U.S. Environmental Protection Agency
Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009)
November 15, 1996
HAZARDOUS WASTE CHARACTERISTICS SCOPING STUDY
                        TABLE OF CONTENTS
                                                      Page
EXECUTIVE SUMMARY. . . . . . . . . . . . . . . . . . . ES-1
CHAPTER 1.     INTRODUCTION. . . . . . . . . . . . . . 1-1
          1.1  Purpose and Requirements of the Hazardous
               Waste Characteristics Scoping Study . . 1-1
          1.2  Regulatory Background . . . . . . . . . 1-2
          1.3  Approach for Studying Potential Gaps in
               the Hazardous Waste Characteristics . . 1-4
               Step 1:   Characterize Releases from
                         Non-Hazardous Industrial Waste
                         Management. . . . . . . . . . 1-4
               Step 2:   Categorize Risks Associated
                         with Non-Hazardous Industrial Waste
                         Management. . . . . . . . . . 1-4
               Step 3:   Review the Existing
                         Characteristics . . . . . . . 1-4
               Step 4:   Identify Gaps Associated with
                         Non-TC Chemicals. . . . . . . 1-6
               Step 5:   Identify Potential Gaps
                         Associated with Certain
                         Natural Resource Damages and
                         Large-Scale Environmental
                         Problems. . . . . . . . . . . 1-6
               Step 6:   Review State Expansions of
                         TC and State Listings . . . . 1-7
               Step 7:   Evaluate the Industries and
                         Waste Management Practices
                         Associated with Potential
                         Gaps. . . . . . . . . . . . . 1-7
               Step 8:   Assess Regulatory Programs'
                         Coverage of Potential Gaps. . 1-8
               Step 9:   Present Integrated Evaluation
                         of Nature and Extent of
                         Potential Gaps. . . . . . . . 1-8
          1.4  Report Outline. . . . . . . . . . . . . 1-8
CHAPTER 2.     RELEASES FROM NON-HAZARDOUS INDUSTRIAL
               WASTE MANAGEMENT UNITS. . . . . . . . . 2-1
          2.1  Methodology . . . . . . . . . . . . . . 2-1
               2.1.1     Criteria For Selecting
                         Releases. . . . . . . . . . . 2-1
               2.1.2     Approach For Identifying
                         Releases. . . . . . . . . . . 2-3
                    2.1.2.1  State Industrial D
                             Programs. . . . . . . . . 2-3
                    2.1.2.2  State Superfund Programs. 2-5
                    2.1.2.3  Federal Superfund Program 2-6
                    2.1.2.4  Construction and
                             Demolition (C&D) Landfill
                             Report. . . . . . . . . . 2-6
               2.1.3     Release Profile Preparation . 2-7
          2.2  Results . . . . . . . . . . . . . . . . 2-8
               2.2.1     Number of Cases By State. . . 2-8
               2.2.2     Number of Cases By Industry . 2-10
               2.2.3     Number of Cases By Type of
                         Waste Management Unit . . . . 2-11
               2.2.4     Type of Media Affected. . . . 2-12
               2.2.5     Types of Contaminants
                         Released. . . . . . . . . . . 2-13
          2.3  Major Limitations . . . . . . . . . . . 2-17
CHAPTER 3.     POTENTIAL GAPS ASSOCIATED WITH HAZARDOUS
               WASTE CHARACTERISTICS DEFINITIONS . . . 3-1
          3.1  Types of Risks Addressed by RCRA
               Hazardous Waste Characteristics . . . . 3-1
               3.1.1     Statutory and Regulatory
                         Framework . . . . . . . . . . 3-1
               3.1.2     Risks Associated with
                         Physical Hazards. . . . . . . 3-3
               3.1.3     Acute Toxic Hazards to Humans 3-4
               3.1.4     Chronic Toxicity Risks to
                         Humans. . . . . . . . . . . . 3-4
               3.1.5     Risks to Non-Human Receptors. 3-5
               3.1.6     Other Risks Associated with
                         Non-Hazardous Industrial Waste
                         Management. . . . . . . . . . 3-6
          3.2  Ignitability Characteristic . . . . . . 3-8
               3.2.1     Definition of Ignitability. . 3-8
               3.2.2     Potential Gaps Related to
                         Definition of Ignitability. . 3-9
               3.2.3  Potential Gaps Related to
                      Ignitability Test Methods. . . . 3-12
          3.3  Corrosivity . . . . . . . . . . . . . . 3-12
               3.3.1     Definition of Corrosivity . . 3-12
               3.3.2     Potential Gaps Related to
                         Definition of Corrosivity . . 3-13
               3.3.3     Potential Gaps Related to
                         Corrosivity Test Methods. . . 3-16
          3.4  Reactivity. . . . . . . . . . . . . . . 3-16
               3.4.1     Definition of Reactivity. . . 3-16
               3.4.2     Potential Gaps Related to
                         Definition of Reactivity. . . 3-17
               3.4.3     Potential Gaps Related to
                         Reactivity Test Methods . . . 3-19
          3.5  Potential Gaps Associated with the
               Toxicity Characteristic . . . . . . . . 3-19
               3.5.1     Definition of Toxicity
                         Characteristic. . . . . . . . 3-19
               3.5.2     Changes in Groundwater Pathway
                         Analysis. . . . . . . . . . . 3-21
               3.5.3     Potential Inhalation Pathway
                         Risks Associated with TC
                         Analytes. . . . . . . . . . . 3-27
               3.5.4     Potential Risks from Surface
                         Water Exposures. . . . . . . . 3-33
               3.5.5     Potential Indirect Pathway
                         Risks from TC Analytes . . . . 3-35
               3.5.6     Potential for Acute Adverse
                         Effects of Exposures to TC
                         Analytes. . . . . . . . . . . 3-38
               3.5.7     Potential Risks to Ecological
                         Receptors from TC Analytes. . 3-38
          3.6  Potential Gaps Associated with TCLP . . 3-39
               3.6.1     TCLP Background . . . . . . . 3-39
               3.6.2     Limitations of the TCLP . . . 3-42
CHAPTER 4.     POTENTIAL GAPS ASSOCIATED WITH NON-TC
               CHEMICALS . . . . . . . . . . . . . . . 4-1
          4.1  Overview of Methodology . . . . . . . . 4-1
               Step 1:  Identify and Classify Known
                        Non-Hazardous Industrial Waste
                        Constituents . . . . . . . . . 4-1
               Step 2:  Identify and Screen Possible
                        Non-Hazardous Industrial Waste
                        Constituents . . . . . . . . . 4-1
               Step 3:  Apply Hazard-Based Screening
                        Criteria . . . . . . . . . . . 4-3
               Step 4:  Review Relevant Multipathway
                        Risk Modeling Results. . . . . 4-3
               Step 5:  Identify Potential Acute
                        Hazards. . . . . . . . . . . . 4-3
               Step 6:  Summarize Findings . . . . . . 4-3
          4.2  Identify and Classify Known Constituents
               of Non-Hazardous Industrial Wastes. . . 4-3
          4.3  Identify Possible Non-Hazardous
               Industrial Waste Constituents of
               Potential Concern . . . . . . . . . . . 4-7
               4.3.1     Approach to Identifying
                         Potentially Hazardous
                         Chemicals . . . . . . . . . . 4-7
               4.3.2     Screening Approach. . . . . . 4-9
               4.3.3     Toxicity, Fate, and Transport
                         Screening for Possible
                         Non-Hazardous Industrial
                         Waste Constituents. . . . . . 4-12
               4.3.4     Release Volume Screening of
                         Possible Non-Hazardous
                         Industrial Waste
                         Constituents. . . . . . . . . 4-15
               4.3.5     Summary of Possible
                         Non-Hazardous Industrial Waste
                         Constituents. . . . . . . . . 4-20
          4.4  Combine and Screen Known and Possible
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-20
               4.4.1     Combine the Lists . . . . . . 4-20
               4.4.2     Screen Combined List Against
                         Single Criteria . . . . . . . 4-25
               4.4.3     Screen Combined List Against
                         Multiple Parameters . . . . . 4-33
          4.5  Driving Risk Pathways for the Known and
               Possible Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-34
          4.6  Potential Acute Hazards Associated With
               Known and Possible Non-Hazardous
               Industrial Waste Constituents . . . . . 4-35
          4.7  Identify Individual Chemicals and
               Classes of Chemicals Constituting
               Potential Gaps. . . . . . . . . . . . . 4-40
CHAPTER 5.     POTENTIAL GAPS ASSOCIATED WITH NATURAL
               RESOURCE DAMAGES AND LARGE-SCALE
               ENVIRONMENTAL PROBLEMS. . . . . . . . . 5-1
          5.1  Damage to Groundwater Resources . . . . 5-1
          5.2  Damage to Local Air Quality from Odors. 5-2
          5.3  Large-Scale Environmental Problems. . . 5-4
               5.3.1     Air Deposition to the Great
                         Waters. . . . . . . . . . . . 5-4
               5.3.2     Airborne Particulates . . . . 5-6
               5.3.3     Global Climate Change . . . . 5-7
               5.3.4     Potential Damages from
                         Endocrine Disruptors. . . . . 5-9
               5.3.5     Red Tides . . . . . . . . . . 5-13
               5.3.6     Stratospheric Ozone Depletion 5-14
               5.3.7     Tropospheric Ozone and
                         Photochemical Air Pollution . 5-15
               5.3.8     Water Pollution . . . . . . . 5-15
CHAPTER 6.     STATE EXPANSIONS OF THE TOXICITY
               CHARACTERISTIC AND LISTINGS . . . . . . 6-1
          6.1  State Expanded Toxicity Characteristics 6-1
          6.2  State Only Listings . . . . . . . . . . 6-2
          6.3  State Restrictions on Exemptions. . . . 6-5
          6.4  Summary . . . . . . . . . . . . . . . . 6-6
CHAPTER 7.     SUMMARY OF POTENTIAL GAPS . . . . . . . 7-1
          7.1  Organization of the Analysis of
               Potential Gaps. . . . . . . . . . . . . 7-1
          7.2  Summary of Potential Gaps . . . . . . . 7-2
CHAPTER 8.     POTENTIAL GAPS AS FUNCTION OF INDUSTRY
               AND WASTE MANAGEMENT METHODS. . . . . . 8-1
          8.1  Data Sources and Major Limitations. . . 8-1
          8.2  Potential Gaps as a Function of
               Industry/Waste Source . . . . . . . . . 8-3
               8.2.1     Non-Hazardous Industrial
                         Waste Generation by Industry. 8-3
               8.2.2     Industries Responsible for
                         Documented Non-Hazardous
                         Industrial Waste Releases . . 8-5
               8.2.3     Occurrence of High-Hazard
                         Industrial Waste Constituents
                         by Industry . . . . . . . . . 8-8
               8.2.4     Industries Reporting Releases
                         of TC Analytes or Known or
                         Possible Non-Hazardous
                         Industrial Waste Constituents 8-18
          8.3  Potential Gaps as a Function of
               Management Practices. . . . . . . . . . 8-21
               8.3.1     Waste Management Practices by
                         Waste Type and Industry . . . 8-21
               8.3.2     Management Practices Seen in
                         the Release Descriptions. . . 8-24
               8.3.3     Potential Hazards Associated
                         with Use Constituting
                         Disposal. . . . . . . . . . . 8-29
               8.3.4     Potential Hazards Associated
                         with Other Management
                         Practices . . . . . . . . . . 8-31
CHAPTER 9.     POTENTIAL FOR GAPS TO BE ADDRESSED BY
               EXISTING REGULATIONS. . . . . . . . . . 9-1
          9.1  RCRA Programs . . . . . . . . . . . . . 9-1
               9.1.1  Hazardous Waste Programs . . . . 9-1
               9.1.2  Subtitle D . . . . . . . . . . . 9-3
          9.2  Medium-Specific Regulations . . . . . . 9-3
               9.2.1  Clean Water Act. . . . . . . . . 9-4
               9.2.2  Safe Drinking Water Act. . . . . 9-7
               9.2.3  Clean Air Act Amendments . . . . 9-10
          9.3  Federal Insecticide, Fungicide, and
               Rodenticide Act . . . . . . . . . . . . 9-13
          9.4  Toxic Substance Control Act . . . . . . 9-15
          9.5  Pollution Prevention. . . . . . . . . . 9-15
          9.6  Occupational Safety and Health Act. . . 9-16
          9.7  Hazardous Materials Transportation Act. 9-16
          9.8  Summary . . . . . . . . . . . . . . . . 9-19
CHAPTER 10.    SUMMARY EVALUATION OF NATURE AND EXTENT
               OF POTENTIAL GAPS . . . . . . . . . . . 10-1
          10.1 Overview of the Evaluation of Potential
               Gaps. . . . . . . . . . . . . . . . . . 10-1
               10.1.1    Objectives of the Gaps
                         Analysis. . . . . . . . . . . 10-1
               10.1.2    Criteria Used for Evaluating
                         Gaps. . . . . . . . . . . . . 10-1
          10.2 Findings of the Evaluation. . . . . . . 10-3
               10.2.1    Potential Gaps Associated
                         with the ICR Characteristics. 10-3
               10.2.2    Potential Gaps Associated
                         with TC Analytes. . . . . . . 10-8
               10.2.3    Potential Gaps Associated
                         with Non-TC Waste
                         Constituents. . . . . . . . . 10-14
               10.2.4    Potential Gaps Associated
                         With Resource Damage and
                         Large-Scale Environmental
                         Problems. . . . . . . . . . . 10-22
               10.2.5  Gaps Associated with State TC
                       Expansions and Listings . . . . 10-25
               10.2.6  Major Data Gaps and
                       Uncertainties . . . . . . . . . 10-26
          10.3 Framework for Determining an Appropriate
               Course of Action. . . . . . . . . . . . 10-27
               10.3.1    Step 1:  Identify Critical
                                  Research Needs and
                                  Next Steps Necessary
                                  to Analyze Key Issues
                                  and Fill Major Data
                                  Deficiencies. . . .  10-27
               10.3.2    Step 2:  Identify and Evalu-
                                  ate Options to
                                  Address Any Clearly
                                  Identified Gaps. . . 10-27
                         LIST OF EXHIBITS
                                                     Page
Exhibit 1-1    Scoping Study Approach. . . . . . . . . 1-5
Exhibit 2-1    Number of Release Descriptions By State 2-9
Exhibit 2-2    Number of Management Units & Volume of
               Waste Managed On-Site, by State (1985). 2-9
Exhibit 2-3    Number of Case Studies by Industry
               (SIC) . . . . . . . . . . . . . . . . . 2-10
Exhibit 2-4    Number of Case Studies By Waste
               Management Unit . . . . . . . . . . . . 2-12
Exhibit 2-5    TC Contaminants Detected in Case
               Studies . . . . . . . . . . . . . . . . 2-14
Exhibit 2-6    Contaminants with SMCLs Detected in
               Case Studies. . . . . . . . . . . . . . 2-15
Exhibit 2-7    Other Contaminants Detected in At Least
               Three Case Studies. . . . . . . . . . . 2-16
Exhibit 2-8    Most Common Constituents By Industry. . 2-18
Exhibit 3-1    Risks Potentially Associated with
               Non-Hazardous Industrial Waste
               Management. . . . . . . . . . . . . . . 3-7
Exhibit 3-2    Materials Formerly Classified by DOT
               as Combustible Liquids (which generally
               are not RCRA ignitable) . . . . . . . . 3-11
Exhibit 3-3    Other Definitions of Reactivity . . . . 3-18
Exhibit 3-4    TC Constituents and Regulatory Levels
               (mg/l). . . . . . . . . . . . . . . . . 3-20
Exhibit 3-5    Comparison of TC Regulatory Concentra-
               tions and HWIR-Waste Proposed Exit/
               Leech Levels. . . . . . . . . . . . . . 3-25
Exhibit 3-6    Summary of Inhalation Pathway Screening
               Methods, Input Data, and Models Used
               for Bounding Risk Analysis. . . . . . . 3-29
Exhibit 3-7    Emission Fraction for Air Releases of
               Volatile TC Analytes. . . . . . . . . . 3-30
Exhibit 3-8    Inhalation Pathway Risks for TC
               Analytes and Their Dependence on Fate
               and Transport Properties. . . . . . . . 3-32
Exhibit 3-9    Major Fate and Transport Parameters for
               TC Analytes . . . . . . . . . . . . . . 3-36
Exhibit 3-10   Ratios of TC Leachate Regulatory Levels
               to Ambient Water Quality Criteria for
               Aquatic Life. . . . . . . . . . . . . . 3-40
Exhibit 4-1    Flow Chart of Procedures Used to
               Identify Non-TC Chemicals Posing
               Potential Gaps in the TC
               Characteristics . . . . . . . . . . . . 4-2
Exhibit 4-2    Known Non-Hazardous Industrial Waste
               Constituents Found in Case Studies,
               ISDB, Listings Documents, and Effluent
               Guidelines by Chemical Class. . . . . . 4-6
Exhibit 4-3    Lists Used to Identify Possible
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-8
Exhibit 4-4    Criteria Considered for Screening
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-10
Exhibit 4-5    Toxicity Screening Results for Possible
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-13
Exhibit 4-6    Persistence and Bioconcentration/
               Bioaccumulation Screening Results for
               Possible Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-16
Exhibit 4-7    Screening of High-Toxicity, Persistent,
               Bioaccumulative/Bioconcentrating
               Possible Non-Hazardous Industrial Waste
               Constituents Against TRI Release
               Volumes . . . . . . . . . . . . . . . . 4-17
Exhibit 4-8    Possible Non-Hazardous Industrial Waste
               Constituents by Chemical Class. . . . . 4-21
Exhibit 4-9    Screening of Known Non-Hazardous
               Industrial Waste Constituents Against
               TRI Release Volumes . . . . . . . . . . 4-22
Exhibit 4-10   Toxicity Summary of Known and Possible
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-26
Exhibit 4-11   Potential Endocrine Disruptors. . . . . 4-27
Exhibit 4-12   TRI Releases and Non-Confidential TSCA
               Production Volume Data for the Known
               and Possible Non-Hazardous Industrial
               Waste Constituents. . . . . . . . . . . 4-28
Exhibit 4-13   Volatility, Persistence, and Bio-
               accumulation/Bioconcentration Summary
               Potential of Known and Possible
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-29
Exhibit 4-14   LNAPL/DNAPL Formation Potential of
               Known and Possible Non-Hazardous
               Industrial Waste Constituents . . . . . 4-32
Exhibit 4-15   Multiple Screening Criteria Applied to
               Known and Possible Non-Hazardous
               Industrial Waste Constituents . . . . . 4-34
Exhibit 4-16   Lowest Proposed HWIR-Waste Exit Levels
               for Known and Possible Non-Hazardous
               Industrial Waste Constituents . . . . . 4-36
Exhibit 4-17   Potential Acute Hazards Associated with
               Known and Possible Non-Hazardous
               Industrial Waste Constituents . . . . . 4-39
Exhibit 4-18   Potential Gaps in the Hazardous Waste
               Characteristics Identified Based on the
               Hazardous Properties of Known and
               Possible Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 4-41
Exhibit 5-1    Constituents/Properties with SMCLs Found in
               Release Descriptions. . . . . . . . . . 5-2
Exhibit 5-2    Chemicals from Release Descriptions
               with Low Odor Thresholds. . . . . . . . 5-3
Exhibit 5-3    Initial List of Large-Scale
               Environmental Problems. . . . . . . . . 5-4
Exhibit 5-4    U.S. Sources of Air Pollutants of
               Concern for Great Waters. . . . . . . .  5-5
Exhibit 6-1    State Toxicity Characteristics:
               Additional Constituents and More
               Stringent Regulatory Levels . . . . . . 6-3
Exhibit 6-2    State Toxicity Criteria Applied to
               Whole Waste (Representative Sample) . . 6-4
Exhibit 7-1    Summary of Potential Gaps in the
               Hazardous Waste Characteristics . . . . 7-2
Exhibit 8-1    Estimated Generation of Non-Hazardous
               Industrial Waste by Major Industry
               Group . . . . . . . . . . . . . . . . . 8-4
Exhibit 8-2    Chemicals Exceeding Health-Based and
               Non-Health-Based Regulatory Levels
               in the Release Descriptions for
               Non-Hazardous Waste Management. . . . . 8-6
Exhibit 8-3    Numbers of Chemical Detections and
               Frequencies of Regulatory Exceedences
               in Release Descriptions . . . . . . . . 8-7
Exhibit 8-4    Most Frequently Occurring Constituents
               in the Release Descriptions . . . . . . 8-9
Exhibit 8-5    Occurrence of Waste Constituents by
               Industry Group. . . . . . . . . . . . . 8-11
Exhibit 8-6    Non-Hazardous Industrial Waste
               Constituents Reported Released by
               Industry. . . . . . . . . . . . . . . . 8-19
Exhibit 8-7    Volume of Non-Hazardous Industrial
               Waste Managed in Land-Based Facilities
               in 1985 . . . . . . . . . . . . . . . . 8-22
Exhibit 8-8    Active Non-Hazardous Industrial Waste
               Management Units in 1985 by Major
               Industry Group. . . . . . . . . . . . . 8-23
Exhibit 8-9    Non-Hazardous Industrial Waste
               Management by Industry and Waste Type
               from TSDR and ISDB. . . . . . . . . . . 8-25
Exhibit 8-10   Waste Management Unit Types in the
               Release Descriptions  . . . . . . . . . 8-30
Exhibit 9-1    TC Constituents with Effluent Limits
               Established under CWA . . . . . . . . . 9-5
Exhibit 9-2    CWA Effluent Limitations Relevant to
               Certain Known Non-Hazardous Industrial
               Waste Constituents. . . . . . . . . . . 9-6
Exhibit 9-3    CWA Coverage of Industries Represented
               in Release Descriptions . . . . . . . . 9-7
Exhibit 9-4    TC Constituents with SDWA MCL Levels. . 9-8
Exhibit 9-5    MCLs for Known Non-Hazardous Industrial
               Waste Constituents of Concern in
               Groundwater Pathways. . . . . . . . . . 9-9
Exhibit 9-6    TC Constituents Designated as HAPs
               under CAA . . . . . . . . . . . . . . . 9-11
Exhibit 9-7    CAA Hazardous Air Pollutants (HAPs)
               Specified for Potential Gap
               Constituents. . . . . . . . . . . . . . 9-12
Exhibit 9-8    CAA Coverage of Industries Represented
               in Release Descriptions . . . . . . . . 9-13
Exhibit 9-9    Status of Pesticides That are TC
               Analytes or Known Non-Hazardous
               Industrial Waste Constituents . . . . . 9-14
Exhibit 9-10   TC Constituents with Established OSHA
               PELs. . . . . . . . . . . . . . . . . . 9-17
Exhibit 9-11   OSHA PELs Specified for Known
               Non-Hazardous Industrial Waste
               Constituents. . . . . . . . . . . . . . 9-18
Exhibit 9-12   Potential Gaps and Potential Non-RCRA
               Regulatory Control. . . . . . . . . . . 9-19
Exhibit 10-1   Evaluation of Potential Gaps Associated
               With the Ignitability, Corrosivity, and
               Reactivity (ICR) Characteristics. . . . 10-4
Exhibit 10-2   Evaluation of Potential Gaps Associated
               with Toxicity Characteristic Analytes
               and TCLP. . . . . . . . . . . . . . . . 10-9
Exhibit 10-3   Evaluation of Potential Gaps Associated
               with Non-TC Chemicals . . . . . . . . . 10-15
Exhibit 10-4   Evaluation of Potential Gaps Associated
               With Certain Large-Scale Environmental
               Problems. . . . . . . . . . . . . . . . 10-24
HAZARDOUS WASTE CHARACTERISTICS SCOPING STUDY:
EXECUTIVE SUMMARY
U.S. Environmental Protection Agency
Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009)
November 15, 1996
EXECUTIVE SUMMARY
The U.S. Environmental Protection Agency (EPA), Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009) has investigated potential gaps in the current
hazardous waste characteristics promulgated under the
federal Resource Conservation and Recovery Act (RCRA). This
report, the Hazardous Waste Characteristics Scoping Study,
presents the findings of that investigation.
THE SCOPING STUDY:  AN EARLY STEP
This study is a first step for the Agency in fulfilling a
long-standing goal to review the adequacy and
appropriateness of the hazardous characteristics. The study
also fulfills an obligation in a consent decree with the
Environmental Defense Fund (EDF).
The study is by design a scoping study and, therefore, does
not conclusively identify particular chemical classes for
regulation, or fundamental flaws in the overall regulatory
framework requiring immediate regulatory action. However,
the study does identify several key areas that merit further
analysis due to the significant potential for improving
hazardous waste management practices and protection to
health and the environment. Thus, the scoping study provides
a catalogue of potential gaps in the hazardous waste
characteristics.
The Agency considers that this study is one very critical
component of a broader array of efforts underway to review
and improve the RCRA program, to ensure that regulation is
appropriate to the degree of risk posed by hazardous wastes
and waste management practices. Efforts involve both
regulatory and de-regulatory actions, as appropriate for
specific wastes and waste management practices.
STUDY PROCESS AND FINDINGS
Review of Current Characteristics
The review of the current characteristic regulations
evaluated the protectiveness of the characteristics against
the risks they were intended to address and also risks they
were not specifically intended to address. For example, EPA
evaluated risks that are now addressed by the Toxicity
Characteristic (TC), e.g., direct ingestion of groundwater,
by considering new groundwater modeling techniques that have
been in use since the promulgation of the current TC levels,
as well as any changes to the toxicity values on which the
original levels were based. In addition, EPA evaluated risks
from other exposure pathways and to ecological receptors,
which are both risks not intended to be protected by the
original TC.
The review of the current TC regulatory levels suggests
that:  (1) further analysis of the current TC regulatory
levels should be conducted using new groundwater modeling
techniques, as well as considering changes to toxicity
values for specific constituents; and (2) non-groundwater
pathways and ecological receptors--not currently addressed
by TC provisions--may be of potential concern. The study
included some screening analyses of potential air releases
from surface impoundments and land application units. The
Agency found that inhalation risk levels for a significant
number of current TC constituents at the fenceline (under
certain exposure conditions) exceeded the allowable risk
levels upon which the TC is based.
Waste piles and land application units may be of special
concern for ecological receptors due to surface runoff.
Thirteen TC constituents have regulatory levels that are
10,000 or more times higher than Ambient Water Quality
Criteria concentrations, with four of these being at least
100,000 times higher, suggesting that the level of
protectiveness of the TC may not be very high for ecological
receptors.
The study also identifies the need to examine a broader
array of leaching procedures, in addition to the Toxicity
Characteristic Leaching Procedure (TCLP), to better predict
environmental releases from various waste types and waste
management conditions. Notable examples are the inability of
the TCLP to predict significant releases under highly
alkaline conditions or to media other than groundwater, or
to serve as a leaching procedure for oily wastes.
The most obvious potential gap identified for the
ignitability and reactivity characteristics is the reference
to outdated DOT regulations. Other potential gaps identified
for these characteristics include the exclusion of
combustible liquids and lack of specific test methods for
non-liquids for ignitability; exclusion of corrosive solids,
not addressing corrosion of non-steel materials and
solubilization of non-metals, and whether pH limits are
adequately protective for corrosivity; and, an overly-broad
definition and lack of specific test methods for reactivity.
Releases from Non-Hazardous Industrial Waste Facilities
The Agency identified actual releases of non-hazardous waste
constituents as one means of finding potential problem
constituents and management activities. EPA reviewed data on
non-hazardous industrial waste management activities that
was readily available from state monitoring and compliance
files. The Agency focused on wastes that are not currently
regulated as hazardous (by virtue of being listed or
exhibiting a characteristic) to identify releases
potentially causing human health or environmental damages.
The Agency considered three major factors in judging whether
a release was an appropriate case study for this evaluation.
A release had to meet all three of the following criteria to
be included: (1) The source of contamination had to be a
waste management unit or other intended final disposal area
that received only non-hazardous industrial waste; (2)  A
release from a waste management unit must have caused
contamination at levels of potential concern
(constituent-specific concentrations that exceed federal
standards or state guidelines or regulations); and, (3)
Documented evidence must be available to support the
exceedences referred to in (2).
EPA found 112 environmental release case studies in 12
states with readily available (and not necessarily
representative) data on non-hazardous waste management
units. The releases were found from facilities in 15
(2-digit) Standard Industry Classification (SIC) industries.
The top four categories were: SIC 49:  Electric, Gas, and
Sanitary Services (refuse-side only); SIC 26:  Paper &
Allied Products; SIC 28:  Chemical & Allied Products; and,
SIC 20:  Food & Kindred Products.
Over 90 percent of the releases were from landfills or
surface impoundments and nearly all (98 percent) involved
groundwater contamination. This is most likely because
groundwater monitoring is the most common method for
detecting releases from waste management units.
Many of the chemical constituents most commonly detected
above a regulatory level are already addressed in the
current TC,  even though the release occurred from
non-hazardous waste management. The 20 constituents most
commonly detected above a regulatory level are inorganics.
The constituents that exceeded state groundwater protection
standards or health-based federal drinking water standards
most frequently were  lead, chromium, cadmium, benzene,
arsenic and nitrates. All of these, with the exception of
nitrates, are current TC constituents. Organic constituents,
both TC and non-TC, were also identified in the case
studies, however, they were detected less frequently than
the inorganic toxicity characteristic constituents.
This collection of release descriptions is not statistically
representative of problem industries nor intended to
identify particular problem facilities. The Agency believes
that the case studies are indicative of the type of releases
associated with the management of non-hazardous wastes in
the types of facilities identified. The Agency also believes
that information on releases from  past waste management
practices is useful in demonstrating the potential for human
health or environmental damage.
Non-TC Chemical Constituents
In reviewing chemicals and chemical classes not currently
regulated by the TC, EPA found in excess of 100 constituents
that potentially occur in waste and may pose significant
risks. EPA reviewed 37 regulatory or advisory lists of
chemicals to identify possible constituents of non-hazardous
wastes. EPA also compiled a list of chemicals which are
"known" to be constituents of non-hazardous wastes because
they were identified in the environmental release case
studies or other Agency data sources on non-hazardous
industrial wastes. EPA screened these chemicals and narrowed
the list to possible constituents of non-hazardous waste
that, by virtue of their toxicity, fate and transport
properties, or exposure potential, could pose significant
risks to human health and/or the environment.
These chemicals were both inorganics and organics, and
include volatiles, non-volatile organics, PAHs and
pesticides. Because of the large number of constituents
identified as candidates and the limited time available for
the scoping study, no risk analyses were conducted. However,
it may be a reasonable next step to assess the potential
risks for a subset of these constituents.
Natural Resource Damages/Large-Scale Environmental Problems
The Agency examined the potential for broad environmental
impacts from non-hazardous waste management. These impacts
may include damages to natural resources which diminish the
value and usability of a resource without threatening human
health, as well as possible contributions to regional and
global environmental problems.
With respect to groundwater contamination, over 80 percent
of the facilities identified in the case studies discussed
earlier had releases exceeding secondary drinking water
standards (non-health based standards). These releases were
identified because exceedence of secondary standards may
reduce the useability and, therefore, the value of  the
groundwater. Iron, chloride, sulfate and manganese were
among the most  frequently detected constituents exceeding
secondary standards.
In reviewing air deposition of toxic constituents to great
waters, the Agency found a number of TC constituents, as
well as some other chemicals identified in the study.
However, it was not possible to assess the importance of
waste to air deposition of toxics to the great waters.
State-Only Hazardous Waste Regulations
Some states have adopted hazardous waste identification
rules that are broader or more stringent than federal RCRA
Subtitle C regulations. These expansions reflect state
judgements about gaps in the federal program. Data on
hazardous waste regulations from eight states, California,
Michigan, New Hampshire, Oregon, Rhode Island, Texas,
Washington, and New Jersey were considered. Several states
regulate additional constituents beyond the TC list ( 25 for
California, 9 for Michigan, and 1 for Washington).
California also applies a more aggressive leaching test, the
waste extraction test (WET) to wastes. California also has a
test for combinations of hazardous constituents, in which a
combined concentration of the listed constituents cannot
exceed 0.001 percent as a total in the waste. Four states
also apply acute toxicity values (LD50 or LC50) for human or
ecological toxicity to the whole waste.
NEXT STEPS
The potential gaps and areas of health and environmental
concern identified here will require further, more detailed
examination before regulatory action can be undertaken. For
example, the study highlights risks to ecological receptors
and possible inhalation risks to humans as potential gaps,
as well as further evaluation of the adequacy of the TCLP.
These topics were found to be potential gaps in more than
one area of the study and will likely be specific areas of
further investigation.
