This document discusses mercury poisoning. It describes mercury as a heavy metal that exists in elemental, inorganic, and organic forms in the environment. Elemental mercury is liquid at room temperature and used in some products, while organic mercury is very toxic and can accumulate in aquatic animals. Exposure to mercury occurs mainly through fish consumption, occupational exposures like dentistry, and accidental exposures. Mercury poisoning can cause damage to the brain, kidneys, and nervous system. The most toxic form is organic mercury, which readily crosses the placenta and targets enzymes.

1. MERCURY POISONING Faisal Alshumrani
BIOL 5370

2. Do you know what mercury is
• It is heavy metal and bright silvery in appearance
• It is liquid and is non poisonous if swallowed.
• it volatilizes at room temp and inhalation of vapors is
toxic
• It gets widely distributed throughout the body and causes
toxic
damage to brain, kidney, peripheral nervous system, mucous
membranes.

3. Mercury compounds
 It exist in elemental, inorganic and organic form in environment.
 Elemental Hg : liquid at room temperature. It is used in some thermometers, dental
amalgams, fluorescent light bulbs, some electrical switches, mining, and some industrial
processes. It is released into the air when coal and other fossil fuels are burned.
 Organic Hg: are formed when mercury combines with carbon. Microscopic
organisms in water and soil can convert elemental and inorganic mercury into an organic
mercury compound, methylmercury, which accumulates in the food chain. (ex. Methyl
Hg, Ethyl Hg, and Methoxy methyl mercurial)
 Inorganic Hg: formed when mercury combines with other elements, such
as sulfur or oxygen, to form compounds or salts. Inorganic mercury compounds can
occur naturally in the environment. Inorganic mercury compounds are used in some
industrial processes and in the making of other chemicals.

4. Organic Mercury
 Most toxic form of Hg.
 It primarily targets enzymes.
 It readily crosses placenta and is secreted in breast milk
 These are extremely toxic to fetus.
 Methyl Hg can build up to certain level in aquatic animals.
 It is lipid soluble and gets widely distributed throughout the
body.
 SOURCES : Fungicides, seed preservatives, mercury
containing vaccines, fish consumption.

5. THIMEROSAL
 Despite being banned in 1999, the FDA still approves thimerosal in up to 60
percent of flu vaccines, many which are approved for children every flu.
• Thimerosal is a mercury containing compound that is a known
human carcinogen, mutagen, teratogen and immune system
disruptor at levels below 1 part-per-million, and a compound to
causes anaphylactic shock. It is also recognized as a reproductive
and fetal toxin with no established toxicologically safe level of
exposure for humans meaning even the a nanogram may be toxic.
• Thimerosal contains ethylmercury, which is cleared from the
human body more quickly than methylmercury, and is therefore
less likely to cause any harm.
What is the purpose of Thimerosal?
Thimerosal is added to vials of vaccine that contain more than one dose (multi-dose
vials) to prevent growth of germs, like bacteria and fungi.

6. Exposure to mercury occurs via:
 Diet : primarily through consumption of fish, also in some crops.
 Occupationally : manufacturing of laboratory equipment, electrical control devices, mercury
amalgams used in dentistry, extraction of gold.
 Accidental exposures
How People Are Exposed to Mercury:
Elemental mercury: People may be exposed when they breathe air containing elemental mercury vapors.
Vapors may be present in such workplaces as dental offices and locations where mercury has been spilled or
released. In the body, elemental mercury can be converted to inorganic mercury
Inorganic Mercury: People may be exposed if they work where inorganic mercury compounds are used.
Organic Mercury: People may be exposed when they eat fish or shellfish contaminated with
methylmercury. Methylmercury can pass through the placenta, exposing the developing fetus.
How do people expose to organic
mercury?

7. Toxicity
 Acute toxicity :
1. Inhalation of mercury vapor causes ( Chemical pneumonia, pulmonary
oedema, increased salivation)
2. CNS symptoms like ( Ataxia, restriction of field of vision, delirium,
polyneuropathy)
 Chronic toxicity: Kidney toxicity involves either renal tubular necrosis or
autoimmune glomerulonephritis, Immune dysfunctions, disruption of various
other lymphocyte subpopulations.
 Mechanism of toxicity: High affinity binding of divalent mercury to
sulfhydryl group in proteins ( altering function); disruption of microtubule
formation; interruption of protein/DNA synthesis: generation of ROS.

8. References
Mercury toxicity and treatment: A review of the literature.
(2011, December 12). PubMed Central (PMC).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3253456/#
B51
Mercury. (2009, November). Centers for Disease Control and
Prevention.
https://www.cdc.gov/biomonitoring/pdf/Mercury_FactShee
t.pdf
Thimerosal and vaccines. (2020, August 25). Centers for
Disease Control and Prevention.
https://www.cdc.gov/vaccinesafety/concerns/thimerosal/in
dex.html