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EXPOSURE TO
MERCURY
Humans come in contact with mercury through
environment, occupational and accidental exposure. An estimated 80% of used
mercury is eventually released back into the environment. Because it is easily
vaporised, air around chlorine-alkali plants, smelters, municipal incinerators,
sewage treatment plants and even contaminated soils may contain increased
levels of mercury. A primary route of exposure is through transport into
surface waters, where mercury becomes biomagnified in fish
tissues.
Workplace exposure to mercury occurs through
inhalation of contaminated air, direct skin contact with liquid mercury oral
exposure through contaminated hands, food etc.
The television program 60 MINUTES highlighted
concerns about mercury exposure in patients receiving "SILVER" DENTAL FILLINGS
WITH MERCURY -CONTAINING AMALGAM.
Accidents have resulted in several cases
of mercury poisoning in Michigan, USA in the past two years. Four members
of a family were killed after one member attempted to refine DENTAL AMALGAM
in his home while attempting to recover silver. High levels of mercury were
found throughout the house, including wrapped food inside the freezer. The
entire house had to be demolished and disposed of in a hazardous waste
landfill!!
A number of children have developed Mercury
poisoning after playing with small vials of mercury which they found at home
or school. These children were hospitalised when symptoms became so severe
that they could no longer walk. One contamination accident involved closing
a school for weeks and entailed environmental investigation of residencies,
cars, school buses, and day care centres.
METABOLISM AND
TOXICITY
In the human body, Mercury accumulates in the
liver, kidney, brain, and blood. Mercury may cause acute or chronic health
effects. Acute exposure (i.e., short term, high doses) is not as common today
due to greater precautions and decreased handling. However, severe acute
effects may include severe gastrointestinal damage, cardiovascular collapse,
or kidney failure, all of which could be fatal. Inhalation of 1-3 mg/m3 for
2-5 hours may cause headaches, salivation, metallic taste in the mouth, chills,
cough, fever, tremors, abdominal cramps, diarrhoea, nausea, vomiting, tightness
in the chest, difficulty breathing, fatigue, or lung irritation. Symptoms
may be delayed in onset for a number of hours.
Chronic effects include central nervous system
effects, kidney damage and birth defects. Genetic damage is also
suspected.
Nervous system effects. These are the most
critical effects of chronic mercury exposure from adult exposure as they
are consistent and pronounced. Elemental Mercury is dissolved in the blood
and is transported across the blood/brain barrier, oxidised and retained
in brain tissue. Elimination from the brain is slow, resulting in nerve tissue
accumulation. Symptoms of chronic Mercury exposure on the nervous system
include increased excitability, mental instability, tendency to weep, fine
tremors of the hands and feet, and personality changes. The term "Mad as
a Hatter" came from these symptoms which were a result of Mercury exposure
in workers manufacturing hats using a Mercury-containing
process.
Kidney effects: Kidney damage includes increased
protein in the urine and may result in kidney failure at high dose
exposure.
Birth defects: Neurological damage from Methyl
Mercury. The manifestations of mild exposure include delayed developmental
milestones, altered muscle tone and tendon reflexes, and depressed
intelligence.
Mercury exposure in children can cause a
severe form of poisoning termed acrodynia. Acrodynia is evidenced by pain
in the extremities, pinkness and peeling of the hands, feet and nose,
irritability, sweating, rapid heartbeat and loss of
mobility.
PRECAUTIONS FOR HEALTH CARE
WORKERS
Substitutes for Mercury -containing devices
should be used whenever possible; e.g. thermometers and sphygmomanometers.
When Mercury devices must be used, special precautions should be taken. These
devices should never be used on a cloth surface, such as upholstered chair
or in a room with a carpeted floor. If a spill occurred in such an area,
the upholstery or carpeting would need to be discarded, as it could not be
effectively decontaminated.
Children should never be left unattended
near these devices. If Mercury thermometers are used, a Mercury-spill kit
should be kept readily accessible. The kit should contain a sulphur powder
to suppress volatilisation and a collection device.
Today, a typical adult carries ten amalgams
weighing a total of about ten grams, of which five grams is mercury. Research
shows the rate at which mercury escapes amalgam is about half a gram of mercury
from these ten fillings over the ten-year life of these fillings, and most
of this mercury will be absorbed by the bearer of the amalgams. To put a
half-gram in context, consider these facts: Half a gram of mercury dropped
into a ten-acre lake warrants the promulgation of a fish advisory for the
lake in Minnesota; the tennis shoes with mercury in them that were banned
by the Minnesota legislature in 1994 contained half a gram of mercury per
shoe.
SO, MERCURY IS HIGHLY TOXIC AND SHOULD BE HANDLED
WITH CARE AND ATTENTION, IF AT ALL…….SO WHY ARE DENTISTS ALLOWED
TO PUT IT INTO OUR MOUTHS BY WAY OF AMALGAM DENTALS
FILLINGS????????????????????
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