【作者】 谢亮；

【导师】 姜槐；

【作者基本信息】 浙江大学 ， 劳动卫生与环境卫生学， 2006， 硕士

【摘要】 随着无线通讯事业的飞速发展,移动电话即手机正在全世界普及,由此引起的射频电磁场(以下简称“射频场”,radiofrequency electromagnetic fields,RF EMF)对人类健康的可能影响已经成为生物电磁学和环境医学研究的热点问题。移动电话的工作频率主要在800 MHz～3000 MHz,属射频波段。鉴于引起温升有害作用的4 W/kg阈值,国际非电离辐射防护委员会(International Commission on Non-Ionizing Radiation Protection,ICNIRP)制定了10-50安全系数的射频辐射全身卫生标准。然而,低于该标准即低强度的电磁波究竟是否会对生物体产生影响及其作用机制如何则是一个长期争论并困扰科学界的问题,致使在不同国家的电磁波卫生标准达数百倍乃至千倍的差距延续数十年至今。 总的来说,射频场的潜在危害效应较弱,尤其是短期暴露,对长期暴露的效应和机制认识也还很不够;电磁场的作用在人体、动物和细胞水平都存在明显个体差异。就目前来看,已有的研究结果还不能对射频场诱发的生物学效应和健康影响作出明确的结论,需把重点放在射频场的作用机制研究上。对射频场作用机制研究的一个首要问题就是了解细胞如何感应射频场的。已有研究结果提示电磁场的生物效应有细胞内信号转导途径的参与,但电磁场如何活化细更多还原

【Abstract】 Recent advances in wireless technology have resulted in the exponential rising use of mobile telecommunications around the world. So the increasing exposure to radiofrequency electromagnetic fields (RF EMF) emitted from mobile phone has raised wide concerns for the possible adverse effects of RF fields on human health. Epidemiological studies have indicated a relationship between cell phone use and the risk of human diseases, but conclusive correlation has not been well established. ICNIRP set up the RF exposure limits for whole body with 10-50 safety factors on the basis of the SAR threshold of 4 W/kg in which adverse heating effects may occur. However, whether low intensity electromagnetic waves may cause health effects is controversial and its mechanism is unclear, which led to remarkable differences in the EMF hygienic standards in different countries for over 10 years.Generally, the potential adverse effects induced by RF EMF are weak,especially short term exposure, while the effects and its mechanism of long term exposure remains vague. Individual differences of EMF-induced effects appear obviously in different levels of human, animal and cell. Researches on mechanisms of RF EMF become essential under the condition that no definite conclusion has been drawn on RF-induced biological effects and health influence. Reports suggested that cell signal transduction pathways could participate in biological effects of EMF, but it is not clear how EMF activates those pathways.Cell membrane receptor is the action site of the ligand. The special binding of receptor to its relevant ligand usually induces receptor clustering, which initiates signal transduction pathways. Previously, we have reported that 0.4 mT 50 Hz magnetic fields could induce the clustering of membrane EGFR, a 170-kD transmembrane glycoprotein of ErbB family of receptor tyrosine kinases (RTKs), which plays a crucial role in cell proliferation, differentiation and survival. In the present study, EGFR clustering was investigated to explore the initiative action induced by GSM 1800 MHz RF EMF.Litovitz put forward the temporally and spatially coherent theory that external MF only with both temporal coherence and spatial coherence may induce biological effects. Noise MF is an incoherent field and has no biological effects. Superposition of a noise MF (incoherent fields) can inhibit the response of biological systems to a coherent MF when the intensity of noise MF is similar to or bigger than the coherent fields. Litovitz has also shown that ornithine decarboxylase (ODC) activity enhancement in Mouse Fibroblast (L929) cells induced by exposure to 60 Hz magnetic fields can be inhibited completely by superposition of noise MF.In the present study, we investigated the possible effects of exposure to GSM 1800 MHz RF EMF on EGFR and its possible interference by noise MF. Chinese hamster Lung fibroblasts (CHL) cells were exposed to 1800 MHz RF EMF at different intensities with different modulation modes and sham exposure, including:1) continuous RF exposure modulated by 217 Hz for 15 minutes at average specific absorption rates (SARs) of 0.1, 0.5, 1, 2, and 4 W/kg, respectively;2) continuous RF exposure at SAR of 0.5 W/kg modulated by different frequencies including 217, 50 and 0 Hz for 15 minutes, respectively;3) continuous RF exposure modulated by 0 Hz at SARs of 1, 2, and 4 W/kg for 15 minutes, respectively;4) exposure to 2 uT noise MF for 15 minutes;5) exposure to RF modulated by 217 and 50 Hz at SAR of 0.5 W/kg combined with 2 uT noise MF for 15 minutes, respectively. Immediately after exposure, the cells were fixed with paraformaldehyde (PFA), blocked with goat serum, incubated with rabbit anti mouse EGFR antibody followed by goat anti rabbit IgG-FITC, stained with propidium iodide (PI), and observed with laser cofocal scanning microscope (LCSM). It showed that EGFR clustering was induced after exposure to GSM 1800 MHz RF EMF modulated by 217 Hz at SARs of 0.5, 1, 2, and 4 W/kg for 15 min as induced by 1 ng/ml EGF, but not at SAR of 0.1 W/kg. GSM 1800 MHz RF EMF modulated by 217 and 50 Hz at SAR of 0.5 W/kg for 15 min both induced EGFR clustering, while no EGF receptor clustering was found in cells after exposure to unmodulated RF EMF or 2 uT noise MF. In addition, superposition of 2 uT noise MF could inhibit the EGFR clustering induced by GSM 1800 MHz RF EMF.In conclusion, EGFR clustering in CHL cells could be induced by GSM 1800 MHz RF EMF at the SAR down to 0.5 W/kg, which could be inhibited by 2 uT noise MF. The modulation of wave may play an important role in the inducement of receptor clustering after RF exposure.更多还原