There is now 'clear evidence' that cell phone radiation can cause cancers of the heart, brain and adrenal glands, a landmark National Institutes of Health (NIH) study warns.
A final report, released today, confirms the preliminary findings that were released in 2016 after scientists were alarmed by early indications that cell radiation may be carcinogenic.
Although the tests were done on rodents at levels much higher than humans are currently exposed to, the link between cell phones and cancer in male rats was undeniable.
For female rats and mice of both sexes, the evidence was less clear as to whether cancers observed were associated with signal exposure.
Still, scientists warn that the new research suggests that men in particular should take precautions to minimize the exposure of sensitive areas to cell phone radiation.
Senior scientist Dr John Bucher at the National Toxicology Program (NTP) in Durham, North Carolina said: 'The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone.
'In our studies, rats and mice received radio frequency radiation (RFR) across their whole bodies.
'By contrast, people are mostly exposed in specific local tissues close to where they hold the phone.
'In addition, the exposure levels and durations in our studies were greater than what people experience.'
The finding was the result of a $30 million 10-year study to assess the health effects in animals exposed to RFR with modulations used in 2G and 3G cell phones.
The final reports represent the consensus of NTP and a panel of external scientific experts who reviewed the studies in March after draft reports were issued in February.
Dr Bucher explained: 'Cell phones utilize a specific type of radio waves, or radio frequency radiation (RFR), to transmit between the devices and the network.
'Exposure of people to RFR occurs primarily through use of cell phones and other wireless devices.'
The newly-published study focused on 2G and 3G technology. Now, cell service companies have moved on up to 4G, LTE and are rolling out 5G.