Hung Up On Cell Phones

For years experts have been arguing about whether cell phones cause brain cancer, with most saying there’s little or no evidence of risk. The debate was supposed to be settled by the Interphone study—a big, long-term, long-awaited, long-delayed, 13-country, $25 million endeavor coordinated by the World Health Organization—the results of which finally appeared in May. That turned out to be wishful thinking, since the conclusions were, well, inconclusive—in fact, downright muddled. Naturally, scientists and advocates on both sides of the debate managed to claim vindication, while the Interphone researchers called for still more research, and the rest of us just got more static.

Busy signals and lots of howevers

Like nearly all previous research, Interphone found no overall increased risk of brain tumors in cell phone users compared to non-users. Actually, it found a slightly reduced risk among most phone users (a result the accompanying editorial called “baffling”). However, the heaviest cell phone users, who averaged about 30 minutes a day, appeared to have a higher risk of one kind of tumor (glioma), usually on the side of the head where they held the phone. But in the end, the Interphone researchers raised questions about their own findings—citing potential flaws in the study design and data collection—and disagreed about the study’s implications.

Other experts were quick to point out additional shortcomings of the study. It looked at only two common kinds of brain tumors, gliomas and meningiomas (results about two other kinds will be reported eventually). Though Interphone had the largest number of people using cell phones for 10 to 15 years of all case-control studies, cancer typically takes longer than that to develop. No children or teenagers were included, and children would be most at risk, if there is a risk. Because of the study’s delayed publication, the data are old—the cell phone use took place mostly during the 1990s. Back then, the devices emitted different levels of energy and used different radiofrequencies than today’s models. And the subjects used their phones, on average, less than people do today. Would the results be the same for current cell phone users? What about lifelong use, beginning in childhood? Finally, though there was a “firewall” designed to protect the independence of the study, critics warned that Interphone was partly funded by the phone industry, like so much previous research, and that industry-funded research has always absolved cell phones.

Worry, don’t worry . . .

Federal agencies like the FDA and CDC have long downplayed concerns about cell phones and cancer, and Interphone hasn’t changed their positions. They point out that despite the huge increase in cell phone use, the incidence of brain cancer has not increased in the past two decades. Moreover, there’s still no known biological mechanism to explain how very-low-intensity, non-ionizing radiofrequency energy, the kind of electromagnetic radiation emitted by cell phones, could cause cancer or otherwise be harmful. And researchers have found no evidence that this radiofrequency energy is carcinogenic in lab rodents or causes DNA damage in cells. (In contrast, the higher-frequency ionizing radiation from X-rays or ultraviolet light is known to damage DNA and thus promote cancer.)

Nonetheless, countries like Germany, France, Israel, Britain, and Russia have issued precautionary warnings about cell phone use, especially by children.

Just before the Interphone study was published, the annual report from the President’s Cancer Panel sent its own mixed signals about cell phones. “There is no evidence to support a link between cell phone use and cancer,” but the research on long-term, heavy use is “extremely limited” and the potential harms unclear. Until more is known, it said, people can reduce their exposure to radiofrequency energy by making fewer and shorter calls on cell phones, using landlines when possible, using a hands-free device, and sending text messages instead of phoning.

Putting it in perspective

Cell phones play a vital role in modern lives, especially in poorer countries where landline service is limited or nonexistent. They are here to stay. We have to admit, we don’t know the answer to the cancer question. But the evidence so far does not justify inordinate concern, let alone hysteria. If cell phones pose a risk, it is almost certainly very small—otherwise the research would not be so murky. Realistically, the results of future studies are likely to continue to be inconsistent and inconclusive, especially since the technology is constantly changing.

It can’t hurt to take the simple precautions from the President’s Cancer Panel, listed above, and to limit phone use by children. Whether you call this “prudent avoidance” or plain old waffling, it’s the best advice we can offer. In any case, try to avoid the numbing “everything-causes-cancer” mindset, which can distract you from taking the steps that are known to reduce the risk of cancer, like quitting smoking, testing your home for radon, and losing weight if you’re overweight.

The real way to protect yourself against cell phones: Don’t phone or text while driving. Cell phones distract drivers and cause an estimated 1.6 million crashes and thousands of deaths each year in the U.S. alone. About that, at least, the evidence is clear-cut.

UC Berkeley Wellness Letter, August 2010

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