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Lecture 5

EESA10H3 Lecture Notes - Lecture 5: Asthma, Cation-Exchange Capacity, Chisso


Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic
Lecture
5

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Lecture 5
Heavy Metals and Human Health
Heavy Metals
- Naturally occurring extracted from the earth’s crust
o Toxic even at LOW concentrations mostly are in the industrial section.
o Wide environmental dispersion
Impacts the water, air, soil enters the food chain ultimately affects humans.
Biomagnification increase accumulation as you go up in the food chain
Bioaccumulation accumulation of one compound/chemical in a tissue
o E.g. Arsenic goes directly into nails and accumulates
- Metals are classified according to toxicity and importance to the biological system:
o Class B > Borderline > Class A
o Class A
Essential for biological processes
Macronutrients animals need these in their bodies
Very low toxicity
Form ionic bonds (attraction between positive and negative ions)
E.g. K, Na, Mg, Ca
o Class B
Not important for biological processes
Very toxic in ANY form
E.g. Mercury is toxic in its organic and inorganic form
Form covalent bonds (two ions share electrons very strong bond)
They are also organometallics complexes between metals and organic
compounds
In addition to this, they are also soluble when they enter the body that’s
why they are very toxic
Eg. Hg, Ti, Pb, Ag, Au
o Borderline
Important for biological processes in very LOW concentrations (as opposed to
macronutrients)
Micronutrients
Eg. Arsenic (As)
Belongs to the borderline group
o It’s not essential and not even a metal but belongs here because of
its toxicity.
Eg. Cr, Fe, Co, Ni, Cu, Zn, Mn
- Mechanism of Toxicity
o Metals can:
Block functional groups such as proteins and enzymes so proteins cannot
carry anything
Displace other metals
Non-essential ones can replace the essential metals in our bodymostly
Class B’s and borderlines
Change/modify the conformation of biomolecules Class B
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