Study type: Medical/biological study (experimental study)

1439 MHz pulsed TDMA fields affect performance of rats in a T-maze task only when body temperature is elevated med./bio.

By: Yamaguchi H, Tsurita G, Ueno S, Watanabe S, Wake K, Taki M, Nagawa H
Published in: Bioelectromagnetics 2003; 24 (4): 223-230
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Aim of study (acc. to author)

To assess the effects on learning and memory in rats of short term (4 days) or long term (4 weeks) exposure to a pulsed 1439 MHz, time division multiple access (TDMA) field based on the personal digital cellular (PDC) system used in cellular phones.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.439 GHz
Modulation type: pulsed
Exposure duration: repeated daily exposure for 1 h/day for 4 days
  • power: 7.5 W average over time
  • SAR: 7.5 W/kg average over mass (brain)
  • SAR: 11 W/kg peak value (brain)
  • SAR: 1.7 W/kg average over mass (whole body)
  • SAR: 32 W/kg peak value (whole body)
Exposure 2: 1.439 GHz
Modulation type: pulsed
Exposure duration: repeated daily exposure for 45 min/day for 4 days
  • power: 25 W average over time
  • SAR: 25 W/kg average over mass (brain)
  • SAR: 39 W/kg peak value (brain)
  • SAR: 5.7 W/kg average over mass (whole body)
  • SAR: 110 W/kg peak value (whole body)
Exposure 3: 1.439 GHz
Modulation type: pulsed
Exposure duration: repeated daily exposure for 1 h/day for 5 days and 2 days of rest for 4 weeks
  • power: 7.5 W average over time
  • SAR: 7.5 W/kg average over mass (brain)
  • SAR: 11 W/kg peak value (brain)
  • SAR: 1.7 W/kg average over mass (whole body)
  • SAR: 32 W/kg peak value (whole body)

Exposure 1

Main characteristics
Frequency 1.439 GHz
Type
Charakteristic
Exposure duration repeated daily exposure for 1 h/day for 4 days
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33.33 %
Packets per second 50
Additional info

Japanese digital standard PDC system
Exposure setup
Exposure source
Chamber The exposure system was based on a previous report and had been used in a previous study (see reference articles). In brief, the system consisted of a small anechoic chamber, a round turntable with eight tubes (28 cm in length, 6 cm in diameter), and a quarter wavelength monopole antenna on the floor.
Setup Four rats and four rat phantoms (artificial rat models), in alternate tubes, were positioned with their heads towards the central antenna.
Additional info Rats were divided into four groups: EM (7.5 W/kg), EM (25 W/kg), Sham and Cage. For sham exposure, an identical chamber was used, located inside the same shielded room.
Parameters
Measurand Value Type Method Mass Remarks
power 7.5 W average over time - - -
SAR 7.5 W/kg average over mass measured and calculated brain -
SAR 11 W/kg peak value measured and calculated brain -
SAR 1.7 W/kg average over mass measured and calculated whole body -
SAR 32 W/kg peak value measured and calculated whole body -
Measurement and calculation details

SARs in the rats were calculated by the FDTD method with numerical rat models and validated by measuring the temperature increase in the rat phantom.

Exposure 2

Main characteristics
Frequency 1.439 GHz
Type
Charakteristic
Exposure duration repeated daily exposure for 45 min/day for 4 days
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33.33 %
Packets per second 50
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power 25 W average over time - - -
SAR 25 W/kg average over mass measured and calculated brain -
SAR 39 W/kg peak value measured and calculated brain -
SAR 5.7 W/kg average over mass measured and calculated whole body -
SAR 110 W/kg peak value measured and calculated whole body -

Exposure 3

Main characteristics
Frequency 1.439 GHz
Type
Charakteristic
Exposure duration repeated daily exposure for 1 h/day for 5 days and 2 days of rest for 4 weeks
Modulation
Modulation type pulsed
Pulse width 6.7 ms
Duty cycle 33.33 %
Packets per second 50
Exposure setup
Exposure source
Additional info Rats were divided into three groups: EM (7.5 W/kg), Sham and Cage.
Parameters
Measurand Value Type Method Mass Remarks
power 7.5 W average over time - - -
SAR 7.5 W/kg average over mass measured and calculated brain -
SAR 11 W/kg peak value measured and calculated brain -
SAR 1.7 W/kg average over mass measured and calculated whole body -
SAR 32 W/kg peak value measured and calculated whole body -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The animals exposed to electromagnetic waves with the brain average SAR of 25 W/kg for 4 days showed statistically significant decreases in the transition in number of correct choices in the reversal task. However, rats exposed to the brain average SAR of 7.5 W/kg for either 4 days or for 4 weeks showed no T-maze performance impairments. In conclusion, exposure to a 1439 MHz TDMA field, as used in cellular phones, at SARs much stronger than those emitted by cellular phones did not affect the learning and memory processes of rats when exposure did not cause thermal effects.

Study character:

Study funded by

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