Following release of this report, the Agency will engage in
a variety of outreach activities in identifying appropriate
next steps. While the Agency considers this a final report,
comments from interested members of the public are solicited
and will be used to help identify and structure follow-on
activities. As noted above, revisions to the characteristics
program will likely, in the long run, involve both
regulatory and de-regulatory activities.
CHAPTER 1. INTRODUCTION
The U.S. Environmental Protection Agency (EPA), Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009) has investigated potential gaps in the current
hazardous waste characteristics promulgated under the
federal Resource Conservation and Recovery Act (RCRA). This
report, the Hazardous Waste Characteristics Scoping Study,
presents the findings of that investigation. Chapter 1
presents background information on the Scoping Study as
follows:
!    Section 1.1 describes the purpose and scope of the
Scoping Study;
!    Section 1.2 discusses relevant aspects of the RCRA
hazardous waste and non-hazardous waste programs;
!    Section 1.3 summarizes the methodology used to prepare
the Scoping Study; and
!    Section 1.4 outlines the remaining chapters and
appendices of the Study.
1.1  Purpose and Requirements of the Hazardous Waste
Characteristics Scoping Study
Agreement for Hazardous Waste Characteristics Scoping Study
The Administrator shall perform a study of potential gaps in
the coverage of the existing hazardous waste
characteristics. The purpose of the study is to investigate
if there are gaps in coverage, and the nature and extent of
the gaps identified. The potential gaps in coverage to be
addressed in the study [shall] incorporate both waste
management practices and possible impacts to human health
and the environment. With respect to waste management
practices, the study shall, at a minimum, address releases
from non-hazardous waste surface impoundments; waste piles;
land treatment units; landfills; and various forms of use
constituting disposal such as road application, dust
suppression or use in a product applied to the land. Human
health and environmental impacts to be addressed by the
study shall include, but not be limited to:  (a) impacts via
non-groundwater exposure pathways, both direct and indirect,
to human and ecological receptors; (b) impacts via the
groundwater pathway to ecological receptors; (c) the
potential for formation of non-aqueous phase liquids in
groundwater; and (d) impacts via the groundwater pathway to
human receptors caused by releases of toxic constituents not
included in the current toxicity characteristic, such as
EPA-classified carcinogens, priority pollutants identified
in the Clean Water Act, and solvents used for purposes other
than degreasing. The Administrator shall complete the study
by November 15, 1996, and shall provide the plaintiff with
two copies of the study immediately upon completion.
Environmental Defense Fund, Inc. v. Browner, Civ. No.
89-0598, order granting stipulated motion of EDF and EPA for
amendment of consent decree. May 17, 1996, pp. 18-19.
1
As stipulated under an amended consent decree with the
Environmental Defense Fund (EDF) (presented in the text box
below), the Agency has investigated potential gaps in the
coverage of the existing RCRA hazardous waste
characteristics. The purpose of this Study is to identify
potential gaps in coverage and to investigate the nature and
extent of such gaps. Based on the results of the Study, EPA
will seek input from interested parties and determine the
appropriate course of action to further address any
significant potential gaps identified in the Study.
1.2  Regulatory Background
This report focuses on wastes that are not currently
regulated as hazardous (by virtue of being listed or
exhibiting a characteristic). Industrial wastes are
classified either as "hazardous waste" and managed under
Subtitle C of the Resource Conservation and Recovery Act
(RCRA) or as "non-hazardous waste" and managed under
Subtitle D of RCRA, primarily under state programs. In the
context of this report, the term "non-hazardous industrial
waste" broadly refers to waste that is neither municipal
solid waste, special waste, nor considered a hazardous waste
under Subtitle C of RCRA. A brief description of the
Agency's hazardous and non-hazardous waste classification
systems is provided below.
Subtitle C of RCRA, as amended, establishes a federal
program for the comprehensive regulation of hazardous waste.
Section 1004(7) of RCRA defines hazardous waste as
"a solid waste, or a combination of solid wastes, which
because of its quantity, concentration, or physical,
chemical, or infectious characteristics may:  (a) cause, or
significantly contribute to an increase in mortality or an
increase in serious irreversible, or incapacitating
reversible, illness; or (b) pose a substantial present or
potential hazard to human health or the environment when
improperly treated, stored, transported, disposed of, or
otherwise managed."
Under RCRA Section 3001, EPA is charged with defining which
solid wastes are hazardous by identifying the
characteristics of hazardous waste and listing particular
hazardous wastes.
Current hazardous waste characteristics are ignitability,
corrosivity, reactivity, and toxicity. The Agency's
definitions of ignitability and reactivity have not changed
materially since their adoption in 1980.1  The Agency's
definition for corrosivity was last revised in 1993.2  The
Agency's current definition of toxicity was promulgated in
1990,3 replacing the Extraction Procedure (EP) leach test
with the Toxicity Characteristic Leaching Procedure (TCLP)
and adding 25 organic chemicals to the list of toxic
constituents of concern and establishing their regulatory
levels. The Agency's definition of toxicity was last revised
in 1993;4 however, this revision did not alter the framework
for defining this characteristic.
A solid waste is classified as listed hazardous waste if it
is named on one of the following four lists developed by
EPA:
!    Nonspecific source or F wastes (40 CFR 261.31). These
are generic wastes, commonly produced by manufacturing and
industrial processes. Examples include spent halogenated
solvents used in degreasing and wastewater treatment sludge
from electroplating processes as well as dioxin wastes, most
of which are "acutely hazardous" wastes due to the danger
they present to human health or the environment.
!    Specific source or K wastes (40 CFR 261.32). This list
consists of wastes from specifically identified industries
such as wood preserving, petroleum refining, and organic
chemical manufacturing. These wastes typically include
sludges, still bottoms, wastewaters, spent catalysts, and
residues.
!    Discarded commercial chemical products or P and U
wastes (40 CFR 261.33(e) and (f)). The third and fourth
lists consist of specific commercial chemical products and
manufacturing chemical intermediates. They include chemicals
such as chloroform and creosote, acids such as sulfuric acid
and hydrochloric acid, and pesticides such as DDT and
kepone.
Disposal of non-hazardous solid waste is regulated under
Subtitle D of RCRA. Subtitle D wastes include municipal
solid waste, special waste, and industrial waste.
!    Municipal solid waste includes household and commercial
solid waste. Household waste is defined as any solid waste
(including garbage, trash, and sanitary waste in septic
tanks) derived from households (including single and
multiple residences, hotels and motels, bunkhouses, ranger
stations, crew quarters, campgrounds, picnic grounds, and
day-use recreation areas) (40 CFR 258.2). Commercial waste
refers to all types of solid waste generated by stores,
offices, restaurants, warehouses, and other
non-manufacturing activities, excluding residential and
industrial wastes (40 CFR 258.2).
!    Special waste, as used in this document, refers to oil
and gas exploration and production waste, fossil fuel
combustion wastes, cement kiln dust, and solid waste from
the extraction, beneficiation, and processing of ores and
minerals (40 CFR 261.4).
!    Non-hazardous industrial waste refers to solid waste
generated by manufacturing or industrial processes that is
not a hazardous waste regulated under Subtitle C of RCRA or
a special waste (40 CFR 258.2).
Under Subtitle D, the management of non-hazardous industrial
waste in land-based units must comply with 40 CFR Part 257,
which establishes minimum federal standards for the
management and siting of land-based units. Individual states
are responsible for implementing 40 CFR Part 257 under their
own authority. They have adopted statutory and regulatory
frameworks for management of non-hazardous industrial
wastes. These requirements vary widely from one state to
another in terms of their design and operating requirements,
monitoring requirements, and other management requirements
such as recordkeeping, closure, post-closure care, and
financial responsibility. Even within a given state, the
non-hazardous industrial waste requirements may vary from
facility to facility depending on the characteristics of the
wastes managed and the environmental setting of the waste
management unit. The Agency is currently developing
"voluntary guidelines" for non-hazardous industrial waste
management to better ensure that this waste is managed in a
manner that is protective of human health and the
environment.
1.3  Approach for Studying Potential Gaps in the Hazardous
Waste Characteristics
As shown in Exhibit 1-1, the general approach EPA used to
perform the Scoping Study has nine steps. Each of these
steps is discussed below.
Step 1:  Characterize Releases from Non-Hazardous Industrial
Waste Management
The Agency conducted detailed investigations to identify
specific instances of environmental contamination resulting
from the management of non-hazardous industrial wastes.
These case studies provide real-world information on
releases of these wastes into the environment, the chemicals
released and their concentrations, and the waste management
practices and industries involved. The preliminary findings
of such research were presented in a draft report entitled
"Hazardous Waste Characteristics Scoping Study:
Environmental Release Descriptions" (September 24, 1996).
EPA held a public meeting on October 10, 1996 to explain and
obtain comments on the draft report. EPA has considered and,
where appropriate, incorporated these comments in preparing
this Scoping Study. Chapter 2 summarizes these
investigations and Appendix A presents the individual
environmental release descriptions.
Step 2:  Categorize Risks Associated with Non-Hazardous
Industrial Waste Management
This step identifies categories of risks to human health and
the environment that may result from non-hazardous
industrial waste management. The underlying premise of this
step is that a gap in the hazardous waste characteristics is
any significant risk to human health or the environment
associated with non-hazardous industrial waste management
that could be, but is not, addressed by the current
characteristics. Thus, this assessment deals with both:
!    Hazards that the current hazardous waste
characteristics were intended to address, namely physical
hazards such as fire and explosion and toxic groundwater
contamination near waste management facilities; and
!    Hazards that the characteristics were not intended to
address, such as non-groundwater pathway exposures to
toxins, damages to ecological receptors, and natural
resource damages.
EPA identified risks by types of receptors, types of toxic
effects and physical hazards, exposure pathways, and time
and spatial scales, as described in Section 3.1. The search
for potential risks used broad definitions of risk and
adverse effects and addressed all aspects of non-hazardous
industrial waste management, without any prejudgment as to
the likelihood that a risk was significant, whether it could
be best addressed by the characteristics, or whether it was
already addressed by other regulations. The results of this
risk classification step were used in identifying and
evaluating potential gaps, as described below.
Step 3:  Review the Existing Characteristics
The identification of potential gaps continues with a review
of the existing definitions of the characteristics. This
step is next for two reasons. First, limitations in the
characteristics' effectiveness in reducing the risks they
were intended to address may constitute important potential
gaps. When the characteristics were promulgated, the Agency
identified physical hazards and acute toxic hazards during
transport and disposal activities and chronic exposure to
groundwater contaminated with waste
Insert Exhibit 1-1  Scoping Study Approach
constituents as being among the most important waste
management risks. Reducing these risks remains an important
goal of the characteristics. Second, this analysis lays the
groundwork for evaluating other potential gaps.
Step 3 begins by examining the definitions and test methods
of the ignitability, corrosivity, and reactivity (ICR)
characteristics, which are essentially unchanged since they
were promulgated in 1980. EPA reviewed the assumptions and
approaches used to develop these characteristics and
compared the characteristics to approaches taken to
controlling similar hazards under other federal and state
regulatory schemes. Step 3 also examines the definition of
the toxicity characteristic (TC), which was designed to
protect against human health risks from exposure to
hazardous waste constituents released to groundwater. EPA
reviewed new information on the toxicity, fate, and
transport of the TC constituents and improvements in
groundwater modeling since the TC was revised in 1990. The
Agency also examined the potential risks from TC
constituents through inhalation, surface water, and indirect
pathways and to ecological receptors. Chapter 3 describes
these analyses.
Step 4:  Identify Gaps Associated with Non-TC Chemicals
Potential gaps in the hazardous characteristics from non-TC
chemicals are identified by, first, identifying two groups
of constituents:
!    "Known" non-hazardous industrial waste constituents:
constituents "known" to be present in non-hazardous
industrial wastes, based on the data gathered in the
environmental release descriptions in Step 2, EPA's 1987
Telephone Screening Survey of non-hazardous industrial waste
management facilities, EPA effluent guideline development
documents, and recent hazardous waste listing
determinations.
!    "Possible" non-hazardous industrial waste constituents:
constituents on various regulatory or advisory lists, which
were screened for their toxicity, fate, and transport
properties and for a proxy of their occurrence in
non-hazardous industrial waste, using available
environmental release data from the 1994 Toxics Release
Inventory.
Then, these two lists of constituents are evaluated and
compared and chemicals are classified by physical
properties, chemical composition, use, and origin. Finally,
potential gaps were identified by applying multiple
hazard-based screening criteria to specific chemicals and
chemical classes. Chapter 4 describes these analyses.
     Step 5:  Identify Potential Gaps Associated with
Certain Natural Resource Damages and Large-Scale
Environmental Problems
As discussed above, steps 3 and 4 respectively examine
potential gaps inherent in the current hazardous waste
characteristics and associated with adverse human health or
localized ecological effects from constituents not addressed
by the toxicity characteristic. Step 5 addresses a third set
of risks associated with non-hazardous industrial waste
management:  damages to natural resources that may not have
direct human health or ecological effects, and large-scale
environmental problems. The specific risks addressed are:
C    Pollution of groundwater by constituents that diminish
the value and usability of the resource without threatening
human health;
C    Air pollution through odors that harm the quality of
life but may not have severe health effects; and
C    Large-scale environmental problems, including air
deposition to the Great Waters, damages from endocrine
disruptors and airborne particulates, global climate change,
red tides, stratospheric ozone depletion, tropospheric ozone
and photochemical air pollution and water pollution.
Chapter 5 presents these analyses.
Step 6:  Review State Expansions of TC and State Listings
Several states have expanded their hazardous waste
management programs to regulate as hazardous certain wastes
or waste constituents that are not hazardous under the
federal program. Step 6 examines how states have expanded
their toxicity characteristics and have listed as hazardous
certain wastes that are not listed under the federal
program. (Step 3 examines how states have regulated
additional wastes by expanding their ICR characteristics.)
These expansions beyond the federal hazardous waste
identification rules reflect state judgments about gaps in
the federal hazardous waste program and thereby constitute
potential gaps that may merit further investigation. Chapter
6 presents this analysis. (Chapter 7 summarizes the
potential gaps identified in Chapters 3 through 6.)
Step 7:  Evaluate the Industries and Waste Management
Practices Associated with Potential Gaps
The evaluation of potential gaps asks two basic questions:
(1) What do the qualitative and quantitative indicators of
risk show about the potential gaps? and (2) To what extent
are the risks associated with the potential gaps addressed
by other regulations?  Steps 7, 8, and 9 address these
questions. Step 7 addresses aspects of the first question.
Specifically, it assesses the following:
!    The amount of non-hazardous industrial wastes generated
by various industries;
!    The frequency with which various chemicals were
detected or reported in releases from various industries;
!    The management methods associated with the major
non-hazardous industrial waste generators; and
!    The management practices associated with documented
environmental releases of non-hazardous industrial wastes.
Because of data limitations, EPA could not evaluate all
potential gaps against all of these criteria. Instead, this
step focuses principally on the potential gaps identified in
Steps 3 and 4. Chapter 8 presents this analysis.
Step 8:  Assess Regulatory Programs' Coverage of Potential
Gaps
The second major issue in evaluating potential gaps is the
extent to which the risks are controlled by existing
regulatory or other environmental programs. As noted above,
risk-related gaps were identified solely in terms of their
relationship to non-hazardous industrial waste management,
and not with regard to whether they might be controlled
under regulatory or other programs. Chapter 9 discusses how
major federal and state regulatory programs may address some
of the risks represented by the potential gaps. To the
extent that they are already addressed or could be addressed
more effectively by programs other than the hazardous waste
regulations, the potential gaps may not merit further
attention by the RCRA Subtitle C program.
Step 9:  Present Integrated Evaluation of Nature and Extent
of Potential Gaps
In the final step of the methodology, which is presented in
Chapter 10, EPA integrates and summarizes all of the lines
of evidence relating to particular potential gaps in the
hazardous waste characteristics. The summary is presented in
the form of several tables. This section also reviews the
major data gaps and uncertainties of the analysis.
1.4  Report Outline
This Scoping Study is organized in the same order as the
methodology outlined above.
Chapter 2 characterizes releases from non-hazardous
industrial waste management;
Chapter 3 categorizes risks associated with potential gaps
in the characteristics and reviews the existing
characteristics to identify potential gaps;
Chapter 4 identifies potential gaps associated with non-TC
chemicals;
Chapter 5 identifies potential gaps associated with certain
natural resource damages and large-scale environmental
problems;
Chapter 6 identifies potential gaps in the characteristics
by reviewing how selected states have expanded the TC and
listed wastes that are not listed as hazardous under the
federal program;
Chapter 7 summarizes the potential gaps identified in
Chapters 3 through 6;
Chapter 8 evaluates the extent of the risks presented by
potential gaps;
Chapter 9 discusses how major federal and state regulatory
programs address the risks represented by the potential
gaps; and
Chapter 10 presents an integrated summary evaluation of the
nature and extent of potential gaps and the associated major
analytical limitations and describes the framework that the
Agency will apply in developing a plan for addressing
potential gaps in the hazardous waste characteristics
identified in this Study.
The Study also includes several appendices. Appendix A
describes the individual environmental releases summarized
in Chapter 2. Appendix B discusses several data sources used
to identify environmental releases that were not successful
in finding releases meeting EPA's stringent selection
criteria. Appendix C provides a detailed comparison of the
ICR characteristics to related approaches under other
federal and state programs. Finally, a separate background
document contains detailed information and analysis that
supplements the screening-level risk analysis presented in
Chapter 3 and the identification of "possible" non-hazardous
industrial waste constituents in Chapter 4.
CHAPTER 1. INTRODUCTION  1-1
1.1  Purpose and Requirements of the Hazardous Waste
Characteristics Scoping Study 1-1
1.2  Regulatory Background    1-2
1.3  Approach for Studying Potential Gaps in the Hazardous
Waste Characteristics    1-4
Step 1:  Characterize Releases from Non-Hazardous Industrial
         Waste Management     1-4
Step 2:  Categorize Risks Associated with Non-Hazardous
         Industrial Waste Management    1-4
Step 3:  Review the Existing Characteristics 1-4
Step 4:  Identify Gaps Associated with Non-TC Chemicals
         1-6
Step 5:  Identify Potential Gaps Associated with Certain
         Natural Resource Damages and Large-Scale
         Environmental Problems    1-6
Step 6:  Review State Expansions of TC and State Listings
         1-7
Step 7:  Evaluate the Industries and Waste Management
         Practices Associated with Potential Gaps 1-7
Step 8:  Assess Regulatory Programs' Coverage of Potential
         Gaps  1-8
Step 9:  Present Integrated Evaluation of Nature and Extent
         of Potential Gaps    1-8
1.4  Report Outline 1-8
Exhibit 1-1    Scoping Study Approach   1-5
1 45 Federal Register 33084, May 19, 1980.
2 58 Federal Register 46049, August 31, 1993.
3 55 Federal Register 26987, June 29, 1990.
4 58 Federal Register 46049, August 31, 1993.
Page 1-1
CHAPTER 2. RELEASES FROM NON-HAZARDOUS INDUSTRIAL WASTE
           MANAGEMENT UNITS
This chapter presents the methodology and results of the
Agency's efforts to identify contamination resulting from
the management of non-hazardous industrial wastes. The
Agency prepared a draft report entitled "Hazardous Waste
Characteristics Scoping Study: Environmental Release
Descriptions" which was released for public comment on
September 25, 1996 (see 61 Federal Register 50295). This
chapter summarizes the revised report, incorporating
relevant comments on the draft report.
This chapter is composed of three sections:
!    Section 2.1 discusses the criteria, information
sources, and methodology used to select releases to include
in the report;
!    Section 2.2 summarizes the release descriptions and
presents findings of the study; and
!    Section 2.3 presents the major limitations of the
study.
The environmental release descriptions described in this
chapter are presented in Appendix A of this Scoping Study.
2.1  Methodology
Based on 1985 data, 7.6 billion tons of non-hazardous
industrial waste are generated and managed on-site annually
by 17 major industries in the United States. Despite this
large volume of non-hazardous industrial waste, EPA has few
data concerning the releases, human health impacts, or
environmental damages caused by such wastes. To identify
such releases for purposes of the Scoping Study, the Agency
reviewed readily available information from a wide variety
of data sources. The purpose of this review was not to
estimate risks posed, but rather to characterize releases
due to non-hazardous industrial waste management practices.
This section discusses the criteria and methodology used to
select releases.
2.1.1     Criteria For Selecting Releases
The Agency considered three major factors in judging whether
a release is an appropriate case study for this report. To
be included, a release had to meet all three of the criteria
described below:
1. Source of Release. The source of contamination had to be
a waste management unit that received only non-hazardous
industrial waste. Releases were excluded if:
a. Evidence suggested that the management unit also received
municipal solid waste, special waste, or RCRA hazardous
waste. Many facilities manage municipal, hazardous, and
special wastes in the same waste management units as
non-hazardous industrial waste. Releases from such units
were not included in this report.
b. The source of contamination could not be attributable
solely to a non-hazardous industrial waste management unit.
Releases were excluded where contamination (1) was detected
at or near the facility, but the source of contamination was
unknown; (2) was not from a waste management unit (e.g., was
a product spill); or (3) was from a combination of
non-hazardous industrial waste unit(s) and municipal,
special, or hazardous waste unit(s).
c. The source of contamination was industrial wastewater
discharges that are point source discharges regulated under
Section 402 of the Clean Water Act, as amended.
d. The management method employed would be illegal in most
states today. (Facilities were included if management
practices would be legal today, even if no longer employed
at a particular facility.)
2. Evidence of Damage. For purposes of the study, "damage"
is considered to be a release exceeding one of the levels
described below. All exceedences were examined for purposes
of this scoping study. Exceedences may not actually
represent significant risks. To be included in the Study, a
release from a waste management unit must have caused
contamination at levels of potential concern for that
contaminated medium. Levels of potential concern used for
this criterion were often based on federal or state drinking
water standards for groundwater contamination and
exceedences of background concentrations for soil
contamination. Federal drinking water standards include
maximum contaminant levels (MCLs) and secondary maximum
contaminant levels (SMCLs). State drinking water standards,
which are often stricter than the federal standards, also
were considered. Releases were not included if contaminant
concentrations were above background concentrations but
below levels of potential concern. If at least one
contaminant was detected at concentrations above a federal
or state standard, then data were collected and presented
for all contaminants detected at that site.
3. Test of Proof. Documented evidence must prove that a
damage or danger from a non-hazardous industrial waste
management unit has occurred. Evidence was accepted if it
met one or more of the following three tests:
a. Scientific investigation. Damages were found to exist as
part of the findings of a scientific study. Such studies
include both extensive formal investigations (e.g., in
support of litigation or a state enforcement action) and the
results of technical tests (e.g., monitoring of wells);
b. Administrative ruling. Damages were found to exist
through a formal administrative ruling, such as the
conclusions of a site report by a field inspector, or
through existence of an enforcement action that cited
specific health or environmental dangers; and/or
c. Court decision. Damages were found to exist through a
ruling of a court of law or through an out-of-court
settlement.
2.1.2     Approach For Identifying Releases
The Agency investigated eight major data sources to identify
potential releases:
!    State Industrial D programs;
!    State Superfund programs;
!    Federal Superfund program;
!    Draft EPA report on construction and demolition waste
landfills;
!    Federal RCRA corrective action program;
!    Other federal and state data sources;
!    Newspapers; and
!    Other literature searches.
EPA identified 112 facilities with environmental releases
from 4 of the 8 data sources. As a result, this section
summarizes the methodologies used to investigate only the
four sources that resulted in case studies. Detailed
descriptions of the other four methodologies are presented
in Appendix B. Draft release descriptions were sent to
facility owners/managers for data verification before
inclusion in this final report.
2.1.2.1  State Industrial D Programs
As specified under RCRA Subtitle D, states are the primary
regulators of non-hazardous solid waste, also known as
Subtitle D waste. EPA's role is largely limited to
establishing guidelines for the development and
implementation of state plans, providing technical
assistance, and approving plans that comply with these
requirements. States are responsible for developing and
implementing their own plans. EPA identified states with
potential case studies, then reviewed the state files for
those potential case studies.
The Agency is currently preparing voluntary guidelines on
management standards for non-hazardous industrial wastes. As
part of this effort, in 1995, the Agency contacted
representatives from every state in the continental United
States and asked them to identify known or potential
environmental damages caused by non-hazardous industrial
waste management units. The Agency visited and reviewed
state files at four of the five states that reported the
largest number of potential case studies, California, Texas,
North Carolina, New Mexico, and Wisconsin, and prepared a
report summarizing the results of the visits. The Agency did
not visit California because, at the time, California was
preparing a comprehensive report on its Solid Waste
Assessment Test (SWAT) program, which included detailed
information on environmental releases at non-hazardous
industrial waste disposal sites.
For the Scoping Study, the Agency chose to investigate seven
additional states based on the reported numbers of potential
case studies for these States. Overall, the Agency focused
its review of non-hazardous industrial waste data on 12 of
the 16 states that indicated having at least 10 potential
case studies. The Agency limited its review to these 12
states due to significant time constraints associated with
the Scoping Study.
As the first step in identifying relevant releases or case
studies, the Agency contacted the states by telephone to
discuss the requirements and purpose of the release
descriptions. For states that housed their files regionally,
the Agency contacted each regional office with potential
case studies. After scheduling appointments to review the
state files, the Agency visited states to review and collect
information about the specific releases of non-hazardous
industrial wastes into the environment at concentrations of
concern. The Agency did not visit California. During these
trips, the Agency reviewed readily available documentation
on each potential case study and collected documentation for
only those releases that appeared to meet all three of the
criteria described in Section 3.1.1. Over 80 percent of the
facilities identified as potential case studies were
excluded from further review, primarily because the
facilities co-disposed non-hazardous industrial waste with
municipal, hazardous, or special waste, or because the
environmental damages discovered at the facility could not
be directly linked to a non-hazardous industrial waste
management unit. On an as-needed basis, EPA also made
follow-up contact with state personnel most knowledgeable
about particular sites to obtain additional relevant
information.
To ensure that facility-specific information was accurately
compiled and presented, the Agency contacted the states and
facilities by telephone to ask them to review the draft
release descriptions prepared for this report. The Agency
sent each state and facility their release descriptions,
asked for their written comments on the descriptions, and
incorporated relevant comments.
Review of California's Industrial D Data. In 1984, the
California State legislature passed a law that required
testing of water and air media at all solid waste disposal
sites. The law also required California's State Water
Resource Control Board to rank all solid waste disposal
sites in groups of 150 each, according to the threat these
facilities or sites may pose to water quality. California's
legislation requires site operators to submit a water
quality "solid waste assessment test" (SWAT) report
presenting the following information:
!    An analysis of the surface and groundwater on, under,
and within one mile of the solid waste disposal site to
provide a reliable indication of whether there is any
leakage of hazardous waste constituents; and
!    A chemical characterization of the soil-pore liquid in
those areas that are likely to be affected if the solid
waste disposal site is leaking, as compared to geologically
similar areas near the solid waste disposal site that are
known to not have been affected by leakage or waste
discharge.
To expedite the review of California's Industrial D data,
the Agency obtained a copy of California's Solid Waste
Assessment Test database. The Agency reviewed the database
to identify those facilities believed to manage only
non-hazardous industrial waste and found to have leaked
waste constituents outside the limits of the waste
management unit at levels above California or federal
regulatory standards. California's waste classification
system was used to identify facilities believed to manage
only non-hazardous industrial waste.
The review of Industrial D data from 12 states identified a
total of 104 releases that met the Agency's selection
criteria. Hundreds of potential cases were reviewed to
identify these releases.
2.1.2.2  State Superfund Programs
Abandoned or uncontrolled hazardous substance sites not
addressed by the federal Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) program
may be subject to remediation under the state Superfund
programs. EPA believes that some of these sites may be
contaminated with industrial wastes that would not be
hazardous under the current RCRA Subtitle C requirements.
To expedite the process of identifying relevant sites and to
cover the largest possible percentage of state Superfund
sites, the Agency focused on the states with the largest
programs. These states were identified according to the
Environmental Law Institute's 1993 Analysis of State
Superfund Programs. In July 1996, the Agency identified and
contacted 13 states listed as having at least 1,000 state
Superfund sites. Personnel from each of the 13 states were
asked whether they produce publicly available summaries of
their state Superfund programs. The Agency obtained the most
recent annual state Superfund reports for Missouri, New
Jersey, New York, and Texas and obtained a printout of
California's database for review. Due to the significant
time constraints associated with its analysis, the Agency
did not pursue information from other states, which lacked
detailed, readily available information on their Superfund
program.
Short published site descriptions for nearly 1,000 state
Superfund sites from 5 states, California, Missouri, New
Jersey, New York, and Texas, were reviewed to identify
potential case studies that meet the Agency's selection
criteria. A total of 60 sites were identified as potential
case studies. The Agency contacted the five states by
telephone to discuss the availability of existing
information on those 60 sites. Two states (New York and
Texas) indicated that they had additional information
readily available for review. The Agency visited these
states' Superfund offices to review and the additional
information. The Agency identified one case study from New
York as meeting all of the selection criteria.
2.1.2.3  Federal Superfund Program
The Agency investigated several CERCLA data sources to
identify releases relevant to the Scoping Study. The vast
majority of the CERCLA sites were not expected to meet the
Agency's selection criteria for two reasons. First, the
majority of the sites are contaminated with RCRA hazardous
wastes or with releases or spills from products. These sites
will not meet the Agency's selection criteria for source of
release. Second, most of the CERCLA sites contaminated with
non-hazardous industrial wastes are also expected to be
contaminated with hazardous wastes. Therefore, it is
unlikely that a non-hazardous industrial waste management
unit will be identified as the source of the release at a
CERCLA site.
Due in part to the large number (over 1,300) of CERCLA
National Priority List (NPL) sites and the relatively small
number of sites likely to meet the Agency's three release
selection criteria, the Agency attempted to identify
potential case study sites through telephone discussions
with Regional EPA Superfund personnel and Regional members
of the National Association of Remedial Project Managers and
the National On-Scene Coordinator Association. Although the
Regional Contacts agreed that the Agency should be able to
identify at least a few case studies from the CERCLA
program, they often were unable to identify specific sites.
EPA Superfund staff in Region 4, however, identified two
sites apparently meeting the Agency's selection criteria.
The Agency visited Region 4's Superfund office and reviewed
and copied the relevant files for these two sites. One of
the two sites met the Agency's selection criteria.
The following federal Superfund data sources were also
reviewed; however no releases meeting the Agency's selection
criteria were identified:
!    Record of Decision (ROD) database;
!    CERCLA Natural Resource Damage Claims;
!    CERCLA Characterization Database; and
!    Exposure assessments performed by the Agency for Toxic
Substances and Disease Registry (ATSDR).
2.1.2.4  Construction and Demolition (C&D) Landfill Report
On May 18, 1995, EPA's Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009) published a
draft report entitled Damage Cases:  Construction and
Demolition Waste Landfills. The report, prepared in support
of EPA's rulemaking (60 Federal Register 30963, June 12,
1995) on conditionally exempt small quantity generators
(CESQG), presents information on environmental releases from
construction and demolition (C&D) waste landfills, which
receive materials generated from the construction or
destruction of structures such as buildings, roads, and
bridges. One purpose of the report was to determine whether
the disposal of C&D waste in landfills has threatened or
damaged human health or the environment.
The May 1995 report used three criteria to select potential
C&D waste landfill damage cases.
!    The landfill received predominantly C&D waste, with or
without CESQG waste mixed in. C&D landfills known to have
received significant quantities of municipal, industrial, or
hazardous wastes were excluded.
!    The use of the site as a C&D landfill had to be the
only potential source of the observed contamination. Sites
located near other potential sources of the contamination
such as underground storage tanks were excluded.
!    There was documented evidence of groundwater
contamination, surface water contamination, or ecological
damage at the site. "Contamination" was defined as an
increase in chemical constituent concentrations above
background or an exceedence of an applicable regulatory
standard or criterion attributable to releases from the
site.
In preparing the May 1995 report, the Agency searched for
C&D landfills meeting these criteria using four information
sources:  existing studies of C&D landfills, materials
available through the federal Superfund program,
representatives of EPA Regions, and representatives of state
and county environmental agencies.
The Agency identified 11 environmental releases in the May
1995 report. Although one of the Agency's criteria, as
listed above, was to eliminate C&D landfills that received
significant quantities of municipal or hazardous wastes, 5
of the 11 landfills received municipal, special, or
hazardous wastes. Therefore, for purposes of this report,
the Agency eliminated these five C&D landfill cases.
Eliminating the landfills that managed even small quantities
of municipal, special, or hazardous waste, ensures that the
reported damages were caused by the non-hazardous industrial
wastes, thereby meeting the Agency's selection criteria for
the source of the release.
