There is “clear evidence” that male rats exposed to high levels of radio frequency radiation used in mobile phones developed cancerous heart tumors, the U.S. National Toxicology Program said in releasing a final report summarizing a 10-year study. (Bloomberg/File)
Researchers found a link between mobile phone radiation and cancerous tumors in rats, adding to the ongoing inquiry into whether the devices pose a risk to users even as officials cautioned against extrapolating the results to humans.
There is “clear evidence” that male rats exposed to high levels of radio frequency radiation used in mobile phones developed cancerous heart tumors, the U.S. National Toxicology Program said in releasing a final report summarizing a 10-year study. Scientists found “some evidence” of the link when they released a draft report in February. The change followed a peer review.
“The change from some evidence to clear evidence reflects increased confidence that the cancer observed in male rats was associated with exposure to radio frequency radiation,” John Bucher, a senior scientist at the toxicology program, said in an email. “NTP considers either category a positive finding of cancer.”
In studies, rodents received radiation across their whole bodies, and at higher exposures and greater duration than what people experience, he said. “The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone,” Bucher said in a news release.
The Food and Drug Administration, which monitors radiation-emitting devices, said it agreed the findings shouldn’t be applied to human cellphone use.
“We disagree, however, with the conclusions of their final report regarding ‘clear evidence’ of carcinogenic activity in rodents,” Jeffrey Shuren, director of the FDA’s Center for Devices and Radiological Health, said in a news release.
The study used extremely high levels throughout the entire body and inexplicably found that exposed rats lived longer than those who didn’t experience any radiation, Shuren said. The controversial heart tumors, known as schwannomas, were only seen in male rats, and the risks of harm didn’t increase along with the dose of radiation, as experts might have expected, he said.
“The study was not designed to test the safety of cell phone use in humans, so we cannot draw conclusions about the risks of cell phone use from it,” Shuren said.
Joel Moskowitz, a professor at the University of California, Berkeley, said the study “should be taken extremely seriously.”
“These results provide conclusive evidence that cell phone radiation can cause cancer,” Moskowitz said. “We should all be concerned about our exposure to cell phone radiation. It now becomes a question of how much and what types of exposure to cell phone is safe.”
For the study, male rats were exposed to high levels of radio frequency radiation like that used in 2G and 3G cell service -- technology that hasn’t been completely replaced as the industry moves to 4G and beyond.
Scientists also studied radiation effects on female rats and mice, and found equivocal evidence as to whether cancers observed were associated with exposure.
The studies didn’t investigate radiation used for Wi-Fi or the 5G networks that phone companies are racing to develop.
The National Toxicology Program is an inter-agency program headquartered at the National Institutes of Health.
Asked about his own phone usage, Bucher said, “If I’m making a short call I have absolutely no hesitation at all in picking up the phone and using it in a traditional manner.”
But, he said, if on a long call, “I tend to just think about using ear buds or some other way of increasing the distance between the cell phone and my body.”
The U.S. Federal Communications Commission issues radiation exposure guidelines that are based on heat, and the finding that radiation harmed rats means those FCC standards are "obsolete,” said Moskowitz, the Berkeley professor.
The FDA disagreed. “The current safety limits for cell phone radiofrequency energy exposure remain acceptable for protecting the public health,” said Shuren, the Food and Drug Administration official.
Tina Pelkey, a FCC spokeswoman, said, “Scientific evidence always informs FCC rules on these issues, and we will continue to follow all recommendations from federal health and safety experts.”
CTIA, a trade group for mobile carriers including AT&T Inc. and Verizon Communications Inc., said in an email that carriers “follow the guidance of experts when it comes to cell phones and health effects.”
“We note NTP’s own assessment that today’s report cannot be extrapolated to human cell phone usage, and the Food and Drug Administration’s concurrence,” a spokesman for the trade group said.