Study type: Medical/biological study (experimental study)

Effect of 99 GHz continuous millimeter wave electro-magnetic radiation on E. coli viability and metabolic activity. med./bio.

Published in: Int J Radiat Biol 2010; 86 (5): 390-399

Aim of study (acc. to author)

To study the dependence of exposure duration (1 h or 19 h) of continuous wave millimeter wave 99 GHz irradiation on Escherichia coli bacterial cell viability and metabolic activity.

Background/further details

All experiments were performed on Escherichia coli populations during the logarithmic phase. For cell viability tests two exposure methods were used: 1) exposure was conducted on cells that were spread on agar plates, and 2) exposure was conducted on cells that were suspended in two different culture mediums (PBS (to study the cell death) or LB (to study cell division)). For metabolic activity test exposure (19 h) was conducetd on cells that were suspended in LB medium.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 99 GHz
Modulation type: CW
Exposure duration: continuous for 1 h
Exposure 2: 99 GHz
Modulation type: CW
Exposure duration: continuous 1 h or 19 hr

Exposure 1

Main characteristics
Frequency 99 GHz
Type
Exposure duration continuous for 1 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 22 mm
Setup agar plate at a short distance from the antenna
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.17 mW/cm² - calculated - at the bacterial plane

Exposure 2

Main characteristics
Frequency 99 GHz
Type
Exposure duration continuous 1 h or 19 hr
Modulation
Modulation type CW
Exposure setup
Exposure source
Distance between exposed object and exposure source 0.5 cm
Setup bacterial suspensions placed above the antenna
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 0.2 mW/cm² - calculated - at the bacterial plane

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The data showed that 1 hour of exposure to 99 GHz continuous wave electromagnetic field irradiation had no effect on Escherichia coli viability and colony characterisation. In 19 h of exposure, the number of colony forming units was half order of magnitude higher than the sham exposed and the control: In exposed samples, the calculated viable cells in PBS and LB medium were 8.19 x 107 and 1.47 x 109 cells/ml, respectively. In the sham exposed samples, the calculated viable cells in PBS and LB medium were 3.47 x 107 and 8.41 x 108 cells/ml, respectively. However, 19 h of exposure did not affect the metabolic activity.
The authors conclude that exposure of Escherichia coli to millimeter wave 99 GHz irradiation (continuous wave) for a short period did not affect the viability of Escherichia coli bacterial cells. However, exposure for 19 h caused a slight proliferation but did not influence the metabolic activities (of about 90 biochemical reactions that were examined). Hence, the authors assume that the slight proliferation (half order of magnitude) after 19 h of exposure does not have a biological meaning.

Study character:

Study funded by

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