pesticides have a long history of widespread use in the United States
and around the world. These compounds are typically very persistent
in the environment, and are known for accumulating in sediments, plants
and animals. Organochlorines have a wide range of both acute and chronic
health effects, including cancer, neurological damage, and birth defects.
Many organochlorines are also suspected endocrine disruptors.
A: Organochlorine pesticides are insecticides composed primarily of carbon, hydrogen, and chlorine. They break down slowly and can remain in the environment long after application and in organisms long after exposure.
The most notorious organochlorine is the insecticide DDT (Dichloro diphenyl trichloroethane). Promoted as a "cure all" insecticide in the 1940s, DDT was widely used in agricultural production around the world for many years. It was also the chemical of choice for mosquito control; until the 1960s, trucks sprayed DDT in neighborhoods across the U.S. DDT was also the primary weapon in the global "war against malaria" during this period, and continues to be used for malaria control in a handful of countries.
The publication of Silent Spring by Rachel Carson in 1962 raised public awareness about the dangers of pesticides, with a specific focus on persistent organochlorines and DDT. DDT was banned in many countries in the 1970s in response to public concern and mounting scientific evidence linking DDT with damage to wildlife. Since then, agricultural uses of DDT have been outlawed worldwide.
Other commonly known organochlorines that have been banned in the U.S. include aldrin, dieldrin, toxaphene, chlordane and heptachlor. Others that remain in use include lindane, endosulfan, dicofol, methoxychlor and pentachlorophenol. Detailed information on these specific pesticides is available at http://www.pesticideinfo.org/. Sample chemical structures for organochlorines are available on Pesticide Action Network's pesticide tutorial page.
A: Organochlorine pesticides are mostly used as insecticides. Specific uses take a wide range of forms, from pellet application in field crops to sprays for seed coating and grain storage. Some organochlorines are applied to surfaces to kill insects that land there. An example of this strategy is the spraying of interior home walls with DDT to control mosquitos and the malaria they carry. This is the way DDT is usually applied in those countries that are still using the pesticide for malaria control. Other organochlorines - such as chlordane, heptachlor and pentachlorophenol - are used to treat wood to prevent pest damage.
Some organochlorine pesticides are used on a wide array of crops. Endosulfan, for example, was first registered as an insecticide and miticide in the U.S. in 1954. It is still in widespread use in the U.S. to control pests in vegetables, fruits, cereal grains, and cotton, as well as ornamental shrubs, trees, vines, and ornamental plants. Internationally, its use in African cotton production is common, and it is applied to control pests on cashew plantations in India.
Lindane is another organochlorine with a range of uses. In the U.S., lindane has been used to protect crop seeds from insects, for pest control in forests, on livestock and household pets for control of ticks and other pests, and in homes to control ants and other household pests. It is also the active ingredient in many medicated shampoos and soaps to control head lice and scabies. Lindane is now restricted to seedcoating uses for a handful of grain crops, and continues to be used to control lice and scabies (except in California, where these uses were recently banned). Internationally, lindane is banned or severely restricted in 40 countries.
A: Yes. Organochlorines are some of the chemicals found most often in the hundreds of tests of human body tissue - blood, adipose tissue, breastmilk - that have been conducted around the world. Because of their chemical structure, organochlorines break down slowly, build up in fatty tissues, and remain in our bodies for a long time.
Pesticide residues on food are a major source of organochlorine exposure. In a recent analysis of organochlorine residues in the U.S. food supply, Pesticide Action Network found that even those chemicals that have been banned for decades are showing up consistently in food samples tested by the U.S. Food and Drug Administration. This can be explained in part by the long life of many organochlorines in the environment (dieldrin and the breakdown products of DDT, for example, can remain in soil for decades), and in part from the transport on wind and water currents - as well as food imports - of pesticides that continue to be used in other countries.
Inhalation and dermal contact are additional routes of exposure for individuals working directly with the pesticides (farm workers, seed treatment facility workers, etc.) as well as children who are exposed to pharmaceutical products containing the pesticide lindane. Infants also take in organochlorines in breastmilk, where the chemicals accumulate over a mother's lifetime in her fatty tissue. As discussed in detail elsewhere on this site, the benefits of breastfeeding outweigh potential health risks of this exposure, but it is a tragic cost-benefit equation to be forced to consider.
A: Organochlorines contribute to many acute and chronic illnesses. Symptoms of acute poisoning can include tremors, headache, dermal irritation, respiratory problems, dizziness, nausea, and seizures.
Organochlorines are also associated with many chronic diseases. Studies have found a correlation between organochlorine exposure and various types of cancer, neurological damage (several organochlorines are known neurotoxins), Parkinson's disease, birth defects, respiratory illness, and abnormal immune system function.
Many organochlorines are known or suspected hormone disruptors, and recent studies show that extremely low levels of exposure in the womb can cause irreversible damage to the reproductive and immune systems of the developing fetus.
A: Many organochlorines have been banned in the U.S. and other countries because of concerns about environmental impacts and human health effects.
In addition to DDT, the United States has banned aldrin, dieldrin, arochlor, chlordane, heptachlor, mirex hexachlorobenzene, oxychlordane, toxaphene and others.
However, several organochlorines are still registered for use, including lindane, endosulfan, methoxychlor, dicofol and pentachlorophenol.
Some organochlorines have been targeted for global elimination under the recently signed Stockholm Convention on Persistent Organic Pollutants (POPs). The treaty is an international effort to phase out harmful chemicals that persist in the environment and can be transported around the world. Many organochlorines fall into this category. The initial list of 12 chemicals targeted by the treaty includes nine organochlorine pesticides, all of which have already been banned in the U.S. The full list of chemicals - and a list of countries that have signed and ratified the Convention - is available at http://www.pops.int/
Due largely to resistance from the current Administration regarding the process of listing new POPs chemicals (which are still being used in the U.S.), the U.S. has not yet ratified the treaty.
A: Many organizations worldwide are pressing for ratification of the Stockholm Convention. Once the treaty goes into effect, many of the organochlorines that continue to be used in the U.S. will likely be targeted for elimination.
To urge President Bush to support the Stockholm Convention, click here!
The following organizations are working on various aspects of eliminating organochlorine pesticides and promoting alternatives. Visit their web sites and contact these organizations to learn what you can do to help.
Websites, for more information: