Heavy metals mercury Source Adverse effects

Symptoms and Diseases: Adrenal gland dysfunction, anorexia, birth defects, brain damage, depression, dermatitis, dizziness, fatigue, hearing loss, hyperactivity, insomnia, kidney damage, memory loss, migraines, mood swings, nervousness, pain in limbs, skin rashes, schizophrenia, thyroid dysfunction, peripheral vision loss

How Mercury affects health:
Energy- mercury compounds inhibit the enzyme ________, which impairs energy production in all body cells
Nervous system- degeneration of nerve fibers and reduced motor conduction speed

1. Heavy MetalsHeavy Metals
BISC 312BISC 312
Simon Fraser UniversitySimon Fraser University
Onkar BainsOnkar Bains

2. What are heavy metals?What are heavy metals?

Refers to any metallic chemical element that has a relatively high Refers to any metallic chemical element that has a relatively high
density and is toxic or poisonous at low concentrationsdensity and is toxic or poisonous at low concentrations

Natural components of the Earth's crustNatural components of the Earth's crust

Cannot be __________ or __________Cannot be __________ or __________

Essentials:Essentials: ___________, ________, ________, _______ and ___________, ________, ________, _______ and
____________


Others, such as mercury, lead and cadmium have no known Others, such as mercury, lead and cadmium have no known
biological role (biological role (non-essentialnon-essential))

All of these metals are toxic if present in excessAll of these metals are toxic if present in excess

3. SourcesSources

Industrial and occupationalIndustrial and occupational

Hg in paper productionHg in paper production

Pb in paint and chemical industryPb in paint and chemical industry

________________________________

Hg in fungicidesHg in fungicides

________________________________

Pb in pottery glazes and at one time in pipesPb in pottery glazes and at one time in pipes

________________________________

Hg in amalgam fillings (controversial)Hg in amalgam fillings (controversial)

________________________________

Burning of leaded petrol (contains tetraethyl lead, an organometal)Burning of leaded petrol (contains tetraethyl lead, an organometal)

4. Chemical forms of heavy metalsChemical forms of heavy metals

___________ (inorganic)___________ (inorganic)

e.g. Hg, Pbe.g. Hg, Pb

As ___________ (inorganic)As ___________ (inorganic)

e.g. MgCle.g. MgCl
22, PbSO, PbSO
44…so found in different oxidation states…so found in different oxidation states

As ___________ compounds (organic)As ___________ compounds (organic)

A metal which is bound directly to the carbon of an organic A metal which is bound directly to the carbon of an organic
compoundcompound

e.g. (Ce.g. (C
22HH
55))
44Pb - Tetraethyl leadPb - Tetraethyl lead

5. MercuryMercury

6. MercuryMercury

50-75%50-75% of mercury released into environment related of mercury released into environment related
to human activitiesto human activities
Other Organic examples: dimethylmercury Hg(CH
3
)
2
____________________ is most commonly found organic mercury compound in the
environment

7. Sources/UsesSources/Uses

ThermometersThermometers

Dental amalgam [alloy of Hg with another metals Dental amalgam [alloy of Hg with another metals
(usually Ag)](usually Ag)]

Others: tunafish, swordfish, felt, algaecides, floor Others: tunafish, swordfish, felt, algaecides, floor
waxes, adhesives, fabric softeners, chlorine production, waxes, adhesives, fabric softeners, chlorine production,
contact lens solution, preparation H, diureticscontact lens solution, preparation H, diuretics

8. UsesUses

One important use of mercury One important use of mercury
compounds was in hatmakingcompounds was in hatmaking

200 years ago, the furs used to 200 years ago, the furs used to
make beaver felt hats was dipped make beaver felt hats was dipped
into ______________________ into ______________________
solution as a preservative and to solution as a preservative and to
soften the animal hairssoften the animal hairs

