Study type: Medical/biological study (experimental study)

DNA damage in Molt-4 T-lymphoblastoid cells exposed to cellular telephone radiofrequency fields in vitro med./bio.

By: Phillips JL, Ivaschuk O, Ishida-Jones T, Jones RA, Campbell-Beachler M, Haggren W
Published in: Bioelectrochem Bioenerg 1998; 45 (1): 103-110
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Aim of study (acc. to author)

To detect DNA single-strand breaks in lymphoblastoid cells exposed for short (2 and 3h) and long (21h) periods to pulsed signals at cellular telephones frequencies (813.5625 MHz and 836.55 MHz).

Background/further details

The studies were perfomed at low SAR to look for athermal radiofrequency radiation effects.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 813.5625 MHz
Modulation type: pulsed
Exposure duration: intermittent 20 min on/off for 2, 3 and 21 hours
Exposure 2: 836.55 MHz
Modulation type: pulsed
Exposure duration: intermittent 20 min on/off for 2, 3 and 21 hours

Exposure 1

Main characteristics
Frequency 813.5625 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent 20 min on/off for 2, 3 and 21 hours
Modulation
Modulation type pulsed
Pulse width 15 ms
Repetition frequency 22.22 Hz
Additional info

iDEN: time-domain multiplexing in which each second is broken down into a series of about 22 frames, each of 45 ms duration. Each frame is divided into three 15 ms slots. This results in RF carrier bursts of 15 ms duration, repeating at 45 ms intervals, at the mobile phone and the head of the user. The brief amplitude training pulse included at the leading edge of each slot is transmitted once every 200 frames (i.e. every 9 s) at 10 times the slot average power.
Exposure setup
Exposure source
Chamber Two TEM cells of 18 x 18 x 9 cm (both above and below the septum) were housed in a single incubator. They were each powered (exposed) or unpowered (sham).
Setup One 60-mm Petri dish with 5 ml of medium was placed on a 1.5 cm platform of styrene plastic which was placed centrally along the longitudinal axis on the septum in a region of reasonably uniform E-field normal to the dish.
Additional info The exposure pattern resulted in total exposure durations of 1, 1.67 and 10.67, respectively. There was no detectable rise in temperature at any power density used in these experiments. The ambient 60 Hz magnetic field outside the TEM cells was 0.13 ± 0.02 µT rms and 0.20 ± 0.04 µT rms.
Parameters
Measurand Value Type Method Mass Remarks
power 450 mW - measured - -
power density 0.8 mW/cm² - - - -
SAR 2.4 µW/g mean calculated - ± 0.3 µW/g
power 4.5 W - measured - -
SAR 24 µW/g mean calculated - -
Additional parameter details

SAR values indicated are slot averages.

Measurement and calculation details

The amplifier output was measured by a directional coupler, a power sensor and a power meter which was connected to a chart recorder for permanent recording. Before each series of experiments the power at the TEM cell input was confirmed with another power sensor and a digital power meter. The experimental conditions were based on dosimetric assessments for this system with exposure to iDEN performed by Kuster et al. (1996) using the MAFIA electromagnetic simulation tool (see second reference article).

Exposure 2

Main characteristics
Frequency 836.55 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent 20 min on/off for 2, 3 and 21 hours
Modulation
Modulation type pulsed
Additional info

North American Dual-Mode Cellular (NADC) with TDMA
Exposure setup
Exposure source
Additional info The exposure pattern resulted in total exposure durations of 1, 1.67 and 10.67, respectively.
Parameters
Measurand Value Type Method Mass Remarks
power 510 mW - measured - -
power density 0.9 mW/cm² - - - -
SAR 2.6 µW/g mean calculated - ± 1.9 µW/g
power 5.1 W - measured - -
SAR 26 µW/g mean calculated - -
Additional parameter details

SAR values indicated are slot averages.

Measurement and calculation details

A power meter/chart recorder combination connected to a directional coupler provided constant monitoring of forward power.

Reference articles

  • Ivaschuk OI et al. (1997): Exposure of nerve growth factor-treated PC12 rat pheochromocytoma cells to a modulated radiofrequency field at 836.55 MHz: effects on c-jun and c-fos expression
  • Burkhardt M et al. (1996): Numerical and experimental dosimetry of Petri dish exposure setups

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The results indicate that exposure of the cells to two different radiofrequency signals under athermal conditions altered the amount of DNA single-strand breaks. Exposure of cells to the iDEN signal (SAR of 2.4 µW/g, 2 or 21h) significantly decreased DNA damage and exposure at an SAR of 24 µW/g (2 or 21h) significantly increased DNA damage. Exposure of cells to the TDMA signal (SAR of 2.6 µW/g, 2 or 21h) and exposure at an SAR of 26 µW/g for 2h significantly decreased DNA damage.

Study character:

Study funded by

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