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A NEW US federal study of the potential dangers of mobile phone radiation, conducted in rats, has found a slight increase in brain tumours in males.
The results have raised long-dormant concerns about the safety of spending so much time with mobile phones glued to our ears. But the study had enough strange findings that it has caused other federal scientists to highlight flaws in the research, and experts say these findings and those from other studies continue to suggest the potential risk from mobile phone radiation is very small.
The National Institutes of Health study bombarded rats with mobile phone radiation from the womb through the first two years of life for nine hours a day.
It found tumours in 2 to 3 per cent of male rats, which the study’s authors called low. But females weren’t affected at all and, strangely, the rats not exposed to the mobile phone radiation died much faster — at double the rate — of those that were.
The results were preliminary, and only part of what will ultimately be released.
They were made public before they were officially published — and despite strong criticism from other NIH scientists — because the results were similar to other studies that hint at a potential problem, said study author John Bucher.
The study is part of a seven-year, $US25 million ($A34.64 million) effort conducted by the National Toxicology Program at the request of the Food and Drug Administration.
It looked at the specific type of radiation that mobile phones transmit, called non-ionising radiofrequency.
“This is the first study to actually show that non-ionising radiation (causes) cancer,” said Dr Otis Brawley, the American Cancer Society’s chief medical officer. The cancer society praised the study for “evidence that cellphone signals could potentially impact human health” but noted it didn’t quite address real risk to people.
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“If cellphones cause cancer, they don’t cause a lot of cancer,” he said in an interview. “It’s not as carcinogenic as beef.” He said people should be far more concerned about “distraction caused by cellphone”, which he said caused more deaths.
Both Brawley and Bucher said that would not change how they used their own cellphones.
While the study found what Bucher called a likely cause of cancer in rats, he cautioned that how that applied to humans “is not currently completely worked out. This may have relevance. It may have no relevance”.
Since about 1986 US brain cancer deaths had not increased or decreased, Brawley said. That suggested that whatever effect mobile phones might have it was so small as to be undetectable amid regular cases of brain cancer.
Also Brawley and others point out that mobile phone technology has improved so much in recent years to emit less radiation than medical studies simulate. Bucher said the levels the rats were subjected to would be considered “heavy”.
The study also found a slight increase in a very rare type of heart tumours in the male rats exposed to mobile phone radiation. The same NIH scientists looked at mice, but those results won’t be ready until next year.
Some of the study’s own reviewers had trouble accepting the results because of the odd factors, such as rats in the group that wasn’t exposed didn’t contract what would be the normal number of brain tumours for that population.
“I am unable to accept the authors’ conclusions,” wrote outside reviewer Dr Michael Lauer, deputy director of NIH’s office of extra-mural research. “I suspect that this experiment is substantially underpowered and that the few positive results found reflect false positive findings.” The fact that the rats exposed to radiation survived longer than those that weren’t “leaves me even more sceptical of the authors’ claims”, Lauer wrote. Four other study reviewers — three from NIH — also raised questions about the way the study was conducted and its conclusions.
Bucher said he couldn’t explain that strange factor, nor could he explain why females were not affected. Brawley said it could be the female hormone oestrogen was offering some cancer protection as had been seen in some other cancers.
If people were truly worried, they should use Bluetooth or headsets, Brawley said.
In 2011 a working group of the International Agency for Research on Cancer said mobile phones were possibly carcinogenic. But numerous studies over the years, before and after that listing, have found little evidence of a problem.