Temps de lecture :4 minutes
Purpose and issues
Persistent organic pollutants (POPs) are complex molecules which, unlike other pollutants, are not defined by their chemical composition (since they are so varied) but rather by four properties they have in common. They possess toxic properties, resist degradation, bioaccumulate, and are transported through air, water and migratory species across international boundaries. The definition of POPs is therefore strictly regulatory. All POPs are organic compounds; they are often simply termed pesticides, PCBs, or dioxins (see below).
Persistent organic pollutants bioaccumulate in terrestrial and aquatic ecosystems. Notably, they contaminate humans through the food chain, and pass from mother to child via the placenta or breast milk. Because of their semi-volatile make-up, they can also travel long distances once released into the environment, going through several cycles of evaporation, atmospheric transfer, and condensation. The Arctic ecosystems and indigenous communities are particularly at risk because of the biomagnification of persistent organic pollutants.
To limit the risks that discharges and emissions of POPs pose for human health and the environment, the United Nations Environment Programme (UNEP) decided to provide the international community with a specific executive instrument: the Stockholm Convention on Persistent Organic Pollutants (22 May 2001). This Convention aims to reduce and/or eliminate production and emission of 12 POPs. The 1998 Aarhus Protocol (concluded within the framework of the Geneva Convention on Long-range Transboundary Air Pollution) bans four other POPs (chlordecone, hexabromobiphenyl, hexachlorocyclohexane and polycyclic aromatic hydrocarbons).
The Convention concerns pollutants used as pesticides, heat exchange and dielectric fluids, and synthetic intermediaries (hexachlorobenzene, endrin, mirex, toxaphene, chlordane, heptachlor, DDT, aldrin, dieldrin, PCBs) or other industrial chemicals (dioxins, furans, PCBs).
It provides a framework for monitoring production, import, export, use, and elimination of these chemicals.
The Convention distinguishes between:
– POPs arising from intentional production (the first ten chemicals listed, commonly used as pesticides);
– POPs arising from unintentional production (dioxins and furans);
– POPs contained in stockpiles and wastes.
The goal of the Convention is to bring about definitive elimination of POPs. The text outlines the right of States to refuse a hazardous substance which may pose a threat to human health and/or the environment, even where there is a lack of full scientific certainty. For these reasons, the Convention is seen as an example of international adherence to the precautionary principle.
Effects and application
The Stockholm Convention is a legal-binding instrument (bans on production and import, etc.). It includes some acceptable purposes for certain substances, however. (For example, disease vector control use of DDT is acceptable in areas affected by malaria-carrying mosquitoes). However, the goal is to eliminate use of these substances entirely. Parties making use of the “acceptable purpose” clause (such as for DDT) must prove that they have no other safe, effective, or affordable solutions available to them.
There is also a provision for “specific exemption” (including a register of specific exemptions which may be modified at any time). For example, production of dieldrin is eliminated; however its use in agricultural operations is a specific exemption.
The European Community has adopted several legislative texts in application of the Stockholm Convention, notably, Regulation (EC) No 850/2004 of the European Parliament and of the Council of 29 April 2004 on persistent organic pollutants. This regulation bans the production, placing on the market, and use of substances listed in Annex 1 (a reprise of the Stockholm Convention). Moreover, EU member states must lay down rules on effective, proportionate, and dissuasive penalties to encourage effective application of the Convention. The 12 substances listed in the Convention are strictly regulated at the European level.
Nevertheless, to cite the example of PCB alone, 1.2 billion tonnes have been produced worldwide and some 400 million tonnes remain in the environment. Sale of PCBs has been completely banned in France since 1987.
A national plan for decontamination and disposal of PCB-containing equipment was implemented in 2003 (following the 2001 transposition of a 1996 EU directive), with a target date of 31 December 2010. The French Environment and Energy Management Agency (ADEME) produced an inventory of 545,610 PCB-contaminated pieces of equipment, including capacitors and transformers of the national electricity utility (EDF). However, the problem of PCB-contaminated waste is alive and well, as demonstrated by pollution of the Rhône and its tributaries. There is still widespread contamination of sediment and fish, the latter reporting PCB levels of up to 59 pg/g (the WHO recommends a maximum of 8pg/g for dioxins and PCBs in fish destined for human consumption). The source of this contamination is still unknown, however associations point out that the factory performing PCB decontamination of the above-mentioned 545,610 pieces of equipment disposes of wastewater in the regional main sewer and is located upstream from one of the Rhône’s tributaries.
According to article 7 of the Stockholm Convention, each Party shall develop a national implementation plan detailing how it will fulfil its obligations under the Convention. The Plan shall be transmitted to the Conference of the Parties (COP) within two years of the date on which the Convention enters into force for the Party in question. Each Party shall review and update its implementation plan on a periodic basis.
The Convention also provides for listing of additional POPs, at the initiative of the Parties to the Convention. The Persistent Organic Pollutants Review Committee defines scientific criteria and rules for listing new pollutants, using a precautionary approach. During the COP-3 in Dakar, 2007, the Parties expressed a desire to add 5 POPs to the list, and the POP Review Committee set up a task force to assess the risks of 5 other chemicals (1).