Unfortunately workers in felt hat Unfortunately workers in felt hat
trade absorbed mercury through trade absorbed mercury through
their skins; resulting mercury their skins; resulting mercury
poisoning caused shaking and poisoning caused shaking and
slurred speech, being known as slurred speech, being known as
""hatter's diseasehatter's disease", which is believed ", which is believed
to have inspired the character of to have inspired the character of
the Mad Hatter in Lewis Carroll's the Mad Hatter in Lewis Carroll's
Alice in WonderlandAlice in Wonderland

9. Mercury speciationMercury speciation

14. Adverse effectsAdverse effects

Symptoms and Diseases:Symptoms and Diseases: Adrenal gland dysfunction, anorexia, Adrenal gland dysfunction, anorexia,
birth defects, brain damage, depression, dermatitis, dizziness, birth defects, brain damage, depression, dermatitis, dizziness,
fatigue, hearing loss, hyperactivity, insomnia, kidney damage, fatigue, hearing loss, hyperactivity, insomnia, kidney damage,
memory loss, migraines, mood swings, nervousness, pain in memory loss, migraines, mood swings, nervousness, pain in
limbs, skin rashes, schizophrenia, thyroid dysfunction, peripheral limbs, skin rashes, schizophrenia, thyroid dysfunction, peripheral
vision lossvision loss

How Mercury affects health:How Mercury affects health:

Energy-Energy- mercury compounds inhibit the enzyme ________, which mercury compounds inhibit the enzyme ________, which
impairs energy production in all body cellsimpairs energy production in all body cells

Nervous system-Nervous system- degeneration of nerve fibers and reduced motor degeneration of nerve fibers and reduced motor
conduction speedconduction speed

15. Adverse effectsAdverse effects

Carcinogenic EffectsCarcinogenic Effects

Carcinogenic effects of methylmercury are inconclusiveCarcinogenic effects of methylmercury are inconclusive

Renal tumors have been seen in lab studies involving rats, but Renal tumors have been seen in lab studies involving rats, but
only at very high concentrationsonly at very high concentrations

Immune System EffectsImmune System Effects

Effects of methylmercury on immune system are still poorly Effects of methylmercury on immune system are still poorly
understood, but studies are continually being conductedunderstood, but studies are continually being conducted

Studies suggest that exposure to methylmercury could Studies suggest that exposure to methylmercury could
increase human susceptibility to infectious disease and increase human susceptibility to infectious disease and
autoimmune disorders by damaging the immune system autoimmune disorders by damaging the immune system

16. Adverse effectsAdverse effects

Reproductive EffectsReproductive Effects

The reproductive effects stemming from methylmercury exposure The reproductive effects stemming from methylmercury exposure
are not fully evaluated yetare not fully evaluated yet

The Great Lakes Human Health Effects Research Program has The Great Lakes Human Health Effects Research Program has
found evidence that suggests:found evidence that suggests:

Conception rate and the incidence of a live birth are lower in some women Conception rate and the incidence of a live birth are lower in some women
who are sport fish consumers who are sport fish consumers

An association was found between men who consumed large amounts of An association was found between men who consumed large amounts of
sport fish and the risk of delayed conception in their spouses. sport fish and the risk of delayed conception in their spouses.

Significant menstrual cycle reductions were indicated in women who Significant menstrual cycle reductions were indicated in women who
reported consuming more than 1 meal per month of contaminated Great reported consuming more than 1 meal per month of contaminated Great
Lakes sport fishLakes sport fish

17. Adverse effectsAdverse effects

Kidney DamageKidney Damage

Organic and inorganic forms of mercury have been shown to Organic and inorganic forms of mercury have been shown to
damage the renal tubules and nephrons of the kidneydamage the renal tubules and nephrons of the kidney

Similar effects were seen in animal studies Similar effects were seen in animal studies

Cardiovascular EffectsCardiovascular Effects

Cardiovascular system appears to be a target to Cardiovascular system appears to be a target to
methylmercury toxicity in both humans and animalsmethylmercury toxicity in both humans and animals

These effects have been shown to occur at very low exposure These effects have been shown to occur at very low exposure
levels traditionally thought of as safe levels traditionally thought of as safe

