Simkó Myrtill
Division of Environmental Physiology, Department of Cell Biology and Biosystems Technology, University of Rostock, D-18059 Rostock, Germany.
Curr Med Chem. 2007;14(10):1141-52. doi: 10.2174/092986707780362835.
Epidemiologic and experimental research on the potential carcinogenic effects of extremely low frequency electromagnetic fields (ELF-EMF) has been performed for a long time. Epidemiologic studies regarding ELF-EMF-exposure have focused primarily on leukaemia development due to residential sources in children and adults, and from occupational exposure in adults, but also on other kinds of cancer. Genotoxic investigations of EMF have shown contradictory results, a biological mechanism is still lacking that can explain the link between cancer development and ELF-EMF-exposure. Recent laboratory research has attempted to show general biological effects, and such that could be related to cancer development and/or promotion. Metabolic processes which generate oxidants and antioxidants can be influenced by environmental factors, such as ELF-EMF. Increased ELF-EMF exposure can modify the activity of the organism by reactive oxygen species leading to oxidative stress. It is well established that free radicals can interact with DNA resulting in single strand breaks. DNA damage could become a site of mutation, a key step to carcinogenesis. Furthermore, different cell types react differently to the same stimulus, because of their cell type specific redox status. The modulation of cellular redox balance by the enhancement of oxidative intermediates, or the inhibition or reduction of antioxidants, is discussed in this review. An additional aspect of free radicals is their function to influence other illnesses such as Parkinson's and Alzheimer's diseases. On the other hand, modulation of antioxidants by ELF-EMF can lower the intracellular defence activity promoting the development of DNA damage. It has also been demonstrated that low levels of reactive oxygen species trigger intracellular signals that involve the transcription of genes and leading to responses including cell proliferation and apoptosis. In this review, a general overview is given about oxidative stress, as well as experimental studies are reviewed as they are related to changes in oxidant and antioxidant content after ELF-EMF exposure inducing different biological effects. Finally, we conclude from our review that modulations on the oxidant and antioxidant level through ELF-EMF exposure can play a causal role in cancer development.
关于极低频电磁场（ELF-EMF）潜在致癌作用的流行病学和实验研究已经开展了很长时间。关于ELF-EMF暴露的流行病学研究主要集中在儿童和成人因居住环境暴露以及成人职业暴露导致的白血病发病情况，同时也关注其他类型的癌症。电磁场的遗传毒性研究结果相互矛盾，目前仍缺乏能够解释癌症发生与ELF-EMF暴露之间联系的生物学机制。近期的实验室研究试图揭示一般生物学效应，以及可能与癌症发生和/或促进相关的效应。产生氧化剂和抗氧化剂的代谢过程会受到环境因素的影响，如ELF-EMF。ELF-EMF暴露增加可通过活性氧导致氧化应激，从而改变生物体的活性。自由基可与DNA相互作用导致单链断裂，这一点已得到充分证实。DNA损伤可能成为突变位点，是致癌过程的关键一步。此外，由于不同细胞类型具有特定的细胞类型特异性氧化还原状态，它们对相同刺激的反应也不同。本综述讨论了通过增强氧化中间体或抑制或减少抗氧化剂来调节细胞氧化还原平衡的情况。自由基的另一个作用是影响其他疾病，如帕金森病和阿尔茨海默病。另一方面，ELF-EMF对抗氧化剂的调节可降低细胞内防御活性，促进DNA损伤的发生。研究还表明，低水平的活性氧会触发涉及基因转录的细胞内信号，进而导致包括细胞增殖和凋亡在内的反应。在本综述中，我们对氧化应激进行了概述，并回顾了与ELF-EMF暴露后氧化剂和抗氧化剂含量变化相关的实验研究，这些变化会引发不同的生物学效应。最后，我们从综述中得出结论，ELF-EMF暴露对氧化剂和抗氧化剂水平的调节可能在癌症发生中起因果作用。
