Contaminants: Budgets and Behaviour Case Studies

PCBs have been commercially produced for various applications since the 1930s. The known global mass production of PCBs virtually ceased in 1984, except for the production in the former Soviet Union, which ended in 1993. Worldwide, more than 1.3 million tonnes of PCBs have been intentionally produced (Breivik et al. 2002a). Dated sediment core studies have indicated that the temporal contamination pattern has mirrored the production and use of these contaminants (e.g. Christensen and Lo, 1986; Gevao et al. 1997). The environmental occurrence of these compounds in coastal zones and elsewhere are thus believed to be a direct result of the historical intentional production, consecutive use and disposal or accidental releases from products or materials containing PCBs (Breivik et al. 2002b). In addition, incidental or unwanted formation (de novo synthesis) is also reported to contribute to the environmental burden of PCBs (e.g. Brown et al. 1995). Even though global mass production has ended, PCBs are still frequently detected in environmental samples. This may in part be attributed to the long environmental half-lives of PCBs (Sinkkonen and Paasivirta, 2000) and in part caused by the potential long lifetime of products or materials containing PCBs (resulting in a significant time delay between production and cessation of primary emissions). The environmental concerns caused by PCBs in coastal zones are primarily a result of the affinity for PCBs to partition into the organic phases of suspended particles and bottom sediments as well as into the lipids of aquatic biota. This is problematic for several reasons. A primary issue of concern is that human exposure to PCBs tends to be significantly controlled by consumption of seafood, such as fatty fish. A second issue of long-term concern is the potential remobilisation of PCBs from contaminated sediments (Larsson, 1985), representing a potential threat for further uptake in biota for decades to come because of the long response time of sediments to loading reductions. In this document, a brief overview is Clx 2’ 3’