Power lines and cancer
Everything that uses or carries electricity, from household appliances to power lines, produces an electromagnetic field (EMF).
Although very high level exposure to magnetic fields can be harmful to people, there's no good evidence that being exposed to levels within the guidelines has effects on the body that could damage people's health. This guideline level is very conservative and is set far below the level at which any potentially harmful health effects have been seen, even assuming a worst-case scenario.
There is little strong evidence to link power lines to adult cancers, or to most types of childhood cancer. But some studies have suggested a statistical link between exposure to magnetic fields and a higher risk of childhood leukaemia. At the moment, we don't have enough convincing evidence to be sure whether the link is real, but if it were, the impact would be small - only around one per cent of childhood leukaemias.
Power lines and childhood leukaemia - the evidence isn't clear
It is difficult to carry out research into exposure to magnetic fields and risk of childhood leukaemia, and there is no clear indication of what should be measured and when. So research that puts together results from a number of different studies is useful to help get a clearer overview.
Two studies like this found that the very small number of children who were exposed to the highest magnetic fields had a higher risk of leukaemia (around one and a half times to twice the risk) than the children exposed to the lowest levels. But because the studies they were based on had very variable results, it wasn't possible to be sure that power lines or magnetic fields caused the higher risk, especially because there's no good explanation for how this might happen. However, the researchers said that problems with the studies were unlikely to be the whole explanation. Another study found a similar increased risk, but the result could have been a chance finding because the results weren't 'statistically significant'.
The International Agency for Research on Cancer evaluated the evidence and concluded it was 'limited'. They rated low frequency magnetic fields as a 'possible' cause of childhood leukaemia - which means that we can't rule a risk out. This conclusion was supported by a separate World Health Organisation review of the evidence.
Overall, at the moment it isn't possible to say with certainty whether or not being exposed to the highest levels of magnetic fields from power lines increases the chance of developing childhood leukaemia. There isn't a good suggestion for how magnetic fields could cause leukaemia, laboratory studies don't support a link and the results from individual studies are variable. But the studies combining several results together do seem to show a raised risk. This is likely to remain a difficult area to finally resolve.
However, even if the link seen in these studies is a real effect, the impact would be small as only around one to four per cent of children have the highest levels of exposure. And the evidence shows that there is no noticeable increase in risk for the lower levels of magnetic fields that most people are exposed to.
For more information about power lines, EMFs and cancer, visit the Health Protection Agency’s website.
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