2.1.3     Release Profile Preparation
The release profiles presented in Appendix A to the Scoping
Study were prepared using a standard format. This format is
discussed below. Because the release profiles were prepared
under significant time constraints using readily available
data, detailed descriptions of the facility, wastes, and
waste management practices could not be developed. The data
often provided only a brief description of the facility and
focused primarily on the results of the environmental
sampling conducted at the facility.
"Facility Overview" discusses the facility's operations, how
long the facility was or has been in operation, the location
of the facility, surrounding land uses, the geologic and
hydrogeologic conditions at the facility, and other
environmental characteristics, provided this information was
available.
"Media Affected" identifies whether the damages are
associated with groundwater, surface water, soil, and/or
ecological receptors.
"Wastes and Waste Management Practices" discusses the
type(s) of wastes generated at the facility and the
practices employed to manage the wastes including
descriptions of the individual waste management units and
groundwater monitoring practices, provided this information
was available.
"Extent of Contamination" discusses the groundwater
contamination, surface water contamination, and/or soil
contamination at the site. Constituents detected in
groundwater or surface water above background levels are
identified and compared to applicable state and federal
standards. The maximum detected concentration for all tested
constituents are given. In reporting exceedences of state or
federal standards, EPA attempted to exclude constituents
whose upgradient or background concentrations were as high
as those in downgradient wells.
"Corrective Actions/Regulatory Actions" discusses any
corrective or regulatory actions that have been recommended,
planned, or taken at the site.
"Source" simply identifies the information source(s) used to
prepare the release profiles. The main source of information
was the facility-specific files located in state offices.
2.2  Results
This section discusses the findings of the review of release
data. It begins by summarizing the 112 documented release
descriptions using the following five categories:
!    Number of cases by state;
!    Number of cases by industry;
!    Number of cases by type of waste management method;
!    Type of media affected; and
!    Type and level of contaminants.
Later chapters of this report also present these and
additional release description data.
2.2.1     Number of Cases By State
The 112 releases described in this chapter were found in 12
states. Because this report is a Scoping Study, these case
studies were not intended to be geographically or
statistically representative of the number of known or
potential releases of non-hazardous industrial wastes
identified by the Agency. Although these case studies are
not statistically or geographically representative, they do
illustrate the type of releases that have occurred from
non-hazardous industrial waste management units in various
parts of the country, as shown in Exhibit 2-1. The case
studies were selected based on the availability of data. Due
to the limited time available to collect data, the Agency
largely focused its efforts on the states with the most
available data on releases from non-hazardous industrial
waste management units. This process identified releases in
most areas of the nation, except the northwest, northern
mountain states, and midwest. The states in these regions
either were unable to identify any or identified few
potential case studies in the Agency's 1995 efforts to
estimate the number of potential releases from non-hazardous
industrial waste management units by state.
Exhibit 2-1
Number of Release Descriptions By State
The available data on facilities that manage non-hazardous
industrial waste indicate that the states addressed in this
report manage some of the largest volumes of non-hazardous
industrial waste. Also, seven of the 12 states represented
in this report are among the 10 states with the largest
number of on-site non-hazardous industrial waste management
units in 1985. Exhibit 2-2 identifies the number of on-site
management units and the volume of waste managed on-site in
states. (See Chapter 8 for further discussion of waste
generation by industry.)
2.2.2     Number of Cases By Industry
The releases documented in this report were from facilities
in 15 2-digit Standard Industry Classification (SIC) codes.
(Industry data are presented at the two-digit level because
more specific classification were not readily available for
many facilities.)  Over 31 percent of the cases involve
Electric, Gas, and Sanitary Services facilities (SIC 49).
All of these facilities are in the refuse system sector (SIC
4953). The top four SIC codes are SIC 49:  Electric, Gas,
and Sanitary Services, SIC 26:  Paper & Allied Products, SIC
28:  Chemical & Allied Products, and SIC 20:  Food & Kindred
Products. These four industry groups represent nearly 75
percent of the releases studied or evaluated in this report.
Exhibit 2-3 identifies the number of cases by industry.
These findings are generally consistent with the Agency's
previous finding that four industries, Paper and Allied
Products (SIC 26), Chemicals and Allied Products (SIC 28),
Petroleum Refining & Related Industries (SIC 29), and
Primary Metal Industries (SIC 33), generated more than 68
percent of the 7.6 billion tons of Industrial D waste
managed on-site in 1985. Although these case studies were
identified based on available data and other selection
criteria, the number of cases identified per industry and
the volume of waste generated per industry appear to be
positively correlated.
2.2.3     Number of Cases By Type of Waste Management Unit
Four major types of land-based treatment and storage units
were identified in the case studies:  landfills, surface
impoundments, land application units, and waste piles.
Exhibit 2-4 presents the number of case studies by waste
management unit. Several cases studies discuss more than one
unit, therefore, the total number of units is higher than
the total number of case studies. Approximately 93 percent
of the case studies involved landfills and/or surface
impoundments. This finding may partly reflect the greater
regulatory attention these units receive from the states,
rather than necessarily imply that these units have more
frequent releases than other types of waste management
units. Over 90 percent of the landfills and 80 percent of
the surface impoundments included in the case studies are
unlined and over 70 percent of the units are no longer being
used to manage non-hazardous industrial wastes.
All 50 states have developed regulations for surface
impoundments. Approximately 90, 46, and 18 percent of the
states have developed regulations specifically for
landfills, land application units, and waste piles,
respectively. The large number of surface impoundments
identified in this report is consistent with a finding of
EPA's 1987 Telephone Screening Survey that slightly more
than half of the facilities that generate and manage on-site
non-hazardous industrial waste managed their wastes in
on-site surface impoundments. The 1987 survey also indicated
that 35 percent of the facilities managed their wastes
on-site in waste piles, 19 percent in landfills, and 18
percent in land application units.
Many states apply their non-hazardous industrial waste
regulations on a site-by-site basis and, therefore, not all
facilities in a state are subject to the same data
collection and recordkeeping requirements. One recent report
indicates that even states with waste pile regulations do
not appear to be actively enforcing control, monitoring, and
closure requirements, which may partly explain the small
number of release descriptions for waste piles.
     The large number of landfills and surface impoundments
in the release descriptions appears consistent with the type
of management units used by the primary industries included
in this report. Reportedly, the food processing industry has
the largest number of non-hazardous industrial waste surface
impoundments and land application units., Other major
industries identified in this report with a large number of
surface impoundments and landfills include the paper,
electric power, chemical, mining, and metal finishing
industries.
2.2.4     Type of Media Affected
Nearly 98 percent of the case studies involved groundwater
contamination. Approximately 31 percent of the case studies
involved contamination of surface water or soil. No case
studies had documented damages from releases to the air and
nearly 30 percent of the case studies affected multiple
media.
The predominance of groundwater contamination is consistent
with the use of groundwater monitoring as the most common
method of detecting releases from waste management units.
Surface water is not as routinely monitored as groundwater.
Surface water sampling is seldom conducted at a facility
until a release is identified. Soil sampling is conducted
much less frequently than groundwater monitoring, and like
surface water sampling, is seldom conducted until a release
has been identified. Few states regulate air emissions from
non-hazardous industrial waste management units. Thus, it is
not surprising that no cases of damage from releases to the
air were documented in the case studies collected for this
report.
2.2.5     Types of Contaminants Released
The number of and types of contaminants routinely analyzed
for in groundwater and other types of samples varies among
states and facilities. Although most facilities included in
the case studies were monitored for a wide range of
constituents, the 20 constituents most commonly detected to
exceed regulatory levels were inorganics. Approximately 50
constituents were detected three or more times, and 70
constituents were detected fewer than three times. Exhibit
2-5 identifies all of the TC constituents that were detected
in the case studies, Exhibit 2-6 presents all of the
constituents with SMCLs that were identified in the case
studies, and Exhibit 2-7 identifies the other constituents
that were detected in at least three case studies. The
exhibits also identify the number of cases where each
constituent was detected, the number of times the
constituent was detected above at least one regulatory
level, the regulatory levels, the average maximum and the
highest maximum detected concentration identified in the
case studies, and the range of the ratio of the highest
detected constituent concentrations to regulatory standards.
Note, only constituents with regulatory standards are
included in Exhibits 2-5, 2-6, and 2-7.
Many inorganic constituents were elevated in groundwater
monitoring wells. Constituents that exceeded state
groundwater protection standards or federal drinking water
standards most frequently were:
!    Iron (49 detections)  !    Cadmium (17 detections)
!    Chloride (32 detections) !    Benzene (16 detections)
!    Manganese (34 detections)     !    Arsenic (15
detections)
!    Sulfate (29 detections)   !    Zinc (13 detections)
!    Lead (22 detections)  !    Aluminum (12 detections)
!    Chromium (21 detections) !    Nitrate (12 detections)
Six of the constituents identified above (iron, chloride,
manganese, sulfate, zinc, and aluminum) have drinking water
standards that are based only on SMCLs.
A total of 25 TC constituents have been detected in the
release descriptions. Exhibit 2-5 identifies 20 of the 25 TC
constituents detected. Five TC constituents
(2,4,6-trichlorophenol, 2,4-dinitrotoluene, o-cresol,
p-cresol, and methyl ethyl ketone) were not included in
Exhibit 2-5 because there were no federal or state standards
established for them. All but 2 of the 20 TC constituents
identified in Exhibit 2-5 (carbon tetrachloride,
1,4-dichlorobenzene) were detected above a federal or state
standard. The majority (85 percent) of the TC constituents
detected above a federal or state standard exceeded the
standards by at least 1 time, 60 percent exceeded by 10
times, 50 percent exceeded by 100 times, 20 percent exceeded
by 1,000 times, 10 percent exceeded by 10,000 times, and
none exceeded by at least 100,000 times. The average maximum
detected concentrations for five of the TC constituents
(arsenic, benzene, selenium, vinyl chloride, and lindane)
exceeded the TC regulatory levels established for these
constituents and the highest maximum detected concentrations
for over half of the identified TC constituents exceed TC
regulatory levels.
All SMCLs or similar state standards, except those for
foaming agents, color, odor, and corrosivity, were violated
by one or more release descriptions. As shown in Exhibit
2-6, the majority (90 percent) of the SMCL constituents
exceeded the standards by at least 1 time, 80 percent
exceeded by 10 times, 40 percent exceeded by 100 times, 20
percent exceeded by 1,000 times, 10 percent exceeded by
10,000 times, and none exceeded by at least 100,000 times.
(Because silver has both a TC level and an SMCL, it is
included in Exhibit 2-5 with the other TC constituents.)
SMCLs are based on aesthetic considerations (e.g., taste and
odor) and are not federally enforceable. Therefore,
exceedences of the SMCLs do not necessarily indicate a
potential danger to human health or the environment. Sixteen
of the case studies (14 percent) were identified based only
on an exceedence of an SMCL. This type of contamination is
discussed further in Chapter 5.
Exhibit 2-7 identifies 24 other constituents that were
detected in the release descriptions. All but four of the
constituents in Exhibit 2-7 (1,1-dichloroethane, nitrogen,
vanadium, and cobalt) were detected above a federal or state
regulatory level. Half (50 percent) of these other
constituents exceeded one of the standards by at least 10
times, 13 percent exceeded by 100 times, 4 percent exceeded
by 1,000 times, and none exceeded by at least 10,000 times.
Constituents managed in landfills were detected in samples
nearly three times more frequently than constituents managed
in surface impoundments. All of the constituents presented
in Exhibits 2-5, 2-6, and 2-7 are associated with wastes
managed in landfills. Approximately 81 percent of the
constituents are associated with both landfills and surface
impoundments, 33 percent are associated with landfills,
surface impoundments, and land application units, 33 percent
are associated with landfills, surface impoundments, and
waste piles, and 12 percent are associated with all 4 waste
management units. The constituents that are associated only
with landfills are antimony, beryllium, boron, cobalt,
cyanides, silver, and thallium.
Exhibit 2-8 identifies the 10 constituents for each of the 6
industries that were identified most frequently in the case
studies. As the exhibit illustrates, inorganics are the most
commonly detected chemicals. The commonly detected
constituents are chloride, pH, iron, lead, total dissolved
solids, manganese, sulfate, magnesium, zinc, and arsenic.
2.3  Major Limitations
The findings presented in this chapter must be interpreted
with care for several reasons, including the limited time
available to collect data, potentially unrepresentative
data, and the Agency's stringent release selection criteria.
Each of these major limitations is discussed in detail
below.
Data were collected under significant time constraints. The
significant amount of data included in this chapter were
collected and analyzed over a four-month period. During this
time the Agency reviewed previously collected data, readily
available databases, and reports; identified and contacted
appropriate state and federal personnel; visited state and
EPA Regional offices; reviewed facility files; prepared case
study summaries; developed a database to analyze the data;
performed QA/QC on the data; sent draft case studies to
states and facilities for review; prepared a draft report
for public review; and incorporated comments into the
report, as appropriate. Due to the time constraints of the
consent decree, the Agency had to carefully prioritize its
efforts and, in doing so, may have eliminated or missed a
number of potential case studies that could have been
included in the report if additional data were available
and/or additional time was spent collecting and reviewing
data.
Data may be unrepresentative and/or out-of-date. In this
report, the Agency did not attempt to estimate the
proportion of non-hazardous management facilities currently
experiencing constituent releases. Due primarily to the
limited time available for data collection and analysis, the
Agency relied upon readily available data. The Agency did
not perform any new sampling or collect new data from
facilities managing non-hazardous industrial wastes. Nor did
the Agency perform a comprehensive review of previously
collected state and federal data for all non-hazardous
industrial waste management facilities. State file reviews
were conducted in one to three days per state and were
limited to those states that indicated having files of
release incidents that met the Agency's selection criteria.
Although the collection of release descriptions is not
statistically representative in any way, these cases are
indicative of the type of releases associated with the
management of non-hazardous industrial waste.
Because only readily available data were analyzed, the data
may not reflect current waste generation and management
practices at the particular facility. Environmental
contamination resulting from waste disposal practices may
take many years to become evident; some releases described
in this report occurred over 20 years ago. The documented
releases may have resulted from particular waste generation
and disposal practices or other conditions that no longer
exist. Specifically, process feedstocks, processing
operations, waste characteristics, and/or waste management
practices may have changed. Facilities may no longer manage
their wastes in unlined units or in environmentally
sensitive areas. Therefore, releases associated with a waste
do not necessarily demonstrate that current waste management
practices or regulations need to change. Conversely, the
failure of a site to exhibit documented damages at present
does not necessarily suggest that waste management has not
or will not cause damage. The Agency, however, believes that
information on dangers posed by past waste management
practices is useful in demonstrating the potential for human
health or environmental damages.
The extent to which the findings can be used to draw
conclusions concerning the relative performance of waste
management practices among states or across industry sectors
is also severely limited by variations in recordkeeping,
monitoring, and other state requirements. Recordkeeping and
monitoring procedures vary significantly among the states.
Several states have complete and up-to-date central
enforcement or monitoring records on facilities that
generate and manage non-hazardous industrial wastes. Where
states have such records, information on releases may be
readily available. Thus, states with the most complete and
accessible monitoring information on non-hazardous
industrial wastes may appear to have more releases than
states with less centralized information management
programs.
Stringent selection criteria. The Agency developed stringent
selection criteria to help focus its data collection efforts
and to avoid any misrepresentation of release incidents. By
focusing solely on releases clearly associated with
non-hazardous industrial waste management units, the Agency
excluded numerous release incidents caused by accidental
releases and spills of products. Although these incidents
may have been caused by hazardous constituents similar to
those managed in non-hazardous industrial waste management
units, and may pose similar hazards, the Agency did not
analyze these cases, largely because of the inability of
RCRA to prevent product releases.
The Agency also excluded release incidents that could not be
linked to specific facilities. Thus, cases of groundwater
and surface water contamination caused by multiple
facilities were excluded because the source of the releases
could not be associated with specific facilities or waste
management units.
The Agency also excluded numerous release incidents
associated with facilities that manage hazardous, municipal,
or special wastes in addition to non-hazardous industrial
waste. Facilities that manage hazardous, municipal, or
special wastes frequently co-dispose of their non-hazardous
industrial wastes in the same or adjacent waste management
units. Due to the close proximity of these different units,
sampling results generally cannot identify the specific unit
associated with the release. Thus, the Agency excluded cases
where non-hazardous industrial waste was managed in the same
or adjacent waste management units as hazardous, municipal,
or special wastes, because the source of the release could
not clearly be associated with the non-hazardous industrial
waste.
CHAPTER 2. RELEASES FROM NON-HAZARDOUS INDUSTRIAL WASTE
           MANAGEMENT UNITS2-1
2.1  Methodology . . . . . . . . . . . . . . . . . .2-1
2.1.1     Criteria For Selecting Releases . . .2-1
2.1.2     Approach For Identifying Releases . .2-3
2.1.2.1  State Industrial D Programs . . .2-3
2.1.2.2  State Superfund Programs. . . . .2-5
2.1.2.3  Federal Superfund Program . . . .2-6
2.1.2.4  Construction and Demolition (C&D) Landfill
         Report     2-6
2.1.3     Release Profile Preparation . . . . .2-7
2.2  Results . . . . . . . . . . . . . . . . . . . .2-8
2.2.1     Number of Cases By State. . . . . . .2-8
2.2.2     Number of Cases By Industry . . . . 2-10
2.2.3     Number of Cases By Type of Waste Management
          Unit    2-11
2.2.4     Type of Media Affected. . . . . . . 2-12
2.2.5     Types of Contaminants Released. . . 2-13
2.3  Major Limitations . . . . . . . . . . . . . . 2-17
Exhibit 2-1    Number of Release Descriptions By State .2-9
Exhibit 2-2    Number of Management Units & Volume of Waste
             Managed On-Site, by State (1985)  2-9
Exhibit 2-3    Number of Case Studies by Industry (SIC). . .
              2-10
Exhibit 2-4    Number of Case Studies By Waste Management
               Unit    2-12
Exhibit 2-5    TC Contaminants Detected in Case Studies.2-14
Exhibit 2-6    Contaminants with SMCLs Detected in Case
               Studies     2-15
Exhibit 2-7    Other Contaminants Detected in At Least Three
              Case Studies    2-16
Exhibit 2-8    Most Common Constituents By Industry. . 2-18
CHAPTER 3. POTENTIAL GAPS ASSOCIATED WITH HAZARDOUS WASTE
           CHARACTERISTICS DEFINITIONS
This chapter examines how well the existing hazardous waste
characteristics address the types of risk they were intended
to address, that is, their target risks. It also addresses
certain other or non-target risks that are closely
associated with the definitions of the hazardous
characteristics. This evaluation of potential gaps begins by
examining the characteristics' definitions and test methods.
This approach is used for two reasons. First, limitations in
the characteristics' effectiveness in reducing their target
risks may themselves constitute important potential gaps.
When the characteristics were promulgated, the Agency
identified physical hazards and acute toxic hazards during
transport and disposal activities, along with chronic
exposure to groundwater contaminated with specific waste
constituents, as being among the most important waste
management risks. Reducing these risks remains an important
goal of the characteristics. Second, this analysis lays the
groundwork for evaluating other potential gaps.
Specifically, risk-based screening methods are used to
evaluate non-target risks from non-ground-water pathways
associated with the toxicity characteristic (TC) analytes.
The findings of that analyses are used to identify potential
gaps associated with a wider universe of known and possible
non-hazardous industrial waste constituents, as discussed in
Chapter 4.
This chapter revisits many of the assumptions and approaches
used to develop the existing hazardous waste
characteristics. The ignitability, corrosivity, and
reactivity (ICR) characteristics are essentially unchanged
since their initial promulgation in 1980. The TC
characteristic was revised in 1990, but has not changed
materially since then. Potential gaps in these
characteristics may be identified if the state of knowledge
about risks addressed by the characteristics has improved
since the characteristics were promulgated; risks that were
not specifically addressed may now be identified as more
important, such as risks from releases to surface water,
inhalation, and indirect pathways and ecological risks. In
addition, the tests used to identify wastes with hazardous
characteristics do not reliably identify all of the risks
the characteristics were intended to address.
The following sections address these issues. Section 3.1
reviews the statutory and regulatory language related to the
types of risks the hazardous waste characteristics were
intended to address and discusses the major categories of
waste management risks addressed and not addressed by the
current characteristics. Sections 3.2 through 3.4 discuss
potential gaps associated with the ignitability,
corrosivity, and reactivity characteristics, respectively.
In addition, a detailed comparison of the ICR
characteristics can be found in Appendix C. Section 3.5
discusses the potential gaps associated with the toxicity
characteristic, including updated risk information on the TC
analytes. Section 3.6 evaluates the toxicity characteristic
leaching procedure (TCLP) as a predictor of constituent
releases and potential risk.
3.1  Types of Risks Addressed by RCRA Hazardous Waste
Characteristics
3.1.1     Statutory and Regulatory Framework
The RCRA hazardous waste characteristics are a vital part of
the comprehensive program of hazardous waste management
established by Subtitle C of RCRA, as amended. Three
provisions of the RCRA statute are particularly relevant to
identifying and expanding the hazardous waste
characteristics (and listing hazardous wastes).
!    First, Section 1004(7) defines hazardous waste as "a
solid waste, or combination of solid wastes, which because
of its quantity, concentration, or physical, chemical, or
infectious characteristics may (A) cause, or significantly
contribute to an increase in mortality or an increase in
serious irreversible, or incapacitating reversible, illness;
or (B) pose a substantial present or potential hazard to
human health or the environment when improperly treated,
stored, transported, or disposed of, or otherwise managed."
This definition indicates the general types of risks that
the hazardous waste management regulations are meant to
address.
!    Second, Section 3001(a) requires EPA to "develop and
promulgate criteria for identifying the characteristics of
hazardous waste, and for listing hazardous wastes, . . .
taking into account toxicity, persistence, and degradability
in nature, potential for accumulation in tissue, and other
related factors such as flammability, corrosiveness, and
other hazardous characteristics. Such criteria shall be
revised from time to time as may be appropriate."
!    Third, Section 3001(b) requires EPA to "promulgate
regulations identifying the characteristics of hazardous
waste, and listing particular hazardous wastes, . . . which
shall be based on the criteria promulgated under [Section
3001(a)] and shall be revised from time to time thereafter
as may be appropriate."  The Section also requires EPA to
"identify or list those hazardous wastes which shall be
subject to the [hazardous waste regulations] solely because
of the presence in such wastes of certain constituents (such
as identified carcinogens, mutagens, or teratogens) at
levels in excess of levels which endanger human health."
In response to the mandate of Section 3001(a), EPA
promulgated two sets of criteria for identifying the
characteristics of hazardous waste in 40 CFR 261.10(a). The
first set of criteria reflects the statutory definition of
hazardous waste and the types of risks that the
characteristics are intended to address:
"(1) The solid waste may
(i) cause, or significantly contribute to, an increase in
mortality or an increase in serious irreversible, or
incapacitating reversible, illness; or
(ii) pose a substantial present or potential hazard to human
health or the environment when it is improperly treated,
stored, transported, disposed, or otherwise managed."
The second set of criteria considers implementation factors:
"(2) The characteristic can be
(i) measured by an available standardized test method which
is reasonably within the capability of generators of solid
waste or private sector laboratories that are available to
serve generators of solid waste; or
(ii) reasonably detected by generators of solid waste
through their knowledge of their waste."
As stated in the May 19, 1980, final rule, EPA adopted the
second set of criteria because the primary responsibility
for determining whether wastes exhibit a characteristic
rests with generators, for whom standard and available
testing protocols are essential. This Scoping Study
addresses these criteria for the current characteristics in
only a general way. The Agency, however, will carefully
consider these factors when deciding the appropriate course
of action for addressing any potential gaps in coverage that
are identified in this Study.
The following sections review the nature of the risks to
human health and environment potentially posed by
non-hazardous industrial waste management. These risks are
associated with physical hazards, acute toxic hazards to
humans, chronic toxic hazards to humans, risk to non-human
receptors, and other hazards. In the discussion below, risks
addressed by the hazardous waste characteristics are
distinguished from those risks not directly or adequately
addressed. The purpose of this section is to develop a
preliminary list of possible gaps in the characteristics. At
this stage, few judgments are made as to the nature and
severity of any potential gaps. Instead, the remainder of
this Report investigates these potential gaps.
3.1.2     Risks Associated with Physical Hazards
Physical hazards include agents that cause direct physical
harm such as thermal burns, wounds, contusions, or eye
injuries, in contrast to agents causing harm through
chemical burns or toxic effects. These hazards are
controlled primarily through the ignitability, corrosivity,
and reactivity (ICR) characteristics. EPA patterned these
characteristics after similar regulations promulgated by the
U.S. Department of Transportation, the National Fire
Protection Association, and other organizations.
The ICR characteristics are intended primarily to protect
waste management and transportation workers against hazards
often associated with hazardous materials. These hazards
include flammability, explosivity, and the propensity to
react violently with other wastes, corrode containers, and
directly injure skin and eyes during transport or management
activities. In addition, these characteristics are intended
to prevent the facilitated release and transport of
hazardous waste constituents. For example, the corrosivity
test is designed, in part, to identify wastes that, because
of their acidity or basicity, may facilitate the
solubilization of metals from wastes. This solubilization
increases the potential impact of metals in groundwater,
thereby increasing the likelihood of risks to human health
via contaminated groundwater.
For the purposes of this Scoping Study, the question is:
What physical risks may arise from the management of
non-hazardous industrial wastes that are currently not
covered by the characteristics?  Several potentially
significant physical risks are not effectively addressed by
the hazardous characteristics. Some of the potential gaps
arise from specific definitions of the ICR characteristics.
These potential gaps, which are discussed in more detail in
Sections 3.2 through 3.4, include:
!    The lack of coverage of corrosive solids;
!    The decision not to address liquids with moderate flash
points;  !    Limitations in the test procedures prescribed
for reactivity; and
!    Potential limitations of pH as an adequate indicator of
corrosivity.
These issues relate to protecting waste management and
transportation workers from physical injuries, except where
explosions or fire might release toxic particulates that
could harm nearby residents. Physical hazards to residents
near management facilities are not considered, based on the
assumption that the general public has limited access to
non-hazardous industrial waste management facilities.
Other physical concerns relate to facilitated pollutant
transport. For example, the corrosivity characteristic was
not intended to address corrosion to liners or any materials
other than steel or to prevent facilitated transport of
organic chemicals through solubilization in discarded
solvents. EPA considered, and decided to omit, a "solvent
override" provision in the 1990 TC rule that would have
classified as hazardous wastes with more than a specified
concentration of hazardous organic solvents. The Agency,
however, left open the possibility that such a provision
could be reconsidered if additional data warrant it. A
related issue is the potential formation of dense and light
non-aqueous phase liquids (DNAPLs and LNAPLs). They are a
potential concern both because they may facilitate pollutant
transport and they have the potential for damaging
groundwater resources and generating high remediation costs.
Section 4.4 discusses the issue of DNAPL and LNAPL
formation.
3.1.3     Acute Toxic Hazards to Humans
The hazardous waste characteristics address some potential
health risks from acute exposures to toxic chemicals. They
limit the potential for release of toxic chemicals during
transportation, storage, treatment, and disposal and
resulting from fires, explosions, or violent reactions.
There are no specific quantitative benchmarks that define
acceptable acute exposure limits, however. The main focus of
the ICR characteristics is on protecting workers, although
the general public is implicitly protected under the
assumption that protecting on-site workers would protect
more distant resident populations as well. Sections 3.2
through 3.4 discuss potential gaps in the ICR
characteristics.
The characteristics were not intended to protect against
other acute systemic toxicity hazards. Direct contact with a
waste, in theory, could result in the absorption of an
acutely toxic dose of a waste constituent from a
non-corrosive waste. The Agency, however, considered this
scenario to be highly improbable for non-hazardous
industrial waste mismanagement. Similarly, acute exposures
via contaminated surface or groundwater are possible, but
were considered much less likely to be important than
chronic toxicity under most circumstances. Because the TC
focuses on the groundwater pathway, with the attendant
long-term transport and dilution of pollutants, EPA assumed
that chronic exposures would be dominant in determining the
potential for adverse health effects. Section 3.5.6
discusses the potential for acute adverse effects of
exposure to the TC analytes and Section 4.6 addresses acute
risks from non-TC constituents.
3.1.4     Chronic Toxicity Risks to Humans
As noted above, EPA intended the TC to be the major vehicle
for controlling chronic health risks, although the
reactivity and corrosivity characteristics also were
intended to prevent releases that facilitate exposure to
waste constituents. Although RCRA Section 3001 identifies a
range of types of toxic effects of concern (toxicity,
carcinogenicity, mutagenicity, and teratogenicity), the
implementation of the TC is limited to 40 chemicals for
which toxicity and groundwater fate and transport data were
available when the Agency revised the characteristic in
1990. In addition, the levels of protectiveness achieved by
the TC leachate concentration standards were determined
using fate and transport models and assumptions that were
current at the time. To the extent that the toxicity data
and groundwater fate and transport models have changed or
improved in the six years since the TC was promulgated, its
expected level of protectiveness may also have changed.
Section 3.5 discusses in detail potential gaps associated
with the level of protectiveness of the TC in light of
recent advances in toxicology and groundwater modeling.
The TC was not intended to address several potentially
important risks. These risks have been identified as
significant contributors to risks from some hazardous waste
constituents and management technologies, and might apply to
non-hazardous industrial waste management as well. Probably
the most important risks potentially not directly addressed
by the TC are associated with exposure pathways other than
groundwater. The TC did not attempt to address these risks
because groundwater was thought to be the dominant risk
pathway for waste management. Upon re-examining potential
non-hazardous industrial waste management and mismanagement
scenarios, however, EPA recognizes that other pathways also
may be important.
One pathway not directly addressed by the TC is the direct
inhalation of volatile or particulate-bound waste
constituents to air from waste management units during
normal operation or after closure. Such exposures to on-site
workers and off-site receptors through direct inhalation may
be significant for some constituents. Other potentially
important pathways include the surface water pathway and
"indirect" pathways arising from air releases (e.g., air
deposition to crops), runoff, and the discharge of
contaminated groundwater to surface water. Also,
bioaccumulation of certain contaminants in aquatic and/or
terrestrial food chains could result in human exposures
through the consumption of contaminated fish, shellfish,
livestock, and game animals. In Section 3.5, a
screening-level risk assessment and other information
clarify the significance of these pathways for the TC
analytes. Chapter 4 extends the screening-level analysis to
non-TC constituents.
3.1.5     Risks to Non-Human Receptors
Neither the TC nor the ICR characteristics were established
specifically to reduce risks to non-human receptors. Such
risk reduction, to the extent that it occurs, is a byproduct
of the control of human health risks. For example, by
preventing pollutant releases from fires and explosions or
reducing pollutant transport, the characteristics protect
the environment as well as human health. The
quantitatively-defined levels of protection incorporated
into the TC leachate concentration limits were based on
human toxicity considerations; they do not consider toxicity
to non-human receptors. While the exposure levels accepted
as protective of human health may be generally protective of
wildlife populations, notable exceptions arise both from the
ecotoxicological properties of some chemicals and from
differences between human and non-human receptor exposure
patterns.
The question therefore can be asked:  To what extent is the
TC protective of ecological receptors?  As in the case of
human health risks, the TC does not directly protect against
risks from chemicals not on the TC list. Similarly, it is
not clear how protective the existing TC levels are for the
various exposure pathways that are most important for
aquatic and terrestrial receptors. In the case of ecological
receptors, as is the case for human health, both direct and
indirect exposure pathways may be significant. These issues
are addressed in more detail in Section 3.5 and Chapter 4 of
this report.
3.1.6     Other Risks Associated with Non-Hazardous
Industrial Waste Management
In establishing the existing hazardous waste
characteristics, the Agency focused exclusively on human
health risks directly associated with local effects of
accidents and on chemical contamination of the environment
in the near vicinity of the management units. In Chapter 5
of this study, EPA has taken a broader view, and has
expanded the scope of the risk identification to include
risks other than those originally considered, even
indirectly, in establishing the hazardous waste
characteristics. These additional categories of risks
include damages to natural resources and contributions to
large-scale environmental problems.
Non-hazardous industrial waste management has the potential
to adversely affect the value or utility of natural
resources, such as wetlands, groundwater, and air, without
posing human health risks. For example, releases from
non-hazardous industrial waste management units have
polluted previously usable groundwater with constituents
generally not considered toxic, such as iron, manganese,
chloride, and total dissolved solids. The regulatory
criteria violated by these releases, such as Secondary
Maximum Concentration Levels (SMCLs) developed under the
Safe Drinking Water Act, are not directly health-related,
but relate instead to the aesthetic properties or usability
of the water. Therefore, even though no health risk is
predicted, the water is rendered unusable and the
environment is thereby damaged. Similarly, odor from
non-hazardous industrial waste management may be seen as an
air resource damage, reducing the quality of life for
affected individuals, even in the absence of direct health
effects.
