The federal government’s National Toxicology Program released its final report Nov. 1 on whether cellphones cause cancer. The final verdict: Cellphone radiation may sometimes cause tumors in rats at high, continuous doses, but not in people.
The report leaves open the possibility that the kind of radiation produced by cellphones might have the potential to cause cancer, but it does not answer the question of how that might happen. The findings are unlikely to satisfy many people.
“The National Toxicology Program concluded there is clear evidence that male rats exposed to high levels of radio frequency radiation like that used in 2G and 3G cell phones developed cancerous heart tumors,” the National Institutes of Health, parent agency of the NTP, said in a statement.
The final report doesn’t change much that the researchers said in a preliminary report released in February. It found there is evidence that bathing rats in certain types of cellphone radiation for their entire lives might raise the risk of certain cancers in some of the rats.
The findings do not apply to people, they said.
“The exposures used in our studies are not directly comparable to the exposures that humans typically experience when using a cellphone,” the National Toxicology Program’s John Bucher told reporters.
The NTP team did not expose the rats to the 4G frequencies now in common use.
The NTP gave its February report to experts for review, and Nov. 1’s report reflects their comments. In general, Bucher said, they advised the NTP to strengthen its confidence in what was found.
The two most significant findings: Male rats bombarded with high doses of cellphone radiation had a higher risk of a type of rare cancer called a schwannoma in the nerves surrounding the heart. In February, the NTP said there was some evidence this happened but now says the evidence is clear.
And they said there was now equivocal, or unclear, evidence that some female rats may develop similar tumors.
“In the brain of males, there were increased incidences of malignant glioma,” the report added.
In a seeming contradiction, male 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 from the radiation that comes from gamma rays or nuclear energy. It can make tissue warm, but the rats were not given high enough doses to warm their tissues.