Tahvanainen Kari, Niño Juanita, Halonen Pirjo, Kuusela Tom, Alanko Tommi, Laitinen Tomi, Länsimies Esko, Hietanen Maila, Lindholm Harri
New Technologies and Risks, Finnish Institute of Occupational Health, Helsinki, Finland.
Clin Physiol Funct Imaging. 2007 May;27(3):162-72. doi: 10.1111/j.1475-097X.2007.00730.x.
The earlier studies using phantom models and human subjects concerning warming effects during cellular phone use have been controversial, partly because radiofrequency (RF) exposures have been variable. In this randomized, double-blind, placebo-controlled crossover trial, 30 healthy subjects were submitted to 900 MHz (2W) and 1800 MHz (1W) cellular phone RF exposure, and to sham exposure in separate study sessions. Temperature signals were recorded continuously in both ear canals before, during and after the 35-min RF exposure and the 35-min sham exposure sessions. Temperature was measured by using small-sized NTC thermistors placed in the ear canals through disposable ear plugs. The mean temperature changes were determined during a set cardiovascular autonomic function studies: during a 5-min controlled breathing test, during a 5-min spontaneous breathing test, during 7-min head-up tilting, 1-min before, during and after two consecutive Valsalva manoeuvres and during a deep breathing test. Temperatures in the exposed ear were significantly higher during RF exposures compared with sham exposure in both 900 and 1800 MHz studies with maximum differences of 1 x 2 +/- 0 x 5 degrees C (900 MHz exposure) and 1 x 3 +/- 0 x 7 degrees C (1800 MHz exposure). Temperatures in the RF-exposed ear were also significantly higher during the postexposure period compared with post-sham exposure period with maximum differences of 0 x 6 +/- 0 x 3 degrees C for 900 MHz and 0 x 5 +/- 0 x 5 degrees C for 1800 MHz. The results of this study suggest that RF exposure to a cellular phone, either using 900 or 1800 MHz with their maximal allowed antenna powers, increases the temperature in the ear canal. The reason for the ear canal temperature rising is a consequence of mobile phone battery warming during maximal antenna power use. The earlier published articles do not indicate that temperature rising in the ear canal has any significant contribution from the RF fields emitted from mobile phones.
早期使用人体模型和人体受试者进行的关于手机使用时热效应的研究一直存在争议，部分原因是射频（RF）暴露情况各不相同。在这项随机、双盲、安慰剂对照的交叉试验中，30名健康受试者分别在不同的研究阶段接受了900兆赫（2瓦）和1800兆赫（1瓦）的手机射频暴露以及假暴露。在35分钟的射频暴露和35分钟的假暴露期间及前后，连续记录双耳耳道的温度信号。通过一次性耳塞将小型NTC热敏电阻置于耳道中来测量温度。在一系列心血管自主功能研究中确定平均温度变化：在5分钟的控制呼吸测试期间、5分钟的自主呼吸测试期间、7分钟的头高位倾斜期间、连续两次瓦尔萨尔瓦动作前1分钟、动作期间和动作后以及深呼吸测试期间。在900兆赫和1800兆赫的研究中，与假暴露相比，射频暴露期间暴露耳的温度显著更高，最大差异分别为1.2±0.5摄氏度（900兆赫暴露）和1.3±0.7摄氏度（1800兆赫暴露）。与假暴露后阶段相比，暴露后阶段暴露耳的温度也显著更高，900兆赫时最大差异为0.6±0.3摄氏度，1800兆赫时为0.5±0.5摄氏度。本研究结果表明，使用900兆赫或1800兆赫且天线功率达到最大允许值的手机进行射频暴露会使耳道温度升高。耳道温度升高的原因是在天线最大功率使用期间手机电池发热。早期发表的文章并未表明耳道温度升高有来自手机发射的射频场的任何显著贡献。
