Medical/biological study (experimental study)

The effects of different intensities, frequencies and exposure times of extremely low-frequency electromagnetic fields on the growth of Staphylococcus aureus and Escherichia coli O157:H7 med./bio.

By: Bayir E, Bilgi E, Sendemir-Urkmez A, Hames-Kocabas EE

Published in: Electromagn Biol Med 2015; 34 (1): 14-18

Aim of study (acc. to author)

The effects of exposure of bacteria to different extremely low frequency magnetic fields on cell growth should be investigated.

Background/further details

Bacteria of the strains, Staphylococcus aureus and E. coli, were each exposed to magnetic fields with every combination of 3 different frequencies (20, 40 and 50 Hz) and 2 different magnetic flux densities (2 and 4 mT) for 4 different durations (1, 2, 4 and 6 h). For each exposure condition, a separate sham exposure was conducted and each exposure and respective sham exposure condition was tested 2 times and 4 plates per replicate were counted.

Endpoint

cell viability/cell division/proliferation: cell growth

Exposure

- 20–50 Hz
- 50/60 Hz
- magnetic field
- low frequency

Exposure	Parameters
Exposure 1: 20 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 2 mT
Exposure 2: 40 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 2 mT
Exposure 3: 50 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 2 mT
Exposure 4: 20 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 4 mT
Exposure 5: 40 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 4 mT
Exposure 6: 50 Hz Exposure duration: continuous for 1, 2, 4 or 6 hours	magnetic flux density: 4 mT

General information

the local geomagnetic field was measured as 32 ± 2.5 µT

Exposure 1

Main characteristics

Frequency	20 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	coil(s)
Chamber	Eppendorf tubes (1.5 ml)
Setup	tubes were placed in the middle of the coils; temperature inside the coil was maintained at 25 ± 0.5°C; no significant temperature change was detected between the activated coils during the trials; the field was homogeneous with a maximum of ± 3.5% deviation
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	2 mT	-	measured	-	-

Exposure 2

Main characteristics

Frequency	40 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	2 mT	-	measured	-	-

Exposure 3

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	2 mT	-	measured	-	-

Exposure 4

Main characteristics

Frequency	20 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	4 mT	-	measured	-	-

Exposure 5

Main characteristics

Frequency	40 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	4 mT	-	measured	-	-

Exposure 6

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 1, 2, 4 or 6 hours

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	4 mT	-	measured	-	-

Exposed system:

intact cell/cell culture
bacterium
Staphylococcus aureus and Escherichia coli O157:H7

Methods Endpoint/measurement parameters/methodology

cell viability/cell division/proliferation: cell growth (plating on agar before and after exposure, incubation for 24 hours, count of colony forming units)

Investigated system:

intact cell/cell culture

Time of investigation:

before exposure
after exposure

Main outcome of study (acc. to author)

In both strains and independently from the applied frequency and intensity of the magnetic field, a general trend towards a decreasing cell growth with increasing exposure duration was observed. Except for the exposure duration of 1 hour, which showed inconsistent results, all cells exposed for 2, 4 or 6 hours to a field of 20, 40 or 50 Hz and 2 or 4 mT showed a significantly decreased cell growth compared to the sham exposed cells.
Exposure to a 20 Hz field of 4 mT for 6 h produced the largest decrease in cell growth compared to the sham exposed cells.
The authors conclude that exposure of bacteria to different extremely low frequency magnetic fields could retard cell growth as a function of time.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

The Scientific and Technical Research Council of Turkey (TÜBITAK), Turkey

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The effects of different intensities, frequencies and exposure times of extremely low-frequency electromagnetic fields on the growth of Staphylococcus aureus and Escherichia coli O157:H7 med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

General information

Exposure 1

Main characteristics

Exposure setup

Parameters

Exposure 2

Main characteristics

Exposure setup

Parameters

Exposure 3

Main characteristics

Exposure setup

Parameters

Exposure 4

Main characteristics

Exposure setup

Parameters

Exposure 5

Main characteristics

Exposure setup

Parameters

Exposure 6

Main characteristics

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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