LONDON -- The experience of retired Major David Underwood, that he could feel a buzzing sensation in what remained of his left arm when driving under power lines and near cell phone towers, led a University of Texas research team to conduct an experiment that appears to have confirmed his anecdotal evidence.
Underwood, an Iraq war veteran, had previously been injured by an improvised explosive device and had his left arm amputated. He reported extreme pain when roaming on his cellphone.
Although there have been anecdotal accounts of neuropathic pain due to radio frequency electromagnetic fields there has been no scientific evidence to support this until now. The evidence is in research conducted by associate professor Mario Romero-Ortega and published online in PLOS ONE in January.
The team worked on the premise that the formation of neuromas inflamed peripheral nerve bundles that often form due to injury could be sensitive to radio frequency EMF.
To test this, the team randomly assigned 20 rats into two groups one receiving a nerve injury simulating amputation, and the other group receiving a sham treatment. Once a week the rats were exposed for 10 minutes to RF EMF at a power density of about 750mW per square meter, equivalent to that at about 39 meters from cellphone tower.
The RF field was circularly polarized at a frequency of 915MHz and energy density of 756 plus/minus 8.5 mW/m2.
Researchers found that by the fourth week, 88 percent of subjects in the nerve-injured group demonstrated a behavioral pain response to the exposure, while only one subject in the other group exhibited pain at any time and that was during the first week.
Previously the accepted wisdom was that neuroma has to be present to evoke pain. But Texas team found that EM fields could produce a pain response prior to neuroma formation. "Our study provides evidence, for the first time, that subjects exposed to cellphone towers at low, regular levels can actually perceive pain. Our study also points to a specific nerve pathway that may contribute to our main finding," said Romero-Ortega, an associate professor of bioengineering at the university.