THALLIUM

1
THALLIUM

• By Matt Jadlowiec

2
Thallium
3
Introduction

• The discovery of Thallium was the consequence of
  deliberate research.
• William Crookes extracted selenium from the
  seleniferous mud deposits obtained from the lead
  chambers used to make sulphuric acid at the
  Tilkerode works in Harz.
• The residue left over was suppose to contain
  tellurium, but when the residue was examined
  spectroscopically a new bright green line was
  observed.
• The unknown element which was named Thallium as
  Crookes would explain in a paper On the
  existence of a new element, probably of the
  Sulphur group that accompanied the
  announcement of his discovery on March 30 1861.

4
Facts

• Thallium resembles the alkali metals sodium,
  potassium and in some cases lead.
• Thallium is obtained from the dust that is left
  over in the flues of pyrite burners that are used
  to manufacture sulphuric acid.
• It is the only metal that contains a soluble
  carbonate and an insoluble chloride
• It has a bluish-white color
• Easily deformed and softer than lead
• Is present at concentrations of 0.6-0.7 ppm in
  the earths crust

5
Uses

• Thallium is used in salts to treat scalp ring
  worm
• Creams containing Thallium were purchased over
  the counter until the 1950s
• Became a controlled substance after some
  fatalities occurred
• Thallium salts were then used therapeutically to
  treat night sweats cause by Tuberculosis,
  venereal diseases like syphilis, dysentery, and
  gout. (Didnt work that well)
• Thallium isotopes (201Tl) are used as a
  dipyridamole for myocardial imaging in patients
  who have coronary artery disease.
• Thallium salts are also used to make imitation
  jewellery, low-temperature thermometers, ceramic
  semiconductors, scintillation counters for
  radioactivity quantitation, and in optical
  lenses that are very refractive.

6
Exposure

• Can be by oral, dermal inhalation routes
• Can occur by accident through industrial exposure
  of workers in coal fired power plants, lead and
  cadmium smelting operations and glass factories.
• Can occur in communities that are near cement
  plants that emit Thallium dust.
• Since Thallium is chemically similar to potassium
  it is assimilated into plants and taken into the
  food chain, can be consumed by eating home grown
  vegetables and fruits making urinary level of
  Thallium exceed 75µg/litre.(Normal levels are
  less than 2µg/litre).
• Has been used as poison throughout history.
  Victims didnt even know poison was there so it
  was named the Perfect Poison

7
Perfect Poison

• The Lethal oral dose ranges from 0.5 to 1.0 g of
  soluble Thallium salts
• Salts can absorbed across the skin even gloves
  are being worn
• Gastrointestinal absorption is also very quick as
  cell membranes pose no barriers to Thallium Ions
  which can also cross placenta into developing
  fetus.
• Appears in urine one hour after exposure, but the
  elimination half-life varies between 2 and 30
  days.

8
Acute Exposure

• With acute intoxication, usually with a large
  single does there is an initial hypotension and
  bradaycardia owing to direct effects of the sinus
  node and cardiac muscle followed by hypertension
  and tachycardia due to vagal nerve degeneration.
• Myocardial necrosis may occur with dysrhythmias
  and heart failure.
• The nervous system problems range from peripheral
  neroupathies to an ascending paralysis, via coma
  to death from respiratory failure.
• If Thallium intake happens via Gastrointestinal
  tract symptoms include colic, nausea, vomiting,
  and diarrhoea will then be followed by
  centrilobular necrosis of the liver.
• If the person survives then symptoms of chronic
  exposure will occur though central and peropheral
  nervous system abnormalities may persist
  including ataxia, tremor, foot drop, and memory
  loss.

9
Chronic Exposure

• If intake occurs orally, within a few hours
  abdominal pain, and diarrhea will occur
  simulating food poisoning.
• Within hours to days, a painful tingling in the
  hands and feet (glove and stocking
  polyneuropathy) develops and turns into burning
  sensations that can accompanied by partial
  paralysis.
• The most shocking symptom though is alopecia, if
  death is delayed 2-4 weeks then the person hair
  will fall out completely.
• The combination of gastroenteritis,
  polyneuropathy, and alopecia are all peculiar to
  Thallium
• Hair loss is the most specific diagnostic clue.
• White streaks(Mees Lines) can be seen on
  fingernails and toenails. If Thallium intake has
  occurred over a long period of time.
• Can be followed by slowly progressive
  deterioration in visual function due to lesions
  in the retinal nerve fibres, and then
  convulsions, and even hallucinations.
• When death finally comes it is after the
  degeneration of the heart. Liver, and kidney
  cardiac and renal failure being the ultimate
  causes.

