Message from the FDA
15
Do wireless phone accessories that claim to shield the head from RF
radiation work?
Since there are no known risks from exposure to RF emissions from wireless phones,
there is no reason to believe that accessories that claim to shield the head from
those emissions reduce risks. Some products that claim to shield the user from RF
absorption use special phone cases, while others involve nothing more than a
metallic accessory attached to the phone. Studies have shown that these products
generally do not work as advertised. Unlike "hand-free" kits, these so-called "shields"
may interfere with proper operation of the phone. The phone may be forced to boost
its power to compensate, leading to an increase in RF absorption. In February 2002,
the Federal trade Commission (FTC) charged two companies that sold devices that
claimed to protect wireless phone users from radiation with making false and
unsubstantiated claims. According to FTC, these defendants lacked a reasonable
basis to substantiate their claim.
How does FCC Audit Cell Phone RF?
After FCC grants permission for a particular cellular telephone to be marketed, FCC will
occasionally conduct “post-grant” testing to determine whether production versions
of the phone are being produced to conform with FCC regulatory requirements. The
manufacturer of a cell phone that does not meet FCC’s regulatory requirements
may be required to remove the cell phone from use and to refund the purchase price
or provide a replacement phone, and may be subject to civil or criminal penalties.
In addition, if the cell phone presents a risk of injury to the user, FDA may also
take regulatory action. The most important post-grant test, from a consumer’s
perspective, is testing of the RF emissions of the phone. FCC measures the Specific
Absorption Rate (SAR) of the phone, following a very rigorous testing protocol.
As is true for nearly any scientific measurement, there is a possibility that the test
measurement may be less than or greater than the actual RF emitted by the phone.
This difference between the RF test measurement and actual RF emission is because
test measurements are limited by instrument accuracy, because test measurement
and actual use environments are different, and other variable factors. This inherent
variability is known as “measurement uncertainty.” When FCC conducts post-grant
testing of a cell phone, FCC takes into account any measurement uncertainty to
determine whether regulatory action is appropriate. This approach ensures that
when FCC takes regulatory action, it will have a sound, defensible scientific basis.
FDA scientific staff reviewed the methodology used by FCC to measure cell phone
RF, and agreed it is an acceptable approach, given our current understanding of the
risks presented by cellular phone RF emissions. RF emissions from cellular phones
have not been shown to present a risk of injury to the user when the measured SAR
is less than the safety limits set by FCC (an SAR of 1.6 w/kg). Even in a case where
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