WHO: Cellphones possibly carcinogenic

A branch of the World Health Organization announced Tuesday that cellphones are "possible carcinogens" — a statement that was met with skepticism from many American cancer experts.

The statement came from the International Agency for Research on Cancer, which convened 31 international experts in Lyon, France, this past week to sort through data on cellphone safety.

Experts didn't conduct any new research, but instead analyzed exisiting studies, including two new ones that have not yet been published.

Jonathan Samet, of the University of Southern California, chairman of the IARC working group, said in the statement that "there could be some risk, and therefore we need to keep a close watch for a link between cellphones and cancer risk."

In its statement, the IARC noted a possible connection between cellphones and two type of brain tumors — gliomas and acoustic neuromas. The group says there's not enough evidence to link cellphones to other cancers.

Even the IARC acknowledges that the evidence for classifying cellphones as possible causes of brain tumors is "limited."

It also lists coffee, styrofoam cups, gasoline exhaust and common medications, such as Valium, as possible carcinogens, says Otis Brawley, chief medical officer at the American Cancer Society.

"When we as consumers hear 'possibly carcinogenic,' we freak," Brawley says. "But the data is not at all certain, and needs further study. There are probably far more people killed in car accidents caused by cellphones than from brain tumors caused by cellphones."

Some people have worried about cellphones because they emit radio waves, a form of non-ionizing, low-frequency radiation. Unlike the radiation given off by the sun, tanning beds or CT machines, however, the kind of radiation given off by phones is too weak to damage DNA, however, Brawley says.

Most human studies have shown no link between cellphones and brain tumors, says cancer epidemiologist Roberta McKean-Cowdin. A few studies have found that cellphone users are more likely to develop gliomas or acoustic neuromas, but only after frequent or long-term use, she says.

Yet Donald Berry of M.D. Anderson Cancer Center in Houston notes that there's been no increase in brain cancer rates in the USA, in spite of astronomical growth in mobile technology. If anything, Berry says, brain cancer rates may be declining slightly.

The notion that cellphones cause brain cancer is "just an urban myth that keeps coming up," Berry says. "The panel somehow decided that there is maybe something here, that's possibly carcinogenic, which ranks with everything else in the world."

Brawley notes that most studies about cellphones have important limitations. Researchers typically ask people with brain cancers about their past cellphone use, then compare their answers with those given by people who've never had cancer. But Brawley says that people may not remember their cellphone use correctly — especially if they've gone through something as traumatic as being diagnosed with a brain tumor.

Georgetown University Medical Center's Peter Shields says, "'possible' does not mean the same thing as 'it will cause cancer.'"

Shields, a professor of medicine and oncology and deputy director of Georgetown's Lombardi Comprehensive Cancer Center, notes that there are three categories of risk: possible, probable and known. Cellphone radiation falls under "possible."

"This is nothing like asbestos or smoking, which causes cancer in 1of 10 people who smoke cigarettes," Shields says.

Occupational exposures to radar and microwaves, and environmental exposures associated with transmission of signals for radio, television and wireless telecommunication were also evaluated but not found to cause risk at this time because there wasn't enough data available, says Robert Baan, a senior scientist in IARC's Monographs Program, which evaluates carcinogenic hazards of all kinds and convenes working groups three times per year.

Wireless association CTIA downplayed the risks.

"The IARC classification does not mean cellphones cause cancer," said spokesman John Walls. "Under IARC rules, limited evidence from statistical studies can be found even though bias and other data flaws may be the basis for the results."

Mobile phone use is on a steady uptick worldwide. There were 427.8 million units solds in the first quarter of 2011, a 19% increase from the 359.6 million sold a year earlier, according to Gartner.

Michael Weaver, a professor of neurosurgery at Temple University Hospital in Philadelphia, recommends people use landlines when possible — he was using one during the interview — or use headsets with cords that keep the phone at a distance, and opt to text instead of call.

Weaver says there could be more brain tumors and memory problems in the heaviest mobile device users as time goes on.

"But it will take a decade or two to bear this out. You're not going to see the effects of the heavier users for a decade or so," he says.

Baan says newer cellphones, third- and fourth-generation models, emit less radiation than those from the late 1990s and early 2000s, when the research IARC evaluted was conducted. But, he says, millions more phones are now in use.

According to the IARC, more than 5 billion cellphones are used globally.

The IARC will publish its findings on the carcinogenic hazard from radiofrequency electromagnetic fields in The Lancet Oncology's July 1 issue and online in several days.

Contributing: Scott Martin