Editorial
PCDD / PCDF
Editorial
Dioxins-
Furans-
And N o End
The 15th international meeting on Organohalogen Compounds ("Dioxin '95") has just ended in Edmonton, Alberta, Canada (August 21 -25). This series of annual meetings has consistently drawn 600 - 800 and more participants for the last ten years. From many points of view PCDD/PCDF are model compounds for modern organic micropollutants. They are essentially by-products of combustion and chemical industry and have never been manufactured for any useful purpose. They represent a complex mixture of congeners and isomers which, coupled with the need for sensitive detection, has proven to be a formidable analytical challenge. Modern environmental trace analysis is measured against dioxin analysis. Several members of these groups of compounds are biologically active at extremely low concentrations; they are persistent and bioaccumulating, and have a long toxicokinetic half-life. These characteristics have induced an intensive research effort which pushed the frontiers of environmental science far ahead. Some examples are the extremely low detection limit (fg) and separation requirements. The use of isotopically labelled standards allows unprecedented accuracy and precision, even at low levels. The basic features of environmental distribution of semi-volatile organic compounds (SVO) were elucidated for PCDD/PCDF and PCBs as were aerial plant uptake, entry into the food chain and, ultimately, human exposure. Intensive efforts are underway for risk assessment, risk characterization and toxicological assessment.
ESPR- Environ. Sci. & Pollut. Res. 2 (2) 67 (1995) 9 ecomed publishers, D-86899 Landsberg, Germany
What is left to do? We still need technological ways of reducing dioxin emissions from some sources and, perhaps, identify hitherto unknown sources. We need worldwide quantification and comparison of PCDD/PCDF levels in different compartments and media including background levels. The importance of brominated and mixed bromino/chloro dioxins and furans is not yet fully evaluated. The concept of toxic equivalency factors (TEF) has proven very useful but they need refining, particularly for PCBs. We need human data to strengthen EPA's assessment of 2,3,7,8-substituted dioxins and furans being probable carcinogens. Non-cancer endpoints require more attention (e.g. immunosuppressive, hormonal and reproductive effects), and the question of threshold dose needs clarification. An interesting toxicological development is the recognition that naturally occurring compounds for instance in vegetables - show dioxin-like activity. Funding of dioxin research is declining (e.g. in Germany). The conclusion is that careful international information exchange of data and concepts is even more important to avoid duplication of work. We hope the Dioxin meetings planned for the following years will help. "Dioxin '96" will take place in Amsterdam, and 1997, 1998, 1999 the meetings will be held in Indianapolis, Stockholm and Milan.
Otto Hutzinger Editor-in-Chief
67
PCDD / PCDF
Editorial
Dioxins-
Furans-
And N o End
The 15th international meeting on Organohalogen Compounds ("Dioxin '95") has just ended in Edmonton, Alberta, Canada (August 21 -25). This series of annual meetings has consistently drawn 600 - 800 and more participants for the last ten years. From many points of view PCDD/PCDF are model compounds for modern organic micropollutants. They are essentially by-products of combustion and chemical industry and have never been manufactured for any useful purpose. They represent a complex mixture of congeners and isomers which, coupled with the need for sensitive detection, has proven to be a formidable analytical challenge. Modern environmental trace analysis is measured against dioxin analysis. Several members of these groups of compounds are biologically active at extremely low concentrations; they are persistent and bioaccumulating, and have a long toxicokinetic half-life. These characteristics have induced an intensive research effort which pushed the frontiers of environmental science far ahead. Some examples are the extremely low detection limit (fg) and separation requirements. The use of isotopically labelled standards allows unprecedented accuracy and precision, even at low levels. The basic features of environmental distribution of semi-volatile organic compounds (SVO) were elucidated for PCDD/PCDF and PCBs as were aerial plant uptake, entry into the food chain and, ultimately, human exposure. Intensive efforts are underway for risk assessment, risk characterization and toxicological assessment.
ESPR- Environ. Sci. & Pollut. Res. 2 (2) 67 (1995) 9 ecomed publishers, D-86899 Landsberg, Germany
What is left to do? We still need technological ways of reducing dioxin emissions from some sources and, perhaps, identify hitherto unknown sources. We need worldwide quantification and comparison of PCDD/PCDF levels in different compartments and media including background levels. The importance of brominated and mixed bromino/chloro dioxins and furans is not yet fully evaluated. The concept of toxic equivalency factors (TEF) has proven very useful but they need refining, particularly for PCBs. We need human data to strengthen EPA's assessment of 2,3,7,8-substituted dioxins and furans being probable carcinogens. Non-cancer endpoints require more attention (e.g. immunosuppressive, hormonal and reproductive effects), and the question of threshold dose needs clarification. An interesting toxicological development is the recognition that naturally occurring compounds for instance in vegetables - show dioxin-like activity. Funding of dioxin research is declining (e.g. in Germany). The conclusion is that careful international information exchange of data and concepts is even more important to avoid duplication of work. We hope the Dioxin meetings planned for the following years will help. "Dioxin '96" will take place in Amsterdam, and 1997, 1998, 1999 the meetings will be held in Indianapolis, Stockholm and Milan.
Otto Hutzinger Editor-in-Chief
67
