Hexachlorocyclohexanes in Arctic and Antarctic Marine Ecosystems

Abstract

Pesticides are a group of chemicals made for the purpose of killing or otherwise deterring “pest” species. The word pesticides may refer to insecticides, fungicides, herbicides or other pest control formulations. Introduced in 1940s, organochlorine pesticides (OCPs) were widely used as insecticides in agriculture and pest control until research and public concern regarding the hazards of their use and adverse effects in the environment led to government restrictions and bans. Two International legally binding instruments have been negotiated and concluded: the Protocol to the regional United Nations Economic Commission for Europe Convention on Long Range Transboundary Air Pollution (CLRTAP) on Persistent Organic Pollutants (POPs), opened for signature in June 1998 and entered into force on 23 October 2003 and the Stockholm Convention on POPs, opened for signature in May 2001 and entered into force on 17 May 2004. Both these agreements identify POPs that should be banned and/or phased out or whose use or emissions should be restricted, they include industrial chemicals and by-products such as PCBs, hexachlorobenzene, dioxins and furans, and a number of OCPs such as aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex and toxaphene. All together are often called the “dirty dozen” (Stockholm Convention, 2004). The hexachlorocyclohexanes (HCHs) are covered by the UNECE Protocol but not the Stockholm Convention. For several listed substances, some limited use is allowed, for example DDT for fighting malaria. Despite the actions of these two Conventions, POPs are still present at high levels in the polar regions and will require vigilant action in the continuing implementation of the Conventions to prevent further contamination of these rich and productive ecosystems. OCPs are organic chemical substances which possess a particular combination of physical and chemical properties and once released into the environment they remain intact for long periods of time (from weeks to decades). They are persistent that is they resist to environmental degradation through chemical, biological and photolytic processes. They are toxic to both humans and wildlife and accumulate in the fatty tissue of living organisms (bioaccumulation), and are found at higher concentrations at higher levels of the food webs (biomagnification). They are subjected to long range transport (LRT) and can be found in remote regions, including Arctic and Antarctica, where they have never been used or produced (i.e.: Su et al., 2006; Bargagli, 2008; Corsolini, 2008; Riget et al., 2010; Donaldson et al., 2010)