3.4 Poisoning Symptoms and Emergency Response

Why Symptoms Matter

Iowa Administrative Code Rule 21-45.22(8) requires certified handlers to demonstrate knowledge of poisoning symptoms. Recognition is the first link in the emergency chain: the sooner symptoms are identified, the sooner decontamination and medical care can begin.

Cholinesterase-Inhibiting Pesticides

Organophosphate (OP) and carbamate insecticides inhibit the enzyme acetylcholinesterase, which normally breaks down the neurotransmitter acetylcholine. When acetylcholine accumulates, nerves overstimulate muscles and glands. The result is the classic cholinergic toxidrome.

Muscarinic Effects - the SLUD Mnemonic

• Salivation
• Lacrimation (tearing)
• Urination
• Defecation (diarrhea)

Add the 'GEM' extension for a fuller picture:

• GI upset and Emesis (vomiting)
• Miosis (pinpoint pupils)

Other muscarinic signs include bronchorrhea (excess lung secretions), bronchospasm, and bradycardia (slow heart rate). The patient may literally drown in their own secretions, which is why respiratory support is critical.

Nicotinic and CNS Effects

• Nicotinic: muscle fasciculations (twitching), weakness, cramps, tachycardia, sweating.
• CNS: headache, dizziness, drowsiness, confusion, seizures, coma.

Organophosphates bind cholinesterase irreversibly; the bond 'ages' over hours and then cannot be broken. Carbamates bind reversibly, and symptoms usually resolve within 24 to 48 hours, but the acute presentation can be just as severe.

Other Common Pesticide Symptom Patterns

Recognizing Mild vs. Severe Poisoning

Mild or early OP/carbamate exposure may show only headache, dizziness, nausea, sweating, and mild weakness - symptoms easily mistaken for heat fatigue or a stomach bug. As exposure increases, the full SLUD picture emerges with profuse secretions, muscle twitching, difficulty breathing, and pinpoint pupils. Severe poisoning brings bronchospasm, seizures, coma, and respiratory failure.

The pace of progression depends on the dose, the route, and the formulation. Concentrated dermal contact with a lipophilic OP can delay peak symptoms for several hours, while inhalation of a fumigant can collapse an applicator in minutes. Absorption through sweaty skin in hot, humid weather accelerates onset. Anyone who works regularly with OP or carbamate insecticides should consider a baseline blood cholinesterase test and periodic retesting through a physician, because depressed cholinesterase levels flag overexposure before symptoms become dangerous. Iowa occupational-health resources and the applicator's employer can help arrange this surveillance.

What the SDS Tells the Medical Provider

The Safety Data Sheet (SDS) for the product carries far more treatment detail than the label. The most important sections to point out to the medical provider are:

• Section 2 - hazard identification and signal word.
• Section 4 - first-aid measures specific to the active ingredient.
• Section 5 - fire-fighting measures (relevant if the exposure involved a fire).
• Section 9 - physical and chemical properties (flash point, vapor pressure).
• Section 11 - toxicological information, including cholinesterase inhibition potential.
• Section 12 - ecological information, important if the spill reached water.

If the SDS is not on hand, call the registrant. The EPA registration number on the label identifies the manufacturer, and Poison Control (1-800-222-1222) can often retrieve the SDS and guide treatment over the phone.

First Aid Steps at the Scene

1. Protect yourself first. Do not become the second victim. Wear chemical-resistant gloves before touching the victim's contaminated clothing.
2. Get the victim away from the source. Move upwind and out of the treated area.
3. Decontaminate. Remove contaminated clothing immediately; flush skin and hair with copious water and soap for at least 15 minutes. For eye exposure, irrigate with clean water for 15 minutes, holding eyelids open.
4. Check airway and breathing. Provide CPR if trained and indicated.
5. Call Poison Control at 1-800-222-1222 for expert guidance. In Iowa this connects to the Iowa Poison Control Center.
6. Get the label and SDS. Take them to the medical facility; treatment depends on the active ingredient.
7. Do not induce vomiting unless the label or Poison Control specifically directs it. Some hydrocarbon solvents cause aspiration pneumonia if vomited.

Medical Treatment Overview

• Atropine is the antidote for muscarinic symptoms of OP and carbamate poisoning. It is titrated until secretions dry and bronchospasm clears; severe cases may require hundreds of milligrams.
• Pralidoxime (2-PAM) reactivates cholinesterase for organophosphate poisoning and helps with nicotinic effects. It must be given before the enzyme ages, and it is always given after atropine to avoid worsening muscarinic symptoms. It is generally not used for carbamate poisoning.
• Supportive care - airway, oxygen, IV fluids, seizure control with benzodiazepines, and ICU monitoring for 48 hours or more.

Heat Stress vs. Pesticide Poisoning

On a hot Iowa summer day, heat stress and pesticide poisoning can look alike: nausea, headache, dizziness, weakness, and even collapse. Distinguishing them is critical.

When in doubt, decontaminate first, then treat for both heat and pesticide exposure, and call Poison Control. A misdiagnosed OP exposure can be fatal within hours.