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Medical/biological study (experimental study)

Power-frequency magnetic fields at 50 Hz do not affect fertility and development in rats and mice.

Published in: Electromagn Biol Med 2018: 1-12 [in press]

Aim of study (acc. to author)

To investigate the effects of power frequency magnetic fields on fertility and development in rats and mice.
Background/further details: Rats: A total of 120 rats were randomly divided into four groups (n=30 per group; 15 females and 15 males, respectively): 1) sham exposure, 2) 30 µT magnetic field, 3) 100 µT magnetic field and 4) 500 µT magnetic field. Blood was taken before, after 12 and after 24 weeks of exposure to determine hormone concentrations (7 females and 7 males per group, respectively). Afterwards, rats were killed and reproductive organs were taken for further analyses (10 females and 10 males, respectively). Sperm count was performed in 5 males per group.
Several experiments were performed with mice:
Mice (hormones): 64 mice were randomly divided into the same four exposure groups as rats (n=16 per group; 8 females and 8 males, respectively). Blood was taken before and after exposure.
Mice (pregnancy rate): 315 mice were mated in different combinations (10 females and 5 males, respectively; experiments were independently repeated for three times): a) females group 1 x males group 1, b/c/d) females group 1 x males group 2/3/4, and e/f/g) females group 2/3/4 x males group 1 (same exposure groups as rats). Mice were mated after exposure. After 8 days of pregnancy, dams were killed and implanted embryos counted.
Mice (foetal development): 120 female and 60 male mice were mated and female mice were exposed to the above mentioned exposure groups afterwards (n=30 per group). On pregnancy day 18, dams were killed and fetuses examined.
Mice (development of pups): 60 female mice and 30 male mice were mated. The newborn pubs were randomly divided into the same four exposure groups as above (n=30 per group) and exposed for three weeks with their mothers.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 20 hours/day for 24 weeks
Exposure 2: 50 Hz
Exposure duration: 20 hours/day for 12 weeks
Mice (hormones)
Exposure 3: 50 Hz
Exposure duration: 20 hours/day for 8 weeks
Mice (pregnancy rate)
Exposure 4: 50 Hz
Exposure duration: 20 hours/day for 18 days
Mice (foetal development)
Exposure 5: 50 Hz
Exposure duration: 20 hours/day for 3 weeks
Mice (development of pups)
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Exposure duration 20 hours/day for 24 weeks
Additional info rats
Exposure setup
Exposure source
Chamber cages were made of plastic (length 45 cm x width 35 cm x height 20 cm); four rats per cage
Setup Four exposure devices (0, 30, 100, 500 µT) were run simultaneously but in different rooms; an exposure device consisted of five layers made with two beams of copper wires (length 200 cm x width 100 cm x height 200 cm); wires were fixed tightly to the framework to reduce vibration and noise; a plastic rack (140 cm x 70 cm x 200 cm) with 4 floors (each floor was 35 cm high) was set inside the exposure device; uniform area for magnetic flux density (± 3%) for each floor was 150 cm x 50 cm (length x width)
Sham exposure A sham exposure was conducted.
Additional info For sham exposure, animals were put in an exposure device without current
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -
magnetic flux density 100 µT - measured - -
magnetic flux density 500 µT - measured - -
Exposure 2
Main characteristics
Frequency 50 Hz
Type
Exposure duration 20 hours/day for 12 weeks
Additional info Mice (hormones)
Exposure setup
Exposure source
Chamber cages were made of plastic (length 25 cm x width 15 cm x height 12 cm); six mice per cage
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -
magnetic flux density 100 µT - measured - -
magnetic flux density 500 µT - measured - -
Exposure 3
Main characteristics
Frequency 50 Hz
Type
Exposure duration 20 hours/day for 8 weeks
Additional info Mice (pregnancy rate)
Exposure setup
Exposure source
Chamber cages were made of plastic (length 25 cm x width 15 cm x height 12 cm); six mice per cage
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -
magnetic flux density 100 µT - measured - -
magnetic flux density 500 µT - measured - -
Exposure 4
Main characteristics
Frequency 50 Hz
Type
Exposure duration 20 hours/day for 18 days
Additional info Mice (foetal development)
Exposure setup
Exposure source
Chamber cages were made of plastic (length 25 cm x width 15 cm x height 12 cm); six mice per cage
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -
magnetic flux density 100 µT - measured - -
magnetic flux density 500 µT - measured - -
Exposure 5
Main characteristics
Frequency 50 Hz
Type
Exposure duration 20 hours/day for 3 weeks
Additional info Mice (development of pups)
Exposure setup
Exposure source
Chamber cages were made of plastic (length 25 cm x width 15 cm x height 12 cm); six mice per cage
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - -
magnetic flux density 100 µT - measured - -
magnetic flux density 500 µT - measured - -
Reference articles
  • Lai J et al. (2016): Effects of 100 µT extremely low frequency electromagnetic fields exposure on hematograms and blood chemistry in rats.

Methods Endpoint/measurement parameters/methodology

Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

No significant differences were found between exposed rats and mice and sham exposed ones.
The authors conclude that power frequency magnetic fields did not have any influence on fertility and developmental parameters in mice.
Study character:

Study funded by

  • National Natural Science Foundation (NSFC), China
  • State Grid Corporation, China (SGCC)

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