Persistent organic pollutant
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2008-06-13T23:40:57Z
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'''Persistent organic pollutants''' ('''POP'''s) are organic compounds that are resistant to environmental degradation through [[chemical decomposition|chemical]], [[biodegradation|biological]], and [[photolysis|photolytic]] processes.<ref name="ritter">Ritter L, Solomon KR, and Forget J, Stemeroff M, and O'Leary C. [http://www.chem.unep.ch/pops/ritter/en/ritteren.pdf Persistent organic pollutants: An Assessment Report on: DDT, Aldrin, Dieldrin, Endrin, Chlordane, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, Polychlorinated Biphenyls, Dioxins and Furans]. Prepared for The International Programme on Chemical Safety (IPCS), within the framework of the Inter-Organization Programme for the Sound Management of Chemicals (IOMC). Retrieved on [[September 16]], [[2007]].</ref> Because of this, they have been observed to [[persistence|persist]] in [[the environment]], to be capable of long-range transport, [[bioaccumulate]] in human and animal [[Biological tissue|tissue]], [[biomagnification|biomagnify]] in food chains,<ref name="ritter"/> and to have potential significant impacts on [[human health]] and the environment.
In May [[1995]], the [[United Nations Environment Programme]] Governing Council (GC) decided to begin investigating POPs, initially beginning with a short list of the following twelve POPs, known as the 'dirty dozen'<ref name="thedirtydozen">The 12 chemicals that the Stockholm Convention focuses on eliminating or reducing[http://www.unido.org/doc/29428]. Retrieved on [[December 17]], [[2007]]</ref>: [[aldrin]], [[chlordane]], [[DDT]], [[dieldrin]], [[endrin]], [[heptachlor]], [[hexachlorobenzene]], [[mirex]], [[polychlorinated biphenyls]], [[Polychlorinated dibenzodioxins|polychlorinated dibenzo-p-dioxins]], [[dibenzofuran|polychlorinated dibenzofurans]], and [[toxaphene]].<ref name="ritter"/>
Since then, this list has generally been accepted to include such substances as [[carcinogen]]ic [[polycyclic aromatic hydrocarbons]] (PAHs) and certain [[brominated flame-retardant]]s, as well as some [[organometallic compound]]s such as [[tributyltin]] (TBT).
The groups of compounds that make up POPs are also classed as PBTs ('''P'''ersistent, '''B'''ioaccumulative and '''T'''oxic) or TOMPs ('''T'''oxic '''O'''rganic '''M'''icro '''P'''ollutants.)
Many POPs are currently or were in the past used as [[pesticide]]s. Others are used in industrial processes and in the production of a range of goods such as [[solvent]]s, [[polyvinyl chloride]], and [[pharmaceutical]]s.<ref name="ritter"/> Though there are a few natural sources of POPs, most POPs are created by humans in industrial processes, either intentionally or as byproducts.<ref name="ritter"/>
== Chemical properties ==
Some of the chemical characteristics of POPs include low water [[solubility]], high lipid solubility, semi-[[volatility]]<ref name="ritter"/>, and high [[molecular mass]]es. POPs with molecular weights lower than 236 g/mol are less toxic, less persistent in the [[natural environment|environment]], and have more reversible effects than those with higher molecular masses.<ref name="ritter"/> POPs are frequently [[halogenated]], usually with [[chlorine]].<ref name="ritter"/> The more chlorine groups a POP has, the more resistant it is to being broken down over time.<ref name="ritter"/> One important factor of their chemical properties such as lipid solubility results in the ability to pass through biological [[Lipid bilayer|phospholipid membrane]]s and [[bioaccumulation|bioaccumulate]] in the [[fatty tissue]]s of living organisms.<ref name="ritter"/>
== Long-range transport ==
POPs released to the environment have been shown to travel vast distances from their original source. Due to their chemical properties, many POPs are semi-volatile and insoluble. These compounds are therefore unable to transport directly through the environment.{{Fact|date=September 2007}} The indirect routes include attachment to [[particulate matter]], and through the [[food chain]]. The chemicals' semi-volatility allows them to travel long distances through the [[atmosphere]] before being deposited.<ref name="ritter"/> Thus POPs can be found all over the world, including in areas where they have never been used and remote regions such as the middle of oceans and [[Antarctica]].<ref name="ritter"/> The chemicals' semi-volatility also means that they tend to volatilize in hot regions and accumulate in cold regions, where they tend to condense and stay.<ref name="ritter"/> [[Polychlorinated biphenyl|PCBs]] have been found in [[precipitation]].<ref name="ritter"/>
