Cell Phone Radio Frequency Radiation



Cell phones are currently used by 95% of American adults. The U.S. Food and Drug Administration (FDA) nominated radio frequency radiation (RFR) used by cell phones for an NTP study because of widespread public use of cell phones and limited knowledge about potential health effects from long-term exposure.


NTP conducted two-year toxicology studies in rats and mice to help clarify potential health hazards, including cancer risk, from exposure to RFR like that used in 2G and 3G cell phones which operate within a range of frequencies from about 700–2700 megahertz (MHz). These were published as Technical Reports in November 2018.

What did the studies find?

The NTP studies found that high exposure to RFR (900 MHz) used by cell phones was associated with:

  • Clear evidence of tumors in the hearts of male rats. The tumors were malignant schwannomas.
  • Some evidence of tumors in the brains of male rats. The tumors were malignant gliomas.
  • Some evidence of tumors in the adrenal glands of male rats. The tumors were benign, malignant, or complex combined pheochromocytoma.

It was unclear if tumors observed in the studies were associated with exposure to RFR in female rats (900 MHz) and male and female mice (1900MHz).

The results are based on NTP’s four categories of evidence that a substance may cause cancer: clear evidence (highest), some evidence, equivocal evidence, no evidence (lowest).

As a follow-up, NTP submitted a manuscript accepted for publication in October 2019 that evaluated DNA damage in three regions of the brain, the liver, and in blood cells in rats and mice that were removed at an earlier timepoint from the ongoing 2-year toxicology study. DNA damage, if not repaired, can potentially lead to tumors. This work was also included in NTP’s published Technical Reports, but this study includes analyses of the data in the supporting information not included in the Technical Reports.

NTP scientists found that RFR exposure was associated with an increase in DNA damage. Specifically, they found RFR exposure was linked with significant increases in DNA damage in:

  • the frontal cortex of the brain in male mice,
  • the blood cells of female mice, and
  • the hippocampus of male rats.

There are many factors that influence whether damaged DNA will lead to tumors. NTP plans to conduct additional studies to learn more about how RFR might cause DNA damage. Please see the FAQs below for more information about the specific studies and NTP’s cell phone RFR program.

What are NTP’s future plans for studying cell phone RFR and 5G wireless technology?

5G is the emergent technology that will eventually overtake the existing 2G, 3G, and 4G technology. In the meantime, people will continue to be exposed to RFR in the 700–2700 MHz range. As the 5G network is implemented, some of the signals used by the 5G network will use the same lower frequencies used by the older technology previously studied by NTP, but the 5G network will also use higher frequencies—up to 60,000 MHz—thereby exposing wireless users to a much broader spectrum of frequencies. The higher frequencies, known as millimeter waves, can rapidly transmit enormous amounts of data with increased network capacity compared with current technologies. Millimeter waves do not travel as far and do not penetrate the body as deeply as do the wavelengths from the lower frequencies. Millimeter waves are likely to penetrate no deeper than the skin, whereas the lower frequencies have been shown to penetrate at least three to four inches into the human body.

NTP is currently evaluating the existing literature on the higher frequencies intended for use in the 5G network and is working to better understand the biological basis for the cancer findings reported in earlier studies on RFR with 2G and 3G technologies. Additionally, work is ongoing to develop smaller RFR exposure chambers for additional short-term studies that will take weeks and months to complete rather than years. The exposure system is also being designed to have the capability to conduct studies with various RFR frequencies and modulations to keep up with the changing technologies in the telecommunications industry.

NTP also aims to repeat studies in the smaller RFR exposure chambers and to identify biomarkers of damage from RFR exposure. The biomarkers would be measurable physical changes, such as molecular changes, that can be seen in shorter amounts of time than it takes to develop cancer and that might be predictive of the disease. If scientists can better understand biological changes in animals, they will know more about what to look for in humans. Additional studies could also identify whether the behavior of animals is affected by RFR exposure.