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Powerfrequency EMF Summary up to 2000Extremely low frequency EMFs index » Overview | Power lines | Substations | Electrical wiring | Electrical appliances This article has been kept as it is a good indicator as to how long these issues have been known about and contested in official circles.
Electromagnetic interactions are now being recognised as the basis of bio-chemical actions and life itself. In the mid 1980's US scientist Eldon Byrd, who worked for the US Navy, described their findings: The Russian and US military have continued to spend vast sums on bio-electromagnetics research. [2] We are not suggesting that these things happen with the normal fields from mains electricity, but wish to point out that electromagnetic fields can be used to control life processes. In May 1994, the European Parliament passed amendments to the proposed Physical Agents Directive which called on all EU Governments to take initiatives for regulations and standards to aim at limiting the exposure of workers and the general public to electromagnetic fields according to the ALARA (As Low As Reasonably Achievable) principle. This included corridors of land near high-tension wires where housing would be banned, and the introduction of systems of indemnification and compulsory purchase of properties with significantly elevated EM fields. These amendments were not endorsed by the Commission, and the last Conservative UK Government stated its opposition to the whole of the Physical Agents Directive, which it saw as an unnecessary burden on both industry and government. In March 1999 the European Parliament approved the Tamino Proposals [3]. They require that stringent basic restrictions and EMF exposure levels must be based on the best available scientific data and advice. Member States are to lay down minimum safety distances from electrical equipment, and minimum distances from public buildings, housing and workplaces for the siting of high-voltage transmission lines, radar equipment and broadcasting and re-broadcasting transmitters, including cellular phone base stations. In the UK the NRPB is responsible for providing guidance on these matters, together with the Committee on Medical Aspects and Radiation in the Environment (COMARE). Their advice goes to the Health and Safety Executive who help the Government produce policy documents, but as these matters cross departmental and ministerial boundaries it is particularly difficult to draft Policy. The present Government's Science and Technology Committee is currently reviewing the quality of advice it receives from the National Radiological Protection Board (NRPB), to make sure government policies are based on the best available scientific data and advice (see above). The Secretary of State for Trade and Industry also has the duty, under the Electricity Act 1989, to protect the public from the dangers arising from the generation, transmission or supply of electricity. The NRPB advice was summarised by Lord Inglewood in Parliament on 23 March 1995 as: "The NRPB ... has concluded that the evidence does not establish that exposure to electromagnetic fields is a cause of cancer, although it does provide some evidence that the possibility exists, which justifies moving forward with research". Please note: The current UK guidelines for EMFs are not intended to protect people against chronic health problems, such as cancer, depression, Alzheimer's Disease, etc. Dr Roger Clarke, the Director of the NRPB, is on record [4] as saying that if they did recognise the reality of these effects the Guidance levels would have to come down by orders of magnitude. In the case of power frequency magnetic fields by a factor of about 8000, to about 200 nanotesla (0.2 microtesla). They have admitted that there is "some weak evidence" (1992), "weak evidence" (1993), "some evidence" (1994), of association, but still not enough to prove a causal link, between low levels of power frequency magnetic fields and some types of cancer. It is important to realise that we still do not actually know the mechanisms by which smoking or asbestos cause cancer, but that has not stopped us taking appropriate preventative actions. In a January 1994 BBC1 Panorama programme, Sir Richard Doll stated that although a few years ago he did not believe that a link would be found, in the light of the most recent research results he was now much less confident. When pressed at a conference, Sir Richard, Chairman of the NRPB Advisory committee, admitted that, if he were on a planning committee and was asked to approve a new housing scheme and school next to 400kV lines, he said that he thought, as a planner, that he would have to say: "such a development would not seem very wise at present". [5] In 1995 the USA Department of Energy issued a very helpful booklet, free to all US citizens, entitled "Question and answers about EMF", which looks in a very open minded way at all the issues, allowing interested individuals to gain some understanding of the