FAQ for Health Effects of Transmission Power Line Magnetic and Electric Fields

This FAQ is designed to answer in a brief and readily accessible format questions frequently asked about the dangers associated with exposure to magnetic and electric fields emitted by transmission power lines.

The questions contained herein confined only to issues associated with the extremely low frequency electro magnetic fields (ELF-EMF) associated with transmission power lines. Similar issues have been raised concerning the high frequency magnetic fields associated with cell phones. These high frequency fields have impacts that differ from those associated with power lines and, therefore, this FAQ does not apply to them.

1. What are transmission power lines?

a. They are those high voltage lines that carry power from power plants to substations or between substations. Generally, they carry voltage greater than 35 to 65 kV (kilovolts). Lines that carry power from substations to the ultimate users are called distribution lines. They generally use voltages under 35 kV. Transmission power lines radiate magnetic and electric fields that pulse sixty times per second. This is called extra-low frequency EMF (ELF-EMF).

2. How can I determine if a line is a transmission or distribution line?

a. One rule of thumb is to count the number of mushroom shaped insulators between the line and the structure that holds the line. If there are more than three such insulators, it is likely to be a transmission line. If there are around 7-12 insulators, the line probably carries 115 kV. Twelve or more suggests the line carries more than 300 kV.

3. I feel nothing unusual when I am near a transmission power line. Why might they be dangerous?

a. Transmission power lines emit two types of fields, electric and magnetic. Together they are called electro-magnetic fields, EMF. Magnetic fields are known to interact with animal tissues, and are therefore potentially dangerous. While a tiny minority can sense magnetic fields, most of us can detect neither magnetic nor electric fields.

4. Are magnetic fields from power lines dangerous to human health?

a. There is substantial evidence that exposure to extra-low frequency magnetic fields of an average intensity greater than 2 milligauss doubles the risk of a child contracting leukemia. There is very good evidence that even momentary exposure to ELF fields greater than 16 mG increase by a factor of 5 a woman will have a spontaneous abortion within the first 10 weeks of pregnancy. There is also evidence that these fields are associated with other diseases (see below). Exposures below 2 mG appear to have no adverse health effects. High frequency magnetic fields emitted by cell phones and TV station antennas are a different phenomena.

5. How common is magnetic field exposures at the dangerous levels.

a. Not very common. Less than 2% of the population experiences ELF magnetic fields that average more than 2 milligauss. Average US exposure is around 0.5-0.75 mG. The number of those who experience momentary exposures greater than 16 mG is not known.

6. Are electric fields from power lines dangerous to human health?

a. There is little evidence that electric fields at the intensities associated with power lines directly impact human health. However, these fields have the potential for indirectly inducing harmful reactions. It is undisputed that fields above 1 mV/m (millivolt per meter) can disrupt heart pacemakers and defibrillators. Electric fields of this intensity, while rare in general, are common immediately adjacent to transmission power lines. Also, one researcher claims that electric fields from power lines ionize particles in the air, and these particles are carcinogenic. This research has been validated by epidemiological evidence.

7. I live near a transmission power line. How do I know if I am in danger?

a. When assessing danger, distance is all-important. The current research seems to suggest that living further than 400 feet from a transmission line will provide an adequate margin of safety from magnetic fields. However, the very latest research suggests that pregnant women should never venture anywhere near a transmission power line, for even momentary exposure to high magnetic fields sharply enhances the risk of a miscarriage. They should avoid even driving under a transmission power line.

b. Those utilizing pace makers or automatic defibrillators should similarly avoid even momentarily venturing near transmission power lines.

c. Those concerned about the less-documented risks associated with particles ionized by electric fields should avoid outdoor exposures with 2000 feet downwind from transmission power lines.

