Study type: Medical/biological study (experimental study)

Lack of direct DNA damage in human blood leukocytes and lymphocytes after in vitro exposure to high power microwave pulses med./bio.

By: Chemeris NK, Gapeyev AB, Sirota NP, Gudkova OY, Tankanag AV, Konovalov IV, Buzoverya ME, Suvorov VG, Logunov VA
Published in: Bioelectromagnetics 2006; 27 (3): 197-203
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Aim of study (acc. to author)

To study the effects of high power microwave pulses on DNA of human blood leukocytes and isolated lymphocytes.

Background/further details

At the beginning of exposure, temperature of the cell suspension was 23+/-1°C. Then the temperature increased for 10-15 s to the steady state level of 27+/-1°C, which was unchanged until the end of exposure.
Temperature and negative controls were performed at 23+/-1°C (steady state temperature of the waveguide; negative control), at 27+/-1°C (temperature increment during exposure/temperature of the exposed samples = temperature control), and at 37°C (normal physiological temperature; negative control).
Positive controls were treated with the alkylating agent ethyl methanesulfonate.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 8.8 GHz
Modulation type: pulsed
Exposure duration: continuous for 40 min
  • SAR: 1.6 kW/kg average over time

Exposure 1

Main characteristics
Frequency 8.8 GHz
Charakteristic
  • guided field
Exposure duration continuous for 40 min
Additional info reference article: Lebedev IV. 1961. Techniques and devices for super high frequencies, Vol. 1 Moscow-Leningrad: Gosenergoizdat.
Modulation
Modulation type pulsed
Pulse width 180 ns
Rise time 10 ns
Fall time 33 ns
Repetition frequency 50 Hz
Pulse type rectangular
Exposure setup
Exposure source
  • waveguide
  • rectangular, 23 x 3.4 mm, see chamber and setup details
Chamber The cell suspension was exposed to high power microwave pulses (HPMP) in a special plastic cuvette of cylindrical shape with a diameter of 10 mm and a height of 1 mm. The cuvette was placed inside a rectangular waveguide (cross-section 23 x 3.4 mm) at a distance of 25-30 mm from a waveguide flange with the help of a special foam-plastic holder.
Additional info Calculations of the magnitude of the electric field in a rectangular waveguide operating in the H10 mode were carried out for the exterior and interior of the cuvette according to Lebedev [1961] (see reference article); the maximal magnitude of the electric field in the cuvette was about 70 kV/m.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.6 kW/kg average over time calculated - -
Additional parameter details

The average SAR of 1.6 kW/kg indicated applies to the center of the sample. Maximal SAR in the cell medium toward the microwave source was approximately by 1.7 times higher than the average SAR.

Measurement and calculation details

Temperature measurements were carried out in the cuvette filled with 50 µl of physiological saline using a copper-constantan micro-thermocouple with a diameter of 50 µm. The accuracy of temperature readings was ±0.1 °C. A thermocouple was inserted into a modified cuvette from the bottom through a narrow slot in a wide wall of the waveguide. A digital voltmeter was used for the measurements of voltage generated by a thermocouple. The time constant of the temperature measuring system was 0.05 s. The average initial rate of temperature rise was 0.37 ± 0.01 °C/s, which corresponded to the average SAR of 1.6 kW/kg (peak SAR was assessed as about 300 MW/kg).

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 reveal any statistically significant DNA damage manifested immediately after in vitro high power microwave pulses exposure of human blood leukocytes or lymphocytes or after high power microwave pulse exposure of leukocytes subsequently incubated at 37°C for 30 min compared to the respective negative (23 and 37°C) and temperature (27°C) controls.

Study character:

Study funded by

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