Pesticide Poisoning

Key Features

• Includes organophosphates and carbamates

• Inhibit the enzyme acetylcholinesterase and increase acetylcholine activity at nicotinic and muscarinic receptors and in the peripheral and central nervous systems

• Most are absorbed through intact skin

• Most chemical warfare "nerve agents" (such as GA [tabun], GB [sarin], GD [soman] and VX) are organophosphates

Clinical Findings

• Abdominal cramps

• Diarrhea

• Vomiting

• Excessive salivation

• Sweating

• Seizures

• Lacrimation

• Constricted pupils

• Wheezing

• Bronchorrhea

• Skeletal muscle fasciculations

• Weakness

• Respiratory arrest

• Initial tachycardia may be followed by bradycardia

• Symptoms may persist or recur for days, especially with highly lipid-soluble agents such as fenthion or dimethoate

Diagnosis

• Suspected in patients who present with miosis, sweating, and diarrhea

• Serum and red blood cell cholinesterase activity is usually at least 50% below baseline with severe intoxication

Treatment

• For recent ingestions, consider gut decontamination by aspiration of the liquid using a nasogastric tube followed by administration of activated charcoal

• If the agent is on the victim's skin or hair, wash with soap or shampoo and water

• Care providers should avoid skin exposure by wearing gloves and waterproof aprons

• Dilute hypochlorite solution (eg, household bleach diluted 1:10) is reported to help break down organophosphate pesticides and nerve agents on equipment or clothing

• Administer atropine, 2 mg intravenously, and give repeated doses as needed (may need several hundred milligrams) to dry bronchial secretions and decrease wheezing

• Administer pralidoxime, 1–2 g intravenously, as soon as possible, and give a continuous infusion (200–500 mg/h) as long as there is any evidence of acetylcholine excess

• Pralidoxime is of questionable benefit for carbamate poisoning