Study type: Medical/biological study (experimental study)

A study on biological effects of low-intensity millimeter waves. med./bio.

Published in: IEEE Trans Plasma Sci IEEE Nucl Plasma Sci Soc 2002; 30 (4): 1489-1496

Aim of study (acc. to author)

To study the non-thermal effects of millimeter waves in the frequency range from 41-43 GHz on the growth rate and the absorption spectrum of Escherichia coli. In addition, the effect of this exposure on DNA was studied by measuring plasmid transformation efficiency.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 41–43 GHz
Exposure duration: continuous for 40 min.
growth rate experiment
Exposure 2: 41.3–41.9 GHz
Exposure duration: not given in the article
-
Exposure 3: 41–41.7 GHz
Exposure duration: continuous for 15 min.
transformation efficiency

Exposure 1

Main characteristics
Frequency 41–43 GHz
Type
Exposure duration continuous for 40 min.
Additional info growth rate experiment
Exposure setup
Exposure source
Setup 1 cm thick piece of Styrofoam placed on top of the pyramidal horn antenna in the anechoic chamber; samples positioned on top of the Styrofoam - one sample in a well in the center of the horn, the other in the adjacent well of a 12-well culture plate
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 32 mW/cm² - calculated - for the sample in the center
power density 2.6 mW/cm² - calculated - for the second sample

Exposure 2

Main characteristics
Frequency 41.3–41.9 GHz
Type
Exposure duration not given in the article
Additional info relative absorption spectrum of millimeter waves
Exposure setup
Exposure source
Setup E. coli suspension distributed on a 6 mm x 3 mm rectangle of a 8 mm x 5 mm filter paper with a thickness of 0.17 mm; filter paper placed between two flanges in the path of the millimeter wave
Parameters

No parameters are specified for this exposure.

Exposure 3

Main characteristics
Frequency 41–41.7 GHz
Type
Exposure duration continuous for 15 min.
Additional info transformation efficiency
Additional info frequency raised in 0.1 GHz steps
Exposure setup
Exposure source
Setup a 25 µ l volume of the plasmid was added to one well of a 96-well microtitre plate
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 12 mW/cm² - calculated - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The data did not show any statistically significant frequency-dependent effects on the growth of bacteria, nor any frequency-dependent effects on the DNA plasmid transformation efficiency. The only indication for resonant effects was found in the absorption spectrum of Escherichia coli. However, in control experiments and by changing the length of the waveguides in the millimeter wave system, the resonant-like absorption was found to be caused by the millimeter wave system itself.
The findings indicate that resonance effects are unlikely in this particular frequency range.

Study character:

Study funded by

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