What’s known about the potential risk from routers and wireless headphones
By Catherine Roberts
Last updated: March 01, 2018
Recent research has resurfaced concerns among scientists about a potential link between cell-phone radiation and cancer. But that research—a 10-year, $25 million government study in rodents—left a lot of key questions unanswered. That includes how relevant the findings are to newer wireless technologies such as Bluetooth and WiFi that have become widespread since the study was designed in the early 2000s.
Like cell phones, routers use radio frequency (RF) energy—a form of electromagnetic radiation—to bring wireless internet to your computer, TV, and other devices. Bluetooth headphones and speakers also rely on RF signals to play music. Smartwatches use RF to connect to your phone. And any WiFi-connected smart devices in your home also receive and transmit data using this type of energy. Do you need to worry about any of that?
To find out, we talked with experts about what they thought about radiation from these sorts of devices, and to see whether there are any steps that people who may be concerned can take to reduce their risk.
What’s Known—and Unknown—About Radiation From Devices
The RF signals from cell phones, as well as Bluetooth and WiFi, are considered nonionizing forms of radiation. That means unlike ionizing radiation—from, say, ultraviolet light from the sun, medical tests such as CT scans or X-rays, or nuclear explosions—they don’t carry enough energy to directly break or alter your DNA, which is one way cancer can occur.
But some research suggests that nonionizing radiation can have measurable effects on living organisms. Just how worrisome the effects are is a matter of considerable and ongoing debate.
When it comes to cell phones, scientists have looked at findings from animal research and cells in test tubes exposed to RF radiation in a lab, as well as observational studies in humans. These human studies have tried to see whether heavy users of cell phones have higher rates of brain cancers and other health problems compared with people who use cell phones less often.
All that research—in test tubes, animals, and humans—has been mixed, with no definitive proof that cell-phone radiation harms human health, but also unable to completely clear it of any potential risk.
The research into the RF signals used with WiFi is even more preliminary, focused on lab and animal studies, making it even more difficult to reach firm conclusions about their safety or risk.
But researchers can make some judgments about the potential for harm based on how WiFi and similar technologies work, as well as on how people tend to use their devices. Those factors do provide some reasons to think that WiFi and Bluetooth devices may be less of a concern, says Leeka Kheifets, Ph.D., a professor of epidemiology at the UCLA School of Public Health who has studied the potential health effects of low-level radiation.
Here’s why, according to Kheifets and other experts we spoke with.
When you make a call, text, or use data, your phone sends and receives RF signals back and forth between its antenna and nearby cell towers. The radiation from Bluetooth and WiFi devices falls into the same basic range on the electromagnetic spectrum—between FM radios and microwave ovens—as the RF waves from cell phones. But because the distances traveled by WiFi and Bluetooth signals tend to be much shorter (between your router and your laptop, for instance, or your smartphone and your wireless speaker) the RF can be transmitted at a much lower power than from a cell phone, which could reduce the effect it has on living tissue.
In addition, you don’t hold routers and many Bluetooth devices right up against your head, as you are more likely to do with cell phones. And when it comes to RF waves, “distance is your friend,” Kheifets says. That’s because the strength of the signal drops dramatically as the distance from your body increases.
And even Bluetooth headphones, which obviously are used very close to your body, may pose less risk than cell phones because of their weaker signals, Kheifets says.
In fact, Kheifets and CR’s health and safety experts say that one way to reduce potential risk from cell phones is to use Bluetooth headphones rather than holding the phone next to your ear. (An even more effective strategy is to use the device’s speaker, which allows you to hold the phone away from body entirely; see below for more tips.)
While there are reasons to think that WiFi and Bluetooth may pose less risk than cell phones, that doesn’t mean they definitely pose no risks.
One problem, says Jerry Phillips, Ph.D., a professor of biochemistry at the University of Colorado at Colorado Springs who has studied the potential biologic effects of cell-phone radiation, is that the existing research hasn’t revealed the threshold below which RF signals clearly pose no threat.
And David Carpenter, M.D., director of the Institute for Health and the Environment at the University at Albany, says that while exposure from a single router in your home may be small, the risks could be greater in places that have dozens of laptops and routers working at the same time—such as school classrooms. Phillips notes that children’s developing bodies may be more vulnerable to all forms of radiation from devices.
With that in mind, several school districts in the U.S. and other countries have tried to reduce exposure in the classroom to RF radiation from devices. The Maryland State Department of Education, for example, recommended in 2016 that school districts use wired networks instead of WiFi whenever possible, turn off routers when not being used, and keep routers as far away from students as possible. In France, WiFi is banned from nursery schools.
Steps to Consider
Although any potential harm from exposure to radiation from devices is far from certain, if you want to limit your exposure, the experts we spoke with identified some simple—though sometimes potentially inconvenient—steps.
For example, Carpenter, at the University of Albany, says that he doesn’t shy away from having WiFi in his house—but the router is located away from where his family spends the most time.
If you are concerned about the RF signals from your cell phone or WiFi or Bluetooth devices, here are some ways you can limit your exposure:
When using your phone or tablet, consider keeping it away from your head and body. That is particularly true in areas where the cellular signal from towers is weak—when your phone has only one bar, for example—because phones may increase their power then to compensate. To do that, you could try texting or video-calling when possible, using the speaker phone on your device or a wired or Bluetooth headset, carrying your phone in a bag instead of stowing it in your pocket, and not resting your tablet on your body for a long period of time. When you go to bed, consider storing your phone away from where you sleep, switch it to airplane mode, or turn it off entirely.
And when considering whether to use a smartwatch or other wearable device, some of which now connect through cellular signals, recognize that the device will be close to your body for extended periods, which in theory could increase the risks.
If you’re concerned about exposure from your wireless internet connection, you could consider using a wired connection when possible, positioning your router away from rooms where you spend the most time, and turning it off at night.