Pesticide Exposure

Pesticide Exposure - Chemical Culprits

• Organophosphates (OPs):
  • E.g., Malathion, Parathion, Chlorpyrifos.
  • Irreversible acetylcholinesterase (AChE) inhibition.
• Carbamates:
  • E.g., Carbaryl, Propoxur, Aldicarb.
  • Reversible AChE inhibition.
• Organochlorines (OCs):
  • E.g., DDT, Endosulfan, Lindane.
  • Neurotoxic: Na+/K+ channel interference, GABA antagonism. Persistent.
• Pyrethroids:
  • E.g., Permethrin, Cypermethrin.
  • Sodium channel modulators. Relatively low human toxicity.

⭐ Organophosphate compounds (e.g., Phorate - "Thimet", "Sulphas") are a leading cause of fatal poisoning in agricultural communities.

Pesticide Exposure - Tiny Targets

• Children uniquely vulnerable: ↑ exposure, ↓ detoxification.
• Routes: Ingestion (hand-to-mouth, diet), inhalation, dermal.
• Why vulnerable?
  • ↑ Surface area to mass ratio.
  • Immature metabolic pathways (liver).
  • Developing nervous system.
  • Higher intake per kg body weight.
  • Behaviors: crawling, mouthing objects.

⭐ Chronic low-level pesticide exposure in children is linked to neurodevelopmental issues, ADHD, and lower IQ.

Pesticide Exposure - Body's Battle

• Organophosphates (OPs) & Carbamates:
  • Mechanism: AChE inhibition → ↑ACh.
  • Cholinergic Crisis:
    • Muscarinic: 📌 DUMBELS (Diarrhea, Urination, Miosis, Bronchorrhea/Bronchospasm, Emesis, Lacrimation, Salivation).
    • Nicotinic: Fasciculations, weakness, paralysis, HTN, tachycardia.
    • CNS: Seizures, coma.
• Organochlorines (e.g., DDT):
  • Mechanism: CNS stimulant (Na+/K+ ATPase, GABA).
  • Effects: Tremors, seizures, paresthesias.
• Pyrethroids (e.g., Permethrin):
  • Mechanism: Na+ channel modulation.
  • Effects: Paresthesias (skin), dizziness.

⭐ In OP poisoning, Pralidoxime (PAM) reactivates AChE (muscarinic & nicotinic effects), unlike atropine (muscarinic only). Give within 24-48 hrs.

Pesticide Exposure - Silent Sabotage

• Children: ↑ vulnerability (↑intake/kg, immature detox).
• Sources: Food, water, household, parental occupation.
• Types: Organophosphates (OPs), Carbamates, Organochlorines, Pyrethroids.
• Acute OP/Carbamate:
  • Cholinergic crisis: 📌 DUMBELS (Diarrhea, Urination, Miosis, Bradycardia/Bronchospasm, Emesis, Lacrimation, Salivation).
  • Dx: ↓Cholinesterase.
  • Rx: Atropine, Pralidoxime (OPs).
• Chronic: Neurodevelopmental (ADHD, ↓IQ), endocrine, cancer.
• Prevention: Wash food, safe storage, IPM.

⭐ OPs & Carbamates cause cholinergic crisis by inhibiting acetylcholinesterase. Pralidoxime (PAM) is used for OP poisoning (not Carbamates) to reactivate enzyme, ideally within 24-48 hrs.

Pesticide Exposure - Spot & Stop

• Spotting (Toxidromes):

  • Organophosphates (OP) & Carbamates: Cholinergic crisis (📌 DUMBELS: Diarrhea, Urination, Miosis, Bronchospasm/Bradycardia, Emesis, Lacrimation, Salivation). Key: ↓RBC Acetylcholinesterase.
  • Organochlorines (OC): CNS hyperexcitability, tremors, seizures.
  • Pyrethroids: Allergic reactions (skin, respiratory), paresthesias (e.g., facial).
  • Paraquat: Caustic oral/GI injury → progressive pulmonary fibrosis, renal & hepatic failure.

• Stopping Priorities:

  • ABCs: (Airway, Breathing, Circulation).
  • Decontamination: Remove clothes, wash skin (soap & water). Gastric lavage (<1-2h), charcoal.
  • Antidotes:
    • OP: Atropine (muscarinic) + Pralidoxime (PAM, AChE reactivator, 24-48h).
    • Carbamates: Atropine. (PAM generally not indicated).
    • OC: Diazepam for seizures.
    • Paraquat: Supportive; antioxidants (NAC), early hemoperfusion.

• Prevention: Safe handling/storage, Personal Protective Equipment (PPE).

⭐ In Organophosphate poisoning, "aging" refers to the irreversible binding of the phosphate to cholinesterase; Pralidoxime must be given before this occurs, typically within 24-48 hours, to be effective.

High‑Yield Points - ⚡ Biggest Takeaways

• Organophosphates (OPs) & carbamates inhibit acetylcholinesterase (AChE), causing cholinergic crisis (DUMBELS/SLUDGE).
• Key features: Miosis, bradycardia, muscle fasciculations/weakness, seizures.
• Children are highly vulnerable due to greater exposure and immature detoxification.
• Treatment: Decontamination, atropine (muscarinic antagonist), pralidoxime (PAM) for OPs (crucial early).
• Chronic exposure is linked to neurodevelopmental problems (e.g., ADHD).
• Pyrethroids cause paresthesias, allergic reactions; manage symptomatically.
• ↓ RBC AChE levels confirm OP/carbamate poisoning.