Study type: Medical/biological study (experimental study)

Extremely Low-Frequency Magnetic Fields Induce Developmental Toxicity and Apoptosis in Zebrafish (Danio rerio) Embryos. med./bio.

Published in: Biol Trace Elem Res 2014; 162 (1-3): 324-332

Aim of study (acc. to author)

To examine potential biological effects of extremely low frequency magnetic fields on the development of zebrafish embryos.

Background/further details

Fish embryos were divided into seven groups: 1.) no treatment ("cage control"), 2.) sham exposure, 3.) 30 µT magnetic field exposure, 4.) 100 µT magnetic field exposure, 5.) 200 µT magnetic field exposure, 6.) 400 µT magnetic field exposure and 7.) 800 µT µT magnetic field exposure. Directly after fertilization of the eggs, exposure was started.
Per group, three dishes with embryos were used. For every examination, 10 embryos were randomly chosen from each dish.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 96 hours

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 96 hours
Exposure setup
Exposure source
Chamber zebrafish embryos were cultured in dishes in the center of the coils
Setup square Helmholtz coils were used to generate the magnetic field, each consisting of 100 turns of 1.5-mm diameter copper wire; 50 Hz AC current was allowed to pass through a variable voltage transformer, producing a relatively homogeneous 50-Hz magnetic field; magnetic field strength was axial and was parallel to the coil axis
Sham exposure A sham exposure was conducted.
Additional info sham group was conducted with coils similar to those in the exposure system, but without electricity passing through the coils
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 30 µT - measured - less than 1% spatial variation (calculated)
magnetic flux density 100 µT - measured - less than 1% spatial variation (calculated)
magnetic flux density 200 µT - measured - less than 1% spatial variation (calculated)
magnetic flux density 400 µT - measured - less than 1% spatial variation (calculated)
magnetic flux density 800 µT - measured - less than 1% spatial variation (calculated)

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

No significant differences regarding mortality and malformations were found between the groups. However, in the exposed groups 5, 6, and 7 (magnetic flux density of 200 µT and higher) a significantly delayed hatching and a significantly decreased heart rate in the early developmental stages was observed compared to the control groups (group 1 and 2). In the exposed embryos of the groups 5, 6, and 7, considerable signs of apoptosis were found mainly in the ventral fin and spinal column, which were not present in the control embryos. This finding was confirmed by a significant up-regulation of caspase-3 in the exposed groups 5, 6, and 7 and of caspase-9 in group 7 in comparison to the control.
The authors conclude that extremely low frequency magnetic fields have a detrimental effect on the development of zebrafish embryos.

Study character:

Study funded by

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