4.3 Routes of exposure, poisoning symptoms & first aid

The Four Routes of Exposure

Pesticides can enter the body by four routes, and knowing them shapes both how you protect yourself and how you give first aid.

• Dermal (through the skin) is the most common route of pesticide exposure for applicators. Splashes, spills, drift, and contact with treated surfaces expose the skin. Absorption varies by body region: the skin of the groin, underarms, scalp, forehead, and ear canal absorbs far more than the forearm or palm. ECs and other solvent-based products penetrate the skin especially fast.
• Oral (through the mouth) means swallowing pesticide by eating, drinking, or smoking with contaminated hands, by a splash into the mouth, or through the dangerous practice of clearing a clogged nozzle by mouth.
• Inhalation (through the lungs) means breathing vapors, dusts, or fine spray mists. Fumigants, ULV sprays, and the dust from measuring wettable powders are important inhalation hazards, and the lungs absorb chemicals very efficiently.
• Ocular (through the eyes) means splashes and drift into the eyes; the eye absorbs readily and some corrosive products cause permanent damage.

Recognizing Pesticide Poisoning

Symptoms of poisoning often resemble the flu or heat illness, which is why applicators must connect symptoms to recent pesticide handling. Signs range from mild to life-threatening:

• Mild: headache, fatigue, dizziness, irritated eyes, nose, and throat, skin irritation, excessive sweating, and blurred vision.
• Moderate: nausea, vomiting, diarrhea, excessive salivation, stomach cramps, chest tightness, muscle twitching, weakness, and rapid pulse.
• Severe: inability to breathe, pinpoint pupils, unconsciousness, and convulsions.

Because these symptoms overlap with heat stress, dehydration, and viral illness, treat any sudden illness during or after handling pesticides as possible poisoning until proven otherwise. Note what product was used, the amount, and the time of exposure so a physician can respond quickly. Keep a copy of the label, the EPA registration number, and the poison-control number where handlers can reach them without delay.

Organophosphates and Carbamates

Two insecticide families deserve special attention because they attack the nervous system by inhibiting the enzyme cholinesterase. Organophosphates and carbamates cause cholinesterase inhibition, letting the nerve transmitter acetylcholine build up. Classic signs are headache, nausea, sweating, excessive salivation and tearing, blurred vision, pinpoint (constricted) pupils, muscle twitching, and difficulty breathing. The antidote is atropine (sometimes with pralidoxime, or 2-PAM, for organophosphates), given only by medical personnel. Applicators who handle these products regularly may need periodic cholinesterase blood-level monitoring to establish a baseline and detect over-exposure before symptoms become serious. Carbamate poisoning usually reverses more quickly than organophosphate poisoning, but both are medical emergencies.

Preventing Exposure

The surest treatment is prevention: wear label-required PPE, wash exposed skin promptly, change out of contaminated clothing before breaks, and never eat, drink, or smoke until you have washed. Keep clean water, soap, and a spare set of clothing at the worksite for decontamination. Bathe and launder work clothes separately from family laundry at the end of each day so residues are not spread to others.

First Aid by Route

First aid is the immediate, temporary help given before professional medical care arrives; it is not a substitute for a physician. Always send the label with the victim, because it lists the specific first aid and the antidote for the poison-control center or doctor. General rules by route:

Speed matters. For skin exposure, act quickly because absorption continues every second the chemical stays in contact. For eye exposure, start rinsing immediately with whatever clean water is nearest; speed matters more than volume. For any swallowed pesticide, never give anything by mouth to an unconscious person, and never induce vomiting unless the label directs it, because vomiting a corrosive or petroleum-based product can burn the throat and lungs a second time or be breathed into the lungs.

Always call the national Poison Control Center (1-800-222-1222) or a physician, describe the product from the label, and follow their directions. Keep the victim calm, comfortable, and monitored for breathing until help arrives. When you call for help, be ready to give the product name, the active ingredient, the EPA registration number, the route and time of exposure, and the victim's symptoms and weight. Do not leave a seriously affected victim alone, and be prepared to begin rescue breathing. Knowing the route of exposure lets you deliver the right first aid immediately, and immediate action often makes the difference between a mild exposure and a severe poisoning.