The last category of risks are associated with the possible
contribution of non-hazardous industrial waste management to
large-scale environmental problems, including:
!    Air deposition to the Great Waters;
!    Damages from airborne particulates;
!    Global climate change;
!    Potential damages from endocrine disruptors;
!    Red tides;
!    Stratospheric ozone depletion;
Tropospheric ozone and photochemical air pollution; and
!    Water pollution.
The possible relationship between non-hazardous industrial
waste management and these risks is less clear than for the
previously identified risks.
As summarized in Exhibit 3-1, Section 3.1 has presented an
intentionally broad inventory of potential risks to human
health and the environment associated with the management of
non-hazardous industrial wastes not currently identified as
hazardous. This list provides a catalogue of risks for
evaluation against the existing characteristics in the rest
of this chapter and the following chapters.
3.2  Ignitability Characteristic
This section describes potential gaps related to the
definition of the RCRA ignitability characteristic and its
test methods. The basic approach taken in identifying
potential gaps for ignitability as well as for corrosivity
and reactivity was to review the original 1980 rulemaking
record and to compare the characteristic to approaches taken
to controlling similar hazards under other regulatory
schemes, including the U.S. Department of Transportation's
(DOT's) hazardous materials regulations, the U.S.
Occupational Safety and Health Administration's (OSHA's)
worker health hazards standards, and state hazardous waste
management standards.
3.2.1     Definition of Ignitability
The ignitability characteristic is intended to "identify
wastes capable of causing fires during routine
transportation, storage and disposal, and wastes capable of
exacerbating a fire once started."  These risks include
generally recognized fire hazards to waste management and
transportation workers, such as burns and inhalation smoke
or fumes, and the potential generation and facilitated
transport in air of toxic particulates and fumes that could
harm the general public. According to 40 CFR 261.21, a solid
waste exhibits the characteristic of ignitability if a
representative sample of the waste has any of the following
properties:
!    Is a liquid, other than an aqueous solution containing
less than 24 percent alcohol by volume and has flash point
less than 60oC (140oF), as determined by:
--   A Pensky-Martens Closed Cup Tester, using the test
method specified in ASTM Standard D-93-79 or D-93-80
(incorporated by reference, see ' 260.11),
--   A Setaflash Closed Cup Tester, using the test method
specified in ASTM standard D-3278-78 (incorporated by
reference, see ' 260.11), or
--   An equivalent test method approved by the Administrator
under procedures set forth in '' 260.20 and 260.21;
!    Is not a liquid and is capable, under standard
temperature and pressure, of causing fire through friction,
absorption of moisture or spontaneous chemical changes and,
when ignited, burns so vigorously and persistently that it
creates a hazard;
!    Is an ignitable compressed gas as defined in 49 CFR
173.300 and as determined by the test methods described in
that regulation or equivalent test methods approved by the
Administrator under '' 260.20 and 260.21; or
!    Is an oxidizer as defined in 49 CFR 173.151.
3.2.2     Potential Gaps Related to Definition of
Ignitability
Liquids with flash point at or above 140EF not covered. The
RCRA ignitability characteristic includes liquid wastes with
flash point less than 60oC (140oF). When promulgating the
original characteristic, EPA acknowledged choosing a
definition for ignitable liquid wastes that excluded some
potential wastes that would meet the definition of hazardous
materials under DOT regulations. The DOT definition of
flammable liquid includes liquids with flash point not more
than 60.5EC (141EF), or any material in liquid phase with a
flash point at or above 37.8EC (100EF) that is intentionally
heated and offered for transportation or transported at or
above its flash point in a bulk packaging. The DOT
definition of combustible liquid includes liquids with flash
point above 60.5EC (141EF) and below 93EC (200EF). Thus, the
RCRA ignitability characteristic covers wastes that would be
classified as DOT flammable liquids, but not DOT combustible
liquids. Consistent with DOT regulations, OSHA includes such
"combustible" liquids in its definition of health hazard,
and Rhode Island regulates them as hazardous wastes.
In a background document supporting the promulgation of the
original characteristics, EPA stated that the RCRA
ignitability flash point limit of 140oF reflects conditions
likely to be encountered during routine waste management. In
support of this conclusion, the Agency referenced seven
studies documenting temperatures and conditions at waste
management units. The information available to the Agency at
the time was limited, however. Furthermore, two of these
studies reported temperatures of greater than 140oF. One
study reported temperatures of approximately 160oF near the
surface of a landfill, noting that aerobic conditions near
the surface of landfills often result in relatively high
temperatures.
Data are still limited regarding whether temperatures
greater than 140oF are encountered during non-hazardous
industrial waste management, in what situations and how
frequently this occurs, and what maximum temperatures are
reached (particularly in hotter regions of the nation). One
relevant issue is whether temperatures exceeding 140oF may
be encountered during mismanagement (as opposed to routine
waste management). Examples of possible mismanagement
scenarios for ignitable wastes include:
!    Wastes stored in closed, heat-containing facilities
(e.g., metal sheds, upper floor warehouse spaces, or metal
trucks) in hot climates and/or sunlight; and
!    Wastes mixed in waste management units in a manner that
might generate heat through chemical reactions, especially
in the presence of hot climate or sunlight.
No information is readily available regarding the universe
of "combustible" industrial wastes currently being managed
as non-hazardous. Nevertheless, some liquid materials with
flash points generally in this range can be identified, as
shown in Exhibit 3-2. Examples include certain alcohols, low
molecular weight esters, ethylene glycol ethers, kerosene,
jet fuels, certain petroleum byproducts, many "tints and
paints," and individual chemicals including benzaldehyde,
benzonitrile, and bromobenzene. If these materials are
disposed of or are present in wastes, the wastes may be
combustible, in spite of not being hazardous by the
ignitability characteristic. In addition, mixtures of
materials of differing flash points may fall into this
category.
Exclusion for aqueous liquids containing less than 24
percent alcohol may warrant reexamination. At the time of
the original rulemaking, some commenters argued that liquid
wastes such as wine and some latex paints that exhibit low
flash points because of their alcohol content do not sustain
combustion because of the high percentage of water and
therefore should not be designated as characteristically
hazardous waste. EPA agreed and excluded from the
ignitability characteristic aqueous solutions containing
less than 24 percent of alcohol by volume. A similar
exclusion is found in DOT regulations. EPA stated that it
hoped "to undertake further study to determine whether
another exclusion limit is more appropriate and to evaluate
tests which might be capable of identifying wastes which
exhibit this phenomenon."  EPA also intended to evaluate
possible supplemental test methods to evaluate flammability
hazards for these types of wastes.
The exclusion for aqueous liquids containing alcohol has
caused confusion during implementation and enforcement
concerning whether it applies only to ethanol or more
broadly to all alcohols. The exclusion also focuses on
aqueous alcohol solutions, rather than on the underlying
target of liquids with low flash points that do not sustain
combustion. (Tests for sustained combustion are now
available:  ASTM has methods D-4206 and D-4207.)  In
addition, the rationale that certain liquids should not be
considered ignitable if they do not sustain combustion may
not be valid where an excluded aqueous solution could flash
and ignite a co-managed non-hazardous waste that would
sustain combustion.
References to DOT regulations are outdated. The ignitability
characteristic refers to a DOT definition of ignitable
compressed gas (49 CFR 173.300) that has been withdrawn.
Current DOT regulations at 49 CFR 173.115 define flammable
gas, which is any material that is a gas at 20EC (68EF) or
less and 101.3 kPa (kilopascals equal to 14.7 pounds per
square inch) of pressure. The complete definition includes
any material that has a boiling point of 20EC (68EF) or less
at 101.3 kPa (14.7 psi)) that (1) is ignitable at 101.3 kPa
(14.7 psi) when in a mixture of 13 percent or less by volume
with air; or (2) has a flammable range at 101.3 kPa (14.7
psi) with air of at least 12 percent regardless of the lower
limit. Likewise, the term oxidizer is no longer defined at
49 CFR 173.151. It is now found at 49 CFR 173.127. These
out-of-date citations constitute a potential gap because
they may cause regulatory confusion and misinterpretation
and thereby may impede efficient and effective compliance
and enforcement.
3.2.3  Potential Gaps Related to Ignitability Test Methods
No test method is specified for non-liquids. The
ignitability characteristic does not specify a test method
for non-liquid wastes. In a background document supporting
the original rulemaking, EPA stated that non-liquid wastes
may present a hazard by virtue of their capacity to ignite
and burn as a result of friction, moisture absorption, or
spontaneous reaction under the normal temperatures and
pressures encountered in waste management. The Agency noted
that such wastes are akin to reactive wastes and can
directly injure workers or others as a result of fire,
induced explosions, or induced generation of toxic gases at
almost any point in the waste management process. Examples
of potential ignitable non-liquid wastes include soils
highly contaminated with gasoline or other ignitable
substances and sorbents used to cleanup spills of ignitable
substances.
In explaining the final rulemaking, the Agency stated that,
although "EPA would have preferred providing a test method
for identifying ignitable solids, it has determined . . .
that there are no test methods capable of accurately
identifying the small class of ignitable solids to which its
regulation is directed. EPA is presently working with the
Department of Transportation and other organizations to
correct this deficiency."  Since then, EPA has identified a
test method that may be  suitable for identifying ignitable
solids. Method 1030 ("Ignitability of Solids") has been
proposed for inclusion in the Third Edition of the EPA test
methods manual "Test Methods for Evaluating Solid Waste,
Physical/Chemical Methods," EPA Publication SW-846. The
method is appropriate for pastes, granular materials, solids
that can be cut into strips, and powdery substances.
3.3 Corrosivity
3.3.1     Definition of Corrosivity
According to 40 CFR 261.22, a solid waste exhibits the
characteristic of corrosivity if a representative sample of
the waste has either of the following properties:
!    Is aqueous and has a pH less than or equal to 2 or
greater than or equal to 12.5, as determined by a pH meter
using Method 9040 in "Test Methods for the Evaluation of
Solid Waste, Physical/Chemical Methods," incorporated by
reference in ' 260.11; or
!    Is a liquid and corrodes steel (SAE 1020) at a rate
greater than 6.35 mm (0.250 inch) per year at a test
temperature of 55oC (130oF) as determined by the test method
specified in NACE (National Association of Corrosion
Engineers) Standard TM-01-69 as standardized in "Test
Methods for the Evaluation of Solid Waste, Physical/Chemical
Methods," EPA Publication SW-846, as incorporated by
reference in ' 260.11.
The first part of this definition encompasses wastes
exhibiting low or high pH, which "can cause harm to human
tissue, promote the migration of toxic contaminants from
other wastes, react dangerously with other wastes, and harm
aquatic life."  Specifically, the Agency identified skin and
eye damage to transporters who are directly exposed to the
waste as a primary focus of this characteristic. The pH
limits also were intended to address the potential
solubilization of heavy metals allowing migration to
groundwater, reactions with incompatible wastes resulting in
fires, explosions, generation of flammable or toxic gases,
generation of pressure inside vessels, and the dispersal of
toxic vapors, mists, and particulates.
The other part of the corrosivity characteristic relates to
the corrosivity of waste to steel containers. The Agency
identified this aspect of corrosivity as a hazard because
"wastes capable of corroding metal can escape from the
containers in which they are segregated and liberate other
wastes."  The consequences of liberating wastes from
containers during transportation or storage include harm
from direct contact, violent reactions, and the release of
waste components to the environment.
3.3.2     Potential Gaps Related to Definition of
Corrosivity
Non-liquids are not covered. The current RCRA corrosivity
characteristic is limited to liquids. Other regulatory
programs, however, also cover corrosive non-liquids. For
example:
!    DOT regulates corrosive liquids and solids as hazardous
materials;
!    The OSHA definition of health hazard includes all
corrosives regardless of physical form;
!    The Basel Convention definitions of hazardous materials
are not limited to liquids; and
!    At least four states (California, New Hampshire, Rhode
Island, and Washington) include non-aqueous wastes in their
definitions of corrosivity. New Hampshire and Rhode Island
specifically include corrosive gases as well as corrosive
solids.
The states that include non-liquids in their corrosivity
characteristics specify mixing the non-aqueous waste with
water and then testing for pH. The rationale for this
approach is that the waste is likely to come into contact
with water during land-based management. In addition, EPA
has developed Method 9045 (Soil and Waste pH), which can be
used to test some corrosive solid wastes. Finally, Method
1120 (Dermal Corrosion) may be applied to solids, liquids,
and emulsions (see additional discussion below under
"potential gaps related to corrosivity test methods").
pH limits may not cover some hazards. EPA originally
proposed pH limits of 12.0 or greater and 3.0 or less, and a
majority of commenters argued that these limits were too
stringent. The commenters argued that the limit of 12.0 or
greater would regulate as hazardous many lime-stabilized
wastes and sludges, thereby discouraging use of a valuable
treatment technique, and that the pH limit of 3.0 or less
would regulate a number of substances generally thought to
be innocuous (e.g., cola drinks) and many industrial
wastewaters prior to neutralization. EPA agreed with these
commenters and promulgated pH limits of 12.5 or greater and
2.0 or less in the 1980 final rule.
The more stringent proposed pH limits were based on studies
of eye tissue damage. These studies indicated that pH
extremes above 11.5 and below 2.5 generally are not
tolerated by human corneal tissue. EPA decided that basing
pH limits on eye tissue damage was unnecessarily
conservative. Thus, eye damage is a hazard not fully
addressed by the corrosivity characteristic.
The corrosivity characteristic also was intended to prevent
harm to ecological receptors caused by the release of
hazardous wastes with high- or low-pH. In discussing aquatic
life in the original background document, EPA noted that the
optimum pH range for freshwater fish is 6.5 to 9.0 and that
an increase or decrease of 2 pH units beyond the optimum
range causes severe effects. Levels of pH of 11.0 or greater
and 3.5 or less are fatal to all species of fish. EPA also
noted that altering surface water pH can reduce the
productivity of food organisms essential to fish and
wildlife. The pH limits of the corrosivity characteristic
(2.0 and 12.5) are well beyond the safe range for aquatic
life, but wastes presumably would be significantly diluted
before the point of exposure to aquatic life. EPA did not
conduct a risk assessment of such potential hazards (e.g.,
modeling the pathway of waste released to surface water and
exposure to aquatic life) and thus it is not known under
what circumstances high- or low-pH wastes could cause harm
to aquatic receptors.
Corrosion of materials other than steel is not directly
addressed. In the second part of the corrosivity
characteristic, EPA uses steel corrosion as an indicator of
corrosivity. EPA adopted this aspect of corrosivity because
"wastes capable of corroding metal can escape from the
containers in which they are segregated and liberate other
wastes."  EPA adopted DOT's corrosion standard, noting that
the rate at which a waste corrodes a material commonly used
in container construction (low carbon steel) is a suitable
measure of its hazardousness.
The reliance on the steel corrosion rate may create a
potential gap if there are plausible mismanagement scenarios
where wastes are stored, transported, or disposed in
containers made from materials more easily corroded than low
carbon steel (e.g., plastic by organic solvents) or are
disposed in solid waste management units lined with
materials such as clay or synthetics. Also, there may be a
potential gap in the characteristic if waste management
scenarios result in conditions where wastes are subject to
higher temperatures than the 130oF test temperature.
Solubilization of hazardous constituents. The corrosivity
characteristic also was intended to address the potential
for high- and low-pH materials to solubilize potentially
toxic waste constituents. EPA offers the example that a drop
in pH from 4.0 to 2.0 increases the solubility of red
mercury oxide or chromium hydroxide in water approximately
100 times. The general concern is for inorganic ions that
may be converted to more soluble species. This
characteristic does not address the potential solubilization
of organic constituents by organic liquids such as solvents,
nor does it address the formation of non-aqueous phase
liquids (NAPLs) by such materials. EPA considered including
a solvents "override" in the TC characteristic, but did not
do so. The solvents override would have caused wastes with
high concentrations of solvents to be classified as
hazardous on the basis of potential NAPL formation. The
issue of NAPL formation is discussed in more detail in
Chapter 5.
Lack of coverage of sensitizers and irritants. At least two
types of materials that may pose potential hazards to humans
through direct contact are not included in the corrosivity
characteristic or any other characteristic:  irritants and
sensitizers. OSHA includes irritants in its definition of
health hazard and defines irritant as a material that is not
corrosive, but which causes a reversible inflammatory effect
on living tissue by chemical action at the site of contact.
A chemical is a skin irritant if, when tested on the intact
skin of albino rabbits by the methods of 16 CFR 1500.41 for
four hours exposure or by other appropriate techniques, it
results in an empirical score of five or more. A chemical is
an eye irritant if so determined under the procedure listed
in 16 CFR 1500.42 or other appropriate techniques. (See 29
CFR 1910.1200.)
OSHA also includes sensitizers in its definition of health
hazard. A sensitizer is defined as a material that causes a
substantial proportion of exposed people or animals to
develop an allergic reaction in normal tissue after repeated
exposure to the chemical. (See 29 CFR 1910.1200.)
This analysis did not identify any specific non-hazardous
industrial wastes that are irritants or sensitizers.
Irritants and sensitizers, however, are common categories of
materials and these properties are often identified in
laboratory testing of materials. A major issue regarding
this potential gap is whether any irritants and/or
sensitizers pose a hazard in wastes that reaches the
statutory level of hazard intended to be covered by RCRA
Subtitle C.
3.3.3     Potential Gaps Related to Corrosivity Test Methods
Use of pH as an indicator has limitations. EPA chose pH as a
measure of corrosivity because "wastes exhibiting low or
high pH can cause harm to human tissue, promote the
migration of toxic contaminants from other wastes, react
dangerously with other wastes, and harm aquatic life."  The
ability of some substances to damage human tissue, however,
may not be adequately indicated by a pH measurement. Other
regulatory and advisory bodies (e.g., DOT, OSHA, Basel
Convention) use criteria based on full thickness destruction
of human skin.
Since the original rulemaking in 1980, Method 1120 (Dermal
Corrosion) has been developed commercially. The dermal
corrosion assay system is an in vitro test method which
determines the corrosive potential of a substance toward
human skin. It can be used to test liquids (aqueous or
non-aqueous), solids (water soluble or insoluble), and
emulsions. Method 1120 is essentially the same method that
DOT uses. It replaced previous tests (e.g., Draize test)
that used live animals with a test that uses a proprietary
synthetic pig collagen material.
3.4 Reactivity
3.4.1     Definition of Reactivity
The reactivity characteristic is "intended to identify
wastes, which because of their extreme instability and
tendency to react violently or explode, pose a problem at
all stages of the waste management process."  This
characteristic was intended to reduce physical risks to
transportation and disposal workers and to avoid incidents
that could result in the release of toxic constituents into
the air consequent to an explosion or violent reaction. 40
CFR 261.23 states that a solid waste exhibits the
characteristic of reactivity if a representative sample of
the waste has any of the following properties:
!    Is normally unstable and readily undergoes violent
change without detonating;
!    Reacts violently with water;
!    Forms potentially explosive mixtures with water;
!    When mixed with water, generates toxic gases, vapor, or
fumes in a quantity sufficient to present a danger to human
health or the environment;
!    Is a cyanide or sulfide bearing waste which, when
exposed to pH conditions between 2 and 12.5 can generate
toxic gases, vapors or fumes in a quantity sufficient to
present a danger to human health or the environment;
!    Is capable of detonation or explosive reaction if it is
subjected to a strong initiating source or if heated under
confinement;
!    Is readily capable of detonation or explosive
decomposition or reaction at standard temperature and
pressure; or
!    Is a forbidden explosive as defined in 49 CFR 173.51,
or a Class A explosive as defined in 49 CFR 173.53 or a
Class B explosive as defined in 49 CFR 173.88.
3.4.2     Potential Gaps Related to Definition of Reactivity
The Definition is broad and lacks specificity. In discussing
the reactivity characteristic in the 1980 final rule, EPA
stated that "the definition was intended to identify wastes
which, because of their extreme instability and tendency to
react violently or explode, pose a problem at all stages of
the waste management process."  EPA noted that the
reactivity characteristic encompasses a diverse class of
physical properties and effects and overlaps somewhat with
the ignitability characteristic.
Some commenters argued that the definition was vague. They
advocated using a quantitative  definition accompanied by
testing protocol(s). EPA responded that "the prose
definition should provide generators with sufficient
guidance to enable them to determine whether their wastes
are reactive."  EPA argued that most generators whose wastes
are dangerous because they are reactive are well aware of
this property and such wastes usually are generated from
reactive feedstocks and/or processes producing reactive
products or intermediates. EPA further stated that problems
posed by reactivity appeared to be confined to a fairly
narrow category of wastes.
Theoretically, the reactivity characteristic could be
clarified and made consistent with other programs
(especially DOT) by developing more specific definitions of
general terms such as "normally unstable," "violent change,"
"potentially explosive," "reacts violently with water,"
"readily capable of detonation," and so forth. Other
programs include more specific definitions. For example, as
shown in Exhibit 3-3, DOT has adopted definitions of
spontaneously combustible material and dangerous when wet
material, which could be used to clarify the RCRA
characteristic. Specifically, DOT identifies an ignition
time and violent reaction rate. Likewise, OSHA defines
pyrophoric, unstable reactive, and water reactive,
specifying reactive conditions such as shocks, pressure, and
temperature which define the characteristic. The Basel
Convention also defines similar terms.
References to DOT regulations are outdated. Forbidden
explosive are no longer defined in 49 CFR 173.51. The
current DOT regulations define forbidden explosives at 49
CFR 173.54. Other explosives are defined at 49 CFR 173.50.
49 CFR 173.88 no longer exists.
3.4.3     Potential Gaps Related to Reactivity Test Methods
Reactivity characteristic lacks test method(s). When the
Agency promulgated the reactivity characteristic in 1980, no
available tests were identified for use in defining the
reactivity characteristic because:
!    They were too restrictive and were confined to
measuring how one specific aspect of reactivity correlates
with a specific initiating condition or stress.
!    Testing the reactivity of a sample does not necessarily
reflect reactivity of the waste, because reactivity varies
with properties including mass and surface area.
!    Most available tests required subjective interpretation
of results.
!    Existing methods were not developed for testing wastes.
Although EPA has identified a test method (Method 9010) for
reactive sulfide and/or cyanide bearing wastes, the Agency
has not identified suitable test methods to fully define the
reactivity characteristic.
3.5 Potential Gaps Associated with the Toxicity
Characteristic
3.5.1     Definition of Toxicity Characteristic
The toxicity characteristic was designed by EPA to reduce
risks to public health from chronic exposures to groundwater
contamination caused by releases of toxic waste
constituents. The Agency found "persuasive evidence that the
contamination of groundwater through the leaching of waste
contaminants from land disposed wastes is one of the most
prevalent pathways by which toxic waste constituents migrate
to the environment."  The legislative history of RCRA and
EPA's case studies of damages from hazardous waste
management were cited as support for focusing the toxicity
characteristic exclusively on groundwater pathway risks.
EPA originally listed 14 contaminants as part of the
toxicity characteristic. Subsequently, EPA added another 26
substances to the list, as shown in Exhibit 3-4. These 40 TC
chemicals were selected because:
!    The chemicals were included on the 40 CFR Part 261
Appendix VIII list of hazardous waste constituents that have
been "shown to have toxic, carcinogenic, mutagenic, or
teratogenic effects," and
!    Appropriate chronic toxicity information had been
developed and adequate fate and transport data were
available to allow the modeling of groundwater fate and
transport for each constituent.Thus, EPA found these
chemicals to be among those posing the greatest risk to
humans from chronic groundwater exposure.
The remainder of Section 3.5 evaluates the TC in five steps:
!    Section 3.5.2 examines whether new data on the toxicity
and persistence of TC analytes and updated groundwater
transport modeling techniques would result in allowable TC
leachate concentrations different from those established in
1990.
!    Section 3.5.3 presents screening-level exposure and
risk modeling methods and results that are used to evaluate
whether the current TC chemicals could pose risks to human
health and environmental receptors through the inhalation
pathway.
!    Sections 3.5.4 and 3.5.5 evaluate potential risks from
TC chemicals to human health through surface water pathways
and indirect pathways, respectively. These risks are
evaluated by comparing toxicity and fate and transport
values to defined risk-related criteria, both singly and in
combination, and by reviewing the results of the Agency's
multipathway risk modeling for the analytes that was
performed as part of the proposed Hazardous Waste
Identification Rule (HWIR-Waste) development.
!    Sections 3.5.6 and 3.5.7 evaluate the potential for
acute adverse health effects of exposures to TC analytes and
potential risks to ecological receptors from TC analytes,
respectively.
3.5.2     Changes in Groundwater Pathway Analysis
This section of the Scoping Study explores two issues
related to the current TC regulatory levels:  (1) whether
new toxicity data indicate a potential need to revise the
regulatory levels; and (2) whether, in light of recent
developments in groundwater modeling techniques, the current
dilution and attenuation factor (DAF) value of 100 still
provides a reliable basis for assuring that human health is
protected against risks from groundwater exposures to TC
chemicals.
Revisions to MCLs and Toxicity Criteria
The toxicological bases for the establishment of TC analyte
regulatory levels were chronic toxicological and
health-based regulatory criteria that were current at the
time of promulgation. These included Safe Drinking Water Act
Maximum Contaminant Levels (MCLs), Reference Doses (RfDs),
and Risk-Specific Doses (RSDs) based on ingestion pathway
Cancer Slope Factors (CSFs). For almost all of the TC
analytes, these values have not changed since 1990. The few
changes have included:
!    A reduction in the RfD for p-cresol by a factor of ten
and the withdrawal of the MCL of 50 ug/l for lead and its
replacement with an Action Level of 15 ug/l. For cresol and
lead, the reductions in RfDs and promulgation of Action
Levels indicate that the toxicological evaluation of these
chemicals has changed such that the TC regulatory levels may
be less protective than was originally intended. The changes
for both of these analytes were an order of magnitude or
less.
!    The withdrawal of the MCL for silver, with its
replacement by an SMCL at the same value. This change simply
means that the critical toxic effect for silver (argyria,
which is the collection of dark pigment in the skin and
mucous membranes) has been downgraded from a health effect
to a cosmetic effect.
!    In addition, the RfD for pentachlorophenol has been
reduced from 2 mg/l to 3x10-2 mg/l. More importantly, since
the TC was revised, the Agency has promulgated a cancer
slope factor for this compound, which is a suspect human
carcinogen. Thus, the critical toxic endpoint has been
changed from non-cancer to cancer induction. The
promulgation of the Cancer Slope Factor implies that a much
lower TC regulatory level (about 1000 times lower) would be
needed to achieve the same level of protection against
cancer risks as originally intended when the TC was
promulgated.
Advances in Groundwater Modeling
To develop the existing TC regulatory levels, the Agency
used the EPAMCL model to estimate the likely extent of
dilution after the release of waste constituents from waste
management units during their transport to the nearest
drinking water wells. These calculations were conducted for
municipal solid waste landfills and Subtitle D surface
impoundments, taking into account the geochemical properties
of the constituents, the size and configuration of the
units, the vadose zone and groundwater regimes beneath the
units, and the distribution of distances in the downgradient
direction to the nearest drinking water well. Groundwater
regimes were defined using distributions of transport
parameter values typical of conditions throughout the United
States. Receptor wells were assumed to be in the groundwater
plume at a distribution of distances derived from a Subtitle
D facility survey. Simulation methods were used to derive
estimates of dilution-attenuation factors (DAFs) for each
constituent and each type of waste management unit. After
reviewing the results, the Agency elected to calculate
acceptable leachate concentrations (regulatory levels) for
each TC analyte using a single DAF value of 100. In other
words, the threshold leachate concentration of each analyte
above which wastes would be identified as TC hazardous was
set equal to allowable drinking water concentration or other
benchmark (10-5 cancer risk or Hazard Quotient (HQ) = 1.0)
for the analytes multiplied by 100.
Since the TC was promulgated, the Agency has continued to
use the same general approach to evaluate the groundwater
transport of pollutants in developing RCRA regulations. The
exact techniques used in this modeling, however, have
changed significantly. In recent rulemakings, the Agency has
used an updated version of the EPAMCL model, known as
EPACMTP, to derive constituent-specific DAFs for a wide
range of pollutant releases from hazardous and non-hazardous
waste management units. This model employs many of the same
basic transport algorithms as the EPAMCL, with several
important differences, including the following:    !    The
EPACMTP model uses a detailed metals speciation model
(MINTEQA) to estimate leachate concentrations from wastes of
defined ionic composition, whereas the EPAMCL model did not
employ such a model;
!    The EPACMTP, unlike EPAMCL, can model the adsorbtion to
soil and transformation of organic waste constituents by
hydrolysis into more toxic (or less toxic) transformation
products;
!    The EPACMTP directly simulates the interface between
the saturated and vadose zones;
!    The EPACMTP model can simulate groundwater mounding
under management units, whereas the EPAMCL could not; and
!    The EPACMTP model provides more flexibility in modeling
finite, versus infinite, source terms.
Recent applications of the model also used somewhat
different assumptions regarding waste and facility
characteristics, hydrogeological regimes, climatology, and
receptor locations than those used in the development of the
TC. Therefore, it is not possible, except in a very general
way, to simply compare the DAF value used in establishing
the TC allowable leachate concentrations with the
constituent-specific DAF values for the same constituents
derived in the subsequent analyses. In addition, DAF values
derived for metals using the EPACMTP vary with the initial
concentration of the constituent in the waste, because the
model incorporates saturable binding and transport
phenomena. In contrast, the DAFs derived using the EPAMCL
model are concentration-invariant under most conditions.
Recently, EPA has employed the EPACMTP model in two major
regulatory development efforts.
!    EPA applied the model in its development of proposed
risk-based exit levels for the Proposed Hazardous Waste
Identification Rule for Process Waste (HWIR-Waste). In that
analysis, EPACMTP was used to back-calculate concentrations
of constituents in wastes and in waste leachate
corresponding to specific risk levels through groundwater
exposures. The Agency is currently revising the proposed
HWIR-Waste exit level groundwater risk modeling methods in
response to comments from the Science Advisory Board and
from other technical reviewers. Thus, the results of this
modeling presented in this Scoping Study should be regarded
as preliminary.
!    In the Phase IV LDR regulatory development effort for
mineral processing wastes, the model was used to derive
constituent-specific DAFs for mineral processing wastes
disposed of in surface impoundments and waste piles. The
DAFs were then used to derive groundwater pathway risk
estimates for exposure to waste constituents.
The results of these analyses have been used to evaluate the
extent to which changes in modeling techniques may have
affected the assessment of groundwater fate and transport
relative to the assessment used to derive the TC regulatory
concentrations. As noted previously, a simple comparison of
DAF values and/or calculated risk levels from the different
modeling efforts is not possible without further analysis
since the more recent modeling employs different groundwater
transport models and different assumptions regarding
facility characteristics, groundwater regimes, and receptor
locations. In the case of the mineral processing risk
assessment, for example, DAF values were derived
specifically for facility sizes representative of the
mineral processing industry, rather than Subtitle D
management units. In addition, groundwater modeling was
performed using climatologic data primarily from drier
regions where many mineral processing facilities are
located. While Subtitle D facilities were used to calculate
releases for the HWIR-Waste proposal, the receptor wells
were assumed to be distributed uniformly in the downgradient
direction, instead of being confined to the plume. More
importantly, the proposed exit levels were derived using a
carcinogenic risk target of 10-6, rather than 10-5, and the
90th percentile, rather than the 85th percentile, estimates
of risk were used. Using the 90th instead of 85th percentile
of the risk output results in estimating higher risks for a
given receptor for a given constituent concentration and in
more stringent (lower) exit levels. Thus, the proposed
HWIR-Waste risk calculations, especially for carcinogens,
are substantially more conservative in several important
respects than those used to derive the TC regulatory levels.
In the mineral processing risk assessment, DAF values were
derived for eight of the TC analyte metals. For waste piles,
the DAF values for the majority of the TC metals were
considerably higher than 100, the highest value being 1x1030
for lead. Barium, with a DAF value of 54, was the only metal
for which the mineral processing waste pile DAF was less
than the value of 100 used in the derivation of the TC
regulatory concentrations. These results imply that the DAF
value of 100 used in the TC derivation remains conservative
for most metals when compared to values derived for this
population of facilities.
The situation is different, however, if the DAF values
derived for mineral processing surface impoundments are used
as a basis for comparison. In this case, the majority of the
DAF values for the TC metals were less than 100. This
finding suggests that the DAF value of 100 used to derive
the TC regulatory levels may not provide adequate protection
against groundwater risks from surface impoundments, which
are the most frequent management type employed for
non-hazardous industrial wastes.
