Acknowledgments .............................................. xvii
Authors ....................................................... xix
Acronyms ...................................................... xxi
Introduction .................................................. xxv
Chapter 1 Historical Use of Chlorinated Solvents and Their
Stabilizing Compounds ................................ 1
1.1 History of Chlorinated Solvents ............................ 1
1.1.1 Major Applications of Chlorinated Solvents .......... 4
1.1.1.1 Chlorinated Solvents in Historical or
Current Use ................................ 4
1.1.1.2 Cold Cleaning ............................. 10
1.1.1.3 Vapor Degreasing .......................... 11
1.1.1.4 Dry Cleaning .............................. 17
1.1.1.5 Off-Site Solvent Recycling ................ 22
1.2 Role of Solvent Stabilizers ............................... 24
1.2.1 Types of Solvent Stabilizers and Solvent
Breakdown .......................................... 24
1.2.2 Consequences of Solvent Breakdown .................. 25
1.2.2.1 Operator Safety ........................... 25
1.2.2.2 Off-Spec Work ............................. 27
1.2.2.3 Production Line Shutdown .................. 27
1.2.3 Stability of the Major Solvents .................... 28
1.2.3.1 Performance Criteria for Solvent
Stabilizers in Various Applications ....... 29
1.2.3.2 Selection of Solvent Stabilizers .......... 30
1.2.4 Causes of Solvent Breakdown ........................ 31
1.2.4.1 Oxidation ................................. 31
1.2.4.2 Ultraviolet Light Breakdown ............... 32
1.2.4.3 Thermal Breakdown ......................... 33
1.2.4.4 Acid Breakdown ............................ 34
1.2.4.5 Solvent Deterioration Catalyzed by
Metals and Metal Salts .................... 35
1.2.5 Testing Solvent Stability and Performance .......... 38
1.2.5.1 Acid Acceptance Value ..................... 39
1.2.5.2 Aluminum Scratch Test ..................... 40
1.2.6 Identifying Solvent Stabilizers Used in
Chlorinated Solvents ............................... 40
1.2.6.1 Solvent Stabilizer Chemicals .............. 44
1.2.6.2 Antioxidants .............................. 47
1.2.6.3 Light Inhibitors .......................... 47
1.2.6.4 Thermal Stabilizers ....................... 48
1.2.6.5 Acid Acceptors ............................ 48
1.2.6.6 Metal Inhibitors .......................... 49
1.2.7 Fate of Stabilizers in Industrial Applications
and Solvent Recycling .............................. 54
1.2.7.1 Boiling-Point Differences ................. 54
1.2.7.2 Solubility Differences .................... 58
1.2.7.3 Vapor Pressure Differences ................ 61
1.2.7.4 Carbon Adsorption ......................... 61
1.2.7.5 Thermal Stability ......................... 62
1.2.7.6 Replenishing Solvent Stabilizers .......... 63
Acknowledgments ................................................ 65
Bibliography ................................................... 65
Chapter 2 1,4-Dioxane: Chemistry, Uses, and Occurrence ........ 75
2.1 Chemistry of 1,4-Dioxane .................................. 75
2.2 History of 1,4-Dioxane Production ......................... 79
2.2.1 1,4-Dioxane Production for Commercial
Applications ....................................... 79
2.2.2 Impurities and Stabilizers of 1,4-Dioxane .......... 80
2.3 Direct Uses of 1,4-Dioxane ................................ 81
2.3.1 Cellulose Acetate Membrane Production for Reverse
Osmosis and Kidney Dialysis Filters ................ 83
2.3.2 Liquid Scintillation Cocktails ..................... 83
2.3.3 Tissue Preservative in Histology and Other
Laboratory Microscopy Methods ...................... 85
2.3.4 Printing Inks and Paints and Related Uses .......... 86
2.3.4.1 Inks and Printing Operations .............. 86
2.3.4.2 Historical Restoration .................... 86
2.3.4.3 Painting, Coating, and Paint Stripping .... 86
2.3.5 Flame Retardant Production ......................... 87
2.3.6 Rubber and Plastics Industry ....................... 87
2.3.7 Aircraft Deicing Fluid and Antifreeze .............. 88
2.3.8 Adhesives .......................................... 88
2.3.9 Polyurethane Materials for Medical Devices ......... 89
2.3.10 Solvent-Based Cleaning Agents ...................... 89
2.3.11 Ether Supplements in Fuels ......................... 90
2.4 1,4-Dioxane as a By-Product of Manufacturing .............. 90
2.4.1 Ethoxylated Surfactants ............................ 90
2.4.1.1 Personal Care Products: Detergents,
