Study type: Medical/biological study (experimental study)

Lack of effects of 1439 MHz electromagnetic near field exposure on the blood-brain barrier in immature and young rats med./bio.

By: Kuribayashi M, Wang J, Fujiwara O, Doi Y, Nabae K, Tamano S, Ogiso T, Asamoto M, Shirai T
Published in: Bioelectromagnetics 2005; 26 (7): 578-588
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Aim of study (acc. to author)

To study whether electromagnetic field exposure causes any damage of blood-brain barrier in rats with ages equivalent to the time of blood-brain barrier genesis and the young adult.

Background/further details

Immature (4 weeks old) and young (10 weeks old) rats were used.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1,439 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 90 min/day, 6 days/week, for 1 or 2 weeks
  • SAR: 2 W/kg average over mass (brain)
  • SAR: 6 W/kg average over mass (brain)
  • SAR: 0.29 W/kg maximum (whole body)

Exposure 1

Main characteristics
Frequency 1,439 MHz
Type
Charakteristic
Exposure duration repeated daily exposure, 90 min/day, 6 days/week, for 1 or 2 weeks
Additional info Wang J, Fujiwara O. 2004. A new method for realizing local exposure to young rat heads using electric flux concentration for bio-effect test of mobile telephones. Proceedings of the International Symposium on Electromagnetic Compatibility, Sendai, June 2004:581-584.
Modulation
Modulation type pulsed
Duty cycle 33 %
Repetition frequency 50 Hz
Additional info

TDMA signal for the PDC (Japanese cellular telephone standard) system
Exposure setup
Exposure source
Distance between exposed object and exposure source 3 cm
Chamber The exposure box (90 x 90 x 60 cm) was made of metal, and its walls were inlaid with pyramidal EM wave absorber, except for the metal roof, which formed the ground of the antenna installed vertically in its center [Shirai et al., 2005]. A disk-like plate was supported by a central hollow cylinder pole through which air was ventilated into the box.
Setup Rats were individually fixed in plastic holders and were set on the disk-shaped plate like a carrousel with their noses pointing to the central antenna at a distance of 3 cm. A flexible ferroelectric sheet, 1 mm thick, covering the head part of the plastic holder concentrated the electric flux in a circle which resulted in a strong magnetic field in the region of the rat head.
Sham exposure A sham exposure was conducted.
Additional info Ten exposure boxes were placed in a shielded room, and 10 rats were exposed at the same time with the same SAR. After one week, five rats in each group were sacrificed and replaced by live dummy rats (not used in any analysis) to maintain the exposure condition.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg average over mass measured and calculated brain -
SAR 6 W/kg average over mass measured and calculated brain -
SAR 0.29 W/kg maximum measured and calculated whole body -
Measurement and calculation details

SAR distribution in the brain and whole body of rats was determined numerically using the FDTD method with anatomically based rat models with a voxel size of 1 mm and 17 tissue types and was validated by measurements on a homogeneous gel phantom using an infrared image camera and fluor-optic temperature probes. The calculated and measured results were in good agreement [Wang and Fujiwara, 2004].

Reference articles

  • Shirai T et al. (2005): Chronic exposure to a 1.439 GHz electromagnetic field used for cellular phones does not promote N-ethylnitrosourea induced central nervous system tumors in F344 rats

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Although expression of the three genes was decreased after administration of 1,3-dinitrobenzene as a positive control, when compared with the control values, there were no pathologically relevant differences with the electromagnetic field at any exposure levels at either age. Vascular permeability, measured with reference to transfer of FITC-dextran, was not affected by electromagnetic field exposure.
Thus, these data indicate that local exposure of the head to 1439 MHz electromagnetic field exerts no adverse effects on the blood-brain barrier in immature and young rats.

Study character:

Study funded by

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