The balance of evidence points to ill health effects of high voltage power lines in adults and children. Notably, studies have shown a higher incidence of leukaemias and brain tumours in children living near overhead power lines. But a number of other studies have failed to prove a link and many electricity authorities deny a connection.
In 1994 the UK government was subject to a court case by 50 children due to the installation of high voltage underground power lines in a residential street. A report of the UK National Radiological Protection Board in 1992 indicated that no evidence had been found establishing a link between power lines and cancer; in 1994 the person responsible for the study indicated that since then evidence had emerged suggesting that there could be an important link. A study by Bristol University scientists in 1999 identified a "causal" link between pylons and leukaemia. In 2001, following biggest-ever study of childhood cancer and electromagnetic fields, the UK National Radiological Protection Board's concluded that there is an increased danger (double the normal risk of one in 20,000) of childhood leukaemia in children living near or under high voltage power lines. More than 23,000 homes in the UK are situated within 50 m of power power lines. (In the US and some other countries, legislation prevents new homes being built near power lines and 50 m is considered a minimum buffer zone.) But some opponents say that "hissing" cables, known as the corona effect, can extend the risk several hundred metres from power lines.
In 1996 the US Academy of Sciences evaluated hundreds of scientific papers on the subject of the effect of electricity transmission lines and found no evidence that exposure to these electrical fields presented a hazard to human health. The report pointed out that housing near power lines tended to be poor, densely populated, and subject to heavier traffic emissions and industrial pollution; these, the report says, are the likely cause of the higher rate of cancers in children living near power lines.
In 1997 the US National Cancer Institute concluded after an 8 year study involving 1250 subjects that children who live near high-voltage power lines do not have a greater risk of developing cancer than other young people.
There is a very small elevation of risk among the group of children exposed to very high levels of magnetic fields. The extra risk from powerlines amounted to one additional case of childhood leukaemia every two years in the UK.