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reduce the absorption of RF energy in the head because the
phone, which is the source of the RF emissions, will not be
placed against the head. On the other hand, if the phone is
mounted against the waist or other part of the body during use,
then that part of the body will absorb more RF energy. Wireless
phones marketed in the U.S. are required to meet safety
requirements regardless of whether they are used against the
head or against the body. Either configuration should result in
compliance with the safety limit.
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.
What about wireless phone interference with
medical equipment?
Radio frequency energy (RF) from wireless phones can interact
with some electronic devices. For this reason, FDA helped
develop a detailed test method to measure electromagnetic
interference (EMI) of implanted cardiac pacemakers and
defibrillators from wireless telephones. This test method is now
part of a standard sponsored by the Association for the
Advancement of Medical instrumentation (AAMI). The final draft,
a joint effort by FDA, medical device manufacturers, and many
other groups, was completed in late 2000. This standard will
allow manufacturers to ensure that cardiac pacemakers and
defibrillators are safe from wireless phone EMI. FDA has tested
wireless phones and helped develop a voluntary standard
sponsored by the Institute of Electrical and Electronic Engineers
(IEEE). This standard specifies test methods and performance
requirements for hearing aids and wireless phones so that no
interference occurs when a person uses a compatible phone and
a compatible hearing aid at the same time. This standard was
approved by the IEEE in 2000.
