Conceptual model for dioxin in the environment
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Conceptual Model for Dioxin in the Environment. Dwain Winters Director Dioxin Policy Project Office of Pollution Prevention and Toxics 202 260 8558 [email protected] 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

Conceptual Model for Dioxin in the Environment

Dwain Winters

Director Dioxin Policy Project

Office of Pollution Prevention and Toxics

202 260 8558

[email protected]

PBT Monitoring Strategy Workshop


Dioxin like compounds
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


Dioxin like compounds1
Dioxin-Like Compounds

  • Semivolatile

  • Lipophilic

  • Hydrophobic

  • Persistent

  • Bioaccumulating

  • Toxics

PBT Monitoring Strategy Workshop


Trace levels highly toxic
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


95 of background exposure from commercial food supply
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


20 th century trend
20th Century Trend

PBT Monitoring Strategy Workshop




Major US Dioxin Sources

1987

1995

2004


Reservoir sources
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


Sources and pathways to human exposures
Sources and Pathways to Human Exposures

SOURCES

DEPOSITION

FOOD

SUPPLY

TRANSPORT

Reentrainment

Runoff

Erosion


Average Annual Dioxin Air Concentration

National Dioxin Ambient Monitoring Networkyear 2000


Dioxin environmental mobility
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


Fluxes among dioxin reservoirs
Fluxes amongdioxin reservoirs


Monitoring activities
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


Monitoring and modeling
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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