Shampoos, and Sundries .................... 91
2.4.1.2 Personal Care Products: Cosmetics ......... 93
2.4.1.3 1,4-Dioxane in Contraceptive Sponges and
Spermicidal Lubricants .................... 95
2.4.1.4 1,4-Dioxane in Polyethylene Glycol ........ 95
2.4.1.5 1,4-Dioxane in Glyphosphate Herbicides
(Accord®, Roundup®, Rodeo®, Vision®) ...... 96
2.4.1.6 1,4-Dioxane in Pesticides ................. 96
2.4.2 Terephthalate Esters (Polyester) and Resins ........ 97
2.4.3 1,4-Dioxane as a By-Product of Petroleum Refining
and Gasoline Antiknock Agent ....................... 98
2.5 1,4-Dioxane in Food ....................................... 99
2.6 1,4-Dioxane Use in the Pharmaceutical Industry ........... 101
2.7 Detections of 1,4-Dioxane in Ambient Surface Water,
Groundwater, and Air ..................................... 102
2.8 Estimated Releases of 1,4-Dioxane to the Environment ..... 103
2.8.1 1,4-Dioxane in Wastewater ......................... 104
2.8.2 1,4-Dioxane in Landfills .......................... 105
Bibliography .................................................. 106
Chapter 3 Environmental Fate and Transport of Solvent-
Stabilizer Compounds ............................... 115
3.1 Fate and Transport Processes ............................. 115
3.1.1 Atmospheric Fate and Transport Processes .......... 116
3.1.2 Volatilization from Dry Soil ...................... 116
3.1.3 Volatilization from Water ......................... 119
3.1.3.1 Henry's Law .............................. 119
3.1.3.2 Mass Transfer Rates from Water to Air:
Flux Density ............................. 120
3.1.4 Atmospheric Fate of Stabilizer Compounds .......... 122
3.1.4.1 Photolysis ............................... 122
3.1.4.2 Photo-Oxidation in the Atmosphere ........ 126
3.1.4.3 Photo-Oxidation in Water ................. 129
3.2 Surface-Water Fate and Transport Processes ............... 129
3.2.1 Hydrolysis ........................................ 130
3.2.2 Acid Dissociation Potential ....................... 131
3.3 Subsurface Fate and Transport Processes .................. 133
3.3.1 Aqueous Solubility of Stabilizer Compounds and
Stabilizer-Solvent-Waste Mixtures ................. 134
3.3.2 Adsorption ........................................ 137
3.3.2.1 Soil Properties Affecting Adsorption ..... 138
3.3.2.2 Molecular Properties Affecting
Adsorption ............................... 139
3.3.2.3 Distribution Coefficients and Sorption
Isotherms ................................ 139
3.3.2.4 Organic Carbon Partition Coefficient,
Koc ...................................... 141
3.3.2.5 Predicting Кoc from Kow, the Octanol/
Water Partition Coefficient .............. 142
3.3.2.6 Effect of Surface Oxides on Sorption ..... 144
3.3.2.7 Competitive Sorption ..................... 144
3.3.2.8 Use of Laboratory Batch Tests to
Measure Kd in Soil ....................... 146
3.3.2.9 Sorption of Vapor-Phase 1,4-Dioxane ...... 147
3.3.2.10 High-Strength 1,4-Dioxane Solutions May
Cause Clay Swelling ...................... 147
3.3.3 Subsurface Vapor-Phase Transport .................. 149
3.3.4 Biodegradability of Solvent-Stabilizer
Compounds ......................................... 150
3.3.4.1 Predicting Biodegradability .............. 154
3.3.4.2 Biodegradability of 1,4-Dioxane:
Laboratory Studies ....................... 156
3.3.4.3 Synopsis of 1,4-Dioxane
Biodegradability Studies ................. 161
3.4 Laboratory, Field, and Modeling Studies of 1,4-Dioxane
Mobility ................................................. 169
3.4.1 Laboratory Studies ................................ 169
3.4.2 Field Studies ..................................... 169
3.4.3 Modeling 1,4-Dioxane Transport .................... 171
3.5 Diffusive Transport of 1,4-Dioxane and Storage in
Fine-Grained Soils ....................................... 173
Bibliography .................................................. 180
Chapter 4 Sampling and Laboratory Analysis for Solvent
Stabilizers ........................................ 191
4.1 The Flawed Paradigm of Analyte Lists ..................... 191
4.2 Sample Collection, Preservation, and Handling for
Analysis of 1,4-Dioxane .................................. 193
4.2.1 Sampling for 1,4-Dioxane in Water ................. 193
4.2.1.1 Passive-Diffusion Bag Samplers ........... 195
4.2.1.2 Rigid Porous Polyethylene Samplers ....... 195
4.2.1.3 Snap Sampler ............................. 196
4.2.1.4 Gore Sampler ............................. 198
4.2.2 Sampling for 1,4-Dioxane in Air and Landfill
