Teratological assessment of exposure to time‐varying magnetic field

Abstract

A teratological assessment was performed using rats that were exposed to an alternating magnetic field. The magnetic field had a sawtooth waveform similar to that produced by video display terminals (VDTs). Female rats were exposed 2 weeks prior to and throughout pregnancy at a rate of 7 h/day. Three intensities of magnetic field (5.7, 23 or 66 microT) were used. All of these field intensities were much greater than those to which VDT users are exposed. A slight but statistically significant decrease in maternal lymphocyte count for the highest intensity field was found as compared with the control group. However, the lymphocyte count was within the normal range, and the observed changes in hematological parameters were considered mild. No other maternal or fetal parameters that were examined showed a significant difference for any of the three field intensities. Where minor variations in skeleton development were observed they were known to be the common "noise" that appears in every teratological evaluation.

Developmental toxicity evaluation of ELF magnetic fields in Sprague–Dawley rats

“…This interpretation was supported by the findings that MF exposure did not induce fetal ossification delay, an indication of intrauterine growth retardation, at any exposure level tested and did not cause a decrease in the body weight of male fetuses. In the developmental toxicity study of MF in rats, Stuchly et al [1988] observed a decrease in maternal lymphocyte count in the 66 mT (660 mG) exposure group, but it was within the normal range. Ryan et al [1996] found a reduction in body weight in both sexes of fetuses in the 0.2 mT (2 G) exposure group.…”

Effects of low-frequency magnetic fields on embryonic development and pregnancy.

“…In one study (38), exposure to low-frequency magnetic fields seemed to increase the number of resorptions, while slightly increased frequencies of malformations (36) or minor skeletal anomalies (39,40) were observed in other studies (table 2). Furthermore, no significant effects were found in some studies in spite of a large study sample (41,42).…”

“…A significa nt increase of minor skeletal anomalies in the highest exposure group (66 u'T) was observed when pregnant Sprague-Dawley rats were exposed to 18-kHz magnetic fields with a triangular waveform (39). The number of malformations and resorptions was low and not related to magnetic field exposure.…”

“…Only the percentage of affected fetuses was reported in the study on C3H mice (36). The proportion of affected fetuses and the proportion of affected litters were given in two studies (38,39). Only the fetusbased analysis gave significant results in the study on rats by Stuchly et al (39), while the increase of resorptions in CBA mice was significant in both analyses (38).…”

Human adverse reproductive outcomes and electromagnetic field exposures: review of epidemiologic studies.

“…Henminki and colleagues (18) (19,20,(22)(23)(24)(25)(26)(27)(28)35,36) and congenital malforiations (23,24,2627,29-33) and given less attention to other speific adverse reproductive outcomes (20,21,(26)(27)(28)32,33 (63)(64)(65)(66)(67)(68)(69). In studies where effects have been reported, the observed developmental deficits indude various congenital anomalies, developmental delay, altered sex ratio, fetal loss, reduced fertility, and demasculinization.…”