Robin Smart: Planned Transpower high-voltage line unnecessary risk

Brian Leyland's recent Perspectives article made light of the health effects of high-voltage power lines on people living nearby.

Objectors to Transpower's planned giant pylons could, he said, "be absolutely sure, first, that if there is an effect, it is something like smoking one cigarette in a lifetime, and second, that the levels of radiation from appliances, electric blankets, magnetic bed underlays and the like in their own homes are higher".

He is wrong. I, like many New Zealanders including, apparently, Mr Leyland, was unaware of the risks from power lines until Transpower's proposal led me to search high-quality scientific journals.

I have incorporated the results of 83 studies of the issue in a review paper that is available on the notowers.co.nz website (see link below).

My own conclusion, shared by many others, is that there are risks. While some, including the well-known doubling or tripling of the rate of childhood leukaemia, are rare, others are common. Suicide and severe clinical depression and breast and lung cancer are among the many common conditions implicated, as are melanoma, adult leukaemia and brain tumours.

Bristol physicist Dennis Henshaw has detailed 12 epidemiological studies showing an increase in suicide and depression for those living near lines and being subjected to more than 0.1 micro tesla of magnetic radiation. He concluded that 60 of the 5087 suicides in Britain in the year of study could be attributed to lines.

He also noted the effects of corona ions, millions of which stream downwind from high-voltage lines. They focus the effects of smoke, vehicle exhausts and the like on people's respiratory tracts in their path by a factor of six.

Professor Henshaw concluded that 200 to 400 of the 25,700 lung cancer cases in Britain annually could be attributed to living near lines. Similarly, effects on melanoma could be responsible for 17 cases a year.

Of particular concern to New Zealanders is a study by Auckland University psychologist Ivan Beale on 540 people living near lines in Auckland, which was published in 1997. It concluded that magnetic-field exposure from the lines was high, averaging 0.67 micro tesla.

Dr Beale's research found statistically significant defects in two out of 10 special tests of performance. These related to the ability to remember numbers, self-esteem and depression. As exposure to magnetic fields increased, so did the effect, especially for women.

Mr Leyland suggested that radiation from household appliances, electric blankets and so on was stronger than that from lines. That is true. But these fields are only strong close to the appliance and weaken rapidly with distance. For example, a TV set gives out 1.4 micro tesla at 10cm, declining to 0.19 at 50cm.

More importantly, these items operate only for short periods. Radiation from nearby lines continues day and night for residents, especially women and children.

In homes away from lines, this background radiation is generally less than 0.1 micro tesla; in homes near lines it is more than that. The Auckland readings were among the highest found and ranged up to 19 micro tesla.

The health effects are all related to AC (alternating current) pulsatile fields. They are not found near constant direct current (DC) fields, which are similar to the Earth's natural field.

This has led for a call for high-voltage DC to be used more widely in New Zealand, as is the case commonly overseas. Australia has many such lines, as do many European countries, the United States, Canada and a host of others, including China.

They are safer and much cheaper than AC, especially underground.

Mr Leyland said the cost of undergrounding Transpower's planned transmission line would be 10 times that of overhead lines. That may be true for AC, but for underground DC the cost would probably be about 1.5 times more than overhead AC.

The economics depend on the cost of land. The Public Works Act makes land for lines cheap because it largely prohibits compensation more than 65m from the lines. This is not the case overseas.

High-voltage DC is in use in the Cook Strait cable. Those opposing Transpower's plan point to the use of underground and overhead (with its lower pylons) DC in other countries, and also to the trend to generate close to cities.

Also, no one seems to know what power is planned for the proposed line because there is no new generation to the south.

* Robin Smart, an Auckland urologist, is a member of the Whitford Ratepayers Association. His home is 300m from the proposed line.