The Stockholm Convention on Persistent Organic Pollutants was adopted by the Conference of Plenipotentiaries on 22 May 2001 in Stockholm, Sweden. The Convention entered into force on 17 May 2004.
The Stockholm Convention on Persistent Organic Pollutants is a global treaty to protect human health and the environment from chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or on the environment.
Exposure to Persistent Organic Pollutants (POPs) can lead to serious health effects including certain cancers, birth defects, dysfunctional immune and reproductive systems, greater susceptibility to disease and damages to the central and peripheral nervous systems.
Given their long range transport, no one government acting alone can protect its citizens or its environment from POPs.
In response to this global problem, the Stockholm Convention, which was adopted in 2001 and entered into force in 2004, requires its parties to take measures to eliminate or reduce the release of POPs into the environment.
As set out in Article 1, the objective of the Stockholm Convention is to protect human health and the environment from persistent organic pollutants.
Among others, the provisions of the Convention require each party to:
- Prohibit and/or eliminate the production and use, as well as the import and export, of the intentionally produced POPs that are listed in Annex A to the Convention (Article 3)
Annex A allows for the registration of specific exemptions for the production or use of listed POPs, in accordance with that Annex and Article 4, bearing in mind that special rules apply to PCBs. The import and export of chemicals listed in Annex A can take place under specific restrictive conditions, as set out in paragraph 2 of Article 3.
- Restrict the production and use, as well as the import and export, of the intentionally produced POPs that are listed in Annex B to the Convention (Article 3)
- Annex B allows for the registration of acceptable purposes for the production and use of the listed POPs, in accordance with that Annex, and for the registration of specific exemptions for the production and use of the listed POPs, in accordance with that Annex and Article 4. The import and export of chemicals listed in Annex B can take place under specific restrictive conditions, as set out in paragraph 2 of Article 3.
- Reduce or eliminate releases from unintentionally produced POPs that are listed in Annex C to the Convention (Article 5)
The Convention promotes the use of best available techniques and best environmental practices for preventing releases of POPs into the environment.
- Ensure that stockpiles and wastes consisting of, containing or contaminated with POPs are managed safely and in an environmentally sound manner (Article 6)The Convention requires that such stockpiles and wastes be identified and managed to reduce or eliminate POPs releases from these sources. The Convention also requires that wastes containing POPs are transported across international boundaries taking into account relevant international rules, standards and guidelines.
- To target additional POPs (Article 8)The Convention provides for detailed procedures for the listing of new POPs in Annexes A, B and/or C. A Committee composed of experts in chemical assessment or management – the Persistent Organic Pollutants review Committee, is established to examine proposals for the listing of chemicals, in accordance with the process set out in Article 8 and the information requirements specified in Annexes D, E and F of the Convention.
- Other provisions of the Convention relate to the development of implementation plans (Article 7), information exchange (Article 9), public information, awareness and education (Article 10), research, development and monitoring (Article 11), technical assistance (Article 12), financial resources and mechanisms (Article 13), reporting (Article 15), effectiveness evaluation (Article 16) and non-compliance (Article 17).
What is the Purpose of the Convention?
The purpose of the Stockholm Convention is to restrict and eventually prohibit the production, use, emissions and import and export of highly toxic substances known as persistent organic pollutants (POPs).
What Substances or Chemicals Are Covered by the Convention?
The Convention currently covers 12 compounds, ‘poisons without passports’ that are:
- organic (carbon based);
- persistent, resisting degradation in the environment;
- bioaccumulative in fatty tissue;
- capable of transboundary movement, travbelling vast distances on air
- and water currents; and
- are toxic to humans and wildlife.
They include the:
- organochlorine pesticides; DDT, endrin, dieldrin, aldrin, chlordane,
- toxaphene, heptachlor, mirex, hexachlorobenzen (HCB); and
- industrial chemicals and by-products; polychlorinated biphenyls (PCBs), HCB dioxins and furans. ,
There are a further twelve chemicals that are being assessed by the POP Review Committee after being nominated by a Party.
