WASHINGTON, April 9 (UPI) -- Radiofrequency waves from cell phones, base stations and wireless networks do not cause harm to people, a new work group report says, but the book on the much-debated issue is not yet closed.
"From what we know now, it doesn't seem like there's a lurking hazard," said study lead author Peter Valberg, principal and senior health scientist at the Gradient Corporation, an environmental consulting firm in Cambridge, Mass.
Valberg and colleagues at the World Health Organization in Geneva reviewed current data from research on radiofrequency waves and health, including information from a WHO expert workshop, observational studies of people who use cell phones and experiments with animals exposed to radiofrequency waves.
They also focused on data from base stations and wireless networks, which allow the world's 1.4 billion cell phone users -- about 20 percent of the global population -- to stay connected. Not surprisingly, the number of such stations has skyrocketed in recent years, prompting some environmental organizations and individuals to question if the station antennas, which also emit high amounts of radiofrequency waves, could be dangerous.
Others cite evidence, though inconsistent, of a relationship between radiofrequency exposure and brain tumors -- due to the cell phone's proximity to the head -- as a reason for alarm.
Much of the fear surrounding cell phones and cancer can be traced to 2000, when Maryland neurologist Dr. Chris Newman claimed on CNN's "Larry King Live" that his longtime use of a cell phone had caused his brain cancer.
By and large, however, the evidence has not convinced most scientists of any adverse health effects. For instance, although cell phones are a relatively new technology, people have been exposed to comparable radiofrequency waves from radio and television for decades, and no parallel explosion in health problems have resulted, the authors wrote in the study, which appeared in the March issue of Environmental Health Perspectives.
Everyone on Earth is exposed to myriad sources of radiofrequency waves. These waves are measured in how many times the waves circulate per second. For instance, FM radio has about 100 million cycles per second, and microwave ovens circulate about 2,000 million cycles per second. A typical cell phone falls in between at 800 million cycles per second.
Microwaves, radios and cell phones, among other technologies, are considered "non-ionizing radiation" -- they are below the boundary of ultraviolet light, and thus cannot physically break apart a chemical bond and damage a human cell.
But ionizing radiation, such as X-rays, are above the ultraviolet light boundary. These exposures can mutate cells and lead to cancer. Scientists have studied ionizing radiation for more than 100 years, and the mechanism of cell damage is well-understood.
The only way radiofrequency waves could hurt people, scientists say, is through tissue heating, which occurs when intense, excessive exposure to waves literally burns molecules in the body, kind of like sunburn. Government regulations ensure these extreme levels of exposure do not reach the public.
And there is simply no known biological process for how non-ionizing radiation from cell phones can damage a cell, says John Moulder, a professor of radiation oncology at the Medical College of Wisconsin in Milwaukee.
"People have looked hard to find one, but haven't been able to," Moulder said. "It's at the point where it almost verges on the impossible."
If cell phone radiofrequency waves did distort a cell's makeup, Moulder added, "we'd have to rewrite the physics books."
Despite Valberg and colleagues' conclusions, the public will likely -- and justifiably -- remain suspicious, Valberg said, just as they are about any new technology.
To be sure, there are studies, though not successfully replicated, that suggest a risk from radiofrequency waves. A few animal studies -- 30 to 40 out of hundreds -- have shown rats develop cancer when exposed to radiofrequency waves, Moulder said. But if a researcher repeats an experiment over and over, the rules of statistics say some of the outcomes will be detrimental -- a nuance many in the public don't realize, he said.
"It's these hints (that) people might have a tendency to fasten on to and say, 'Well, the jury is still out,'" Valberg said.
And, of course, science is by definition ever-changing, and scientists will rarely, if ever, prove the absolute safety of anything.
For example, it is possible radiofrequency waves could harm the body through an uninvestigated pathway.
"As scientists, we waffle," said John Boice, scientific director of the International Epidemiology Institute in Rockville, Md. "You can never prove a negative ... but there is just no evidence for human health effects of concern at this moment."
Because cell phones are a new technology and affect billions of people, most experts agree research should go on. However, with the U.S. federal budget for research squeezed, it's doubtful any dollars will go to the field in the foreseeable future, Moulder said.
Yet Europeans have shown a fascination for the topic. The INTERPHONE study, a project of WHO's International Agency for Research on Cancer, has trials going on in 13 European countries to see if radiofrequency exposure to cell phones is associated with head and neck cancer. The population-based study follows cell phone users 30 to 59 who live in the study regions, and reliably traces their cell phone records. The results so far have not revealed any strong connection between cancer and cell phones.
Yet public health organizations, including WHO, have set minimal guidelines for public exposure to radiofrequency waves, requiring base stations to limit their radiofrequency emissions. Though not based on established health effects, the guidelines are a precautionary measure.
Ultimately, all of the committees investigating cell phones and health are "coming up with the same conclusions, and that should be reassuring," Boice said.
