Ryan B M, Polen M, Gauger J R, Mallett E, Kearns M B, Bryan T L, McCormick D L
Life Sciences Department, IIT Research Institute, 10 West 35th Street, Chicago, Illinois 60616, USA.
Radiat Res. 2000 May;153(5 Pt 2):637-41. doi: 10.1667/0033-7587(2000)153[0637:eotdto]2.0.co;2.
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.
实验数据表明，暴露于工频磁场（MFs）的50和60赫兹正弦波成分对胎儿发育没有不利影响。然而，MF谐波可能的发育毒性尚未得到研究。本研究旨在确定单独暴露于180赫兹MFs或与60赫兹MFs联合暴露是否会在斯普拉格-道利大鼠中诱发出生缺陷。将精子阳性的母鼠分组（每组≥20只），从妊娠第6天至第19天，每天暴露18.5小时于以下环境：（1）仅暴露于环境磁场（<0.0001毫特斯拉；假对照组）；（2）0.2毫特斯拉的60赫兹MFs；（3）0.2毫特斯拉的180赫兹MFs；或（4）60赫兹+180赫兹MFs（10%三次谐波；总场强=0.2毫特斯拉）。测定每只母鼠的窝仔数、窝仔体重、活产百分比、性别比和吸收部位数量，并对所有胎儿进行大体外观、内脏、头部和骨骼检查。MF暴露对窝仔数、窝仔体重或胎儿发育没有显著影响。除了常见的肋骨变异外，所有组胎儿异常的发生率相当。在暴露于60赫兹+180赫兹MFs的组中，肋骨变异的发生率略有增加；然而，该组肋骨变异的发生率与我们实验室历史对照组的发生率相似。这些数据通过证明单独暴露于180赫兹MFs或叠加在60赫兹基础信号上的暴露不会诱发具有生物学意义的发育毒性，扩展了关于MFs发育毒性的现有数据库。这些数据不支持暴露于工频MFs是胎儿发育重要风险因素的假设。
