Study type: Medical/biological study (experimental study)

Modest increase in temperature affects ODC activity in L929 cells: Low-level radiofrequency radiation does not. med./bio.

Published in: Radiat Environ Biophys 2006; 45 (3): 231-235

Aim of study (acc. to author)

To study the effects of low-level radiofrequency irradiation and elevated temperature (< 1°C) on ornithine decarboxylase activity in murine fibroblasts.

Background/further details

Changing of culture medium and 50 Hz sine wave magnetic field (10 µT) were used as positive controls.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 2, 8 or 24 h
  • SAR: 0.2 W/kg (0.1-0.3 W/kg)
  • SAR: 0.4 W/kg (0.3-0.5 W/kg)
Exposure 2: 900 MHz
Modulation type: CW
Exposure duration: continuous for 2, 8 or 24 h
  • SAR: 0.2 W/kg (0.1-0.3 W/kg)
  • SAR: 0.4 W/kg (0.3-0.5 W/kg)

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2, 8 or 24 h
Modulation
Modulation type pulsed
Repetition frequency 217 Hz
Additional info

GSM modulation

Exposure setup
Exposure source
  • monopole
  • waveguide
  • see setup and chamber details
Chamber The waveguide exposure chamber was an aluminium RF resonator with a plastic cultivation chamber and a water circulation heat exchanger for keeping the temperature of the cell culture medium constant (± 0.3°C). The water circulated under a glass surface on which the cell-culture dishes were placed. Glass Petri dishes were used instead of plastic dishes for better thermal contact. There were two identical chambers, one for exposure and one for sham-exposure. However, the temperature of the water circulation heat exchanger in the exposure chamber (37.5 ± 0.3°C) was found to be, on average, 0.8°C higher than in the sham exposure chamber (36.7 ± 0.3°C), despite the temperature control. Warm air (approx. 37°C) and CO2 (5%) were fed into the cultivation chambers from a cell culture incubator.
Setup The RF power source consisted of a signal generator, a 217 Hz GSM modulator, and power amplifier. RF power was fed into the exposure chamber with a monopole post, and the electric field inside the chamber, below the heat exchanger, was monitored from another monopole post with an RF power meter.
Additional info Two Petri dishes were exposed simultaneously, and two dishes were sham-exposed. This was repeated 3-5 times at each exposure level and duration. In separate additional experiments, cells were incubated in ordinary cell culture incubators for 2 h at 37.6°C and 36.5°C measured with a Fluke thermometer and thermocouple in the medium. Magnetic fields were measured in both incubators to be 1.1 µT at 50 Hz at the position of the cell dishes. Cells were handled exactly in the same way as in the exposures in the waveguide system.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.2 W/kg - measured and calculated - 0.1-0.3 W/kg
SAR 0.4 W/kg - measured and calculated - 0.3-0.5 W/kg

Exposure 2

Main characteristics
Frequency 900 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2, 8 or 24 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.2 W/kg - measured and calculated - 0.1-0.3 W/kg
SAR 0.4 W/kg - measured and calculated - 0.3-0.5 W/kg

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Radiofrequency irradiation did not affect cellular ornithine decarboxylase activity. However, a slight increase in temperature (0.8-0.9°C) in the exposure system resulted in decreased ornithine decarboxylase activity in cell cultures. This was verified by tests in which cells were exposed to different temperatures in incubators (37.6°C and 36.5°C).
The data showed that ornithine decarboxylase activity is sensitive to small temperature differences in cell cultures.

Study character:

Study funded by

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