Context: The dramatic increase in use of cellular telephones has generated concern
about possible negative effects of radiofrequency signals delivered to the brain. However,
whether acute cell phone exposure affects the human brain is unclear.
Objective: To evaluate if acute cell phone exposure affects brain glucose metabolism,
a marker of brain activity.
Design, Setting, and Participants: Randomized crossover study conducted between
January 1 and December 31, 2009, at a single US laboratory among 47 healthy
participants recruited from the community. Cell phones were placed on the left and right
ears and positron emission tomography with (18F)fluorodeoxyglucose injection was used
to measure brain glucose metabolism twice, once with the right cell phone activated (sound
muted) for 50 minutes (on condition) and once with both cell phones deactivated (off
condition). Statistical parametric mapping was used to compare metabolism between on
and off conditions using paired t tests, and Pearson linear correlations were used to verify
the association of metabolism and estimated amplitude of radiofrequency-modulated electromagnetic
waves emitted by the cell phone. Clusters with at least 1000 voxels (volume
8 cm3) and P.05 (corrected for multiple comparisons) were considered significant.
Main Outcome Measure: Brain glucose metabolism computed as absolute metabolism
(¼mol/100 g per minute) and as normalized metabolism (region/whole brain).
Results: Whole-brain metabolism did not differ between on and off conditions. In contrast,
metabolism in the region closest to the antenna (orbitofrontal cortex and temporal
pole) was significantly higher for on than off conditions (35.7 vs 33.3 ¼mol/100 g per
minute; mean difference, 2.4 [95% confidence interval, 0.67-4.2]; P=.004). The increases
were significantly correlated with the estimated electromagnetic field amplitudes both for
absolute metabolism (R=0.95, P.001) and normalized metabolism (R=0.89; P.001).
Conclusions: In healthy participants and compared with no exposure, 50-minute cell
phone exposure was associated with increased brain glucose metabolism in the region
closest to the antenna. This finding is of unknown clinical significance.
JAMA. 2011;305(8):808-814 www.jama.com