Medical/biological study (experimental study)

Deterioration of bone quality by long-term magnetic field with extremely low frequency in rats med./bio.

By: Gurgul S, Erdal N, Yilmaz SN, Yildiz A, Ankarali H

Published in: Bone 2008; 42 (1): 74-80

Aim of study (acc. to author)

The aim of this study was to investigate the effects of chronic (45 days) 50 Hz, 1 mT magnetic field exposure on femur biomechanical parameters of rats.

Background/further details

Altogether twenty-four, 8-week-old healthy rats, seven female and male each in the exposure group and five female and male each in the control group, were used.

Endpoint

morphol./histopathol. changes: biomechanical parameters of the bone

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 4 h/day for 45 days	magnetic flux density: 1 mT (+/- 0.05 mT) electric field strength: 4.37 mV/m

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	4 h/day for 45 days

Exposure setup

Exposure source	Helmholtz coils
Chamber	70 cm x 65 cm x 65 cm Faraday cage
Setup	pairs of circular Helmholtz coils with a diameter of 42.75 cm, a clearance of 21.375 cm and 160 turns of 2.2 mm insulated copper wire; rats placed in 26 cm x 17 cm x 13 cm polycarbonate cages in the center of the coils
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1 mT	-	measured	-	+/- 0.05 mT
electric field strength	4.37 mV/m	-	calculated	-	-

Exposed system:

animal
rat/Wistar albino
whole body

Methods Endpoint/measurement parameters/methodology

morphol./histopathol. changes: bone mineral density (dual-energy X-ray absorptiometry (DXA)); cross-sectional area of the femoral shaft (computed tomography); femur length; biomechanical measurements of the mid-diaphysis of the left femur: maximum load, displacement, stiffness, energy absorption capacity, ultimate stress, ultimate strain, elastic modulus and toughness (tensile test); diaphysial cortical bone thickness of the right femur (hematoxylin-eosin stain, light microscopy)

Investigated system:

tissue slices
femur

Investigated organ system:

muscular/skeletal system

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The bone mineral density, cortical thickness and cross-sectional area values of the femurs were significantly decreased in magnetic field exposed rats.
The biomechanical bone parameters maximum load, displacement, stiffness, ultimate stress, and elastic modulus values of magnetic field exposed rats were significantly decreased. Statistically significant less absorbed energy was observed in femurs of magnetic field exposed male rats. Ultimate strain was higher in exposed rats than that in control groups. The mean of toughness was decreased in exposed rats.
Histological examinations revealed normal bone structure in the control groups and irregular separations and blanks in exposed rats, especially in male animals.
In conclusion, these results indicate that the bone quality of rats is decreased by magnetic field exposure.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Mersin University, Turkey

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