POPs are highly toxic and persistent chemicals that travel globally.
What are persistent organic pollutants (POPs)?
Persistent organic pollutants (POPs) are a group of organic, or carbon-based, chemicals that are highly toxic and persistent in the environment. They can also travel great distances and become widely distributed through natural processes, and accumulate in the fatty tissue of living things. POPs are either used as pesticides, used by industry, or generated unintentionally as by-products of industrial or combustion processes.
POPs increasingly accumulate as they move up the food chain, reaching the greatest concentrations in predatory birds, fish, mammals, and humans. POPs circulate regionally and around the world in the atmosphere and oceans, by wind and water, and travel easily from one location to other distant parts of the world.
In 2001, more than 100 countries signed the Stockholm Convention on Persistent Organic Pollutants, which commits them to reduce or eliminate the production, use, and release of the 12 POPs of greatest concern. These 12 chemicals, commonly called the “dirty dozen,” are aldrin, chlordane, DDT, dieldrin, dioxins, endrin, furans, heptachlor, hexachlorobenzene, mirex, PCBs, and toxaphene.
Aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, and toxaphene are insecticides or pesticides. Aldrin, chlordane, dieldrin, and heptachlor are used to control termites. Endrin is used to control rodents. Hexachlorobenzene and PCBs are industrial chemicals. Dioxins, furans, hexachlorobenzene, and PCBs also are by-products from most forms of burning, including industrial burning, burning wood or trash, cigarette smoke, and automobile exhaust.
In 2009, the Stockholm Convention listed an additional nine chemicals as POPs to eliminate or restrict. Five are pesticides: chlordecone; alpha hexachlorocyclohexane; beta hexachlorocyclohexane; lindane; and pentachlorobenzene. Four are industrial chemicals: hexabromobiphenyl; tetrabromodiphenyl ether and pentabromodiphenyl ether; hexabromodiphenyl ether and heptabromodiphenyl ether; and perfluorooctane sulfonic acid, its salts, and perfluorooctane sulfonyl fluoride.
From the early 1930s to late 1980s, the Navajo Nation and Bureau of Indian Affairs used toxaphene and lindane-based solutions to treat sheep in dip vats on sheep ranches. Both of these chemicals are POPs.
Several additional substances now considered to be POPs are generated as by-products of combustion processes, such as polycyclic aromatic hydrocarbons (PAHs). Other POPs are used in consumer products, such as polybrominated diphenyl ethers (PBDEs).How might I be exposed to POPs?
POPs have been found on every continent in the world and in every major climate zone, including remote regions such as oceans and deserts. They are also found in the body fat of human beings and every wildlife species.
Although many of the POPs in the Stockholm Convention are no longer produced in the United States, people can still be at risk from POPs that have persisted in the environment or been unintentionally released in the United States or other countries.
You can be exposed to POPs through outdoor air or indoor air and in drinking water. At home, you can be exposed to POPs if you eat fatty foods with high concentrations of POPs. You can be exposed if you use pesticides in your yard or garden. POPs can be passed from a pregnant woman to a developing fetus and to infants from a nursing mother’s breast milk.
You may be at particular risk of exposure to POPs if you consume large amounts of fish, shellfish, or wild foods that are high in fat. Indigenous people may be at risk if they are subsistence hunters and fishers.
At work, you can be exposed to POPs if you work in industrial processes that are the most likely sources of POPs: manufacturing, thermal practices involving high temperatures and combustion, product application and use, recycling, and waste disposal.
Manufacturing processes that may expose you to POPs include production of chlorine and chlorinated organic chemicals, oil refining, and pulp and paper production. Processes that use heat may expose you to POPs and include operating blast furnaces or cement kilns; scrap metal processing; mineral processing; incineration of municipal waste, industrial waste, hazardous waste, sludge, or medical/clinical waste; operating vehicle combustion engines, especially diesel engines; copper smelting; wood, landfill gas, oil, coal, or biomass combustion; accidental fires; and landfill, plastic container, or electrical waste burning.
Product applications and uses that may expose you to POPs include pesticide and herbicide application; textile, wood, and leather dyeing and finishing; industrial bleaching; use of paints containing PCBs; transformer and electrical equipment use; and solvent use and applications.
Recycling processes that may expose you to POPs include metal, paper, plastics, and metal fly ash recycling; application of sewage and paper sludge on land for fertilizer; and solvent and waste oil recovery. Waste disposal processes that may expose you include operating landfills that contain sludge, fly ash, or metal ash; ocean dumping; storage or stockpiling of transformers; and disposal of treated wood, such as telephone poles or railroad ties.How can POPs affect my health?
Of the original 12 POPs covered by the Stockholm Convention, TCDD dioxin is listed as a human carcinogen in the Twelfth Report on Carcinogens published by the National Toxicology Program, and six are listed as "reasonably anticipated to be human carcinogens" : DDT, furan, hexachlorobenzene, mirex, PCBs, and toxaphene. Lindane and hexachlorocyclohexane are also listed as anticipated to be human carcinogens.
Exposure to POPs can cause birth defects, cancer, and damage to the nervous, human hormonal, reproductive, and immune systems. If exposure to POPs is high enough, it can also cause death.
Some POPs, particularly DDT, dioxins, and PCBs, are considered to be endocrine disruptors, which are chemicals that may interfere with the production or activity of hormones in the human endocrine system.
Exposure to POPs can also cause learning, developmental, and behavioral disorders; allergies; hypersensitivity; poor coordination; and problems for nursing mothers.
Women, infants, children, and the elderly appear to be especially vulnerable to certain effects of POPs.
If you think your health has been affected by exposure to POPs, contact your health care professional.
For poison emergencies or questions about possible poisons, contact your local poison control center at 1-800-222-1222.
This description is based on the information found in the Web links listed with this topic.
Persistent Organic Pollutants (United Nations Environment Programme)
Persistent Organic Pollutants in the Arctic (National Oceanic and Atmospheric Administration)
Persistent Organic Pollutants: A Global Issue, A Global Response (Environmental Protection Agency)
What Are POPs? (World Bank Group)
Last Updated: April 22, 2014