Study type: Medical/biological study (experimental study)

Marked increase in the teratogenicity of the combined administration of the industrial solvent 2-methoxyethanol and radiofrequency radiation in rats. med./bio.

Published in: Teratology 1991; 43 (6): 621-634

Aim of study (acc. to author)

To study whether concurrent exposure of rats to radiofrequency irradiation and the industrial solvent 2-methoxyethanol can enhance the developmental toxicity of either agent acting alone.

Background/further details

Preliminary dose-finding studies investigated the ability of various radiofrequency irradiation conditions and doses of 2-methoxyethanol to produce external malformations when administered on gestation day 13. Based on these preliminary studies, radiofrequency irradiation (sufficient to elevate rectal temperature to 42°C for 30 min) and 150 mg/kg 2-methoxyethanol administration were selected for the main study.
In the main study, pregnant rats were administered radiofrequency irradiation and distilled water gavage, 2-methoxyethanol gavage and sham exposure, radiofrequency exposure and 2-methoxyethanol gavage concurrently, or sham exposure and distilled water gavage. Pregnant animals were sacrificed on gestation day 20, and the offspring were examined for external malformations.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 10 MHz
Modulation type: CW
Exposure duration: until the rectal temperature increased to 42°C and a moderate incidence of external malformations were produced; total exposure time ca. 1 h
  • SAR: 0.8 W/kg minimum (unspecified)
  • SAR: 6.6 W/kg maximum (unspecified)

Exposure 1

Main characteristics
Frequency 10 MHz
Type
Charakteristic
Exposure duration until the rectal temperature increased to 42°C and a moderate incidence of external malformations were produced; total exposure time ca. 1 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber Forma scientific enviromental chamber maintained at 24°C and 50% humidity
Setup rats were exposed without anesthesia in cylindrical plexiglas holders with 12 mm holes; each rat was oriented with its long axis parallel to the incident electric field
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.8 W/kg minimum - unspecified -
SAR 6.6 W/kg maximum - unspecified -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Combined exposures enhanced the adverse effects produced by either experimental agent alone. Mean fetal malformations/litter increased from 14% after 2-methoxyethanol and sham exposure and 30% after radiofrequency irradiation and water gavage, to 76% after the combined treatment. In addition to a significant increase in the frequency of malformations, the severity of malformations also was enhanced by the combination treatment.
The study provided evidence of synergism between radiofrequency irradiation and 2-methoxyethanol administration, but additional research will be required to characterize the extent of synergism between these two agents. Potential interactive effects between chemical and physical agents need to be studied to determine the extent to which such interactions should impact occupational exposure standards.

Study character:

Study funded by

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