Cellphones and cancer: 9 things you should know right now

The debate over whether cellphone use is hazardous to your health isn't over, and it may never be.

Kent German Former senior managing editor / features
Kent was a senior managing editor at CNET News. A veteran of CNET since 2003, he reviewed the first iPhone and worked in both the London and San Francisco offices. When not working, he's planning his next vacation, walking his dog or watching planes land at the airport (yes, really).
Kent German
9 min read
Andrew Hoyle/CNET

In the 15 years that I've covered wireless industry for CNET, the debate over whether cellphone use is hazardous to our health has long simmered in the background. It comes to a boil each time a new study analyzing a possible link is released, briefly grabbing the attention of the phone-wielding public.

When relayed quickly in our sound bite news culture, such claims alarm some people. I understand why. If there's one thing that's certain about this debate, it's that passions on both sides run deep. Some readers and experts are convinced we're on the verge of a major public health crisis, while others dismiss the debate as tinfoil-hat pseudoscience. Most of the public, however, doesn't appear to care. Ever since scientists first started asking questions, cellphone use has only skyrocketed, with 92 percent of Americans now owning mobile phones .

That trend isn't going to change anytime soon. Nor should it. Despite what this study has demonstrated, and how some headlines have interpreted it, there's still no definitive answer to whether cellphones are dangerous. And as I'll discuss in a minute, we may never get one at all. This one study is not a reason to stop using your phone, and in today's modern world it would be near impossible to do so. Still, it is OK for you to pay attention to this debate and be aware of its developments. If you're just getting caught up, here's what you need to know.

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Take no study in a vacuum

Many studies exist on this topic. Some never make it off the pages of scientific journals, while others catch the attention of the mainstream media outlets. In 2016, for instance, the US National Toxicology Program released the initial results of a multiyear study that found a potential link between phone use and cancer (the full results were published in February 2018). Male rats that were exposed to the same wireless signals our cellphones emit today were more likely to develop certain types of brain and heart tumors than the control rats. The more exposure a rat received, the study reported, the more likely is was to develop a cancer of some form. No significant changes were reported in the mice used in the study,

It's serious stuff, no doubt, but remember that this is just one study in a crowded field that has been running for decades. Previous studies also have found links between phone use and cancer, while others have found no correlation (there are far too many to list here). 

As with many other things that scientists study in our universe, there's no consensus as of yet. Studies will differ, they will dispute each other and they will ask new questions we haven't asked before. Don't rely on one study to draw conclusions in your head, that's not how science works.

We may never get an answer

Science takes time -- a lot of it. Consider how long humans smoked before the evidence that it's harmful began to influence public policy. Cellphones, however, are still a new technology. "We need more data to be certain of anything," Dr. Jana Witt, Cancer Research UK's health information officer told me in a phone interview. "It's difficult to get definitive answer or proof."

Dr. Witt told me her organization would look for a comprehensive review of all available evidence showing a link. "We'd look at epidemiological (the science of how disease spreads) studies of humans that show a correlation, even if they may not be able to show a causation directly," she said. "They'd be combined with lab studies showing that [cellphone radiation] changes genetic material and studies of animals."

In other words, don't pine for a magical day when we we can say without any doubt that cellphones cause cancer. Likewise, don't wait for science to "prove" that phone use is not harmful.

Consider every study carefully

When any study is published, it will (rightfully) be analyzed and picked apart to find weaknesses or errors with the research. That's an important step that aids in further study. I won't do that here for the 2016 study, leaving it to others to point out the red flags instead.

Those include how the rats were exposed to emissions (nine hours per day and over their entire bodies is different how humans would use a cellphone), the type of rats used and their ages, whether the study was properly reviewed, small sample sizes and the fact that the study reported a "low incidence" of cancer in the test rats.

In an emailed statement, Dr. Witt wrote that it's also unclear how the findings of a study on rats would translate to people. "There's been a lot of research into any potential cancer risk of using mobile phones and overall there's good evidence that the risk of brain tumours isn't higher in people who have used a mobile phone for up to 10 years," she wrote. "Ongoing research to check for effects over a longer time, or in children, is important."

It's also wise to consider who funds a study when evaluating its findings. For example, would you inherently trust a study from the National Cattlemen's Beef Association recommending that you eat steak once a week? No, of course not.

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About a phone's SAR

For a long time, CNET kept comprehensive cellphone radiation charts, which showed the maximum SAR (aka Specific Absorption Rate, or how much radio frequency a phone emits) for every phone we reviewed.

Since 1996 the Federal Communications Commission mandates that every phone sold in the US must have a SAR of no higher than 1.6 watts per kilogram (w/kg). Before it can go on sale, the FCC tests a phone to find its SAR in facility in Maryland. Some health advocates charge, however, that the FCC test is outdated. (Canada also has a 1.6 w/kg limit, while the European Union and Australia mandate a 2.0 w/kg limit.)

