Power lines. Power lines passing directly over people's homes. Power lines carry a high voltage power supply from a power source to sub-stations. They generate low frequency electromagnetic fields which, according to studies in Sweden and America, can make children living nearby more likely to develop leukaemia. Researchers have subjected cell cultures to electromagnetic fields similar to those emitted by power lines, and some found that the cells divided more rapidly, which could explain the disputed leukaemia findings. Many researchers are sceptical about these experiments, and the problem of how power lines could cause cancer is still unsolved.