Study type: Medical/biological study (experimental study)

Neoplastic transformation of C3H/10T1/2 cells following exposure to 120-Hz modulated 2.45-GHz microwaves and phorbol ester tumor promoter. med./bio.

Published in: Radiat Res 1991; 126 (1): 65-72

Aim of study (acc. to author)

In a previous study (publication 862) a statistically significant enhancement of transformation response by TPA in cells exposed to 2.45 GHz microwaves was shown.
This study was intended to show that the enhancement of neoplastic transformation due to electromagnetic fields plus TPA is dependent on the level of electromagnetic radiation and is additive with doses of X-rays given as a cocarcinogen.

Background/further details

Actively growing cells were exposed for 24 h to 2.45-GHz microwaves with or without subsequent incubation in TPA (0.1 µg/ml). In separate experiments, a 24-h electromagnetic field exposure at 4.4 W/kg was preceded or followed by X-radiation at 0.5, 1, or 1.5 Gy (with or without subsequent incubation in TPA).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 24 h

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
Exposure duration continuous for 24 h
Modulation
Modulation type pulsed
Repetition frequency 120 Hz
Exposure setup
Exposure source
  • magnetron
Setup Culture flasks immersed in water-bath. The cellular attachment plane was located more than 20 wavelengths away from the source and was positioned perpendicularly to the direction of EM wave propagation, parallel to EM field polarization plane. Shielded sham control flasks were located at the bottom of the water bath at a depth of 11 cm.
Additional info In a separate experiment, samples were exposed to 4.4 W/kg and were irradiated to x-ray prior or after the exposure at 0.5, 1 or 1.5 Gy.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 18 V/m peak value estimated - 56 V/m and 120 V/m
magnetic flux density 90 nT peak value estimated - 0.27 µT and 0.56 µT
SAR 0.1 W/kg unspecified unspecified - cellular monolayers were placed 8.7 cm below water level
SAR 1 W/kg unspecified unspecified - cellular monolayers were placed 4.8 cm below water level
SAR 4.4 W/kg unspecified unspecified - cellular monolayers were placed 2.3 cm below water level

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

There were no significant effects of TPA or electromagnetic fields on plating efficiency, or on survival in combination with X-radiation.
The electromagnetic field or TPA exposure alone had no effect on induction of neoplastic transformation. However enhancement of transformation due to electromagnetic fields plus TPA was highly significant (synergistic dose-dependent effect). It ranged up to a level equivalent to that produced by 1.5 Gy of X-rays. The frequency of neoplastic transformation was dependent on the level of electromagnetic radiation and was additive with doses of X-rays given as a cocarcinogen.

Study character:

Study funded by

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