Developmental toxicity study of 60 Hz (power frequency) magnetic fields in rats

Abstract

Considerable public concern has developed regarding possible adverse reproductive outcomes resulting from exposure to power frequency magnetic fields (MF). To identify possible effects of MF exposure on fetal development, timed‐pregnant female Sprague‐Dawley rats (55/group) received continuous exposure to linearly polarized, transient‐free 60 Hz MF at field strengths of 0 Gauss (G; sham control), 0.02 G, 2 G, or 10 G, or intermittent (1 hr on/1 hr off) exposure to 10 G fields. Dams received MF or sham exposures for 18.5 hr/day on gestation days 6 through 19. A positive control group of 15 dams received daily oral doses of 85 mg ethylenethiourea (ETU)/kg body weight on gestation days 11, 12, and 13; positive control dams received no MF exposure. Ambient and experimentally generated MF were monitored continuously throughout the study. Experimentally generated MF were within 2% of the target field strengths at all times, and ambient MF to which sham controls were exposed did not exceed 0.7 mG at any point in the study. No evidence of maternal toxicity was identified in any MF‐exposed dam; mean maternal body weight and organ weights in groups exposed to MF did not differ from those in sham controls. Comparisons of fetal viability and body weight demonstrated no biologically significant differences between MF‐exposed groups and sham controls. Similarly, a battery of gross external, visceral, skeletal, and cephalic examinations demonstrated no significant differences in the incidence of fetal malformations or anomalies in MF‐exposed groups vs. sham controls. By contrast, 100% of the fetuses in the positive control group treated with ETU demonstrated malformations and reduced body weight. Exposure of pregnant Sprague‐Dawley rats to 60 Hz at field strengths up to 10 G during gestation days 6–19 did not produce biologically significant effects in either dams or fetuses. These results do not support the hypothesis that exposure to pure, linearly polarized 60 Hz MF is a significant risk factor for the developing fetus. © 1996 Wiley‐Liss, Inc.

Differential effects of high and low strength magnetic fields on mouse embryonic development and vasculogenesis of embryonic stem cells

“…In consistence with our results a decreased weight and a decreased size of fetuses was previously described if MF exposure started early during pregnancy [70,87,88]. Interestingly, some other studies showed no significant differences of the weight and length of fetuses if MFs were applied [90][91][92][93]. In the present study embryos at day 5 and 8 of pregnancy showed a normal growth while the vitality of the embryos was affected after exposure to 10 mT MFs.…”

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in F344/N Rats

“…We have previously reported the results of subchronic toxicity studies in rats and mice (7), a developmental toxicology study in rats (44), and a battery of immunotoxicology studies in mice and rats (26); all studies were considered negative for evidence of toxicity. Studies of the influence of magnetic fields on lymphoma induction in 2 strains of transgenic mice were also negative for an effect on lymphoma induction (31), as were the results of a multigeneration reproductive toxicity evaluation in rats (37,45 Tissues were excised, fixed in 10% neutral-buffered formalin, embedded in paraffin, cut, stained with hematoxylin and eosin, and evaluated using methods defined in NTP pathology specifications. All gross lesions and approximately 45 additional tissues from all animals in all study groups were examined histopathologically.…”

“…Studies of the influence of magnetic fields on lymphoma induction in 2 strains of transgenic mice were also negative for an effect on lymphoma induction (31), as were the results of a multigeneration reproductive toxicity evaluation in rats (37,45 Tissues were excised, fixed in 10% neutral-buffered formalin, embedded in paraffin, cut, stained with hematoxylin and eosin, and evaluated using methods defined in NTP pathology specifications. All gross lesions and approximately 45 additional tissues from all animals in all study groups were examined histopathologically. All tumors diagnosed in the study were reviewed by a quality assurance pathologist.…”

Chronic Toxicity/Oncogenicity Evaluation of 60 Hz (Power Frequency) Magnetic Fields in B6C3F1 Mice

“…When considered together, the results of these studies neither support nor dispute the hypothesis that exposure to EMFs is a significant risk factor for human cancer. Recently published studies have generated both positive and negative results, and therefore provide no conclusive data set on which potential human risks can be assessed (11,30,31,36 (14), and a multigeneration reproductive toxicity evaluation in rats (22,29); all studies were essentially negative. Studies in 2 strains of transgenic mice that demonstrate a genetic predisposition to hematopoietic neoplasia also failed to demonstrate any increases in lymphoma incidence in EMF-exposed mice (19 (Fig.…”