A look at the science so far

The evidence clearly is mounting: Your cellphone, abetted by your other digital devices, may slowly be ravaging your health.

The latest evidence is a preliminary report, published in May, of findings from a study by the National Toxicology Program, an initiative of the US Department of Health and Human Services.

The two-year study is the largest done with animals on the health effects of cellphones on flesh. Rats were exposed to full-body doses of radio-frequency radiation – the same frequencies that cellphones emit – for nine hours a day, from before birth until they were 2 years old. One in 12 of the male rats developed gliomas, a particularly virulent form of brain cancer that affects cells protecting neurons. Other rats showed ominous changes in their glial cells. Some animals grew schwannomas, which are rare cancers in and around the heart.

The study is one of more than two dozen over more than a dozen years. They all indicate possible links between cellphone use and cancers in, on and near your head, as well as other ills ranging from weakened memory to birth defects.

In 2014 alone, three major studies highlighted those links. In one, biologists at the University of Bordeaux matched cellphone use with a greater likelihood of developing gliomas. In another, scientists at China’s Third Military Medical University confirmed that exposure to cellphone frequencies hobbled the proper development of brain cells. In a third, a team at India’s National Chemical Laboratory saw the degeneration of brain cells over long-time exposure to cellphone frequencies.

More than a dozen studies have linked cellphones to a variety of cancers in the brain, skin and thyroid. Heavy use of cellphones also has been tied to damaged auditory cells, hormone disruption, weakened immunity, and even implicated in breast cancer in women who keep cellphones in a jacket pocket or tucked under a bra strap. In some studies, men who carry their cellphones in their front pants pockets show a higher rate of testicular cancer. In another, pregnant women regularly exposed to radio-frequency radiation showed a rate of miscarriage more than three times greater than women who weren’t.


For some, the National Toxicology Program study is conclusive. Consumer Reports called it “groundbreaking” (although a slew of past studies has pointed to similar conclusions) and declared that the results “show a link between cellphone radiation and cancer in rats.”

“Where people were saying there’s no risk, I think this ends that kind of statement,” says Ron Melnick, who ran the early phase of the study.

Except it hasn’t. Others, particularly in the popular press, still have doubts. The Washington Post urged readers to not “believe the hype” about cellphones’ cancer risks. Brushing off the NTP report, a New York Times reporter noted that US rates of brain cancer have remained “rock steady” since 1992 and declared that “you can use a cellphone without worrying.”

Or maybe not. While US brain cancer rates have remained steady for more than two decades, that statistic is deceptive.

University of Southern California researchers checked the figures in three large cancer registries from 1992 to 2006. In a 2012 report, they noted the US brain cancer rate had actually dropped – except for a kind called glioblastoma multiforme. The gliomas were mainly in the cerebellum and the frontal and temporal lobes. (The temporal lobes are the portion of the brain closest to the ear.) The increased rates for these tumors were found to be “significant.”

These findings reflect those of a Netherlands study that found that, from 1998 through 2010, overall cancer rates in that country increased 0.7 percent while the pace of gliomas more than doubled. Danish oncologists reported a similar trend in 2012.

The Interphone Study Group, an international investigation, looked at 5,000 people who had developed brain tumors. In 2010, the group reported that cellphone users who developed brain tumors were more likely to develop the tumors on the side of the head where they held their cellphones.

Still, the links between cellphone use and disease aren’t clear. Physicists have long noted that radio-frequency radiation is non-ionizing, meaning that it doesn’t have enough energy to warp DNA. (DNA damage is a root cause of cancer.) Scientists who note a link between increased gliomas and the global rise in cellphone use aren’t able to explain exactly how phones could give rise to brain tumors. Also, no one has been able to rule out other causes of the cancers.

Researchers have found that parts of the brain nearest the ear where the phone is held get warmer. It’s the same mechanism that microwaves use to cook meat. However, no one has proposed a compelling theory about how low levels of extra heat would cause tumors. A 2011 study at the US National Institutes of Health found some evidence that cellphone radiation could alter brain cells without heating them. A similar 2015 study in Germany suggested the same connection. But scientists haven’t been able to forge a clear connection between that effect and disease.  

The well-regarded Interphone study also offered little hard evidence. There was only a “suggestion” that the 10 percent of people who used their cellphones the most were more likely to develop tumors. But some individuals’ reports of cellphone time were found unreliable and there was no way to screen out other factors that might have caused the tumors.

As a result, the International Association for Research on Cancer still classifies cellphone radiation as a “possible” carcinogen and urges that more research be done.

Still, some are ready to turn the page. “It’s interesting to note that early studies on the link between lung cancer and smoking had similar resistance, since theoretical arguments at the time suggested that there could not be a link,” says Dr. Otis Brawley, chief medical officer of the American Cancer Society.

The controversy’s resolution may lie with investigations such as the COSMOS study by British scientists. The research includes more than 300,000 cellphone users in six European and Scandinavian countries. Participants offer health data and cellphone-use records over many years. They also report environmental factors in their lives, such as traffic noise and air pollution. COSMOS has promised to report periodically on any early signs of links between cellphone use and illness.


Your brain and heart aren’t the only organs at risk from digital devices. Your vision is potentially endangered, too.