8. Are lower voltage power lines (say 115 kV) safer than high voltage (345kV and above) lines?

a. The risks associated with electric fields directly correspond to a line’s voltage. Therefore, the risks associated with electric fields increase in tandem with the line’s voltage.

b. The better documented risks associated with a line’s magnetic field are associated with the current going through a line rather than its voltage. To deliver a given amount of power, utilities must push more current thorough low voltage lines than high voltage lines. Therefore, in-field measurements show the magnetic field under a 115 kV line is often greater than the field immediately under a 345 kV line. Also, high voltage lines are customarily built on wider rights of way than low voltage lines. Therefore, people tend to live closer to low voltage lines than they do to high voltage lines. For these reasons, low voltage transmission power lines generally pose a greater risk to human health than do high voltage lines. Lines with 65 kV or less usually emit very low levels of magnetic fields.

9. Can magnetic fields be reduced by physical barriers?

a. Not usually. Walls, houses, trees and the like are no impediment to magnetic fields. Field measurements indicate occupants of the front seats of cars experience an approximate 30% reduction in magnetic fields.

10. Can electric fields be reduced by physical barriers?

a. Yes they can. Furthermore, particles ionized by electric fields pose a danger only to those, like children, who are outside a good part of the day.

11. How strong is the evidence identifying an associated between ELF magnetic fields and human disease?

a. There is extremely strong evidence finding a relationship between ELF magnetic fields greater than 2 mG and childhood leukemia. This relationship has been a matter of scientific inquiry since 1979. Sixteen out of nineteen studies conducted since 1995 are now viewed as identifying a statistically significant relationship between magnetic fields greater than 2 to 4 mG and a two to four-fold increase in a child’s risk of contracting that disease.

b. There is very strong evidence finding a relationship between maximum ELF magnetic field exposure greater than 16 mG and a 6-fold increase in miscarriages.

c. There is strong evidence linking ELF magnetic fields and Alzheimer’s and Lou Gehrig’s disease (ALS).

d. There is substantial evidence linking ELF magnetic fields greater than 12 mG and breast cancer and strong evidence linking magnetic fields and the suppression of the therapeutic effects of the anti-cancer drug, tamoxifin.

12. How strong is the evidence linking electric fields and cancer?

a. There is only one source of studies linking ELF electric fields to the creation of cancer causing particles through ionization. However, a mechanistic process has been identified. It has been verified by in-field measurements, and validated through epidemiological studies.

13. Why have there not been follow up studies on the link between electric fields and cancer?

a. There is no constituency to promote the funding such studies. This is a big problem in this field (see below).

14. Why is there not more intensive research in the US on the link between ELF-EMF and cancer?

a. Only a small percentage of the population lives near enough to transmission power lines to be exposed to the dangerous magnetic fields of intensities greater than 2 mG. A far greater percentage may be exposed to dangerous fields from the lower voltage distribution lines, but, as far as we know, there has been no studies on the incidence of magnetic field exposures from distribution power lines. Furthermore, the utility industry aggressively acts to minimize such dangers through the issuance of exculpatory statements and its funding of research that downplays the dangers (See EPRI discussion below).

15. There are those who suggest non-ionizing radiation such as ELF-EMF contains too little energy influence animal tissues.

a. This formerly popular argument has largely fallen into disuse. Ionizing radiation (such as X-rays) contains sufficient energy to knock electrons out of their valiances, thereby creating chemically active ions. By-in-large, ELF-EMF does not contain sufficient energy to create ions. It was therefore argued ELF-EMF must be biologically inactive. The argument has largely fallen into disuse (except by John Muller-see the next question) because all knowledgeable scientists agree that magnetic fields have biological impacts. They clearly promote bone growth at high intensities, suppress melatonin production, and induce cells to emit stress proteins. The argument revolves around whether these recognized biological impacts imply potential human harm. (The electric fields immediately adjacent to power lines are ionizing, which is the genesis of the argument that electric fields are associated with cancer.)

