Zhao Jing, Sun Jianjun, Jia Zhonghong
Chinese PLA Postgraduate Medical School, General Hospital of Chinese PLA, Beijing, 100853, China.
Lin Chuang Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2013 May;27(9):471-4.
Our purpose was to investigate occupational high-strength very low frequency electric and magnetic fields (VLF EMFs) and assess changes of function of the inner ear.
The people exposed to high-strength VLF EMFs were divided into three groups: long- term exposure group ( > 5 years), short-term exposure group (< 5 years) and the control group. The field intensity indicator and noise analyzer were employed for the examination of the electromagnetic energy intensity and noise value at the working sites. Self-administered questionnaire was adopted. Universal hearing screening by pure tone audiometry (PTA) and distortion product otoacoustic emission (DPOAE) were done. The subjects who failed the screening tests were confirmed with auditory brainstem response (ABR) test.
The frequency of the electromagnetic field was 20 kHz, the average electric power density in job locations was 21-38 kV/m, which was higher than national standard (< 5 kV/m). Average noise-level in job locations was 52-65 dBHL, which was within the standard. Questionnaire presented that VLF EMFs might increase the incidence of headache, insomnia and tinnitus in long-term exposure. The incidence of abnormal DPOAE was higher in the subjects of the long-term exposure group than the short-term exposure group and the control group (P < 0.01). At 676, 933, 3616, 5130, 7253 Hz, the DPOAE amplitudes of the long term exposure group workers were significantly lower than the short-term exposure group and the control group. There was no obvious difference of the incidence of abnormal DPOAE between the short-term exposure group and the control group. The result of ABR with those subjects with abnormal DPOAE were no significant abnormalities.
The average electric power density in job locations was significant worse than health standards. The changes of DPOAE indicated that the exposure to high-strength VLF EMFs had a subtle, discreet and localized impairing effect on outer hair cells. Effective intervention measures should be taken.
本研究旨在调查职业性高强度极低频电磁场（VLF EMFs）并评估内耳功能变化。
将暴露于高强度VLF EMFs的人员分为三组：长期暴露组（>5年）、短期暴露组（<5年）和对照组。使用场强仪和噪声分析仪检测工作场所的电磁能量强度和噪声值。采用自填式问卷。通过纯音听力计（PTA）和畸变产物耳声发射（DPOAE）进行普遍听力筛查。对筛查测试不合格的受试者进行听性脑干反应（ABR）测试。
电磁场频率为20 kHz，工作场所平均电场强度为21 - 38 kV/m，高于国家标准（<5 kV/m）。工作场所平均噪声水平为52 - 65 dBHL，在标准范围内。问卷显示，长期暴露于VLF EMFs可能会增加头痛、失眠和耳鸣的发生率。长期暴露组受试者DPOAE异常发生率高于短期暴露组和对照组（P<0.01）。在676、933、3616、5130、7253 Hz时，长期暴露组工人的DPOAE幅值明显低于短期暴露组和对照组。短期暴露组和对照组之间DPOAE异常发生率无明显差异。DPOAE异常受试者的ABR结果无明显异常。
工作场所平均电场强度明显低于健康标准。DPOAE的变化表明，暴露于高强度VLF EMFs对外毛细胞有细微、隐秘和局部的损害作用。应采取有效的干预措施。
