Given his ratings, only a tiny handful of you probably saw Paul Holmes in his new slot on Prime a few weeks back, talking to Don Maisch, described as an Australian expert on the health effects of magnetic fields. More precisely, he’s doing a PhD in the Arts Faculty of Wollongong University on changes in the health status of Chronic Fatigue Syndrome patients following removal of excessive 50 Hz magnetic field exposure.
His performance on Holmes’ show had been quite impressive, as he walked up the driveway of a West Auckland house with a little black meter, reading off figures to the reporter, who oohed and tutted dutifully. Inside the house, which was directly under high-tension power lines, the magnetic field was up to 35milliGauss. This is about as high as magnetic fields in a human dwelling would ever get.
What no one thought to mention was that the Earth’s background magnetic field is about 500mG. The theory is that the alternating (50 Hz) fields generated by electric wires have some effect that the static field of the Earth doesn’t produce, but the evidence on this is contradictory to say the least. After 25 years of research, the most that can be said is that several studies have shown a slight positive correlation between magnetic field strength and incidence of childhood acute lymphoblastic leukaemia in children – enough to raise the incidence from a background rate of three per 100,000 up to about six per 100,000.
Whether the fields cause the leukaemias is another matter entirely. Some of the most rigorous studies have shown no such effect, and it is easy to think of possible confounding factors – power lines are more prevalent in areas dominated by industry and low-cost housing, and there may be many other things affecting the health of residents in such places. Tests on animals exposed to alternating fields of up to 20,000mG for more than a year have shown no increase in leukaemia rates.
The day after the Holmes programme I was drinking a coffee at a cafe in Hamilton when protesters against Transpower’s proposed 400kV transmission line marched past. I have some sympathy for their stance, and believe that Transpower hasn’t managed this process effectively. There are property rights issues, aesthetic values and commercial considerations which to date have not been properly addressed. There may be better ways to supply this country’s energy needs, through conservation, solar water heating and dispersed generating capacity. Alleged health risks, however, do not rate. This issue has been playing out overseas for decades and many millions of dollars has been spent researching health effects, with little result. In the US the total cost of the power line scare, including relocating lines and loss of property values was estimated by the White House Science Office to be over US$25 billion. Decisions about our energy future should not be based on claimed health effects that remain highly dubious.