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Types of Poisons and Their Effects on the Human Body

A poison is any substance that causes harm to living tissue by altering physiological processes. Toxicity depends on dose, route, duration, and individual susceptibility. Below are major categories with representative examples.

Major Classes of Poisons

1. Heavy Metals

MetalSourcesKey Effects
ArsenicContaminated water, pesticides, wood preservativesGI (vomiting, rice-water stool), neuropathy, skin lesions, cancer
LeadPaint (pre-1978), pipes, batteries, ceramicsNeurodevelopmental (children), anemia, neuropathy, renal, CV
MercuryFish (methylmercury), amalgam, thermometersNeuro (tremor, memory), renal, dermatitis (acrodynia)
CadmiumBatteries, plating, smokeRenal (Fanconi), osteomalacia (itai-itai), lung cancer

2. Cyanide

  • Mechanism: Binds cytochrome c oxidase (Complex IV) → blocks cellular respiration.
  • Sources: Smoke inhalation, industrial, amygdalin (apricot kernels), sodium/potassium cyanide.
  • Presentation: Sudden collapse, seizures, coma, cherry-red skin (late), bitter almond odor.
  • Antidotes: Hydroxocobalamin (Cyanokit), nitrites + thiosulfate kit.

3. Pesticides

  • Organophosphates/Carbamates: Acetylcholinesterase inhibition → cholinergic crisis (SLUDGE: salivation, lacrimation, urination, defecation, GI upset, emesis). Atropine + pralidoxime.
  • Organochlorines (DDT): Neurotoxic, endocrine disruptor, persistent.
  • Pyrethroids: Lower mammalian toxicity; paresthesia, asthma trigger.

4. Envenomations

  • Snake venom: Hemotoxic (viperids: coagulopathy, necrosis), neurotoxic (elapids: paralysis), cytotoxic. Antivenom specific.
  • Spider (widow, recluse), scorpion, marine (stonefish, cone snail).

5. Drugs and Chemicals

  • Carbon monoxide (CO): Binds Hb → tissue hypoxia. Headache, confusion, cherry-red. 100% O2, HBO.
  • Methanol/Ethylene glycol: Metabolic acidosis, end-organ toxicity. Fomepizole, ethanol, dialysis.
  • Corrosives (acids/alkalis): Tissue liquefaction/coagulation necrosis. No emesis; dilute, endoscopy.

6. Biological Toxins

  • Botulinum toxin: Flaccid paralysis. Antitoxin.
  • Mycotoxins (aflatoxin): Hepatotoxic, carcinogenic.
  • Algal blooms (saxitoxin, microcystin).

General Principles of Poison Management

  1. Scene safety / PPE
  2. ABCs – Airway, Breathing, Circulation
  3. Identify toxin – History, containers, toxidrome recognition
  4. Decontamination – Ocular, dermal, GI (activated charcoal if appropriate)
  5. Antidotes – Specific, timely
  6. Enhanced elimination – Dialysis, hemoperfusion, alkalinization
  7. Supportive care – Ventilation, hemodynamics, seizures
  8. Poison Control: 1-800-222-1222 (US) – expert guidance 24/7

Poisoning is a medical emergency. Early recognition and specific intervention save lives.

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