Study type: Medical/biological study (experimental study)

Radiofrequency (microwave) radiation exposure of mammalian cells during UV-induced DNA repair synthesis. med./bio.

Published in: Radiat Res 1987; 110 (2): 255-266

Aim of study (acc. to author)

To investigate the effect of continuous wave (CW) and pulsed wave (PW) radiofrequency radiation in the microwave range on UV-induced DNA repair in normal human diploid fibroblasts.
The first question was whether, immediately after UV light irradiation, radiofrequency radiation at low power densities would interfere with at least one of the steps occuring in the DNA repair process. The second question was wether radiofrequency exposure by itself, without any UV preexposure, was capable of inducing DNA repair and the third question was whether pulsed wave radiofrequency radiation (medium temperature at constant 39°C), could affect incorporation of precursor radioactivity into cellular DNA by normal semiconservative synthesis.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 350 MHz
Modulation type: pulsed, CW
Exposure duration: 1, 2 or 3 h
Exposure 2: 850 MHz
Modulation type: pulsed, CW
Exposure duration: 3 h
  • SAR: 600 µW/g unspecified (to 9.9 W/kg; in the square dishes.)
  • power density: 100 W/m² mean
  • SAR: 4.5 mW/g mean (+/- 3.0 W/kg; at 10 mW/cm²; in the square dishes.)
Exposure 3: 850 MHz
Modulation type: pulsed, CW
Exposure duration: 3 h
-
Exposure 4: 1.2 GHz
Modulation type: pulsed, CW
Exposure duration: 3 h
  • SAR: 2.7 mW/g mean (+/- 1.6 W/kg; in the square dishes; at 10 mW/cm².)
  • power density: 100 W/m² mean
  • SAR: 700 µW/g unspecified (to 7.3 W/kg; in the square dishes.)

Exposure 1

Main characteristics
Frequency 350 MHz
Type
Waveform
Exposure duration 1, 2 or 3 h
Modulation
Modulation type pulsed, CW
Pulse width 10 µs
Duty cycle 0.05 %
Repetition frequency 5,000 Hz
Additional info

Pulse/packet 1:20

Exposure setup
Exposure source
Setup Plexiglas dishes immersed into rectangular water baths.
Additional info TEM-cell for exposure and an identical TEM-cell for control were placed inside anechoic chamber serving as 37°C warm room.
Parameters
Measurand Value Type Method Mass Remarks
SAR 390 µW/g mean measured - in square dishes; +/- 0.15 W/kg at 10 mW/cm²
power density 50 W/m² mean measured - 10 mW/cm²; for PW exposure
power density 18 µW/cm² unspecified measured - to 0.71 mW/cm²; in the square dishes.

Exposure 2

Main characteristics
Frequency 850 MHz
Type
Waveform
Charakteristic
Exposure duration 3 h
Modulation
Modulation type pulsed, CW
Pulse width 10 µs
Duty cycle 0.05 %
Repetition frequency 5,000 Hz
Additional info

Pulse/packet 1:20

Exposure setup
Exposure source
Setup The incubation dishes were placed in a Plexiglas water bath.
Additional info Exposures preformed in anechoic chamber.
Parameters
Measurand Value Type Method Mass Remarks
SAR 600 µW/g unspecified measured - to 9.9 W/kg; in the square dishes.
power density 100 W/m² mean measured - -
SAR 4.5 mW/g mean measured - +/- 3.0 W/kg; at 10 mW/cm²; in the square dishes.

Exposure 3

Main characteristics
Frequency 850 MHz
Type
Waveform
Charakteristic
Exposure duration 3 h
Modulation
Modulation type pulsed, CW
Pulse width 100 µs
Duty cycle 0.5 %
Packets per second 5,000
Additional info

Pulse/packet 1:20

Exposure setup
Exposure source
Setup The incubation dishes were placed in a Plexiglas water bath.
Additional info Exposures preformed in anechoic chamber.
Parameters

No parameters are specified for this exposure.

Exposure 4

Main characteristics
Frequency 1.2 GHz
Type
Exposure duration 3 h
Additional info Near Field exposure
Modulation
Modulation type pulsed, CW
Pulse width 3 µs
Duty cycle 0.24 %
Repetition frequency 80,000 Hz
Additional info

Pulse/packet 1:4

Exposure setup
Exposure source
Setup The incubation dishes were placed in a Plexiglas water bath.
Additional info Exposures preformed in anechoic chamber.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2.7 mW/g mean measured - +/- 1.6 W/kg; in the square dishes; at 10 mW/cm².
power density 100 W/m² mean measured - -
SAR 700 µW/g unspecified measured - to 7.3 W/kg; in the square dishes.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Radiofrequency radiation for 1 to 3 h at 37°C (continuous wave or pulsed wave) had no effect on the rate of repair replication label incorporated into preexisting UV-damaged DNA. Pulsed wave radiation, with a constant temperature of 39°C at 350- and 850 MHz during the repair period after UV damage, also had no effect. Assay for induction of repair synthesis by radiofrequency exposure alone in non-UV irradiated cells was negative for the continuous wave (350-, 850-, and 1200-MHz) and pulsed wave radiofrequency radiation at 37°C and the 350- and 850-MHz radiofrequency radiation at 39°C. Radiofrequency exposure does not induce DNA repair under these experimental conditions. No effect on incorporation of [³H]thymidine into DNA undergoing semiconservative synthesis was observed in preliminary experiments (at 39°C and pulsed wave radiofrequency radiation at the frequencies of 350-, 850-, and 1200 MHz).

Study character:

Study funded by