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Comments and Mail From Our Readers
January and February 1999
Last modified on:
Thursday, September 12, 2002 08:21:36
Copyright © 1994-2008, Information Ventures, Inc.
February 24, 1999
Russia
Could you tell me please, those plastic computer screens that you can hang on your computer monitor, are they protecting from EMF radiation? Thanks.
Reply from Dr. Robert Goldberg: Some computer screens that are made of fabric mesh coated with an electrically conductive coating, or made of treated glass, will shield against electric fields. They must also have a ground wire or some similar current path to ground in order to be effective, and in some tests it was found that older screens (or those made incorrectly) lost their coating and were no longer conductive. It is relatively easy to tell if a screen is working because the static field on a screen that is not shielded will attract the hairs on your arm, dust, or a dry tissue held nearby. Many people concerned with EMF health effects believe it is the magnetic rather than the electric field component that is important. Magnetic fields from a monitor will not be shielded to any significant degree by the computer screens you describe, and the only effective way to address that issue is by the design of the monitor or with metal shielding that wraps around the unit. Regards, Bob
February 24, 1999
USA
A year and a half ago my son-in-law was injured at work. He was blasted by high voltage. He was off work for a period of time and still isn't the same. He was dead for 3 minutes. Please inform me of any information you may have on a matter such as this. We have found that there aren't many doctors who know very much about this field. His Workman's Comp is wanting to settle and we feel he needs more treatment but we don't know where to get the help we need. Please reply to my message as soon as possible. Thank You.
Reply from Dr. Robert Goldberg: We do not have much information on the medical treatment of electrical injury, only some theoretical and experimental papers on the nature of the damage produced. There is an occupational physician I know a few years back that did some work on assessing subtle damage from shocks and treatment of shock burns and he may be able to help you or refer you to someone who could. He is Dr. Paul Heroux and the last address I have for him is McGill University, 1140 Pine St., Montreal, Quebec H3A 1A3, Canada (514) 398-6988. Regards, Bob
February 22, 1999
USA
I am trying to find out some information about the hazards associated with electromagnetic fields around outdoor power transformers. I am planning on buying a new home in Maryland but the power company is going to put a power transformer in my front yard next to the driveway. These boxes are about 3 ft x 3 ft x 2 ft in size. I would like to know what the typical Gauss readings are around these boxes and how far you need to be to avoid any ill effects. Please provide me with whatever info you have, or provide me with an alternate contact person.
Reply from Dr. Robert Goldberg: These small transformers generally service only a few homes and produce relatively localized magnetic fields. The fields right on the box may be in the 100 mG range or more, but by 10 feet or so away they are usually at background levels. You may be able to get more specific information on the transformer around your new home from the utility company, or perhaps you can have them demonstrate the readings around a similar transformer in your neighborhood using a gauss meter. It is not possible to define a "safe" or "dangerous" level on the basis of health effects because research results are not that specific with regard to exposure levels and effects (dose-response). In a study of 1000 homes, measurements established that 1 mG is about average for magnetic fields from sources outside the home (such as powerlines and transformers), so I think that can be considered a reasonable background level. You will have to decide if your intended use of the yard puts you too close to the transformer and is likely to expose you or your family to above typical background levels for extended periods of time. Regards, Bob
February 21, 1999
USA
Dear Dr.Goldberg, My wife and I have had an ongoing dispute about the safely of electric blankets. I read a response you gave to a similar situation dated in 1995. My request is if you would provide us with any current information regarding the above subject matter or possibly direct us to a source where we can obtain this information specifically on magnetic fields, and electric fields.
Reply from Dr. Robert Goldberg: On the narrow issue of electric blanket effects, there has not been very much new information. A recently completed study done in California looked at melatonin levels for women using electric blankets and waterbeds and got very confusing results. I think this mostly reflects the fact that magnetic field exposure levels with newer models of blankets are getting closer to background levels, so that "exposed" and "control" subjects have overlapping exposures. Pending any new information, there does not seem to be an especially high effect from electric blanket use. However, electric blanket use has turned up as a risk factor in several recent epidemiological studies of cancer risk, although not at a high enough level to be statistically significant. I would consider electric blanket exposure similar to other appliance exposures: there is no particular risk associated with it, but it is also not possible to be sure it is completely without risk, so if you are concerned and have an easy way to avoid the exposure you may wish to do so. The broader issue of electromagnetic field health effects requires a much longer and more complex discussion. Our EMF Health Report is intended for just that purpose; to update people with the latest research developments and explain the scientific results and uncertainty. We try to discuss the risk issues objectively and provide you with clear information on what the evidence is rather than stress an authoritative conclusion. Our review of the research indicates that there are some clear biological effects that appear to extend to environmental levels of exposure, but it is very difficult with our present level of understanding to interpret the results as showing clear adverse human health effects. Regards, Bob
February 3, 1999
Korea
My name is Du Ram Han, student in Korea. I'm very interested in inactivation of microorganism by electromagnetic fields and many questions about it I have. We know that preservation of perishable food is a very challenging subject to human life. Especially it is said to be used to prevent the food from preventing the change of quality. I want to know whether there is any document or any research about the magnetic inactivation of microorganisms and so on. I'll appreciate very much if you send me information concerning the inactivation of microognisms by magnetic fields. I'm longing for your response. Thank You.
