Study type: Medical/biological study (experimental study)

Lack of promoting effects of chronic exposure to 1.95-GHz W-CDMA signals for IMT-2000 cellular system on development of N-ethylnitrosourea-induced central nervous system tumors in F344 rats. med./bio.

Published in: Bioelectromagnetics 2007; 28 (7): 562-572

Aim of study (acc. to author)

To study the effects of a two year exposure to an electromagnetic near field equivalent to that generated by cellular phones on tumor development in the central nervous system of rats.

Background/further details

Pregnant rats were given a single administration of N-ethylnitrosourea on gestational day 18. A total of 500 pups were divided into five groups (each composed of 50 males and 50 females): Group 1, untreated control group; Group 2, N-ethylnitrosourea administration alone; Groups 3 to 5, N-ethylnitrosourea + electromagnetic field exposure (two levels) or sham exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.95 GHz
Exposure duration: repeated daily exposure, 90 min/day, 5 days/week, for 104 weeks, starting at 5 weeks of age
  • SAR: 0.67 W/kg average over mass (brain)
  • SAR: 3.1 W/kg peak value
  • SAR: 2 W/kg average over mass (brain)
  • SAR: 7.6 W/kg peak value
  • SAR: 0.464 W/kg maximum (whole body) (over 2 years)

Exposure 1

Main characteristics
Frequency 1.95 GHz
Type
Charakteristic
Exposure duration repeated daily exposure, 90 min/day, 5 days/week, for 104 weeks, starting at 5 weeks of age
Modulation
Modulation type cf. additional info
Additional info

W-CDMA for IMT-2000

Exposure setup
Exposure source
Distance between exposed object and exposure source 30 mm
Chamber The exposure apparatus was the same as applied for the experiment with 1.439-GHz EMF [Shirai et al., 2005], except for the length of the monopole antenna. The exposure box was 90 x 90 x 60 cm, the inside walls except for the ceiling being covered with electromagnetic absorber.
Setup Ten rats were fixed individually in plastic tubes of four different sizes (ID: 4.0, 4.7, 5.5, and 6.2 cm) and placed on disk-shaped plates like a carousel with their noses at 30 mm from a resonant monopole antenna at the center. Each plate was 65 cm in diameter, with adjustable height supported by a center hollow cylinder pole, and the distance between the ceiling and the rat backs was 5 mm.
Sham exposure A sham exposure was conducted.
Additional info Dummy animals were used to cover any vacancy and to maintain the symmetrical exposure conditions.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.67 W/kg average over mass calculated brain -
SAR 3.1 W/kg peak value calculated - -
SAR 2 W/kg average over mass calculated brain -
SAR 7.6 W/kg peak value calculated - -
SAR 0.464 W/kg maximum calculated whole body over 2 years

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)

The incidence and numbers of brain tumors in female rats exposed to the electromagnetic fields showed tendencies to increase but without statistical significance. Overall, no significant increase in incidences or numbers of CNS tumors, either in the male or female rats, was detected in the electromagnetic field exposed groups. In addition, no clear changes in tumor types in the brain were evident.
In conclusion, under these experimental conditions the data showed that exposure of heads of rats to 1.95 GHz W-CDMA signals for a two year period did not accelerate or otherwise affect N-ethylnitrosourea-initiated brain tumorigenesis.

Study character:

Study funded by

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