Levels and trends of dioxins, PCBs, and other POPs in abiotic compartments

Abstract

Studies reporting on levels of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCB), and other persistent organic pollutants (POPs) in the air, soil, sediment, and surface water are available from the 1970s to the present. While typically focused regionally, these studies provide important information on the evolution of the distribution and occurrence worldwide of environmental contamination attributed predominantly to human activity. This chapter summarizes monitoring work conducted during the past four decades that have contributed to our understanding of levels and trends in the abiotic environment. This includes a summary of available environmental data from the past two decades describing the current understanding of background conditions and global cycling of POPs. Data are summarized at a continental level for Africa, Asia/Pacific, Europe, North America and South America, and the polar regions. The results confirm the early views of the preeminent scientist in this field, Dr. Otto Hutzinger, who first suggested a “pulse” of highly persistent compounds entering the environment beginning in the 1930s and 1940s, peaking in the 1960s and 1970s, and gradually declining to the present time. This trend, however, does not yet apply to emerging POPs or to some regions of the world where long-range transport processes and monitoring work are evident only more recently. Overall, the distributions and levels of POPs continue to behave as predicted by Dr. Hutzinger; environmental levels of classical industrial chlorinated compounds are generally higher in the northern hemisphere than in the southern hemisphere, and levels are declining worldwide with the possible exception of PCBs and in remote locations where global cycling is finally extending its influence. Dr. Hutzinger’s pioneering research over the past half-century laid the foundation for ongoing improvements in laboratory analysis and monitoring and interpretation of complex data sets, which continue to close the knowledge gap and improve our understanding of POPs in the air, soil, sediment, and water around the world.