Section 4A: Safety Guidelines 248
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 when determining 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 the maximum measurement uncertainty
permitted by current measurement standards was added to the maximum
permissible SAR, the resulting SAR value would be well below any level known
to produce an acute effect. Consequently, FCC’s approach with measurement
uncertainty will not result in consumers being exposed to any known risk from
the RF emitted by cellular telephones.
FDA will continue to monitor studies and literature reports concerning acute
effects of cell phone RF, and concerning chronic effects of long-term exposure
to cellular telephone RF (that is, the risks from using a cell phone for many
years). If new information leads FDA to believe that a change to FCC’s
measurement policy may be appropriate, FDA will contact FCC and both
agencies will work together to develop a mutually-acceptable approach.
