Evaluation of the Developmental Toxicity of 60 Hz Magnetic Fields and Harmonic Frequencies in Sprague-Dawley Rats

Abstract

Experimental data suggest that exposure to the 50 and 60 Hz sinusoidal components of power-frequency magnetic fields (MFs) does not have an adverse impact on fetal development. However, the possible developmental toxicity of MF harmonics has not been investigated. This study was designed to determine whether exposure to 180 Hz MFs (third harmonic), alone or in combination with 60 Hz MFs, induces birth defects in Sprague-Dawley rats. Groups of sperm-positive dams (> or =20/group) were exposed for 18.5 h per day from gestation days 6 through 19 to (1) ambient MFs only (<0.0001 mT; sham controls); (2) 60 Hz MFs at 0.2 mT; (3) 180 Hz MFs at 0.2 mT; or (4) 60 Hz + 180 Hz MFs (10% third harmonic; total field strength = 0.2 mT). Litter size, litter weight, percentage live births, sex ratio, and number of resorption sites were determined for each dam, and gross external, visceral, cephalic and skeletal examinations were performed on all fetuses. MF exposure had no significant effects on litter size, litter weight, or fetal development. With the exception of common rib variants, the incidence of fetal anomalies was comparable in all groups. A small increase in the incidence of rib variants was seen in the group exposed to 60 Hz + 180 Hz MFs; however, the incidence of rib variants in this group was similar to that in historical controls from our laboratory. These data extend the existing database on developmental toxicity of MFs by demonstrating that exposure to 180 Hz MFs, either alone or superimposed on an underlying 60 Hz signal, does not induce biologically significant developmental toxicity. These data do not support the hypothesis that exposure to power-frequency MFs is an important risk factor for fetal development.

The Effect of Electromagnetic Fields with the Mg&lt;sup&gt;2+&lt;/sup&gt; Cyclotron Frequency on Mouse Reproductive Performance

“…With respect to the birth rate data, the ELF-EMF exposure elicited a mild effect, which was limited to a significant reduction of the offspring number per birth; although the total offspring during the entire period of the trial did not change. In agreement with the literature [15]- [18], EMF exposure did not cause adverse effects on reproductive performance.…”

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

“…They observed increased minor variations in skeletal development but interpreted them as commonly observed changes that appear in every teratological evaluation. Ryan et al (2000) exposed SD pregnant rats from gestation days 6 to 19 to 60 Hz and/or its third harmonic 180 Hz MFs. They also found increased rib variants in the 60 Hz and superimposed 180 Hz MFs group, but the frequency of the variants was similar to that in a historical control from their laboratory.…”

Extremely Low Frequency Magnetic Fields Induce Spermatogenic Germ Cell Apoptosis: Possible Mechanism

“…There is some consistency in increase of minor skeleton alterations in several experiments [26, 27, 31–33]. The skeletal variation may result from statistical fluctuation and is often considered biologically insignificant [34].…”