(Reuters) - High exposure to radiofrequency radiation of the type emitted by cell phones has been linked to tumors in tissues surrounding nerves in the hearts of male rats, but not female rats or any mice, according to a draft of U.S. government studies released on Friday.
However, the levels and duration of exposure to the radiation in the studies were much greater than what people experience with even the highest level of cell phone use, and exposed the rodents’ whole bodies, the draft report from the U.S. National Toxicology Program (NTP) noted.
”These findings should not be directly extrapolated to human cell phone usage,” John Bucher, NTP senior scientist, said in a statement.
“We note, however, that the tumors we saw in these studies are similar to tumors previously reported in some studies of frequent cell phone users,” Bucher added.
Cell phones typically emit lower levels of radiation than maximum levels allowed, the draft report said.
NTP said it will hold an external expert review of its complete findings from these rodent studies on March 26-28.
U.S. health officials said there is not enough evidence to say cell phone usage poses health risks.
“Even with frequent daily use by the vast majority of adults, we have not seen an increase in events like brain tumors,” said Jeffrey Shuren, head of the U.S. Food and Drug Administration’s radiological health division.
“We believe the current safety limits for cell phones are acceptable for protecting the public health,” Shuren said.
Nevertheless, the findings are potentially a concern for device makers, especially the world’s three biggest smartphone sellers, Apple Inc, Korea’s Samsung Electronics Co Ltd and China’s Huawei Technologies [HWT.UL].
The CTIA, the trade association representing AT&T Inc, Verizon Communications Inc, Apple Inc, Sprint Corp, DISH Network Corp, and others, said on Friday that previous studies have shown cellphone RF energy emissions have no known heath risks.
”We understand that the NTP draft reports for its mice and rat studies will be put out for comment and peer review so that their significance can be assessed,” the group said.
Samsung and Apple did not immediately respond to requests for comment.
Reporting by Bill Berkrot and Caroline Humer in New York, David Shepardson in Washington and Stephen Nellis in San Francisco; Editing by Susan Thomas