Do Wi-Fi and Bluetooth cause cancer? Mixed study results.

Electromagnetic Spectrum Illustration

“The electromagnetic (EM) spectrum is the range of all types of EM radiation,” posted NASA. “Radiation is energy that travels and spreads out as it goes — the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. Illustration and article by Patricia Bouweraerts

Wireless connections are sending data all round us like a web — a labyrinth of radio frequency (RF) waves.

At national football league (NFL) games, many stadiums in the U.S. accommodate more than 30,000 simultaneous Wi-Fi connections. Wireless and Bluetooth® applications are increasing at home with smart devices, at events — with more people connected at a venue, and in the workplace.

“Like cell phones, (wireless) routers use radio frequency (RF) energy — a form of electromagnetic radiation (EMR) — to bring wireless internet to your computer, TV, and other devices,” wrote Catherine Roberts in a March article on “Bluetooth headphones and speakers also rely on RF signals to play music. Smart watches use RF to connect to your phone. And any Wi-Fi-connected smart devices in your home also receive and transmit data using this type of energy.”

By 2020, 99 percent of employees will be using tablets at work, and 90 percent of employees will be using tablets owned by employers, according to Some companies are encouraging employees to use their own tablets for increased mobility and productivity.

“Ever since the advent of smartphones and tablets, workplaces have been adopting and evolving toward BYOD (Bring Your Own Device),” wrote Michael Lazar in a November article on “With Tech Pro Research reporting that 72 percent of workplaces will be adopting BYOD in the year to come (2018), many businesses are making preparations in advance of streamlining integration.”

Does the expanded use of mobile tablets, Bluetooth® headsets, and wireless keyboards and mice cause any health risks?

Scientists disagree whether RF exposure is totally safe, and many say that more investigation is needed. Some experts believe that multiple wireless signals may increase risk.

“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,” Roberts wrote.

What is radio frequency radiation?

Ionizing and non-ionizing radiation differ in wavelength and effects on living tissue.

Medical tests such as CT scans and X-rays, and the sun’s ultraviolet light are types of ionizing radiation. Alternatively, radio frequency (RF) is nonionizing radiation — with not enough energy to directly change cell DNA. Scientists have tested the effects of non-ionizing radiation on cells and have collected data resulting from human exposure.

“All that research — in test tubes, animals, and humans — has been mixed, with no definitive proof that cellphone radiation harms human health, but also unable to completely clear it of any potential risk,” Roberts wrote.

The American Cancer Society, Inc. (ACS) agrees.

“Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to ionize (remove charged particles such as electrons),” wrote the ACS medical and editorial content team on “RF radiation has lower energy than some other types of non-ionizing radiation, like visible light and infrared, but it has higher energy than extremely low-frequency (ELF) radiation. If RF radiation is absorbed in large enough amounts by materials containing water, such as food, fluids, and body tissues, it can produce heat. This can lead to burns and tissue damage. Although RF radiation does not cause cancer by damaging DNA in cells the way ionizing radiation does, there has been concern that some forms of non-ionizing radiation might have biological effects that could result in cancer in some circumstances.”

RF radiation focused on the eye can cause cataracts to form, wrote the ACS medical and editorial content team.

Cell phones, Wi-Fi routers, and Bluetooth devices use RF

Wi-Fi and Bluetooth are non-wired connections that use RF energy. Cell phones also communicate with radio frequency waves.

“But because the distances traveled by Wi-Fi 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,” Roberts wrote.

Several U.S. government agencies are aware of public concerns about RF exposure, and have systems for approving consumer products that use the technology.

“For example, the FDA (Food and Drug Administration) has issued guidelines for safe RF emission levels from microwave ovens, and it continues to monitor exposure issues related to the use of certain RF devices such as cellular telephones,” according to “NIOSH (National Institute for Occupational Safety and Health) conducts investigations and health hazard assessments related to occupational RF exposure.”

Since 1996, the Federal Communications Commission (FCC) has in place an approval process for all wireless communications devices sold in the U.S., to make sure products meet guidelines for safe human exposure to RF energy. These guidelines are based on Specific Absorption Rate (SAR), the rate at which RF energy is absorbed by the human body. There is a maximum permissible limit of exposure when the device is running at its highest power possible.

“For exposure to RF energy from wireless devices, the allowable FCC SAR limit is 1.6 watts per kilogram (W/kg), as averaged over one gram of tissue,” the FCC wrote.

