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Comments and Mail From Our Readers
March, April, and May 2001
Last modified on:
Thursday, September 12, 2002 08:11:42
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May 30, 2001
First let me thank you for providing such an informative web site. I am just starting my research on powerlines and it has helped a great deal. I do have one question for you, however. My family and I are thinking about buying a home that has high voltage power lines buried below the ground in an easement off the back of the property line. I am aware of the information regarding the health issues linked to living close to high tension power lines above the ground but have not been able to find any information on power lines below the ground. Are the risks similar? Also, the house gets all of its water supply from an underground well. Could these power lines also taint the water flowing from streams that may cross the path of the power lines into the well? I appreciate all your help on this matter.
Reply from Dr. Robert Goldberg: Most people concerned with possible EMF health effects attribute them to the magnetic field produced by power lines. Underground lines generally have the phases and return lines (neutrals) placed fairly close to each other in a common conduit and therefore there is a lot of cancellation of the magnetic fields from the out-of-phase fields. Running a distribution line underground is therefore considered a way of reducing magnetic field exposure (compared to an overhead line of the same capacity) even though you may actually be able to pass closer to the line on your property. Your best approach might be to make some measurements to determine the magnetic field levels on the parts of the property where the house and your family activities will be located (often the utility company will do this for the property owner at little or no charge). As a rule of thumb, one study determined that the average exposure from power and distribution lines for houses in the US is about one milligauss. Flowing water will have some induced electric fields as it passes through a magnetic field, depending on its conductivity and rate of flow. There is some concern, for example, that fish migrating in a stream and exposed to an electric field may become disoriented, but there is no strong evidence for this in wild (as opposed to laboratory experimental) situations. As far as I know, there is no indication that standing well water would be affected by a nearby underground power line: at most you might expect some ion interactions that would change the composition slightly in water passing through an electric or magnetic field. The electric field produced in the flowing water would be rapidly discharged into the soil. Regards, Bob
April 02, 2001
We have a client in California that would like to park new cars under high voltage transmission lines. They are concerned the EMF might damage the electronics and paint finishes of the new cars. We would like any information or the names of any of your members that might be familiar with EMF affects on new cars parked under high voltage lines.
Reply from Dr. Robert Goldberg: The issue you raise is an interesting one that, as far as I know, no one has looked at in detail. The type of weak electric and magnetic fields that people are concerned about as a health issue are unlikely to have any effect at all on the cars. There might be a weak buildup of electric charge on the car body which, in extreme cases, can produce a mild shock for someone touching the car body and completing the connection to ground (the car, on rubber tires, is insulated). I would not expect this charge to have any effect on the paint or electronics. Probably more of a concern are air ions that are generated at the line and which could cause corrosive atmospheric pollutants to precipitate in higher concentrations under the line. We have some literature on this, mostly in relation to toxic agents, radon, and infectious microorganisms like bacteria and viruses. Corona discharge on the lines also increase ozone levels (ozone would degrade rubber, etc.) but it seems unlikely in an open air situation that there would be a large enough increase in ozone levels at the ground to produce any substantial damage.
The most likely group to have investigated this is the Electric Power Research Institute (EPRI) in Palo Alto, CA. There is also an EPRI group at the High Voltage Transmission Research Center in Lenox, MA, that looks at powerline environmental effects. I am not sure who to contact within that group, but I'm sure someone in either organization could direct you. Regards, Bob
March 07, 2001
I am (as I'm sure there are many) a concerned parent of small children regarding the EMF issue. My husband and I are contemplating making an offer on a house/property in Placerville, CA. This is a beautiful property on 6.8 acres. But there are 2 major metal electrical (SMUD) towers at the back end of this property, about 3 to 4 acres from the house. The "wires" are of 230,000 volts, with double digit magnetic fields. My gut instinct is this is a very risky exposure. I don't know for sure, because I have been told and have read much conflicting information on this. Other than this EMF issue we absolutly love this property, but of course we don't want to put our children/family in any risk/danger of cancer or other health problems. Is there any advice you could give me regarding this??? Should we just move on and forget about this property?? Thanks for any help. Sincerely, Jamie in CA.
Reply from Dr. Robert Goldberg: Dear Jamie, The concern you raise is a common one and unfortunately there is no simple answer. Some studies suggest an increased cancer risk, while others do not. Most experts feel the risk is low, but in spite of 20 years of studies, there still remains a small unexplained statistically increased risk of childhood leukemia associated with living near a powerline, based on considering the results of all major recent epidemiological studies collectively. This risk seems to be associated with exposures to average magnetic field levels over 4 milligauss, but that does not really establish this reading as a critical safe/unsafe level based on the available research. If you want a quick summary of the risk and one approach to addressing it, try the article I wrote a few years ago available for purchase on our EMF-Link® web site. It is an article from EMF Health Report, Volume 4, Number 5, September/October, 1996 (118 Kb PDF format file) Price $8.00 entitled THREE COMMON QUESTIONS FROM THE REAL WORLD: ONE SCIENTIST'S ANSWERS.
Most concerns about EMF are basic and pragmatic: people worry about the purchase of a house near a power transmission line, a cellular phone tower proposed for their child's elementary school, their computer monitor, or industrial EMF sources. This article describes how one scientist responds to practical questions about the safety of EMFs based on ambiguous scientific data. It can be purchased on line by clicking the "Online Bookstore" button on the EMF-Link home page and looking under "articles from EMF Health Report." There are also detailed articles about some of the epidemiology studies and other research under some of the other buttons, but I think this Health Report article provides the most direct answer to your question. In many cases utility companies will come out and make measurements near your home to let you know if the magnetic field levels are unusually high. I would be very surprised if the readings are really at the 10s of milligauss level if you are beyond the right of way for the 230 kV line (I don't understand what you mean by 3-4 acres from the house since this is a measure of area not distance). Perhaps you should start by confirming the measurement. Making measurements is often harder with a home you are considering buying than one you own because the utility company doesn't want to be in the position of disrupting a sale, but if you get the seller's cooperation it should be possible. In this area, people frequently include an EMF survey in the normal home inspection done before a sale and make the sale conditional on meeting a particular magnetic field level. If you find the levels are no higher than the national average (about 1 milligauss in the US) you may feel better about your powerline. Utility companies also may be able to give you general information on the health effects research. Regards, Bob
Reader Response: Although I don't feel better or know anymore about EMF than I did before. Thank You for replying to my e-mail. I appreciate it.
Reply from Dr. Robert Goldberg: The EMF issue is complex and can be confusing, but if you are still concerned I hope you will take advantage of government publications and the material we have available on our web site to learn more about the basis for concern and the evidence supporting or refuting a possible cancer risk associated with powerline exposures. Regards, Bob
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