administration has also stated that '[t]he weight of scientific evidence has not linked cell phones with any health problems.'"
There has been conflicting research in recent years on the health hazards posed by cell phones. As recently as February, British researchers reported that cell phones do not increase the risk of brain cancer.
Their analysis of data on newly diagnosed cases of brain cancer in England between 1998 and 2007 -- when cell phone use was climbing -- revealed no statistically significant change in the incidence of brain cancers in men or women, said the University of Manchester researchers.
There was a very small increase (0.6 more cases per 100,000 people) in the incidence of cancers of the brain's temporal lobe. That works out to 31 extra cases per year in England's population of nearly 52 million people, the researchers said.
But the study authors also noted that cancers of the brain's parietal lobe, cerebrum and cerebellum in English men fell slightly during the study period.
That study was released online in the journal Bioelectromagnetics.
Dr. Otis Brawley, chief medical officer for the American Cancer Society, said the WHO's classification of cell phones "means that there could be some risk, but that the evidence is not strong enough to be considered causal, and needs to be investigated further. The bottom line is the evidence is enough to warrant concern, but it is not conclusive."
Dr. Nagy Elsayyad, an assistant professor in the Department of Radiation Oncology at the University of Miami Sylvester Cancer Center, agreed, saying scientists don't know much more about cell phone safety than they did before the WHO statement. "They [WHO] indicate it is a possible, not a probable source," he said. "But they still cannot come out with a positive conclusion."
Elsayyad advises using an ear piece or speaker when talking on a cell phone.
"If you hold the phone away from your brain that ought to decrease the risk tremendously," he said.