Concern that "EMF" magnetic fields from power lines cause cancer.

In 2002, the International Agency for Research on Cancer (IARC, 2002) categorized extremely low frequency (ELF) (including the power frequencies of 50 and 60 Hz) magnetic fields as "possibly carcinogenic to humans." That was based on pooled analyses of epidemiological research that reported an association between exposure to low-level magnetic fields and childhood leukemia. In 2007 a task group of scientific experts convened by the World Health Organization (WHO) acknowledged the IARC categorization but found that the laboratory studies and other research results did not support the association. Taking all evidence into account WHO reported that it could not confirm the existence of any health consequences from exposure to low-level magnetic fields. There remains continuing concern by some people that exposure to power frequency magnetic fields may cause adverse health effects, particularly childhood leukemia. Public health authorities need to fully understand the reasons for that ongoing concern and effective ways to address it. This paper describes what drives the concern, including how people perceive risks, how WHO and other public health authorities assess scientific research to determine whether health risks exist and the conclusions they have reached about power frequency magnetic fields. This paper also addresses the scientific basis of international exposure guidelines for power frequency magnetic fields and what precautionary measures are warranted to address the concern.