by Terry
Ally
It is a modern convenience that most
people can't imagine life without.
At the same time, electricity has brought with it a byproduct known as
electromagnetic (EM) waves.
Scientists say these waves penetrate the human body, and the strong ones
cause very serious problems such as cancer, leukaemia, low sperm count,
birth defects, burns, Alzheimer diseases, while the weaker waves are
suspected of causing other diseases of the nervous system, damage to the
immune system and DNA, among other things.
People won't realise that these waves are dangerous because they are
invisible and don't really hurt when they bombard your body but
everything that has an electrical current flowing through it, from the
overhead electrical wires to the bar code scanners at checkout counters
in the supermarkets, has EM waves.
Almost every square inch of Barbados is covered with electromagnetic
waves as radars sweep the island and power lines crisscross our roads.
Though the subject is new in Barbados it is a 20-year controversy in
developed countries where scientists face-off on whether low-level EM
fields can harm people. (The low frequencies are called EM fields and
the high frequencies EM radiation).
The perception of harm is so real that the World Health Organisation
(WHO) is coordinating a US$100 million five-year international study
aimed at getting to the bottom of the issue.
Electromagnetic
waves
EM waves differ in intensity.
The very powerful ones are known as ionizing radiation whose frequencies
are extremely high, into the millions of gigahertz (GHz), and comes from
such things as x-rays and gamma rays (from certain types of radioactive
radiation). People working in X-ray departments shield themselves from
these rays while patients having tooth X-rays must wear a lead vest.
There is no dispute about the effects of ionising radiation but there is
with non-ionising radiation (NIR). NIR is divided into several
categories in the range of 0 Hz to 300 GHz (see box). EM radiation which
comes from appliances with frequencies between 1 MHz and 10 GHz (see box
left) penetrate exposed tissues and produce heating because the energy
is absorbed in the tissue, said the WHO.
The lower the frequency, the greater the
penetration, said the world body. The WHO said when the heating causes
body temperature to rise over 1C then it begins to have an adverse
effect on health.
The person may not be able to perform physical and mental tasks with the
same efficiency as before. Induced heating may affect the development of
a foetus while birth defects would occur only if the temperature rose
between 2-3C for hours.
It can also affect male fertility and lead to the development of eye
opacities such as cataracts.
"It is important to emphasise that most RF studies conducted at
frequencies exceeding 1 MHz, examined the results of acute exposure to
high levels of RF fields - an exposure that is not normally found in
everyday life," said the WHO.
Frequencies below 1 MHz do not produce significant heating but they
induce electric currents and fields in tissues.
The muscle and nerves in the body rely on natural electrical inputs to
function. The natural level in the body (referred to as "background
levels") is about 10 milliamperes per square meter (mA/m2) but
currents which exceed 100 mA/m2 can interfere with the normal
functioning of the body and cause involuntary muscle contractions.
Other effects have been reported but
not confirmed. One is that the currents reduce the production of the
hormone melatonin at night. Melatonin is secreted mainly at night from a
gland in the brain believed to be able to slow the growth of some cancer
cells, so if there is less being producted some researchers believe
there is an increased risk of cancer.
High-voltage
power lines
Power lines emit one of the smallest
frequencies.
In Barbados it is 50 Hz and at this frequency, it does not cause heating
but can induce electrical currents.
Are these problematic, especially for people who live directly beneath
or besides high power lines?
In 1992 a study sent shivers through Americans because it drew an
association between children suffering lymphoblastic leukaemia who lived
next to high voltage lines.
Since then there were numerous studies either proving or disproving the
results.
The latest and largest study, of 1 258 children by the National Cancer
Institute in Bethesda, US, found no increased risk of cancer to
children. It also found that 12 per cent of children living in houses
with the highest EMFs (stronger than 2 mG) were about 24 per cent more
likely to develop leukaemia than the 45 per cent of children who lived
in houses with the lowest EMF (less than .65 mG).
But the lead investigator said that the effect was small and probably
due to chance.
In their September 1996 fact sheet on EMF in the Workplace three
American Government departments, in reviewing cancer risk among workers
in power utility companies said that there were incidents of cancer and
leukaemia among them but it was not clear-cut whether the occupational
exposure to power was the cause or whether it helped to propel it.
Concern
With the numerous studies and
counter-studies, who do you believe? What should you do?
Dr. Michael Milburn, biophysicist and co-author of the book
Electromagnetic Fields and Your Health, said research was very
challenging given today's environment.
"In order to ascertain the impact
one would need to do epidemiological studies which requires statistical
information and that is difficult because of lack of a control group.
If you had just about everybody who smoked in society the only people
can be really compared were people who smoke two packs of cigarettes per
day with people who smoked two-and-a-half packs," he said.
"What has happened today is that just about everybody is exposed to
electromagnetic fields."
His advice is "prudent avoidance" which is to locate
"hotspots" and minimise or avoid contact with high levels of
EM radiation.
As you move away from the object the EMF level quickly falls away.
Distances sould be maintained where exposure would be equal to the
background level of the building.
So that if you locate hotspots in a room, instead of placing a chair or
a bed in that location, an ornamental table could be used, instead. One
house in St. Philip, with electrical wiring in the walls, carried a
background level of 3-4 mG which increased towards the roof while
another house in Christ Church, with wiring in the floor, had a
background level of 0 mG.
Another house in Christ Church, close to the airport radar and with high
voltage lines a few feet above the roof, registered 15.9 mG on the
master bedroom's balcony, which is under the power lines while the
master bedroom was 8.4 mG.
Computers and televisions tended to measure about 100 mG one inch from
the screen but quickly fell away to 5 mG about two feet away while
higher measurements came from the side and back of the appliances.
