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Toxicology of Hazardous Chemicals

Toxicology of Hazardous Chemicals. By Jack Hay 3/2/06. Introduction. 627,000 toxic chemicals/compounds More than 600 new added annually 1.5 billion tons shipped per year 500,000 shipments daily 24,359 hazardous chemical accidents 1993-1997. Epidemiology.

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Toxicology of Hazardous Chemicals

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  1. Toxicology of Hazardous Chemicals By Jack Hay 3/2/06

  2. Introduction • 627,000 toxic chemicals/compounds • More than 600 new added annually • 1.5 billion tons shipped per year • 500,000 shipments daily • 24,359 hazardous chemical accidents 1993-1997

  3. Epidemiology • 10-30% of hazardous accidents have victims • Trauma most common • Non-traumatic injuries • Respiratory & eye irritation • Nausea/vomiting • Headache, dizziness, other neurological effects • Unknown toxins 25% of cases

  4. Fatalities • Trauma (65%) • Burns (22%) • Respiratory compromise (10%) • Common toxins • Chlorine, ammonia, nitrogen, fertilizer, hydrochloric acid

  5. Nerve Agents (Organophosphates) • Most toxic chemical threats known • Liquids with distinct odors • Tabun (fruity) • Soman (fruity/camphorous) • Sarin & VX (odorless) • Powerful AChE inhibitors

  6. Nerve Agents • Acetylcholine accumulation • Initial fasciculations • Progress to weakness and paralysis • Tachycardia and hypertension • Miosis, lacrimation, salivation • Bronchorrhea, bronchospasm • Vomiting, diarrhea, excess urination

  7. Nerve Agents • Onset & type of reaction based on both concentration & route of exposure • High risk of secondary contamination • Wear skin & respiratory protection • Surgical and HEPA masks are inadequate • Cleanse with soap & water

  8. Nerve Agents • Oxygenation is next most critical step • Oxines, ex. 2-PAM (pralidoxine chloride) • Reactivates AChE • Atropine • Blocks muscarinic receptors • End-point for dosing is drying of pulmonary secretions

  9. Nerve Agents • Cardiac monitoring for dysrhythmias • Seizure precautions • Ventilatory support • 23 hour observation for • Symptomatic patients • Dermal exposure

  10. Vesicants • Blistering liquid agents • Low dose  vesication • Erythema progressing to blister formation • High dose  systemic toxicity • Corneal ulcers, ocular edema/irritation • Cough, hoarseness, bronchospasm • Hematopoietic, GI, CNS (massive exposure)

  11. Mustard (H, HS, HD) • Not the kind that goes on a hot dog • Oily liquid with odor of mustard, garlic, or horseradish • Alkylating agents attacks peptides, proteins, DNA, RNA, cell membranes

  12. Mustard • Median lethal dose of 1.5 teaspoon  25% BSA burn • Symptoms delayed 4-8 hours • Urinary thiodiglycol metabolites confirm exposure • Not available at South Pointe Hospital

  13. Mustard • Water irrigation – skin, eyes and hot dog • Supportive care • Airway, fluids, electrolytes, analgesics • Send patient to burn center

  14. Lewisite (L) • Oily odorless liquid • Trivalent arsenic inhibits enzymes and interferes with glycolysis • Initial symptoms within 15-30 minutes • Greater tissue destruction than with mustard • Rarely pulmonary edema

  15. Lewisite • Water irrigation & supportive care • Burn center transfer • British anti-Lewisite (BAL, dimercaprol) • Arsenic chelator • Apply topically within MINUTES of exposure • Can later be given IM

  16. Respiratory Agents • Watch for steam/smoke inhalation injuries • 100% oxygen • Humidification for irritative symptoms • Inhaled bronchodilators for spasm • Early intubation for upper airway edema • CXR, lactate level, ECG monitoring & ABG with carboxyHb, methHb

