Bassen H, Litovitz T, Penafiel M, Meister R
Walter Reed Army Institute of Research, Department of Microwave Research, Washington, DC.
Bioelectromagnetics. 1992;13(3):183-98. doi: 10.1002/bem.2250130303.
Many in vitro experiments on the biological effects of extremely low frequency (ELF) electromagnetic fields utilize a uniform external magnetic flux density (B) to expose biological materials. A significant number of researchers do not measure or estimate the resulting electric field strength (E) or current density (J) in the sample medium. The magnitude and spatial distribution of the induced E field are highly dependent on the sample geometry and its relative orientation with respect to the magnetic field. We have studied the E fields induced in several of the most frequently used laboratory culture dishes and flasks under various exposure conditions. Measurements and calculations of the E field distributions in the aqueous sample volume in the containers were performed, and a set of simple, quantitative tables was developed. These tables allow a biological researcher to determine, in a straightforward fashion, the magnitudes and distributions of the electric fields that are induced in the aqueous sample when it is subjected to a uniform, sinusoidal magnetic field of known strength and frequency. In addition, we present a novel exposure technique based on a standard organ culture dish containing two circular, concentric annular rings. Exposure of the organ culture dish to a uniform magnetic field induces different average electric fields in the liquid medium in the inner and outer rings. Results of experiments with this system, which were reported in a separate paper, have shown the dominant role of the magnetically induced E field in producing specific biological effects on cells, in vitro. These results emphasize the need to report data about the induced E field in ELF in-vitro studies, involving magnetic field exposures. Our data tables on E and J in standard containers provide simple means to enable determination of these parameters.
许多关于极低频（ELF）电磁场生物效应的体外实验利用均匀的外部磁通密度（B）来暴露生物材料。相当多的研究人员没有测量或估算样品介质中产生的电场强度（E）或电流密度（J）。感应电场的大小和空间分布高度依赖于样品的几何形状及其相对于磁场的相对取向。我们研究了在各种暴露条件下，几种最常用的实验室培养皿和烧瓶中感应的电场。对容器中水性样品体积内的电场分布进行了测量和计算，并编制了一组简单的定量表格。这些表格使生物研究人员能够直接确定当水性样品受到已知强度和频率的均匀正弦磁场作用时，在其中感应的电场的大小和分布。此外，我们提出了一种基于标准器官培养皿的新颖暴露技术，该培养皿包含两个圆形同心圆环。将器官培养皿暴露于均匀磁场会在内外环的液体介质中感应出不同的平均电场。该系统的实验结果在另一篇论文中进行了报道，这些结果表明，在体外对细胞产生特定生物效应时，磁感应电场起着主导作用。这些结果强调了在涉及磁场暴露的ELF体外研究中报告感应电场数据的必要性。我们关于标准容器中E和J的数据表提供了确定这些参数的简单方法。