- Pentabromodiphenyl ether (Penta BDE)
- Perfluorooctane sulfonate (PFOS)
- Alpha & Beta hexachlorocyclohexane (Lindane isomers)
- Octabromodiphenyl ether (OctaBDE)
- Short-chained chlorinated paraffins (SCCPs)
What are the likely Scenarios where a Developing Country or a Country in Economic Transition would use this Convention?
Most developing countries and countries with economies in transition have some quantity of POPs sitting in stockpiles or scattered around the country. Becoming a Party to the Stockholm Convention provides an opportunity for developing countries and countries with economies in transition to get assistance to address POPs legacies by ensuring safe removal and disposal of future POPs, as well as such as eliminating dioxins and furans emissions. Some of these activities are already underway and includes removal and treatment of old pesticides and PCB contaminated electrical insulators in Pacific Islands which are being dealt with by the SPREP POP in PIC Project. Meanwhile in Africa the African Stockpiles Programme (see the Bamako Convention section) is preparing to carry out similar projects in African countries who have signed up to the Stockholm and/or Basel Conventions.
What are the Economic and Social Benefits of the Convention?
POPs are highly toxic substances found throughout the world. Banning the use and trade in these chemicals will provide considerable human health benefits, as it will stop them entering the food chain. Available funding for POPs implementation has the secondary benefits of building capacity for general chemical management including implementation of the other relevant treaties.
What are the Costs Associated with the Convention?
There is an administrative fee and there are costs associated with developing a National Implementation Plan but funding is available to assist developing countries and countries with economies in transition. Depending on the amount of POPs being produced or stockpiled in your country there will be some operational costs. The competent authorities (eg environment department, police, customs officers, port or airport authorities) may need to carry out the following functions:
- identification of POPs;
- knowledge of companies’ operations that may produce POPs;
- understanding of laboratory results on sampling and testing; and
- understanding of methods to minimise or destroy POPs in an environmentally sound manner;
Will National Legislation be Required?
Yes. However, because of similarities with other chemical conventions, a single hazardous chemicals Act could be developed.
Are There Reporting Requirements?
Yes. Each party is required to provide to the Secretariat information on:
- measures taken to implement the Convention;
- effectiveness of measures;
- statistical data on its total quantities of production, import and export of POPs;
- a list of states from which it has imported and states to which it has exported POPs.
Will There be Help in Administering the Convention?
It is likely that the Secretariat will provide assistance to developing countries. SPREP may provide assistance as part of their involvement with the Waigani Convention and the African Union may provide similar assistance in African Countries.
What is the Status of the Convention?
The Convention entered into force on the 17 May 2004 when France became the 50th nation to ratify the Convention.
Are There Other Agreements Associated with the Convention?
There are strong linkages with the Basel, Bamako and Waigani Conventions as the types of chemicals overlap. Preliminary Low POPs waste guidelines (15 ppb for dioxins and 50 ppm for all other POPs) were developed by the Open ended Working Group of the Basel Convention as required by Article 6 of the Stockholm Convention. The decision includes methods listed under Basel Convention Technical Guidelines for POPs wastes as environmentally sound methods to destroy POPs waste. The standards for the destruction or permanent transformation of POPs are to be carried out in collaboration with appropriate bodies of the Basel Convention.
The Stockholm Convention on Persistent Organic Pollutants was adopted on 22 May 2001 and entered into force on 17 May 2004.
Being aware that persistent organic pollutants (POPs) pose major and increasing threats to human health and the environment, in May 1995 the Governing Council of UNEP requested in its decision 18/32 that an international assessment process be undertaken of an initial list of 12 POPs and that the Intergovernmental Forum on Chemical Safety (IFCS) develop recommendations on international action for consideration by UNEP Governing Council and World Health Assembly no later than 1997.
In June 1996, IFCS concluded that available information was sufficient to demonstrate that international action, including a global legally binding instrument, was required to minimize the risks from the 12 POPs through measures to reduce and/or eliminate their emissions or discharges.
In February 1997, the UNEP Governing Council in its decision 19/13C invited UNEP to prepare for and convene intergovernmental negotiating committee (INC), with a mandate to prepare an international legally binding instrument for implementing international action initially beginning with the 12 POPs and requested that the INC establish an expert group to develop criteria and a procedure for identifying additional POPs as candidates for future international action.