16. Who are John Moulder and Peter Valberg, and why are they so vociferous in decrying the dangers of EMF?

a. John Moulder and Peter Valberg both earn substantial incomes from testifying for power companies that ELF-EMF is not dangerous. John Moulder is the most active, having been under retainer from five utilities simultaneously. Valberg is associated with Harvard University (although not a full-time faculty member). He has not done work in the field for at least five years.

17. Moulder and Valberg seem to be able to cite significant evidence that suggests there is no danger. How can that be?

a. In September of 2000, there was an extraordinary event, the publication of the British Journal article. In that article, the prime authors of all the significant epidemiological research of the past five years came together ad admitted their original research has come to invalid conclusions. Whereas they had originally concluded there was not a statistically significant relationship between ELF-EMF and cancer, they now conceded that their original research should have recognized the existence of such a significant relationship. These results were confirmed by two additional research groups. Moulder and Valberg, while aware of the new research, justify their assertions by pointing both to invalidated research and to “blue panels” that, relying upon the now-invalidated research, had found insufficient evidence for such a relationship. In addition, Moulder frequently distorts the findings of his references by pejoratively picking sentences out of context.

18. While Moulder and Valberg are biased by their personal financial considerations, are you not equally biased by your personal concern over EMF’s deleterious impact?

a. Yes.

19. Bodies such as the UK National Radiological Board and the comparable German authorities, while finding a link between ELF-EMF and cancer, have said it’s not worth worrying over. How can that be?

a. Europe employs on average higher voltages than does the US. Because of the physics, this means that European transmission power lines emit lower levels of magnetic fields than do US lines. Furthermore, most European countries, including the UK and Germany have prohibited the construction of transmission power lines near homes for many years. The US has no comparable restriction. As a result, only a negligible number of European homes experience high levels of ELF-EMF. However, such high-level exposures are common in the US. Accordingly, European conclusions on the low level of exposures do not apply to the US.

20. The IARC, a division of the World Health Organization has found a link between cancer and ELF-EMF. Yet, it seems extraordinarily cautious in its pronouncement of this link. Similarly, the National Radiological Board and the National Institute of Health seem to be very cautious in pronouncing the existence of a link. Why is this?

a. Electricity is essential to a modern society. Top level government bodies such as the IARC are concerned that issuing pronouncements will improve the welfare of the relatively small number exposed to high intensity fields, while endangering the prosperity of the majority of those who are not threatened by these fields. We should also not overlook the role of the utilities. As members of a regulated industry, the electric utilities have developed and deployed advanced lobbying tools. They have become very effective lobbyists who are able to influence policymakers on such matters.

21. Do FHA regulations allow the issuance of insured mortgages for homes when transmission power lines are so close to homes that, even in theory, the supporting polls could fall on the house?

a. No. FHA regulations prohibit the issuance of insured mortgages for houses very close to transmission power lines.

22. What is the current status of research?

a. Research funding is a problem. One logical source for such funding would be the utilities' own research arm, the EPRI (formerly, the Electric Power Research Institute). However, there is evidence the EPRI declines to fund follow-up research when the original research uncovers evidence of magnetic field's potential to cause disease. It fails to fund the follow-up research even when its own analysts suggest the additional research should be conducted.

b. The federal government completed in mid-1999 its $45 million EMFRapid study that recommended passive actions in general, but did recommend transmission power lines be sited so as to reduce magnetic field emissions. However, the EMFRapid study based many of its findings upon research that is now recognized to be invalid. Had it been based upon valid research, it is likely its recommendations would have been much stronger. Nevertheless, there has been little federal research since that date.

c. The California EMF project is just winding up. It has now released its findings. In its evaluation, it concludes magnetic fields likely cause childhood and adult leukemia, adult brain cancer, spontaneous abortions ,and ALS. The evaluation further concludes that magnetic fields possibly cause childhood brain cancer, female and male breast cancer, Alzheimers disease, suicide, and heart problems.

Courtesy :- http://www.powerlinefacts.com/FAQ.htm