The FCC posted that all wireless devices sold meet a set of maximum SAR standards, and these specifications include a safety margin.

Wi-Fi and Bluetooth®

A router communicates information across an office suite or building without being connected to them by wires or cables.

“Wi-Fi is designed to shuttle much larger amounts of data between computers and the Internet (than Bluetooth®), often over much greater distances,” wrote Chris Woodford on “It can involve more elaborate security and it generally uses much higher power, so arguably presents a slightly greater health risk if used for long periods.”

In contrast to cell phones and laptops typically using Wi-Fi to connect to the internet, wireless keyboards and mice transmit their signal to a computer with a type of RF, Bluetooth.

Bluetooth is a technology designed for distances of less than about 30 feet. Bluetooth devices have a built-in radio antenna to send and receive signals. Devices can also be adapted to use Bluetooth with USB sticks or with a type of laptop card. The signals transmitted are at 79 different frequencies, or channels, isolated from TV, radio and cell phones.

It’s a form of pulsed radio frequency energy, wrote Lloyd Burrell in an article updated in April on his website, Burrell is author of the book “Beating Electrical Sensitivity — The Path to Tread.”

“The frequency power of wireless headsets is the same as that of microwave ovens, which also operate at 2.4 GHz, though admittedly microwave ovens use much higher power levels,” wrote Andrew Goldsworthy, Ph.D., lecturer in biology, retired, Imperial College London. “But the power levels themselves are not the issue, it’s the rate of change of the EMF’s, the pulsing, that causes most of the biological damage. Bluetooth radiation is dangerous.”

Joel M. Moskowitz, Ph.D. is director of the Center for Family and Community Health, School of Public Health, at the University of California, Berkeley. He wrote an article in 2016 about the product released that year by Apple Inc. — AirPods. He included a section on the safety of Bluetooth technology.

“In 1975, Allan Frey published a paper in the Annals of the New York Academy of Sciences which reported that exposure to low intensity microwave radiation could open the blood-brain barrier in rats,” Moskowitz wrote. “Moreover, pulsed radio frequency waves (like Bluetooth) were more likely to produce this effect than continuous waves.”

The blood-brain barrier (BBB) is a layer of cells that let molecules helpful to brain function in, such as oxygen, glucose, amino acids, and water. The BBB also keeps harmful molecules out, such as pathogens or toxins.

“More than a dozen peer-reviewed studies have replicated Frey’s findings — exposure to low intensity microwave radiation can open the blood-brain barrier,” Moskowitz added.

Transmission strengths differ

There are varying classes of Bluetooth transmitters, Burrell wrote. Devices are measured according to transmission power in milliwatts (mW), and rated as one of the following:

  • Class 1 transmitters, most powerful, have a range of 100 meters and peak transmission power of 100 mW
  • Class 2 transmitters, typically found in mobile devices, a range of 10 meters, and peak transmission power of 2.5 mW
  • Class 3 transmitters, the weakest, range of less than 10 meters, with peak transmission power of 1 mW

Bluetooth versions are different from classes. Version designations are not about power, but refer to the speed of data transmitted. The earliest version 1.0 offered a transmission speed of 721 kbit/s, and version 3.0 + HS offers the high-speed rate of 24 Mbit/s.

Mobile phones continually modify their power used for communication based on signal strength, and working at maximum power level is intermittent, according to the FCC.

When there are more bars showing on a cell phone, the phone may use less power for sending and receiving data. When the signal from cellular towers is weaker and a phone shows only one bar, for instance, cell phones may increase power to compensate for the faint signal, Roberts wrote.

Do Bluetooth headphones expose the wearer to less RF than holding a phone close to the head?

“In theory a Bluetooth device does drastically cut down radiation exposure compared to having the cell phone next to your ear if you could be sure that you were only exposing yourself to Bluetooth radiation,” Burrell wrote. “The problem is that when you use a Bluetooth headset that the transmission strength from the cell phone itself is not decreased. If, for instance you are putting the phone in your pocket or clipping it to your belt, then you are at the same time exposing your internal organs to radiation.”

Wired headphones may not be the answer either.

“The headphone can act as a sort of antenna for your cell phone, giving the radiation a fast route into your brain,” Burrell wrote. “The science is sketchy on this but in my view, having tried wired headphones, they are not the solution to reducing your radiation exposure. …To overcome the antenna effect of wired headphones, use an air tube hands-free kit.”

An air tube system uses hollow tubing to transmit sound from the device’s speaker to the earphone.

