Do cellphones cause cancer? The latest studies from the federal government show that maybe, at the highest doses for the longest periods of time, cellphone radiation might cause one type of cancer in rats.
But that probably does not translate to people, experts agreed.
It’s a hotly debated topic, and the National Toxicology Program, which assesses these kinds of risks, has been studying about 3,000 mice and rats bathed in varying doses of cellphone radiation for virtually their entire lifespans — from when they are in the womb to old age.
The bottom line from the senior scientist who leads the studies: “I think the reports don’t go much further than what we reported earlier, and I have not changed the way I use a cellphone, no,” said NTP’s John Bucher.
“No, I have not recommended changes to my children,” Bucher told reporters in a telephone briefing.
The reports released Friday are an update of what the NTP reported in May of 2016. They’re being released for public comment, and then a panel of experts from outside government will discuss the findings in March.
Related: Questions about cellphone use and cancer
The two most significant findings: Male rates given high doses of cellphone radiation had a higher risk of a type of cancer called a schwannoma in the nerves surrounding the heart. In addition, rats exposed to cellphone signals lived longer than rats not exposed. They were especially less prone to a type of inflammatory kidney disease.
It’s still not clear why either thing might happen. The type of radiation that comes from cellphones is very different form the radiation that comes from gamma rays or nuclear energy. But the researchers stress that people are exposed to much lower levels of cellphone radiation than the rats were.
"The levels and duration of exposure to radiofrequency radiation were much greater than what people experience with even the highest level of cell phone use, and exposed the rodents' whole bodies. So, these findings should not be directly extrapolated to human cell phone usage," Bucher said.
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None of the studies clearly showed any increase in cancer in mice— only in rats.
“These draft reports are bound to create a lot of concern, but in fact they won’t change what I tell people: the evidence for an association between cellphones and cancer is weak, and so far, we have not seen a higher cancer risk in people," said Dr. Otis Brawley of the American Cancer Society.
“No, I have not recommended changes to my children."
"If there is a harm, it’s minimal," he added.
"But if you’re concerned about this animal data, wear an earpiece."
If the cellphone signals do cause cancer, they are a “weak carcinogen at best,” Bucher said.
“The typical cellphone call has radiofrequency radiation emissions that are very, very, very much lower than what we studied,” Bucher said.
Related: Government study links cellphone use to cancer in rats
The Food and Drug Administration, which was not involved in the studies, found the results reassuring. Dr. Jeffrey Shuren, who heads the FDA’s Center for Devices and Radiological health, notes that there has not been an increase in brain tunmors — which was the public’s biggest fear about cellphone use.
“Even with frequent daily use by the vast majority of adults, we have not seen an increase in events like brain tumors,” Shuren said in a statement.
“Based on this current information, we believe the current safety limits for cellphones are acceptable for protecting the public health.”
"The evidence for an association between cell phones and cancer is weak."
The CTIA, which represents the cellphone industry, said it would study the results.
"NTP issued partial results of its rat study in June 2016 and since then the Federal Communications Commission, the Food and Drug Administration, the World Health Organization, the American Cancer Society and numerous other 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 radiofrequency energy emitted by cellphones," it said in a statement.
Brawley said the findings won't reassure everyone.
"It’s still going to confuse people and the folks who really want cellphones to be harmful are going to say that it’s harmful," he told NBC News.
People can use common sense and an excess of caution, Brawley advised. "If I had a 6-or 8-year-old, I don’t know if I'd give them a cellphone because their brain is still developing and their skull is thinner," he said.
"I take some comfort in the fact that we have not seen a rise in brain tumor incidence in America and around the world," Brawley added.