Power lines. Power lines passing directly over a housing estate. Power lines carry high voltage electricity from power stations. They generate low frequency electromagnetic fields which have been linked with increased incidences of leukaemia in children living nearby. One theory is that the field interacts with chemicals called free radicals within human cells. In 1996 there is no conclusive evidence proving a link between power lines and cancer. Household electrical appliances expose people to a higher field than power lines because they are much closer.