Toxicology I: Air Pollutants

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Author:
klood
ID:
83902
Filename:
Toxicology I: Air Pollutants
Updated:
2011-05-05 01:23:28
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Air Pollutants
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Description:
Air Pollutants - CO, SO2, NOx, Ozone
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  1. What is paracelsus theory?
    • "All substances are poison, there is none which is not a poison. The right does differentiates a poison from a remedy"
    • "Poison" is a quantitative concept!
  2. Define Risk
    The probability or likelihood of adverse effects occuring (toxicity, exp. pop, dose)
  3. Define Risk perception
    • the insight one has to the likelihood of adverse events occuring
    • *Often incorrect
  4. Risk Prevention: 3 step approach
    • 1. Hazard ID and analysis: identify toxins, determine effects & dose response, mechanisms
    • 2. Risk assessment: use data to establish likelihood of exposure and calculate tolerable dose
    • 3. Risk Mgmt: use data to consider technical limits, determine economic costs of prev, propose fed regulations
  5. CO
    • Colorless, odorless, tastless, nonirritating gas
    • Results from incomplete combustion of organic matter
    • MOST ABUNDANT pollutant in lower atm
    • MAJOR CAUSE OF DEATH by poisoning
  6. sources of CO
    • Any inefficient fuel combused w/too little O2
    • Car exhaust, furnaces, gas-powered engines, home water heaters, paint removers containing methylene cl-, smoke from all fires, tobacco smoke
  7. Toxicity of CO
    • Displacement of O2 on Hb, froming carboxyhemoglobin
    • *Affinity of Hb for CO ~220X>than to O2
    • *Dec. O2 carrying capacity of blood, reduced arterial O2 (HYPOXIA)
    • *Altered dissociation characteristics of oxyhemoglobin -> dec O2 release in tissues (CELLULAR ASPHYXIA)
    • -Directly interferes w/cellular respiration by binding to cellular cytochromes in respiratory chain
    • -Binding to myoglobin -> muscle dysfunction
    • -Lipid peroxidation, reperfusion injury
  8. Factors influencing CO toxicity
    • [CO] in air and duration of exp
    • Resp. min volume
    • CO (heart pts at risk)
    • Oxygen demand of tissue (brain and heart)
    • [Hb]
    • Metabolic rate (children @ risk)
  9. CO in pregnancy
    Fetal Hb binds CO more avidly than HbA and fetal levels dec more slowly than in mother
  10. Symptoms of ACUTE CO poisoning
    HEADACHE, dizziness, weakness, nausea, difficulty conc/confusion, SOB, visual changes, chest pain, loss of consciousness
  11. Tx of CO poisoning
    • Fresh air
    • Artificial respiration
    • 100% oxygen - immediately
    • correction of hypotension and acidosis
    • monitor cardiac function
  12. Sources of SO2
    • Fossil Fuel combusion by industry (mostly coal)
    • Wide distribuation by air
  13. Uses of SO2
    Fumigation of fruits and veg, bleaching, tanning, brewing, preserving, refrigeration, by-product of smelting, paper and rubber manufacturing
  14. SO2 -Acute & Long-term effects of toxicity
    • Acute: irritation, cough, burning, lacrimation, difficulty swallowing
    • Long-term: aggravation of COPD; children - reduced lung function, inc URI
  15. SO2 MOA
    • SO2 + moisture (airways) -> sulfurous acid
    • *Irritation, - of mucociliary transport, vagal +, airways smooth muscle constriction (bronchospasm)
    • *Liver detoxifies acid to sulfates
  16. Tx of SO2 toxicity
    Remove from source, immediate support of airway and breathing, decontaminate w/copious irrigation and dilution
  17. Dental effects of SO2 exposure
    Correlated w/ caries, gingivities, periodontal disorders, rapid loss of restorations
  18. NOx Source
    Power plants and cars: catalytic converters reduce ozone, HC, and CO but not NOx
  19. NOx MOA
    • POTENT RESP TRACT TOXIN
    • Not very water soluble -> penetrates DEEP into the lung
    • Decomposes in alveoli to nitrous acid, nitric ace, and NO on contact with moisture
    • May cause lipid perox, DEC CILIARY MOVEMENT, BRONCHOCONSTRICTION, enzyme -
  20. Clinical symptoms of NOx
    bronchitis, pneumonia, hemorrhagic pulmonary edema, alveolar damage
  21. Features of Ozone
    • Bluish gas, no or slightly pungent odor
    • Formed by photochem rxn (NOx cycle)
    • Highly chemically reactive, oxidizing
    • Relatively insoluble -->pen. DEEP into lung
    • W/moisture get formation of OH* (perox of lipids, oxidation of thiols, amines, proteins)
  22. Symptoms of ozone toxicity
    • Acute High Dose: pulmonary edema and hemorrhage
    • Acute Low dose: asthma, mucosal irritation of URT
    • Chronic Exp: chronic bronchitis, emphysema, fibrosis, perm. lung damage

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