What Are Organochlorine Pesticides?

Definition & Examples of OCPs

Two exterminators spraying pesticides around a home

 Huntstock / Getty Images

Organochlorine pesticides (OCPs) are a type of synthetic pesticide once used widely across the world. They are known to be highly toxic, slow to degrade, and prone to building up in the environment.

OCPs have largely been banned in the U.S. and other developed countries, but are still in use in many places in the world. Learn more about what these chemicals are and what makes them controversial.

What Are Organochlorine Pesticides?

Organochlorine pesticides are synthetic chemicals that share certain properties that make them effective as pesticides and toxic to the environment. There are many different OCPs, including DDT, Eldrin, and Lindane.

One of the chemicals known as persistent organic pollutants (POPS), organochlorines have extremely strong bonds between their chlorine and carbon components and are attracted to fats. They are also highly insoluble in water, meaning they don’t dissolve, and when it rains, they can spread widely through runoff. The problem with this strength is that once organochlorine pesticides are used, they stay around for a long time, not only in the water supply and in the soil but also in human and animal bodies.

  • Acronym: OCP

Most pesticides are bad news, but organochlorine pesticides are super-long-lasting pesticides, which makes them very bad news. Most industrialized nations have banned many or all OCPs from production and use, but many are still in use in developing countries.

How Organochlorine Pesticides Are Used

The biggest application for organochlorine pesticides is as an insecticide, and they were widely used from the 1940s to the 1960s in the United States and Europe. Probably the most infamous organochlorine insecticide is DDT. It was so effective as a mosquito killer, enabling an estimated one billion people to live free from fear of malaria, that the chemist who discovered its insecticide powers received a Nobel Prize.

DDT was used widely in the United States until biologist Rachel Carson published her groundbreaking book "Silent Spring," which warned of the toxicity of the chemicals. Scientists confirmed DDT had disastrous effects on the reproductive abilities of birds, fish, and marine animals, and it was banned in the United States in 1972.

By the time it was banned, however, over 1.3 billion pounds of the chemical had already been applied throughout the country. Thirty years later, testing still found evidence of the chemical in air, water, and rain, soil and dust, plants, animals, and humans, including people born long after the DDT ban went into effect.

In 2006, the United Nations reversed course and began promoting DDT's use in countries that allow it to control mosquitoes and combat malaria, which kills more than one million people each year. 

The Dangers of Organochlorine Pesticides

When used, organochlorine pesticides can leach into the environment via direct application, contaminated waste disposal, incinerator emissions, or runoff. If you are near an area where an organochlorine pesticide has recently been applied, you can actually inhale the chemicals. You can also ingest them by eating contaminated foods, such as fish, dairy products, and other foods with higher fat content.

Since organochlorine pesticides don't break down easily in fatty tissue, they can build up in animals and humans and even be passed on in this manner. For example, studies show that when a human or bird or other fish eats a fish that is contaminated with an organochlorine pesticide, that pesticide is passed on to the eater.

Long-term exposure in humans can have serious health effects, including damage to the liver, kidneys, thyroid gland, bladder, and central nervous system as well as potentially serious reproductive problems.

Symptoms of OCP Exposure

Long-term exposure to OCPs can cause a variety of symptoms in humans, including:

  • Headaches, confusion, and dizziness
  • Digestive problems such as abdominal pain, nausea, vomiting and diarrhea
  • Agitation or a sense of apprehension
  • Weakness, loss of muscle control and tremors, even seizures

People also may suffer skin, ear, nose, or throat irritation and breathing problems or a cough. If anyone suspects they suffer from exposure, they should see a doctor.

Alternatives to Organochlorines

Finding effective alternatives to pesticides—organochlorines, in particular—is a major global challenge. Much of modern agriculture depends on pesticide use for reliable crop production, and officials struggle to contain public threats such as malaria without the use of organochlorines such as DDT.

That's not to say alternatives don't exist, but many of them do require more extensive education in order for farmers or developing communities to implement them. In agriculture, these methods include promoting crop tolerance, companion planting, considering disease potential in crops, and a variety of pest control techniques. In public health, methods may include introducing insect predators, clearing vegetation cover, and draining standing water.

Key Takeaways

  • Organochlorine pesticides (OCPs) are a type of synthetic pesticide known to be highly toxic, slow to degrade, and prone to building up in the environment.
  • Many OCPs, such as DDT, have been banned in industrialized countries, but some are still approved for use in developing nations where diseases such as malaria are a major problem.
  • Long-term negative health effects of organochlorine exposure in humans include damage to the liver, kidneys, thyroid gland, bladder, and central nervous system as well as potentially serious reproductive problems.
  • There are effective alternatives to using organochlorines and other pesticides, but these methods require extensive education.