Conover D L, Moss C E, Murray W E, Edwards R M, Cox C, Grajewski B, Werren D M, Smith J M
Physical Agents Effects Branch, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998.
Bioelectromagnetics. 1992;13(2):103-10. doi: 10.1002/bem.2250130204.
Data are presented on ankle-specific SARs and foot currents as a function of strengths of radio-frequency electromagnetic fields encountered by operators of dielectric heaters. The determination of foot currents was based on near-field exposures in which reactive coupling dominates, and which can result in substantial SARs in exposed workers. The operators were located less than one wavelength from--usually within one meter of--the dielectric heaters, which generated fields at frequencies from 6.5 to 65 MHz. At distances normally assumed by workers, maximal strengths of electric fields ranged from 10(4) to 2.4 x 10(6) V2/m2; maximal strengths of magnetic fields ranged from 5.0 x 10(-3) to 33.3 A2/m2. Currents through both feet to ground were measured while operators stood where they normally worked. Maximal currents ranged from 3 to 617 mA, rms. Nearly 27 percent of the dielectric heaters induced foot currents that exceeded the 200-mA limit that has been proposed for a new ANSI C95.1 standard. Twenty percent of the heaters induced foot currents that exceeded 350 mA. SARs in ankles were calculated from foot currents, and they approximated 5 W/kg at 100 mA, 29 W/kg at 250 mA, and 57 W/kg at 350 mA. The maximal SAR in the ankle was approximately 176 W/kg at 617 mA.
本文给出了踝关节特定比吸收率（SAR）和足部电流的数据，这些数据是介电加热器操作人员所接触的射频电磁场强度的函数。足部电流的测定基于近场暴露情况，在这种情况下，无功耦合起主导作用，并且可能导致暴露工人出现大量的比吸收率。操作人员距离介电加热器不到一个波长——通常在一米以内——介电加热器产生的场频率范围为6.5至65兆赫兹。在工人通常所处的距离处，电场的最大强度范围为10⁴至2.4×10⁶伏²/米²；磁场的最大强度范围为5.0×10⁻³至33.3安²/米²。当操作人员站在他们正常工作的位置时，测量了通过双脚流向地面的电流。均方根最大电流范围为3至617毫安。近27%的介电加热器会感应出超过为新的美国国家标准学会（ANSI）C95.1标准所提议的200毫安限值的足部电流。20%的加热器会感应出超过350毫安的足部电流。根据足部电流计算出踝关节处的比吸收率，在100毫安时约为5瓦/千克，在250毫安时约为29瓦/千克，在350毫安时约为57瓦/千克。在617毫安时，踝关节处的最大比吸收率约为176瓦/千克。
