David Grant, scientific director of Leukemia Research said that the observed increase in leukemia risk for those living at distances greater than 60 m from a high voltage power line was most unlikely to be due to any residual electromagnetic field, or other exposures related to the power line. Therefore he thought that“It cannot be excluded that it is a statistical artefact.”
A study that only considers distance from a High Voltage Transmission Line (HVTL) as a factor in ill health or childhood leukaemia is a very crude measure, especially as it is widely accepted that it is exposures from sources within the home that are generally the primary source of residential exposures – unless you’re unlucky enough to live right next to a HVTL, or directly underneath one as seen in New Zealand, where levels can reach 40 mG.
A good example of the problem is illustrated by an aborted powerline/EMF study in Hobart, Tasmania by Dr. Ray Lowenthal at the Royal Hobart Hospital, conducted some years ago. Lowenthal’s hypothesis was to test if there was a connection between proximity to transmission lines and leukaemia rates. It was shelved when it was found that generally measured magnetic fields within the homes were higher than from nearby transmission and his hypothesis could not be tested.
In the many surveys I have done in Hobart, Melbourne and Adelaide it is a consistent observation that exposures from sources within the home (especially night time bed exposures) are the pre-dominant source of exposure. Generally (and very roughly) at the distance of 60 meters from a transmission line the magnetic field is well below that 4 mG (o.4 uT) figure. At 100 meters about 0.5 mG and at 200 meters nothing.
So this is the problem with the Draper study. The significance for the distances is far greater that would be expected for magnetic fields (but perhaps not for corina ions). Some evidence saw an increased risk in relation to distance from the line.
Whatever the case the Draper study does NOT exonerate HVTLs from being a possible factor in childhood leukaemia.
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