Long-term exposure of Sprague Dawley rats to 20 kHz triangular magnetic fields.
OBJECTIVE
There are only a few reports on harmful effects of 20 kHz sine waves; however, it is essential to comprehensively evaluate the potentially harmful effect of triangular signals at the same frequency. Therefore, in this study, effects of long-term exposure to 20 kHz magnetic fields was examined.


METHODS
Eighty Sprague Dawley rats were divided into two groups (half male and female in each sham and exposed groups), and they were exposed to 20 kHz triangular magnetic fields at 6.25 microT rms for 8 h/day for 12 or 18 months. Urinalysis [pH, glucose, protein, ketone bodies, red blood cells (RBC), nitrogen, bilirubin, urobilinogen, and specific gravity], hematological analysis (RBC, hemoglobin, hematocrit, thrombocyte count, and leucocyte count), blood biochemistry (total protein, blood urea nitrogen, creatinine, glucose, total bilirubin, total cholesterol, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase), and histopathological analysis of organs (thymus, stomach, intestine, liver, kidney, testis, ovary, spleen, brain, heart, and lung) were performed.


RESULTS
No significant differences were seen between 20 kHz magnetic-fields exposed rats and sham-exposed rats in body and organ weights, hematological analysis, blood biochemistry, urinalysis data, and histopathological examination, except for the numbers of neutrophiles and lymphocytes in female rats. The number of neutrophiles was significantly increased in female rats on the 12th month after exposure, and the number of lymphocytes in female rats was significantly decreased on the 18th month.


CONCLUSIONS
Long-term exposure of rats to 20 kHz triangular magnetic fields did not induce any significantly harmful effects, except changes in neutrophiles at 12 months and lymphocytes at 18 months of exposure in female rats. These hematological changes need to be investigated again at a higher intensity of 20 kHz magnetic fields.
Lee
H J
HJ
Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
Kim
S H
SH
Choi
S Y
SY
Gimm
Y M
YM
Pack
J K
JK
Choi
H D
HD
Lee
Y S
YS
D000818:Animals; D001773:Blood Cells / Q000473:pathology / Q000528:radiation effects*; D001798:Blood Proteins / Q000032:analysis*; D001822:Body Burden; D001835:Body Weight / Q000528:radiation effects*; D004574:Electromagnetic Fields / Q000009:adverse effects*; D005260:Female; D008297:Male; D009929:Organ Size / Q000528:radiation effects*; D009928:Organ Specificity; D011829:Radiation Dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D018570:Risk Assessment; D012307:Risk Factors; D014781:Viscera / Q000473:pathology / Q000528:radiation effects; D014916:Whole-Body Irradiation / Q000009:adverse effects*
D001798:Blood Proteins