Study type: Medical/biological study (experimental study)

Chronic exposure to 50-Hz magnetic fields or 900-MHz electromagnetic fields does not alter nocturnal 6-hydroxymelatonin sulfate secretion in CBA/S mice. med./bio.

Published in: Electro Magnetobiol 1999; 18 (1): 33-42

Aim of study (acc. to author)

To study whether chronic (over 17 months) exposure to vertical 50 Hz magnetic fields with regularly varying intensity affects noturnal 6-OHMS (6-hydroxymelatoninsulfate) production in female mice (n=140). The effects of 900 MHz radiofrequency irradiation were also studied.

Background/further details

The experiment was performed in the context of a long-term animal study on cancer-promoting effects of radiofrequency irradiation or 50 Hz magnetic field in mice after initiation with ionizing radiation. Therefore, groups were exposed at the beginning to ionizing radiation (4 Gy delivered as three sub-doses at 1 week intervals).
Artificial lighting was used with darkness from 7:00 p.m. to 7:00 a.m (15 to 180 lux).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 17 months
Exposure 2: 902.5 MHz
Modulation type: CW
Exposure duration: repeated daily exposure, 1.5 h/day, 5 days/week, for 17 months
  • SAR: 1.5 W/kg mean (whole body) (1.0-1.8 W/kg)
Exposure 3: 902.4 MHz
Modulation type: pulsed
Exposure duration: repeated daily exposure, 1.5 h/day, 5 days/week, for 17 months
  • SAR: 0.35 W/kg mean (whole body) (0.20-0.45 W/kg)

General information

Female mice were randomly divided into six treatment groups (50 per group in 8 cages): cage control, sham RF, CW RF, pulsed RF, sham ELF, and ELF. All groups, except cage controls, were at the beginning exposed to 4 Gy ionising radiation delivered in three sub-doses at 1 week intervals.

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 17 months
Exposure setup
Exposure source
Chamber The animals were housed in groups of six or seven in plastic Macrolon III cages (with aspen chip bedding) that were rotated weekly.
Setup The exposure system consisted of a wooden rack with 5 rectangular (0.4 x 1.2 m) coils producing a vertical homogeneous (±5%) magnetic field. The coils at the top and bottom had 15 turns, three middle coils had 10 turns. The vertical distances between the coils were 0.26 m.
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.3 µT unspecified measured - -
magnetic flux density 13 µT unspecified measured - -
magnetic flux density 130 µT unspecified measured - -

Exposure 2

Main characteristics
Frequency 902.5 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 1.5 h/day, 5 days/week, for 17 months
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber Three identical rectangular waveguides (24.8 x 20 cm, 125 cm long, and 190 cm with adapters) were used for CW, pulsed wave (E3) and sham exposures, respectively.
Setup Up to 25 mice per waveguide were individually kept in small acrylic restrainers (32 mm diameter, adjustable length). Average weight phantoms filled with a sugar/salt/water solution [Hartsgrove et al., 1987] were put in the empty places.
Sham exposure A sham exposure was conducted.
Additional info The animal positions were randomised before each exposure because the location-dependent SAR variation was ±30%.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.5 W/kg mean determined by power loss whole body 1.0-1.8 W/kg

Exposure 3

Main characteristics
Frequency 902.4 MHz
Type
Charakteristic
  • guided field
Exposure duration repeated daily exposure, 1.5 h/day, 5 days/week, for 17 months
Modulation
Modulation type pulsed
Duty cycle 12.5 %
Repetition frequency 217 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.35 W/kg mean determined by power loss whole body 0.20-0.45 W/kg

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Neither the extremely low frequency magnetic field nor the radiofrequency irradiation affected excretion of 6-OHMS in nocturnal urine.

Study character:

Study funded by

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