The first meeting of the INC to develop an internationally legally binding instrument for implementing international action on POPs was held in June 1998 in Montreal, Canada, at which the Criteria Expert Group (CEG) requested above was established. Subsequent meetings of the INC were held in Nairobi, Kenya, in January 1999, in Geneva, Switzerland, in September 1999, in Bonn, Germany, in March 2000, and in Johannesburg, South Africa, in December 2000 where the negotiations were successfully completed.
The CEG completed its mandate in two meetings: the first in Bangkok, Thailand, in October 1998 and, the second, in Vienna, Austria, in June 1999.
The Convention was adopted and opened for signature at a Conference of Plenipotentiaries held from 22 to 23 May 2001 in Stockholm, Sweden.
The Conference of the Plenipotentiaries also adopted a number of resolutions that were included in the appendix to the Final Act, such as on interim arrangements; on the Secretariat (e.g. inviting UNEP to convene further sessions of the INC during the interim period); and on liability and redress. On this latter issue, a workshop on liability and redress was held on 19-21 September 2002 in Vienna, Austria.
The Convention entered into force on 17 May 2004, ninety days after submission of the fiftieth instrument of ratification, acceptance, approval or accession in respect of the Convention.
The Stockholm Convention on Persistent Organic Pollutants was adopted at a Conference of Plenipotentiaries on 22 May 2001 in Stockholm, Sweden. The Convention entered into force on 17 May 2004, ninetieth day after the date of deposit of the fiftieth instrument of ratification, acceptance, approval or accession in respect of the Convention.
Article 18 of the Convention requires the Conference of the Parties to adopt arbitration and conciliation procedures to govern the settlement of disputes between Parties to the Convention. At its first meeting held in Punta del Este, Uruguay from 2 to 6 May 2005, the Conference of the Parties adopted decision SC-1/2, by which it established such procedures. The procedures are set out in Annex G, which entered into force on 27 March 2007 (Reference: C.N.1017.2007.TREATIES-14).
At its fourth meeting held in Geneva from 4 to 8 May 2009, the Conference of the Parties adopted amendments to Annexes A, B and C by decisions SC-4/10, 4/11, 4/12, 4,/13, 4/14, 4/15, 4/16, 4/17 and 4/18 to list additional nine chemicals in the respective annexes: alpha hexachlorocyclohexane; beta hexachlorocyclohexane; chlordecone; hexabromobiphenyl; hexabromodiphenyl ether and heptabromodiphenyl ether; lindane; pentachlorobenzene; perfluorooctane sulfonic acid, its salts and perfluorooctane sulfonyl fluoride; and tetrabromodiphenyl ether and pentabromodiphenyl ether. The amendment was communicated by the depositary to all Parties on 26 August 2009 (Reference: C.N.524.2009.TREATIES-4).
At its fifth meeting held in Geneva from 25 to 29 April 2011, the Conference of the Parties adopted an amendment to Annex A by decision SC-5/3 to list technical endosulfan and its related isomers in the annex. The amendment was communicated by the depositary to all Parties on 27 October 2011 (Reference: C.N.703.201.TREATIES-8).
At its sixth meeting held in Geneva from 28 April to 10 May 2013, the Conference of the Parties adopted an amendment to Annex A by decision SC-6/13 to list hexabromocyclododecane in the annex. The amendment was communicated by the depositary to all Parties on 26 November 2013 (Reference C.N.934.2013.TREATIES-XXVII.15).
In accordance with paragraphs 3 (b) and 3 (c) and paragraph 4 of Article 22 of the Convention, any Party that is unable to accept an amendment to Annex A, B or C shall so notify the depositary, in writing, within one year from the date of communication by the depositary of the adoption of the amendment. The depositary shall without delay notify all Parties of any such notification received. A Party may at any time withdraw a previous notification of non-acceptance in respect of any amendment to Annex A, B or C, and the amendment shall thereupon enter into force for that Party subject to paragraph 3 (c) of Article 22. On the expiry of one year from the date of the communication by the depositary of the adoption of the amendment to Annex A, B or C, the amendment shall enter into force for all Parties that have not submitted a notification in accordance with the provisions of paragraph 3 (b) of Article 22.
