For decades, there had been ideas loosely based on the theory that mobile phone radiation causes cancer. New studies that underwent live-broadcast peer review sessions show that mobile phone radiation could play a role in lab rats getting cancer. This study is now sparking debate as to the impact of mobile phone radiation on humans.
A pair of studies conducted by the United States National Toxicology Program determined it had “clear evidence” that exposure to radiation can cause heart tumors in male rats. The study also concluded that it found “some evidence” of brain tumors in those male rats being traced back to radiation exposure.
The studies are notable for their sizes. Researchers at the National Toxicology Program, a federal interagency group under the National Institutes of Health, tested 3,000 rats and mice of both sexes for two years—the largest investigation of RF radiation and cancer in rodents ever undertaken in the U.S. European investigators at the Ramazzini Institute in Italy were similarly ambitious; in their recent study they investigated RF effects in nearly 2,500 rats from the fetal stage until death.
When turned on, mobile phones and other wireless devices emit EF radiation continually, even if they are not being actively used, because they are always communicating with cell towers. The dose intensity tails off with increasing distance from the body, and reaches a maximum when the devices are used next to the head during phone calls or in front of the body during texting or tweeting.
Why is there concern that cell phones may cause cancer or other health problems?
There are three main reasons why people are concerned that mobile phones (also known as “mobile” or “wireless” telephones) might have the potential to cause certain types of cancer or other health problems:
- Cell phones emit radiofrequency energy (radio waves), a form of non-ionizing radiation, from their antennas. Tissues nearest to the antenna can absorb this energy.
- The number of mobile phone users has increased rapidly. As of December 2014, there were more than 327.5 million mobile phone subscribers in the United States, according to the Cellular Telecommunications and Internet Association. This is a nearly threefold increase from the 110 million users in 2000. Globally, the number of subscriptions is estimated by the International Telecommunications Union to be 5 billion.
- Over time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have increased. However, improvements in mobile phone technology have resulted in devices that have lower power outputs than earlier models.
What is radiofrequency energy and how does it affect the body?
The energy of electromagnetic radiation is determined by its frequency; ionizing radiation is high frequency, and therefore high energy, whereas non-ionizing radiation is low frequency, and therefore low energy. The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency energy. More information about ionizing radiation can be found on the Radiation page.
Exposure to ionizing radiation, such as from x-rays, is known to increase the risk of cancer. However, although many studies have examined the potential health effects of non-ionizing radiation from radar, microwave ovens, cell phones, and other sources, there is currently no consistent evidence that non-ionizing radiation increases cancer risk.
Another study investigated whether exposure to the radiofrequency energy from cell phones affects the flow of blood in the brain and found no evidence of such an effect.
The authors of these studies noted that the results are preliminary and that possible health outcomes from changes in glucose metabolism are still unknown.