Organophosphates are chemicals that feature in agricultural products, such as herbicides, pesticides, and insecticides. Exposure to organophosphates can be harmful.

Other uses of organophosphates include nerve gas, such as Sarin, and the production of plastics and solvents.

Poisoning can occur after short or long-term exposure. It can cause nerve damage and disrupt hormone production in humans and animals. Organophosphates are also toxic to plants and insects.

Agricultural workers and others who handle agricultural chemicals may be at risk, with most exposure occurring in rural areas. However, organophosphates can also be present in food products such as wheat, flour, and cooking oil. The use of ant and roach spray may also lead to exposure.

In the United States, around 8,000 people per year come into contact with organophosphates but fatalities are rare. Worldwide, however, it affects around 3 million people annually and is responsible for some 300,000 deaths. The U.S. government introduced tighter rules regarding the use of organophosphates in 2013.

This article looks at organophosphate poisoning, how to recognize it, the risk factors, and what to do if poisoning occurs.

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Organophosphate poisoning symptoms can range from mild to severe and vary widely depending on the type and degree of exposure. In more severe cases, it can be life-threatening. Symptoms will depend on the length of exposure and the strength of the chemical involved.

Experts classify the effects of toxicity by the length of exposure:

  • acute effects occur within minutes to 24 hours
  • subacute effects appear 24 hours to 2 weeks after exposure
  • chronic effects appear from weeks to several years after exposure

Symptoms are similar whether exposure is short or long-term, but long-term exposure may lead to significant long-term complications. Symptoms can also be mild, moderate, or severe, depending on the intensity of exposure.

Both acute and chronic exposure can lead to:

  • increased production of saliva and tears
  • increased urination
  • diarrhea, nausea, and vomiting
  • small pupils
  • sweating
  • muscle tremor
  • memory loss
  • confusion and anxiety
  • drowsiness
  • breathing difficulty
  • headaches
  • emotional changes
  • hallucinations
  • changes in heart rhythm and other cardiovascular symptoms
  • seizures

Symptoms can appear within minutes and take several weeks to disappear.

Organophosphate exposure can also lead to long-term complications. Again, the severity will depend on the extent and length of exposure.

Complications can affect the following body systems:

Respiratory symptoms

  • aspiration pneumonia due to excess saliva production
  • respiratory failure, as the respiratory muscles become weaker
  • severe bronchospasm
  • accumulation of fluid around the lungs

Cardiovascular system

  • irregular heart rhythm
  • fast or slow heart rhythm
  • high or low blood pressure

Nervous system

  • changes in mental state
  • psychosis
  • seizures
  • hallucinations
  • neuropathy
  • lethargy
  • irritability
  • memory problems
  • Parkinsonism

Digestive and metabolic symptoms

  • electrolyte imbalance and low bicarbonate levels
  • pancreatitis
  • high blood sugar

It can also increase the risk of kidney problems, and some reports say it may increase the risk of cancer.

Organophosphates can enter the body through:

  • the respiratory system
  • direct contact with the skin
  • the mouth and digestive system

Inside the body, they stop the production of an enzyme known as acetylcholinesterase (AChE). This enzyme helps break down the neurotransmitter acetylcholine, present in the peripheral and central nervous systems. This leads to a buildup of acetylcholine and overstimulation of the nicotinic and muscarinic receptors.

These receptors play a role in various body functions, including hormone and saliva production, and the functioning of smooth muscle, such as that found in the cardiovascular and digestive systems.

Organophosphate poisoning can occur if a person is exposed to the chemicals in high doses or over a long time.

The risk of organophosphate poisoning is higher in:

  • agricultural and rural settings
  • homes and gardens
  • veterinary practices
  • employment in agriculture, pest control, and some industries

Organophosphates may also be present in food, due to the spraying of crops, for example. However, research suggests that foods in the U.S. are unlikely to contain enough organophosphate to cause toxicity.

A 2021 study raises concerns about the impact of organophosphate exposure on children in countries with lower incomes, specifically Egypt. The authors note that organophosphates are one of the most common causes of poisoning globally due to their low cost and easy availability.

The study looked at data for 108 children aged 16 and under who received treatment for organophosphate poisoning in one hospital in 2019. Of these, 87% of cases were accidental and 13% were attempted suicides.

In some places, such as Nepal, there are concerns about the use of organophosphates in suicide. Factors contributing to this include a lack of mental health support services and the fact that organophosphates are readily available.

If a person experiences symptoms following exposure to organophosphates, a doctor will likely:

  • consider the symptoms
  • ask about the exposure
  • order blood tests

If a person shows strong signs of acute poisoning, experts advise starting treatment at once and without waiting for laboratory results, as these can take time.

If a person comes into direct contact with organophosphates, they should:

  • remove their clothing
  • immediately wash with water and liquid soap
  • remove any contact lenses and irrigate the eyes with lukewarm water

Anyone who is helping the person should ensure they, too, have protection.

Treatment will aim to:

  • ensure the person is breathing effectively
  • stop the body from absorbing any more of the toxin
  • restore the function of the muscarinic and nicotinic receptors

Atropine will work on muscarinic receptors. A doctor will start with a dose of 2–5 milligrams (mg) intravenously and add to the dose every 3–5 minutes until saliva clears from the lungs and the airways are no longer restricted.

After this, the doctor will give at least 30 mg of pralidoxime intravenously over 30 minutes to restore the function of the nicotinic receptors. The person will need to have this within 48 hours of exposure. The doctor may add to the dose until symptoms improve.

Anyone who experiences symptoms of organophosphate poisoning should spend time in the hospital under observation. They often can leave the hospital after 12 hours without symptoms.

People who work with organophosphates should:

  • wear full protective gear during and after applying them
  • take a bath or shower at the end of the working day and wash before eating or drinking
  • know which products contain organophosphates and how to recognize them
  • keep products in a secure place and mark them clearly

Other people may wish to:

  • avoid using products containing organophosphates
  • stay indoors with the windows closed if spraying occurs nearby
  • test well water regularly, if applicable
  • wash all fruits and vegetables before use

Organophosphates are generally formulated as colorless to brown liquids. They may have no odor or a fruity smell.

Globally, the mortality rate after exposure to organophosphate varies from 2–25%, but this will depend on various factors, including the degree and type of exposure and the level of healthcare available. The most common cause of death is respiratory failure.

A 2020 article published by the BMJ describes the outcome as “favorable” for people exposed accidentally or at work.

Organophosphates are used in agricultural products such as insecticides and the manufacture of solvents and plastics. Exposure can be toxic. The severity of the impact will depend on the product and the length and intensity of exposure.

Anyone who experiences symptoms after exposure to organophosphates needs immediate medical attention. People who work with organophosphates over the long term and begin to notice symptoms should also seek medical advice.

In cases of attempted suicide with organophosphate, a person should call 911 immediately. It is important for people thinking about suicide to know there are other options. If a person is thinking about suicide, they are urged to call the National Suicide Prevention Lifeline at 1-800-273-8255.