Gas ............................................... 198
4.2.3 Personnel Air Monitoring .......................... 199
4.3 Sample Preparation ....................................... 199
4.3.1 Purge and Trap .................................... 199
4.3.2 Heated Purge and Trap ............................. 200
4.3.3 Equilibrium Headspace Extraction .................. 200
4.3.4 Vacuum Distillation ............................... 201
4.3.5 Azeotropic Distillation ........................... 202
4.3.6 Sample Extraction ................................. 202
4.3.6.1 Liquid-Liquid Extraction ................. 202
4.3.6.2 Solid-Phase Extraction ................... 204
4.4 Laboratory Methods for the Analysis of 1,4-Dioxane by
GC-MS .................................................... 209
4.4.1 Gas Chromatography ................................ 210
4.4.1.1 Methods in Gas Chromatography ............ 211
4.4.1.2 Selecting Chromatographic Columns for
1,4-Dioxane Analysis ..................... 211
4.4.2 Detectors in Gas Chromatography ................... 212
4.4.2.1 Mass Spectroscopy ........................ 213
4.4.2.2 Mass Spectroscopy and 1,4-Dioxane ........ 214
4.5 Environmental Protection Agency Methods for Analysis of
1,4-Dioxane .............................................. 214
4.5.1 Environmental Protection Agency Method 8015B ...... 215
4.5.2 Environmental Protection Agency Method 8260B ...... 216
4.5.3 Environmental Protection Agency Method 8260C ...... 217
4.5.4 Environmental Protection Agency Method 8261A ...... 217
4.5.5 Environmental Protection Agency Method 8270C-
Extracted Semivolatile Organic Compounds by Gas
Chromatography-Mass Spectroscopy .................. 219
4.5.6 Environmental Protection Agency Method 1624-
Isotope-Dilution Gas Chromatography-Mass
Spectroscopy ...................................... 219
4.5.7 Environmental Protection Agency Method 522-
Solid-Phase Extraction and Gas Chromatography-
Mass Spectroscopy with Selective Ion Monitoring ... 222
4.6 Laboratory Safety for 1,4-Dioxane Handling and
Instrument Cleaning ...................................... 222
Acknowledgments ............................................... 223
Bibliography .................................................. 223
Chapter 5 The Toxicology of 1,4-Dioxane ...................... 229
5.1 Toxicokinetics ........................................... 229
5.2 Toxicity Studies in Humans ............................... 232
5.3 Toxicology Studies in Laboratory Animals ................. 232
5.3.1 Acute and Short-Term Toxicity Studies (<1 Month
Exposure) ......................................... 232
5.3.2 Subchronic and Chronic Toxicity Studies ........... 238
5.3.3 Mechanistic Toxicology Studies .................... 246
5.3.3.1 Genotoxicity ............................. 246
5.3.3.2 Initiation/Promotion Studies ............. 247
5.3.3.3 Mechanistic Studies Evaluating Mode of
Action for Carcinogenicity ............... 252
5.4 Summary of Noncancer Health Effects ...................... 254
5.5 Characterization of Cancer Potential ..................... 255
5.5.1 Summary of Human and Animal Data .................. 255
5.5.2 Weight-of-Evidence Evaluation ..................... 255
5.5.3 Mode of Action .................................... 256
5.6 1,4-Dioxane Toxicology and Risk Assessment ............... 257
Acknowledgments ............................................... 258
Bibliography .................................................. 258
Chapter 6 Regulation and Risk Assessment of 1,4-Dioxane ...... 263
6.1 Drinking Water Regulations for 1,4-Dioxane ............... 264
6.1.1 Federal ........................................... 265
6.1.2 Basis for State Regulations or Guidelines:
Colorado, California, Connecticut, and Michigan ... 270
6.1.2.1 Colorado's 1,4-Dioxane Standard .......... 271
6.1.2.2 California's Notification Level .......... 273
6.1.2.3 Connecticut's Comparison Value for
1,4-Dioxane .............................. 275
6.1.2.4 Michigan's Proposed Maximum Contaminant
Level .................................... 275
6.1.3 Need for Regulation: Occurrence of 1,4-Dioxane
in Drinking Water ................................. 277
6.2 Water Quality Regulations: Protection of Ecological
Receptors ................................................ 279
6.2.1 National Pollution Discharge Elimination System
Regulations ....................................... 279
6.2.2 Toxicity of 1,4-Dioxane to Aquatic Organisms ...... 279
6.2.3 Toxicity of 1,4-Dioxane to Aquatic and