In accordance with paragraph 4 of Article 22, an amendment to Annex A, B or C shall not enter into force with respect to any Party that has made a declaration with respect to any amendment to those Annexes in accordance with paragraph 4 of Article 25, in which case any such amendment shall enter into force for such a Party on the ninetieth day after the date of deposit with the depositary of its instrument of ratification, acceptance, approval or accession with respect to such amendment.
Persistent Organic Pollutants (POPs) are organic chemical substances, that is, they are carbon-based. They possess a particular combination of physical and chemical properties such that, once released into the environment, they:
- remain intact for exceptionally long periods of time (many years);
- become widely distributed throughout the environment as a result of natural processes involving soil, water and, most notably, air;
- accumulate in the fatty tissue of living organisms including humans, and are found at higher concentrations at higher levels in the food chain; and
- are toxic to both humans and wildlife.
As a result of releases to the environment over the past several decades due especially to human activities, POPs are now widely distributed over large regions (including those where POPs have never been used) and, in some cases, they are found around the globe. This extensive contamination of environmental media and living organisms includes many foodstuffs and has resulted in the sustained exposure of many species, including humans, for periods of time that span generations, resulting in both acute and chronic toxic effects.
In addition, POPs concentrate in living organisms through another process called bioaccumulation. Though not soluble in water, POPs are readily absorbed in fatty tissue, where concentrations can become magnified by up to 70,000 times the background levels. Fish, predatory birds, mammals, and humans are high up the food chain and so absorb the greatest concentrations. When they travel, the POPs travel with them. As a result of these two processes, POPs can be found in people and animals living in regions such as the Arctic, thousands of kilometers from any major POPs source.
Specific effects of POPs can include cancer, allergies and hypersensitivity, damage to the central and peripheral nervous systems, reproductive disorders, and disruption of the immune system. Some POPs are also considered to be endocrine disrupters, which, by altering the hormonal system, can damage the reproductive and immune systems of exposed individuals as well as their offspring; they can also have developmental and carcinogenic effects.
Annex A (Elimination)
Parties must take measures to eliminate the production and use of the chemicals listed under Annex A. Specific exemptions for use or production are listed in the Annex and apply only to Parties that register for them.
Aldrin - Listed under Annex A
A pesticide applied to soils to kill termites, grasshoppers, corn rootworm, and other insect pests, aldrin can also kill birds, fish, and humans. In one incident, aldrin-treated rice is believed to have killed hundreds of shorebirds, waterfowl, and passerines along the Texas Gulf Coast when these birds either ate animals that had eaten the rice or ate the rice themselves. In humans, the fatal dose for an adult male is estimated to be about five grams. Humans are mostly exposed to aldrin through dairy products and animal meats. Studies in India indicate that the average daily intake of aldrin and its byproduct dieldrin is about 19 micrograms per person.
Chlordane - Listed under Annex A
Used extensively to control termites and as a broad-spectrum insecticide on a range of agricultural crops, chlordane remains in the soil for a long time and has a reported half-life of one year. The lethal effects of chlordane on fish and birds vary according to the species, but tests have shown that it can kill mallard ducks, bobwhite quail, and pink shrimp. Chlordane may affect the human immune system and is classified as a possible human carcinogen. It is believed that human exposure occurs mainly through the air, and chlordane has been detected in the indoor air of residences in the US and Japan.
Dieldrin - Listed under Annex A
Used principally to control termites and textile pests, dieldrin has also been used to control insect-borne diseases and insects living in agricultural soils. Its half-life in soil is approximately five years. The pesticide aldrin rapidly converts to dieldrin, so concentrations of dieldrin in the environment are higher than dieldrin use alone would indicate. Dieldrin is highly toxic to fish and other aquatic animals, particularly frogs, whose embryos can develop spinal deformities after exposure to low levels. Dieldrin residues have been found in air, water, soil, fish, birds, and mammals, including humans. Food represents the primary source of exposure to the general population. For example, dieldrin was the second most common pesticide detected in a US survey of pasteurized milk.