10
Method of Action

• The exact mechanism of Thallium toxicity is
  unclear.
• Like other heavy metals Thallium binds to
  sulphydryl groups of proteins and mitochondrial
  membranes which inhibits a range of enzymes
  leading to poisoning.
• Hair proteins form a tightly crossed linked
  structure with many bonds between adjacent
  sulphur atoms creating disulphide links. When
  thallium is present is creates thallium sulphur
  bonds which leads to a weak network which creates
  dark bands around the base of the hair which can
  only be seen under polarized light. This causes
  hair to break easily and fall out when being
  combed.
• Throughout the body Thallium ions (Tl 1.54Â)
  exchange with potassium ions (K 1.44Â) and
  interfere with oxidative phosphorylation by
  inhibiting Na/K ATPase.
• Thallium ions cross the blood brain barrier very
  easily and disturb neurotransmission.
• Axonal degeneration and swelling with distended
  mitochondria and secondary myelin loss all point
  to disruption of membrane integrity, due to the
  Na/K ATPase membrane pumps.
• Lens and optic nerves are normally rich in
  potassium ions and when Thallium is introduced it
  enables binding to the melanin-type pigments of
  the eye which affects function and precipitates
  damage resulting in swelling of the optic disc
  and visual deterioration.

11
Treatment

• For gastrointestinal uptake treatments include
  emesis, lavage and activated charcoal within the
  first few hours of ingestion. Repeated does my
  be applied since charcoal binds to Thallium very
  well.
• The Drug D-penicillamine has been used
  therapeutically, since it allows thallium ions to
  be excreted. Though must be applied cautiously.
• N-acetylcysteine and dithiothreitol were used
  early on but only made symptoms worse, and
  allowed the thallium to circulate into the blood.
• Dithiocarb was also used but allowed thallium to
  get into the nervous system making symptoms worse
  as well.
• Potassium chloride diuresis replaces thallium
  intracellulary and increases thallium excretion
  but, similary, may enhance toxicity by elevating
  thallium blood levels.
• The most effective antidote is the dye Prussian
  Blue (Potassium ferrichexacyanoferrate)
  (K4(Fe(CN)6)3) which exchanges postassium ions
  for the Thallium Ions resulting in a stable
  chemical complex, that is excreted.
• Its only of use in fecal excretion and dosages
  are given orally.
• Thallium can also be excreted against a
  concentration gradient through the
  gastrointestinal tract and in digestive juice
  like bile which trap the Thallium before it can
  reabsorbed.

12
Case Histories

• Four members of a political organization ate a
  snack given to them by their innocent host.
  Within 2 days all experienced abdominal pain and
  within a week this pain was followed by burning
  sensations and a loss of feeling in their hands
  and feet.
• After three weeks most of their hair had fallen
  out and, following this diagnostic sign, they
  were found to have high levels of Thallium in
  their blood and urine, shed hair and nail
  clippings.
• All 4 recovered after treatment.

13
Attempted Murder

• Middle aged women came to hospital with history
  of repeated hair loss over a period of 10months.
  Had pain in both legs and had experienced some
  gastrointestinal disturbance, with alternate
  diarrhea and constipation.
• Had lack of sensation in her fingertips and also
  tingling and numbness in her feet. Also reported
  slow loss of vision which had stared six months
  after the first attack of alopecia. Traces of
  Thallium were found in here blood and urine
• Later discovered her husband had repeatedly tried
  to poison to her with rat poison which contained
  Thallium salts. She still had partial blindness
  six years later.

14
Malicious Contamination

• 4 teenagers came to a hospital 3 days after 1 of
  them got some marzipan sweets expensively
  packaged in a box from a well know supplier.
• 2 of the teenagers each had once piece while the
  other two split a piece of the marzipan. The
  next day they experienced gastrointestinal pain
  and burning sensations along with tingling in
  their hands and feet.
• A tentative diagnosis of thallium poisoning was
  made and atomic absorption spectroscopy showed
  each piece of marzipan had a potentially fatal
  level of Thallium.
• Antidote therapy using Prussian Blue was
  administered. One of the teenagers who ate a
  piece almost died. The others developed
  hypertension, and tachycardia and then alopecia
  after about 3 weeks. All recovered without any
  long term effects.

15
The
END