Organophosphates and carbamates are groups of related chemicals commonly used as pesticides to control insects.  Some preparations are approved for veterinary use to control fleas and other parasites.  They are commonly formulated as dusts, granules, emulsions, suspensions, or solutions.  Concentrates are often formulated in a petroleum distillate base. 

Clinically, poisonings from organophosphates and carbamates are similar to each other, and results from the inhibition of acetylcholinesterase and the stimulation of muscarinic and nicotinic receptors.  Carbamate toxicity is generally of shorter duration, as its effect on acetylcholinesterase is reversible.

Deaths from these products occur as a result of acute respiratory failure. 

• Paramedics must contact CliniCall (1-833-829-4099) to discuss the case, ideally prior to arrival at scene
• Decontamination requirements can be complex and must be completed prior to moving the patient to the ambulance for treatment.
  • → PR05: Patient Decontamination

• Attempt to identify the name and amount of the substance the patient was exposed to, including the pesticide control number, WHMIS information, or photo of the label.  This can be sent to CliniCall for additional information.
• Health care staff, including paramedics, should wear protective clothing when handling contaminated clothing and grossly contaminated patients.
• Treatment should be directed at decontamination, administration of antidotes where available, and support for oxygenation and ventilation.

• Activated charcoal may be considered in hospital for up to one hour post-ingestion
• High doses of atropine, in conjunction with pralidoxime, may be required in cases of severe organophosphate poisoning

• Organophosphate pesticides include: acephate, azinphos-methyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, fenthion, malathion, methamidophos, naled, phorate, propetamphos, terbufos, tetrachlorvinphos, trichlorfon.
• Carbamates include: bendiocarb, carbaryl, carbofuran, formetanate, methomyl, oxamyl, propoxur.
• Products may be labeled as “systemic” or “contact” – this refers to the action of the pesticide and whether it is taken into plant tissues.  It has no bearing on human toxicity. 
• The onset of symptoms is usually within minutes to hours after exposure.  Symptoms may be delayed in the case of skin exposure.
• Symptoms can be divided into muscarinic effects – miosis, excessive sweating and bronchial secretions, bradycardia, hypotension – and nicotinic effects (mydriasis, tachycardia, fasiculations, muscle weakness and paralysis).  Central nervous system effects can include headache, drowsiness, seizures, and unconsciousness.
  • Muscarinic receptors are predominantely in the parasympathetic nervous system, whereas nicotinic receptors are primarily in the sympathetic nervous system.
• A useful mnemonic for organophosphate toxicity is SLUDGEM/BBB:
  • Salivation
  • Lacrimation
  • Urination
  • Defecation
  • GI upset
  • Emesis
  • Miosis
  • Bronchorrhea
  • Bronchospasm
  • Bradycardia
• The three “Bs” – bronchorrhea, bronchospasm, and bradycardia – are the most common causes of death in organophosphate and carbamate poisoning.

Pesticide Poisoning