FRIDAY, June 10, 2011 (HealthDay News) -- The debate over whether or not cell phones might cause brain tumors continues, as a new international study finds a small risk among people who are heavy cell phone users or who have used them for a long time.
Dr. Otis Brawley, chief medical officer of the American Cancer Society, was not involved with the latest research, but said that "the study is not conclusive that cell phones cause brain tumors."
The study shows a correlation between cell phone use and the risk of brain tumors, Brawley said. "But this is a suggestion, it is by no means definitive," he said.
Brawley noted there is an ongoing study bombarding the brains of mice with radio frequency radiation to see if brain tumors develop. "If that study is positive, that's going to really tell us that cell phones are not good. If that study is negative, the debate will continue," he said.
The latest report was published in the June 10 online edition of Occupational and Environmental Medicine.
Recently, the World Health Organization (WHO) added cell phones to its list of things that might cause cancer. WHO said cell phones are "possibly carcinogenic to humans" and placed them in the same category as the pesticide DDT and gasoline engine exhaust.
For the new study, a research team led by Elisabeth Cardis, from the Centre for Research in Environmental Epidemiology at the Hospital del Mar Research Institute in Barcelona, Spain, collected data on 1,229 people with brain tumors and 3,673 people without brain tumors.
People in the study were asked about how much they used their cell phones, and what phones they used.
These data are part of the Interphone Study, which is an international study of the risk of cancerous brain tumors with cell phone use that was largely funded by the Mobile Manufacturers' Forum and the Global System for Mobile Communications, two industry groups.
The researchers found that a higher risk of developing a glioma among those who used their cell phones for 10 years or more. They also had a much smaller risk of developing a meningioma, or benign tumor.
Even with these potential increased risks, the incidence of brain tumors is fairly rare. "Brain tumor incidence rates have been flat to slightly declining over the last 20 years," Brawley said. "That's not consistent with brain tumors being caused by cell phones."
"We know that cell phones kill people through accidents at a far higher rate than they would ever kill people due to brain tumors," he added.
"There were suggestions of an increased risk of glioma in long-term mobile phone users with high radio frequency exposure and of similar, but apparently much smaller, increases in meningioma risk. The uncertainty of these results requires that they be replicated before a causal interpretation can be made," the study authors concluded.
John Walls, vice president for public affairs for CTIA-The Wireless Association, said that "the peer-reviewed scientific evidence has overwhelmingly indicated that wireless devices, within the limits established by the FCC [Federal Communications Commission], do not pose a public health risk or cause any adverse health effects."
In a companion study in the same issue of the journal, the same group of researchers looked at the effect of levels of radio frequency on the risk of developing brain tumors. They concluded that "while amount and duration of use are important determinants of radio frequency dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain."
"It is important to take these into account in analysis of risk of brain tumors from radio frequency exposure from mobile phones," they added.
Dr. Ezriel R. Kornel, a brain and spine surgeon at Northern Westchester Hospital Center in Mount Kisco, N.Y., said even though the risk is small "there is enough concern that I think cell phone usage should be limited if you are not using an ear piece or speaker phone."
Dr. Nagy Elsayyad, an assistant professor in the department of radiation oncology at the University of Miami Sylvester Cancer Center and Miller School of Medicine, agreed that, despite the lack of conclusive evidence, it is better to err on the side of caution. "If people are heavy users, text rather than phone, use a land line rather than a cell phone," he said.
For more on brain tumors, visit the U.S. National Library of Medicine.