The ability of POPs to travel great distances is part of the explanation for why countries that banned the use of specific POPs are no longer experiencing a decline in their concentrations; the wind may carry chemicals into the country from places that still use them.<ref>United Nations Economic Commission for Europe (May 1996), [http://www.unece.org/spot/s01.htm Interview with Mr. Lars Nordberg]. Unece.org. Retrieved on [[September 18]], [[2007]].</ref>
== Health concerns ==
Exposure to POPs can take place through diet, environmental exposure, or accidents.<ref name="ritter"/> POP exposure can cause death and illnesses including disruption of the [[endocrine system|endocrine]], [[reproductive system|reproductive]], and [[immune system]]s; neurobehavioral disorders; and [[cancer]]s possibly including [[breast cancer]].<ref name="ritter"/>
The lipid solubility of POPs allows them to [[bioaccumulate]] in fatty tissues of animals.<ref name="ritter"/> Many of the first generation [[organochlorine]] [[insecticide]]s such as DDT were particularly noted for this characteristic.<ref name="ritter"/>
A study published in [[2006]] indicated a link between [[blood serum]] levels of POPs and [[diabetes]].<ref name="Lee">Lee DH, Lee IK, Song K, Steffes M, Toscano W, Baker BA, and Jacobs DR Jr. (2006), [http://care.diabetesjournals.org/cgi/content/full/29/7/1638 A Strong Dose-Response Relation Between Serum Concentrations of Persistent Organic Pollutants and Diabetes]. ''Diabetes Care'', 29:1638-1644. PMID 16801591. Retrieved on [[September 16]], [[2007]].</ref> Individuals with elevated levels of persistent organic pollutants ([[DDT]], [[dioxins]], [[Polychlorinated biphenyl|PCB]]s and [[Chlordane]], among others) in their body were found to be up to 38 times more likely to be [[insulin resistance|insulin resistant]] than individuals with low levels of these pollutants, though the study did not demonstrate a cause and effect relationship.<ref name="Lee"/> As most exposure to POPs is through consumption of [[animal fat]]s, study participants with high levels of serum POPs are also very likely to be consumers of high amounts of animal fats, and thus the consumption of the fats themselves, or other associated factors may be responsible for the observed increase in insulin resistance. Another possibility is that insulin resistance causes increased accumulation of POPs. Among study participants, [[obesity]] was associated with diabetes only in people who tested high for these pollutants. These pollutants are accumulated in animal fats, so minimizing consumption of animal fats may reduce the risk of diabetes.<ref name="Living on Earth">{{cite web |year = 2006 | url = http://www.loe.org/shows/segments.htm?programID=06-P13-00050&segmentID=2 | title = Living on Earth: POPsible Nightmare | publisher=Living on Earth and World Media Foundation| accessdate = 2007-09-16}}</ref> According to the [[US Department of Veterans Affairs]], [[Diabetes mellitus type 2|type 2 diabetes]] is on the list of presumptive diseases associated with exposure to [[Agent Orange]] (which contained the POP dioxin) in the [[Vietnam War]].<ref name="Lee"/>
==See also ==
* [[Center for International Environmental Law]] ([[CIEL]])
* [[Food chain]]
* [[International POPs Elimination Network]] ([[IPEN]])
* [[Stockholm Convention]]
== References ==
{{Reflist}}
== External links ==
* [http://www.ewg.org/reports/cheminventory/ Environmental Working Group - POPs/PBT investigation]
* [http://www.greenpeace.org/international/campaigns/toxics/chemicals-out-of-control/ Greenpeace: Chemicals out of control]
* [http://www.pesticideinfo.org The PAN Pesticides Database]
* [http://www.pan-international.org/ Pesticide Action Network (PAN) is a network of over 600 NGOs worldwide]
* [http://www.pops.int/ Stockholm Convention on Persistent Organic Pollutants]
* [http://www.panda.org/campaign/detox/ WWF: Detox Campaign]
* [http://www.monarpop.at/ POP monitoring in the Alpine region (Europe)]
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[[Category:Persistent organic pollutants| ]]
[[Category:Environmental issues]]
[[Category:Environmental effects of pesticides]]
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