Acute and subchronic toxicity of 20kHz and 60kHz magnetic fields in rats

• Published in: Journal of applied toxicology 2016-02, Vol.36 (2), p.199-210
• Main Authors: Nishimura, Izumi, Oshima, Atsushi, Shibuya, Kazumoto, Mitani, Takashi, Negishi, Tadashi
• Format: Article
• Language: English
• Subjects: Exposure; Health; Hematology; Histopathology; Intermediate frequency; Magnetic fields; Organ weight; Rats; Rodents; Toxicity
• ISSN: 0260-437X; 1099-1263
• DOI: 10.1002/jat.3161

Despite increasing use of intermediate frequency (IF) magnetic fields (MFs) in occupational and domestic settings, scientific evidence necessary for health risk assessments of IF MF is insufficient. Male and female Crl:CD(SD) rats (12 per sex per group) were exposed to 20kHz, 0.20 mT(root mean square, rms) or 60kHz, 0.10mT(rms) sinusoidal MFs for 22hday super(-1) for 14days (acute) or 13weeks (subchronic). Experiments were duplicated for each frequency to ensure outcome reproducibility, and examinations were blinded for quality assurance. All rats survived without significant clinical signs until the end of experiments. Some changes in body weight between the MF-exposed and control groups were observed over the course of exposure, although the directions of the changes were inconsistent and not statistically significant after subchronic exposure. There were significant differences between MF-exposed and control groups in some organ weights and parameters in hematology and clinical chemistry, but these were minor in magnitude and not repeated in duplicate experiments. Histopathological findings reflecting toxicity were sporadic. Frequencies of other findings were similar to historic data in this rat strain, and findings had no specific relationship to changes in organ weight or parameters of hematology and clinical chemistry in each animal. The changes observed throughout this study were considered biologically isolated and were attributable to chance associations rather than to MF exposure. The results, in particular the histopathological evidence, indicate an absence of toxicity in IF MF-exposed rats and do not support the hypothesis that IF MF exposure produces significant toxicity. Despite increasing use of intermediate frequency (IF) magnetic fields (MFs) in occupational and domestic settings, scientific evidence is insufficient for IF MF health risk assessments. Rats were exposed to 20kHz or 60kHz sinusoidal MFs for 22hday super(-1) for 14days (acute) or 13weeks (subchronic). MF-exposed rats did not exhibit significant and reproducible changes in body and organ weights, hematology, clinical chemistry and histopathology. Our results indicate that IF MF exposure does not carry a significant health risk to mammals.