Cellphones and Cancer Risk: Should I Worry About Radiation Exposure?

Q: I’m constantly on my phone, and it’s usually near my body when I’m not. Should I worry about radiation exposure?

Spending all day glued to your smartphone probably isn’t doing you any favors. Excess phone use has been linked with a range of concerns, including sleep issues, elevated cortisol levels, joint pain and even relationship woes.

But if it’s radiation you’re worried about, experts say you don’t have to ditch your phone.

“There’s no risk of anything hazardous or dangerous with radiation from cellphones,” said Gayle Woloschak, an associate dean and professor of radiology at the Northwestern University Feinberg School of Medicine.

As with all cellphones (along with Wi-Fi networks, radio stations, remote controls and GPS), smartphones do emit radiation, said Emily Caffrey, an assistant professor of health physics at the University of Alabama at Birmingham. They use invisible energy waves to transmit voices, texts, photos and emails to nearby cell towers, which can shuttle them to virtually anywhere in the world.

But nearly three decades of scientific research has not linked such exposures to medical issues like cancer, health authorities including the Food and Drug Administration say. Here’s what we know.

Not all radiation is harmful

“Radiation” describes many types of energy, some of which do carry risks, said Dr. Howard Fine, director of the Brain Tumor Center at NewYork-Presbyterian Weill Cornell Medical Center in New York City.

Atomic bombs, or, to a far lesser degree, X-ray machines, emit energy called ionizing radiation that — in high enough or frequent enough doses — can damage DNA and cause cancer, Dr. Fine said.

This is why you usually wear a protective lead blanket during X-rays.

But smartphone energy falls into a category called non-ionizing radiation, Dr. Caffrey said, which isn’t powerful enough to cause this damage.

“A lot of people think ‘radiation is radiation,’ but it’s not all the same.” Dr. Woloschak said. “There’s no DNA damage seen from cellphone use.”

The more dangerous ionizing radiation can separate electrons from atoms, which make up our DNA. Over time, DNA damage can cause cancer.

Why is there still concern?

Most experts and health authorities like the F.D.A., Centers for Disease Control and Prevention and World Health Organization agree that there’s no evidence that smartphone radiation causes health problems. Still, several studies over the years have made headlines for suggesting their links to brain tumors. Many of these studies have since been debunked, Dr. Fine said, including those focused on fifth-generation mobile networks, or 5G.

In one study published in 2010, for instance, researchers found a small association between one type of brain tumor and the highest levels of cellphone use. But the study’s own researchers noted that “biases and error” prevented them from proving cause and effect. Of the study’s various flaws, according to its authors, one was that it relied on people with brain cancer to correctly remember exactly how much they used their phones over many years.

All of the experts interviewed for this story said that the few studies that have suggested that smartphones pose radiation risks didn’t actually prove that cellphones caused those health issues.

Most people in the United States own cellphones, according to the Pew Research Center — and it would be nearly impossible to single out cellphones as a reason someone developed cancer, Dr. Fine said. Unrelated risk factors, such as exposure to air pollution, smoking, unhealthy habits or even just chance, could have been the culprits.

Yet studies with flaws like these have muddied perceptions about phone safety, the National Cancer Institute says.

Staying on the safe side

Cellphones today are nothing like the brick phones of the early 2000s. The phones we’ll use next decade will be different, too. This makes it challenging to study the long-term risks from any one phone. But Dr. Fine said radiation has actually decreased with newer technology, and Dr. Woloschak said new networks aren’t riskier than older ones, either.

“5G radiation is no higher than the 4G was,” she said. “It just allows for greater data transfer.”

Still, the Federal Communications Commission and its international counterparts set radiation limits for new phones. This explains why, in September, French authorities told Apple that it must lower the radiation levels emitted by the iPhone 12 to comply with its maximum limits. Apple rolled out a software update to fix the issue.

Dr. Caffrey said these limits are based on radiation levels that could theoretically raise our body temperatures a fraction of a degree. According to Dr. Woloschak, radiation would need to heat our bodies several full degrees to pose health risks like burns or a fever. “A cellphone’s never going to do that,” she said.

Caroline Hopkins is a health and science journalist based in Brooklyn.