Endrin - Listed under Annex A
This insecticide is sprayed on the leaves of crops such as cotton and grains. It is also used to control rodents such as mice and voles. Animals can metabolize endrin, so it does not accumulate in their fatty tissue to the extent that structurally similar chemicals do. It has a long half-life, however, persisting in the soil for up to 12 years. In addition, endrin is highly toxic to fish. When exposed to high levels of endrin in the water, sheepshead minnows hatched early and died by the ninth day of their exposure. The primary route of exposure for the general human population is through food, although current dietary intake estimates are below the limits deemed safe by world health authorities.
Heptachlor - Listed under Annex A
Primarily used to kill soil insects and termites, heptachlor has also been used more widely to kill cotton insects, grasshoppers, other crop pests, and malaria-carrying mosquitoes. It is believed to be responsible for the decline of several wild bird populations, including Canadian Geese and American Kestrels in the Columbia River basin in the US. The geese died after eating seeds treated with levels of heptachlor lower than the usage levels recommended by the manufacturer, indicating that even responsible use of heptachlor may kill wildlife. Laboratory tests have also shown high doses of heptachlor to be fatal to mink, rats, and rabbits, with lower doses causing adverse behavioral changes and reduced reproductive success.
Heptachlor is classified as a possible human carcinogen. Food is the major source of exposure for humans, and residues have been detected in the blood of cattle from the US and from Australia.
Mirex - Listed under Annex A
This insecticide is used mainly to combat fire ants, and it has been used against other types of ants and termites. It has also been used as a fire retardant in plastics, rubber, and electrical goods.
Direct exposure to mirex does not appear to cause injury to humans, but studies on laboratory animals have caused it to be classified as a possible human carcinogen. In studies mirex proved toxic to several plant species and to fish and crustaceans. It is considered to be one of the most stable and persistent pesticides, with a half life of up to 10 years. The main route of human exposure to mirex is through food, particularly meat, fish, and wild game.
Taxaphene - Listed under Annex A
This insecticide is used on cotton, cereal grains, fruits, nuts, and vegetables. It has also been used to control ticks and mites in livestock. Toxaphene was the most widely used pesticide in the US in 1975. Up to 50% of a toxaphene release can persist in the soil for up to 12 years.
For humans, the most likely source of toxaphene exposure is food. While the toxicity to humans of direct exposure is not high, toxaphene has been listed as a possible human carcinogen due to its effects on laboratory animals. It is highly toxic to fish; brook trout exposed to toxaphene for 90 days experienced a 46% reduction in weight and reduced egg viability, and long-term exposure to levels of 0.5 micrograms per liter of water reduced egg viability to zero.
Alpha hexachlorocyclohexane - Listed under Annex A
Chemical identity and properties
CAS No: 319-84-6
Use and production
Although the intentional use of alpha-HCH as an insecticide was phased out years ago, this chemical is still produced as unintentional by-product of lindane. For each ton of lindane produced, around 6-10 tons of the other isomers including alpha- and beta-HCH are created. Large stockpiles of alpha- and beta-HCH are therefore present in the environment.
POPs characteristics of alpha-HCH
Alpha-HCH is highly persistent in water in colder regions and may bioaccumulate and biomagnify in biota and arctic food webs. This chemical is subject to long-range transport, is classified as potentially carcinogenic to humans and adversely affects wildlife and human health in contaminated regions.
Replacement of alpha-HCH
Today, alpha-HCH is only produced unintentionally during the production of lindane. Releases also occur from stockpiles and contaminated sites.
Beta hexachlorocyclohexane - Listed under Annex A
Chemical identity and properties
CAS No: 319-85-7
Use and production
Although the intentional use of beta-HCH as an insecticide was phased out years ago, this chemical is still produced as unintentional by-product of lindane. For each ton of lindane produced, around 6-10 tons of the other isomers including alpha- and beta-HCH are created. Large stockpiles of alpha- and beta-HCH are therefore present in the environment.
POPs characteristics of beta-HCH
Beta-HCH is highly persistent in water in colder regions and may bioaccumulate and biomagnify in biota and arctic food webs. This chemical is subject to long-range transport, is classified as potentially carcinogenic to humans and adversely affects wildlife and human health in contaminated regions.
Replacement of beta-HCH
Today, beta-HCH is only produced unintentionally during the production of lindane. Releases also occur from stockpiles and contaminated sites.
