Henshaw D L, Ross A N, Fews A P, Preece A W
Wills Physics Laboratory, University of Bristol, UK.
Int J Radiat Biol. 1996 Jan;69(1):25-38. doi: 10.1080/095530096146156.
We report the attraction of radon daughter nuclei in normal domestic room air to everyday sources of power frequency electromagnetic fields. TASTRAK plastic track detectors were used to measure alpha-emission from the radon (222Rn) daughters 218Po and 214Po close to 50-Hz mains frequency power cables and domestic appliance leads. We observed that wires carrying mains frequency potential attract radon daughter nuclei in a manner visually similar to the attraction of iron filings to a magnet. Increased deposition of up to a factor of 18 was observed. Further experiments designed to simulate the effect of overhead power lines at ground level showed large scale variations in local plateout and airborne concentration of radon daughters. The effects appear to be due to interactions of the electric component of the EM-field with both the ultrafine and attached fraction of radon daughter aerosols. Three mechanisms have been examined. First, aerosols instantaneously polarize in sympathy with the electric component of an applied mains frequency EM-field and as a result may migrate up strong E-field gradients. This effect is however quite weak and may only affect larger aerosols in strong field gradients. Second, charged aerosols oscillate in a 50-Hz field and in the case of the ultrafine fraction this may lead to significantly increased plateout. Third, there is the possibility that oscillation of charged aerosols induces fluctuations in the magnitude of the instantaneous charges carried and this results in a diffusive-like motion along the field lines. The effect on dose to body organs is considered. Enhanced plateout on the skin is likely, increasing the dose to the basal layer. The dose to internal organs is governed initially by inhalation and lung deposition of radon daughters. Therefore increased local concentration in room air could lead to increased dose by inhalation. E-fields are heavily attenuated by the human body and body values in tissue of no more than 10(-4) of the external field strength have been suggested. Nevertheless calculations suggest that under exposure to strong external fields this may still be sufficient to alter the deposition pattern of the charged component of the ultrafine fraction in the bronchial region. In contrast it is unlikely that internal electric fields could significantly affect the attached radon daughters. In this context the lack of measurements of residual E-fields in the cavities of the mouth, pharyngeal and bronchial regions is of considerable importance and should be addressed. We believe that the observations may have implications for the apparent enigma that there is no persuasive biological evidence to show that power frequency electromagnetic fields can influence any of the accepted stages in carcinogenesis. On the contrary, the observations show that EM-fields can concentrate in their vicinity a cocktail of radon daughter nuclei, a known carcinogen, and presumably other potentially harmful agents.
我们报告了室内正常空气中氡子体核素被日常工频电磁场源所吸引的现象。使用TASTRAK塑料径迹探测器来测量靠近50赫兹市电频率电力电缆和家用电器导线处氡（²²²Rn）子体²¹⁸Po和²¹⁴Po的α发射。我们观察到，携带工频电势的导线吸引氡子体核素的方式在视觉上类似于铁屑被磁铁吸引。观察到沉积量增加达18倍。进一步设计用于模拟地面架空电力线影响的实验表明，氡子体的局部沉降和空气中浓度存在大规模变化。这些影响似乎是由于电磁场的电场分量与氡子体气溶胶的超细部分和附着部分相互作用所致。已研究了三种机制。首先，气溶胶会随着外加工频电磁场的电场分量瞬间极化，结果可能会沿强电场梯度向上迁移。然而，这种效应相当微弱，可能仅在强场梯度中影响较大的气溶胶。其次，带电气溶胶在50赫兹场中振荡，对于超细部分而言，这可能会导致沉降显著增加。第三，存在带电气溶胶振荡会引起所携带的瞬间电荷量大小波动的可能性，这会导致沿场线产生类似扩散的运动。考虑了对人体器官剂量的影响。皮肤表面沉降增强很可能会增加基底层的剂量。内部器官的剂量最初由氡子体的吸入和肺部沉积决定。因此，室内空气中局部浓度增加可能会导致吸入剂量增加。电场会被人体大幅衰减，有人提出人体组织中的场强值不超过外部场强的10⁻⁴。然而，计算表明，在暴露于强外部场的情况下，这仍可能足以改变超细部分带电成分在支气管区域的沉积模式。相比之下，内部电场不太可能显著影响附着的氡子体。在此背景下，口腔、咽部和支气管区域腔内残余电场缺乏测量具有相当重要的意义，应予以关注。我们认为，这些观察结果可能对一个明显的谜团具有启示意义，即没有确凿的生物学证据表明工频电磁场会影响癌症发生的任何公认阶段。相反，这些观察结果表明，电磁场能够在其附近聚集已知致癌物氡子体核素的混合物以及大概其他潜在有害物质。
