ENSC 201 Lecture Notes - Lecture 8: Lake Huron, Carcinogen, Lead Poisoning
10 Mar 2017
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Document Summary
Metals such as zinc (zn), cadmium (cd), mercury (hg), lead (pb), etc. The term heavy metal is vague, often misused and should be avoided - don"t use it. Millions of people exposed to toxic levels of arsenic in drinking water, from a natural source. Some metals or inorganic elements may be essential for good health, some are toxic above certain concentrations, and some are both. Zinc: essential at low concentrations, but generally non-toxic for humans. Lead: considered toxic to humans, possibly even at very low concentrations. Selenium, fluorine: essential at low concentrations, toxic at high concentrations. Canadian soil quality guideline is 200 mg/kg (based on toxicity data) Soil developed over the rocks may also be high in metals, plants may uptake metals, making a pathway of exposure. Canadian drinking water guideline is 5000 ug/l. Metal mine effluent regulations is 500 ug/l. Humans are more tolerant of zinc than fish. Mining involves crushing rocks and exposing them to oxygen and water.
