What are POPs?:
Persistent Organic Pollutants (POPs) are a group of chemicals that are very toxic and can cause cancer and other adverse health effects. POPs are persistent in the environment and travel vast distances via air and water. POPs are organic chemical compounds which bioaccumulate in animals and humans. These pollutants are primarily the products and by-products of human industrial processes.The initial list of twelve POPs include :
- industrial chemicals like polychlorinated biphenyls (PCBs) used in transformer oils;
- pesticides like DDT, endrin, dieldrin, aldrin, chlordane, toxaphene, heptachlor, mirex, hexachlorobenzene (HCB); and
- unwanted wastes like dioxins and furans.
Other chemicals are currently being assessed for inclusion in the POPs list.
'Poisons Without Passports'
When POPs are released to the environment, they can travel through air and water to regions far from their original sources. POPs concentrate in living organisms to levels where they can injure human health and the environment. POPs do their damage even in regions like the Arctic, far from where they are used or released.
POPs Common Characteristics:
As a general rule, POPs have a number of common properties:
- POPs are persistent in the environment. They resist degradation or breakdown through physical, chemical, or biological processes;
- POPs generally are semi-volatile. They evaporate relatively slowly but when they enter the air, they travel long distances on air currents. They return to earth in rain and snow in the colder areas of the globe, resulting in their accumulation in regions such as the Arctic, thousands of kilometres away from their original sources;
- POPs generally have low water solubility (they do not dissolve readily in water) and high lipid (fat) solubility (they do dissolve easily in fats and oils). Persistent substances with these properties bioaccumulate in fatty tissues of living organisms. In the environment, concentrations of these substances can increase by factors of many thousands or millions as they move up the food chain; and
- POPs have the potential to injure humans and other organisms even at the very low concentrations at which they are now found in the environment, wildlife and humans. Some POPs in extraordinarily small amounts can disrupt normal biological functions, including the activity of natural hormones and other chemical messengers, triggering a cascade of potentially harmful effects.