Hi all - here is a liklik story about Mercury, hope you can get
through it in one sitting.

Mercury is a very interesting substance. I remeber as a kid finding
a small bottle of mercury in an old workshop and finding myself
facinated by it. It was like water yet very heavy, it shined like
the other metals I was familiar with but flowed. I use to play around
with it in may hands, rolled it around on the floor, pick it up with
a magnet and did many other things to satisfy my curiousity. Little
did I know the potential danger I was exposing myself to, and may it
did affect me somehow, who knows??

Anually, the atmosphere and surface of the earth is exposed to about
36,000 tonns of mercury. The single largest source of mercury is the
natural outgassing from granite rock (about 30,000 tonns)-not too
sure about this process, if our mining collegue can enlighten us.
The metal fillings used in dentistry is made of mixtures of metals
containing mercury (amalgam). Some studies have shown high levels of
mercury in the blood of people with amalgam dental fillings, but the
general consensus is that they are safe.

The mining industry uses mercury to extract gold and other minerals
from the raw material as outline beautifully by VB. Great effort
should be made to dispose of the waste products of mineral
extraction. When this is not done mercury and other toxic substance
can pollute and contaminate the environment and cause serious health
problems in animals and humans.

Mercury can take different forms each having a different level of
toxicity. Basically there are three different forms as outline
belowed in order of toxicity:

1) Elemental ("natural") mercury (Hg 0) - this is essentially non
toxic,this what we find in the dental amalgams.

2) When exposed to other modifying (oxidising) chemicals elemental
mercury (Hg 0) can be ionised to Hg2+ --> this is more toxic then
Hg 0.

3) Further modification forms the very toxic forms (the alkyl Hg).

SO HOW DOES THE INOCENT ELEMENTAL MERCURY Hg 0 GET CORRUPTED??

a) In industry, the chemical modification of Hg 0 to Hg 2+ is
frequently accomplished by exposing Hg 0 to a strong oxidants
such as chlorine.

b) Hg 0 can also be bioconverted to both Hg2+ and alkyl Hg by
microorganism that exist in the human gut and in the bottom
sediments of rivers and lakes.

These modified and now toxic forms of mercury accumulate in the
acquatic food chain and reach their highest concentration in the
large fish. Humans in turn acquire them by eating these fish.

HOW DOES MERCURY AFFECT HUMAN HEALTH??

Mercury toxicity can be expressed in three ways.

1) Mercury changes the structure of many essential proteins in the
body, from collagen in skin to important enzymes for normal
functioning of the body, this change in protein structure render
these proteins dysfunctional and incabale of doing their jobs
(detail are beyond the scope of this summary).

2) Protein structure modification makes them suseptable to
autoimmune destruction as the bodies immune system no longer
recognised them as self, and mounts an attack against them.

3) The most toxic form of mercury the alkyl mercuries can easily
penetrate into the central nervous system causing brain damage.
Unborn children are also affected as mercury freely passes from
the mother to the fetus.

TOUGH LESSONS THE WORLD HAS LEARNT ABOUT MERCURY.
Much of what is known about the health effects of mercury has been
gained from investigations of the 1951 to 1963 industrial dumping of
Hg waste into the Minamata Bay, Japan. Fish in Minamata bay became
heavily ladened with Hg and humans around the area who relied on
these fish for protein in turn became intoxicated. The symptoms and
signs of heavy mercury intoxication included:

Ataxia - unsteady gait
impaired speech - slurred
visual field contriction
hearing loss
psychotic changes

Collectively, these symptoms have become to be known as Minamata
disease.

THE ANALYSIS OF MERCURY.
The analysis of blood, urine and hair for mercury levels is used to
determine exposure. Blood and urine levels correlate well with the
degree of toxicity.

Significant exposure is indicated when blood mercury levels
> 50micrograms (if exposure is the the alkyl mercuries)
> 200micrograms (if exposure is to Hg 2+ form).

THE WHO SAFTY STANDARD FOR DAILY EXPOSURE OF Hg IS 45Micrograms PER
DAY WITH A DAILY URINARY EXCRETION EXCEEDING 50Micrograms/DAY
INDICATING SIGNIFICANT EXPOSURE>>>>.

Treatment of mercury includes the administration of penicilamine
which binds mercury and mobilises it for quicker excretion.
Treatment is monitored by urinary mercury excretion.

......................................................................

We should continue to educate ourselve and the public regarding the
issue of toxic metals in relation to the mining industry

The points I want to stress here are:

1) We need to know what form of mercury are our people exposed to in
order to stratify them into appropriate risk levels, and
determine wheather or not treatment is needed.

2) To determine this, samples need to be taken from fish and other
aquatic animals in the area.

3) If it is found that levels of alkyl mercury in these fish are
high it would indicate the same in humans and would further
suggest that the general exposure of the environment has been
going for some time.

4) If the people around the area are intoxicated ((Minamata
disease), do they deserve treatment and if so who is to pay for
their treatment.

Cheers
poyap