Medical/biological study (experimental study)

Chronic exposure of Sprague-Dawley rats to 20 kHz triangular magnetic fields med./bio.

By: Lee HJ, Gimm YM, Choi HD, Kim N, Kim SH, Lee YS

Published in: Int J Radiat Biol 2010; 86 (5): 384-389

This study was conducted to investigate the effects of long-term exposure (18 months) to 20 kHz intermediate frequency magnetic fields on different physiological parameters in rats.

80 rats were divided into four groups (male and female separately, two sham exposed and two exposed groups). The applied magnetic flux density of 30 µT represents the exposure limit value for the occupational exposure of 20 kHz magnetic fields in Korea (in contrast to the applied magnetic flux density of a previous study (Lee et al. 2006) representing the exposure limit for the general population (6.25 µT)).

effects on body weight, organ weight and morphology, urine analysis, hematological and blood biochemistry analyses, morbidity and mortality

Exposure	Parameters
Exposure 1: 20 kHz Exposure duration: continuous for 8 hr/day, 5 days/week over 18 months	magnetic flux density: 30 µT effective value (at the center of the top panel) magnetic flux density: 31.09 µT effective value (+/- 1.16 µT at the top panel) magnetic flux density: 30.73 µT effective value (+/- 0.46 µT at the bottom panel) magnetic flux density: 0.11 µT (60 Hz component)

Frequency	20 kHz
Type	magnetic field
Exposure duration	continuous for 8 hr/day, 5 days/week over 18 months
Additional info	triangular waves

Exposure source	coil(s)
Setup	420 cm x 260 cm x 180 cm polycarbonate cages
Sham exposure	A sham exposure was conducted.

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	30 µT	effective value	measured	-	at the center of the top panel
magnetic flux density	31.09 µT	effective value	measured	-	+/- 1.16 µT at the top panel
magnetic flux density	30.73 µT	effective value	measured	-	+/- 0.46 µT at the bottom panel
magnetic flux density	0.11 µT	-	measured	-	60 Hz component

Exposed system:

Investigated system:

Investigated organ system:

Time of investigation:

The data showed that exposure of rats to a 20 kHz intermediate frequency magnetic field with 30 µT flux density for 18 months did not induce any abnormalities in organ weights and did not induce any significant changes in hematological factors, blood biochemistry, urological factors, and histopathological findings. Total tumour incidence was not different between sham-exposed and magnetic field-exposed animals.

Study character:

Lotfi A et al. (2011): Effects of exposure to constant or pulsed 50 Hz magnetic fields on body weight and blood glucose concentration of BALB/C mice
Lee HJ et al. (2009): Teratological evaluation of mouse fetuses exposed to a 20 kHz EMF
Contalbrigo L et al. (2009): Effects of different electromagnetic fields on circadian rhythms of some haematochemical parameters in rats
Lee HJ et al. (2007): Lack of promotion of mammary, lung and skin tumorigenesis by 20 kHz triangular magnetic fields
Kim SH et al. (2006): Toxicity bioassay in Sprague-Dawley rats exposed to 20 kHz triangular magnetic field for 90 days
Lee HJ et al. (2006): Long-term exposure of Sprague Dawley rats to 20 kHz triangular magnetic fields
Kim SH et al. (2004): Teratological studies of prenatal exposure of mice to a 20 kHz sawtooth magnetic field
Kurokawa Y et al. (2004): Evaluation of residential exposure to intermediate frequency magnetic fields
Svedenstal BM et al. (1998): Effects of exposure to 50 Hz or 20 kHz magnetic fields on weights of body and some organs of CBA mice
Svedenstal BM et al. (1998): Leukocytes and micronucleated erythrocytes in peripheral blood from mice exposed to 50 Hz or 20 kHz magnetic fields
Ubeda A et al. (1997): Hematological changes in rats exposed to weak electromagnetic fields