Study type: Medical/biological study (experimental study)

Nonthermal effects of mobile-phone frequency microwaves on uteroplacental functions in pregnant rats med./bio.

Published in: Reprod Toxicol 2003; 17 (3): 321-326

Aim of study (acc. to author)

To investigate the effects in pregnant rats exposed to non-thermal 915 MHz microwaves.

Background/further details

In six different treatment groups a total of 36 rats were examined: 1.) rats exposed to microwaves at 0.6 mW/cm2, 2.) rats exposed to microwaves at 3 mW/cm2, 3.) rats immersed in water at 38°C (induced the same colonic temperature increase as the group exposed to 0.6 mW/cm2 microwaves), 4.) rats immersed in water at 40°C (induced the same colonic temperature increase as the group exposed to 3 mW/cm2 microwaves), 5.) rats immersed in 34°C water (considered to be thermo-neutral), 6.) control rats.



Exposure Parameters
Exposure 1: 915 MHz
Modulation type: CW
Exposure duration: continuous for 90 min

Exposure 1

Main characteristics
Frequency 915 MHz
Exposure duration continuous for 90 min
Additional info Padilla JM, Bixby RR. Using Dewar flask calorimetry and rectal temperatures to determine the SARs of small rodents. USAFSAM-TP-86-3. TX, USA: Brooks AFB 1986.
Modulation type CW
Exposure setup
Exposure source
  • magnetron, applicator (350 mm x 470 mm x 455 mm)
Chamber The environment of the exposure facility was maintained at 21-23 °C and 50-60% humidity.
Setup Rats were placed individually into semi-cylindrical acrylic plastic holders (inner diameter 60 mm, length 170 mm, walls 5 mm) and exposed in the device described previously [Inaba et al., 1992]. Two holders were put into the applicator with their long axis oriented parallel to the electric field.
Additional info Rats were assigned to six groups: exposed to EMF at 0.6 or 3 mW/cm²; immersed in water at 38, 40 °C (inducing about the same increase in colonic temperature as the EMF) or at 34 °C (thermoneutral) or in a control group.
Measurand Value Type Method Mass Remarks
power density 0.6 mW/cm² - measured - ±10%
SAR 0.4 W/kg - measured whole body -
power density 3 mW/cm² - measured - ±10%
SAR 2 W/kg - measured whole body -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Significant differences in the utero-placental circulation and in the placental endocrine functions between pregnant rats immersed in water at 34 and 38°C were identified, but not between rats immersed at 38°C and those exposed to microwaves at 0.6 mW/cm2. By contrast, significant decreases in the utero-placental blood flow and estradiol level in rats exposed to microwaves at 3 mW/cm2 as compared with those immersed in water at 40°C were observed. Therefore, microwaves at exposure levels that increase core temperature by about 3.5°C seem likely to produce utero-placental dysfunctions through thermal and nonthermal actions.
The microwave exposure to 0.6 mW/cm2 and water immersion at 38°C reduced splenic natural killer cell activity, but microwaves at 3 mW/cm2 did not change splenic natural killer cell activity as compared to the group exposed to 34°C water immersion.
In conclusion, the exposure to microwaves at 0.6 mW/cm2 (maximum permissible exposure level recommended by ANSI) do not exert nonthermal effects on the utero-placental blood flow, blood estriol and progesterone level, and splenic natural killer cell activity.

Study character:

Study funded by

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