Annex B (Elimination)
Parties must take measures to restrict the production and use of the chemicals listed under Annex B in light of any applicable acceptable purposes and/or specific exemptions listed in the Annex.
DDT - Listed under Annex B (with acceptable purpose for disease vector control)
DDT was widely used during World War II to protect soldiers and civilians from malaria, typhus, and other diseases spread by insects. After the war, DDT continued to be used to control disease, and it was sprayed on a variety of agricultural crops, especially cotton. DDT continues to be applied against mosquitoes in several countries to control malaria. Its stability, its persistence (as much as 50% can remain in the soil 10-15 years after application), and its widespread use have meant that DDT residues can be found everywhere; residual DDT has even been detected in the Arctic.
Perhaps the best known toxic effect of DDT is egg-shell thinning among birds, especially birds of prey. Its impact on bird populations led to bans in many countries during the 1970s. Although its use had been banned in many countries, it has been detected in food from all over the world. Although residues in domestic animals have declined steadily over the last two decades, food-borne DDT remains the greatest source of exposure for the general population. The short-term acute effects of DDT on humans are limited, but long-term exposures have been associated with chronic health effects. DDT has been detected in breast milk, raising serious concerns about infant health.
Perfluorooctane Sulfonic Acid and Sulfonyl Fluoride
Perfluorooctane sulfonic acid (PFOS), its salts and perfluorooctane sulfonyl fluoride (PFOS-F) - Listed under Annex B
Chemical identity and properties
PFOS is a fully fluorinated anion, which is commonly used as a salt or incorporated into larger polymers. PFOS and its closely related compounds, which may contain PFOS impurities or substances that can result in PFOS, are members of the large family of perfluoroalkyl sulfonate substances.
perfluorooctane sulfonic acid (CAS No: 1763-23-1) and its salts
perfluorooctane sulfonyl fluoride (CAS No: 307-35-7)
Use and production
PFOS is both intentionally produced and an unintended degradation product of related anthropogenic chemicals. The current intentional use of PFOS is widespread and includes: electric and electronic parts, fire fighting foam, photo imaging, hydraulic fluids and textiles. PFOS is still produced in several countries.
POPs characteristics of PFOS
PFOS is extremely persistent and has substantial bioaccumulating and biomagnifying properties, although it does not follow the classic pattern of other POPs by partitioning into fatty tissues but instead binds to proteins in the blood and the liver. It has a capacity to undergo long-range transport and also fulfills the toxicity criteria of the Stockholm Convention.
Replacement of PFOS
While alternatives to PFOS are available for some applications, this is not always the case in developing countries where existing alternatives may need to be phased in. For some applications like photo imaging, semi-conductor or aviation hydraulic fluids, technically feasible alternatives to PFOS are not available to date.
List of acceptable purposes and specific exemptions for production and use of PFOS, its salts and PFOS-F
Photo-imaging, photo-resist and anti-reflective coatings for semi-conductor, etching agent for compound semi-conductor and ceramic filter, aviation hydraulic fluids, metal plating (hard metal plating) only in closed-loop systems, certain medical devices (such as ethylene tetrafluoroethylene copolymer (ETFE) layers and radio-opaque ETFE production, in‑vitro diagnostic medical devices, and CCD colour filters), fire‑fighting foam, insect baits for control of leaf-cutting ants from Atta spp. and Acromyrmex spp.
Photo masks in the semiconductor and liquid crystal display (LCD) industries, metal plating (hard metal plating, decorative plating), electric and electronic parts for some colour printers and colour copy machines, insecticides for control of red imported fire ant, and termites, chemically driven oil production, carpets, leather and apparel, textiles and upholstery, paper and packaging, coatings and coating additives, rubber and plastics.
Annex C (Unintentional Production)
Parties must take measures to reduce the unintentional releases of chemicals listed under Annex C with the goal of continuing minimization and, where feasible, ultimate elimination.
Hexachlorobenzene (HCB) - Listed under Annex A and Annex C
First introduced in 1945 to treat seeds, HCB kills fungi that affect food crops. It was widely used to control wheat bunt. It is also a byproduct of the manufacture of certain industrial chemicals and exists as an impurity in several pesticide formulations.