Four years ago, though, we discontinued the charts because a SAR by itself isn't a reliable measure of whether a phone is safe. A handset may have a SAR of 0.9 w/kg, but that's not necessarily safer than a phone with 1.2 w/kg. A handset's SAR can vary widely during a call as you alternate between transmission bands and as you increase your distance from a tower. And it may never reach the highest recorded SAR found in the FCC test when you're using it.

What the industry says

Not surprisingly, the wireless industry, led by the CTIA in the US, is quick to insist that phone use is safe. It cites studies that back up this position and is critical of studies that say differently. The CTIA also has pushed back vigorously against local governments that have tried to mandate health warnings to cellphone use.

In 2013, after a lawsuit from the CTIA, for instance, the San Francisco Board of Supervisors voted to kill a law that would have forced phone retailers to list a handset's SAR at the point of sale. Similar legislation has mostly stalled in other cities, including in Berkeley, California. Initially, it was able to implement a law mandating health notices after the US Court of Appeals for the 9th Circuit upheld the ordinance after a CTIA suit against it. But in June, the Supreme Court ordered the lower court to reconsider its decision. 

When sorting through the mess, think again about what happened with smoking. Even if the scientific community were to reach a consensus that wireless signals are likely to cause cancer, drafting safety legislation and changing public behavior will be a long battle the industry will be intimately involved in.


Small cell radios that will deliver 5G service, like this in Doylestown, Pennsylvania, sit atop utility poles. Their rapid proliferation in residential areas is making  some neighbors wary. 

CNET/Marguerite Reardon

What the skeptics say

Those doubting a link between phone use and cancer raise a number of great questions. For instance, if cellphones really are dangerous, then why aren't brain cancers rising dramatically? Others contend that phones emit far less radiation than could ever be considered harmful and the kind of radiation (non-ionizing) they emit can't adversely affect human cells.

What's more, radiation -- at least in low doses -- is everywhere, even before the advent of wireless technology. We'll never get away from it completely: We're addicted to Wi-Fi, and we use baby monitors, walkie-talkies and cordless phones. Not all of it is harmful.

Don't dismiss health advocates out of hand

I used to get a lot of email labeling people concerned about cellphones use as fear-mongering nuts. That's an unfair generalization to make. Instead, consider that many are intelligent, sincere and well-intentioned people. Some have lost loved ones to brain cancer and worry that cellphone is a possible cause. They're not just peddling nonsense, they're looking for answers and they want to save others from the same fate. Let's meet them halfway.

On a more personal note, I'll never forget one of the first things a good friend asked me after he was diagnosed with brain cancer in 2009 (he passed away four years later). "Do you think it could be my phone?" he asked. I replied with what I knew about the debate at the time, but realized it would be of little comfort. But he just wanted to know, "Why me?"


An FCC warning on a pole with a wireless antenna in Oakland, California, shows a "no on 5G" protest sticker. 

Kent German/CNET

5G, and why study continues

It continues because it's a good question to ask. "There a lot of studies that are still happening and we're still gathering data for," Dr. Witt told me. "The evidence will become clearer in the future."

The arrival of 5G is also sparking controversy. Some homeowners are wary of "small cell" antennas going up on utility poles outside their windows, in places where they've never been before. The wireless carriers say their antenna equipment complies with FCC standards for wireless signal emissions. But the concerned residents respond that as a new technology, 5G hasn't been adequately tested. And as a new technology, perhaps a new safety standard is in order. Even so, people living near an antenna may not be able to stop it. Under the 1996 Telecommunications Act, cities are barred from considering the safety of wireless signals when considering a carrier's application to build a cell tower.

Antennas or not, the debate shouldn't be just about brain cancer. Cellphone use is affecting our bodies in other ways. They keep us awake at night, give us sore necks, and and make us more distracted. Texting and driving is incredibly dangerous, and some studies have suggested that phones could cause memory problems in teens, give children headaches, or decrease male fertility. Maybe we'll have to wait until kids raised with cellphone are well into adulthood to know more.

What you can do

If you are concerned, here's what you can do. Most of these precautions are recommended by the National Cancer Institute, the Centers for Disease Control and Prevention and the California Department of Public Health in the US; the UK's National Health Service and the Australian Radiation Protection and Nuclear Safety Agency. And even if you think these simple steps are silly, consider that following them isn't going to harm you.

  • Text instead of placing a voice call and use a headset to keep the phone away from your head when possible.
  • If you're pregnant, avoid carrying a phone next to your stomach or in your bra.
  • Men: Don't carry the phone in a pants pocket next to your groin.
  • Limit phone use for children, who have smaller and thinner skulls.
  • Don't sleep with an active phone under the pillow. Put it on your bedside table instead. And if you need to keep your phone on for middle-of-the-night emergency calls, at least silence text and app alerts so you can get a restful night's sleep.
  • Be careful with accessories promising protection. Pong's line of phones cases promise to refocus RF energy away from your head while not reducing signal strength. Again, though, there's no guarantee that such a case makes your phone safer. Don't bother with the shiny, gold-lined radiation "shields" you can find online. They're useless.

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Originally published June 6, 2016 at 12:01 p.m. PT. 
Updated Oct. 19 at 5:00 a.m. PT: Added new details and references to 5G. 

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