Reply from Dr. Robert Goldberg: There is a large amount of information in our database on using electromagnetic fields (usually microwaves) to inactivate microorganisms in food processing and medical devices (sterilization). A major issue is the existence of athermal effects, that is direct effects of the microwave radiation not related to heating that might indicate a resonant interaction with, for example, DNA structure. There are a small number of papers on using low frequency magnetic field effects on microorganisms. Generally this does not kill them, but it can affect growth characteristics. In some instances, for example in biofilm structures, weak DC electric fields have been used to improve sterilization, presumably by altering membrane or extracellular matrix characteristics. Information Ventures is a private company that reports on this type of technical literature as part of our business. We can provide you with citations and detailed original summaries of this literature from our EMF Database, but there is a charge. We do custom searches of our EMF Database at Information Ventures for a standard minimum search charge of $325.00 for the search and the first 25 abstracts, plus $2.00/abstract for any additional abstracts. Usually, people who would like to have a search done establish an account and maximum number of citations they wish to receive (e.g., $500.00 which would cover 112 abstracts) and give us as complete a description as possible of what information they are looking for. You indicate you are a student, so as an alternative you may be able to look for these citations yourself on public databases like MEDLINE via the internet (searchable without charge) or through your school resources. You might also want to look through the BENER Abstracts available on our web site and purchase a few that are related to your interest. If you would like to set up a full search, or if I can provide you with more information on the EMF Database, please feel free to contact me by e-mail. Regards, Bob
January 31, 1999
USA
I wonder if you could direct me to information regarding any health risks, especially risks to young children, associated with home satellite dishes. We recently had one installed in our house not far from the bedroom of my six year old. I have found considerable information regarding risks associated with power lines and cellular phones, but have found nothing that specifically discusses the risks associated with satellite dishes. I would be very grateful if you could direct me to this information, whether by subscription or purchasing articles. Thank you very much.
Reply from Dr. Robert Goldberg: Many of the EMF issues we are asked about have to be answered with caution, indicating that the risks or lack of risk is uncertain. In the case of satellite dishes or any antenna however, it is quite clear that there is no danger from EMF. These units function as receivers and do not produce a signal: they only collect a weak broadcast signal. There may be low-level EMF sources associated with the amplifier and cable, but the amount of energy leaked from these connections is likely to be below detectable limits. Cell phones and power lines are EMF sources and are a completely different issue. Regards, Bob
Reply from Reader: Thank you so much for your response. You have saved me several dozen gray hairs.
January 29, 1999
India
I wish to introduce myself as pursuing my Ph.D programme in Environmental Biotechnology at Bharathidasan University, Tiruchirapalli, India. I am interested in the field of Magnetobiology, my topic is "Effect of Pulsed Magnetic Field on the seedling growth and yield of Green gram and Sorghum". With respect to this you have any related information, it would be really of great help of you can send me the related information and other details to my address.
Reply from Dr. Robert Goldberg: Thanks for your interest. We are a small business and maintain a commercial computerized database of some 25,000 articles on electromagnetic field bioeffects research. Most of these feature original abstract summaries written by our scientific staff that provide detailed information on the experimental approach and results of these studies. These abstracts are made available in the form of a print publication (the BENER Digest Update) and as a complete set on CD-ROM. You can also purchase single articles from the material added to the BENER Digest Update in the past year on our web site from our IVI Online Web Store, and also find additional information on these abstracts and some samples (http://infoventures.com/emf/). The BENER Digest Update, available by subscription for $440.00 per year, surface mail or $480.00 with airmail delivery, provides about 200 of the newest abstracts per quarter in print form. The EMF Database is a more comprehensive collection which includes all the abstracts that are printed in the BENER Digest along with many more that are not published in print form. Approximately half the material we review each quarter is published in the digest: an additional (approximately) 1000 articles per year are added to the database. The database can be searched by any text word to deliver a comprehensive set of references on any EMF topic. We sell subscriptions to the EMF Database for $3,850.00 annually and distribute it on a quarterly basis in the form of CD-ROM disks containing the database and search software. There is an alternative for people who want a one-time review of a particular subject area at a more modest cost: we do custom searches of our EMF Database at Information Ventures for a standard minimum search charge of $325.00 for the search and the first 25 abstracts, plus $2.00/abstract for any additional abstracts. Usually, people who would like to have a search done establish an account and maximum number of citations they wish to receive (e.g., $500.00 which covers 112 abstracts) and give us as complete a description as possible of what information they are looking for. There is a substantial amount of material on magnetic field effects on plant growth, so you might want to limit it by frequency range or other field characteristics and provide more information on the types of effects you are interested in. If you would like to set up a search, or if I can provide you with more information on the EMF Database, please feel free to contact me by e-mail or phone. Regards, Bob
January 23, 1999
Jordan
I understand from your website the complexity of the EMF issue, but I would very much appreciate your evaluation of the situation in our home. We live in a groundfloor apartment, where a Transformer station from the Electricity Authority is situated directly below our bedroom (in the basement). I had an expert measure the EMF and he came up with the following results: at bedroom floor level 35 mG, at bed level 8 mG. Anywhere else it was much lower. Given the fact that we spent probably on average 8 hours in our bedroom, should I consider these levels unsafe? Also, when I discussed this problem with the Electricity Authority they stated the levels in this country are well within European levels. They refered to a measure in Tesla, I can't remember exactly how much. Are there other ways or units in which EMF is measured? What is the relation between mG (milligausse) and Tesla? Thank you in advance.
