Medical/biological study (experimental study)

14.6 mT ELF magnetic field exposure yields no DNA breaks in model system Salmonella, but provides evidence of heat stress protection med./bio.

By: Williams PA, Ingebretsen RJ, Dawson RJ

Published in: Bioelectromagnetics 2006; 27 (6): 445-450

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Aim of study (acc. to editor)

To study the effects of magnetic fields on DNA strand breaks in the bacterial Salmonella enterica test system.

Endpoint

genotoxicity/mutation: DNA strand breaks

Exposure

- 50/60 Hz
- magnetic field
- inhouse wiring
- other domestic appliance

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: intermittent, 5 min on/10 min off for 4 h	magnetic flux density: 14.6 mT peak value

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	intermittent, 5 min on/10 min off for 4 h

Exposure setup

Exposure source	solenoid
Setup	exposure system consisted of three units with 1 m long air core solenoids and one control unit; all four units were submerged in 37°C circulating deionized water; vertically aligned units were evenly spaced at 1 m so that the field interference was almost zero; ratio of solenoid length to the diameter of the core was so large that all three produced extremely uniform MF at region where the cultures were placed

Exposure source

solenoid

Setup

exposure system consisted of three units with 1 m long air core solenoids and one control unit; all four units were submerged in 37°C circulating deionized water; vertically aligned units were evenly spaced at 1 m so that the field interference was almost zero; ratio of solenoid length to the diameter of the core was so large that all three produced extremely uniform MF at region where the cultures were placed

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	14.6 mT	peak value	calibration	-	-

Additional parameter details

14.6 mT was chosen to maintain the cultures at 37°C growth temperature

Exposed system:

bacterium
Salmonella typhimurium/LT2 (TT22240; TT24257; TT24470)

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA strand breaks (recombination events (recombination event yields to chloramphenicol-sensitive recombinants and leads to white colonies on indicator plates; colony forming units); event counter assay)
cell viability/cell division/proliferation: cell viability (colony forming units)

Investigated system:

bacterium

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The data showed no significant increase in recombination events and strand breaks due to magnetic field.
Evidence of heat stress protection was determined by comparison of the survival rates of magnetic field exposed and control cells after the administration of a 10 min 53°C heat stress. The control cells exhibited nine times more cell mortality than the magnetic field exposed cells.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

RRW (Roger R. Williams) Research Foundation, Utah, USA

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