A new federal study warns that high exposure to the type of radio frequency radiation (RFR) emitted by cell phones caused tumors in rodents.
The National Toxicology Program (NTP) released a final report (PDF) on radio frequency radiation on November 1, determining there is clear evidence that male rats exposed to high levels of radiation from 2G and 3G cell phones developed cancerous heart tumors.
The report is a consensus of NTP and external scientific experts, who reviewed a number of studies in March. However, NTP and FDA officials say the findings are not an immediate cause for concern, because the tumors occurred at levels humans would not likely experience. FDA officials say they actually disagree with the NTP’s conclusions.
The studies looked at the effects of RFR radiation on male and female rats, as well as male and female mice. The researchers found no concrete evidence of increased cancer risks in female rats and in mice of either gender. The NTP released its preliminary findings earlier this year.
The researchers found an increased risk of cancerous heart tumors in male rats. There was also evidence of an increased risk of tumors in male rat brains and adrenal glands. Researchers also found a temporary decrease in the body weight of pregnant rats and lower birth rates, but the body weights returned to normal after birth.
“The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone,” Dr. John Butcher, a NTP senior scientist, said in a press release. “In our studies, rats and mice received radio frequency radiation across their whole bodies. By contrast, people are mostly exposed in specific local tissues close to where they hold the phone. In addition, the exposure levels and durations in our studies were greater than what people experience.”
But, Butcher noted that the NTP believes that the link between radio frequency radiation and male rat tumors is real.
On the same day, the director of the FDA Center For Devices and Radiological Health, Dr. Jeffrey Shuren, issued a statement which sought to quell concerns that might arise from the report. The FDA is responsible for the safe public use of cell phones and any radiation-emitting devices.
“When new studies or information becomes available, the FDA conducts thorough evaluations of the data to continually inform our thinking,” Shuren said in his statement. “After reviewing the study, we disagree, however, with the conclusions of their final report regarding ‘clear evidence’ of carcinogenic activity in rodents exposed to radiofrequency energy.”
Shuren said there were abnormalities in the study’s findings and that the signs of tumors only occurred at levels 50 times higher than a human could expect to experience.
Cell Phone Safety Debated
The study is the latest in an ongoing scientific and medical debate about whether the electromagnetic fields given off by mobile devices can cause brain cancer.
While some studies have found no links between brain cancer and the use of cell phones and other mobile devices, a number of others appear to show evidence that there is a connection.
In May 2011, the World Health Organization (WHO) announced that it was classifying radiofrequency electromagnetic fields emitted by wireless phones as a possible carcinogen. Similar to this latest study, a working group of 31 scientists from around the world determined that cell phone emissions appeared to be linked to an increased risk of glioma.
However, a study released a little more than a month later by Danish researchers found no link between cell phones and brain tumors.
In May 2014, French researchers found a link between heavy cell phone use and brain cancer. Cell phone users with the longest cumulative duration of calls, 896 hours of talk time or more, were twice as likely to develop brain tumors than those who talked less.
In November 2014, Swedish researchers reported that people who use mobile phones regularly for more than 25 years have an increased risk of glioma of the brain, similar to the tumors found in the rats. That study found that cell phone radiation exposure was linked to a 30% increased risk of brain tumors overall, but at the 25 year point the risk had grown to 300%. However, even at that level, the overall chance of developing glioma was only 0.016%.
In 2013, the Federal Communications Commission (FCC) announced that it was reassessing the potential effects of radiation exposure from cell phones and mobile devices. The FCC plans to look at radiation exposure and determine how much is emitted by the devices and how those emissions affect humans.
In the meantime, experts recommend users attempt to reduce their risk by using headsets or speakerphones when possible, holding the phone away from the body, and texting instead of calling as often as possible. Some also recommend only using the phone when it has a strong signal.