Organophosphate Pesticides
Trade Secrets
Examples: Chlorpyrifos (Dursban), Methyl Parathion

Known Health Effects: Neurotoxic. Vomiting, diarrhea, abdominal cramps, dizziness, eye pain, blurred vision, confusion, numbness, twitching, paralysis, death.

Suspected Health Effects: Brain, nervous system damage. Endocrine disrupter. Liver, respiratory system toxicant. Birth defects, childhood brain tumors, leukemia and lymphomas.

The organophosphate pesticides are a family of home and agricultural bug killers, most of them in use for decades, that are at the top of the Environmental Protection Agency's priority list in the wake of a 1996 pesticide reform law aimed at protecting children. The agency recently took action against both methyl parathion – banning its use on some children's food – and Dursban (chlorpyrifos) - which was banned for all home and garden uses.

Soon after exposure to organophosphate pesticides, the human body converts the chemicals into altered forms called metabolites. Two organophosphate metabolites turned up in the test of Bill Moyers’ urine. Of the five most likely pesticides he could have been exposed to, one is for home use – pest strips and bug sprays; the other four are used as pesticides on food crops.

Originally, organophosphates were developed as nerve-gas agents for chemical warfare. They work by paralyzing muscles, and in large amounts they can kill humans and other species in the same way that they kill bugs.

According to the EPA, all organophosphates are toxic to the nervous system. They can interfere with vision, learning and memory. Chronic exposure may lead to disorientation, severe depression, irritability, confusion, headache, speech difficulties, delayed reaction times, nightmares, sleepwalking and drowsiness or insomnia, as well as numbness, cramping and weakness in the legs. In higher doses, people may suffer from vomiting, diarrhea, abdominal cramps, dizziness, eye pain, blurred vision, slurred speech, loss of reflexes, twitching, tremors of the tongue or eyelids, and eventually, paralysis of the body extremities and the respiratory muscles. The pesticides may also cause liver problems and stomach inflammation.

Young children may be especially vulnerable. According to the National Academy of Sciences, if exposure to these neurotoxic compounds occurs during the prenatal and early childhood period of brain development it “could result in permanent loss of brain function,” even at exposure levels believed to be safe for adults. Several studies have also linked early exposures with childhood brain tumors, leukemia, and lymphomas, as well as increases in birth defects.

Chlorpyrifos – sold under the trade name, Dursban - is an insecticide which was widely used in homes and on farms. On the farm, it is used to control ticks on cattle and as a spray to control crop pests. In the home, it is used to control roaches, fleas, and termites; it is also used in some pet flea and tick collars. It was the bug spray of choice for home exterminators for the past 30 years. The manufacturer estimates that chlorpyrifos has been sprayed in and around an estimated 20 million American homes every year. Now, researchers have discovered that much of this toxic pesticide winds up on children’s toys.

After pesticides are sprayed in the home, they evaporate from floors, carpets and drapes, and then re-condense on toys and pillows. In 1998, scientists at Rutgers University found that plastic and plush toys somehow attracted the pesticides more than other objects. Since young children spend a lot of time putting things in their mouths, contaminated toys are likely to give them much higher doses of poison than adults would get in the same environment.

Under the EPA’s agreement with pesticide makers, Dursban will stay on store shelves until the end of 2001, so many home supply stores are still selling Dursban products, often with the prices slashed by 50 per cent.

EPA also discovered that children frequently are exposed to heavy doses of orgahophosphates in foods such as apples, peaches, pears, plums, cherries, grapes, berries, carrots, peas, and spinach. Before EPA restricted the use of methyl parathion on those crops in 2000, the agency calculated that children were consuming eight times more of this one pesticide than EPA considered safe. Methyl parathion is still used on cotton, corn, wheat, nuts, cabbage, hops, lentils, oats, onions, rice, soybeans, beets, sunflowers, potatoes and other crops. In 1998, growers sprayed 4.2 million pounds of methyl parathion over 4.9 million acres.

pdf - EPA Human Health Risk Assessment for Methyl Parathion

pdf - EPA Hazard Assessment of Organophosphate Pesticides

Full list of sources available via e-mail
Bug spray
Organophosphates work by paralyzing muscles, and in large amounts they can kill humans and other species in the same way that they kill bugs.

PrintE-mail this to a friend
Previous Video Next Video

Photo Credit: ©2001 Corbis