S, Wrocklage C, Raczek J, et al.
studied the effect of a RF electromagnetic field on the nervous system
control of blood pressure. Ten young adults were sham-exposed to a phone
model fixed to the right side of the head for 35 minutes, and then exposed
to EMF at 900 MHz, pulse frequency 217 Hz, simulating a GSM phone system.
At the end of each period of sham exposure or exposure, blood pressure
was measured in the resting state, during standing for 60 seconds, and
during a Valsalva manoeuvre, which causes changes in the lung pressures
and in heart rate and blood pressure. Resting blood pressure was increased
by 5-10 mm Hg after EMF exposure. The authors speculate that these changes
were due to an increase in the sympathetic component of the autonomic
nervous system. There were no other significant differences between
the exposure and sham periods.
The main shortcoming of this study was the lack of randomization in the
sequence of sham-exposure and exposure. The sham exposure was always done