issues and make up their own minds about any action. Nothing like this level of useful, open minded, information has been produced by the UK authorities. The USA debate was dominated by an 800 page draft National Council on Radiation Protection (NCRP) Report [6 & 8]. The study, based on the first comprehensive review of the world's literature on low frequency EMF health effects, calls for strong action to curtail the exposure of the US population to such fields. It was first reported in the UK in the Powerwatch August 1995 Newsletter. The committee recommended that: * 200nT = 0.20 microtesla (uT); (see later for typical domestic levels) In June 1999 the National Institute of Environmental Health Sciences released a report in which its Director, Dr. Kenneth Olden, states that epidemiological data show a "fairly consistent pattern of a small, increased risk of childhood leukaemia and acute lymphocytic leukaemia in adults with increasing EMF exposure." Olden concludes that "inexpensive and safe reductions in exposures should be encouraged, through electric companies measuring fields in customers' homes and helping them identify sources of high fields". He also suggested that "the power industry continue the current US practice of siting power lines to reduce exposure." Sweden's National Electrical Safety Board (NESB) findings in 1993 and the 1999 NIEHS recommendations reinforce the precautionary principles outlined by five Swedish authorities in their 1996 pamphlet called: "Low-frequency Electrical and Magnetic Fields: The Precautionary Principle for National Authorities - Guidance for decision makers" [7]. The Swedish National Authorities recommend the following precautionary principle: They go on to look at what could be deemed to be normal magnetic field levels. The median values for homes and day nurseries is given as 100 nT (0.1 µT) in major towns and cities, and below 50 nT in smaller towns and rural areas. They re-iterated the policy that new schools, day-care centres and play groups should not be located in areas where ambient power-frequency magnetic fields are above 200 nanotesla (0.2 microtesla). Some leading multi-national corporations are already specifying precautionary levels (e.g. 0.1 µT max. in office areas, 0.3 µT max. in corridors, toilets, etc.) in design criteria for new office buildings. In signing the Maastricht treaty, the UK government agreed to apply the precautionary principle in its decision-making. Powerwatch believes that the UK should now adopt the European Parliament Tamino proposals. Environmental causes of ill-health are usually first identified by epidemiological studies investigating patterns of illness. One of the strongest studies is the 1992 Swedish paper by Feychting & Ahlbom. It investigated 436,503 people who had lived within 300 metres of a high voltage power line, and indicated a dose-response relationship with childhood leukaemia. It showed no effect below 0.1 µT, a doubling in relative risk by 0.2 µT and, although there were no cases between 0.2 and 0.3 µ, a tripling over 0.35 µT (microtesla). A 1995 combined re-analysis of this and a Danish study by Dr Olsen, continued to show this relationship with childhood leukaemia, with a five-fold increase in risk for exposures over 0.5 µT, a level 3000 times lower than the current UK exposure guidelines. Most, but not all, EMF epidemiological studies have shown elevated risks of childhood leukaemia in the range 1.1 to 4, with some studies showing even higher relative risk levels. The USA National Council on Radiation Protection (NCRP) committee of 11 top scientists charged with assessing published information on these issues has allowed a version of its epidemiology conclusions to be published [8]. This states: The weight of evidence supports an association of proximity to power lines and risk of, at least, childhood leukaemia, and the weight of evidence supports an association of putative occupational EMF exposure and increased risk of leukaemia and brain tumours ... In addition, other possible associations have begun to be examined that are plausible based on laboratory research on melatonin. These include breast cancer in women and prostate cancer in men ... Even effects which initially seem implausible in the laboratory may prove to be causative, as illustrated in the early difficulties in confirming carcinogenic effects of benzene and inhaled arsenic, known human carcinogens. The US National Research Council - National Academy of Sciences issued a report entitled "Possible Health Effects of Exposure to Residential Electric and Magnetic Fields" [9]. The most important aspect of this report is that it does establish and agree that even under the strictest possible standards of proof, there is a reliable, though low, statistical association between power lines and at least one form of cancer (childhood leukaemia). This fact in itself shows that we need to do more to find out why this relationship exists, and take prudent avoidance action in the meantime. A much acclaimed USA National Cancer