Toxicology I: Air Pollutants

• "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!

The probability or likelihood of adverse effects occuring (toxicity, exp. pop, dose)

• the insight one has to the likelihood of adverse events occuring
• *Often incorrect

• 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

• Colorless, odorless, tastless, nonirritating gas
• Results from incomplete combustion of organic matter
• MOST ABUNDANT pollutant in lower atm
• MAJOR CAUSE OF DEATH by poisoning

• 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

• 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

• [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)

Fetal Hb binds CO more avidly than HbA and fetal levels dec more slowly than in mother

HEADACHE, dizziness, weakness, nausea, difficulty conc/confusion, SOB, visual changes, chest pain, loss of consciousness

• Fresh air
• Artificial respiration
• 100% oxygen - immediately
• correction of hypotension and acidosis
• monitor cardiac function

• Fossil Fuel combusion by industry (mostly coal)
• Wide distribuation by air

Fumigation of fruits and veg, bleaching, tanning, brewing, preserving, refrigeration, by-product of smelting, paper and rubber manufacturing

• Acute: irritation, cough, burning, lacrimation, difficulty swallowing
• Long-term: aggravation of COPD; children - reduced lung function, inc URI

• SO₂ + moisture (airways) -> sulfurous acid
• *Irritation, - of mucociliary transport, vagal +, airways smooth muscle constriction (bronchospasm)
• *Liver detoxifies acid to sulfates

Remove from source, immediate support of airway and breathing, decontaminate w/copious irrigation and dilution

Correlated w/ caries, gingivities, periodontal disorders, rapid loss of restorations

Power plants and cars: catalytic converters reduce ozone, HC, and CO but not NOx

• 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 -

bronchitis, pneumonia, hemorrhagic pulmonary edema, alveolar damage

• 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)

• Acute High Dose: pulmonary edema and hemorrhage
• Acute Low dose: asthma, mucosal irritation of URT
• Chronic Exp: chronic bronchitis, emphysema, fibrosis, perm. lung damage