  17. Phosgene (CX) • White gas with odor or newly mown hay • Instantaneous skin pain/irritation • Deep necrosis/ eschar formation • No vesicle formation

  18. Phosgene • Initially mild upper airwar irritation • Later acid burns lower airway • Pulmonary edema results from alveolar leak • Usually delayed up to 24 hours • Onset within 4 hours is very poor prognosis

  19. Phosgene • Irrigate with water ONLY • Supportive care • Burn center transfer • A least 24 hour observation even if asymptomatic • Recovery occurs in 3-4 days

  20. Chlorine • Acrid, pungent, yellow-green gas • Forms acids and oxidants on moist membranes • Immediate ocular/upper airway irritation • Nausea/vomiting common in mild exposure

  21. Chlorine • Significant exposure • Cough progresses to pulmonary edema within 24 hours • Permanent reactive airway disease • Treatment is supportive • Humidified oxygen and bronchodilators • Nebulized NaHCO3 is controversial

  22. Nitrogen Oxide • Result of blasts, obscurants, combustion • Triphasic illness • Initially flu-like with dyspnea • Transient improvement • Dyspnea worsens with edema 24-72 hours after exposure

  23. Nitrogen Oxide • Give prophylactic steroids with antibiotics • Prevents bronchiolitis obliterans • Supportive treatment • Humidified oxygen and bronchodilators

  24. Ammonia • Colorless, pungent, alkaline corrosive gas • Immediate induction of symptoms • Eye, mucous membranes & throat irritation • Anhydrous ammonia penetrates anterior chamber within 1 minute of exposure

  25. Ammonia • Lower airway involvement • Bronchospasm  edema • Residual reactive airway disease • Supportive treatment • Humidified oxygen and bronchodilators • Ocular irrigation if asymptomatic • Evaluate for corneal burns

  26. Metabolic Toxins • Cyanide • We’ll have an exciting and thorough discussion in about 10 minutes… • Hydrogen sulfide • Ricin • Industrial toxins

  27. Hydrogen Sulfide • Colorless & flammable • Disrupts oxidative phosphorylation • Respiratory & ocular irritation • LOC, seizures & death in only a few seconds in high concentrations

  28. Hydrogen Sulfide • Treat with decontamination, oxygen and hyperbaric chamber • Use Nitrite component of cyanide antidote kit • Converts sulfide to sulfmethHb

  29. Ricin • Ribosome inhibiting protein found in castor bean processing • Mist, powder or pellets dissolve in water or weak acids • Unaffected by heat or cold (extremely stable) • 500 mcg injection can cause death

  30. Ricin • Injected  multi-organ failure (MOF) and coagulopathies lead to death • Ingested  MOF & GI hemorrhage • Inhaled  resp distress & pulmonary edema • No lab test for diagnosis • Supportive treatment

  31. Misc. Industrial Toxins • Aniline or nitrite derivatives • RBC oxidant stress • Chlorates, benzene, acetaniid, nitrophenols, phenols, sulfonamides, para-toluene • Supportive treatment

  32. Hydrocarbons • Sensitizes myocardium to the dysrhythmic effects of catecholamines • Early mental stimulation followed by confusion, coma lethargy, stupor or coma • Avoid physical activity or sympathomimetics except selective for b2 bronchospasm

  33. Riot Control Agents • Mace and Capsaicin • Transient (few hours) but intensely noxious • Fatalities from pulmonary edema in enclosed space • Irritation of eyes, skin and respiratory tract • May have nausea/ vomiting

  34. Riot Control Agents • Copiously irrigate eyes with normal saline • Wash skin with soap and water • Do not use bleach • With pre-existing lung disease… • Treat for bronchospasm • Admit for observation

  35. Incapacitating Agents • Not lethal • Take hours to days to recover completely • 3-quinuclidinyl benzilate (BZ) • Anticholinergic deliriant • Resembles atropine • Supportive treatment • Benzodiazepines prevent hyperthermia and rhabdomyolysis

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