10.4 Symptoms of Pesticide Poisoning, First Aid, and Emergency Procedures

10.4 Symptoms of Pesticide Poisoning, First Aid, and Emergency Procedures

Acute vs. Chronic Toxicity

Pesticides are chemical tools designed to disrupt biological processes. While they target pests, they can also cause adverse health effects in humans. The toxic effects of pesticides are categorized based on the duration of exposure and the speed of symptom onset:

• Acute Toxicity: This refers to the rapid onset of adverse health effects following a single, high-dose exposure to a pesticide. Symptoms typically manifest within minutes to hours after contact. Examples include skin burns from acid-based wood preservatives, immediate dizziness and headache from inhaling solvent vapors, or systemic poisoning from swallowing a pesticide concentrate. The severity of acute toxicity is reflected in the product's signal word on the label (DANGER, WARNING, or CAUTION).
• Chronic Toxicity: This refers to adverse health effects that develop over a long period from repeated, low-dose exposures. Chronic effects are often delayed, manifesting months or years after the initial exposure. Examples of chronic toxicity include cancer (oncogenicity), birth defects (teratogenicity), reproductive dysfunction, organ damage (kidney, liver, or lungs), and progressive neurological disorders. In structural pest control, technicians are at a high risk for chronic toxicity if they consistently neglect daily PPE requirements or practice poor personal hygiene, leading to a slow, cumulative buildup of chemical residues in their bodies.

Symptoms of Pesticide Poisoning

Recognizing the symptoms of pesticide poisoning is a critical safety skill for pest control technicians. Symptoms vary depending on the chemical class, but the most severe occupational poisoning hazards in structural pest control are associated with organophosphate and carbamate insecticides. These chemicals act as nervous system toxins, and their poisoning symptoms are generally categorized by severity:

• Mild Poisoning: Early symptoms include a persistent headache, fatigue, dizziness, mild nausea, irritation of the throat and skin, and excessive sweating. These symptoms are often mistaken for flu or heat exhaustion.
• Moderate Poisoning: As exposure increases, the victim may experience persistent vomiting, abdominal cramps, diarrhea, excessive salivation (drooling), muscle tremors, blurred vision, and chest tightness.
• Severe Poisoning: Severe poisoning is a life-threatening emergency. Classic symptoms include pinpoint pupils (miosis), uncontrollable muscle twitching (fasciculations), rapid and shallow breathing, convulsions, loss of consciousness, coma, and ultimately death from respiratory failure.

It is vital to distinguish pesticide poisoning from heat stroke. While both cause headaches, dizziness, and confusion, a heat stroke victim will have hot, dry, red skin and dilated (large) pupils, whereas an organophosphate/carbamate poisoning victim will exhibit cold, clammy skin, excessive sweating, and pinpoint (very small) pupils.

Immediate First Aid Protocols

If exposure occurs, immediate first aid can save lives and reduce the severity of injury. First aid is temporary treatment and must be followed by professional medical evaluation. Technicians must react according to the route of exposure:

• Dermal Exposure: Speed is critical. Immediately strip off all contaminated clothing and shoes. Wash the skin thoroughly with copious amounts of cool water and non-abrasive soap. Do not scrub the skin harshly with brushes, as this can scratch the epidermis and accelerate pesticide absorption. Wrap the victim in clean blankets or clothing to prevent shock.
• Ocular Exposure: Flush the eyes immediately with a gentle stream of clean water or an eyewash station. Hold the eyelids open wide and flush continuously for at least 15 to 20 minutes to rinse away all chemical residue. Always flush from the nose outward to avoid washing contaminated water into the unaffected eye. Do not add any eye drops or neutralizing agents to the water.
• Inhalation Exposure: Move the victim to fresh air immediately. Loosen tight clothing around the neck and waist. Keep the victim warm and quiet. If the victim is not breathing, perform cardiopulmonary resuscitation (CPR) using a pocket mask or barrier device to avoid exposing yourself to chemical vapors in the victim's lungs.
• Ingestion Exposure: Immediately read the pesticide label for specific instructions. Do not induce vomiting unless the label or a medical professional explicitly directs you to do so. Many structural pesticides are formulated with petroleum-distillate solvents. If vomiting is induced, these solvents can easily be aspirated (breathed) into the lungs, causing severe, life-threatening chemical pneumonia. If vomiting is required, place the victim on their side or face-down to prevent aspiration.

Cholinesterase Monitoring for Organophosphates and Carbamates

Organophosphate and carbamate insecticides are powerful acetylcholinesterase (AChE) inhibitors. In the nervous system, acetylcholine is a neurotransmitter that transmits signals across nerve junctions. Once the signal is sent, the cholinesterase enzyme breaks down acetylcholine to allow the muscle or nerve to relax. Organophosphates and carbamates bind to the cholinesterase enzyme, blocking its activity. This causes acetylcholine to accumulate, leading to continuous, uncontrolled firing of the nervous system and muscles.

To protect workers from cumulative exposure to these chemicals, California Title 3, CCR Section 6728 establishes a mandatory Cholinesterase Monitoring Program. Employers must provide medical monitoring to employees who mix, load, or apply organophosphate or carbamate pesticides containing the signal words "DANGER" or "WARNING" for more than 6 days in any 30-day period.

The program consists of:

1. Baseline Blood Test: A blood sample is taken before the employee begins handling these chemicals (usually after at least 30 days of no exposure). This establishes their normal, healthy cholinesterase level.
2. Periodic Blood Tests: Blood samples are taken at regular intervals (typically every 3 to 4 weeks) while the employee handles these chemicals to measure their active cholinesterase levels.
3. Action Thresholds: If an employee’s cholinesterase level drops below their baseline, specific actions must be taken:
   • 20% to 30% Drop: The employer must investigate the employee’s work practices, equipment, and PPE usage to identify and correct the source of exposure.
   • 40% to 50% Drop: The employer must immediately remove the employee from all duties involving exposure to organophosphates or carbamates. The employee cannot return to these duties until their blood cholinesterase levels recover to within 80% of their baseline.