The large difference in DAF values for the two types of
management units can be explained partly in terms of the
comparative aridity of the locations for which DAFs were
calculated. Where little moisture was available to drive
transport from the waste piles through the vadose zone, DAF
values tended to be high. In contrast, the surface
impoundments provided a water supply that drove transport
through the vadose zone into groundwater. The extent to
which this effect would be seen in moister regions of the
country is not clear.
The HWIR-Waste proposed groundwater exit level calculations
for the TC analytes are summarized in Exhibit 3-5, and
compared to the TC regulatory levels. The majority of the
exit levels are considerably lower (more stringent) than the
corresponding TC regulatory levels. In 4 cases, the TC
levels are comparable to or less than the exit level. For 9
analytes, the ratio of the TC regulatory level to the exit
level is between 1 and 10. For 12 analytes, this ratio is
between 10 and 100; for 5 analytes, the ratio is between 100
and 1,000; and for 6 analytes, the ratio is greater than
1,000.
This distribution confirms that, generally, the assumptions
and modeling approaches used to derive the HWIR-Waste
proposed exit levels lead to somewhat more conservative or
more protective results than those used to derive the TC
regulatory levels. This conclusion holds true, even taking
into account that the cancer risk target is 10-fold lower
for setting  some of the proposed exit levels than was used
for setting the TC levels. For all but a few of the
carcinogens among the TC analytes, the proposed exit levels
are far more than 10 times lower than the corresponding TC
regulatory levels. Thus, some other factors account for a
significant proportion of the conservatism in these
calculations.
Some of this conservatism may be due to differences in
modeling assumptions, rather than modifications in modeling
techniques. For example:
!    The HWIR-Waste proposed exit levels were derived to be
protective of 90th percentile receptors, while the TC levels
were set to be protective of 85th percentile receptors.
!    As shown in Exhibit 3-5, some HWIR-Waste proposed exit
levels were driven by exposure pathways other than
groundwater.
!    The proposed HWIR-Waste exit levels and the TC
regulatory levels were designed for different purposes. The
TC levels are designed to provide a method for identifying
wastes that would otherwise be non-hazardous, while the
proposed HWIR-Waste exit levels would relieve wastes
previously identified as hazardous from stringent regulatory
control.
These issues are discussed in more detail in Sections 3.5.3
and 3.5.4. Other differences in modeling assumptions, such
as the retention of constituents in waste management (loss
terms) in TC modeling only and the differences in the
assumed location of wells relative to the contamination
source, influence the results in the other direction.
Summary. Based on the preceding analyses, only general
conclusions can be drawn about whether there are any
significant gaps in the TC associated with the specific
regulatory levels set for individual constituents. The wide
range in the mineral processing DAF values illustrates the
high degree of variability associated with specific
groundwater modeling assumptions, and does not necessarily
indicate whether the DAFs should be considered less or more
protective than when they were originally derived. The
HWIR-Waste proposed exit level calculations, on the other
hand, suggest that the application of more recent modeling
techniques might result in more conservative transport
calculations. Some, but not all, of this greater level of
protectiveness reflects a policy decision by the Agency
regarding what proportion of receptors should be protected
to the target risk level. In addition, advances in modeling
techniques and differences in specific input assumptions
also affect the differences in the apparent levels of
protectiveness.
3.5.3     Potential Inhalation Pathway Risks Associated with
TC Analytes
This section investigates the general level of
protectiveness of the allowable TC concentrations against
direct inhalation, a risk that the TC was not specifically
intended to protect against. EPA analyzed this issue by
performing screening-level risk calculations for long-term
air releases of the TC constituents from Subtitle D
facilities. EPA used the CHEMDAT8 model using facility
characteristic parameters for surface impoundments and land
application units (LAUs). Release estimates for all of the
organic TC analytes were developed for two scenarios.
!    In the first scenario, releases were estimated from the
same "high-end" surface impoundments and LAUs that were
modeled in the proposed HWIR-Waste exit level modeling.
!    The second scenario modeled releases from the "central
tendency" impoundments and LAUs, which were considerable
smaller and shallower than the high-end units.
In both release scenarios, the concentrations of the organic
TC analytes were assumed to be at the TC regulatory level
for liquid wastes in surface impoundments and at 20 times
the TC levels for nonwastewaters in land application units.
The latter assumption roughly estimates the maximum
concentration of the TC analyte that could be present
without the waste being hazardous, assuming efficient
leaching using the TCLP. For analytes that do not leach
well, this approach may underestimate exposure
concentrations and risks associated with air releases from
non-hazardous industrial wastes, since nonwastewaters with
high concentrations of constituents would not be identified
as hazardous by the TCLP. Average releases to air were
calculated for an assumed 40-year facility life-span under
both scenarios. The basic approach and input assumptions
used in the modeling are summarized in Exhibit 3-6.
The organic TC analytes for which releases were modeled vary
widely in molecular weight, vapor pressure, Henry's Law
constant, and other physical properties that affect releases
to air. Thus, the extent of release of these chemicals to
air from land disposal facilities might be expected to
differ widely. This is true to some extent; but, as can be
seen in Exhibit 3-7, the estimated release of these
compounds from land application units and surface
impoundments over the expected facility life-span varies
only moderately. In the case of the high-end land
application units, between approximately 7 percent and 100
percent of the chemicals entering the units are released to
the air over the facility life. The average proportion of
the analytes released from these units was 81.6 percent, and
the calculated releases were greater than 95 percent for
two-thirds of the organic TC analytes.
The results were similar for the central tendency LAU.
Releases ranged from 27 to 100 percent of the analytes, and
the average proportion released was 96.3 percent. The
explanation for the predicted higher proportional releases
from the central tendency LAU is not clear, but may be
related to the shallower tilling depth assumed for the
central tendency unit (0.2 compared to 0.3 meters).
The proportions of the TC analytes released from surface
impoundments are shown in the final two columns of Exhibit
3-7. The releases ranged from 6 to 77 percent of the applied
total per year for the high-end impoundment, with an average
release of 55.5 percent per year. Proportionate releases
were again higher from the central tendency unit, ranging
from 15 percent to 88 percent, with an average of 71.2
percent released annually. Similar to the situation for the
LAUs, the higher proportional releases from the central
tendency unit may be due to its considerably shallower depth
(2 meters) compared to the high-end unit (7 meters).
The limited impact of a chemical's Henry's Law constant on
air releases is somewhat surprising in light of the broad
spectrum of solubility and vapor pressure reflected in the
chemicals modeled. Perhaps it can best be understood as
indicating that, in the long run (a year or more), a high
proportion of any of these organic chemicals placed in
uncovered land management units will be released to the air,
provided other removal pathways are not important. In actual
practice, some land application units are covered to some
extent, and other removal processes, such as leaching,
biological and chemical degradation, and binding to soil or
sediment, compete to reduce air emissions significantly.
EPA calculated chronic risks from inhalation pathway
exposures for all organic TC analytes. To calculate exposure
concentrations, EPA multiplied release estimates by the
long-term fenceline dispersion coefficients used in the
proposed HWIR-Waste exit level calculations for the high-end
and central tendency surface impoundments and LAU releases.
The fenceline dispersion coefficients are used to represent
the nearest credible residential exposure locations, in
keeping with the proposed
HWIR-Waste risk methodology. Exposure durations are assumed
to be 30 years in the high-end exposure release and exposure
scenario, and 9 years in the central tendency scenario.
Exhibit 3-8 summarizes the results of the screening-level
risk estimation for the TC analytes having inhalation
pathway toxicity values in IRIS or HEAST (as discussed
below). The first eight columns of the results indicate
whether the estimated lifetime cancer risk associated with
managing the analytes at the TC (or the TC multiplied by 20)
concentrations in the various management units would be
greater than 10-5 or if the inhalation pathway hazard
quotient (HQ) would exceed 1.0. These risk threshold values
are the same as those used in developing the TC analyte
concentrations for groundwater exposures. For the 16 TC
analytes with IRIS Unit Risk values, inhalation pathway
cancer risks greater than 10-5 are not predicted for any of
the TC analytes released from the central tendency surface
impoundment. In contrast, cancer risks above 10-5 are
predicted for 12 of these analytes released from the
high-end impoundment. None of these analytes released from
the central tendency LAU would result in an inhalation
pathway risk greater than 10-5. Releases of four analytes
(chloroform, 1,4-dichlorobenzene, 1,1-dichloroethylene,
hexachlorobenzene, and toxaphene) from the high-end LAU
would result in risks above this level.
Of the four TC organics with inhalation RfCs, hazard
quotients greater than 1.0 were calculated for three
analytes (chlorobenzene, methyl ethyl ketone, and
nitrobenzene) released from the central tendency surface
impoundment. When releases are modeled from high-end
impoundments, the one additional chemical
(1,4-dichlorobenzene) also has an HQ greater than 1.0.
Exactly the same pattern is seen for LAUs.
These results indicate that, under assumptions of no
degradation or release to other pathways, the cancer risks
and non-cancer hazard indices associated with management of
some of the organic TC analytes may be above levels of
concern previously used in amending the TC.
These risks may be overestimated if significant amounts of
pollutants in waste are released through other pathways or
are degraded biologically or chemically. For this reason,
EPA used the proposed HWIR-Waste database to identify the TC
analytes that are persistent in soil or water. As shown in
the last two columns of Exhibit 3-8, most of the organic
analytes that exceed the air risk targets under the
assumption of no degradation are, in fact, not very
persistent in either soil or water. Using a cutoff value for
degradation rate constants of 0.5 year-1, which corresponds
to a half-life in soil or water of about 17 months, only 3
of the organic TC analytes are expected to be very
persistent. The relatively short half-lives in water or soil
may reduce the potential concern for inhalation pathway
risks associated with the other TC analytes to the same
extent. These results illustrate the need for more detailed,
site-specific modeling of all of the transport and
degradation processes.
Risks were calculated in this analysis for only those TC
analytes having inhalation pathway toxicity values
(Reference Concentrations or Unit Risk values) in IRIS. If
instead inhalation pathway toxicity values were derived for
the rest of the TC analytes from ingestion pathway values
and used in similar risk calculations, the number of
chemicals for which cancer risks and particularly non-cancer
risks would exceed levels of regulatory concern would be
much higher. These results have not been included in Exhibit
3-8 because EPA considers the level of uncertainty
associated with such procedures to be unacceptably high.
Evaluation of the proposed HWIR-Waste exit level
calculations for the TC analytes confirms the potential
concern for nongroundwater pathways. For some of the TC
analytes, the HWIR-Waste proposed exit level calculations
indicated that non-groundwater pathways are significant.
Findings include the following:
!    For 9 of the TC analytes, pathways other than human
groundwater exposure drove the establishment of proposed
exit levels.
!    For six of the analytes, ingestion of contaminated milk
or vegetables was the highest-risk exposure pathways.
!    For one of the pollutants, the driving non-groundwater
exposure pathway was direct inhalation.
!    For two analytes, ecological risks rather than health
risks drove the derivation of proposed exit levels.
In all of these cases, the initial release was to air
through volatilization. These indirect pathway risks will be
discussed in more detail in the following sections.
3.5.4     Potential Risks from Surface Water Exposures
This section investigates the general level of
protectiveness of the TC regulatory levels against surface
water exposures, a risk that the TC was not specifically
intended to address. Waste constituents could be released to
surface water from land management units through several
mechanisms:
!    Discharge of groundwater contaminated by leachate from
waste management units;
!    Transport of waste constituents to surface water bodies
by runoff and overland transport of wastes released from the
management unit;
!    Direct releases through overland runoff of liquid
wastes from surface impoundments; and
!    Volatilization of constituents from land-based units,
followed by deposition onto surface water or onto soil that
eventually finds its way into surface water bodies.
The surface water exposure pathways of potential
significance for humans include direct consumptive use
(i.e., ingestion and dermal contact with domestic water) and
dermal contact and incidental ingestion of the surface water
associated with recreational exposures. If the contaminants
are persistent in sediment, dermal contact and incidental
ingestion of small amounts of sediment also are possible
exposure pathways.
All of these release and exposure pathways have been
analyzed in the development of hazardous waste management
regulations and in other contexts. The experience gained in
these exercises has led the Agency to a number of general
conclusions regarding the importance of surface water
exposures for human health risks:
!    For common waste management practices, surface water
exposure cannot be automatically ruled out as insignificant
in comparison to groundwater, inhalation, and other indirect
pathways.
!    The significance of surface water releases depends
heavily on the management practices employed by a facility
and the specific interactions between surface water and
groundwater at the facility.
!    Generally, groundwater discharge significantly affects
surface water quality only where groundwater constitutes a
significant proportion of the total surface water in a water
body. This pathway may be important for very large
management units that generate large amounts of leachate,
but usually significant surface water quality impacts are
limited to relatively small streams adjacent to management
units and to on-site or adjacent ponds derived mainly from
leachate.
!    Exposure to volatile contaminants in surface water is
generally limited because these contaminants are depleted
rapidly from surface water through volatilization. Air
releases from surface water may themselves be significant
from a health standpoint. Usually, however, volatilization
from the management unit itself dominates, unless the unit
is covered.
!    Incidental ingestion and dermal contact with
contaminated sediment tend not to be significant exposure
pathways for humans, because of their infrequency and the
relatively small amounts of contaminated sediment contacted
(but see below).
!    Indirect pathway exposures may be of concern, however.
The contaminants that persist in sediment and have a high
capacity to bioaccumulate and bioconcentrate are often the
most significant contributors to human health risks. This
capacity may overcome the high dilution factors often
associated with releases to surface water. These persistent
pollutants most often reach human receptors through the
consumption of contaminated fish or shellfish.
In evaluating the potential risks associated with proposed
HWIR-Waste chemicals, EPA identified contaminants for which
surface water pathways were of potential concern. Whether or
not the surface water pathway was a concern depended on the
waste treatment scenario. For wastewaters managed in surface
impoundments, surface water was not a human health risk for
any of the TC analytes. All of the proposed exit levels
driving non-groundwater pathways for humans were associated
with volatilization followed by deposition on soil and did
not involve surface water. For nonwastewaters disposed in
land application units and waste piles, however, more than
50 percent of the proposed exit levels for the HWIR-Waste
constituents are driven by pathways involving surface water
exposures. The driving (highest-risk) pathways were
approximately equally divided among the contaminants between
overland runoff followed by fish uptake, and overland runoff
followed by surface water ingestion. These results must be
interpreted cautiously. The analysis of the proposed
HWIR-Waste exit levels cited above gives only a comparative,
not an absolute, indication of the importance of the surface
water exposure pathways for waste piles and land application
units. The proposed exit levels calculated for these types
of units are generally higher than those associated with
surface impoundments, for example, indicating that the
magnitude of the risks from wastes piles and land
application units are, in general, lower than those
associated with surface impoundments.
Summary. The preceding analysis has explored the possibility
that significant risks to health or the environment may be
associated with exposures through surface water pathways.
While a number of theoretical arguments suggest that such
releases might be important under only a relatively narrow
range of conditions, the proposed HWIR-waste modeling
results indicate that these pathways may well be significant
for some TC analytes disposed as non-hazardous industrial
wastes. The possibility that the surface water releases and
exposures represent a potential gap in the TC, especially
for persistent and bioaccumulative chemicals, cannot be
ruled out.
3.5.5     Potential Indirect Pathway Risks from TC Analytes
"Indirect" pathways are any pathways involving more than one
environmental medium (e.g., groundwater, air, surface water,
soil, sediment, and biota) between the release and the
exposed receptor. The initial release may be to any medium.
Indirect exposure pathways often, but not always, involve
uptake of environmental contaminants by living organisms,
which, in turn, are consumed by human or other receptors.
Some of the pathways discussed in the previous sections,
such as groundwater releases to surface water, are, strictly
speaking, indirect. This section, however, emphasizes
pathways involving potential long-range transport of
persistent pollutants and pathways involving biota (crops,
fish, or livestock) prior to human exposures.
Persistence, properties facilitating physical transport, and
the potential to bioaccumulate in the environment are
critical in the indirect pathways, and the physical/chemical
and environmental fate properties of constituents
significantly determine their movement through such
pathways. Exhibit 3-9 summarizes some important physical,
chemical, and environmental fate properties of the TC
analytes relating to persistence, partitioning behavior
between environmental media, and bioaccumulation. For each
parameter, the exhibit compares each constituent's value to
a criterion or cutoff value that roughly indicates whether
the parameter will strongly influence the transport and
partitioning of the chemical in the environment in a
multipathway analysis. The derivation of these criteria are
discussed in more detail in Section 4.3.2.
The first column identifies TC analytes with a high Koc
(high Kd for metals), generally indicating a propensity to
bind to soils. A high value means that chemicals will leach
only slowly to soil, but would bind to particulates if they
were released through runoff or into the air. Essentially
all of the chemicals with Koc values above 10,000 are
pesticides. In addition, the majority of the TC metals would
be expected to bind to some extent to particulates.
The next column on Exhibit 3-9 shows the Henry's Law
constants (kH) for the TC analytes, with values above 10-5
generally indicating a moderate to high capacity to
volatilize from soil-water systems, which may be the first
step in an indirect exposure pathway. About half (19) of the
TC analytes have kH values above 10-5. As discussed in
Section 3.5.3,  variations in Henry's Law constants did not
strongly effect the predicted long-term release of the TC
analytes from surface impoundments and waste piles.
Short-term releases, however, may be much more dependent on
this parameter.
The next two columns address the persistence of TC analytes
in soils, water, and air. Data in these two columns
summarize information from the proposed HWIR-Waste database
on the estimated half-life of chemicals in air and the
overall degradation rate constants in soils and surface
water. Four of the TC analytes are identified as having long
half-lives in air and 12 are persistent (have low
degradation rate constants) in soil and/or surface water.
The air half-life values must be interpreted cautiously, as
the proposed HWIR-Waste database contains this information
on only about 20 chemicals. Metals and many high-Koc
organics would also be expected to have long half-lives in
air if they were bound to particulates. As discussed
earlier, the TC analytes with long half-lives in soil/water
systems include primarily the metals and chlorinated
pesticides.
The final three columns of Exhibit 3-9 consider the
propensity of TC analytes to bioaccumulate in aquatic and
terrestrial ecosystems. The plant-soil bioconcentration
factor (BCF) is an estimate of the typical ratio of the
concentration of a constituent in soil to the concentration
in a particular kind of plant (in this case, forage plants
consumed by beef and dairy cattle). Similarly, the beef
biotransfer factor is an estimated typical ratio of the
concentrations of pollutants in the diet of beef cattle to
the resultant concentrations in edible tissue. Finally, the
BCF and bioaccumulation factor (BAF) values for fish
represent the typical ratios of pollutant concentrations in
surface water to that in fish tissue, considering only water
exposures or considering all pathways, respectively. (These
value tend to be quite similar for most chemicals.)
Although the exhibit indicates that several constituents may
bioaccumulate from soil to forage plants, in reality, only
2,4,5-trichloropropionic acid (Silvex) has a very high
bioconcentration potential. The value of the forage
biotransfer factor for this pesticide is five orders of
magnitude greater than for any other chemical (greater than
106). Generally the same chemicals have high beef
biotransfer factors, fish BCFs, and BAFs, with barium,
mercury, and lindane bioconcentrating only in aquatic
systems, and arsenic, chromium, selenium, and silver being
significant for the beef exposure pathways alone.
Summary. These single comparisons indicate the significant
potential for many TC analytes to be transported through
multiple media to reach the ultimate receptors. The data in
Exhibits 3-8 and 3-9 show that the chlorinated pesticides
(i.e., chlordane, endrin, heptachlor, heptachlor epoxide,
hexachlorobenzene, methoxychlor, pentachlorophenol, and
toxaphene), chloroform, and hexachloro-1,3-butadiene have
the potential to participate in indirect exposure pathways
and have non-groundwater pathways as their driving pathways.
In addition, several high-toxicity and persistent metals,
such as mercury, arsenic, and lead, also are of potential
concern.
3.5.6     Potential for Acute Adverse Effects of Exposures
to TC Analytes
The TC was originally established based on the need to
protect individuals from adverse health effects due to
chronic exposures to the TC constituents consumed in
groundwater. This approach to protecting against groundwater
exposure risks is conservative because the relatively long
time scale involved in groundwater transport to receptors,
under most reasonable assumptions, means that limiting
concentrations in any time period to the low chronic
risk-based levels also will protect against short-term
adverse effects. Short transient exposures to high levels of
groundwater contaminants are extremely uncommon. Before the
concentration of a pollutant reaches the relatively high
level required to cause acute effects, it generally will
have exceeded the allowable chronic exposure level for a
long period of time.
This relationship may not apply to exposure through pathways
not involving slow releases to groundwater. For example, the
rapid evaporation of volatile chemicals from a ruptured
container, the catastrophic release due to overtopping of a
surface impoundment, or runoff erosion from an extreme storm
event have the potential to result in short-term acute
exposures to humans and environmental receptors.
     For this reason, EPA has evaluated the potential level
of protectiveness of the TC against acute exposures. EPA
evaluated the potential for adverse effects associated with
acute volatilization of chemicals from land management
units. The approach was analogous to the screening-level
risk modeling for chronic exposure, except that the
short-term releases were calculated and exposure
concentrations were compared to short-term exposure
standards. This analysis indicates that the short-term
concentrations of all of the volatile TC analytes calculated
at the fenceline were far below applicable short-term
exposure standards (in this case, occupational exposure
standards).
This simple modeling does not unconditionally eliminate the
possibility of adverse effects from acute exposures to the
TC analytes. Unusual release events, such as fires, or
explosions, could result in higher exposures than calculated
assuming simple volatilization. In addition, high winds or
other events could result in high concentrations of
particle-bound metals and other non-volatile analytes. The
potential for these kinds of release events strongly depends
on specific waste characteristics, site conditions, and
management practices.
3.5.7     Potential Risks to Ecological Receptors from TC
Analytes
Risks to non-human receptors are the final category of risks
evaluated by EPA. Like the inhalation, surface water, and
indirect pathway risks, they were not expressly factored
into the derivation of the regulatory levels for the TC
analytes. While a substantial number of the TC chemicals are
toxic to ecological receptors, the protection of ecological
receptors was not a specific concern in the rulemaking. This
section discusses potential gaps in the TC characteristic
associated with harm to ecological receptors.
Many of the same factors that contribute to potential risks
for human receptors also contribute to potential risks for
ecological receptors. Generally, harm to environmental
receptors requires release of chemicals from containment and
transport to sensitive receptors without extensive
degradation or extreme dilution, just as in the case of
human health risks. Thus, the physical properties of
chemicals that contribute to persistence and transport in
the environment, as shown in Exhibit 3-9, are indicators of
potentially significant risks for ecological receptors. The
fact that most of the persistent chemicals with high
bioconcentration potentials are also pesticides, which are
toxic to certain plants, insects, or other animals, adds to
the potential risks.
The degree of protection of ecological receptors afforded by
the TC leachate concentrations does not appear very high for
many of the most toxic pesticides. Exhibit 3-10 compares the
TC regulatory levels to two basic measures of potential
aquatic toxicity, the acute and chronic Ambient Water
Quality Criteria (AWQC) for the protection of aquatic life.
It shows that, for many analytes, the allowable leachate
concentrations are many orders of magnitude above the
corresponding AWQC.
The shaded boxes in the table identify TC analytes with
regulatory levels greater than 1,000 times the AWQC. The
chemicals falling into this category again include the
chlorinated pesticides, chlorobenzene, lead, mercury,
silver, and 2,4,5-trichlorophenol. This ratio indicates that
if the TC analytes were released from wastes to groundwater
and from there discharged to surface water, a dilution of at
least 1,000-fold would be required to reduce the
concentration to levels not harmful to aquatic biota. Such a
scenario may be unlikely, however, because, as noted above,
these chemicals tend to bind strongly to soil and do not
move readily in groundwater. (As is discussed in more detail
in Chapter 2, however, some of these chemicals were found in
groundwater at concentrations above health-based levels in
the descriptions of environmental releases from
non-hazardous industrial waste management units.)
In a more likely scenario, the high ecotoxicity of these
chemicals means that runoff transport of particulate wastes
at concentrations not considered hazardous under the TC
could cause adverse effects in water bodies near management
units. As noted above, the concern for runoff exposures is
borne out to some extent by the proposed HWIR-Waste
modeling, where proposed exit levels are driven by this
pathway for disposal in waste piles and land application
units. In the case of silver and endrin (two of the
chemicals in shaded boxes in Exhibit 3-10), the proposed
exit levels were driven by runoff releases to surface water.
Summary. Based on these findings, it appears that the level
of protectiveness of the TC is not very high for some
non-human receptors. At a minimum, the ecotoxicity
parameters suggest a potential concern associated with the
aquatic toxicity of chlorinated pesticides, as well as a few
other chemicals. The severity of these potential gaps is
addressed in more detail in later chapters.
3.6 Potential Gaps Associated with TCLP
This section reviews the technical basis for the Toxicity
Characteristic Leaching Procedure (TCLP) and discusses
potential problems associated with its use based on a brief
review of available literature and data. Specifically, this
section focuses on whether the TCLP fails to accurately
predict releases from identified classes of wastes into
groundwater and non-groundwater pathways.
3.6.1     TCLP Background
In 1980, prior to development of the TCLP, the Agency
adopted the Extraction Procedure (EP) to identify wastes
likely to leach hazardous concentrations of particular toxic
constituents into the groundwater under conditions of
improper management. In 1986, the Agency proposed a modified
leaching procedure, the TCLP, to replace the EP. The Agency
promulgated the final rule on the application of the TCLP in
1990. In finalizing the TCLP, the Agency intended to improve
the leachate test procedure and eliminate some of the
analytical difficulties involved in the EP.
The TCLP is used to quantify the extractability of certain
hazardous constituents from solid waste under a defined set
of laboratory conditions. This test is used to evaluate the
leaching of TC metals, volatile and semivolatile organic
compounds, and pesticides from wastes. In principle, this
procedure simulates the leaching of constituents into
groundwater under conditions found in a municipal solid
waste (MSW) landfill. The TCLP, however, does not simulate
the release of contaminants to non-groundwater pathways. The
TCLP is most commonly used by EPA and state agencies to
evaluate the leaching potential of wastes, and for
determining toxicity. The TCLP is promulgated in Appendix II
of 40 CFR Part 261.24(a) and has been designated as EPA
Method 1311 in "Test Methods for Evaluating Solid Waste,
Physical/Chemical Methods - SW-846."
In the TCLP, liquid wastes (those containing less than 0.5
percent dry solid material) are "extracted" by filtering the
wastes through a 0.6 to 0.8 : glass fiber filter. Non-liquid
samples (those containing greater than or equal to 0.5
percent dry solid material) are:
!    Reduced to a particle size of less than 9.5 mm (liquid,
if any, is separated from the solid phase) and extracted
with an acetate buffer solution with either a pH of 5 or an
acetic acid solution with a pH of 3, depending on the
alkalinity of the waste (wastes with a pH of 5 and above are
extracted with the acetic acid solution);
!    A liquid-to-solid ratio of 20:1 is used for an
extraction period of 18 hours; and
!    The leachate is filtered and combined with the liquid
portion of the wastes, if necessary.
Contaminant analyses then are conducted on the extracts of
the liquids and non-liquids.
3.6.2     Limitations of the TCLP
The Agency reviewed TC constituent and concentration data
collected on releases from the non-hazardous industrial
waste management units discussed in Chapter 2 (see Exhibit
2-5). These data show that, of the 15 TC constituents
detected in at least three case studies, eight are present
in groundwater at levels much higher than their TC levels.
If the wastes passed the TCLP before being placed in the
management units, this could indicate that the TCLP
underestimated the long-term releases for certain classes of
wastes. One of the major limitations of these data, however,
is that they may not reflect current waste analysis or
management practices. For example, some data represent
releases from waste disposal that occurred prior to
implementation of the TCLP, and thus some of the releases
that exceed TC levels could be due to problems with other
extraction procedures or to the lack of any testing
procedure. Nevertheless, some site data (not reported in
Chapter 2) exists that may represent problems with the TCLP.
For example, the kiln residues from the treatment of spent
aluminum potliners at one facility are disposed in a
monofill as non-hazardous wastes. EPA approved a delisting
petition for the kiln residue waste based on TCLP data that
showed the target constituents in the TCLP extract to be
below treatment standards (which, for the TC constituents,
are lower than the TC regulatory levels). When the leachate
from the monofill was analyzed, however, levels of arsenic
were found to be higher than its TC level. Other hazardous
constituents, including cyanide and fluoride, were also
found at levels higher than those predicted by the TCLP.
Several technical and practical issues have been raised by
the regulated community and others regarding the
applicability of the TCLP for identifying hazardous waste. A
number of comments were submitted to the Agency in response
to the June 13, 1986 proposal to replace the EP with the
TCLP. The Agency responded to the comments in the final
rule, but also decided to continue to address commenters
concerns and further evaluate modifications to the TCLP. The
Agency stated that further improvements in the TCLP will be
proposed as they are developed. Subsequent to that
rulemaking, additional concerns have been raised by
commenters during later rulemakings (e.g., rules addressing
newly listed or identified wastes).
Some of the key issues regarding the TCLP identified from
these comments on various rulemakings and from other sources
are outlined below. TCLP underestimates leachate from some
high alkaline wastes or environments. The high alkalinity of
some wastes may make the TCLP an inappropriate predictor of
leachate composition. For example, the addition of acid
during the TCLP might not reduce the pH of high alkaline
waste to the same level as would occur over time in the
environment. Thus, long-term leachate concentrations of
constituents that are insoluble at higher pH ranges may be
underestimated in the TCLP leachate compared to the actual
leachate from the industrial landfills where a long-term
acid environment (e.g., from acidic rain water) is present.
Some toxic metal constituents are more mobile at both the
higher and the lower pH ranges. For example, studies show
that leaching of metals such as cadmium, chromium, and lead
typically is limited when the pH is in the range of about 8
or 9, but can increase significantly when the pH either
increases or decreases. Thus, if a waste is highly alkaline
(e.g., pH >11) and the TCLP acidic leaching medium lowers
the pH to only about 8 or 9, then the concentrations of
these metals in the TCLP leachate could be significantly
lower than would occur from either a highly alkaline or a
highly acidic environment (depending on a number of factors,
such as characteristics of any co-disposed wastes, type of
treatment, and characteristics of the soil and rain water).
Several commenters to the June 13, 1986 TCLP proposal
expressed concern regarding the application of the TCLP to
alkaline wastes. They noted that no high alkaline wastes
were included in the development of the TCLP and, therefore,
no conclusions could be made concerning the actual behavior
of these wastes. The MEP, described in the text box, is one
test that the Agency and others use that may better simulate
the long-term leaching behavior of such wastes.
TCLP underestimates the leachate concentrations from oily
wastes and some paint wastes. Several reports indicate that
oily and some paint wastes tend to clog the filters used to
separate the extract from the solids prior to analysis,
resulting in under-reporting of the extractable constituent
concentrations. Several commenters on the June 13, 1986 TCLP
proposal noted that, in the development of the TCLP, the
Agency tested only 11 wastes. These commenters argued that
increasing the variety of wastes  (to include oily wastes,
organic chemical wastes, and municipal wastes) and the
number of extractions performed could refine the TCLP and
enhance its accuracy.
TCLP may not accurately mimic conditions commonly found in
non-hazardous industrial waste disposal. As discussed in the
1980 final EP rule, several commenters responding to the
proposed use of the EP for evaluating the leaching of
hazardous constituents argued that the co-disposal
assumption is not applicable to wastes that are never
co-disposed with municipal solid wastes and thus do not
leach at the aggressive rates characteristic of co-disposal
situations. Thus, the commenters stated, the leachate
procedure does not simulate the conditions found in
industrial waste monofills. In response, the Agency stated
that most wastes, even those that are unlikely to be
disposed in a municipal landfill, are likely to come into
contact with some form of acidic leaching medium during
their management histories or could otherwise encounter
environments that could cause the wastes to leach comparable
levels of toxic constituents.
This same debate occurred during development of the TCLP,
and it continues today. For example, the Lead Industries
Association Inc., commenting on the Phase IV supplemental
proposed rule, cited an EPA study that stated that acetic
acid leaching fluid could selectively solubilize toxicants
(specifically lead) and incorrectly classify the material as
hazardous when, in fact, no mobilization (leaching) would be
expected to occur in the landfill environment. Kennecott
Corporation and National Mining Association, also in
response to the Phase IV supplemental proposed rule, stated
similar concerns. The SPLP (see text box at right) is one
test that has been considered for addressing this issue.
