Because of the widespread cellphone use and limited knowledge about the potential health hazards associated with it, the U.S. Food and Drug Administration nominated radio frequency radiation (RFR) used by cellphones to be studied by the National Toxicology Program (NTP). And "these findings should not be applied to human cellphone usage", said Dr. Jeffrey Shuren, FDA's chief of radiological health. 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.
Although the tests were done on rodents at levels much higher than humans are now exposed to there was a clear link with male rats. Bucher added that the mice were also exposed to radiation across their whole bodies, which is not what happens in people, who instead receive only local exposure to the specific area where they hold the phone.
"A major strength of our studies is that we were able to control exactly how much radio frequency radiation the animals received, something that's not possible when studying human cell phone use, which has often relied on questionnaires", said Michael Wyde, lead toxicologist on the studies.
Currently, 95 percent of American adults use cellphones.
Unexpectedly, the study also found that, overall, the male rats exposed to the cellphone radiation lived longer than the rats who were not exposed to the radiation.
Researchers found that upon exposure to high levels of RFR, there was "clear evidence" of tumors in the hearts of male mice, "some evidence" of tumors in the brains of male mice, and "some evidence" of tumors in the adrenal glands of male mice.
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He gave no indication whether they made progress on settling an escalating tariff war over Beijing's technology policy. Chinese foreign ministry spokesman Lu Kang was upbeat about the phone call, saying it had been "extremely positive".
The rats were exposed to radiation at a frequency of 900 megahertz, typical of the second generation of cellphones that prevailed in the 1990s, when the study was first conceived.
If your parents have been stressing that you're going to get a brain tumor because of your smartphone, tell them to rest easy. For comparison, fourth generation (4G) and fifth generation (5G) phones employ much higher frequencies, which are "far less successful at penetrating the bodies of humans and rats", the New York Times reports.
For the study that was just released, the National Toxicology Program (NTP) collaborated with technical experts from the National Institute of Standards and Technology (Boulder, CO) and the Foundation for Research on Information Technologies in Society (Zurich, Switzerland). "In addition, the exposure levels and durations in our studies were greater than what people experience".
"If scientists can better understand biological changes in animals, they will know more about what to look for in humans", the NTP said in its fact sheet on the study.
"We note NTP's own assessment that today's report can not be extrapolated to human cell phone usage, and the Food and Drug Administration's concurrence", a spokesman for the trade group said.
Then, the central issue at hand: "In both studies (GSM and CDMA), exposure to RFR in male rats resulted in higher numbers of animals with tumors of the heart and brain".
Scientists have divided these rodents into several groups, each of which received a different dose of irradiation, since the maximum allowed for mobile phones and ending levels exceeding this figure by about 3-4 times.