Class Notes (839,150)
Canada (511,218)
PHAR 100 (175)
Lecture

20environmentaltoxicants.pdf

6 Pages
64 Views

Department
Pharmacology and Toxicology
Course Code
PHAR 100
Professor
Hisham Elbatarny

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Description
Environmental Toxicants - Part 1 Acute versus Chronic Toxicity Acute toxicity • single exposure • often large dose ◦ e.g. chemical spill Chronic toxicity • repeated exposure • prolonged time period • small doses ◦ e.g. eating contaminated food Acute toxicity • usually more obvious effects • acute effects often different from chronic effects ◦ e.g. aflatoxin B1 (common food contaminant) ▪ acute: liver necrosis, liver failure, death ▪ chronic: liver cancer Air Pollutants • 1273 – first antipollution law • early 20th century – automobiles • 1952 – “killer smog” in London, England ◦ dense fog + smoke, SO2, particulates ◦ 4,000 deaths ◦ bronchitis, pneumonia, etc. ◦ demonstrated the lethality of air pollution • 1956 – Clean AirAct Major Air Pollutants • gaseous: carbon monoxide (CO), hydrocarbons, hydrogen sulfide, nitrogen oxides, ozone, sulfur oxides, carbon dioxide (CO ) 2 • particulate matter: mixture of tiny particles that are composed of organic, inorganic and biological materials; solids, liquid droplets Sources of Air Pollutants Natural • volcanoes • forest and prairie fires • dust storms • trees, plants Human-Made • anthropogenic: of, relating to, or resulting from the influence of human beings on nature • three main sources Anthropogenic Air Pollutants 1. Combustion of fossil fuels (heating and power) • coal, oil: contain sulfur, sulfur oxides released, acid rain • nitrogen oxides • carbon monoxide (CO): incomplete combustion ◦ efficient combustion: high CO /CO 2 2. Automobile Exhaust • smoke, lead particles, CO, nitrogen oxides, hydrocarbons • late 20th century → decrease emissions 3. Industrial Processes • acids, solvents, metals, etc. Human Health Effects from Air Pollutants • chemical irritation of respiratory tract • particularly susceptible: ◦ very young children ◦ elderly ◦ people with cardiorespiratory diseases ▪ asthma, emphysema, heart disease • most cases: particulates and sulfur oxides responsible Tobacco Smoke: History • tobacco - dried leaves of plant Nicotiana tabacum • Western world introduced in late 15th century • mid 20th century advertising concentrated on social advantages of smoking particular brands • 1964 – U.S. Public Health Service released comprehensive report detailing adverse effects of cigarette smoking Tobacco Smoke: History • 1990’s: Tobacco taxation and smuggling “hot” political issues ◦ successful law suits against manufacturers • 1997: Creation of the TobaccoAct • today: ◦ at least nine provinces suing major tobacco companies ◦ Oct 16th 2012, smoking bylaw in Kingston Tobacco Smoke: Effects on Human Health • adverse effects due to nicotine, CO, tar • > 45,000 deaths/year attributable to smoking in Canada • cigarette smoking causes ~ 30% of all cancers (Canadian Cancer Society) ◦ more than 4000 chemicals in cigarette smoke, at least 60 are known carcinogens ◦ main increased risk is lung cancer ◦ mouth, esophagus, bladder, pancreas, etc. Tobacco Smoke: Cardiovascular Effects • ↑ platelet activation (clotting) • damage to blood vessel lining • changes in lipoproteins (↑ LDL, ↓ HDL) • nicotine effects (see nicotine lecture) • CO: ↓ O t2 tissues, including heart ◦ heart’s O supply/demand affected 2 Tobacco Smoke: Cardiovascular Effects • CoronaryArtery Disease: ↑ risk of heart attack • Cerebrovascular Disease: ↑ risk of stroke due to clot or bleeding • Peripheral Vascular Disease: ↓ blood flow to extremities Tobacco Smoke: Chronic Obstructive Pulmonary Disease (COPD) • Smoking ◦ tar content ↑ action of inflammatory cells ◦ direct chemical damage • Chronic Bronchitis ◦ airways ◦ persistent cough • Emphysema ◦ tissue destruction in peripheral lung ◦ breathl
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