TCLP may underestimate the chelation-facilitated mobility of
some waste constituents. A recent analysis of the TCLP and
Cal WET (see text box at right) indicates that the low
chelation activity of the acetate buffer used in the TCLP
may underestimate the ability of leachate containing
chelating agents to mobilize waste constituents. Cal WET
uses a citrate buffer that approximates the chelation
ability of many other compounds of landfill leachate and,
thus, overcomes the constraints of the TCLP test.
TCLP does not account for the oxidation/reduction reactions
occurring in landfills. A recent study noted that the
addition of iron filings to stabilize foundry sand wastes
seems to mask the potential leachability of lead by
interfering with the TCLP. If metallic iron (iron filings)
are added to the waste, the lead concentration in the TCLP
extract may be decreased by an oxidation/reduction reaction
to levels below the lead TC level. If, however, the waste is
placed in a landfill or surface impoundment, the iron
oxidizes over time and loses its ability to further reduce
the lead ions. This results in the leaching of lead to the
environment.
Another recent study reviewed the practice of using iron as
an additive in stabilizing paint waste. The study notes that
the iron reduces the lead ions in paint waste to the less
soluble metallic lead, which is subsequently removed by
filtration from the leachate being analyzed. This use of
iron allows the lead-containing waste to pass the TCLP. The
study notes, however, that repeated leaching of the same
waste sample increases the leaching rate to a point where
lead is sufficiently solubilized to exceed the TC regulatory
level.
Finally, another study showed that oxidation/reduction
potential has a significant effect on leaching of metals
from stabilized waste materials. This study showed that the
leaching of chromium increases significantly under highly
oxidizing conditions, and the leaching of arsenic, vanadium,
lead, and iron increase significantly under reducing
conditions.
TCLP may not predict long-term mobility of organic
contaminants in some treated wastes. A fairly recent
Superfund Innovative Technology Evaluation (SITE) field
evaluation examined the long-term performance of
stabilization treatment of lead and other metals, oil and
grease, and mixed volatile and semivolatile organic
compounds. Portland cement and a proprietary additive were
used as stabilizing agents. Durability was tested with
weathering tests by wet-dry and freeze-thaw cycling and by
sampling stabilized treated waste after 9 and 18 months of
burial. The results showed that organic contaminants were
not effectively immobilized (although the testing also
showed that lead and other metals remained highly
immobilized, the physical properties of the stabilized
treated waste deteriorated only slightly, and the porosity
decreased).
Another study conducted on the long-term leaching
performance of commercially stabilized waste demonstrated a
highly waste-dependent effect of time on the TCLP results.
In this study, TCLP extraction was performed on both the raw
waste and the treated waste. The treated waste consisted of
samples at 28, 90, 200, 470, and 650 days after treatment.
The results showed that leachate values for some metallic
wastes increased over time.
TCLP may not be appropriate for some contaminated soil. The
Michigan Department of Natural Resources (MDNR) believes
that the TCLP is not appropriate for soils contaminated with
cyanides, sulfides, and hexavalent chromium. Furthermore,
MDNR reports that the SPLP (see previous text box) more
accurately simulates the conditions of contaminated soil and
therefore is an appropriate alternative test for soil
contaminated with cyanides, sulfides, and hexavalent
chromium.
TCLP does not predict releases to non-groundwater pathways.
As discussed in Section 3.4, the TCLP was designed to
simulate the leaching of waste constituents to groundwater
and not for releases to non-groundwater pathways. The TCLP
does not simulate the release of volatile organic
contaminants into air either directly or through entrained
dust, nor does it simulate releases through surface runoff.
CHAPTER 3. POTENTIAL GAPS ASSOCIATED WITH HAZARDOUS WASTE
           CHARACTERISTICS DEFINITIONS . . . .3-1
3.1  Types of Risks Addressed by RCRA Hazardous Waste
     Characteristics   3-1
3.1.1     Statutory and Regulatory Framework. . . . . .3-1
3.1.2     Risks Associated with Physical Hazards. . . .3-3
3.1.3     Acute Toxic Hazards to Humans . . . . . . . .3-4
3.1.4     Chronic Toxicity Risks to Humans. . . . . . .3-4
3.1.5     Risks to Non-Human Receptors. . . . . . . . .3-5
3.1.6     Other Risks Associated with Non-Hazardous
          Industrial Waste Management                  3-6
3.2  Ignitability Characteristic . . . . . . . . . . . 3-8
3.2.1     Definition of Ignitability. . . . . . . . . .3-8
3.2.2     Potential Gaps Related to Definition of
          Ignitability                                 3-9
3.2.3  Potential Gaps Related to Ignitability Test
       Methods                                         3-12
3.3  Corrosivity . . . . . . . . . . . . . . . . . . . 3-12
3.3.1     Definition of Corrosivity . . . . . . . . .  3-12
3.3.2     Potential Gaps Related to Definition of
          Corrosivity                                  3-13
3.3.3     Potential Gaps Related to Corrosivity Test
          Methods                                      3-16
3.4  Reactivity. . . . . . . . . . . . . . . . . . . . 3-16
3.4.1     Definition of Reactivity. . . . . . . . . . 3-16
3.4.2     Potential Gaps Related to Definition of
          Reactivity                                  3-17
3.4.3     Potential Gaps Related to Reactivity Test
          Methods                                     3-19
3.5  Potential Gaps Associated with the Toxicity
     Characteristic                                   3-19
3.5.1     Definition of Toxicity Characteristic . . . 3-19
3.5.2     Changes in Groundwater Pathway Analysis . . 3-21
3.5.3     Potential Inhalation Pathway Risks Associated
          with TC Analytes                            3-27
3.5.4     Potential Risks from Surface Water Exposures3-33
3.5.5     Potential Indirect Pathway Risks from TC
          Analytes                                    3-35
3.5.6     Potential for Acute Adverse Effects of Exposures
          to TC Analytes                              3-38
3.5.7     Potential Risks to Ecological Receptors from TC
          Analytes                                    3-38
3.6  Potential Gaps Associated with TCLP . . . . . . .3-39
3.6.1     TCLP Background . . . . . . . . . . . . . . 3-39
3.6.2     Limitations of the TCLP . . . . . . . . . . 3-42
Exhibit 3-1. Risks Potentially Associated with Non-Hazardous
             Industrial Waste Management    3-7
Exhibit 3-2  Materials Formerly Classified by DOT as
             Combustible Liquids (which generally are not
             RCRA ignitable). . . . 3-11
Exhibit 3-3  Other Definitions of Reactivity . . . .3-18
Exhibit 3-4  TC Constituents and Regulatory Levels (mg/l)
                                   3-20
Exhibit 3-5  Comparison of TC Regulatory Concentrations
             and HWIR-Waste Proposed Exit/Leach Levels 3-25
Exhibit 3-6  Summary of Inhalation Pathway Screening
             Methods, Input Data, and Models Used for
             Bounding Risk Analysis 3-29
Exhibit 3-7  Emission Fraction for Air Releases of Volatile
             TC Analytes        3-30
Exhibit 3-9  Major Fate and Transport Parameters for TC
             Analytes . 3-36
Exhibit 3-10 Ratios of TC Leachate Regulatory Levels to
             Ambient Water Quality Criteria for Aquatic
             Life . . 3-40
CHAPTER 4. POTENTIAL GAPS ASSOCIATED WITH NON-TC CHEMICALS
This chapter identifies potential gaps in the hazardous
waste characteristics associated with chemicals not on the
toxicity characteristic list. Chemicals and chemical classes
are identified as potential gaps based on their hazardous
properties such as toxicity to humans and ecological
receptors, their fate and transport properties such as
persistence and bioconcentration potential, and their
potential for occurrence in non-hazardous industrial wastes.
This approach to identifying gaps is complemented by the
approach discussed in Chapter 5, which identifies gaps in
terms of the important environmental risks and their
potential association with waste management, rather than
focusing on specific chemicals.
4.1  Overview of Methodology
EPA identified potential gaps in the characteristics
associated with non-TC chemicals through a six-step process,
as shown in Exhibit 4-1. Each of these steps is described
below.
Step 1:  Identify and Classify Known Non-Hazardous
Industrial Waste Constituents
An essential task in this analysis is identifying a universe
of chemicals that are either known or likely to be present
in non-hazardous industrial wastes, excluding TC analytes
(which are addressed in Chapter 3). In the analysis that
follows, these two classes of chemicals are referred to as
known non-hazardous industrial waste constituents and
possible non-hazardous industrial waste constituents,
respectively. As described in Section 4.2, the
identification of the "known" non-hazardous constituents is
relatively straightforward, although reliable data on the
composition of non-hazardous industrial waste are limited.
The data sources used to identify these constituents are
shown in the top panels of Exhibit 4-1. They are the
non-hazardous industrial waste release descriptions
(discussed in Chapter 2), the Industrial Studies Data Base
(ISDB), Effluent Guidelines Development Documents, and
Listing Documents from recent rulemakings for dyes and
pigments and solvent wastes. As discussed in Section 4.2,
the distinguishing characteristic that makes a chemical a
"known" non-hazardous industrial waste constituent is that
it has been documented through direct chemical analysis to
occur either in non-hazardous industrial waste or in
environmental media contaminated by releases from
non-hazardous industrial waste management units.
Step 2:  Identify and Screen Possible Non-Hazardous
Industrial Waste Constituents
In addition to the chemicals that are known to be present in
non-hazardous industrial wastes, EPA identified other
chemicals that have a high likelihood of being present in
such wastes and could pose significant risks to human health
or the environment. Unlike the known non-hazardous
industrial waste constituents, however, the possible waste
constituents have not been confirmed as non-hazardous
industrial waste constituents through direct chemical
analysis in any of the data sources used by the Agency. To
identify non-hazardous industrial waste constituents that
could pose risks to human health or ecological receptors,
the Agency reviewed 36 lists of chemicals created for
regulatory and advisory purposes by EPA, other federal
agencies, states, other countries, and advisory and
scientific bodies. These lists were originally created based
on criteria such as toxicity, fate and transport
characteristics, production volume, widespread use, and
detection in environmental media.
Rather than include all the chemicals on these lists as
possible non-hazardous industrial waste constituents, EPA
narrowed the list of chemicals to those most likely to pose
significant risks to human health and the environment. The
screening was performed in two steps, as shown in the upper
right-hand panels of Exhibit 4-1. First, chemicals were
screened with regard to individual toxicity and fate and
transport properties. Then, the resulting high-hazard
chemicals were screened against 1994 national Toxic Release
Inventory (TRI) release data, serving as a proxy for
potential occurrence in waste. Section 4.3 describes the
process of compiling and screening possible non-hazardous
industrial waste constituents.
Step 3:  Apply Hazard-Based Screening Criteria
In this step, which is described in detail in Section 4.4,
EPA compared the lists of known and possible non-hazardous
industrial waste constituents and screened them against
single and multiple hazard-based screening criteria. In Step
2, individual chemicals that are possible non-hazardous
industrial waste constituents were screened on the basis of
single indicators of hazard (e.g., a low reference dose or a
high bioconcentration factor). This step refines this
analysis by examining both the known and possible
non-hazardous industrial waste constituents against single
and multiple indicators of toxicity, fate, transport, and
occurrence in waste, and by reviewing the implications of
this screening for classes of chemicals.
Step 4:  Review Relevant Multipathway Risk Modeling Results
Section 4.5 reviews the results of the multipathway risk
modeling conducted as part of the proposed HWIR-Waste
(Hazardous Waste Identification Rule for Process Wastes)
determination of exit levels, where available for chemicals
on the combined list of known or possible non-hazardous
industrial waste constituents. The proposed exit levels and
risk-driving pathways provide information on the relative
risks posed by the various constituents and on the most
important exposure pathways.
Step 5:  Identify Potential Acute Hazards
In the prior steps, the evaluation of potential hazards
associated with the possible and known non-hazardous
industrial waste constituents has focused on chronic toxic
effects. In Section 4.6, the possible and known constituents
are compared to acutely hazardous chemical lists developed
by EPA and other regulatory agencies. This analysis thus
addresses risks from acute exposures and from physical
hazards associated with reactivity, flammability, and
corrosivity.
Step 6:  Summarize Findings
Chapter 4 concludes by identifying non-TC chemicals and
groups of chemicals that constitute potential gaps in the
hazardous waste characteristics. Section 4.7 presents a
table identifying these potential gaps, the rationale for
their identification, and the major issues and data gaps
remaining to be resolved to judge the severity of these
potential gaps.
4.2  Identify and Classify Known Constituents of
Non-Hazardous Industrial Wastes
Chemicals present in non-hazardous wastes that have been
released from non-hazardous industrial waste management
units into the environment may constitute potential gaps in
the hazardous waste characteristics. This section reviews
the available evidence concerning such chemicals. Reliable
data concerning the chemical composition of non-hazardous
industrial wastes, however, are quite limited for two major
reasons. First, such wastes may be generated by virtually
any industrial facility or operation and are inherently
heterogeneous. Second, state requirements to analyze
non-hazardous industrial wastes and to report analytical
results are quite limited.
In the course of this Scoping Study, the Agency identified
four sources of information regarding the composition of
non-hazardous industrial wastes:
!    The descriptions of environmental releases from
non-hazardous industrial waste management facilities,
compiled as part of this Scoping Study, which were
summarized in Chapter 2;
The Industrial Studies Data Base (ISDB), which includes
information on point of generation constituent
concentrations on various industries;
!    Chemicals identified as being present in liquid
non-hazardous wastes by EPA Effluent Guideline Development
Documents, as summarized in the Capacity Analysis for the
Phase III Land Disposal Restrictions (LDR) Rule; and
!    Chemicals identified as being present in non-hazardous
industrial waste that were not listed as hazardous wastes in
background documents for recent Agency listing/no-listing
proposals for pigments and dyes industries and for solvents.
The first source provides information on chemicals detected
in environmental media (primarily groundwater) that were
released from non-hazardous industrial waste management
facilities, while the other three sources provide
information on the composition of non-hazardous industrial
wastes. Although not reflected in this Study, in future
investigations the Agency will consider examining the
constituents present in remediation waste from non-hazardous
industrial waste management units.
The descriptions of environmental releases in Chapter 2
identify the constituents found in environmental media near
non-hazardous industrial waste management units, their
maximum detected concentrations, the types of units from
which the releases occurred, and the industries responsible
for the releases. The release descriptions provide direct
evidence of potential environmental exposure to
non-hazardous industrial waste constituents and damage to
human health and the environment. They, however, do not
encompass all instances where non-hazardous industrial waste
management has resulted in releases to the environment or
other potential risks. As noted in Chapter 2, the release
descriptions come from only a small proportion of the
states. However, they do represent a large proportion of the
readily identifiable releases from facilities regulated by
state non-hazardous industrial waste programs.
In addition, some types of occurrences (e.g., fires and
explosions) and units (e.g., waste piles) are generally not
regulated by these state programs, and would not show up in
the records EPA examined. The quantitative data from these
descriptions generally were limited to groundwater
monitoring results. Few releases to other media were
identified. In addition, the chemicals identified tend to be
those whose monitoring is required under existing regulatory
programs. The potential for identifying chemicals not
already recognized as hazardous is therefore limited.
Finally, the data sources evaluated did not provide useful
information on various types of uses constituting disposal,
such as cement additives, soil amendments, or aggregate.
The ISDB was the second source of data used to identify
known waste constituents. EPA has maintained this data set
since 1982. It contains information on point-of-generation
constituent concentrations for 16 industries. The sources of
information include RCRA Section 3007 questionnaires, plant
visit reports, sampling and analysis reports, and
engineering analysis. Its major limitations include data
that are sometimes more than 15 years old and the coverage
of only selected industries.
The third data source was information gathered by EPA's
Office of Water in preparing Effluent Guidelines Development
Documents. These data are summarized in OSW's Capacity
Analysis Background Document for the Phase III LDR. The data
describe the composition of non-hazardous industrial
wastewaters generated by major industry groups. These
wastewater data are of varying age, and therefore their
continued representativeness is unclear. Also, the number of
analytes in the database is quite limited. As seen below, a
very high proportion of the waste constituents identified in
this source also are identified in one or both of the two
data sources described above. Thus, the effluent guidelines
data serve mainly to confirm data from the other sources.
The Agency also reviewed two recent proposed listing
decisions for hazardous wastes, those for solvent wastes and
for wastes from the dyes and pigments industries. Several
additional chemicals were identified as being constituents
of unlisted (non-hazardous) solvent waste streams that were
not found in any of the other data sources:
2-methoxyethanol, 2-ethoxyethanol acetate, cyclohexanol,
isophorone, and diethylamine. No non-hazardous industrial
waste constituents from the dyes and pigments industry were
identified, because all of the data concerning the
compositions and generation rates of these wastes were held
as confidential by the industries that submitted data.
Excluding TC analytes, which are addressed in Chapter 3, a
total of 146 chemicals were identified in the release
descriptions, 183 in the ISDB, and 19 in the effluent
guidelines data. An additional five unique constituents were
found in the listings background document. Overall, a total
of 250 unique chemicals were identified.
The chemicals and waste constituents identified in the three
data sources are sorted into major chemical classes and
shown in Exhibit 4-2. These constituents span a wide range
of chemical classes. Even with a number of possibly
redundant entries, the most common category of chemicals was
metals and inorganics, with 48 chemicals. Other prominent
families of chemicals included volatile chlorinated organics
(38), other semivolatile organics (46), other volatile
organics (45), and pesticides and related compounds (29).
Included among the chlorinated organics are several
trihalomethanes and two chlorofluorocarbons. The "other
semivolatile" category contains a wide range of compounds,
many of which are found only in the ISDB data. The
pesticides category contains mostly chlorinated organic
pesticides and intermediates, but also contains some
nonchlorinated compounds.
Less prominent categories of chemicals include the PAHs (18
compounds), volatile hydrocarbons (12), phenolic compounds
(8), and phthalate esters (6). The PAHs range from
low-molecular weight, noncarcinogenic compounds (such as
naphthalene) to the higher molecular weight carcinogens and
mutagens (such as benzo(a)pyrene). All but one of the
volatile hydrocarbons (styrene) are commonly found as
constituents in kerosene, gasoline, and related fuels.
Styrene is a monomer used in plastics production. The
phenolic compounds include creosote components (cresols) and
two nitrophenols. Most of the phthalate esters are found in
all the first three data sources, including the suspect
carcinogen bis-(2-ethylhexyl)-phthalate. Polychlorinated
biphenyls (PCBs) and chlorinated dioxins (represented by
2,3,7,8-TCDD) were found in the ISDB.
The number of compounds in the various categories does not
necessarily reflect the relative potential importance of the
chemicals or categories. As noted above, some chemicals
occur only in one database, while others occur in two,
three, or all four. In addition, some chemicals occur in
more than one release description, that is, at more than one
facility, or are identified as waste constituents from more
than one industry group. Except for the chemicals in the
release descriptions, there is no indication of the relative
concentrations of the chemicals in wastes.
Given the wide range of chemical classes represented in the
lists, and the relatively small total number of non-TC
chemicals in the four datasets (250), the Agency found no
convincing reason to eliminate any candidate chemicals from
inclusion in the gaps analysis. Given that toxicological and
fate and transport data are available for most of these
chemicals, all the chemicals were carried forward for
further analysis.
4.3  Identify Possible Non-Hazardous Industrial Waste
Constituents of Potential Concern
This section describes the approach to identifying
additional chemicals that might constitute potential gaps in
the hazardous waste characteristics. Unlike the previous
analysis, which began with four relatively narrow and
specific data sources, this analysis begins with a wide
range of data sources, in order to avoid excluding chemicals
of potential concern. Subsequently, a substantial proportion
of the large universe of chemicals are screened out on the
basis of toxicity, fate and transport characteristics, and
potential for occurrence in waste. A large portion also
could not be evaluated because of a lack of data. The result
is a focused list of possible non-hazardous industrial waste
constituents that could pose significant risks to human
health or the environment. The list of possible
non-hazardous industrial waste constituents supplements the
list of known non-hazardous industrial waste constituents
developed in the previous section.
4.3.1     Approach to Identifying Potentially Hazardous
Chemicals
Excluding TC analytes, EPA identified over 2,300 distinct
chemicals from 36 regulatory and advisory lists originally
created by EPA, other federal agencies, state and national
regulatory agencies, and special environmental task forces
and advisory bodies. Exhibit 4-3 identifies these lists. The
RCRA regulatory lists included are the 40 CFR 261 Appendix
VII and VIII lists of hazardous waste constituents, the
proposed HWIR-Waste Chemicals, and the HWIR-Media "Bright
Line" chemicals. Other major federal regulatory lists
include the Clean Water Act Section 307 Toxic Pollutants and
Section 311(b)(2) Hazardous Substances, the CERCLA list of
hazardous substances with reportable quantities, the
Emergency Planning and Community Right-to-Know (EPCRA) Toxic
Chemicals and Extremely Hazardous Substances lists, the
Clean Air Act Amendments Section 112(b) Hazardous Air
Pollutants and Section 112(r) Regulated Toxic Substances,
and chemicals for which OSHA has published Permissible
Exposure Limits (PELs). The U.S. Department of
Transportation (DOT)Hazardous Materials Transportation Act
(HMTA) Hazardous Materials Registry (HMR) also was used to
identify potential gap chemicals, but could not be directly
included in the database in time because of format
differences in the available machine-readable forms of the
list.
Some of the advisory lists that were included are the 1992
EPA Hazardous Substance Task Force's Level 1 and Level 2
hazardous chemicals that were identified as not being
controlled under RCRA or DOT regulations, the Focus
Chemicals for the Great Waters Study, chemicals identified
by Environment Canada under the ARET Toxics Scoring
Protocols, chemicals identified by the University of
Tennessee Chemical Ranking System, and the Michigan Critical
Materials Register. Some lists address specific types of
hazards, such as potential endocrine disruptors, acutely
toxic chemicals, highly flammable chemicals, and highly
reactive chemicals. Brief descriptions of the lists and the
selection criteria that were applied to derive them are
provided in "Background Document:  Identification of
Chemicals from Regulatory and Advisory Lists Representing
Potential Gaps in the Hazardous Waste Characteristics."
Naturally, there is a high degree of overlap among the
chemical lists. Some lists are subsets of, combinations of,
or otherwise derived from other lists. Nonetheless, the
chemicals identified represent a very broad spectrum of
potential hazards. High-volume and highly toxic chemicals
appear on many lists, as do acutely toxic, flammable, and
reactive chemicals. Several lists specifically seek to
include carcinogens, mutagens, and teratogens. Some lists
are derived based on considerations of ecotoxicity,
persistence, and bioaccumulation potential, or based on
specific environmental media or geographical concerns. The
overall goal in the Scoping Study was to identify the
broadest possible set of chemicals of potential concern, and
then to screen them down to the chemicals with the highest
potential to pose risks to human health or the environment.
4.3.2     Screening Approach
EPA performed the hazard-based screening of potentially
hazardous constituents in two steps. First, the entire list
of chemicals was screened against criteria related to
toxicity to humans and aquatic organisms and separately
against various fate and transport criteria. Chemicals for
which data were not available for at least one of these
criteria were not included in further analysis. In the
second step, EPA took all of the chemicals identified as
either highly toxic, mobile, persistent, or bioaccumulative
and first screened them against the proxy for occurrence in
waste, namely the TRI release data. Any chemical passing
this screen has a high potential for occurrence in waste and
was identified as a possible non-hazardous industrial waste
constituent. Chemicals were also retained in the analysis if
they were not on the TRI list. Only the chemicals confirmed
as having low releases through the TRI data were eliminated
from being possible constituents.
The criteria considered for use in screening (both the
possible constituents described in this section and the
combined lists discussed in Section 4.4) are summarized in
Exhibit 4-4.
     These criteria were derived using professional judgment
to provide a reasonable level of discrimination between
chemicals with relatively high-hazard potential and those
with lower potential. For most toxicity parameters, which
were available only for a relatively small number of more
toxic chemicals, the cutoff values were set at the 50th
percentile of the entire range of values. For many fate and
transport parameters, the criteria were set at or around the
75th percentile (or 25th percentile, if a low value implied
high hazard potential) of the entire range of the parameter
values for all of the chemicals for which the parameter was
available. In some cases, the screening criteria were set at
levels generally recognized as indicative of hazard
potential.
In the course of the Scoping Study, many different criteria
for and approaches to the screening process were evaluated;
the background document to this Study provides further
detail. The criteria and approach described in this section
is a relatively simple one that evolved from those previous
efforts. One of the major lessons learned in that work was
that screening is inherently imprecise, and no single screen
will catch or exclude all the chemicals desired. Another
lesson learned is that screening large lists against complex
criteria can quickly become very complicated, and the return
on the complexity, in terms of useful information, can be
quite low. Therefore, EPA has focused on a relatively small
number of criteria that are important in determining risk
potential and has critically interpreted the results of the
screening.
In the case of carcinogens, two sets of criteria were used.
The first set indicates whether a cancer slope factor (CSF)
had been promulgated for the chemical. The second indicates
whether an inhalation unit risk (UR) had been developed.
These criteria identified the bulk of human carcinogens. For
noncarcinogenic effects, two sets of criteria again were
used. The first indicates whether an ingestion reference
dose (RfD) had been developed at a sufficiently toxic level
for the purposes of this analysis (i.e., below the 50th
percentile). The second indicates whether an inhalation
Reference Concentration (RfC) had been developed below the
50th percentile. For aquatic effects, the 50th percentile of
the Chronic Ambient Water Quality Criteria (AWQC) was used.
EPA used several criteria to screen fate and transport
properties. The screening criteria for the fish
bioconcentration factor (BCF) and bioaccumulation factor
(BAF) were both set at 1,000 l/kg, the beef biotransfer
factor was set at 7.8x10-3 day/kg, and the octanol-water
partition coefficient (Kow) was set at 105. These four
values indicate the potential for the chemicals to be taken
up and/or accumulated by organisms. The vapor pressure
criterion, used as a proxy for volatilization release, was
set at 1 mm Hg. A Henry's Law constant (kH) value of 10-5
atm-m3/mole was also used to identify chemicals with high
volatilization potential. The criterion used to identify
persistent chemicals in soil or water (degradation rate
constant less than 0.5/year) was selected based on an
analysis of the EPACMTP findings for organic pollutant
transport in groundwater, which indicated that, at rate
constants above this value, the calculated DAF values begin
to differ substantially from those for non-degrading
pollutants with similar properties.
     As noted in Section 3.5, the screening-level risk
analysis also was used to identify screening criteria and
their importance. For example, Henry's Law constants were
found not to be a good indicator of the potential for
long-term volatilization releases, so that the parameter is
not used as a primary screening factor (although it is
examined briefly in the next section). Instead, vapor
pressure is used to screen chemicals for volatilization
release. Even this screen must be interpreted cautiously,
however, since chemicals with low vapor pressures can still
volatilize from treatment units if no other processes are
occurring to limit the releases.
The primary data source that is used as a proxy for
occurrence of hazardous chemicals in non-hazardous
industrial wastes is the release data, reported under the
Emergency Planning and Community Right-to-Know Act (EPCRA)
Toxic Release Inventory (TRI) requirements. For purposes of
the screening conducted for this study, EPA considered those
chemicals with releases to air, land, water, and underground
injection exceeding one million pounds in 1994. Under EPCRA
Section 313, facilities with more than 10 full-time
employees that are classified in SIC codes 20 through 39
(i.e., manufacturing) must submit reports if they
manufacture or process more than 25,000 pounds of a TRI
chemical or otherwise use more than 10,000 pounds of a TRI
chemical in a given calendar year. There were a total of 73
unique chemicals and 10 classes of chemicals in this
category, out of the 345 individual chemicals for which
reports are required. These chemicals account for greater
than 99.8 percent of the total TRI releases of all
chemicals. As discussed in Section 4.4.2, the combined list
of known and possible non-hazardous industrial waste
constituents were also screened against non-CBI 1994
production data from the TSCA Inventory.
A major limitation of this screening approach is that
quantitative toxicity and fate and transport parameter
values were available for only a fraction of the over 2,300
non-TC chemicals identified. Human toxicity parameters were
available for just over 430 chemicals, ambient water quality
data for 105 chemicals, and complete fate and transport data
for 194 chemicals. For this reason, the screening approaches
were supplemented by searching lists that identify chemicals
presenting specific types of hazards, even if no
quantitative parameter value was available, and by applying
professional judgment to identify where potential risk
findings for individual chemicals may be generalized to
broader classes of chemicals. The results of this screening
are described in a background report (see footnote 6).
4.3.3     Toxicity, Fate, and Transport Screening for
Possible Non-Hazardous Industrial Waste Constituents
Exhibit 4-5 summarizes the results of the screening for
possible non-hazardous industrial waste chemicals against
the toxicity criteria. The first two columns indicate the
chemicals that are suspect or known human carcinogens having
ingestion CSFs or inhalation URs.
     The last three columns identify the chemicals with oral
RfDs, inhalation RfCs, and AWQCs below the 50th percentile
of these parameter values (a low value indicates high
toxicity) for all chemicals for which these values have been
developed. Note that this table does not include TC analytes
or chemicals previously identified as known non-hazardous
industrial waste constituents.
As noted previously, the number of chemicals identified on
all 37 lists of chemicals is much greater than the numbers
of chemicals for which toxicity parameters have been
developed. Furthermore, the list of chemicals, which
includes practically all of the known chemicals from Section
4.2 and all of the TC analytes, includes almost all
chemicals for which these toxicity values have been derived.
Thus, the toxicological screen has the potential to screen
out most of the possible non-hazardous industrial waste
constituents simply because most of the constituents do not
have toxicity values, and therefore the effectiveness of the
individual toxicity screening criterion is substantially
limited for a large proportion of the chemicals identified
on the 37 lists. Nevertheless, because all chemicals with
cancer toxicity values are considered high hazard for this
portion of the analysis, no chemicals would be screened out
on the basis of carcinogenicity.
The toxicity screening reduced the number of chemicals
dramatically from the original universe of over 2300. As
noted above, this reduction is primarily a function of the
relatively small number of chemicals (about 400) for which
human or ecotoxicity data are available. The screened list
contains about one-third (25/74) of the chemicals for which
CSFs were available, and about one-quarter (13/52) of those
for which inhalation unit risks are available. The chemicals
with low (<50th percentile) RfDs comprise by far the largest
(107) set of all the chemicals identified by the toxicity
screening, representing about one-third of the total number
of chemicals for which RfDs have been derived. A large
proportion of these chemicals are pesticides. Relatively few
chemicals were identified having low inhalation RfCs and
AWQCs for aquatic life.
Exhibit 4-6 summarizes the results of the screening of
chemicals with regard to fate and transport properties. The
first two columns address the potential to volatilize for
soil and water, as indicated by the vapor pressure and
Henry's Law constant. Since these parameters are directly
related, the chemicals in these two columns overlap
substantially. The next column lists chemicals with soil or
water column degradation constants less than 0.5/year. Since
the values for these two media are close for most of the
chemicals, separate columns are not provided for each
medium. The final three columns identify the chemicals with
relatively high aquatic BCFs, beef biotransfer factors, or
Kows. Since all three of these values are related to
partitioning between lipid and water phases, the chemicals
in these three columns also overlap substantially.
As was the case for the toxicity screens,
consistently-derived fate and transport parameters are not
available to screen the majority of the chemicals. Thus, the
menu of chemicals that are identified by the screening
criteria related to each individual parameter again is
determined primarily by the availability of data. In the
case of the fate and transport screening, fewer chemicals
are identified as being potentially hazardous. In addition,
the fate and transport screening identifies a smaller
proportion of the chemicals for which data are available. In
all cases, the chemicals exceeding the screening criteria
represent less than 10 percent of the chemicals for which
data are available.
4.3.4     Release Volume Screening of Possible Non-Hazardous
Industrial Waste Constituents
Chemicals not screened out by the toxicity or fate and
transport criteria were screened against the 1994 TRI data
(used as a proxy for occurrence in wastes). The results of
this final screening are presented in Exhibit 4-7. Of the
151 unique chemicals or classes of chemicals that were
identified in the toxicity or fate and transport screening,
TRI release data were available for 24 of them. Five of
these chemicals (Freon 113, 1,3-butadiene, chlorine dioxide,
chloroprene, and propylene dioxide) had TRI releases above
one million pounds in 1994. Nineteen of the chemicals had
TRI releases less than a million pounds. This latter group
of chemicals were eliminated from further analysis. As noted
previously, the remaining 132 chemicals for which no TRI
data were available were retained in the analysis.
4.3.5     Summary of Possible Non-Hazardous Industrial Waste
Constituents
Exhibit 4-8 summarizes the results of the TRI screening
process. It places the possible non-hazardous waste
constituents into the same chemical categories as were used
to characterize the known non-hazardous industrial waste
constituents in Exhibit 4-2. The largest number of possible
waste constituents (74) are pesticides and related
compounds. As discussed in Section 4.3.2, these chemicals
are identified as being potentially hazardous primarily by
virtue of low RfDs, although there are also some potent
ecotoxins, as well as persistent and bioaccumulative
chemicals, among this group.
