abs

Exposure and Human Health Reassessment of 2,3,7,8-

3,95

Tetrachlorodibenzo-p-Dioxin (TCDD)- and Related Compounds -

660

stron

Part I: Estimating Exposure to Dioxin-Like Compounds - Volume

4: Site-Specific Assessment Procedures

5917

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

2000

rok

CONTENTS

1. INTRODUCTION . 1-1

1.1. BACKGROUND . 1-1

1.2. DESCRIPTION OF DIOXIN-LIKE COMPOUNDS 1-2

1.3. TOXICITY EQUIVALENCY FACTORS 1-3

1.4. OVERALL COMMENTS ON THE USE OF VOLUME IV OF THE DIOXIN EXPOSURE

DOCUMENT . 1-6

1.5. NOTES ON THE USE OF PROCEDURES IN VOLUME IV . 1-6

REFERENCES FOR CHAPTER 1 1-10

2. ESTIMATING EXPOSURES AND RISKS 2-1

2.1. INTRODUCTION 2-1

2.2. EXPOSURE EQUATION 2-2

2.3. CANCER AND NON-CANCER RISK ASSESSMENT . 2-4

2.3.1. Cancer Risk Assessment 2-4

2.3.2. Evaluating Non-Cancer Effects . 2-6

2.4. THE TOXIC EQUIVALENCY PROCEDURE 2-6

2.5. PROCEDURE FOR ESTIMATING EXPOSURE 2-7

2.6. STRATEGY FOR DEVISING EXPOSURE SCENARIOS 2-10

2.7. EXPOSURE PATHWAYS AND PARAMETERS . 2-13

2.7.1. Soil Related Exposures 2-14

2.7.1.1. Soil Ingestion 2-14

2.7.1.2. Soil Dermal Contact . 2-15

2.7.2. Vapor and Dust Inhalation . 2-17

2.7.3. Water Ingestion . 2-19

2.7.4. Ingestion of Terrestrial Food Products 2-19

2.7.4.1. Derivation of the Contact Fractions for Beef, Milk, Chicken, Eggs, Vegetables, and Fruits .

2-23

2.7.4.2. Beef Ingestion . 2-24

2.7.4.3. Dairy Ingestion . 2-25

2.7.4.4. Chicken Ingestion . 2-25

2.7.4.5. Egg Ingestion 2-25

2.7.4.6. Vegetable and Fruit Ingestion 2-26

2.7.5. Fish Ingestion . 2-26

REFERENCES FOR CHAPTER 2 2-29

3. EVALUATING ATMOSPHERIC RELEASES OF DIOXIN-LIKE COMPOUNDS FROM

COMBUSTION SOURCES . 3-1

3.1. INTRODUCTION 3-1

3.2. ESTIMATING THE EMISSIONS OF DIOXIN-LIKE COMPOUNDS FROM ANTHROPOGENIC

COMBUSTION SOURCES 3-2

3.2.1. A Strategy for Generating Emission Factors . 3-4

3.2.2. Use of Homologue and Congener-Specific Profiles to Estimate Emission Factors 3-7

3.2.2.1 Using Congener Profiles to Convert Total CDD/F . 3-8

3.2.2.2 Estimating Congener-Specific Emissions when no Congener Profiles are Available . 3-8

3.2.3. Estimation of Emissions of Dioxin-Like Compounds from the Hypothetical Incinerator 3-9

3.2.4. Estimation of the Vapor Phase/Particle Phase Partitioning of Emissions of Dioxin-Like

Compounds . 3-10

3.2.4.1. Vapor Phase/Particulate Phase Inferences from Stack Measurements . 3-10

3.2.4.2. Discussion of Vapor/Particle Ratios Derived from Stack Testing Methods 3-13

3.2.4.3. Vapor/Particle Partitioning of CDD/Fs from Ambient Air Sampling . 3-16

3.2.4.4. Discussion of the Vapor/Particle Partitioning in Ambient Air Sampling Studies 3-23

3.2.4.5. Junge-Pankow Model of Particle/Gas Distribution in Ambient Air . 3-23

3.2.4.6. Modeling the Vapor/Particle (V/P) Distribution of CDD/Fs . 3-26

3.2.4.7. Comparison of Measured and Modeled Vapor/Particle Distributions for CDD/Fs . 3-29

3.2.4.8. Discussion of Monitored and Modeled Results for CDD/Fs . 3-31

3.2.4.9. Discussion of Vapor/Particle Partitioning . 3-33

3.2.5. Estimation of the Concentration of Dioxin-Like Compounds in Incineration Ash . 3-34

3.3. AIR DISPERSION/DEPOSITION MODELING OF THE STACK GAS EMISSIONS OF DIOXIN-

LIKE COMPOUNDS . 3-36

3.3.1. Basic Physical Principles Used to Estimate Atmospheric Dispersion/Deposition of Stack

Emissions 3-37

3.3.2. Estimation of Dry Surface Deposition Flux . 3-38

3.3.3. Estimation of the Particle Size Distribution in the Stack Emissions . 3-42

3.3.4. Estimation of Wet Deposition Flux . 3-44

3.3.5. Using ISCST3 to Model Emissions of Particles and Vapors 3-46

3.4. RESULTS OF THE AIR DISPERSION MODELING OF CONGENERSPECIFIC EMISSIONS

FROM THE HYPOTHETICAL ORGANIC WASTE INCINERATOR . 3-47

3.5. REVIEW OF PROCEDURES FOR ESTIMATING SITE-SPECIFIC IMPACTS FROM A STACK

EMISSION SOURCE . 3-50

REFERENCES FOR CHAPTER 3 3-52

4. ESTIMATING EXPOSURE MEDIA CONCENTRATIONS . 4-1

4.1. INTRODUCTION 4-1

4.2. BACKGROUND FOR SOLUTION ALGORITHMS 4-1

