Are RF signals dangerous? Check the facts.

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  1. Tomi Engdahl says:

    Mobile device proximity sensor manages RF exposure while maintaining network connectivity

    The FCC last set U.S. mobile phone RF exposure limits in 1996, recommending a maximum of 1.6 watts per kilogram specific absorption rate (SAR). Back then, the Motorola StarTAC was the industry’s best selling phone, less than 20% of the country had mobile devices and when they did they wore them away from their bodies in belt holsters.

    A lot has changed now that we are in the smartphone era, starting with much higher RF power levels to support higher data rates and a more extensive range of smart mobile devices including smartphones, phablets and tablets. Usage of these devices is increasing dramatically. In a 2014 survey of consumers, research firm Nielsen discovered that American consumers spent 34 hours on average per month using the mobile apps on their phones – which is more time than they spent online via PC.

    This increased RF power and increased exposure has caused the industry to anticipate ways to better manage SAR reduction. Proximity sensors are one tool that have long been used in tablets to detect a user’s body before the device comes closer than the minimum distance (dmin) for safe use as defined by the FCC. Once the device reaches dmin, the proximity sensor can then trigger a reduction in RF power to limit the user’s RF exposure

    SAR and RF radiation have made headlines (2) recently with several high profile brain cancer deaths, even though there is not a scientific link between the two.

    city of Berkeley, Calif., recently passed a “right to know” law (3) that all cell phones sold in the city must be labeled with the SAR level and a warning. These headlines have raised some customer concern,

    One solution for managing SAR is to build a capacitive proximity sensor into a mobile device that can determine when the device is close to being in contact with parts of the body and can optimize the RF power to a level that reduces overall SAR, yet still lets the device stay connected to the network.

  2. Tomi Engdahl says:

    News & Analysis
    EM Fields From Cell Phone Masts Can Amplify Pain

    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,”

    “There are people who live in caves because they report themselves to be hypersensitive to RF electromagnetism, yet the rest of the world uses cellphones and does not have a problem. The polarization may allow people to disregard the complaints of the few as psychosomatic

    The next step is to try and develop devices that block neuropathic pain from RF electromagnetic energy


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