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Conceptual Model for Dioxin in the Environment

Conceptual Model for Dioxin in the Environment. Dwain Winters Director Dioxin Policy Project Office of Pollution Prevention and Toxics 202 260 8558 Winters.dwain@epa.gov. Dioxin-Like Compounds. Cl. Cl. O. Cl. Cl. Cl. Cl. Cl. Cl. Cl. Cl. Cl. Cl. O. O. Cl. Cl.

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Conceptual Model for Dioxin in the Environment

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  1. Conceptual Model for Dioxin in the Environment Dwain Winters Director Dioxin Policy Project Office of Pollution Prevention and Toxics 202 260 8558 Winters.dwain@epa.gov PBT Monitoring Strategy Workshop

  2. Dioxin-Like Compounds Cl Cl O Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl O O Cl Cl 2,3,7,8-Tetrachlorodibenzo-p-dioxin 3,3',4,4',5,5'-Hexachlorobiphenyl 2,3,7,8-Tetrachlorodibenzofuran Furans 135 congeners 10 toxic Dioxins 75 congeners 7 toxic PCBs 209 congeners 12 toxic 2,3,7,8-TCDD 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD 1,2,3,4,6,7,8,9-OCDD 2,3,7,8-TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF 1,2,3,4,6,7,8,9-OCDF 3,3',4,4'-TeCB 3,3',4,4',5-PeCB 3,3',4,4',5,5'-HxCB PBT Monitoring Strategy Workshop

  3. Dioxin-Like Compounds • Semivolatile • Lipophilic • Hydrophobic • Persistent • Bioaccumulating • Toxics PBT Monitoring Strategy Workshop

  4. Trace Levels --- Highly Toxic • Soil, Food --- PPT • Water --- PPQ • Air --- fg/m3 • Human Serum ---PPT • Intake --- 1pg/kg/d TEQ • Upper Bound Cancer Risk 1x10-3 • Non-Cancer MOE < 10 PBT Monitoring Strategy Workshop

  5. 95% of Background Exposure From Commercial Food Supply Vegetable fat Soil ingestion Soil dermal contact Other meats Freshwaterfish and Poultry shellfish 6% Pork 5% 19% Marine fish and shellfish Beef 7% 14% 1% Inhalation 4% 16% Eggs 21% Milk Dairy PBT Monitoring Strategy Workshop

  6. 20th Century Trend PBT Monitoring Strategy Workshop

  7. PBT Monitoring Strategy Workshop

  8. PBT Monitoring Strategy Workshop

  9. Major US Dioxin Sources 1987 1995 2004

  10. Reservoir Sources • Old releases of dioxins that are temporarily stored in • environmental compartments to later be reintroduced • into the circulating environment • Contribute as much as 50% of general population • Dioxin-like PCBs more than a third of total risk • Fish likely to be dominated by sediment reservoirs. PBT Monitoring Strategy Workshop

  11. Sources and Pathways to Human Exposures SOURCES DEPOSITION FOOD SUPPLY TRANSPORT Reentrainment Runoff Erosion

  12. Average Annual Dioxin Air Concentration National Dioxin Ambient Monitoring Networkyear 2000

  13. Dioxin Environmental Mobility • Dioxins are less mobile than Hg or the more volatile PCBs. • Dioxins do not appear to exhibit global retort, or • strong “grasshopper” effect. • Dioxins are continually exchanged among media and • should be viewed as a complex system of stocks and flows PBT Monitoring Strategy Workshop

  14. Fluxes amongdioxin reservoirs

  15. Monitoring Activities • Air monitoring (NDAMN) provides direct near term measure • of source reduction in air emissions. (EPA) • Food provides the most direct measure of current exposure. (FDA, USDA, and EPA) • Blood serum best long term measure of reducing risk. (CDC) • Baseline monitoring needs include: • National soil survey • National sediment survey. PBT Monitoring Strategy Workshop

  16. Monitoring and Modeling • A Major Opportunity for Analytical Tool Development • 2000 Release Inventory • 2000 NDAMN Data • Air transport Models PBT Monitoring Strategy Workshop

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