(Aldrin/Dieldrin, Chlordane, DDT/DDE/DDD, Endrin, Heptachlor, Kepone, Lindane, Mirex, Toxaphene)
Because toxicity and persistence are useful in killing pesticide targets, some pesticides are PBTs. The ones addressed here were chosen because they are listed as Persistent Organic Pollutants (POPs) by the United Nations. POPs are more or less defined as organic chemicals that are persistent, bioaccumulative, and toxic and have the capacity to travel long distances through the atmosphere. Only POPs that are overwhelmingly produced as pesticides are considered in this factsheet.
Most of these pesticides have been banned for use within the United States, but are still produced and used in other countries. However, many of these pesticides continue to show up in testing in the United States. This can be because of their persistence, from continuing uses for certain restricted purposes, from ongoing use of old supplies, or because of releases from old disposal sites and other environmental reservoirs, such as contaminated sediments and soils. They can also be found as residues in food from countries that use them. Agricultural "clean sweep" collections of disused pesticides in the U.S. continue to turn up significant quantities; for instance, 17 tons of DDT were collected in the U.S. in the last four years. With some local exceptions, levels of these pesticides in the U.S. environment have been declining. Despite the fact that most have been banned or severely restricted, these pesticides continue to circulate within the U.S. hazardous waste treatment system, as revealed by EPA RCRA waste records.
Pesticides are released from every step along their life cycle -- during production, repackaging, distribution, and use. Use is widespread, occurring in farms, businesses, and homes. Because these products are made to be applied to soil or water, almost all of the amount produced will eventually be released.
Aldrin and Dieldrin are pesticides used to kill soil insects such as termites or corn rootworm. They were popular for U.S. use on crops such as corn and cotton, and have been used on potatoes. They are also used to protect wooden structures from termites. EPA banned all non-termite uses of these chemicals in 1974, and all uses in 1987.
These chemicals may cause cancer and may affect immune responses in humans. They can also build up in the body and damage the nervous system. Aldrin treated rice is thought to have been a notable cause of the death of birds along the Texas Gulf Coast.
Research has indicated that dieldrin is an endocrine disruptor.
Aldrin is rapidly changed to dieldrin in animals, in plants, and in the environment. Dieldrin binds strongly to soil, with a half-life of five years in temperate areas. It is stored in fat and bioconcentrated by aquatic organisms. Diet is the main source of exposure to the public. Dieldrin was the second most common pesticide detected in a survey of U.S. pasteurized milk.
Aldrin has been found in 36 of the U.S. Superfund sites and dieldrin in 162 of them. Worldwide, about 5 tons were produced in 1994 and 87 tons imported into non-U.S. countries for use, although these numbers are highly uncertain. 2.1 million tons of RCRA hazardous waste containing aldrin or dieldrin was generated in 1995 in the U.S. It is impossible to tell how much of this waste was actually aldrin and dieldrin, and how much was other components such as soil or water.
Chlordane is a broad spectrum insecticide that has been used on a wide range of agricultural crops and for home and landscaping use. It has also been used extensively against termites. EPA banned all uses except termite control in 1983; termite control was also banned in 1988. Chlordane may still be used in the U.S. for fire ant control in power transformers.
Acute exposure to chlordane can cause neurological effects while long-term exposure can damage the liver, kidneys, and other internal organs. Significant immune system changes have also been reported by exposed workers. There is some evidence of carcinogenicity. Research has indicated that chlordane is an endocrine disruptor.
The half-life of chlordane in soil has been reported to be from one to three years. Chlordane binds to aquatic sediments and bioconcentrates in the fat of organisms. It has been detected in the indoor air of residences in the U.S., probably from use against termites. This may be an important source of exposure to the U.S. population.
Chlordane has been found in 171 Superfund sites. The chemical was very recently produced in the U.S. for export by Velsicol, a U.S. manufacturer. Velsicol shut down production in 1997 and exported its stocks. For 1994, four countries reported to the U.N. that they imported a total of 228 tons of chlordane for use. Velsicol's production was not reported in this data collection, so the numbers are probably not very accurate. 6.7 million tons of hazardous waste containing chlordane was generated in the U.S. in 1995.
DDT was widely used during the Second World War and afterwards for the control of disease vectors (such as mosquitoes) and for agricultural use, especially on cotton. It is still produced and used in many countries to control the mosquitoes that spread malaria.
Because of concern about human health effects, and about known effects on wild birds of prey, EPA banned all uses in 1972 except for use in public health emergencies. DDT may still effectively be in use in the U.S., because it is a contaminant (less than 0.1 percent) of the related and still used pesticide dicofol.
