For the last decades, awareness has been growing about the threats posed to human health and the global environment by the ever-increasing release in the natural environment of synthesized chemicals.
Mounting evidence of damage to human health and the environment has focused the attention of the international community on a category of substances referred to as Persistent Organic Pollutants (POPs). Persistent Organic Pollutants are very toxic. They are characterized by strong persistence to degradation in the environment for years or decades. Chemicals and compounds of this group have the potential to travel great distances from the source of release through various media (air, water). POPs released in one part of the world can, through a repeated process of evaporation and deposit, be transported through the atmosphere to regions far away from the original source.
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. During pregnancy and breastfeeding POPs are often passed on to the next generations.
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.
The realization of these threats led a number of countries to introduce policies and legal and regulatory instruments to manage an increasing number of these substances. However, because of POPs persistence and propensity to undergo transboundary movement, countries began to seek bi-lateral and regional multinational co-operative actions.
In May 2001 these efforts successfully resulted in adoption under the name of Stockholm Convention on Persistent Organic Pollutants (POPs) of a global, legally binding agreement to reduce and eliminate releases of POPs to the environment. Its aim is to protect human health and the environment from POPs. Originally, it concentrates upon the twelve POPs, which are considered as most dangerous to the environment and human health, the so-called “Dirty Dozen”. The Stockholm Convention on Persistent Organic Pollutants enters into force on 17 May 2004.
12 POPs regulated by the Stockholm Convention (“Dirty Dozen”):
1. Aldrin – a pesticide applied to soils to kill termites, grasshoppers, corn rootworm and other insect pests.
2. Dieldrin – used principally to control termites and textile pests, dieldrin has also been use to control insect-borne diseases and insects living in agricultural soils.
3. Chlordane – used extensively to control termites and as a broad-spectrum insecticide on a range of agricultural crops.
4. Heptachlor – primarily employed 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.
5. DDT – the best known of the POPs, it was widely used during World War II to protect soldiers and civilians from malaria, typhus, and other diseases spread by insects. It continues to be applied against mosquitoes in several countries to control malaria.
6. Endrin – this insecticide is sprayed on the leaves of crops such as cotton and grains. It is also used to control mice, voles and other rodents.
7. Hexachlorobenzene (HCB) – HCB kills fungi that affect food crops. It is also released as by-product during the manufacture of certain chemicals and as a result of the processes that give rise to dioxins and furans.
8. Mirex – this insecticide is applied mainly to combat fire ants and other types of ants and termites. It has also been used as a fire retardant in plastics, rubber, and electrical goods.
9. Toxaphene – this insecticide, also called camphechlore, is applied to cotton, cereal grains, fruits, nuts, and vegetables. It has also been used to control ticks and mites in livestock.
II. Industrial substances
Polichlorinated biphenyls (PCBs) – these compounds are employed in industry as heat exchange fluids, in electric transformers and capacitors, and as additives in paint, carbonless copy paper, sealants and plastics.
1. Dioxins – these chemicals are produced unintentionally due to incomplete combustion, as well as during the manufacture of certain pesticides and other chemicals. In addition, certain kinds of metal recycling and pulp and paper bleaching can release dioxins. Dioxins have also been found in automobile exhaust, tobacco smoke and wool and coal smoke.
2. Furans – these compounds are produced unintentionally from the same processes that release dioxins, and they are also found in commercial mixtures of PCBs.
Source: UNDP/MEP Project "Initial Assistance To The Republic Of Kazakhstan To Meet Its Obligations Under The Stockholm Convention On Persistent Organic Pollutants (POPS)"
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