Epidemiological studies in the USA and Europe show a context between cancer by children and electromagnetic fields, which are generated by high-tension power lines or distributing systems; this applies already to exposures of a magnitude of 200 Nana-Tesla (nT).
other epidemiological studies references were collected that low-frequency EMF pose a factor for increased appearance of leukaemia and brain cancer by vocational exposing adult.

Examining the context between electromagnetic exposure and cancer risk in animal and cell experiments more exactly, you find that probably electric fields don't prompt cancer causally, but precipitate the onset and the expansion of a tumour by raising cell division rate and deadening the defence of cancer. These effects were already observed at a field intensity, which can appear in living areas.