The next most numerous category among the possible
constituents are the other semivolatile organic chemicals.
This diverse group includes chemicals recognized both for
their toxicity and their fate and transport properties.
Twelve metals/inorganic elements or groups are identified
including five different thallium salts. Similarly, the
other volatile organics group includes 5 nitrosamines among
a total of 13 compounds. Also included in this group are two
very toxic organometallic compounds, methyl mercury and
tetraethyllead. Among the seven chlorinated organics are two
of the five chemicals with TRI releases greater than one
million pounds (Freon 113 and chloroprene). No other
chemical category is represented by more than five
chemicals.
4.4  Combine and Screen Known and Possible Non-Hazardous
Industrial Waste Constituents
In this section, the known (from Section 4.2) and possible
(from Section 4.3) non-hazardous industrial waste
constituents are combined and screened against toxicity,
fate, and transport criteria. Unlike the prior section,
screening is oriented more toward groups of chemicals rather
than toward individual chemicals, and toward comparing the
properties of known versus possible non-hazardous industrial
waste constituents. There is, in addition, another screening
step related to potential for occurrence in wastes, namely,
comparison to 1994 non-confidential TSCA production volume
data.
4.4.1     Combine the Lists
The lists of known and possible non-hazardous industrial
waste constituents are shown in Exhibits 4-2 and 4-8.
Exhibit 4-9 summarizes the screening of the known
non-hazardous industrial waste constituents in the same way
that Exhibit 4-7 provides these data for the possible
constituents. As seen in these exhibits, the distribution of
chemicals within chemical classes is somewhat different
between the known and possible non-hazardous industrial
waste constituents. These differences, however, are
exaggerated by the removal of the known constituents from
consideration as possible constituents. (Logically, a
chemical cannot be both a "known" and "possible" waste
constituent.)  The known non-hazardous industrial waste
constituents are distinguished by a relatively high
proportion of metals and inorganics, chlorinated volatile
organics, other volatile organics, and polycyclic aromatic
hydrocarbons, compared to the possible non-hazardous waste
constituents. In contrast, pesticides and related compounds
constitute a much higher proportion of the possible
non-hazardous industrial waste constituents than the known
constituents.
The pattern of differences in chemical category can be
partially explained by the differences in the data sources.
The relatively high prominence of volatile organics among
the possible constituents probably reflects the difficulties
in controlling fugitive releases of these high-volume
chemicals during storage and processing. Such chemicals are
somewhat less likely to turn up in groundwater samples (in
the release descriptions or in aqueous effluents) because of
their high volatility. The prominence of the less volatile
organics in the known non-hazardous industrial waste
constituents again reflects the greater stability of these
chemicals in solid and liquid wastes.
Exhibit 4-9 also shows that the known waste constituents
include a much higher number of chemicals with TRI release
values greater than one million pounds (45) than is found
among the possible constituents (5). This is primarily due
to the fact that the known waste constituents were
identified first. Many of the high TRI release chemicals
also would have been identified as possible non-hazardous
industrial waste constituents if they had not been
identified as known constituents. The implications of these
findings for the potential severity of gaps in the hazardous
characteristics are discussed in more detail in Chapter 10.
In the analysis that follows, the known and possible
non-hazardous industrial waste constituent lists are
combined, and screened against single and multiple
parameters related to toxicity, fate and transport, and
release potential.
4.4.2     Screen Combined List Against Single Criteria
Quantitative Human Toxicity Indicators. Exhibit 4-10
summarizes the toxicological properties of the combined
known and possible non-hazardous industrial waste
constituents. The chemicals are screened using the same
criteria as described for the possible constituents alone in
Section 4.3, with the exception that additional criteria
related to carcinogenic potency are added (oral CSF and
inhalation UR > 50th percentile). The list of suspect
carcinogens (i.e., the first and third columns in Exhibit
4-10) contains a large proportion of all chemicals for which
EPA has developed CSFs and URs. The proportion of the
chemicals with high CSFs or URs (i.e., the second and fourth
columns) is likewise very near to one-half of the total
suspect carcinogens. This finding indicates that, as
expected, the large universe of chemicals initially screened
contains almost all of the chemicals that EPA has evaluated
as potential human carcinogens. Many classes of chemicals
(inorganics, volatile chlorinated organics, pesticides,
other volatile chemicals) are represented among the suspect
carcinogens.
Ecotoxicity. As shown in the last column of Exhibit 4-10, 18
of the combined known and possible constituents have low
AWQCs (below 50th percentile), indicating the potential for
adverse effects on aquatic organisms. Many of these
chemicals are pesticides, and most of the pesticides are
persistent chlorinated pesticides. Although most of these
chemicals are no longer produced, their presence among the
known non-hazardous industrial waste constituents may give
rise for some concern. Also included in this group are
selenium, silver, and hydrogen sulfide.
Potential Endocrine Disruptors. Because of the
rapidly-evolving state of knowledge regarding chemicals that
may act as endocrine disruptors, estrogen inhibitors, or
have other hormone-like effects, it is difficult to estimate
precisely how many of the combined known and possible
non-hazardous industrial waste constituents fall into this
category. Based on the rather broad list of potential
endocrine disruptors, 23 of the combined constituents are
implicated as being potential endocrine disruptors (Exhibit
4-11). (Nine of the TC analytes are also potential endocrine
disruptors.)  Because of the lack of knowledge concerning
dose-response relationships for exposures to single and
multiple endocrine disruptors, it is difficult to predict if
these chemicals would present risk to humans and non-human
receptors. Nevertheless, the fact that so many of these
chemicals are present among the constituents may cause
concern.
Potential for Frequent Occurrence in Wastes. The combined
list of known and possible non-hazardous industrial waste
constituents were also searched to identify those chemicals
with high potential for occurrence in wastes, as indicated
by TRI releases and/or non-confidential TSCA Inventory
production data. The results of this analysis are summarized
in Exhibit 4-12. Constituents are included in the table only
if either TRI release data or non-CBI TSCA inventory data
are available for them.
Volatility and Persistence. As discussed in Section 3.5,
volatility and persistence appear to be key indicators of
potential risks for the TC analytes. In the first four
columns of Exhibit 4-13, the known and possible
non-hazardous industrial waste constituents are screened
against these properties. Vapor pressure of 1.3x10-3
atmosphere (which is approximately equivalent to 1 mm Hg) is
used to identify volatile chemicals. This measure
approximates the potential to volatilize; many chemicals
with lower vapor pressure could volatilize readily under
certain waste management conditions. Even so, 70 known or
possible non-hazardous industrial waste constituents fall
into this category. This finding suggests that, as for the
volatile TC analytes, volatilization releases and inhalation
exposures (and possibly indirect exposures) may be a concern
for some of these chemicals.
Two chemicals, both chlorinated organics, are identified as
having long half-lives (greater than 0.15 year) in air. This
finding does not mean that all of the other constituents are
too short-lived to be of concern through air exposures.
Half-lives on the order of a few hours or days also may be
of concern in terms of direct inhalation exposures. This
criterion is more indicative of the potential for long-range
(e.g., regional or global-scale) transport of these
chemicals in the vapor phase. Also, as noted in Section 3.5,
the air half-lives of many of the inorganic waste
constituents (especially the metals) bound to particulates
would also be limited only by how long the particles
remained suspended in the atmosphere.
The third column of Exhibit 4-13 identifies the
non-hazardous industrial waste constituents that are
relatively persistent either in soils or in the water
column. The metals all fall into this category, along with
the PAHs, many chlorinated pesticides, and 2,3,7,8-TCDD. The
only volatile organic chemical in this category is
1,2-dichloropropane. Appearance in this category arouses
concern for potential inhalation and indirect pathway
exposure risks, as discussed in Section 3.5.
A high Kow, as indicated in the fourth column, indicates a
high potential to bind to soil organic matter. It is highly
correlated with the tendency to bioaccumulate. Thirty-one of
the known and possible waste constituents including many
persistent pesticides and PAHs, are in this category.
Bioaccumulation Potential. The last three columns of Exhibit
4-13 indicate the potential for bioaccumulation by the known
and possible non-hazardous industrial waste constituents in
aquatic and terrestrial food chains. The constituents with
aquatic BCFs or BAFs greater than 1,000 are limited to the
chlorinated pesticides, several phthalate esters, and
diethylstilbestial (DES). This finding does not imply that
no other constituents present significant risks through
indirect pathways; nevertheless, the identified chemicals
are all clearly recognized as being problematic from the
point of view of bioconcentration. If these chemicals were
released in significant amounts from non-hazardous waste
industrial management activities, they could present
substantial risks through food-chain exposures.
The last column of the table lists chemicals that are taken
up from feed by beef cattle with above-average (greater than
75th percentile) efficiency. This list includes most
chemicals that also are of potential concern for aquatic
ecosystems. Also, several additional classes of chemicals
are identified, including the metals and PAHs. Although the
beef biotransfer factor is only one of many parameters
determining the potential for risks to humans from beef
consumption, it is a reasonable indicator of potential
concern for this pathway and is a useful indicator of
exposure potential in other terrestrial food chains.
LNAPL and DNAPL Formation. The potential to form nonaqueous
phase liquids (NAPLs) is of great concern from the point of
view of waste management risks. Historically, NAPLs have
been serious problems in the remediation of hazardous waste,
because of their high potential risks and high remediation
costs. Any chemical that is relatively insoluble in water
and is a liquid at ambient temperature can be the principal
component of a NAPL. If the chemical or chemical mixture is
denser than water, then a dense nonaqueous phase liquid
(DNAPL) is formed. If the liquid is less dense than water, a
light nonaqueous phase liquid (LNAPL) may be formed.
DNAPLs are of particular concern because, when they escape
to groundwater, they will sink through the unsaturated zone
or aquifer until they encounter bedrock or another barrier.
They can remain at the bottom of the aquifer (for example,
in bedrock fractures) where they are hard, or in some cases
nearly impossible, to remediate. Most DNAPLs undergo only
limited degradation in the subsurface, and persist for long
periods while slowly releasing soluble organic constituents
to groundwater. Even with a moderate DNAPL release,
dissolution may continue for hundreds of years or longer
under natural conditions before all the DNAPLs are
dissipated and concentrations of soluble organics in
groundwater return to background levels. When released into
surface water, DNAPLs tend to sink to the bottom and
contaminate sediments. LNAPLs, in contrast, will tend to
float on the surface of an aquifer, where they are easier to
remedy; yet, they also can contaminate large volumes of
groundwater through slow dissolution. Both LNAPLs and DNAPLs
also can facilitate the transport of toxic waste
constituents by solubilizing chemicals that would otherwise
be immobile in waste or soil matrices.
It is difficult to predict the circumstances under which
LNAPL and DNAPL formation will occur and pose a risk to
human health or the environment. Whether significant amounts
of NAPLs will form depends on the composition of the wastes
and the management practices employed. Reports of nonaqueous
phase liquids were not found among the release descriptions
for non-hazardous industrial waste management summarized in
Chapter 2, possibly due to limitations in monitoring
requirements. EPA has recently conducted a study of the
potential for DNAPL formation at hazardous waste (NPL)
sites, and identified several industries where NAPL
formation is particularly likely to occur. These industries
include wood treating sites, general manufacturing, organic
chemical production, and "industrial waste landfills". A
wide variety of chemicals have been found in NAPLs, and it
appears that if a chemical is to be the major constituent of
a NAPL, the most important requirements are relative
insolubility in water and liquidity at ambient temperatures.
Exhibit 4-14 identifies a number of the known and possible
non-hazardous industrial waste constituents with the
requisite physical properties. Since there is no clear
dividing line between chemicals likely and not likely to
form NAPLs, this list was developed using a combination of
professional judgment and information about the physical
properties of the waste constituents. All of the chemicals
listed are organics, have relatively low water solubilities,
and are liquid at room temperature (melting points greater
than 71C, boiling point greater than 301C). Those indicated
as being potential DNAPL formers have bulk liquid densities
greater than 1 gm/cc, while those with densities less than
water are indicated as potential LNAPL formers. The
distinction is not clear-cut however, as a mixture of light
and heavy constituents at different relative concentrations
might have widely varying densities.
Exhibit 4-14 identifies more potential DNAPL formers than
LNAPL formers found among the known and possible waste
constituents. Based on density considerations, the LNAPL
formers tend to be primarily the non-halogenated
hydrocarbons, including "BTEX" and compounds with similar
properties, whereas the DNAPL formers tend to be primarily
chlorinated and brominated chemicals. Not included in the
NAPL list are pesticides that also fulfill the physical
criteria, but which are no longer produced (see Chapter 9)
and thus are less likely to be present in significant
amounts in pure form in non-hazardous industrial wastes.
These findings suggest that, on physical bases alone, many
of the known and possible non-hazardous industrial waste
constituents could form LNAPLs or DNAPLs. As noted above,
however, when this actually occurs depends to a large degree
on the specific characteristics of the wastes and waste
management practices.
EPA's analysis of DNAPL formation at NPL sites found that
the contaminants most directly associated with DNAPL
presence include creosote compounds, coal tar compounds,
polychlorinated biphenyls (PCBs), chlorinated solvents, and
mixed solvents.
     4.4.3     Screen Combined List Against Multiple
Parameters
This section discusses the results of one last round of
screening conducted on the entire combined list of known and
possible non-hazardous industrial waste constituents. This
analysis combines toxicity, persistence, volatility, and
bioaccumulation screens in various combinations in order to
identify the chemicals most likely to pose risks by various
exposure pathways. Only constituents in the intersections of
the screens remain (e.g., only constituents that are
persistent and highly toxic). For human toxicity, the
criteria have been applied in the following order:
!    Persistent and Highly Toxic to Humans. This combination
is intended to identify highly toxic chemicals that could
pose risks through any pathways involving long-term release
and transport of contaminants, such as groundwater and
indirect pathways involving air, surface water, or
groundwater releases.
!    Persistent, Highly Toxic to Humans and Bioaccumulative.
This screen narrows the above waste constituents to those
with potential for adverse effects through indirect food
chain exposure.
!    Persistent, Highly Toxic to Humans, Bioaccumulative,
and Volatile. This combination further narrows the above
chemicals to those with potential to cause indirect pathway
risks through air releases.
A fourth screen applied persistent, ecotoxic, and
bioaccumulative criteria to the combined list of
constituents. This combination of screening criteria is
intended to identify chemicals for which potential harm to
ecological receptors is a potential concern.
The individual criteria used in combination are described in
Section 4.3. The persistence screen consisted of a
determination of whether the chemicals had soil or water
column degradation rate constants of less than 0.5/year.
"Highly toxic" indicates any chemical having a CSF or Unit
Risk above the 50th percentile of all chemicals, or a
chronic RfD below the 50th percentile. Volatility was
screened against Henry's Law constant of 10-5 atm-m3/mole,
and bioaccumulation potential determined by an aquatic BCF
or BAF value of greater than 1,000 L/Kg.
The results of the combined screening of known and possible
non-hazardous industrial waste constituents are summarized
in Exhibit 4-15. To a substantial degree, these results
parallel the screening-level modeling results for the TC
analytes discussed in Section 3.5. Four of the nine
persistent and highly toxic chemicals are chlorinated
pesticides or degradation products, along with three metals
(antimony, beryllium, and molybdenum), benzo(a)pyrene, and
2,3,7,8-TCDD. The appearance of benzo(a)pyrene suggests that
other high molecular weight PAHs (some of which are also
carcinogens) might also pass this screen if CSF values were
available for these compounds. In addition, several other
chlorinated pesticides have properties that just miss the
toxicity or persistence cutoff values.
When bioaccumulation potential is added to the screening
conditions (second column of Exhibit 4-15), no chemicals
drop out. This finding shows the high correlation between
persistence and bioaccumulative potential:  if a chemical
was not persistent, it would lack the opportunity to
accumulate in environmental media or tissue.
When the criterion of volatility is added to the preceding
screens, three chemicals, all persistent pesticides remain.
This result again parallels the results seen for the TC
analytes in Section 3.5. If vapor pressure cutoff (1 mm Hg),
rather than Henry's Law constant (10-5 atm.-M3/mole) is used
to characterize the potential to volatilize, none of the
chemicals qualify in this category.
The last column of Exhibit 4-15 identifies persistent,
bioaccumulative, and ecotoxic chemicals. As might be
expected from the previous screening results, these
chemicals include chlorinated pesticides and 2,3,7,8-TCDD.
Because the AWQC screen is based only on harmful
concentrations, it does not include any screening for the
concentrations normally encountered in the environment.
Thus, if a much less toxic chemical (for example zinc or
copper) were released into the environment in much larger
amounts than the pesticides, the exposure concentrations
might be much greater and adverse effects on ecological
receptors might occur.
4.5  Driving Risk Pathways for the Known and Possible
Non-Hazardous Industrial Waste Constituents
EPA has previously evaluated the potential risks associated
with the management of many known and possible non-hazardous
industrial waste constituents in the context of deriving
proposed risk-based exit levels for the proposed HWIR-Waste
rulemaking. As discussed in Section 3.5, these proposed exit
levels were derived by back-calculating concentrations in
wastewaters and nonwastewaters corresponding to acceptable
risk levels. The magnitude of the modeled exit levels is
inversely proportional to the magnitude of risk posed by the
chemical when placed in the specified management units.
Proposed exit levels are calculated for groundwater
exposures and other pathways. Thus, the proposed exit levels
also indicate the relative importance of the exposure
pathways for each chemical.
Exhibit 4-16 tabulates the exit levels for 128 of the known
or possible non-hazardous industrial waste constituents
(i.e., the entire combined list prior to any screens that
were also addressed in the HWIR-waste proposed rulemaking),
and the exposure pathways that were risk drivers for setting
the exit levels. As in the case of the similar analysis for
the TC analytes in Section 3.5, many of the known or
possible non-hazardous industrial waste constituents have
proposed exit levels that are quite low (68 are below 0.1
mg/l). Therefore, the Agency has determined that the
presence of these constituents in wastes at even relatively
low concentrations may pose significant risks to human
health. Again it should be noted that the target cancer risk
level used to derive the exit levels was 10-6, rather than
the 10-5 level used in the derivation of TC regulatory
levels. Even so, these levels indicate potential cause for
concern for many of these chemicals at even low
concentrations in wastes.
     As was also the case for the TC analytes,
non-groundwater pathway risks drive the establishment of
exit levels for about one-quarter of the known or possible
non-hazardous industrial waste constituents. The driving
pathways include direct inhalation and vegetable and milk
ingestion. Pesticides make up a large proportion of the
chemicals for which non-groundwater pathways drive the
risks, but many volatile chlorinated and nonchlorinated
organics also fall into this category. Ecological, rather
than human health risks, drive the setting of proposed exit
levels for two chemicals (copper and parathion). These
findings confirm the indications from the toxicity and fate
and transport screening presented in the previous sections
that inhalation and indirect pathways could be of concern
for many of the known or possible non-hazardous industrial
waste constituents.
4.6  Potential Acute Hazards Associated With Known and
Possible Non-Hazardous Industrial  Waste Constituents
To this point, the evaluation of the potential hazards
associated with the possible and known non-hazardous
industrial waste constituents has focused on chronic toxic
effects. As discussed in Chapter 3, waste constituents may
also pose risks from acute exposures, as well as from
physical hazards associated with reactivity, flammability,
or corrosivity. To investigate the possibility of acute
adverse effects, the Agency has compared list of the known
and possible waste constituents to lists developed by the
EPA and other regulatory agencies that identify such
hazardous properties. The results of this comparison are
summarized in Exhibit 4-17.
As shown in the exhibit, 38 of the known and possible
non-hazardous industrial waste constituents have been
identified in one or more regulatory contexts as being
acutely toxic. Although most of these chemicals are volatile
organics, several acid gases and other inorganic compounds
also are included. Appearance on these lists does not
automatically indicate that acute adverse effects will
occur, only that such effects could potentially be
associated with management of wastes containing these
chemicals.
Fifteen of the waste constituents are also identified as
being highly flammable. These are mostly volatile organics,
along with a few inorganic gases and liquids. They
substantially overlap with the previous list. Only two of
the known or possible non-hazardous industrial waste
constituents are identified as being highly reactive.
4.7  Identify Individual Chemicals and Classes of Chemicals
Constituting Potential Gaps
The analyses in the previous sections help to clarify the
nature of potential gaps in the hazardous waste
characteristics associated with specific chemicals and
chemical classes related to chronic human health risks and
ecological risks. The analyses identified groups of
chemicals most likely to be present in non-hazardous
industrial waste, and screened them in terms of their
toxicity, fate, and transport properties. The results of the
proposed HWIR-waste modeling were reviewed, where available,
to confirm and expand the findings of the screening results.
Finally, the known and possible non-hazardous industrial
waste constituents were reviewed with regard to their
potential to cause acute adverse effects. As a result of
these efforts, a number of potential gaps have been
identified, as summarized in Exhibit 4-18.
This listing of potential gaps for non-TC analytes should
not be taken as being either exhaustive or definitive. These
gaps are potential, not actual gaps. They have been
identified for purposes of targeting further analysis, not
for purposes of choosing what constituent or wastes to
regulate. Other potential gaps related to natural resource
damages and regional or global environmental problems are
discussed in Chapter 5. Also, Chapter 6 describes how
several states have expanded the TC, implicitly identifying
gaps in the TC. In Chapter 10, some of the unresolved issues
identified in Exhibit 4-18 are discussed and the available
information about the potential significance of these
impacts is reviewed in detail.
EPA recognizes the limitations of this analysis. As noted
previously, the data concerning the composition of
non-hazardous industrial wastes are quite limited and
generally quite old. This lack of data in large part
explains the need for the elaborate screening procedures
employed in this chapter. Few data are available on the
current patterns of non-hazardous industrial waste
generation, management, and disposal. In addition, the
chemical-specific screening is further complicated by the
lack of toxicity and fate and transport parameter data for a
large proportion of the universe of possible waste
constituents, which necessitated extensive use of
professional judgment to supplement the screening process.
CHAPTER 4. POTENTIAL GAPS ASSOCIATED WITH NON-TC CHEMICALS.
            . . . . . .4-1
4.1  Overview of Methodology. . . . . . . . . . . . . . .4-1
Step 1:  Identify and Classify Known Non-Hazardous
         Industrial Waste Constituents   4-1
Step 2:  Identify and Screen Possible Non-Hazardous
         Industrial Waste Constituents   4-1
Step 3:  Apply Hazard-Based Screening Criteria . . .4-3
Step 4:  Review Relevant Multipathway Risk Modeling
         Results   4-3
Step 5:  Identify Potential Acute Hazards. . . . . .4-3
Step 6:  Summarize Findings. . . . . . . . . . . . .4-3
4.2  Identify and Classify Known Constituents of
     Non-Hazardous Industrial Wastes   4-3
4.3  Identify Possible Non-Hazardous Industrial Waste
     Constituents of Potential Concern   4-7
4.3.1     Approach to Identifying Potentially Hazardous
          Chemicals  4-7
4.3.2     Screening Approach . . . . . . . . . . . .4-9
4.3.3     Toxicity, Fate, and Transport Screening for
          Possible Non-Hazardous Industrial Waste
          Constituents   4-12
4.3.4     Release Volume Screening of Possible Non-Hazardous
         Industrial Waste Constituents   4-15
4.3.5     Summary of Possible Non-Hazardous Industrial Waste
         Constituents  4-20
4.4  Combine and Screen Known and Possible Non-Hazardous
     Industrial Waste Constituents   4-20
4.4.1     Combine the Lists. . . . . . . 4-20
4.4.2     Screen Combined List Against Single Criteria4-26
4.4.3     Screen Combined List Against Multiple Parameters
                    4-34
4.5  Driving Risk Pathways for the Known and Possible
     Non-Hazardous Industrial Waste Constituents   4-35
4.6  Potential Acute Hazards Associated With Known and
     Possible Non-Hazardous Industrial  Waste
     Constituents   4-36
4.7  Identify Individual Chemicals and Classes of Chemicals
   Constituting Potential Gaps  4-41
Exhibit 4-1    Flow Chart of Procedures Used to Identify
               Non-TC Chemicals Posing Potential Gaps in the
              TC Characteristics    4-2
Exhibit 4-2    Known Non-Hazardous Industrial Waste
               Constituents Chemicals Found in Case Studies,
              ISDB, Listings Documents, Effluent Guideline
            Documents by Chemical Class and Listing
            Documents  4-6
Exhibit 4-3    Lists Used to Identify Possible Non-Hazardous
              Industrial Waste Constituents   4-8
Exhibit 4-4    Criteria Considered for Screening
               Non-Hazardous Industrial Waste
               Constituents   4-10
Exhibit 4-5    Toxicity Screening Results for Possible
               Non-Hazardous Industrial Waste
               Constituents   4-13
Exhibit 4-6    Persistence and Bioconcentration/
               Bioaccumulation Screening Results for
               Possible Non-Hazardous Industrial Waste
               Constituents   4-16
Exhibit 4-7    Screening of High-Toxicity, Persistent,
               Bioaccumulative/Bioconcentrating Possible
               Non-Hazardous Industrial Waste Chemicals
               Against TRI Release Volumes   4-17
Exhibit 4-8    List of Known and Possible Non-Hazardous
               Industrial Waste Constituents By Chemical
               Class    4-21
Exhibit 4-9    Screening of Known Non-Hazardous Industrial
               Waste Constituents Against TRI Release
               Volumes   4-22
Exhibit 4-10   Toxicity Summary of Known and Possible
               Non-Hazardous Industrial Waste Constituents
                        4-27
Exhibit 4-11   Potential Endocrine Disruptors. . .  4-28
Exhibit 4-12   TRI Releases and TSCA Production Volume Data
             for the Known and Possible Non-Hazardous
             Industrial Waste Constituents   4-29
Exhibit 4-13   Volatility, Persistence, and Bioaccumulation/
               Bioconcentration Potential of Known and
               Possible Non-Hazardous Industrial Waste
               Constituents    4-30
Exhibit 4-14   LNAPL/DNAPL Formation Potential of Known and
             Possible Non-Hazardous Industrial Waste
             Constituents       4-33
Exhibit 4-15   Multiple Screening Criteria Applied to Known
             and Possible Non-Hazardous Industrial Waste
             Constituents   4-35
Exhibit 4-16   Lowest Proposed HWIR-Waste Exit Levels for
               Known and Possible Non-Hazardous Industrial
               Waste Constituents   4-37
Exhibit 4-17   Potential Acute Hazards Associated with Known
              and Possible Non-Hazardous Industrial Waste
              Constituents   4-40
Exhibit 4-18   Potential Gaps in the Hazardous Waste
               Characteristics Identified Based on the
               Hazardous Properties of Known and Possible
               Non-Hazardous Industrial Waste Constituents
                     4-42
CHAPTER 5. POTENTIAL GAPS ASSOCIATED WITH NATURAL RESOURCE
           DAMAGES AND LARGE-SCALE ENVIRONMENTAL PROBLEMS
This chapter discusses risks associated with non-hazardous
industrial waste management that are not addressed in
Chapters 3 or 4. Chapter 3 examined potential gaps inherent
in the current hazardous waste characteristics, thereby
focusing on the adverse effects that the characteristics
were meant to address, namely risks arising primarily from
acute events such as fires, explosions, and acute exposures
of waste management and transportation workers, and health
risks caused by local environmental contamination near waste
management units. Chapter 4 examined potential gaps
associated with adverse human health or localized ecological
effects from constituents not included in the toxicity
characteristic. This chapter addresses a third set of risks
associated with non-hazardous industrial waste management.
!    Section 5.1 addresses the pollution of groundwater by
constituents that diminish the value and usability of the
resource without threatening human health;
!    Section 5.2 addresses damage from non-hazardous
industrial waste management to air quality through odors
that harm the quality of life but may not have severe health
effects; and
!    Section 5.3 examines possible contributions to regional
and global environmental problems from the management of
non-hazardous industrial waste, including:  air deposition
to the Great Waters, damages from airborne particulates,
global climate change, potential damage from endocrine
disruptors, red tides, stratospheric ozone depletion,
tropospheric ozone and photochemical air pollution, and
water pollution.
These environmental problems may or may not meet the RCRA
statutory or regulatory definitions of the types of risks
that the hazardous waste management program is meant to
address.
5.1  Damage to Groundwater Resources
As noted in Chapter 2, the most common and well-documented
impact of releases from non-hazardous industrial waste
management is groundwater contamination. If contamination is
present at high enough concentrations, the use of the
groundwater as a water supply for human consumption or other
use may result in adverse effects on health. Human health
risks associated with exposure to toxic pollutants are not
the only concern associated with groundwater contamination,
however. Non-toxic pollutants such as iron, chloride, or
total dissolved solids may be present in concentrations that
damage the aesthetic qualities and usability of the water
without posing outright health hazards. In areas where
groundwater is used as a drinking water supply, such water
pollution must be remediated, limitations must be placed on
its use, and/or alternative sources must be found. These
actions may be expensive and strain existing water supplies.
Where alternative supplies are not economically available,
groundwater resources of marginal quality, which do not
exceed health-based levels, may continue to be used. Even
where the polluted groundwater is not used for drinking
water, the value of the resource may decline because it is
no longer available for future use as drinking water without
remediation.
This non-toxic pollution of groundwater from non-hazardous
industrial waste management was found relatively often in
the environmental release descriptions summarized in Chapter
2. Seventy-five (84 percent) of the 89 release descriptions
with data on regulatory levels had constituents detected at
levels exceeding non-health-based or non-ecologically-based
standards, principally on aesthetic or usability criteria
developed under the Safe Drinking Water Act as Secondary
Maximum Contaminant Levels (SMCLs). Releases at 70 of these
75 sites also exceeded health and/or ecological-based
standards. Of the 177 non-TC constituents identified in the
release case studies, 9 constituents (plus pH and total
dissolved solids) have SMCLs. (Some of these constituents
also have health-based or ecologically-based levels.)
Exhibit 5-1 lists all constituents with SMCLs and shows how
frequently they were found among the 89 case studies where
concentration and regulatory standards data were available.
The most commonly detected constituents, iron, chloride, and
manganese, all have SMCLs. Also, all SMCLs, except those for
foaming agents, color, and corrosivity, were violated by at
least several documented releases. (See Exhibit 2-6 for
additional data on the concentrations at which these
constituents were detected.)
5.2  Damage to Local Air Quality from Odors
Noxious odors historically have been reported in the
vicinity of waste management facilities. Odor problems have
caused minor health problems, reduced the quality of life,
and reduced property values near such facilities.
Information on the extent of such problems from
non-hazardous industrial waste management is very limited.
Odor problems were reported in several of the release
descriptions initially identified by EPA, but these cases
were excluded because they did not meet the Agency's strict
selection criteria. Only one release description included
reports by residents of odor problems. Nevertheless, the
case study development methodology may have missed many
cases of odor problems from non-hazardous industrial waste
management facilities because state regulatory programs
largely focus on groundwater concerns. Also, odor problems
are often handled at the local level and thus the states may
not get involved.
The potential for odor problems clearly exists at
non-hazardous industrial waste facilities that manage
certain types of wastes. For example, food processing
facilities (e.g., slaughterhouses that must dispose of offal
and alimentary contents from slaughtered animals) may have
odor problems if their air releases are not carefully
managed. In addition to food wastes, potential odor problems
may arise from chemical wastes. Exhibit 5-2 lists a number
of the chemicals identified in the release descriptions
(although not necessarily for odor) that have extremely low
odor thresholds in either air or water. Ten of these
chemicals have threshold odor concentrations in air (the
lowest concentrations at which odors can be detected or
recognized) of 0.01 mg/m3 or less, and six of them can be
detected by odor in water solutions at concentrations of
0.006 mg/l or less.
Because odor problems typically are handled locally and
these problems likely do not meet the RCRA definition of
risks meant to be addressed by the hazardous waste
management program, EPA does not plan to investigate this
area further following the Scoping Study.
5.3  Large-Scale Environmental Problems
EPA considered whether any major large-scale environmental
problems (e.g., global climate change, potential damage from
endocrine disruptors) might be caused, at least to some
extent, by non-hazardous industrial wastes. Depending on the
types of wastes and on the relative contributions of these
wastes to the problem areas, changes in the hazardous waste
characteristics might be one method to help reduce further
damages.
EPA began this phase of the Scoping Study by developing an
initial list of major large-scale environmental problems (or
possible problems) that have potential links to
non-hazardous industrial wastes (see Exhibit 5-3). Several
of these problems overlap considerably with each other and
with exposure and other damage pathways discussed
previously. Furthermore, EPA recognizes that other
environmental problems have potential links to non-hazardous
industrial waste; however, given the limited resources
available for this Scoping Study, the Agency chose to limit
this analysis to some of the more likely areas of concern.
