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Cell phones are hot. Some 85 million U.S. residents—30 percent of the population—have joined the mobile-phone revolution. Still, Americans have been relatively slow to go wireless.
Even a decade ago, when U.S. cell-phone use was a rarity, 10 percent of Swedes had taken the wireless plunge, says Maria Feychting of the Karolinska Institute in Stockholm. Today, Nordic countries remain Western leaders, with 40 percent of Danes, half of Norwegians and Swedes, and almost 60 percent of Finns using cell phones.
Many of these people are also reporting side effects, observes Monica Sandström of the Swedish National Institute for Working Life in Umeå. Last week at a Bioelectromagnetics Society symposium in Washington, D.C., she unveiled data from her agency's new survey of cell-phone users—5,000 in Norway and another 12,000 in Sweden.
One-quarter of the Norwegian users, she noted, feel warmth on or behind the ear when they use their phones. More troubling, she said, 20 percent also linked frequent headaches and recurring fatigue to cell-phone use. Her agency saw the same trends in Sweden, though the overall rates were somewhat lower, Sandström notes. At least one of the symptoms noted, which include dizziness, concentration difficulties, memory loss, and a burning sensation, showed up in 47 percent of people who reported using these wireless devices an hour or more daily.
Cellular phones, which send and receive radiofrequency (RF) signals via their attached antennas, come in digital and analog varieties. The newer, digital phones broadcast their communications in discrete bursts of energy, whereas analog devices employ continuous signals. Being energy hogs, analog phones also beam eight times as much energy into the user's head as digital phones do.
Overall, "people using analog phones reported more symptoms and more sensations of all kinds," Sandström says. However, she's quick to add, "we didn't measure RF emissions." Any headaches or other complaints might therefore trace to factors such as occupational stress, ergonomic issues, and even the warmth given off by a phone's battery.
Yet cell phones' RF emissions clearly can affect the brain, says Alan W. Preece of the University of Bristol in England. Last April, he published a study in which devices simulated a phone's RF emissions, in either digital or analog form, while volunteers sat at a computer. The researchers could switch the RF energy on or off without a user knowing.
"I was looking for memory effects but didn't find any," Preece notes. Instead, to his surprise, RF emissions from both digital and analog signals correlated with a cut in the time it took users to answer simple questions. The improvement was small, just 15 milliseconds.
Since then, he notes, a Finnish group recorded a similar drop in reaction time among people during RF exposures. And a few weeks ago, a statistical expert "acting on behalf of the Department of Health here [in Britain] reanalyzed my data," Preece told Science News. "He came up with the same results."
While hardly a hazard, the quickened reaction times demonstrate that cell-phone emissions are biologically active, Preece says. He's now probing what's going on, scouting for changes in blood flow within the brain. He's especially interested in the angular gyrus, a structure important to decision making.
Other scientists last week reported biological effects in animals triggered by bombardment with energy at power levels and frequencies typical of cell phones.
W. Ross Adey of the University of California, Riverside, for instance, showed that a pregnant rat's exposure to phone-like radiation at any of three power levels alters the activity of an enzyme—ornithine decarboxylase—in the fetuses' brains. This enzyme helps create polyamines, which are chemical markers of stress. Surprisingly, Adey noted, the lowest input of RF energy, 0.16 watts per kilogram of tissue, triggered the biggest changes in polyamine concentration.
He speculates that increased enzyme activity, which can foster certain cancers, "may offer an explanation" of tumors that he and his colleagues have observed in rats exposed to RF energy for long periods.
While concern over possible cancer risks has dominated public debate of cell-phone safety, until now there have been too few long-term users of the technology to make epidemiological studies practical, notes Feychting. She adds that by pooling data from many countries, however, detecting risks for several types of cancers should now be possible. This summer, a 13-country study of brain and other head-and-neck cancers in cell-phone users will begin under the aegis of the International Agency for Research on Cancer in Lyon, France.
Allen H. Frey, a Washington, D.C.–area consultant who has conducted cell-phone studies, hopes neurological effects won't be ignored in a rush to study cancer. Headaches, nausea, and reports of warming "could be merely the most obvious symptoms that something else is going on," he says. "There are some real indications of a hazard here."