The typical American spends up to nine hours a day looking at screens on televisions, computers, tablets or cellphones (the same number of hours that rats in the NTP study were exposed to radio-frequency radiation). Those screens emit ultraviolet, or UV, light, particularly the high-energy color blue, to help us see the screens in bright light. But just as
too much UV light from the sun can burn the skin, too much UV light from electronic screens harms the eyes.

Skin and eyes contain melanin, the body’s natural sunscreen that protects against damage from UV light. However, as we age, we produce less of it; by age 65, most of us make only half as much as we did as children. That allows UV light to overwhelm our body’s defenses and damage the eye’s interior. It’s particularly hard on the macula, a spot on the retina that’s crucial for sharp vision. The result: macular degeneration, a condition in which the center of the field of vision is blacked out and only peripheral vision remains.

Blue light also now has been classified as a “carcinogenic pollutant” linked to higher cancer rates in mice with high exposure to strong concentrations of blue light.

Prolonged exposure to digital screens is also thought by some to be the cause of increases in cataracts and cloudy eye lenses that ophthalmologists see in younger and younger people. Cataracts form when the eye’s lens becomes drier, more brittle and starts to break down. Loose bits of tissue clump together in the lens and form dark spots that block vision. The evidence of digital screens as a cause is still sketchy. But research at Israel’s Ben-Gurion University and the Charotar University of Science and Technology in India indicates a connection. It may be that the extra heat that screens deliver to the eye when held close is at fault; the eye has fewer blood vessels than other parts of the body to wick away the unnatural warmth.

The good news: You don’t have to swear off your cellphone or tablet. Eye care professionals can fit you with glasses that have melanin in their lenses to put a fresh layer between you and your screens. Several companies make “computer glasses” and optically coated panels that hang over the screen. These add-ons can screen out some, or even most, UV light. Some claim to block all of it from reaching your eyes.

There’s also the everyday problem of eyestrain. In a 2016 report, the nonprofit Vision Council surveyed 10,000 Americans and found that 53 percent reported eye discomfort from using computers and cellphones.

The American Optometric Association has even awarded the problem its own moniker: computer vision syndrome. The symptoms include headaches, blurred vision and aching neck and shoulders. Children as young as 5 exhibit the symptoms — a special concern, in part, because some evidence indicates that long, daily exposure to screens hastens nearsightedness.

It’s a slippery slope. Normally, we blink an average of once every four seconds. But that number falls by half or more when we stare at screens. When the eye isn’t protected by its natural film of tears, the eyeball can begin to dry out. That can lead to dry-eye disease, a condition in which the surface of the eyeball becomes damaged from dryness. The result: pain and permanently distorted vision.


The eyes also are the gateway for another device-related malady: sleep deprivation. The constant blue glow that screens give off mimics a component of sunlight and suppresses the production of melatonin, a hormone vital to sleep. When we use our devices at night, that signals the brain that it’s time to turn off the melatonin and wake up. People who wake in the night to check their bedside cellphone often find subsequent sleep less restful.

A 2014 study by Australia’s Woolcock Institute of Medical Research surveyed 11,500 teens and found that those who snuggle up in bed with cellphones or computers most nights were more than twice as likely to have trouble sleeping than those who don’t. Sleep deprivation among teens is associated with depression, anxiety, obesity and risky behavior.

But the problem affects all ages.

Researchers at Boston’s Brigham and Women’s Hospital conducted a study in which 12 people read on an iPad for four hours before bed for five nights in a row. Another group read printed books in low light. After a week, the groups switched. In both cases, those reading on iPads were shown to have shorter restorative REM sleep cycles, had disrupted body clocks and felt sleepier in the mornings, even after eight hours of sleep.

The inadequate supply of melatonin doesn’t just keep you awake. It’s also been tied to increased chances for prostate, breast and ovarian cancer, as well as clinical depression. When you don’t sleep well, you raise your risk of maladies ranging from inflammation and depression to weight gain and cancer — not to mention poor productivity throughout the day.

Here, too, color filters can help. Also, a company called f.lux has created software linked to your device’s clock. As bedtime nears, the software will adjust the screen’s light to tune down blue light and shift more to amber hues compatible with normal sleep patterns.


As the data supporting the health risks of cellphone use mount, the need to counter those with new technologies or products that reduce risks forms the foundation for a “clean phones” industry.

The world is wireless; it will stay that way. While mass movements to give up cellphone use won’t materialize, growing segments of the population will seek alternatives that minimize risks.

Industry experts and digital technology companies already provide some simple ways to minimize risks associated with digital devices. For example, a company called RF Safe makes earbuds to block radiation to your head. Many experts advise cellphone users to hold the phone at least a foot in front of their face like a microphone instead of against your head. Air tube headsets are promoted as a healthier way to use cellphones. Insulated cases for the devices are also promoted to provide more protection between cellphones and the user’s body.

But these are baby steps. The research is accelerating toward the consensus that cellphone use poses a variety of health risks. As the science builds, so will the urgency for the public to seek products that minimize those risks, especially for children. 

Addictions are addictive! People still smoke despite all the research. And digital addiction to our devices is far greater in reach. From toddlers to aging boomers and seniors, the digital addiction is pervasive throughout society — a trend that has never been seen before.   – TJ  

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