When people in eastern Turkey ate HCB-treated seed grain between 1954 and 1959, they developed a variety of symptoms, including photosensitive skin lesions, colic, and debilitation; several thousand developed a metabolic disorder called porphyria turcica, and 14% died. Mothers also passed HCB to their infants through the placenta and through breast milk. In high doses, HCB is lethal to some animals and, at lower levels, adversely affects their reproductive success. HCB has been found in food of all types. A study of Spanish meat found HCB present in all samples. In India, the estimated average daily intake of HCB is 0.13 micrograms per kilogram of body weight.
Pentachlorobenzene (PeCB) - Listed under Annex A and Annex C
Chemical identity and properties
PeCB belongs to a group of chlorobenzenes that are characterized by a benzene ring in which the hydrogen atoms are substituted by one or more chlorines.
CAS No: 608-93-5
Use and production
PeCB was used in PCB products, in dyestuff carriers, as a fungicide, a flame retardant and as a chemical intermediate e.g. previously for the production of quintozene. PeCB might still be used as an intermediate. PeCB is also produced unintentionally during combustion, thermal and industrial processes. It also present as impurities in products such as solvents or pesticides.
POPs characteristics of of PeCB
PeCB is persistent in the environment, highly bioaccumulative and has a potential for long-range environmental transport. It is moderately toxic to humans and very toxic to aquatic organisms.
Replacement of of PeCB
The production of PeCB ceased some decades ago in the main producer countries as efficient and cost-effective alternatives are available. Applying Best Available Techniques and Best Environmental Practices would significantly reduce the unintentional production of PeCB.
Polychlorinated dibenzofurans (PCDF)
Polychlorinated dibenzofurans (PCDF) - Listed under Annex C
These compounds are produced unintentionally from many of the same processes that produce dioxins, and also during the production of PCBs. They have been detected in emissions from waste incinerators and automobiles. Furans are structurally similar to dioxins and share many of their toxic effects. There are 135 different types, and their toxicity varies. Furans persist in the environment for long periods, and are classified as possible human carcinogens. Food, particularly animal products, is the major source of exposure for humans. Furans have also been detected in breast-fed infants.
Polychlorinated dibenzo-p-dioxins (PCDD)
Polychlorinated dibenzo-p-dioxins (PCDD) - Listed under Annex C
These chemicals are produced unintentionally due to incomplete combustion, as well during the manufacture of pesticides and other chlorinated substances. They are emitted mostly from the burning of hospital waste, municipal waste, and hazardous waste, and also from automobile emissions, peat, coal, and wood. There are 75 different dioxins, of which seven are considered to be of concern. One type of dioxin was found to be present in the soil 10 - 12 years after the first exposure.
Dioxins have been associated with a number of adverse effects in humans, including immune and enzyme disorders and chloracne, and they are classified as possible human carcinogens. Laboratory animals given dioxins suffered a variety of effects, including an increase in birth defects and stillbirths. Fish exposed to these substances died shortly after the exposure ended. Food (particularly from animals) is the major source of exposure for humans.
Polychlorinated biphenyls (PCB)
Polychlorinated biphenyls (PCB) - Listed under Annex A with specific exemptions and under Annex C
These compounds are used in industry as heat exchange fluids, in electric transformers and capacitors, and as additives in paint, carbonless copy paper, and plastics. Of the 209 different types of PCBs, 13 exhibit a dioxin-like toxicity. Their persistence in the environment corresponds to the degree of chlorination, and half-lives can vary from 10 days to one-and-a-half years.
PCBs are toxic to fish, killing them at higher doses and causing spawning failures at lower doses. Research also links PCBs to reproductive failure and suppression of the immune system in various wild animals, such as seals and mink.
Large numbers of people have been exposed to PCBs through food contamination. Consumption of PCB-contaminated rice oil in Japan in 1968 and in Taiwan in 1979 caused pigmentation of nails and mucous membranes and swelling of the eyelids, along with fatigue, nausea, and vomiting. Due to the persistence of PCBs in their mothers' bodies, children born up to seven years after the Taiwan incident showed developmental delays and behavioral problems. Similarly, children of mothers who ate large amounts of contaminated fish from Lake Michigan showed poorer short-term memory function. PCBs also suppress the human immune system and are listed as probable human carcinogens.