Organochlorines

Chlorinated pesticides are widely used in agriculture but the most common source or organochlorines is Lindane, used for the treatment of head lice. Acute ingestion or repeated large dermal expose causes neurological toxicity which can lead to seizures and a coma.

Toxic Mechanism:

Most organochlorines act as non-competitive antagonists acting at the chlorine ion channel of GABAa receptors but DDT acts by inhibiting sodium channel closure following depolarisation. Both mechanisms are neuroexcitatory.

Toxicokinetics: 

  • Rapidly absorbed following ingestion.
  • Most are well absorbed across the skin
  • Highly lipid soluble and distribute to fat stores hence repeated occupational exposures is an important source.
  • Undergo hepatic microsomal metabolism prior to urinary excretion
  • Elimination of some organochlorines may take weeks to months

Resuscitation:

  • Potential life threats include:
    • Coma – intubate and ventilate
    • Seizures – IV benzodiazepines incrementally dosed every 5 minutes to effect.
      • Check the patient is not in a dysrhythmia
      • Can be managed with benzodiazepines (varying doses in the textbooks, easy method is 0.1mg/kg IV for lorazepam (max 4mg) / midazolam (max 10mg) / diazepam (max 10mg). Or…
      • Lorazepam 0.1mg/kg max 4mg
      • Diazepam 0.15mg/kg max 10mg
      • Midazolam 0.2mg/kg max 10mg
    • Ventricular dysrhythmias – may respond to IV beta blockers (e.g. metoprolol or esmolol)

Risk Assessment

  • The main dose-related risk assessment comes from Lindane as date is sparse for the other organochlorines.
  • In an adult the estimated lethal ingested dose is 125 mg/kg of Lindane.
  • After ingestion toxicity typically occurs within 1 – 2 hours.
  • In children an ingestion of >50 mg (5ml of 1% solution) can cause symptoms. Excessive topical exposure can cause agitation and seizures.
  • Clinical features: (vomiting, agitation and perioral paraesthisia is classic)
    • Nausea and vomiting (can cause a chemical pneumonitis if aspirated secondary to the hydrocarbon vehicle)
    • Anxiety, agitation and confusion
    • Perioral paraesthesia, fasciculation and myoclonic movements
    • Seizures – usually a short duration but recurrent
    • Cardiac dysrhythmias are a rare complication (hyperaemia and acidosis can sensitise the myocardium to catecholamines).
    • Hepatitis and renal impairment have also been reported following acute ingestion.

Supportive Care

  • Agitation: titrated doses of benzodiazepines are effective e.g. diazepam 2.5 – 5 mg every 5 minutes IV until gentle sedation is achieved
  • If intubated consider FASTHUGSINBED Please

Investigations

  • Screening: 12 lead ECG, BSL, Paracetamol level
  • Specific:
    • EUC, LFTs for hepatic and renal impairment
    • Acid-base status – hyperaemia and acidosis
    • Serial ECGs as increased ventricular ectopics may herald ventricular dysrhythmias
    • Serum and fat organochlorine levels are not readily available and do not assist the clinical management.

Decontamination:

  • Exposed skin should be washed with soap and water
  • If ingested, activated charcoal should only be used post intubation via a nasogastric tube.

Enhanced Elimination

  • Not clinically useful.

Antidote

  • None available.

Disposition

  • Children with potential ingestions should be observed for 4 hours, if asymptomatic they may be safely discharged.
  • Excessive dermal exposure only warrants hospital evaluation if symptoms occur
  • If patients present with symptoms they need to managed and observed in an area capable of managing seizures. Those that develop severe symptoms i.e. recurrent seizures and coma require ICU level care post intubation and ventilation.
  • Patients can be safely discharged once asymptomatic.

References:


toxicology library antidote 700 1

Toxicology Library

DRUGS and TOXICANTS

Dr Neil Long BMBS FACEM FRCEM FRCPC. Emergency Physician at Burnaby Hospital in Vancouver Emergency. Loves the misery of alpine climbing and working in austere environments. Supporter of FOAMed, toxicology, tropical medicine, sim and ultrasound

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