Institute (NCI) study by Linet et al, was published in July 1997. Although some claimed that this was a "negative" study, it did find an association between childhood leukaemia and measured magnetic field levels very much in line with earlier studies: an increase in risk of about 1.4 times over 300 nT (0.3 µT), rising to a six-fold increase between 0.4 and 0.5 µT [10]. In June 1999 a team, led by Dr Lois Green, at the University of Toronto and the Hospital for Sick Children reported their findings that children with the highest exposures to EMFs were 4.5 times more likely to develop leukaemia than those with the lowest exposures [11]. The weight of evidence does link powerlines and electricity EMFs with childhood leukaemia, and in a number of studies, with brain tumours. The UK Childhood Cancer Study published 'proximity' paper in British Journal of Cancer in November 2000. "Childhood cancer and residential proximity to power lines" claims "no association" in the summary, but further reading of the paper reveals a 42% increase near to 275 kV and 400 kV high-voltage power lines. They were not able to check out the latest Bristol University findings. The UK NRPB issued what we see as a scientifically and morally flawed response statement. Another British Journal of Cancer Paper confirms high power-frequency magnetic fields ARE associated with a doubling of childhood leukaemia. A major meta-analysis of the original data from a large number of competent studies of 3,203 children with leukaemia and 10,338 children without showed that the few (62) children exposed to residential power-frequency magnetic fields above 0.4 microtesla (4mG) have TWICE the chance of developing leukaemia compared with the unexposed control children. Relative Risk = 2.0 (1.27-3.13), p=0.002 showing a high level of confidence in the result. Yet another meta-analysis, this time of 15 studies, published in the November issue of Epidemiology finds a 1.7 fold increase in childhood leukaemia at 0.3 microtesla. There have been too few electric field studies published to carry out a meaningful meta-analysis, but electric fields are also under suspicion. These studies are are reported here. There are various non-cancer effects which have been reported: Two studies now link EMF exposure to a raised incidence of Alzheimer's Disease [13]. Several recent studies have shown that field levels of 12 µT can completely block the growth inhibitory properties of melatonin, the body's naturally-produced oncostatic agent. They also reported that magnetic field levels at and above 1.2 µT, prevent the anti-cancer drug Tamoxifen from inhibiting breast cancer and brain tumour cell growth. A recent study showed up to a four-fold increase in testicular cancer in men exposed to moderately high power-frequency magnetic fields [14]. Sources of electric and magnetic fields: According to research, including some carried out by National Grid, most domestic ambient EMFs are caused by underground low voltage distribution cables. Fields well over 0.2 uT can be found in many houses due to such underground cables, and Powerwatch has found fields of up to ten microtesla. These are usually due to what are termed "net" currents. These are "stray" currents either flowing through the earth, or more usually through the wrong piece of cable or metal pipework. UK electricity companies inter-connect neutrals from different substations (allegedly necessary to prevent "over-voltage surges" occurring if the local neutral becomes broken). This greatly increases unnecessary net currents, which can be due to equipment or installation faults. This situation could be prevented relatively easily if the electricity supply industry chose to tackle the problem. The background power frequency magnetic field level in a UK house is usually around 40 nT (0.04 µT), and will generally range from about 15 nT to 90 nT. A number of houses and flats can have fields exceeding 1000 nT (1 µT) due to underground cables, and some rural overhead low-voltage street distribution cables also produce high EMFs. About 0.5% of UK homes have ambient fields above 200 nT (0.2 µT), and VERY FEW houses have regular exposure levels above 2000 nT (2 µT). European reports show mean domestic levels between 10 and 70 nT (0.01 to 0.07 µT) for houses, and around 100 nT (0.1 µT) in flats and apartments. Another common cause of elevated field levels is undetected faults in internal building wiring. Appliances in the house continue to work correctly, but cause high magnetic fields throughout large areas of the house. Powerwatch has found fields as high as 15 uT from this cause. The problem can be prevented by using "radial and tree" wiring methods instead of the usual UK "ring circuits". Powerwatch believes that a measured EMF assessment should be included in every full building survey. The initial tests could be carried out in about 15 minutes. If high or suspicious readings are found, then a more thorough survey would be necessary. More detailed information can be obtained by data-logging EMF