A number of epidemiological studies have reported an association between human cancers and various surrogate measures of power frequency electromagnetic fields ( pf - emf ) , but the epidemiological studies done in the past 20 years as a whole showed no persuasive evidence on the causal link of interest mainly because of methodological flaws , in particular inadequate exposure assessment and scarcity of exposure parameters , if any , truly associated with cancer 摘要累积超过二十年的时问，虽有许多流行病学研究发现，极低频电磁场与人类癌症发生有关，但整体流行病学研究仍未能提供充分证据说明极低频电磁场与人类癌症之间是否具有因果关系；其中最主要的原因是，流行病学研究所使用的电磁场暴露评估方法并不完善，并且无法确定真正与癌症相关的暴露参数。
