What Are POPs?

Persistent organic pollutants (POPs) are carbon containing chemical compounds that, to a varying degree, resist photochemical, biological and chemical degradation. POPs are often halogenated and characterise by low water solubility and high lipid solubility, leading, together with their persistence, to bioacumulation in fatty tissues. They are also semi-volatile, a property which permits these compounds either to vaporise or to be adsorbed on atmospheric particles. They therefore undergo long range transport in air and water from warmer to colder regions of the world.

Although many different chemicals, both natural and anthropogenic (i.e. produced by man), may be defined as POPs, 12 POPs, all chlorine-containinig organic compounds, have been chosen as priority pollutants by the United Nations Environment Programme (UNEP) for their impact on human health and environment. The twelve POPs include many of the first generation organochlorine insecticides, e.g. DDT, aldrin, industrial chemical products, e.g. PCBs (polychlorinated biphenyls) or, unwanted by-products such as dioxins and furans.

UNEP 12 POPs

Most POPs may persist in the environment for periods of several years and may bioconcentrate up to ten thousands fold. These properties of unusual high persistence and semi-volatility, coupled with other characteristics, have resulted in the presence of POPs all over the world, even in regions where they have never been used. POPs are ubiquitous. They have been measured on every continent, at sites representing every major climatic zone and geographic region throughout the world. These include remote regions, where no significant local sources exist and the only reasonable explanation for their presence is long-range transport from other parts of the globe. POPs have been found, on a global scale, in soils, sediments, in the fat of fish and terrestrial animals, as well as in human breast milk. Some of the highest levels have been recorded in the polar areas of both the hemispheres.

Humans are generally exposed to POPs through the ingestion of food. A growing body of scientific evidence associates human exposure to individual POPs with cancer, neurotoxic, behavioural, reproductive effects, immutoxicity and other effects. The mechanism for many of these effects appears to be through disruption of the human endocrine system. Humans appear to be extraordinary sensitive to these chemicals during fetal development.(WFPHA, World Federation of Public Health Association, 2000).

POPs are linked by a growing body of evidence to reproductive failure, deformities, malfunctions in fish and wild life. Studies from the Great Lakes environment revealed that a dozen of Great Lakes predators as eagles, cormorants, trouts, minks, turtles and others, suffered significant health impacts including population decline and reproductive dysfunction, eggshell thinning, metabolic changes, deformities and birth defects, cancers, behavioural changes, abnormally functioning thyroids and other hormone system dysfunction, immune suppression, feminisation of males and masculinisation of females.(WFPHA, 2000).

Read more about POPs, Download "The Ritter Report": Persistent Organic Pollutants Assessment Report, IOMC, Dec. 1995, 76K/145K, English. (htm file)

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