Reply from Dr. Robert Goldberg: As you describe your situation, it is likely that you are being exposed to magnetic field levels that would be substantially above average, at least for homes in the United States. I assume that the meter you used to make these measurements is reasonably accurate. In a study of 1000 homes conducted in the United States, the average exposure power-frequency magnetic field from external sources like power lines and substations was on the order of 1 milligauss (1.0 mG = 0.1 microtessla (uT): a tesla is 10 kilogauss or 10,000,000 mG). In studies of office workers, exposures of 2 mG are typical, with peaks up to 6 mG (i.e., 0.2 and 0.6 uT), but exposures of 35 mG or more can occur in many industrial settings. In occupational settings, the health risk information (based on epidemiology studies) does not clearly indicate that higher field levels produce greater risk of disease, only that there is a small increase in risk in some studies with certain occupations having usual exposures over 2-3 mG. It is not possible to say then if the exposures you measured in your bed area are "safe" or "dangerous," only that they appear to be substantially higher than what most people would be exposed to. Published research provides no information on residential exposure to such high field levels (above 2-3 mG on average). Because there are so few people exposed to such high levels in a residential setting, it would be hard to see anything other than a greatly increased risk in a population-based study. There is no indication in the available research information that people with very high exposures are at much greater risk, and in animal studies that "scale up" exposures to the 100-1000 mG level have not shown much stronger effects. However, if you are concerned, it would be reasonable to try to place yourself in a lower exposure situation. You indicated that fields are lower in other areas of your apartment which suggests that it may be possible to rearrange the use of your living space to spend less time in the higher field areas. Regards, Bob
January 19, 1999
USA
The specific information we are looking for: (1.) Is burying a transmission line (in this case 138 Kv) really safer
than having it overhead? We have read that it dissipates faster when it is underground, but if you are close to it, it may potentially be more dangerous than when it is overhead. (2.) Are there specifications for burying lines that will make it safer? If so, where can they be found? (3.) If the lines cannot be buried, what can be done to protect families living near lines? Specifically, within 100 feet. Thank you.
Reply from Dr. Robert Goldberg: In a typical overhead transmission line, the magnetic field produced by each individual phase (usually there are 3 phases) is cancelled by the out-of-phase fields produced by adjacent lines. Phase lines are spaced apart so that the air can act as insulation between them (reducing power loss from the fields one line induces in another and, of course, the risk of touching and shorting out), and the utilities like to maintain a certain distance for the safety of workers who may have to repair the lines. On the other hand, the closer the phase lines are to each other the more complete the cancellation, so that the strength of the magnetic field decreases more rapidly with distance from the lines.
Underground lines still produce magnetic fields, but the lines are placed together in a single conduit (which is less costly to bury than spacing them apart) using plastic or oil for insulation. Because the phase lines are close to each other they produce better cancelation. If the line runs a few feet underground, you may get more exposure walking over it than you would from an overhead line 20-30 feet above you, but for most of the area around the line the exposure will be less. At a distance of 100 feet, magnetic field exposure from a buried line should be substantially less than it would be for an overhead line carrying the same current. Even with overhead lines however, there are certain line configurations that maximize the field reduction due to phase, and the utility should know about this engineering. Of course, increasing the distance between you and the line by increasing the right-of-way or raising the line higher can also lower exposure for nearby homes.
The question of "safety" is always difficult for a utility since they generally do not accept the possibility of long-term risk from low level magnetic fields. Overhead lines meet existing safety standards, although the existing standards also do not provide for low level effects. Scientifically, it is hard to demonstrate such effects and expert bodies have generally adopted the position that the limited research results do not provide a basis for changing the standards. You may be able to argue for underground lines on the basis of aesthetics and lower risk of service loss (although this economic position is questionable because while underground lines are at much lower risk of interruption - from lightning strike, falling tree limbs, etc. - they are much more expensive to repair when something does go wrong). We do have some reports in our database that discuss overhead power line configurations that reduce magnetic field levels and a report that argues for undergrounding (based on conditions in Florida that may or may not apply to your area). If your utility does not have this information we can prepare a brief report, but it would cost a few hundred dollars, so I suggest you start by working with the utility. Regards, Bob
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