Study type: Medical/biological study (experimental study)

Interactions of radiofrequency radiation-induced hyperthermia and 2-methoxyethanol teratogenicity in rats med./bio.

By: Nelson BK, Conover DL, Krieg Jr EF, Snyder DL, Edwards RM
Published in: Bioelectromagnetics 1997; 18 (5): 349-359
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Aim of study (acc. to author)

The authors demonstrated in previous studies that combined exposure to radiofrequency irradiation (10 MHz) and the industrial solvent, 2-methoxyethanol, produces enhanced teratogenicity in rats (see publication 3522 and publication 3519).
The purpose of the present study was to determine the effects of varying the degree and duration of hyperthermia induced by radiofrequency irradiation (sufficient to maintain colonic temperatures at control [38.5], 39.0, 40.0, or 41.0°C for up to 6 h) and 2-methoxyethanol administered on gestation day 13 of rats.

Background/further details

Focusing on characterizing the dose-response pattern of interactions, this investigation seeks to determine the lowest interactive effect level.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 10 MHz
Modulation type: CW
Exposure duration: continuous for 2, 4 or 6 h
Target colonic temperature was set to 39°C
  • SAR: 7.9 W/kg mean (whole body) (applied initially to raise the temperature from 38.5°C to 39°C, 40°C or 41°C (20 min approximately))
  • SAR: 0.8 W/kg mean (whole body) (to 7.9 W/kg; SAR was adjusted to maintain the target temperature)
Exposure 2: 10 MHz
Modulation type: CW
Exposure duration: continuous for 1, 2, 3 or 4 h
Target colonic temperature was set to 40°C
  • SAR: 7.9 W/kg mean (whole body) (same remark as in E1)
  • SAR: 0.8 W/kg mean (whole body) (same remark as in E1)
Exposure 3: 10 MHz
Modulation type: CW
Exposure duration: continuous for 1 h
Target colonic temperature was set to 41°C
  • SAR: 7.9 W/kg mean (whole body) (same remark as in E1)
  • SAR: 0.8 W/kg mean (whole body) (same remark as in E1)

Exposure 1

Main characteristics
Frequency 10 MHz
Type
Charakteristic
Exposure duration continuous for 2, 4 or 6 h
Additional info Target colonic temperature was set to 39°C
Additional info Target colonic temperature was set to 39°C.
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber Near field synthesizers enclosed within copper wire chambers housed in Forma 7010 or 74668 environmental chambers
Setup Rats placed in cylindrical Plexiglas holders with 12 mm holes which was placed on a Plexiglas table. The holders were designed to prevent the rat from changing its orientation. Each rat was oriented in its long axis for induced electric field to be parallel.
Parameters
Measurand Value Type Method Mass Remarks
SAR 7.9 W/kg mean measured and calculated whole body applied initially to raise the temperature from 38.5°C to 39°C, 40°C or 41°C (20 min approximately)
SAR 0.8 W/kg mean measured and calculated whole body to 7.9 W/kg; SAR was adjusted to maintain the target temperature
Additional parameter details

In the sham exposure chamber 60 Hz EF were 0.17 to 0.20 V/m and 60 Hz MF ranged from 0.05 to 0.18 µT.

Exposure 2

Main characteristics
Frequency 10 MHz
Type
Charakteristic
Exposure duration continuous for 1, 2, 3 or 4 h
Additional info Target colonic temperature was set to 40°C
Additional info Target colonic temperature was set to 40°C.
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 7.9 W/kg mean measured and calculated whole body same remark as in E1
SAR 0.8 W/kg mean measured and calculated whole body same remark as in E1

Exposure 3

Main characteristics
Frequency 10 MHz
Type
Charakteristic
Exposure duration continuous for 1 h
Additional info Target colonic temperature was set to 41°C
Additional info Target colonic temperature was set to 41°C.
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 7.9 W/kg mean measured and calculated whole body same remark as in E1
SAR 0.8 W/kg mean measured and calculated whole body same remark as in E1

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The findings are consistent with previous observations. Significant interactions were observed between 2-methoxyethanol and radiofrequency irradiation sufficient to maintain colonic temperatures at 41°C for 1 h, but no consistent interactions were revealed at lower temperatures even with longer durations. These findings indicate that combined exposure effects should be considered when developing both radiofrequency irradiation and chemical exposure guidelines.

Study character:

Study funded by

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