A commercial hair-dryer measured 24 mG while a hand-held dryer was 4.9
mG. The level in a car was around 4 mG.
There are no exposure limits for these appliances but the Swedish
Government has mandated that computer screen be designed with a limit of
2.5 mG.
There is a number of inexpensive meters on the market which can assist
with locating hotspots at home or the office as well as badges that a
person can wear which continuously measure and record exposure levels
and sound warnings if the level is high.
Other meters, the size of a business card can also detect whether your
microwave oven is leaking.
Due to the difficulty in conducting studies and reaching a conclusive
consensus Milburn argues that it would be better to take evasive action
today rather than discover 25 years later that it was a problem after
all.
Managing Director of the Barbados Light and Power Company, Frank
McConney, said that in the last 21 years there were 84 studies by
reputable agencies none of which, he maintained, found any connection
between radiation from power lines and illnesses and therefore
Barbadians should have no cause to worry.
However he could not comment on electrical equipment which operated on
higher frequencies.
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The WHO project
1 . To study the association
between ELF (less than 300 Hz) and the following diseases:
* Childhood
leukaemia: Some research
has indicated that children seem to be at a 50 per cent greater risk of
leukaemia when they live near high voltage electric power lines.
* Breast
cancer: There is mixed
evidence from laboratory studies that exposure to low-frequency EMF
suppress the nighttime rise in melatonin - a hormone that controls our
normal night and day rhythms. Some studies suggest that melatonin has a
suppressive effect on the proliferation of certain breast cancer cells
and even low-frequency fields may suppress this protective effect.
* Diseases
of the central nervous system:
Some recent epidemiological studies have suggested that exposure to
low-frequency EMF seems to be related to an increase in the incidence of
central nervous system diseases such as Alzheimer's disease and
amyotrophic lateral sclerosis.
2. To study the association between RF (300 Hz-300 GHz) and the
following diseases:
* Brain and
other head cancers: Well
defined international studies are needed to investigate the suggested
association between mobile telecommunication devises and these cancers.
* Other
health effects: Why do
some people experience headaches, skin rashes, or dizziness and
attribute it to EMF exposure but cannot reliably determine whether the
fields are on or off in blinded laboratory tests? These need to be
thoroughly investigated.
Electromagnetic
Fields
Microwaves
Extra High Frequency (EHF) 300 GHz - 30 GHz
Super High Frequency (SHF) 30 GHz - 3 GHz
Ultra High Frequency (UHF) 3 GHz - 300 MHz
Radiofrequency
(RF)
Very High Frequency (VHF) 300 MHz - 30 MHz
High Frequency (HF) 30 MHz - 3 MHz
Medium Frequency (MF) 3 MHz - 300 kHz
Low Frequency (LF) 300 kHz - 30 kHz
Very Low Frequency (VLF) 30 kHz - 3 kHz
Voice Frequency (VF) 3 kHz - 300 Hz
Extremely Low Frequency (ELF) 300 Hz - 30 Hz
Static
Fields
Sub ELF 30 Hz - 0 Hz
Common
Sources of EMF Radiation
Power lines (50 Hz)
Monitors/VDU (3-30 kHz)
AM Radio (30 kHz-3 MHz)
FM Radio (30-300 MHz)
Cell phones (300 MHz-3 GHz)
Televisions (300 MHz-3 GHz)
Microwave Ovens (300 MHz-3 GHz)
Radars/Microwave
Communications (3-30 GHz)
Precautionary
Measures
THERE are no safe limits, as yet, to
electromagnetic field exposure, however health activists recommend 2-3
mG. This is the cut-off point used by several epidemiological studies at
which level effects on cells were reported.
Sweden has also mandated that computer
screens should emit between 2.5 mG to 0.25 mG at 20 inches. Others
recommend that exposure should not exceed the "background"
level of your environment.
Other guidelines are:
- Increase space between yourself and
EMF sources as EMF falls off with distance;
- Stay at least 18 inches away from
computer and TV screens;
- Turn off appliances when not in use;
- Don't sit next to or behind computer
screens even if it is on the other side of the wall;
- If feasible turn off or unplug
waterbed heaters and electric blankets before going to bed;
- Don't place beds or cribs next to
major appliances nearby or on the other
side of the wall;
- Move electric clocks, clock radios,
and answering machines at least four feet from your bed;
- Place incandescent bulbs one foot
away and fluorescent 3 feet;
- Avoid using electric blankets and
hair blow dryers;
- Check the background level of your
home to ensure your daily exposure do not exceed it.
Governmental
Views
"Some of the epidemiological
evidence is suggestive of an association between surrogate measurements
of magnetic-field exposure and certain cancer outcomes ... (lack of
sufficient data) prevents the interference of cancer causality from
these associations at this time."
- USEPA Science Advisory Board 1991
"It has not been scientifically established that magnetic
fields of
extremely low frequency initiate or promote cancer or have any other
harmful effects on humans. However, it has not been scientifically
established that such fields are not harmful."
- Advisory Panel to Australian Minister of Health 1992
"The epidemiologic findings that have been reviewed provide no
firm evidence of the existence of a carcinogenic hazard from exposure
(to EMFs) ... the findings to date can be regarded only as sufficient to
justify formulating a hypothesis for testing by further
investigations."
- UK National Radiological Protection Board 1992
"The Danish and Swedish study supports the hypothesis of
previous studies that children living near high-current plants have an
increased frequency of cancer. But the results do not exclude the
possibility that the association might be due to chance."
- Danish Ministry of Health 1993
"We suspect that magnetic fields may pose certain risks to
health, but we cannot be certain ... There is good reason to exercise a
certain amount of caution."
- Swedish National Electrical Safety Board 1994
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