Hansson H A
Institute of Neurobiology, University of Gothenburg, Sweden.
Prog Clin Biol Res. 1988;257:119-34.
Exposure to electromagnetic fields may cause various types of effects on nervous tissue, in severe cases even irreversible damage. The exposure conditions, i.e. frequency including type and extent of modulation, time, intensity, wave form, as well as shape, size and position of exposed subject and possible treatment with drugs, are factors determining if damage, acute or chronic, ultimately result. Long term exposure of newborn rabbits, rats and mice to electromagnetic fields of power frequency (10-14 kV/m; 50 or 60 Hz; sinusoidal wave form; 21-24 h per day) may cause affection and even damage to the nervous system. Large nerve cells showed reactive changes such as lamellar bodies and cytoskeletal alteration to an extent varying with exposure conditions. Reactive neuroglial changes as well as increase in neuroglial marker proteins could concomitantly be demonstrated. The changes seemed to be reversible although we only have incomplete data available. Exposure in vitro of frog sciatic nerve to 16-60 Hz sinusoidal low current (50-1000 nA) for 17 h induced cytoskeletal changes. Exposure of rabbits to pulsed microwaves of moderate to high intensity (3.1 GHz; 300 Hz modulation; peak duration 1.4 usec with maximal peak intensity about 1000 times average; 55 mW/cm; SAR in the brain cortex about 20 W/kg; increase of temperature as measured by lightguide-equipped instruments in right brain hemisphere about 1-2 degrees C) during 1 h per day during three days resulted in no obvious initial changes in behaviour. Minimal acute dam- age could be demonstrated. However, after two to four months and later on both structural, immunohistochemical and biochemical changes could be documented. Radar technicians accidently and/or occupationally exposed to microwaves showed psychoneurological signs of affection as well as changes in cerebrospinal fluid protein pattern. No related changes have been noticed among matched controls. Exposure of nervous tissue to electromagnetic fields ranging from power frequency to microwaves may thus exert a wide range of effects, mostly by mechanisms we know little about.
暴露于电磁场可能会对神经组织产生各种影响，在严重情况下甚至会造成不可逆转的损害。暴露条件，即频率（包括调制类型和程度）、时间、强度、波形，以及暴露对象的形状、大小和位置，还有可能的药物治疗，都是决定最终是否会造成急性或慢性损害的因素。新生兔、大鼠和小鼠长期暴露于工频电磁场（10 - 14 kV/m；50或60 Hz；正弦波形；每天21 - 24小时）可能会导致神经系统受到影响甚至损害。大型神经细胞表现出反应性变化，如板层小体和细胞骨架改变，其程度随暴露条件而变化。同时可证明有反应性神经胶质细胞变化以及神经胶质标记蛋白增加。尽管我们只有不完整的数据，但这些变化似乎是可逆的。青蛙坐骨神经在体外暴露于16 - 60 Hz正弦低电流（50 - 1000 nA）17小时会诱导细胞骨架变化。兔子每天暴露于中高强度脉冲微波（3.1 GHz；300 Hz调制；峰值持续时间1.4微秒，最大峰值强度约为平均值的1000倍；55 mW/cm；大脑皮层比吸收率约为20 W/kg；配备光导仪器测量的右脑半球温度升高约1 - 2摄氏度），持续三天，每天1小时，行为上最初没有明显变化。可证明有最小程度的急性损害。然而，在两到四个月后及更晚些时候，结构、免疫组织化学和生化变化都有记录。意外和/或职业性暴露于微波的雷达技术人员表现出精神神经方面的受影响迹象以及脑脊液蛋白模式的变化。在匹配的对照组中未发现相关变化。因此，神经组织暴露于从工频到微波的电磁场可能会产生广泛的影响，其作用机制大多我们还知之甚少。
