and ElectroMagnetic Fields
(EMFs)
In the UK, the Radiation Protection Division (formerly the
NRPB) of the Health Protection Agency has the responsibility for
providing advice on exposure guidelines for electromagnetic
fields (EMFs). As part of a policy of ongoing evaluation
of scientific evidence and health risk assessment, advice on
limiting exposure to EMFs was reviewed in 2004. It was recommended
that the guidelines of the International Commission on Non-Ionizing
Radiation Protection (ICNIRP) for limiting exposure to EMFs between
0 and 300 GHz should be adopted in the UK. ICNIRP is an independent
scientific organisation responsible for providing guidance and
advice following a thorough review of current knowledge on the
effects of EMFs and an extensive consultation exercise.
Although the maximum guideline exposure level for the UK
public is 100 microtesla (μT), there is some
epidemiological evidence that time-weighted average exposure to
power frequency magnetic fields above 0.4 μT is associated with a
small increase in the absolute risk of leukaemia in children, from
about 1 in 20,000 to 1 in 10,000 a year. (Most UK homes have
background magnetic fields in the range 0.01 to 0.1 or 0.2 μT.) On
a relative scale, this corresponds to a doubling of the risk. In
the view of the HPA, the epidemiological evidence that
time-weighted average exposure to power frequency magnetic fields
above 0.4 μT is associated with a small absolute raised risk of
leukaemia in children is, at present, an observation for which
there is no sound scientific explanation. There is no clear
evidence of a carcinogenic effect of extremely low frequency (ELF)
electromagnetic fields (as from power lines) in adults, and no
plausible biological explanation of the association can be obtained
from experiments with animals or from cellular and molecular
studies.
Alternative explanations for this epidemiological
association are possible; for example, potential bias in
the selection of control children with whom leukaemia cases were
compared in some studies and chance variations resulting from small
numbers of individuals affected. Thus any judgements developed on
the assumption that the association is causal would be subject to a
very high level of uncertainty. It has therefore been concluded
that currently the results of these studies, taken individually, or
as collectively reviewed by expert groups, are insufficient either
to make a conclusive judgement on validity or to quantify
appropriate restrictions.
More recently, a study by Dr. Draper and colleagues from the
Childhood Cancer Research Group at Oxford, found
higher rates of childhood leukaemia among children whose address at
birth was close to major high voltage power lines compared with
those who lived further away. Draper and colleagues estimated that,
of the 400-420 cases of childhood leukaemia that occur annually in
England and Wales, their results suggest that about five might be
associated with living in proximity to high voltage power lines.
While the study identified a significant increase in the relative
risk for leukaemia in children, it remains unclear whether this is
related directly to magnetic field exposure.
More information on this study is
here.
The Health Protection Agency's radiation protection
division (HPA-RPD) keeps the world-wide research findings
on EMF continually under review. In 2004, on the basis of a
comprehensive review of the existing body of research to date, the
HPA-RPD, previously the National Radiological Protection Board,
recommended the adoption of new EMF exposure guidelines in this
country. In addition, in view of the scientific uncertainties, the
HPA recommended the Government ''consider the need for further
precautionary measures" in relation to power frequency
electromagnetic fields. They have also noted that the majority of
elevated magnetic fields are due to variations in the electricity
supply and distribution system, the presence of substations and
equipment in the home rather than proximity to power lines.
Here is a
link to an item on a National Grid website displaying
graphically magnetic fields produced around power lines of various
voltages.
To ascertain the voltage of high
voltage lines or contact National Grid on 0845 702 3270 or
01926 653000. Alternatively, for lower voltage lines, the
electricity distribution network operating company covering the
area in question may be able to help.
Here is a link to a map on the National Grid website indicating
the areas covered by the various companies together with links to
each company’s website.
If you are concerned about EMF levels, it might be worthwhile
approaching either the electricity distribution network operating
company or the National Grid as appropriate to ask for EMF
measurements to be carried out. As far as we are aware, there is
not normally a charge.
More information on the subject of electromagnetic fields (EMFs)
and health is also available on the
HPA website
World
Health Organisation fact sheet
Childhood Cancer and Distance from High-Voltage Power Lines