80 three-week-old rats were used (half male and female in each sham exposed and exposed groups). The applied magnetic flux density of 6.25 µT represents the exposure limit for the public of 20 kHz magnetic fields in Korea.
Male and females were equally divided into 2 groups for sham and active exposures.
The body weight was significantly reduced in both male and female rats of the 18 months exposure group. Blood examinations revealed significantly increased number of neutrophils after 12 months exposure, and significantly decreased number of lymphocytes in the 18 months exposure group, but only in female rats. Other investigated parameters were unaffected.
In conclusion, these results indicate that long-term exposure of rats to 20 kHz magnetic fields do not induce any significantly harmful effects, except changes in neutrophils and lymphocytes in female rats. These hematological changes need to be further investigated.