Terrestrial Organisms ............................. 281
6.2.4 Regulating 1,4-Dioxane Discharges from
Groundwater Cleanup Sites ......................... 281
6.2.5 Regulating 1,4-Dioxane in Industrial Wastewater
Discharges and Recycled Water ..................... 284
6.2.5.1 Industrial Wastewater Discharge
Regulations .............................. 286
6.2.5.2 Recycled Water Regulations ............... 287
6.3 Air Quality Regulations: Occupational Health and Safety
and Ambient Air Quality .................................. 287
6.3.1 Occupational Health and Safety Regulations for
1,4-Dioxane ....................................... 288
6.3.2 Emissions Standards and Air Quality Regulations
for 1,4-Dioxane ................................... 288
6.4 Regulating 1,4-Dioxane in Food, Pharmaceuticals,
Cosmetics, and Sundries .................................. 292
6.4.1 Food Regulations .................................. 292
6.4.1.1 1,4-Dioxane in Dietary Supplements ....... 292
6.4.1.2 1,4-Dioxane in Ice Cream ................. 293
6.4.1.3 1,4-Dioxane in Gluten-Free Bread ......... 293
6.4.1.4 1,4-Dioxane in Food-Packaging
Materials ................................ 293
6.4.1.5 The Delaney Clause ....................... 294
6.4.2 Regulation of 1,4-Dioxane in Pharmaceutical
Products .......................................... 294
6.4.3 Regulation of 1,4-Dioxane in Cosmetics and
Shampoos .......................................... 295
6.4.4 California Proposition 65 ......................... 297
6.5 Risk Assessments of 1,4-Dioxane .......................... 298
6.5.1 Overview of Risk-Assessment Process and Data
Requirements ...................................... 298
6.5.2 Exposure Pathways and Routes ...................... 299
6.5.3 1,4-Dioxane Toxicity Data Used in Risk
Assessments ....................................... 299
6.5.4 Risk from Dermal Exposure to 1,4-Dioxane .......... 302
6.5.5 Risk from Inhalation Exposure to 1,4-Dioxane ...... 306
6.5.5.1 Lactational Transfer Following
Occupational Exposure .................... 307
6.5.5.2 Inhalation Risk from Showering in
1,4-Dioxane Contaminated Water ........... 307
6.5.6 Risk of 1,4-Dioxane Oral Ingestion in Drinking
Water, Food, and Drugs ............................ 310
6.5.7 Relative Risks of Solvent Stabilizers ............. 310
Acknowledgment ................................................ 314
Bibliography .................................................. 314
Chapter 7 Remediation Technologies ........................... 327
7.1 Vapor-Phase Transfer ..................................... 327
7.1.1 Air Stripping ..................................... 327
7.1.2 Accelerated Remediation Technologies, LLC
In-Well System .................................... 328
7.1.3 Pervaporation ..................................... 329
7.1.4 Summary ........................................... 330
7.2 Sorption ................................................. 330
7.2.1 Adsorptive Media .................................. 331
7.2.2 Activated Carbon .................................. 331
7.2.3 Organoclays ....................................... 332
7.2.4 Palladium-111 ..................................... 332
7.2.5 Summary ........................................... 333
7.3 Natural Attenuation ...................................... 333
7.3.1 Evidence of the Effectiveness of Natural
Attenuation ....................................... 333
7.3.2 Diffusion into Immobile Porosity .................. 333
7.3.3 North Carolina Example ............................ 334
7.3.4 Summary ........................................... 336
7.4 Ultraviolet Photolysis ................................... 336
7.5 Phytoremediation ......................................... 337
7.5.1 Bench-Scale Tests ................................. 337
7.5.2 Mathematical Modeling ............................. 338
7.5.3 Greenhouse and Field Studies ...................... 339
7.5.4 Summary ........................................... 339
7.6 Bioremediation ........................................... 339
7.6.1 Mixed Bacterial Cultures .......................... 340
7.6.1.1 Actinomycete Culture ..................... 340
7.6.1.2 Indigenous Soil Microbes ................. 340
7.6.1.3 Degradation of Tetrahydrofuran and
1,4-Dioxane Together ..................... 341
7.6.1.4 Kinetics of Cometabolism ................. 342
7.6.2 Bacteria Genus: Rhodococcus ....................... 342
7.6.3 Bacteria Genus: Pseudonocardia .................... 342
7.6.3.1 Degradation of Multiple Ether
