Department of Psychological Medicine, Institute of Psychiatry, King’s College London, London, UK.
Occup Environ Med. 2011 May;68(5):339-44. doi: 10.1136/oem.2010.055889. Epub 2010 Sep 23.
Concerns have been raised about possible health effects from radiofrequency fields pulsing at around 16 Hz. A radio system used by UK police (TETRA) employs signals which pulse at 17.6 Hz. We tested whether exposure to a continuous wave signal at 385.25 MHz or a TETRA-like signal resulted in symptoms among users reporting sensitivity to TETRA compared to users not reporting sensitivity to TETRA.
60 sensitive and 60 non-sensitive users were exposed to three 50 min conditions: a signal with a 16 Hz component, a continuous wave condition and a sham condition. The mean radiated power for the 16 Hz and continuous wave conditions was 250 mW. The order of conditions was randomised and testing was conducted double-blind. Participants reported the severity of eight symptoms during and after each exposure, their mood state at the end of each exposure, and whether they could tell which sessions involved active signals. The study was registered in advance with the ISRCTN register.
Exposure to the continuous wave signal increased ratings of headache in all participants, fatigue in non-sensitive participants and difficulty concentrating in sensitive participants. Paradoxically, it reduced sensations of itching in sensitive participants. These effects were not observed in the condition with 16 Hz pulsing, except for those relating to concentration. Adjusting for multiple comparisons removed most significant effects, but not those relating to itch.
The results suggested that exposure to TETRA signals is not responsible for symptoms reported by some users, although exposure to a continuous wave signal may affect symptoms. Clinical trial number ISRCTN 73321766.
人们对频率约为 16Hz 的射频场脉冲可能产生的健康影响表示担忧。英国警方使用的一种无线电系统（TETRA）采用的信号以 17.6Hz 的频率脉冲。我们测试了连续波信号在 385.25MHz 或 TETRA 样信号下是否会导致报告对 TETRA 敏感的用户出现症状，而不是报告对 TETRA 不敏感的用户出现症状。
60 名敏感和 60 名非敏感用户暴露于三种 50 分钟的条件下：具有 16Hz 分量的信号、连续波条件和假条件。16Hz 和连续波条件的平均辐射功率为 250mW。条件的顺序是随机的，测试是双盲进行的。参与者在每次暴露期间和之后报告了八种症状的严重程度、每次暴露结束时的情绪状态，以及他们是否能够判断哪些阶段涉及活动信号。该研究已提前在 ISRCTN 登记处登记。
连续波信号的暴露增加了所有参与者的头痛评分、非敏感参与者的疲劳感和敏感参与者的注意力集中困难。矛盾的是，它减轻了敏感参与者的瘙痒感。除了与注意力集中有关的症状外，在 16Hz 脉冲条件下没有观察到这些效应。调整多重比较后，大多数显著效应消失，但与瘙痒有关的效应没有消失。
结果表明，TETRA 信号的暴露并不是一些用户报告的症状的原因，尽管暴露于连续波信号可能会影响症状。临床试验编号 ISRCTN 73321766。
