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The Stockholm Convention
The Stockholm Convention, held in May 2001, focuses on eliminating or reducing releases of 12 POPs, the so-called "Dirty Dozen”. These 12 chemicals include aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, and toxaphene used principally as pesticides, two industrial chemicals polychlorinated biphenyls and hexachlorobenzene used in industry but also produced unintentionally together with dioxins and furans. Over 150 countries signed the Convention, which will enter into force shortly after the ratification by the fiftieth country, which is expected in 2004. The Global Environmental Facility (GEF) is the designated interim financial mechanism for the Stockholm Convention.
The Stockholm Convention derives global action to focuses on legal and administrative measures to prohibit the production and use of the intentionally produced and used nine pesticides, and elimination and reduction of the unintentionally POPs chemicals. The latter (Dioxins, Furans, PCBs, HCB) are formed and released from thermal processes involving organic matter and chlorine as a result of incomplete combustion or chemical reactions. The following industrial sources categories have the potential for comparatively high formation and release of these chemicals to the environment: Waste incinerators, cement kilns firing hazardous waste, production of pulp using chlorine bleachers, metallurgical industry, fossil fuel and wood burning boilers, textile and leather dying (with chloranil) and finishing (with alkaline extraction), and waste oil refineries.
Domestic waste that contains aromatic precursors such as lignin, polystyrene, PVC and plastics containing vinyl chloride resin would generate, depending on process conditions, dioxins at a temperature approaching 350-600Co. In municipal solid waste incinerators, chloroform gives rise to formation ofhexachlorobenzene (HCB) and eventually the destruction of these will form dioxins and furans.
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