Do cellphones cause cancer?
Cell phones are more widespread than ever, and the debate about whether they can cause brain cancer continues unabated. With the results of each new study, scientists and advocates on both sides of the debate manage to claim vindication. Will the static ever stop?
Busy signals and lots of feedback
The overall incidence of brain tumors in many countries has risen since the 1950s (starting long before cell phones). A better ability to diagnose them does not fully account for this increase, raising question about environmental and lifestyle influences.
Cell phones emit very-low-intensity, non-ionizing radiofrequency energy that in the past was thought to pose little or no risk. (In contrast, the higher-frequency ionizing radiation from X-rays is known to damage DNA and promote cancer.) The amount of radiation exposure depends on factors such as the phone’s distance from the head, time spent speaking on the phone, the distance from the nearest cell phone tower, and the design and technology of the phone.
The debate about the potential role of cell phones 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 appeared in 2010. That turned out to be wishful thinking, since the conclusions were, well, inconclusive—in fact, downright muddled.
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. 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, which looked at two common kinds of brain tumors, glioma and meningioma (results about acoustic neuroma were reported the following year). Though some participants used their phones for 10 to 15 years, 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 their still developing nervous system.
Also, because of the study’s delayed publication, the data were 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 people used their phones, on average, less than they do today. Would the results be the same today, when most people use their devices more as handheld computers than as telephones? What about lifelong use, beginning in childhood? Finally, critics warned that Interphone, like so much previous research, was partly funded by the phone industry and that industry-funded research has always absolved cell phones.
Some dueling research findings
In 2011, a study of 358,000 Danish cell phone owners, published in the journal BMJ, found that even the longest users (more than 13 years) had no increased risk of brain tumors. This was reassuring, especially in light of the fact that most studies have not found a link and that brain tumor rates in Scandinavia had not risen along with cell phone usage, according to the accompanying editorial.
In contrast, a 2011 Swedish study in the International Journal of Oncology found an increased risk of malignant brain tumors among people who used cell phones for 10 years or longer, with the greatest risk in those who started using the phones before age 20. This was followed in 2013 by another study by these Swedish researchers in the same journal, which found an even stronger association between long-term cell phone use and brain tumors, including a three-fold increased risk of glioma with 25 or more years of use.
But then, also in 2013, an analysis from the Million Women Study in the U.K., published in the International Journal of Epidemiology, found no increased risk overall for various brain tumors among cell phone users. That same year, a French study in Occupational and Environmental Medicine also showed no overall association between cell phone use and brain tumors. However, subgroup analyses found that people who used cell phones the most did have higher rates of these tumors.
What about lab animals?
Until recently, researchers have found little evidence that the kind of electromagnetic radiation emitted by cell phones could cause cancer in lab rodents.
But in 2016, partial results of a well-designed multi-million-dollar study by the U.S. government’s National Toxicology Program found an increased risk of two types of brain tumors (including malignant glioma) in male, but not female, rats exposed to radiofrequency radiation similar to that produced by cell phones. The animals were exposed for the entire two years of their lives, beginning as embryos, for nine hours a day. The results have been controversial, because it’s not known if what occurs in lab animals can be extrapolated to humans, especially with such high exposure. Still, the American Academy of Pediatrics has taken the results seriously and repeated its recommendation that children should limit their use of cell phones.
Worry, don’t worry…
Federal agencies like the FDA, CDC, and Federal Communications Commission (FCC) have long downplayed concerns about cell phones and cancer. They point out that despite the huge increase in cell phone use, the incidence of brain cancer has increased little in the past two decades. Moreover, there’s still no scientific consensus about whether there are biological mechanisms to explain how the kind of very-low-intensity electromagnetic radiation emitted by cell phones could cause cancer or otherwise be harmful.
In 2011, however, the World Health Organization’s International Agency for Research on Cancer, for the first time, classified the energy emitted from cell phones as a “possible” human carcinogen.
And in 2014, the CDC published guidelines, years in the making, that recommended caution when using cell phones, especially with regard to children. But then, after weeks of closed-door debates, the recommendations were deleted.
Germany, France, Israel, Britain, Russia, and about a dozen other countries have issued precautionary warnings about cell phone use, especially for children.
Action at Berkeley
In 2015, Joel Moskowitz, Ph.D., director of the Center for Family and Community Health at the UC Berkeley School of Public Health, helped organize the International Electromagnetic Field Scientist Appeal, which has petitioned the United Nations and World Health Organization, calling for stronger regulations and health warnings on wireless technology.
Then in 2016, the city of Berkeley passed a “right-to-know” law requiring retailers selling cell phones to notify consumers about the potential radiation risk and about ways to reduce the risk. The cellular industry is challenging the law in federal court, as it successfully did with an earlier law in San Francisco.
Putting cell phone risks 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. If cell phones pose a risk, it is probably small—otherwise the research would not be so murky. Realistically, the results of future studies are likely to continue to be inconsistent, especially since cell phone technology is constantly changing. Clearly, research should continue, especially looking at heavy cell phone use in younger people.
Still, we would advise taking simple precautions—what’s known as the “precautionary principle”—particularly for children and pregnant women. Minimize holding a cell phone up against your ear; instead use a wired headset or put the call on speakerphone (there are also concerns about having Bluetooth wireless technology near your head). Text rather than call. Especially limit phone use when it shows few bars, indicating a weak signal, which means that more emissions are produced by the device.