Medical/biological study (observational study)

Effect of extremely low frequency magnetic field on antioxidant activity in plasma and red blood cells in spot welders med./bio.

By: Sharifian A, Gharavi M, Pasalar P, Aminian O

Published in: Int Arch Occup Environ Health 2009; 82 (2): 259-266

Aim of study (acc. to author)

To determine a possible relation between exposure to extremely low frequency magnetic field and the human antioxidant activity.

Background/further details

46 male spot welders and a control group (n=45) from the same factory were examined (mean employment period = 3.8 years). Both groups were matched according to demographical characteristics, employment conditions and exclusion criteria. The workers were exposed to dynamic electromagnetic fields 40h/week (6 days/week). Prior to start of each working shift (following 12 h fasting), blood samples were obtained. Concentration of metal fume (confounder variable) was measured to control effects on antioxidant activity.

Endpoint

effects on the immune system: antioxidant activity in red blood cells and plasma

Exposure

- 50/60 Hz
- magnetic field
- occupational

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 40 h/week for 3.8 years (mean time)	electric field strength: 20 V/m minimum (at the worker's chest) electric field strength: 133 V/m maximum (at the worker's chest) magnetic flux density: 8.8 µT minimum (at the worker's chest) magnetic flux density: 84 µT maximum (at the worker's chest)

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	40 h/week for 3.8 years (mean time)

Exposure setup

Exposure source	spot welding station
Distance between exposed object and exposure source	1 m

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	20 V/m	minimum	measured	-	at the worker's chest
electric field strength	133 V/m	maximum	measured	-	at the worker's chest
magnetic flux density	8.8 µT	minimum	measured	-	at the worker's chest
magnetic flux density	84 µT	maximum	measured	-	at the worker's chest

Exposed system:

human
whole body

Methods Endpoint/measurement parameters/methodology

effects on the immune system: antioxidant activity in red blood cells (superoxide dismutase activity, glutathione peroxidase activity) and plasma (total antioxidant activity by spectrophotometry)

Investigated system:

investigation on living organism

Investigated organ system:

immune system

Time of investigation:

during exposure

Main outcome of study (acc. to author)

The mean concentration of the total antioxidant activity was higher in the exposed group than in the non-exposed group; however this difference was insignificant. In the red blood cells of the exposed group, a significant decrease in superoxide dismutase activity and glutathione peroxidase activity was observed. A significant negative correlation between magnetic field intensity and superoxide dismutase activity and glutathione peroxidase activity was observed. There was no significant correlation between metal fume exposure and antioxidant acitvity.
The findings may suggest a dose-response relationship between magnetic field strength and erythrocyte antioxidant activity, which might occur even at the recommended levels of exposure.The results indicate that extremely low frequency magnetic fields could influence the red blood cell antioxidant activity and might act as an oxidative stressor.

Study character:

medical/biological study
observational study
chronological cohort study

Study funded by

University of Tehran, Iran

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