“The tube and earpiece contain no metal conductors, hence virtually eliminating any radiation otherwise present in conventional hands-free devices,” according to the Office of Information Technology, University of California, Irvine. The voice information is transmitted by sound waves in a plastic tube, not via RF radiation. The sound quality might not be as clear as with other hands-free options, so it would be best to test one before purchasing it or get a recommendation from an acquaintance who has one.”

Information is posted by the World Health Organization, as well as the FCC in the U.S.

The FDA posts information about cell phones and RF energy. The World Health Organization (WHO) also posts a site on RF exposure resulting from mobile phone use, and on an informational site, the International Electromagnetic Fields Project (IEFP).

The International Agency for Research on Cancer (IARC) of WHO groups human carcinogens into categories and posts the classifications online. Radiofrequency electromagnetic fields are included in its “possibly carcinogenic to humans” Group 2B list.

To get a better concept of the classification hierarchy, here are a few examples in each group. Plutonium, tobacco smoking, and estrogen therapy, postmenopausal are listed in the “is carcinogenic” Group 1. To note, consumption of alcohol beverages is also part of this group. The next Group 2A, “probably carcinogenic,’ includes materials such as DDT, creosotes, and androgenic (anabolic) steroids. Group 2B, the “possibly carcinogenic” classification, lists radio frequency electromagnetic fields, in addition to substances such as chloroform, titanium dioxide, Ginkgo biloba extract, and engine exhaust from a vehicle using gasoline.

Group 3 follows as “unclassifiable as to carcinogenicity,” and Group 4 lists items that are “probably not carcinogenic to humans.”

The complete classification listing also notes viruses that have a connection to cancer, and occupational exposure to certain materials.

“Some health and safety interest groups have interpreted certain reports to suggest that wireless device use may be linked to cancer and other illnesses, posing potentially greater risks for children than adults,” posts the FCC. “While these assertions have gained increased public attention, currently no scientific evidence establishes a causal link between wireless device use and cancer or other illnesses. Those evaluating the potential risks of using wireless devices agree that more and longer-term studies should explore whether there is a better basis for RF safety standards than is currently used. The FCC closely monitors all of these study results.”

The agency writes that it is aware of several organizations promoting the reduction in exposure to RF energy.

“The FCC does not endorse the need for these practices, but provides information on some simple steps that you can take to reduce your exposure to RF energy from cell phones,” the agency wrote. “For example, wireless devices only emit RF energy when you are using them and, the closer the device is to you, the more energy you will absorb.”

Measures recommended by the FCC include increasing the distance between wireless devices and the body, and texting instead of talking — although not when driving.

“Use a speakerphone, earpiece or headset to reduce proximity to the head (and thus exposure),” the FCC posts. “While wired earpieces may conduct some energy to the head and wireless earpieces also emit a small amount of RF energy, both wired and wireless earpieces remove the greatest source of RF energy (the cell phone) from proximity to the head and thus can greatly reduce total exposure to the head.”

Also, wireless devices may interfere with cardiac pacemakers. The FCC suggests keeping the distance between wireless devices and a pacemaker greater than eight inches.

Reducing Exposure

The Consumer Reports article lists steps to consider for limiting exposure to RF, including the following:

  • Move devices away from head and other parts of the body
  • Use a wired connection when possible
  • Put the router further away from rooms where you spend the most time
  • Turn the router off at night

Does your work require a wearable unit?

“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,” Roberts wrote.

Is research moving forward?

The speed at which new wireless applications are being developed does not appear to match the rate of reliable research on long-term human health effects of these technologies.

David Einstein, a business and technology journalist, wrote an article in 2009, “Little radiation from a wireless mouse” on, the sister site of the San Francisco Chronicle.

“Wireless mice — whether they use Bluetooth or proprietary radio frequency technology, emit very little radiation,” he wrote. “When you’re sitting in your home office, you’re also getting minute doses of radiation from the computer screen and the wireless router, so what’s a little more from the wireless mouse or keyboard. By the way, there is no conclusive evidence that cell phones or Bluetooth headsets pose a health risk. On the other hand, there’s no conclusive evidence that they don’t.”

The number of people who use a mobile device for personal or work purposes is considerable.

“The vast majority of Americans – 95 percent – now own a cellphone of some kind,” according to a Pew Research Center Fact Sheet, posted in February.

That’s a lot of people, a lot of wireless headsets, phones and mice, and a thickening meshwork of radio frequencies to untangle.


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