DDT breaks down into the related compounds, DDE and DDD, in the environment. DDE and DDD are also toxic and persistent.
DDT is a possible human carcinogen; DDE and DDD are probable human carcinogens. DDT and its breakdown products are thought to be endocrine disruptors.
DDT is highly toxic to birds and fish. It has a well-known eggshell thinning effect in birds of prey, which was why it severely threatened the American Eagle. In Lake Apopka, Florida, DDT and dicofol have resulted in severely abnormal reproductive development in the declining alligator population. DDT binds to fat and will both bioconcentrate and biomagnify. It is present almost everywhere in the environment, and residues have been detected in the arctic. DDT and its related compounds have a half life in soil of 10 to 15 years. DDT has been detected in human breast milk in various places, and DDE was the second most frequently found residue in tests of animal fat and eggs in Ontario, Canada.
DDT and its breakdown products have been found at 337 Superfund sites. Worldwide production in 1994 was 2,070 tons, with countries reporting export of 356 tons and import of 62 tons. 700 tons were produced in North America in 1994. One million tons of hazardous waste containing DDT or DDD were generated in the U.S. in 1995.
Endrin is an insecticide used mainly on field crops such as cotton and grains. It has also been used as a rodenticide.
Once widely used in the U.S., most uses were cancelled in 1980. It has not been produced or generally used in the U.S. since 1986.
Endrin may cause birth defects, according to some animal studies. There is limited evidence that it may depress immune responses. Long-term exposure to high levels of endrin can cause convulsions and liver damage.
Endrin is rapidly metabolised by animals and does not accumulate in fat as much as many other PBTs. However, its half life in soil may be up to 12 years. It is highly toxic to fish. It has been found in arctic freshwater.
Endrin has been found in 120 U.S. Superfund sites. Its worldwide production and use levels are uncertain. In the U.S., 5.6 million tons of hazardous waste containing endrin were generated in 1995.
Heptachlor (and Heptachlor Epoxide)
Heptachlor is an insecticide, used on insects from termites to grasshoppers to mosquitoes. Most uses were cancelled in the U.S. in 1978, with almost all remaining ones ended in 1988. It may still be used for fire ant control in buried transformers and cable boxes.
Heptachlor is metabolised in animals to heptachlor epoxide, whose toxicity is similar to that of heptachlor. Both bind to animal fat.
Heptachlor and heptachlor epoxide are possible human carcinogens. At high levels or from chronic exposure, they can cause central nervous system and liver damage. Both are thought to be endocrine disruptors.
Heptachlor has been strongly implicated in the decline of several wild bird populations. It has been detected in the blood of cattle in the U.S. The half life of heptachlor in temperate soil is up to 2 years.
Heptachlor has been found in treated wastewater from some kinds of industrial processes. These include coal mining, foundries, and nonferrous metals manufacturing. Heptachlor and its epoxide have also been found at 216 Superfund sites. Worldwide, three countries reported importing a total of 435 tons of heptachlor for use in 1994. In the U.S., 4.2 million tons of hazardous waste containing heptachlor were generated in 1995. Velsicol Chemical Corp. in Tennessee reported releasing more than a hundred pounds of heptachlor to the air in most TRI years up through 1996, indicating probable ongoing production of heptachlor.
Kepone (chlordecone) and Mirex
Kepone (the trade name for chlordecone) and mirex are two distinct but chemically similar insecticides. Kepone was used as an insecticide on tobacco, bananas and citrus trees, and in ant and roach traps. Mirex was used to control fire ants, and was also a flame retardant in plastics, paper, and electrical goods. Neither have been produced or used in the U.S. since 1978.
Kepone and mirex may reasonably be assumed to be carcinogens. Both are also thought to be endocrine disruptors. Both may cause damage to the skin, liver, nervous, and reproductive systems at high levels.
Crustaceans may be the most sensitive organisms to mirex. Both of these insecticides will bioaccumulate and biomagnify. Mirex also is very persistent, with a half life in soil of up to 10 years. It has been detected in arctic freshwater.
Mirex has been found at seven Superfund sites; kepone at two. Data on worldwide production and use are uncertain or not available. In the U.S., 980,000 tons of hazardous waste containing kepone were generated in 1995.