Pollutants ............................... 342
7.6.3.2 Degradation of 1,4-Dioxane ............... 345
7.6.4 Gasotrophic Bacteria: Cometabolic
Biodegradation .................................... 345
7.6.5 Bioreactors and Biobarriers ....................... 346
7.6.6 Anaerobic Bacteria ................................ 348
7.6.7 Fungi ............................................. 349
7.6.8 Enhancing Biodegradability with In Situ Chemical
Oxidation ......................................... 350
7.6.9 Bacteria Summary .................................. 351
7.7 Chemical Oxidation ....................................... 351
7.7.1 Hydrogen Peroxide and Ozone - Еx Situ ............. 352
7.7.2 Hydrogen Peroxide and Ozone - In Situ ............. 354
7.7.3 Hydrogen Peroxide and Ultraviolet Light ........... 357
7.7.4 Hydrogen Peroxide and Ferrous Iron ................ 357
7.7.5 Persulfate ........................................ 358
7.7.6 Permanganate ...................................... 360
7.7.7 Photocatalytic Oxidation .......................... 360
7.7.8 Ozonation ......................................... 361
7.7.9 Sonochemical Oxidation ............................ 362
7.7.10 Chemical Oxidation Summary ........................ 363
Bibliography .................................................. 363
Chapter 8 Case Studies of 1,4-Dioxane Releases, Treatment,
and Drinking Water Contamination ................... 369
8.1 Superfund Site at Seymour, Indiana ....................... 369
8.1.1 Contaminant Distribution and Hydrogeology ......... 370
8.1.2 Risk Management ................................... 371
8.1.3 Treatment ......................................... 372
8.1.4 Discussion ........................................ 373
8.2 Solvent Services Site, San Jose, California .............. 373
8.2.1 Treatment ......................................... 374
8.2.2 1,4-Dioxane Detection and Laboratory Challenges ... 375
8.2.3 Regulation ........................................ 377
8.2.4 Discussion ........................................ 377
8.3 Pall/Gelman Sciences Inc., Ann Arbor, Michigan ........... 378
8.3.1 Wastewater Disposal ............................... 378
8.3.2 Geologic Setting .................................. 379
8.3.3 Delineating 1,4-Dioxane Contamination ............. 380
8.3.4 Regulation ........................................ 381
8.3.5 Treatment ......................................... 382
8.3.6 Legal Actions ..................................... 384
8.4 Former American Beryllium Company, Tallevast, Florida .... 386
8.4.1 Geologic Setting .................................. 386
8.4.2 Site History ...................................... 387
8.4.3 Regulatory Response: Remediation and Water
Supply Replacement ................................ 391
8.4.3.1 UV Oxidation Pilot Treatability Study .... 391
8.4.3.2 Ozone and Peroxide Oxidation Pilot
Study .................................... 393
8.4.3.3 In Situ Biostimulation and
Bioaugmentation Treatability Study ....... 393
8.4.4 Community Response ................................ 394
8.4.5 Discussion ........................................ 396
8.5 Stanford Linear Accelerator Center Groundwater Cleanup
Sites .................................................... 396
8.5.1 SLAC Site History ................................. 397
8.5.2 Geologic and Hydrologic Setting ................... 397
8.5.3 Contaminant Releases .............................. 398
8.5.3.1 Remediation at Former Hazardous Waste
Storage Area ............................. 400
8.5.3.2 Former Solvent Underground Storage Tank
Area ..................................... 400
8.5.4 Possible Reasons for 1,4-Dioxane Removal by
Granular Activated Carbon ......................... 401
8.6 1,4-Dioxane and Orange County Water District OCWD
Groundwater Replenishment System ......................... 403
8.6.1 History of the Orange County Water District
Groundwater Replenishment System .................. 404
8.6.2 1,4-Dioxane Detected at Water Factory 21 .......... 405
8.6.3 Wastewater Treatment and 1,4-Dioxane Removal ...... 406
8.6.4 Communicating with Water Utilities and the
Public about 1,4-Dioxane in Drinking Water
Wells ............................................. 406
8.6.5 Institutional Measures to Prevent Future
Industrial Discharges Adverse to Recycling
Wastewater ........................................ 408
8.7 Air Force Plant 44, Tucson, Arizona ...................... 408
8.7.1 Background ........................................ 408
