A comprehensive study of exposure to the radiation emitted by mobile phones found an increased risk of a rare tumor in some rodents, although the scientist in charge cautioned against drawing conclusions about the impact on humans.
Male rats developed heart tumors when exposed to high levels of a type of radiation used by the wireless telephone industry, according to the draft studies released Friday. Female rats and mice didn’t get the same tumors, the studies showed. Results were posted online.
The 10-year, $25 million toxicological studies are the most comprehensive assessments to date of health effects and exposure to radio frequency radiation in rats and mice, according to the online notice from the National Institute of Environmental Health Sciences, a unit of the National Institutes of Health, the U.S. medical research agency. The toxicology program is headquartered at the National Institute of Environmental Health Sciences.
The findings shouldn’t be extrapolated to humans because the rats were exposed to higher levels of radiation than people take in, even with heavy mobile phone use, said John Bucher, a senior scientist with the National Toxicology Program. The rats received radiation over their entire bodies for nine hours a day for two years.
“I haven’t changed the way I use a cellphone,” Bucher said on a call with reporters.
However, in an emailed release, Bucher said the tumors observed in the studies “are similar to tumors previously reported in some studies of frequent cellphone users.” Asked if that points toward hazard for humans, he said phone providers are “moving more and more toward lower power exposures to humans” as new generations of mobile service come become available.
Some studies have found limited evidence of an increased risk of cancer from mobile phone use, according to the online notice from the National Institute of Environmental Health Sciences.
And two years on, the heart tumors were “the only positive finding that we’ve been really able to have confidence in,” Bucher told reporters. “The reports don’t go much further than what we have reported earlier.”
‘No Known Health Risk’
“International and U.S. organizations and health experts have maintained their longstanding conclusion that the scientific evidence shows no known health risk due to the RF energy emitted by cellphones,” said Justin Cole, a spokesman for the trade group.
The National Toxicology Program’s studies are to undergo peer review at a March meeting.
The study found an increased risk of cardiac schwannoma, a tumor type that typically originates from cells found in neurons. It’s so unusual in the heart that doctors often write up their findings for medical journals when the tumors are found in cardiac tissue.
An unusual pattern of cardiomyopathy, a sign of an enlarged and damaged heart, was seen in both male and female rats, the study found.
Separately, the Federal Communications Commission in 2013 asked for comments on whether U.S. standards need to be updated to protect people from mobile-phone radiation, and it hasn’t acted. The agency last reviewed standards in 1996, when fewer such phones were in use. Its guidelines set maximum radiation exposure levels based on the amount of heat emitted by mobile phones.
The reports, along with earlier research show that current limits for mobile phone radiation, “remain acceptable for protecting the public health,” Jeffrey Shuren, director of the FDA’s Center for Devices and Radiological Health, said in an emailed statement.
“We have not found sufficient evidence that there are adverse health effects in humans caused by exposures at or under the current radio frequency energy exposure limits,” Shuren said.