極低頻電磁場暴露與癌症之流行病學——文獻探討

An Epidemiological Review on Exposure to Extremely-Low-Frequency Electromagnetic Fields and Cancer

本文簡述極低頻電磁場之物理學特性及其於環境中之發生源，並回顧自1979年以來探討極低頻電磁場暴露與癌症發生可能相關之流行病學研究。本文就環境中極低頻電磁場可能之暴露來源，分別歸納居家內部環境、職業場所及家用電氣設備等極低頻電磁場暴露與癌症間之研究。此外，本文亦討論極低頻電磁場可能之致癌機轉。到目前為止，流行病學研究尚無法提供明確的證據說明極低頻電磁場與癌症發生間之因果關係，主要的原因在於研究設計上之缺失及研究執行上的限制。此外，極低頻電磁場造成癌症發生機轉迄今未明，亦無法提供確切証據來支持兩者間之因果關係；儘管如此，多數流行病學研究結果卻頗一致，指出極低頻電磁場與某些癌症間存在有正向相關，此統計相關之一致性，值得作更進一步的探討，以釐清兩者間可能存在之因果關係。由文獻回顧吾等建議在台灣地區進行社區性之流行病學研究。同時對台灣地區之輸配電系統之分佈、附近居民暴露於極低頻電磁場（特別是磁場）之狀況、以及家中常用電器所產生之極低頻電磁場之強度作進一步之暴露評估，以為制定各種預防措施之參考。

The present study reviewed recent epidemiological studies which place emphasis upon the association of cancer with exposure to extremely-low-frequency electromagnetic fields (ELF-EMF). A brief description of the physical properties and environmental sources of extremely-low-frequency electromagnetic fields was also included. Studies were discussed and summarized according to the research categories defined by the potential sources of ELF-EMF, i.e., residences, working places, and electrical appliances. To date, the role of ELF-EMF in the causation of human cancer was still inconclusive mainly because of the methodological issues. The paucity of mechanism of interaction between ELF-EMF and carcinogenesis implicates the interpretation of results of epidemiological studies. Nevertheless, the consistent findings showing a positive association between exposure to ELF-EMF (especially magnetic fields) and some specific cancers were observed and called for further investigations in order to disentangle the causal relationships, if any, between ELF-EMF and carcinogenesis. It is also recommended a well-designed community-based epidemiological study in Taiwan. Meanwhile, the formulation of strategies in preventing exposure to ELF-EMF will benefit from a field survey of environmental ELF-EMF from external power lines and domestic appliances in the communities of Taiwan.