8.7.2 Geologic and Hydrogeologie Setting ................ 409
8.7.3 Chlorinated Solvent Use, Release Mechanisms, and
Discovery ......................................... 410
8.7.4 Community Involvement ............................. 411
8.7.5 Remedial Actions .................................. 412
8.7.6 1,4-Dioxane Discovery and Regulation .............. 413
8.7.7 Advanced Oxidation Treatment System Upgrade ....... 414
8.7.8 Cost Analysis ..................................... 416
8.7.9 Future Plans ...................................... 416
Acknowledgments ............................................... 417
Bibliography .................................................. 417
Chapter 9 Forensic Applications for 1,4-Dioxane and Solvent
Stabilizers ........................................ 421
9.1 Leveraging 1,4-Dioxane Data for Plume Analysis and
Source Apportionment ..................................... 422
9.1.1 Estimating the Mass of the Release ................ 422
9.1.2 Impurities ........................................ 426
9.2 Ratio Analysis ........................................... 436
9.2.1 Ratio Analysis of Methyl Chloroform Breakdown
Using 1,4-Dioxane ................................. 437
9.2.2 Using Ratios to Approximate the Date of
a Release ......................................... 438
9.2.3 Modeling 1,4-Dioxane Migration to Approximate
the Date of a Release ............................. 441
9.2.4 Compound-Specific Isotope Analysis ................ 442
9.2.5 Compound-Specific Isotope Analysis of 1,4-
Dioxane Biodegradation ............................ 444
9.3 Solvent Stabilizers as Age Markers ....................... 447
9.4 Solvent Stabilizers as Markers of Solvent Applications ... 447
9.4.1 PCE as a Dielectric Fluid ......................... 449
Bibliography .................................................. 452
Chapter 10 Regulatory Policy Implications of 1,4-Dioxane ...... 455
10.1 Applying the Precautionary Principle to Regulation of
1,4-Dioxane and Emerging Contaminants in Drinking
Water .................................................... 456
10.1.1 Emerging and Unregulated Contaminants ............. 460
10.2 1,4-Dioxane and Drinking Water Policy .................... 461
10.2.1 1,4-Dioxane Detections and Drinking Water
Testing Program Policy ............................ 461
10.2.2 USEPA's Contaminant Candidate List Includes
1,4-Dioxane ....................................... 462
10.2.3 Integrating Awareness of Groundwater Cleanups to
Prioritize 1,4-Dioxane Monitoring in Water
Supply Well Sampling Programs ..................... 462
10.2.4 Predicting Water Supply Well Contamination ........ 463
10.2.5 Moving Beyond Checklist Compliance ................ 465
10.3 Updating the Toxicological Basis for 1,4-Dioxane
Regulation ............................................... 467
10.3.1 Addressing Synergistic Effects of Multiple
Contaminants ...................................... 468
10.3.2 The Promise of Cell Lines to Accelerate and
Improve Toxicology Assays ......................... 469
10.3.3 Applying Computational Toxicology to
Physiologically Based Pharmacokinetic Modeling .... 470
10.4 Regulatory Policy on 1,4-Dioxane Remediation at Cleanup
Sites .................................................... 472
10.4.1 Monitored Natural Attenuation and 1,4-Dioxane ..... 472
10.4.2 1,4-Dioxane and National Pollution Discharge
Elimination System Effluent Limitations ........... 473
10.4.3 Lessons Learned from 1,4-Dioxane Case Studies ..... 474
10.4.4 1,4-Dioxane Treatment Technology Research Needs ... 475
10.5 Blindsided Again? ........................................ 476
10.6 The Promise of Green Chemistry ........................... 478
10.7 Should 1,4-Dioxane Be Banned? ............................ 481
10.8 Regulatory Policy Recommendations for Addressing 1,4-
Dioxane Releases ......................................... 482
Acknowledgments ............................................... 483
Bibliography .................................................. 483
Appendix 1: Synopses of Selected Patents from the Art of
Solvent Stabilization .................................... 487
Appendix 2: Fate and Transport Properties of Solvent-
Stabilizer Compounds ..................................... 491
Appendix 3: Compilation of Instrumental Parameters in
Literature Studies of 1,4-Dioxane Analyses of Various
Media .................................................... 497
Index ......................................................... 505
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