measurements over a period of several days. There is increasing evidence that electric fields may also be a problem. [16,17,18] A number of scientific studies have found highly significant associations between higher than normal electric field levels and childhood cancer. Due to support from the Children with Leukaemia charity, both magnetic and electric fields are being measured in the landmark UK Childhood Cancer Study, the first results of which are due to be reported in December 1999. In the 1996 Ontario Hydro adult worker study conducted by Dr Anthony Miller of Toronto University [19], when they took both fields into account, the risk of developing leukaemia rose from 1.6 times to 11.2 times compared with unexposed workers. It is likely to be a similar risk for children. In order to minimise electric field levels, building wiring ideally needs to be enclosed in metal conduit or trunking, or screened mains cable should be used. Present day electric fields in many domestic properties greatly exceed the 10 volts per metre long term aim of the American NCRP report. We recommend that people who are concerned about the levels of electric fields in their houses should measure them. Powerwatch believes that it would now be prudent to work towards ensuring that power frequency magnetic fields are below 0.1 µT, and most electric fields below 10 volts/metre. A 1998 survey [20] suggested that the presence of overhead powerlines near a property reduced the number of potential buyers by around 80%, and substations reduced its desirability for about 57% of purchasers. It might take quite a lot longer to sell it. Several UK lending institutions consider property with overhead lines to be unsuitable security for a mortgage. Surveyors and valuers who responded to the survey believed that property values and marketability were adversely affected if substations, pylons, overhead or underground power lines were within 200 metres of a property. The value could be reduced by as much as 30% for a power line within 50 metres, and as much as 20% for substations. Where power lines go over a property a wayleave or easement is negotiated. A wayleave is a personal agreement between the electricity company and the landowner and usually ceases to have effect when the property is sold. It should then be re-negotiated. [21] National Grid and the Regional Electricity Companies have paid significant compensation for loss of development potential of land underneath high voltage overhead power lines. This compensation is not, however, easy to obtain, and each case is considered on its merits. The electricity supply industry is concerned about the various pending adverse health Court cases and other unfavourable publicity, and is currently in the process of setting up an £8,000,000 industry fund to help fight future liability claims. [22] Measurement of fields Powerwatch believes that every surveyor should carry a small, easy-to-use, electric and magnetic field monitor in order to make a basic assessment of the ambient magnetic fields. Typical instruments can vary in price from a few thousand pounds down to about £130 for small ELF Monitors. [23] Powerwatch hires hand-held meters which measure both electric and magnetic fields at £30 per week (as of 03/2000), including instructions and advice as to what measured readings might mean. Many people find this an inexpensive way of finding out whether or not they need to be concerned about EMF levels in their homes and workplaces. We also have advanced EMF data-loggers for use when a problem has been identified and readings need to be recorded at regular intervals. It is important that professional EMF surveyors are adequately trained - there is more to carrying out a complete assessment than simply walking about with a hand held EMF meter. Conclusions and recommendations It is quite iniquitous for commercial electricity companies to be able to make changes at will as 'permitted developments'. ALL significant electric cable changes should be subject to planning controls, with appropriate appeals procedures, and with requirements on the companies and Local Planning Authorities to inform all affected residents. A moratorium should immediately be imposed to prevent NEW building within agreed distances of overhead power lines. Some lines need greater distances (up to 250m), some are acceptable at much closer distances, depending on a number of technical considerations. Lines approaching these distances should have their electric and magnetic fields measured. Field minimisation should be achieved by enforcing the reduction of net currents from local substations and "balancing" overhead and underground lines for optimum magnetic field cancellation. Electric fields in houses should be reduced by returning to the old practice of using earthed metal conduit (as is still done in public buildings). This would add little to the total cost of a new house. Radial wiring should replace the present "ring-main" system of wiring, to avoid generating large magnetic fields. References |
