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Name: Organophosphates

Use: Pesticides

Source: synthetic chemistry, plants

Recommended daily intake: none (not essential)

Absorption: intestine, inhalation, skin

Sensitive individuals: fetus, children, elderly

Toxicity/symptoms: nervous system

Regulatory facts: RfDs exist for many insecticides. Regulated by EPA

General facts: billions of pounds used every year in agricultural and residential use

Environmental: pesticides are used globally; some are very persistent in the environment

Recommendations: avoid, consider alternatives, Integrated Pest Management


Organophosphates are a group of chemicals that have many domestic and industrial uses, though they are most commonly used as Insecticides and are responsible for a number of poisonings. The main mechanism is blocking the enzyme acetylcholinesterase causing nervous and respiratory damages that result in the insects death, but they are also hazardous to humans. After the cessation of use of organochloride insecticides, they became the most commonly used Pesticides and are responsible for 70% of pesticidal use in the United States (#PANNA).


Main article: Chemical Weapons

Organophosphates were originally developed in the 1940s as highly toxic biological warfare agents. This group of compounds are referred to as Nerve Agents and their modern derivatives are Sarin, soman, and VX.

Researchers created many compounds hoping to be able to find ones that would target characteristics of certain species, thus limiting their unwanted effects. When the organophosphate Parathion was first employed as a replacement for DDT a number of workers accustomed to handling the less toxic DDT were killed.

Chemical Structure

Though the chemical structures of organophosphates and Carbamates are very different, the mechanisms are the same. They block the aceytlcholinesterase enzyme needed remove the acetylcholine from the reaction.


Organophosphates are used in a variety of settings, though they are mostly associated with Nerve Agents or Chemical Weapons and Pesticides, though they are also used in industrial settings occasionally (#Katz, 2006).

Health Effects

Nerve agent or organophosphate poisoning results in a wide range of exposure because it affects a large number of organs and physical processes. Below is a list retrieved from the CDC site on nerve agent exposure.


  • Miosis (unilateral or bilateral)
  • Headache
  • Restlessness
  • Convulsions
  • Loss of consciousness
  • Coma
  • Rhinorrhea (perfuse watery runny nose)
  • Bronchorrhea (excessive bronchial secretions)
  • Dyspnea - (shortness of breath)
  • Chest tightness
  • Hyperpnea - (increased respiratory rate/depth) - early (increased respiratory rate/depth)
  • Bradypnea - (decreased respiratory rate) - late (decreased respiratory rate)
  • Tachycardia - (increased heart rate) - early (increased heart rate)
  • Hypertension - (high blood pressure) - early (high blood pressure)
  • Bradycardia - (decreased heart rate) - late (decreased heart rate)
  • Hypotension - (low blood pressure) - late (low blood pressure)
  • Arrhythmias Dysrhythmias (prolonged QT on EKG, ventricular tachycardia) Abdominal pain
  • Nausea and vomiting
  • Diarrhea
  • Wheezing
  • Urinary incontinence, frequency
  • Profuse sweating (local or generalized)
  • Lacrimation (tear formation)
  • Conjunctival injection
  • Weakness (may progress to paralysis)
  • Fasciculations (local or generalized)



There are a number of alternatives to organphosphates:

  • Integrated Pest Management present a series of steps to rid pests while not exposing the environment or humans to additional stress.


Prevalence of Poisonings

Pesticides are responsible for a huge number of poisonings throughout the world. Organophosphates are readily available throughout the world. The American Association of Poison Control Centers estimate that 4.2%, or over 102,000, of all poisonings in America are due to Pesticides (#eMedicine). The compounds most frequently involved with the most serious poisonings are Malathion, dichlorvos, and Trichlorfon.


Notable Organophosphates


External Links


Kamel F and Hoppin JA. Association of pesticide exposure with neurologic dysfunction and disease. Environ Health Perspect. 2004 Jun;112(9):950-8. Available online at EHPonline.

MMWR (1999). Farm worker illness following exposure to carbofuran and other pesticides - Fresno County, California, 1998. February 19, 1999, 48(6), 113-116.

Dean, S. R., & Meola, R. W. (2002). Effect of diet composition on weight gain, sperm transfer, and insemination in the cat flea (Siphonaptera: Pulicidae). J Med Entomol, 39(2), 370-375.

Dryden, M. W., & Gaafar, S. M. (1991). Blood consumption by the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae)
Dr. Kenneth Katz and Daniel Brooks. "Toxicity, Organophosphates". Aug 31, 2006. Retrieved May 24, 2007 from eMedicine.

Pesticide Action Network North America. "Phase-Out Organophosphate Pesticides: Children & Workers Matter". Retrieved on 5-24-07.

J. Routt Reigart, M.D. and James R. Roberts, M.D., MPH. Recognition and Management of Pesticide Poisonings, 5th ed.. Washington, D.C. (Environmental Protection Agency, 1999). Accessed 5-24-07.

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