The properties that make insecticides deadly to insects can sometimes make them poisonous to humans. Most serious insecticide poisonings result from the organophosphate and carbamate types of insecticides, particularly when used in suicide attempts. Examples of organophosphates include malathion, parathion, fenthion, dursban, diazinon, chlorpyrifos, and sarin. Some of these compounds are derived from nerve gases. Examples of carbamates include aldicarb, carbaryl, carbofuran, fenobucarb, and oxamyl. Pyrethrins and pyrethroids, which are other commonly used insecticides, are derived from flowers and usually are not poisonous to humans.
Many insecticides can cause poisoning after being swallowed, inhaled, or absorbed through the skin. Some insecticides are odorless, thus the person is unaware of being exposed to them. Organophosphate and carbamate insecticides make certain nerves “fire” erratically, causing many organs to become overactive and eventually to stop functioning. Pyrethrins can occasionally cause allergic reactions. Pyrethroids rarely cause any problems.
Organophosphates and carbamates cause eye tearing, blurred vision, salivation, sweating, coughing, vomiting, and frequent bowel movements and urination. Blood pressure can decrease. Heart rate can decrease and become erratic and seizures can occur. Breathing may become difficult, and muscles twitch and become weak. Rarely, shortness of breath or muscle weakness is fatal. Symptoms last hours to days after exposure to carbamates, but weakness can last for weeks after exposure to organophosphates.
Pyrethrins can cause sneezing, eye tearing, coughing, and occasional difficulty breathing. Severe symptoms rarely develop.
Diagnosis and Treatment
The diagnosis of insecticide poisoning is based on the symptoms and on a description of the events surrounding the poisoning. Blood tests can confirm organophosphate or carbamate poisoning.
If an insecticide might have contacted the skin, clothing is removed and the skin is washed. Anyone with symptoms of organophosphate poisoning should see a doctor. Atropine, given by vein, can relieve most of the symptoms. Pralidoxime, given by vein, can speed up recovery of nerve function, eliminating the cause of the symptoms. Symptoms of carbamate poisoning also are relieved by atropine but usually not by pralidoxime. Symptoms of pyrethrin poisoning resolve without treatment.
Last full review/revision February 2013 by Gerald F. O'Malley, DO; Rika O'Malley, MD