Proposal by the National Radiological Protection Board (NRPB) to adopt the guidelines of the International Commission on Non-ionising Radiation Protection (ICNIRP) for limiting exposure to electric and magnetic field associated with the Electricity Supply



NRPB proposes to reduce the current guideline for exposure to magnetic fields associated with the electricity supply from 1,600 microtesla (µT) to the ICNIRP guideline of 100 microtesla (µT). This still leaves the UK with an exposure guideline 250 times higher than where an associated doubling of the risk of childhood leukaemia has been acknowledged by respected international bodies.
Professor Henshaw responds . . .

Professor Henshaw has responded to the NRPB proposals for public exposure to electric and magnetic fields (EMFs) from high voltage powerlines and the electricity supply generally, saying that in light of the considerable evidence of adverse health effects of exposure to such fields, the proposals should go much further.

Respected international bodies, including the International Agency for Research on Cancer (IARC) have accepted that epidemiological studies have shown a doubling of the risk of childhood leukaemia associated with magnetic fields above 0.4 microtesla (µT). This is below the level typically found near some fixed sources such as powerlines. In addition, a major report issued by the California Health Department in 2002 also indicated an increased risk of adult brain cancer, miscarriage and possibly other illness associated with exposure to EMFs from the electricity supply.

The proposal to limit public exposure to magnetic fields to 100 µT, 250 times higher than the 0.4 µT where a doubling of the risk childhood leukaemia is acknowledged, looks ridiculous when viewed alongside the well established practice for chemical carcinogens, where levels are set at least 1000 times below that where evidence of harmful effects have been found.

In the case of new fixed installations such as powerlines and electricity substations, some countries took action many years ago to severely limit public exposure. Sweden introduced a 0.2 µT limit in 1996, Switzerland 1.0 µT in 1999 and three Italian regions 0.2 µT in 2000. Such steps underline the need for the UK Government to act now in introducing a strict limit of say 0.2 µT in the case of all new fixed installations such as powerlines and sub-stations.

Professor Henshaw called upon the NRPB to follow the example of other countries and said:

“if such precaution is good enough for these countries why is it not good enough for the UK? There is now good scientific understanding of the way in which exposure to magnetic fields may increase the risk of a range of illnesses and further evidence is continuing to emerge. In particular, a body of studies in human populations has reported that magnetic fields at even low levels can disrupt the production in the pineal gland of the important hormone and natural anti-cancer agent melatonin. This may explain why a substantial body of studies have shown that exposure to magnetic fields may lead to increased risk of childhood leukaemia, adult brain cancer, miscarriage and depression. Our state of knowledge of the health risks of exposure to EMFs well exceeds that for some chemical carcinogens where strict regulatory action has been taken.”

Notes for Editors:

Professor Henshaw is available for interview, please contact the University of Bristol Marketing Office, tel. no. 0117 9288896 or 0117 9260353. Information may also be found on Professor Henshaw’s Group website: www.electric-fields.bris.ac.uk (under Stop Press at the bottom of the front page). Key web pages include:

A summary of the adverse health effects which have been associated with magnetic fields from the electricity supply now follows.

Health Effects of Exposure to Electric and Magnetic Fields from the Electricity Supply
Our knowledge of the adverse health effects of exposure to power frequency EMFs continues to grow and already well exceeds that which has prompted strict regulatory action for chemical pollutants. In particular, there have been significant advances in understanding of the effects of magnetic fields since the NRPB EMF Report of April 2001 and the California Health Dept EMF Report of June 2002. Below is a summary of key developments.

  • Melatonin - disruption in the body by magnetic fields.
    There are now at least 11 studies in human populations indicating that magnetic fields as low as 0.2 µT suppress the production of melatonin in the pineal gland. Melatonin is a power anti-oxidant which acts as a natural anti-cancer agent. Recent studies provide strong support for the ability of melatonin to regulate cancer risk. Reduced melatonin is also associated with depression and some studies have suggested a link with miscarriage.
    That melatonin deficiency increases the cancer risk of some cancers is well established in animals and is supported in humans by the observation of decreased cancer rates in the blind and partially sighted and increased breast cancer risk in night shift workers.

  • Childhood Leukaemia – increased risk with magnetic field exposures above 0.4 µT.
    Two pooled analyses of international studies, including the UK Childhood Cancer Study were published in 2000. Ahlbom et al. find a doubling of risk associated with magnetic fields above 0.4 µT. Greenland et al. find a 1.7-fold risk associated with magnetic fields above 0.3 µT.
    Four major organisations now agree that magnetic fields are a possible carcinogen: The US National Institute of Environmental Health Sciences (NIEHS), the International Agency for Research on Cancer (IARC), UK NRPB and the California Health Dept EMF Report all agree magnetic fields are a possible carcinogen.
    Separate studies have shown that melatonin is highly protective of leukaemogenic damage to the human and animal haemopoietic system such as from radiation and chemical carcinogens. This provides a plausible mechanism by which magnetic fields suppress melatonin thereby increasing the risk of childhood leukaemia. Website: www.dhs.ca.gov/ehib/emf/RiskEvaluation/Chapter8.pdf

  • Adult brain cancer– increased risk with magnetic field exposures above 0.3 µT.
    The California Health Department EMF Report of June 2002, reviews 32 epidemiological studies and concludes that there is an increased risk of brain cancer in adults associated with magnetic fields above 0.3 µT. A further study by Villeneuve et al. (2002) found a 5.6-fold increase in risk of glioblastoma multiforme brain cancers with magnetic field exposures. There is also laboratory evidence to suggest that magnetic fields both increase the growth of brain cancer cells in vitro. Website: www.dhs.ca.gov/ehib/emf/RiskEvaluation/Chapter9.pdf

  • Adult leukaemia.
    Chapter 6 of the NRPB April 2001 Report lists a group of studies showing increased risk of adult leukaemia with magnetic field exposures. Chapter 8 of the California Report reviews 39 studies of adult leukaemia where a clear majority have indicated increased risk with magnetic field exposures. As with childhood leukaemia, the suppression of melatonin by magnetic fields represents a plausible mechanism by which these fields cause increase risk.

  • Miscarriage.
    Chapter 13 of the California Health Dept EMF Report reviews a series of studies, some very recent, showing evidence of increased risk of miscarriage with magnetic field exposures and in some cases significantly so. The California Report estimates a 5 – 10% risk of miscarriage for magnetic field exposures above 1.6 µT. These findings emphasise the urgent need for further research into the link between magnetic fields and miscarriage. Website: www.dhs.ca.gov/ehib/emf/RiskEvaluation/Chapter13.pdf
    The Report estimates that in the State of California, 24,000 miscarriages per year could be caused by exposure to magnetic fields from the electricity supply. If the California estimates are correct, magnetic fields from the electricity supply could be responsible for one miscarriage every 12 minutes in the UK

  • Regulation.
    The ICNIRP limit is 100 µT, 250 higher than the 0.4 µT where a doubling of the risk of childhood leukaemia is seen.
    In the case of air pollution, some studies have shown an increased risk of lung cancer in relation to exposure to 2.5 µg m-3 of the chemical carcinogen benzo[a]pyrene. Accordingly, the UK Air Quality Committee recommended a permitted exposure 1,000 times lower than this at 2.5 ng m-3. Existing precaution exist for new fixed installations in Sweden, Switzerland, three Italian Regions, and a planned “zero tolerance” for schools in California. Websites: