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Name: Bisma Bashir

ID # 20094704

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Introduction to Mercury.

Sources of Hg emission.

Methylmercury (MeHg) in Ocean.

How does MeHg get into Fishes?

MeHg in Human body.

Symptoms of MeHg contamination & Toxic Limit.

MeHg contamination in Bahrain & other GCC Countries.

Conclusion.

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Naturally occurring element

world.

Various forms:

Elemental mercury.

Inorganic salts of mercury.

Organic mercury.

Uses of Hg:

Agricultural fungicides.

Thermometers.

Blood pressure manometers, etc.

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Natural sources10% of Hg entering atmosphere per

year

Volcanic eruption.

Geothermal activity.

Weathering of mercury-containing rocks.

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Anthropogenic sources30% of Hg

entering atmosphere per year

Burning of coal & Mining.

Oil Refining.

Industrial activities.

Waste from consumer products.

Dental amalgam

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Re-emission & re-mobilization process60% of

Hg entering atmosphere per year.

Forest fire.

Biomass burning.

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Organic form of Hg & a Neurotoxin.

Inorganic Hgorganic MeHg by bacterial action200tonnes

Atmospheric deposition, rivers, and sediments 80tonnes

Resident time11 years

Demethylation240tonnes

Incorporated into food web40tonnespose serious risk to health.

Bahrains water0.18-0.38 g/l of MeHglower than U.Ks water

Oman, U.A.E and Saudi-Arabialess MeHg

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Fishesrich source of

Essential Fatty Acids.

Proteins.

Vitamins.

Minerals.

Fish intakereduces heart diseases

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Tilefish Swordfish KingMackerel

Shark Tuna(fresh orfrozen)

Lobster(northern,American)

Salmon Shrimps

MeanMeHgconcentration(ppm)

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Easily absorbed through the GI tract.

Immediately transferred via blood stream within 3-4 days.

5% in blood & 10% in brain.

Half life60days in human body.

Groups @ risk:

Pregnant women.

Women of child-bearing age.

Children.

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In adults,

Paresthesia (tingling sensation).

Malaise (depression or sickness).

Blurred vision.

Deafness.

Dysarthria (speech disorder).

Ataxia (absolute confusion).

Coma which eventually leads to death

Early symptoms/

non-specific

Increasing exposure

to MeHg symptoms

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In pregnant women,

Effect of high doses of MeHg on fetus,

Mental retardation.

Long-term disabilities.

Blindness.

Even death.

Effect of low doses on fetus,

Delay learning.

Autonomic nervous system problems.

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WHO defined RD0.5 g/kg.

US EPA has set a toxic limithuman fetus to be 0.1 g/kg/day

In small fishes>0.5g/gtoxic.

In large predatory fishes>1g/gtoxic.

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Fishesfavorite food.

Qatargood source of minerals and trace elements.

Arabian Gulf waters

Sardines

good source of omega-3 Fatty acids

BahrainCrab meatrich in high quality proteins and minerals

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0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

HgCon

tent(g/g)

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MeHgtoxic to humans.

Can be transferred from atmosphere to water.

Fishes can be contaminated with MeHg.

Large predatory fishes more prone to contaminationavoid.

Avoid consuming same kind of fish on daily basis.

Fishes in Bahrain are currently safe to consume but in moderation.

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