Farm Chemical Safety Series

Recognizing Pesticide Poisoning

Organophosphate Insecticides

Organophosphate insecticides affect people in much the same way they affect insects -- the nervous system is damaged and breathing becomes difficult. Symptoms of acute organophosphate poisoning usually appear within 4 hours of the exposure. Common, early symptoms may include headache, nausea, and dizziness. The victim may also appear anxious and restless.

Later symptoms of a worsening condition are muscle twitching, weakness, abdominal cramps, and vomiting. Sweating, salivation, and tearing are often seen. Dark or blurred vision and constricted pupils are other symptoms that may occur. Tightness of the chest and coughing may lead to respiratory depression, or the lungs may fill with fluid. Either way, without immediate medical attention, the victim may die. Two antidotes doctors use for treating organophosphate poisonings are atropine and 2-PAM. Large doses of the antidote may be needed for a severe poisoning, and follow-up doses may need to be given for several hours to several days.

After-effects of a severe poisoning can last 1 to 3 weeks after the initial exposure. Some effects may last 1 to 3 months. The full long-term health effects of continued exposure to low doses over time are not well understood. It is suspected they might cause anorexia and weakness.

Carbamate Insecticides

Early symptoms of carbamate poisoning include weakness, dizziness, and sweating. Headache, salivation, vomiting, and diarrhea are also common. Later symptoms include constricted pupils, lack of coordination, and slurred speech. As with organophosphates, tightness in the chest and coughing may precede lung failure or fluid entering the lungs.

The symptoms of a carbamate insecticide poisoning appear more quickly, are more easily reversed, and persist for a shorter time than do the symptoms of an organophosphate poisoning. Its fast action makes it imperative for a person to seek immediate medical treatment at the first sign of a poisoning. While the amount of carbamate or organophosphate required to produce symptoms may be the same, a greater amount of carbamate active ingredient is usually required to threaten the victim's life. Importantly, blood tests do not easily identify carbamate in the body, so taking the label or MSDS to the hospital can be especially critical. The antidote for carbamate poisoning is atropine, which may have to be given in large doses.

Organochlorine Insecticides

Early signs of an organochlorine poisoning may involve the senses. The skin of the face and extremities may burn, itch, or have greater than normal sensitivity. Headache, dizziness, vomiting, lack of coordination, and confusion are common symptoms. Later, more severe symptoms include seizures and convulsions, followed by coma and lung failure. Certain organochlorines, such as heptachlor, may cause the sudden onset of convulsions with no earlier symptoms. Convulsions may recur for several days.

Unlike many other pesticides, there is no direct antidote for organochlorine poisonings. Drugs can be given to help control the convulsions, and artificial respiration may keep the lungs functioning. Ultimately, the body must be given enough time to rid itself of the chemical.

Arsenic-Containing Pesticides

Arsenic-containing pesticides are also among the more toxic pesticides. Arsenic compounds affect the nervous system, liver, kidneys, and other vital body tissues. Poisonings from absorption through the skin are rare. Most victims of arsenic pesticide poisonings have swallowed the chemical.

Symptoms usually appear within one hour after ingestion but may be delayed several hours. One distinctive sign of an arsenic compound poisoning is a garlic odor of the breath of the victim. Other symptoms include inflammation of the mouth and throat. Burning abdominal pain, thirst, vomiting, and diarrhea are common symptoms. Later symptoms include headache, dizziness, muscle weakness, hypothermia, convulsions, and coma. Lethal poisonings usually cause death 1 to 3 days after the exposure.

Chlorophenoxy Herbicides

Chlorophenoxy herbicides are commonly used around Mississippi. They are moderately irritating to the skin, eyes, and sinuses. Long-term contact with the skin may result in loss of pigmentation in the skin. These compounds remain in the body for relatively short periods of time, days instead of weeks or months.

Most information on chlorophenoxy poisonings was gained through attempted suicides by ingestion of large doses. Few of these victims died. Some effects, such as muscle weakness, may linger for months. Inhaling sprays may cause burning in the throat and chest, coughing, and dizziness. Ingesting the pesticide usually causes vomiting and can cause pain in the chest and abdomen. Symptoms of a severe poisoning include headache, confusion, bizarre behavior, and unconsciousness. Victims are still able to breathe, but hyperventilation sometimes occurs.

There is no direct antidote for chlorophenoxy poisonings. If the pesticide were swallowed, medical professionals may give charcoal to the victim and attempt to empty the contents of the stomach. Fluids may be given intravenously to help remove the chemical and flush out the kidneys. If the body is able to remove the chemical from its system, consciousness should return in 48 to 96 hours.

Pyrethroids

Pyrethroid insecticides are also commonly used and, fortunately, are some of the least toxic to mammals. Poisonings by pyrethroids are rare, probably because of the low absorption rate through the skin and rapid breakdown. Also, the kidneys are capable of promptly excreting most pyrethroids.

High doses may cause tremors, loss of coordination, salivation, vomiting, and irritability. Extreme doses may cause convulsions. Milder doses may cause skin irritations, such as burning, itching, or stinging. These sensations may progress to a numbness in the affected areas. The face is the most commonly affected area, while the hands, arms, and neck are sometimes affected. These effects are usually felt within 1 to 2 hours of the exposure but may appear within minutes. Sweating, sun, and heat will make the sensations worse. Most sensations are gone within 24 hours.

Review Questions

1. How soon after the appearance of symptoms should the victim be gotten to the hospital?
2. What should be taken to the hospital with the victim?
3. Is there an antidote available for all pesticides, just in case someone is poisoned?

Answers

1. Immediately
2. The pesticide label and Material Safety Data Sheets.
3. No

Some common active ingredient names, with a brand name product that contains that active ingredient, are given below. Note: Also provided is the Rat Oral LD 50 in mg/kg for each active ingredient. This LD 50 is the dosage of active ingredient, not on-shelf chemical, given orally that will kill 50 percent of a group of rats all given that dosage. For example: if rats in a group were each fed 980 milligrams of acephate per kilogram of the rat's body weight, 50 percent of the rats could be expected to die. Also, a man weighing 200 pounds would be threatened by swallowing only two-tenths of an ounce of Furadan 4F. By contrast, the same 200-pound man would have to swallow 3 1/2 ounces of Ammo 2.5 EC to threaten his life.

By Trent Spencer, Extension Agricultural Engineering Program Assistant, and Herb Willcutt, Extension Agricultural Engineer

Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status.

Publication 1933
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director