Mercury

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Mercury

• Kristen Krisulevicz
• March 2, 2006

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Mercury Up close personal

• ? The only metal that is
• liquid at room temperature.
• ? Heavy! 1 teaspoon weighs approx. 70g!
• ? Symbol Hg derived from the Greek word
  hydraqrgyros meaning watersilver.
• ? Can be found as the free metal, inorganic
  salt, or organic mercury. Forms are
  interchangeable.

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Wait, how much Mercury is released in the
environment?!

• ? 30,000 tons released annually into the
  atmosphere by degassing from the Earths oceans
  and crust.
• ? 8-10,000 tons released by human activities such
  as burning household and industrial wastes and
  fossil fuels.
• ? Coal can contain up to 1ppm of Mercury.

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Form 1 Elemental Mercury

• ? Found in washing machines, thermostats,
  batteries. Mercury containing relays activate
  airbags and anti-lock brakes.
• ? Mercury amalgams as fillings in teeth.
• ? Used in folk medicine and voodoo.
• Little absorption of free metallic mercury from
  the gastrointestinal tract.
• Digestion of 220ml (3.0kg) needed to experience
  tremors, irritability, forgetfulness, and
  fatigue.
• Mercury Vapor is toxic! Poisoning is common
  through this route.

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Hold your breath

• Inhaled (lipid soluble) -----? bloodstream/red
  blood cells. Converted to inorganic divalent
  (mercuric). Small amounts of non-oxidized
  elemental mercury still exist and readily cross
  blood/brain barrier into CNS toxic effects!
• ACUTE EXPOSURE bronchitis pneumonia due to
  lung damage. Fever, chills, confusion, vomiting.
• CHRONIC EXPOSURE tremors, gingivitis, insomnia,
  memory loss, anorexia.
• WARNING Women chronically exposed to metallic
  mercury vapor show a higher frequency of
  menstrual disturbances, spontaneous abortions,
  and complications of pregnancy.

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Elemental Mercury Case Studies

• Gold mining in the Amazon Basin
• Mercury used to extract gold from crushed rock.
  Mercury/gold amalgam heated to remove Mercury.
  Vapor is toxic and inhaled by gold refiners.
• Dental amalgam manufacture
• 4 adults were acutely exposed to Mercury vapor.
  Symptoms of nausea, breathlessness and chest
  pains. All 4 involved died 11-24 days after
  exposure with post-mortem blood levels ranging
  from 58-369 ug/litre.
• Accidental contamination
• August 1994 More than 500 ppl in Belle Glade FL
  were contaminated after three children found
  55lbs of metallic mercury which had been dumped.
  20 families had to be evacuated.

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Form 2 Inorganic Mercury

• ? Mercuric nitrate used in hatting industry to
  remove rabbit fun from skins. Chronic exposure
  led to Mad Hatter syndrome with symptoms of
  tremor, excitability, shyness and nervousness.
• ? Highy toxic and corrosive. If swallowed 10 is
  absorbed. Poorly lipid soluble and accumulate in
  the kidney causing renal damage.
• ? Favorite agent for committing suicide.
  Corrosive ulceration of the intestines bleeding
  necrosis followed by shock and circulatory
  collapse. If victim survives renal failure
  occurs within 24 hours due to the damage in the
  proximal tubular epithelium of the kidney.
• ? Bind to a wide range of enzyme systems with a
  particular affinity for proteins containing SH
  groups. Bind to microsomes and mitochondria
  causing cell death.
• ? In the kidney, induces synthesis of
  metallothionein, a metal binding protein, and is
  found localized in lysosomes.

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Inorganic Mercury Case Studies

• Crema de Belleza
• Calomel (HgCl) is less corrosive and toxic. Known
  to be responsible for pink disease.
• Between September 1995 and May 1996, there were
  cases of Mercury posioning in Arizona, Texas, New
  Mexico and California. The mercury containing
  beauty crème Crema del Belleza contained 6-10
  Mercury by weight. 238 people used the crème
  which resulted in urine samples containing high
  Mercury levels. Even people in the same
  household of crème users who never used the
  product personally experienced elevated mercury
  levels in their urine.

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Form 3 Organic Mercury Compounds

• ? Most important member methylmercury (MM).
• ? Lethal dose 10-60 mg/kg body weight.
• ? More lipid soluble than inorganic salts.
  Readily cross blood/brain barrier.
• ? MM concentrates in red blood cells.
• ? Neurological effects when levels are at or
  above 25-50mg. Destruction of neurons in visual
  cortex.
• ? Effects transmission at the neuromuscular
  junction by reducing binding of acetylcholine to
  its receptor.
• ? MM binds to tubulin. We need functional
  microtubules for normal development? may explain
  why infants who died in utero had abnormal
  oranization of neurons in the cerebral cortex.
• ? Major route of excretion faeces
• ? Main source of MM consumption of fish! FDA
  have set a limit of 1ppm of mercury in fish.

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Organic Mercury Compounds Case Studies

• Minamata Disease
• 1953 Mercury containing wastes were released
  into the Minamata bay in Japan where they were
  methylated to form MM. Being fat-soluble it was
  incorporated into the food chain. 52 people died
  immediately from eating the fish. Others
  suffered degenerative neurological problems.
• 1972 Large quantities of wheat and barley
  treated with MM as a fungicide before planting
  were accidentally released as food quality grain
  in Iraq. 450 people died after eating bread made
  from the grain and over 6,500 people were
  hospitalized.

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Help! I have Mercury Posioning!

• D-Penicillamine oral medication. Forms a
  complex with Mercury which is excreted in urine.
  (Cannot be used safely on patients with renal
  failure).
• Not used for treating organic mercury poisoning.
  Initially leads to higher blood levels of
  mercury.
• DMSA agent of choice. Treat poisoning of both
  inorganic and organic mercurial compounds.
• Resins Polithiol used orally to improve the
  removal of MM. Helps prevent reabsorption lower
  down the gastrointestinal tract.

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