Hexachlorocyclohexane (HCH) exists in eight chemical forms. One of these forms, gamma-HCH, is known as lindane. Lindane has been used as an insecticide on fruit and vegetable crops, as well as forest crops. Most uses were restricted in the U.S. in 1983, but lindane is still used for treating wood, seeds, for soil treatment, as a dip for livestock, and in ointments to treat human body lice and scabies.
Lindane can cause nervous system effects and pulmonary edema from short, acute exposures. Long-term exposure can cause liver and kidney damage. It can also cause various blood disorders. Lindane may be a carcinogen, and is thought to be an endocrine disruptor.
Lindane bioconcentrates slightly in fish and crustaceans. It can remain in the air for up to 17 weeks and travel for long distances. It is broken down quickly in water.
Lindane has not been produced in the U.S. since 1977, but it is still imported to and formulated in this country. Technical-grade HCH, which contains lindane, had U.S. production halted in 1983. Lindane has been found in 239 Superfund sites. 8.4 million pounds of hazardous waste containing lindane were generated in the U.S. in 1995.
Toxaphene is an insecticide containing over 670 different chemicals. It was used mostly on cotton, but also on cereal grains, fruits, nuts, vegetables, to control ticks on livestock, and to kill fish. It was one of the most heavily used insecticides in the U.S. until 1982, when most uses of it were cancelled. It was banned in 1990.
Toxaphene is a possible human carcinogen and is thought to be an endocrine disruptor. Animal studies have shown developmental problems in newborns whose mothers were exposed during pregnancy. Exposure to high levels of toxaphene can damage the lungs, nervous system, and kidneys. It is the most elevated pollutant in Inuit living in northern Quebec.
Toxaphene has a half life in soil of up to 12 years, and is highly persistent in water with a half life of more than 200 days. As a result, it is widely distributed in water around most of the world. It is highly toxic to aquatic life.
Toxaphene has been found in 58 Superfund sites. Worldwide, one country reported producing 240 tons in 1994 and two reported importing a total of 277 tons. In the U.S., 6.7 million tons of hazardous waste containing toxaphene were generated in 1995. Toxaphene levels in Lake Superior fish have not fallen, as they have for the other four Great Lakes. This has led to some speculation about a possible local source of the chemical.
* United Nations Environment Programme. UNEP Survey on Sources of POPs: A report prepared for an IFCS Expert Meeting on Persistent Organic Pollutants. Manila, the Philippines, 17 - 19 June 1996.
* The International Programme on Chemical Safety (IPCS) within the framework of the Inter-Organization Programme for the Sound Management of Chemicals. (IOMC). An Assessment Report on: DDT-Aldrin-Dieldrin-Endrin-Chlordane-Heptachlor-Hexachlorobenzene-Mirex-Toxaphene-Polychlorinated Biphenyls-Dioxins and Furans. Prepared by L. Ritter, K.R. Solomon, J. Forget, Canadian Network of Toxicology Centres, and M. Stemeroff and C.O'Leary,
Deloitte and Touche Consulting Group. PCS/95.38. December 1995.
* Environmental Protection Agency. Great Lakes Binational Toxics Strategy Pesticide Workgroup Meeting Minutes. Great Lakes National Program Office. March 23, 1998.
* Agency for Toxic Substances Disease Registry. ToxFAQs (Aldrin/Dieldrin, April 1993, Chlordane, September 1995, DDT, DDE, and DDD, September 1995, Endrin, September 1997, Heptachlor and Heptachlor Epoxide, April 1993, Mirex and Chlordecone, September 1996, Hexachlorocyclohexane, September 1995, Toxaphene, September 1997).
* New Jersey Department of Health and Senior Services. Hazardous Substance Fact Sheets (Aldrin, November 1994, DDT, September 1996, Kepone, October 1995, Lindane, December 1995, Toxaphene, December 1994).
* Environmental Protection Agency. National Primary Drinking Water Regulations: Technical Factsheets on: (Chlordane, Endrin, Heptaclor and Heptachlor Epoxide, Lindane). Office of Ground Water and Drinking Water. January 1998.
* National Wildlife Federation. "Great Lakes Mystery: Toxaphene!" web page, http://www.nwf.org/nwf/greatlakes/toxics/toxaphen.html. Revised January 16, 1998.
* Environmental Protection Agency. Toxic Release Inventory Database (1996 "frozen" version).
* Environmental Protection Agency. Biennial Reporting System Database (1995 final version).
* Colborn, T., F.S. vom Saal and A.M. Soto. 1993. Developmental effects of endocrine-disrupting chemicals in wildlife and humans. Environmental Health Perspectives 101:378-384.