Study type: Medical/biological study (experimental study)

Effects of 7 Hz-modulated 450 MHz electromagnetic radiation on human performance in visual memory tasks med./bio.

By: Lass J, Tuulik V, Ferenets R, Riisalo R, Hinrikus H
Published in: Int J Radiat Biol 2002; 78 (10): 937-944
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Aim of study (acc. to author)

Effect of 7 Hz modulated 450 MHz radiation on human performance in visually presented neuropsychological tasks associated with attention and short-term memory.

Background/further details

A homogeneous group of 100 subjects (37 female, 63 male) were randomly divided into two groups (exposed or sham-exposed group).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 450 MHz
Modulation type: pulsed
Exposure duration: continuous for 10-20 min

Exposure 1

Main characteristics
Frequency 450 MHz
Type
Exposure duration continuous for 10-20 min
Modulation
Modulation type pulsed
Duty cycle 50 %
Repetition frequency 7 Hz
Exposure setup
Exposure source
Distance between exposed object and exposure source 10 cm
Chamber The subject was seated in a chair at the table using a PC monitor and a mouse.
Setup Exposure conditions were identical to those in previous work [Lass et al., 1999]. The antenna was located 10 cm from the skin on the right side of the head.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.158 mW/cm² - measured - at the cortex
SAR 9.5 mW/kg - calculated - in the brain
Measurement and calculation details

The SAR calculation inside the brain was based on the field power density on the skin measured by a field power density meter and monitored during the experiments by a field strength meter. The results of numerical calculations based on the digital anatomical model taking into account the frequency dependence and possible variations of tissue dielectric value and conductivity yielded a more reliable estimation of the whole body and localized SAR than the initially used formula SAR = σE2/2ρ. The levels of power density and SAR calculated by both methods were so low that thermal effects are extremely unlikely.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The results of the study provide additional evidence that acute low-level exposure to microwaves modulated at 7 Hz can affect cognitive processes such as attention and short-term memory. These effects caused a decrease in the number of errors for less complicated neuropsychological tasks and an increase in the errors of more complicated ones.

Study character:

Study funded by

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