Lack of teratological effects in rats exposed to 20 or 60 kHz magnetic fields

Abstract

BACKGROUND: A risk assessment of magnetic field (MF) exposure conducted by the World Health Organization indicated the need for biological studies on primary hazard identification and quantitative risk evaluation of intermediate frequency (300 Hz–100 kHz) MFs. Because induction heating cookers generate such MFs for cooking, reproductive and developmental effects are a concern due to the close proximity of the fields' source to a cook's abdomen. METHODS: Pregnant Crl:CD(SD) rats (25/group) were exposed to a 20 kHz, 0.2 mT(rms) or 60 kHz, 0.1 mT(rms) sinusoidal MF or sham-exposed for 22 hr/day during organogenesis, and their fetuses were examined for malformations on gestation day 20. All teratological evaluations were conducted in a blind fashion, and experiments were duplicated for each frequency to confirm consistency of experimental outcomes. RESULTS: No exposure-related changes were found in clinical signs, gross pathology, or number of implantation losses. The number of live fetuses and low-body-weight fetuses as well as the incidence of external, visceral, and skeletal malformations in the fetuses did not indicate significant differences between MF-exposed and sham-exposed groups. Although some fetuses showed isolated changes in sex ratio and skeletal variation and ossification, such changes were neither reproduced in duplicate experiments nor were they common to specific field frequencies. CONCLUSIONS: Exposure of rats to MFs during organogenesis did not show significant reproducible teratogenicity under experimental conditions. Present findings do not support the hypothesis that intermediate frequency MF exposure after implantation carries a significant risk for developing mammalian fetuses. Birth Defects Res (Part B) 92:469–477, 2011. © 2011 Wiley Periodicals, Inc.

The Effect of Electromagnetic Fields with the Mg<sup>2+</sup> Cyclotron Frequency on Mouse Reproductive Performance

“…Consistent with reports in the literature, the observed changes were sporadic and did not affect organogenesis in the offspring [17]- [22]. Table 2.…”

Absence of reproductive and developmental toxicity in rats following exposure to a 20-kHz or 60-kHz magnetic field

“…The MF exposure facility was explicitly described in a previous paper that also included a photograph (Nishimura et al, 2011). A pair of exposure facilities, one for 20 kHz and another for 60 kHz, were built in an area where the background 50 Hz MF was extremely low at <0.02 lT(rms).…”

“…In another previous study in rodents (Nishimura et al, 2011), we exposed pregnant rats to IF MFs at 20 kHz in 0.2 mT(rms) and at 60 kHz in 0.1 mT(rms) during organogenesis for teratological evaluation. The present study in rats was performed in conjunction with the rat teratology study to cover an exposure period from pre-mating to implantation.…”

Impact of electromagnetic radiation exposure during pregnancy on embryonic skeletal development in rats

“…Nishimura et al [27] found that exposure to intermediate frequency (300 Hz-100 KHz) magnetic fields during embryogenesis showed no teratogenic effect under experimental conditions. Foci of ossification when starting configuration in the normal bone development, the chondrocytes become enlarged and their cytoplasm vacuolated.…”