18. Adverse effectsAdverse effects

Alters blood pressure regulation of both adults and children Alters blood pressure regulation of both adults and children
at varying exposure levels and durationsat varying exposure levels and durations

Men who consumed at least 30 grams of fish a day, or had Men who consumed at least 30 grams of fish a day, or had
hair mercury concentration of less than or equal to 2 ppm hair mercury concentration of less than or equal to 2 ppm
had a higher risk of acute myocardial infarction and increased had a higher risk of acute myocardial infarction and increased
risk of dying from heart diseaserisk of dying from heart disease

20. Methylmercury poisoningMethylmercury poisoning

Iraq (1971):Iraq (1971):

Grain had been treated with methyl mercury Grain had been treated with methyl mercury
compounds as a fungicide and should have been compounds as a fungicide and should have been
plantedplanted

Instead it was sold for milling and made into breadInstead it was sold for milling and made into bread

It had been dyed red as a warning and also had It had been dyed red as a warning and also had
warning labels in English and Spanish that no one warning labels in English and Spanish that no one
could understandcould understand

21. Methylmercury poisoningMethylmercury poisoning

Minimata Bay, JapanMinimata Bay, Japan

Over 3,000 victims have been Over 3,000 victims have been
recognized as having recognized as having
“Minamata Disease”“Minamata Disease”

From 1932 to 1968, _______From 1932 to 1968, _______
CorporationCorporation, a company , a company
located in Kumamoto Japan, located in Kumamoto Japan,
dumped an estimated 27 tons dumped an estimated 27 tons
of mercury compounds into of mercury compounds into
Minamata BayMinamata Bay

22. Methylmercury poisoningMethylmercury poisoning

Thousands of people whose normal diet included fish from the Thousands of people whose normal diet included fish from the
bay, unexpectedly developed symptoms of methyl mercury bay, unexpectedly developed symptoms of methyl mercury
poisoningpoisoning

Minimata DiseaseMinimata Disease: The disease is characterized by peripheral : The disease is characterized by peripheral
sensory loss, tremors, dysarthria, ataxia, and both hearing and sensory loss, tremors, dysarthria, ataxia, and both hearing and
visual lossvisual loss

____________—Speech that is characteristically slurred, slow, ____________—Speech that is characteristically slurred, slow,
and difficult to produce (difficult to understand). Caused by and difficult to produce (difficult to understand). Caused by
paralysis, weakness, or inability to coordinate the muscles of the paralysis, weakness, or inability to coordinate the muscles of the
mouthmouth

23. Methylmercury poisoningMethylmercury poisoning

_________—Wobbliness, incoordination and _________—Wobbliness, incoordination and
unsteadiness due to the brain's failure to (1) regulate the unsteadiness due to the brain's failure to (1) regulate the
body's posture and (2) regulate the strength and body's posture and (2) regulate the strength and
direction of limb movementsdirection of limb movements

Even unborn child at risk from Minamata diseaseEven unborn child at risk from Minamata disease

Methyl mercury readily crosses placenta from mother to fetusMethyl mercury readily crosses placenta from mother to fetus

Children born with Minamata disease can have growth Children born with Minamata disease can have growth
deficiency, _____________ (an abnormally small head), deficiency, _____________ (an abnormally small head),
severe mental retardation and be deaf and blindsevere mental retardation and be deaf and blind

26. Methylmercury Methylmercury

Besides biomethylation by microorganisms, Besides biomethylation by microorganisms, ________________________________
in humans can increase exposure toin humans can increase exposure to [CH [CH
33
Hg]Hg]
++

_______________ is a type of Vitamin B12, and donates methyl _______________ is a type of Vitamin B12, and donates methyl
groups to the myelin sheath that insulates nerve fibers and groups to the myelin sheath that insulates nerve fibers and
regenerates damaged neurons)regenerates damaged neurons)

_______________ can react with less poisonous Hg(II) to _______________ can react with less poisonous Hg(II) to
generate [CHgenerate [CH
33Hg]Hg]
++
an even more poisonous ion an even more poisonous ion