4.3. ALGORITHMS FOR THE SOIL CONTAMINATION SOURCE

CATEGORY 4-7

4.3.1. Surface Water and Sediment Contamination . 4-8

4.3.2. Exposure Site Soil Concentrations . 4-23

4.3.3. Vapor- and Particle-Phase Air Concentrations . 4-31

4.3.4. Biota Concentrations . 4-40

4.3.4.1. Fish Concentrations . 4-40

4.3.4.2. Vegetation Concentrations 4-49

4.3.4.3. Beef and Milk Concentrations 4-68

4.3.4.4. Chicken and Egg Concentrations . 4-78

4.3.5. Specific Cases of Soil Contamination . 4-84

4.3.5.1. Landfills Receiving Ash from Municipal Waste Incinerators . 4-84

4.3.5.2. Land Application of Sludge from Pulp and Paper Mills . 4-92

4.3.5.3. Sites Studied in the National Dioxin Study 4-94

4.4. ALGORITHMS FOR THE STACK EMISSION SOURCE CATEGORY . 4-97

4.4.1. Steady-State Soil Concentrations 4-98

4.4.2 Surface Water Impacts . 4-100

4.5. ALGORITHMS FOR THE EFFLUENT DISCHARGE SOURCE CATEGORY 4-105

4.5.1. The Simple Dilution Model 4-107

REFERENCES FOR CHAPTER 4 . 4-116

5. DEMONSTRATION OF METHODOLOGY . 5-1

5.1. INTRODUCTION 5-1

5.2. STRATEGIES FOR DEVISING EXPOSURE SCENARIOS . 5-2

5.3. EXAMPLE EXPOSURE SCENARIOS 5-8

5.4. EXAMPLE COMPOUNDS 5-12

5.5. SOURCE TERMS . 5-13

5.6. RESULTS . 5-19

5.6.1. Observations Concerning Exposure Media Concentrations . 5-20

5.6.2. Observations Concerning LADD Exposure Estimates . 5-27

5.7. HEALTH RISK DEMONSTRATIONS . 5-30

REFERENCES FOR CHAPTER 5 5-31

6. USER CONSIDERATIONS 6-1

6.1. INTRODUCTION 6-1

6.2. CATEGORIZATION OF METHODOLOGY PARAMETERS 6-1

6.3. SENSITIVITY ANALYSIS . 6-7

6.3.1. Limitations of the Sensitivity Analysis Exercises 6-7

6.3.2. Methodology Description and Parameter Assignments 6-10

6.3.3. Results 6-23

6.3.3.1. Estimation of Vapor-Phase and Particle-phase Air Concentrations Distant from a Site of

Soil Contamination . 6-23

6.3.3.2. Estimation of Soil Erosion Impacts to Nearby Sites of Exposure . 6-25

6.3.3.3. Estimation of Soil Erosion Impacts to Nearby Surface Water Bodies 6-27

6.3.3.4. Vapor-Phase Transfers and Particle-Phase Depositions to Above Ground Vegetation 6-29

6.3.3.5. Estimation of Below Ground Vegetation Concentrations . 6-33

6.3.3.6. Beef Fat Concentration Estimation in the Soil Contamination and Stack Emission Source

Categories . 6-34

6.3.3.7. Impact of Distance from the Stack Emission Source on Concentrations in Soil, Vegetables,

and Beef Fat . 6-37

6.3.3.8. Water and Fish Concentrations Resulting from Effluent Discharges 6-38

6.3.3.9. Water and Fish Concentrations Resulting from Stack Emissions . 6-39

6.3.4. Key Trends from the Sensitivity Analysis Testing 6-40

6.4. MASS BALANCE CONSIDERATIONS 6-42

REFERENCES FOR CHAPTER 6 6-48

7. MODEL COMPARISONS AND MODEL VALIDATIONS 7-1

7.1. INTRODUCTION 7-1

7.2. MODEL COMPARISON EXERCISES 7-3

7.2.1. Evaluation of Alternative Air-to-Leaf Modeling Approaches . 7-3

7.2.1.1. The Field Data 7-4

7.2.1.2. Model Descriptions and Application to the Field Data . 7-4

7.2.1.3. Results and Discussion of the Air-to-Leaf Model Comparison Exercise . 7-9

7.2.1.4. Literature Comparisons of Air-to-Plant Modeling Approaches . 7-14

7.2.2. An Alternate Modeling Approach for Estimating Water Concentrations Given a Steady Input

Load from Overland Sources . 7-16

7.2.3. Estimating Fish Tissue Concentrations Based on Water Column Concentrations Rather than

Bottom Sediment Concentrations . 7-19

7.2.4. Other Modeling Approaches and Considerations for Air Concentrations Resulting from Soil

Volatilization 7-24

7.2.5. Alternate Models for Estimating Plant Concentrations from Soil Concentrations 7-37

7.2.6. Alternate Modeling Approaches for Estimating Beef and Milk Concentrations 7-40

7.3. MODEL VALIDATION EXERCISES . 7-50

7.3.1. The Impact of Dioxin Soil Contamination to Nearby Soils 7-50

7.3.2. Soil Concentrations and Concurrent Concentrations in Bottom Sediments and Fish . 7-52

7.3.3. Other Bottom Sediment Concentration Data 7-57

7.3.4. Data on Water Concentrations of Dioxin-Like Compounds . 7-58