Following the development of this list, EPA conducted
preliminary evaluations of the problem areas to try to
characterize the contributions to the problems from
non-hazardous industrial wastes. Because these problems are
typically characterized by highly complex interactions of a
large number of factors, determining the exact contribution
of non-hazardous industrial wastes to each problem is
difficult and beyond the scope of this study. Instead, EPA
was able to conduct only initial evaluations to identify
areas that may have a significant contribution from
non-hazardous industrial wastes and thus may warrant further
analysis following the Scoping Study.
For environmental problems with a possible link to
non-hazardous industrial wastes, EPA identified (where
possible) the industries and waste streams that could be
contributing to the problems and the relevant statutes and
programs that are addressing the areas. The environmental
problems evaluated for this Scoping Study are discussed
below in the order (alphabetical) listed in Exhibit 5-3.
5.3.1     Air Deposition to the Great Waters
Pollutants emitted into the atmosphere are transported
various distances and can be deposited to aquatic ecosystems
far removed from their original sources. Studies show that
significant portions)often greater than 50 percent)of
pollutant loadings to the Great Waters (i.e., Great Lakes,
Lake Champlain, Chesapeake Bay, and coastal waters) are from
atmospheric deposition. Thus, this pathway is an important
factor in the degradation of water quality and the
associated adverse health and ecological effects. Because of
the mounting concern that air pollution contributes to water
pollution, Congress included Section 112(m), Atmospheric
Deposition to Great Lakes and Coastal Waters, in the Clean
Air Act Amendments of 1990.
Both local and distant air emission sources contribute to a
pollutant load at a given location. The sources of concern
for the Great Waters primarily include industrial activities
and processes involving combustion. At present, however, a
complete and comprehensive inventory of the locations of
particular sources and the amount of individual toxic
pollutants that each source emits to the air is lacking.
Nevertheless, EPA has identified several known air
pollutants of concern for Great Waters. Exhibit 5-4 lists
these pollutants and selected U.S. sources. Most pollutants
in this exhibit are TC analytes, while a smaller set are
chemicals (or chemical groups) of concern discussed in
Chapter 4. Thus, these pollutants are likely candidates for
further analysis as potential gaps in the hazardous waste
characteristics.
5.3.2     Airborne Particulates
Airborne particulate matter (PM) is one of the six
high-priority research topics identified for the next few
years by the EPA Office of Research and Development (ORD).
PM includes dust, dirt, soot, smoke, and liquid droplets
directly emitted into the air by sources such as factories,
power plants, transportation sources, construction activity,
fires, and windblown dust. Concern regarding PM from
non-hazardous industrial waste includes toxic constituents
entrained on particulates. PM is also formed in the
atmosphere by condensation or transformation of emitted
gases such as sulfur dioxide, nitrogen oxides, and volatile
organic compounds into small droplets.
Based on studies of human populations exposed to high
concentrations of particles (often in the presence of sulfur
dioxide) and on laboratory studies of animals and humans,
the major concerns for human health include effects on
breathing and respiratory symptoms, aggravation of existing
respiratory and cardiovascular disease, alterations in the
body's defense systems against foreign materials, damage to
lung tissue, carcinogenesis, and premature death. The major
subgroups of the populations that appear likely to be most
sensitive to the effects of particulate matter include
individuals with chronic obstructive pulmonary
cardiovascular disease, individuals with influenza,
asthmatics, the elderly, and children. Particulate matter
may injure crops, trees and shrubs, and may damage metal
surfaces, fabrics, and other materials. Fine particulates
also impair visibility by scattering light and reducing
visibility. The haze caused by fine particles can diminish
crop yields by reducing sunlight.
PM is increasingly being identified as posing a high
potential for health and environmental risk and other
potential damages. Nevertheless, EPA does not believe that
PM is a significant waste characterization issue but rather
a waste management issue. Furthermore, other programs (e.g.,
CAA National Ambient Air Quality Standards) are designed to
address this area. Therefore, airborne particulates are not
planned for further study as a potential gap.
5.3.3     Global Climate Change
Evidence is mounting that the increasing concentrations of
greenhouse gases (GHGs) will ultimately raise (and some
believe are currently raising) atmospheric and ocean
temperatures significantly, which may in turn alter global
weather patterns. Global climate already has changed over
the past century, and the balance of evidence suggests a
discernible human influence. Climate is expected to continue
to change in the future.
EPA conducted a brief review of the major anthropogenic
sources of the two predominant GHGs, carbon dioxide (CO2)
and methane (CH4), to determine the relative contributions
of non-hazardous industrial wastes, including their
co-disposal with municipal solid waste (MSW). Before
describing the results of this review, it is essential to
understand some of the international conventions used to
evaluate GHG emissions, as these conventions have a strong
bearing on the results.
The United States and all other parties to the Framework
Convention on Climate Change agreed to develop inventories
of GHGs for purposes of developing mitigation strategies and
monitoring the progress of those strategies. The
Intergovernmental Panel on Climate Change (IPCC) developed a
set of inventory methods to be used as the international
standard. The screening methodology used in this section to
evaluate emissions and sinks of GHGs attempts to be
consistent with IPCC's guidance.
One of the elements of the IPCC guidance that deserves
special mention is the approach used to address CO2
emissions from biogenic sources. For many countries, the
treatment of CO2 releases from biogenic sources is most
important when addressing releases from energy derived from
biomass (e.g., burning wood), but this element is also
important when evaluating waste management emissions (for
example, the decomposition or combustion of grass clippings
or paper). The carbon in paper and grass trimmings was
originally removed from the atmosphere by photosynthesis,
and under natural conditions, it would eventually cycle back
to the atmosphere as CO2 due to degradation processes. The
quantity of carbon that these natural processes cycle
through the earth's atmosphere, waters, soils, and biota is
much greater than the quantity added by anthropogenic GHG
sources. But the focus of the Framework Convention on
Climate Change is on anthropogenic emissions   emissions
resulting from human activities and subject to human control
 because these emissions have the potential to alter the
climate by disrupting the natural balances in carbon's
biogeochemical cycle.
Thus, for processes with CO2 emissions, if the emissions are
from biogenic materials and the materials are grown on a
sustainable basis, then those emissions are considered to
simply close the loop in the natural carbon cycle; that is,
they return CO2 to the atmosphere that was originally
removed by photosynthesis. In such cases, the CO2 emissions
are not counted (and thus most CO2 emissions from landfills
are not counted). On the other hand, CO2 emissions from
burning fossil fuels are counted because these emissions
would not enter the cycle were it not for human activity.
Likewise, CH4 emissions from landfills are counted, even
though the source of carbon is primarily biogenic. CH4 would
not be emitted but for the human activity of landfilling the
waste, which creates anaerobic conditions conducive to CH4
formation. This approach does not distinguish between the
timing of CO2 emissions, provided that they occur in a
reasonably short time scale relative to the speed of the
processes that affect global climate change. That is, as
long as the biogenic carbon would eventually be released as
CO2, it does not matter whether it is released virtually
instantaneously (e.g., from combustion) or over a period of
a few decades (e.g., decomposition on the forest floor).
CO2 accounts for the largest share of U.S. GHG emissions,
comprising 1,408 million metric tons of carbon equivalent
(MMTCE) out of total 1994 U.S. emissions of 1,666 MMTCE.
Combustion of fossil fuels results in the vast majority of
the CO2 emissions (1,390 MMTCE), with the remainder from
industrial processes such as cement production, lime
production, limestone consumption (e.g., iron and steel
production), soda ash production and use, and CO2
manufacture. CO2 emitted from landfills as a product of both
aerobic and anaerobic decomposition of organic wastes is not
counted, as described above.
Methane is the second most important GHG; U.S. emissions in
1994 were 166 MMTCE. Of the anthropogenic CH4 sources, the
largest is landfills (which contribute 36 percent of the
total U.S. methane emissions), agricultural activities (32
percent), coal mining (15 percent), production and
processing of natural gas and oil (11 percent), fossil fuel
combustion (3 percent), and wastewater treatment (0.6
percent). As explained above, CH4 from landfills is counted
as an anthropogenic GHG.
The majority of landfill CH4 emissions result from MSW
landfills (90 to 95 percent), with the remaining methane
emitted from the disposal of industrial wastes. Methane
emissions from large MSW landfills, however, are currently
regulated under EPA's recent New Source Performance
Standards and Emissions Guidelines, which require collection
and control of landfill gas. Small MSW landfills and
industrial waste monofills are not subject to these new
regulations and thus may warrant further investigation. This
is particularly true for small landfills or monofills
managing non-hazardous industrial wastes that have a high
biochemical oxygen demand (such as wastes from paper mills
and food processing), which have a high potential for
generating CH4.
In conclusion, non-hazardous industrial wastes may
contribute to GHG emissions to the extent that they are
highly degradable and either are disposed in small landfills
(which are not subject to the landfill gas rule) or are
released directly to the atmosphere. The emissions
attributable to these wastes are small compared to other
sources of GHGs. Nevertheless, the same highly putrescible
wastes that would be of concern when disposed in a landfill
environment are likely to cause taste and odor problems that
adversely affect local air and water quality. To a large
degree, the climate change risk (and much of the potential
groundwater resource damage) could be readily averted for
highly putrescible wastes by biological pretreatment prior
to land disposal to reduce the potential for (a) methane
formation and (b) production of odiferous compounds
generated in an anaerobic environment. Further research
could be conducted in this area to determine whether the
potential contribution of non-hazardous industrial wastes to
GHG emissions could be significant. However, given the
current coverage of this problem area by other programs
besides Subtitle C of RCRA, EPA does not plan to pursue
global climate change within the context of the hazardous
characteristics at this time.
5.3.4     Potential Damages from Endocrine Disruptors
Over the past decade, increased attention has been given to
a class of chemicals with high persistence, bioaccummulation
potential, and toxicity. These chemicals, often referred to
as PBTs, include a wide range of substances, generally
several metals and a variety of organic compounds. EPA's
involvement in PBT research and regulation has encompassed
many programs. One of these programs, waste minimization,
developed the Waste Minimization National Plan. This plan
established a national goal to reduce the most persistent,
bioaccumulative, and toxic chemicals in hazardous wastes by
25 percent by the year 2000 and by 50 percent by the year
2005. Currently many international organizations, including
the North American Commission for Environmental Cooperation
and various United Nations groups, are debating PBT public
policy and ultimately could generate binding commitments
(e.g., treaties) that could affect U.S. national policy on
PBTs. For example, an initial list of 12 PBTs is being
considered for control under an international protocol.
Recently, interest in PBTs has escalated due to the growing
attention on a subgroup of these chemicals called "endocrine
disruptors" (EDs). EDs are substances that have the
potential to interfere with hormonal systems in ecological
and human receptors. The results of such interference might
include adverse reproductive or developmental effects,
certain kinds of cancers, learning and behavioral problems,
and immune system deficiencies. Recent concern has focused
on the potential synergistic effects of EDs.
     Significant scientific debate still exists regarding
which chemicals are EDs and the degree to which EDs have
caused or have the potential to cause adverse human health
and environmental effects. This debate has prompted great
interest in researching the scope of ED impacts. For
example, the study of EDs is one of the six high-priority
research topics identified by EPA's Office of Research and
Development (ORD) for the next few years. It has also been
made a high priority by the U.S. chemical industry; the
Chemical Industry Institute for Toxicology (CIIT) has
reprogrammed much of its research budget into this area. To
the extent that the impact of EDs on the environment are
largely unknown, these chemicals may represent a substantial
gap in the hazardous waste regulations.
Notwithstanding the current debate, recent review articles
summarize convincing evidence that a variety of chemical
pollutants can act as endocrine disruptors in wildlife
populations. Some specific examples include the following:
!    Reptiles. Researchers found that the reproductive
development of alligators from Lake Apopka, Florida was
severely impaired, apparently due to DDE, a metabolite of
DDT and dicofol. The lake is located adjacent to an EPA
Superfund site where a dicofol spill had occurred. The
specific adverse effects included decreased testosterone and
abnormal testicular cells in males and increased estrogen
and altered ovaries (increased polyovular follicles and
polynuclear oocytes) in females.
!    Birds. A number of researchers have documented severely
impaired reproductive success in herring gulls from the
Great Lakes. Some specific observations include large clutch
sizes (attributed to nest sharing by two females),
female-female pair bonds, embryonic and chick mortality, and
altered nest defense and incubation behavior. These effects
were associated with high levels of organochlorines (e.g.,
DDT, dioxins, and mirex) in the 1960s and early 1970s.
Reproductive success increased as levels of these compounds
declined in the late 1970s and 1980s. Organochlorines that
have been identified as estrogenic to bird embryos in
laboratory studies include DDT and methoxychlor.
     In these cases, some of the causative agents appear to
be organochlorine pesticides that are no longer produced
(e.g., DDT) yet persist in the environment due to the nature
of their chemical/physical properties. Although these
chemicals are not generally expected to be components of
non-hazardous industrial wastes, a number of similar
chemicals currently used in industry have demonstrated
similar endocrine disrupting properties in laboratory
studies. These EDs are often present in treated sewage
effluent, and are likely to be components of non-hazardous
industrial waste.
A recent field study found that effluent from sewage
treatment works induced vitellogenin synthesis in male fish,
indicating that the effluent is estrogenic. The effects were
pronounced and occurred at all sites tested. The identity of
the chemical or chemicals in the sewage effluent causing the
effects is not known, however. A number of chemicals known
to be present in sewage effluent were tested for estrogenic
effects in fish. These chemicals included nonylphenol,
octylphenol, bisphenol-A, DDT, and PCBs. Furthermore, a
mixture of different estrogenic chemicals was found to be
considerably more potent than each of the chemicals when
tested individually, a finding that recently was replicated.
     In addition to the effects described above, other
documented endocrine disrupting effects in wildlife
populations from industrial effluents have unknown causative
agents. For example, kraft mill effluent caused a variety of
effects in two fish species:  white suckers and
mosquitofish. Lake Superior white suckers collected from a
site receiving primary-treated bleached kraft mill effluent
exhibited increased age to maturity, smaller gonads, lower
fecundity with age, and an absence of secondary sex
characteristics. Masculinization of female mosquitofish was
noted downstream from the discharge of kraft mill effluent
in Elevenmile Creek in Florida.
     Several of the chemicals identified in this section are
also identified in Chapter 4 as known or possible
non-hazardous industrial waste constituents. Some of the
relevant chemical groups are described in more detail below.
!    Alkylphenol Compounds. Alkylphenol-polyethoxylates are
non-ionic surfactants commonly used in industrial and
domestic detergents as well as some shampoos and cosmetics.
Alkylphenols are used as antioxidants in some clear
plastics. Alkylphenol-polyethoxylates are biodegraded to
alkylphenols during sewage treatment. These compounds
persist in rivers and their sediments and can migrate to
groundwater. These compounds also have the ability to
bioconcentrate in animals.
!    Bisphenol-A. This compound is used to manufacture
polycarbonate, a component in a wide array of plastics and
other polymer products. Bisphenol-A also is used to
manufacture epoxy resins, which are components of a variety
of lacquers and adhesives.
!    Phthalates. Phthalates are one of the most abundant
man-made chemicals in the environment. Phthalate esters are
used in the production of various plastics. Butylbenzyl
phthalate (BBP) also is used in the production of vinyl
floor tiles, adhesives, and synthetic leather.
Di-n-butylphthalate (DBP) is a common plasticizer in
food-packaging materials and polyvinyl chloride. Thousands
of tons of plastics are disposed of annually in landfills,
thus possibly enabling phthalate esters to migrate into soil
and groundwater. These compounds have the ability to
bioconcentrate in animals.
As seen in Chapter 4, other categories of chemicals with ED
characteristics (e.g., heavy metals) are present in wastes
generated by numerous industries.
In conclusion, the evidence that alkylphenols, bisphenol-A,
and phthalates are endocrine disruptors is based mainly on
laboratory studies. The effects of these chemicals on
wildlife populations is not known. Based on the endocrine
disrupting effects of organochlorines on populations of
fish, birds, reptiles, and mammals, however, it is possible
that alkylphenols, bisphenol-A, phthalates, and other
chemicals also could have endocrine disrupting effects in
wildlife. Furthermore, as seen in Chapter 4, it is likely
that some of these chemicals (e.g., the phthalates) are also
components of several non-hazardous industrial wastes.
5.3.5     Red Tides
Red tides are rapid increases in growth (i.e., blooms) of
freshwater and marine plants called dinoflagellates, which
typically are microscopic unicellular organisms that
photosynthesize but also have tails for movement. A red tide
occurs when dinoflagellates multiply rapidly due to optimal
growth conditions such as abundant dissolved nutrients and
sunlight. They produce toxins to defend themselves from
zooplankton and other aquatic grazers. The term red tides
includes orange, brown, red, and even green blooms.
Shellfish, such as clams, mussels, oysters, or scallops,
consume dinoflagellates and can accumulate the toxins in
their flesh. Usually, the shellfish are not severely
affected, but they can contain enough toxins to sicken and
even kill humans. The recently discovered Pfiesteria piscida
is one of many species of dinoflagellate that causes red
tides. It produces potent toxins that cause bleeding sores
in fish and can adversely affect humans via air releases. It
recently has caused massive fish kills in the Neuse and
Pamlico Rivers in North Carolina.
     Several case studies have shown the relationship
between the levels of nutrients, such as phosphorus,
nitrogen, silicon, and iron, in coastal and fresh waters,
and the proliferation of red tides. Studies also have shown
that the high levels of nutrients and eutrophication of the
water (which favors the development of red tides) are often
caused by surrounding human development and industrial and
domestic wastewaters. Recent development of agribusiness and
factory farms in coastal areas releases wastes with high
levels of nutrients into the water that may favor red tides.
     Some researchers believe that the occurrence of red
tides has been increasing over the years, although
improvements in the monitoring and reporting of red tides
could account for this. Even if such an increase were
occurring, however, a commensurate increase in human
poisoning from ingestion of shellfish contaminated with
dinoflagellate toxins has not been seen, likely because of
the improved monitoring and reporting of red tides.
     Notwithstanding the potential link between red tides
and constituents that are often found in non-hazardous
industrial waste, little if any evidence has been found
during this review concerning the degree to which these
wastes may be contributing to the problem. Therefore, for
the purposes of this hazardous waste characteristic gaps
study, EPA does not plan to conduct further research in this
area at this time.
5.3.6     Stratospheric Ozone Depletion
The stratospheric ozone layer protects living organisms from
damaging solar ultraviolet radiation (UV-B). Depletion of
the ozone layer means a greater amount of UV-B radiation is
reaching the earth's surface, which increases human skin
cancers and cataracts, impairs human immune systems, reduces
crop yields, and damages plant and animal life. Several
industrial chemicals, including chlorofluorcarbons (CFCs),
halons, carbon tetrachloride, methyl chloroform, and methyl
bromide, are known to be stratospheric ozone-depleting
substances (ODSs).
For many years, ODSs have been used in a variety of
manufacturing and other activities. With the ratification of
the Montreal Protocol and its subsequent amendments and
adjustments, the United States agreed to eliminate the
production of ODSs by January 1, 1996 (with a few
exceptions). In addition, the disposal of ODSs is tightly
controlled in order to prevent further ozone depletion.
Thus, EPA believes that, for purposes of the hazardous waste
characteristic gaps analysis, ozone-depleting and
non-ozone-depleting risks (e.g., via inhalation during
combustion or from groundwater during land disposal of
residuals) do not need to be examined further at this time.
In a related area (though not necessarily a large-scale
environmental problem), the ultimate elimination of ODSs has
spurred the development of a large number of alternative
chemicals and technologies to replace ODSs. In the United
States, the Significant New Alternatives Policy (SNAP)
Program was put in place by EPA to ensure that alternatives
implemented to replace ODSs are not themselves
environmentally harmful or unsafe for workers and others who
might be exposed to the new chemicals. As part of this
program, EPA has developed a series of SNAP Technical
Background Documents to address the ODS substitutes. Before
a new alternative is developed and introduced into
interstate commerce, EPA must review the alternative and
categorize it as acceptable, acceptable with limitations, or
unacceptable, based on a risk screen of the alternative's
characteristics. This risk screen addresses global
atmospheric effects of the alternative, as well as worker,
consumer, and general population exposure. Thus, groundwater
damage and other more local adverse effects of the
alternative from solid waste generation and management are
included in this screening process. Therefore, EPA does not
intend to conduct further investigations into the solid
waste and hazardous characteristics implications of the
SNAP-approved alternatives at this time.
5.3.7     Tropospheric Ozone and Photochemical Air Pollution
Photochemical reactions between organic chemicals, nitrogen
oxides, and other oxidizing agents can produce ozone and
photochemical oxidant pollution. Such pollution occurs in
areas where sunlight is intense, emissions of nitrogen
oxides and volatile organic compounds (VOCs) are high, and
atmospheric conditions impede regional air circulation. Some
chemicals emitted from non-hazardous industrial waste
management units could contribute to the total emissions of
volatile organics in some locations. As shown in Exhibit
4-2, many potentially reactive VOCs have been found as
constituents of non-hazardous industrial wastes. This
contribution, however, appears to be quite small. Recent
emissions studies have shown that, in most municipal areas
where photochemical pollution is a problem, mobile and
utility sources contribute the largest single portion of
these emissions, with emissions from other sources generally
contributing a smaller amounts. Thus, the Agency did not
pursue this issue further as a potential gap in the
hazardous waste characteristics.
5.3.8     Water Pollution
Based on information reported to EPA by States, Tribes, and
other jurisdictions with water quality responsibilities,
about 40 percent of the Nation's surveyed rivers, lakes, and
estuaries are not clean enough for basic uses such as
fishing or swimming. Polluted runoff from rainstorms and
snowmelt is the leading cause of this impairment. As seen
below, the causes of this damage are highly varied.
!    Rivers. Runoff from agricultural lands is the largest
source of pollution for rivers. Municipal sewage treatment
plants, storm sewers/urban runoff, and resource extraction
also are among the leading sources. Bacteria, which can
cause illnesses in swimmers and others involved in
water-contact sports, are the most common pollutants
impacting rivers. Siltation, nutrients (such as phosphates
and nitrates), oxygen-depleting substances, and metals are
the other leading causes of river pollution.
!    Lakes. As with rivers, runoff from agricultural lands
is the largest source of pollution. Municipal sewage
treatment plants, storm sewers/urban runoff, and unspecified
nonpoint sources also lead the list. Leading causes of lake
pollution are nutrients, siltation, oxygen-depleting
substances, metals, and suspended solids.
!    Estuaries. Storm sewers and urban runoff are the
leading sources of pollution in estuaries. Municipal sewage
treatment plants, agriculture, industrial point sources, and
petroleum activities also lead the list. Nutrients, such as
phosphates and nitrates, are the most often reported
pollutant in estuaries. Other leading causes of pollution
are bacteria, oxygen-depleting substances, and oil and
grease.
Although non-hazardous industrial wastes contribute to this
pollution to some degree (e.g., via sewage treatment and
industrial point and non-point sources), it is unclear
whether this contribution constitutes an actual gap in the
hazardous waste characteristics. For example, significant
changes in EPA's definition of solid waste would be needed
before the hazardous waste characteristics could be used to
prevent some of these wastes from entering surface waters
and resulting in risks or damage. Industrial wastewaters
that are point source discharges subject to regulation under
the Clean Water Act are exempt from the definition of solid
waste. Many of the wastes from agriculture   one of the
largest contributers to water pollution from runoff   are
exempt from the definition of hazardous waste (although they
are solid wastes). Alternatively, EPA could increase
controls on point and non-point sources of water pollution
via other programs. Thus, for purposes of the hazardous
characteristic scoping study, EPA does not plan to research
this area further at this time.
CHAPTER 5. POTENTIAL GAPS ASSOCIATED WITH NATURAL RESOURCE
DAMAGES AND LARGE-SCALE ENVIRONMENTAL PROBLEMS           5-1
5.1  Damage to Groundwater Resources. . . . . . . . . . .5-1
5.2  Damage to Local Air Quality from Odors . . . . . . .5-2
5.3  Large-Scale Environmental Problems . . . . . . . . .5-4
5.3.1     Air Deposition to the Great Waters . . . .5-4
5.3.2     Airborne Particulates. . . . . . . . . . .5-6
5.3.3     Global Climate Change. . . . . . . . . . .5-7
5.3.4     Potential Damages from Endocrine Disruptors  5-9
5.3.5     Red Tides. . . . . . . . . . . . . . . . 5-13
5.3.6     Stratospheric Ozone Depletion. . . . . . 5-14
5.3.7     Tropospheric Ozone and Photochemical Air
          Pollution                               5-15
5.3.8     Water Pollution. . . . . . . . . . . . . 5-15
Exhibit 5-1    Constituents/Properties with SMCLs Found in
               Release Descriptions                   5-2
Exhibit 5-2    Chemicals from Release Descriptions with Low
               Odor Thresholds     5-3
Exhibit 5-3    Initial List of Large-Scale Environmental
               Problems                  5-4
Exhibit 5-4    U.S. Sources of Air Pollutants of Concern for
               Great Waters      5-5
CHAPTER 6. STATE EXPANSIONS OF THE TOXICITY CHARACTERISTIC
           AND LISTINGS
States may adopt hazardous waste regulations that are
broader or more stringent than federal RCRA Subtitle C
regulations. A number of states have done so by regulating
additional wastes as hazardous. For example, states have:
!    Expanded the ignitability, corrosivity, or reactivity
(ICR) characteristics;
!    Expanded the toxicity characteristic (TC);
!    Listed wastes as hazardous that are not hazardous under
the federal rules; and
!    Restricted exemptions from the federal program.
These expansions beyond the federal hazardous waste
identification rules reflect state judgments about gaps in
the federal program and thereby constitute potential gaps
that may merit further investigation.
EPA has identified examples of such expansions by using
readily available information on state hazardous waste
identification rules. In 1992, the EPA Office of Solid Waste, OSW (renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009)
examined state hazardous and non-hazardous industrial waste
programs in 32 states. The study identified "state only"
hazardous wastes, as well as high-risk designations for
non-hazardous wastes. For the purposes of this Scoping
Study, EPA used data from this report and briefly reviewed
current hazardous waste regulations of eight states:
California, Michigan, New Hampshire, Oregon, Rhode Island,
Texas, Washington, and New Jersey.
The first three sections of this chapter address state
expansion of the TC, state only hazardous waste listings,
and state restrictions on exemptions from the federal
regulations, respectively. (State expansions of the ICR
characteristics are addressed in Chapter 3.)  In addition,
Section 6.4 summarizes the findings of the chapter.
6.1  State Expanded Toxicity Characteristics
States have expanded the federal toxicity characteristic by:
!    Adding constituents to the list of TC analytes;
!    Establishing regulatory levels for TC analytes that are
more stringent than federal levels;
!    Specifying alternative tests for identifying toxic
hazardous waste; and
!    Using alternative approaches (other than listing
constituents and regulatory levels) to identify toxic
hazardous wastes.
California, Michigan, and Washington have added constituents
to the list of TC analytes, as shown in Exhibit 6-1. Both
California and Michigan have added zinc, and both California
and Washington have added PCBs. Other additional
constituents include certain metals, pesticides, dioxins,
and potential carcinogens. An example of a state regulatory
level that is lower that the federal TC level is
California's regulatory level of 1.7 mg/l for
pentachlorophenol (versus 100 mg/l under the federal TC).
As discussed in Section 3.6, California requires use of the
Wet Extraction Test (WET) in addition to the TCLP. Use of
the WET test identifies several metal-containing wastes as
hazardous that are generally not identified as hazardous
using the TCLP. These wastes include spent catalysts from
the petroleum refining and food industries and metal dusts,
metal sludges, and baghouse wastes from industries including
fabricated metals, leather and apparel, electric and
electronic products, primary metals, motor vehicles,
transportation equipment, chemicals and allied products, and
others.
     Both California and Washington have established
toxicity criteria for wastes based on acute oral LD50, acute
dermal LD50, acute inhalation LC50, and acute aquatic
96-hour LC50 (see Exhibit 6-2). A waste is designated
hazardous if a representative sample of the waste meets any
of the acute toxicity criteria. For example, Washington
specifies rat and fish (for acute aquatic toxicity) bioassay
tests in a State test methods manual. Generators must either
test a representative sample of the waste or use their
knowledge of waste constituents and the literature regarding
toxicity of those constituents to determine if the waste
meets any of the acute toxicity criteria.
Finally, California's regulations state that a waste
exhibits the characteristic of toxicity if the waste, based
on representative samples, "has shown through experience or
testing to pose a hazard to human health or environment
because of its carcinogenicity, acute toxicity, chronic
toxicity, bioaccumulative properties or persistence in the
environment" (22 CCR 66261.24(a)(8)). This broad provision
tends to shift the burden of identifying toxic wastes to the
generator, because in the absence of specific state criteria
(e.g., constituents and regulatory levels) the generator is
responsible for being aware of experience or tests that show
a waste poses a hazard.
6.2  State Only Listings
In addition to expanded characteristics, some states have
listed state only hazardous wastes. The most common
state-only listed wastes are PCBs and waste oil. At least
four states include additional "F" Wastes; three include
additional "K" wastes; five include additional "P" wastes;
and six include additional "U" wastes. Examples of state
listed wastes include but are not limited to the following:
  !    In California, wastes containing any of almost 800
listed materials are presumed hazardous, unless proven
through testing not to exhibit any of California's criteria
for identifying hazardous waste.
!    Maine has listed certain wastes from the production of
linuron and bromacil, and has listed proposed additions to
the federal list of hazardous wastes.
!    Maryland has listed 9 specific chemical warfare agents.
!    Michigan has added certain chemical production wastes
to its "K" or specific source list, and has listed many
state-only "U" wastes including organics, inorganics in
particle form, pharmaceuticals (e.g., phenobarbital),
chemical warfare agents, and herbicides.
!    New Hampshire has added a number of wastes to its "F"
or non-specific source list, including certain wastes from
industrial painting operations and from metals recovery
operations.
!    Oregon has listed certain pesticide residues and
certain blister agents and nerve gas.
6.3  State Restrictions on Exemptions
Another way that states have expanded the universe of wastes
they regulate as hazardous is by choosing not to adopt
exemptions in the federal regulations. Examples include but
are not limited to the following:     !    Colorado does not
recognize exemptions for certain injected groundwater that
exhibits the TC and is reinjected pursuant to free phase
hydrocarbon recovery operations at petroleum facilities (40
CFR 261.4(b)(11)), certain used chlorofluorocarbon (CFC)
refrigerants that are reclaimed for further use (40 CFR
261.4(b)(12)), or non-terne plated used oil filters (40 CFR
261.4(b)(13)).
!    Connecticut, New Hampshire, Oregon, and Washington do
not include exemptions for certain chromium-bearing wastes
from leather tanning and finishing (40 CFR 261.4(b)(6)(ii)).
!    Maine does not recognize exemptions at 40 CFR
261.4(b)(6) through (13). These include:
--   TC chromium wastes where chromium in the waste is
     nearly exclusively trivalent chromium;
--   certain chromium-bearing wastes from leather tanning
     and finishing;
--   specified mining and mineral processing wastes;
--   cement kiln dust;
--   certain arsenical-treated wood wastes;
--   petroleum contaminated media and debris that fail the
     TC;
--   certain injected groundwater;
--   used CFC refrigerants; and
--   non-terne plated used oil filters.
!    Massachusetts, New York, and North Dakota do not
recognize exemptions at 40 CFR 261.4(b)(10) through (13).
(These wastes include the last four wastes named directly
above.)
6.4  Summary
Some states appear to be regulating a significant number of
wastes as hazardous that are not covered under federal RCRA
regulations. Moreover, a few states have taken different
approaches to identifying characteristic hazardous wastes.
In particular, California and Washington regulations go
beyond constituent-by-constituent definitions and apply
acute toxicity criteria to the whole waste. State expansions
of hazardous waste identification regulations reflect state
judgment about gaps in the federal program. State expansions
have filled these gaps, but only in the specific states with
such expansions. Such potential gaps apparently are not
being filled in the remaining states that have not expanded
the federal hazardous waste definitions.
CHAPTER 6. STATE EXPANSIONS OF THE TOXICITY CHARACTERISTIC
AND LISTINGS6-1
6.1  State Expanded Toxicity Characteristics. . . . . . .6-1
6.2  State Only Listings. . . . . . . . . . . . . . . . .6-2
6.3  State Restrictions on Exemptions . . . . . . . . . .6-5
6.4  Summary. . . . . . . . . . . . . . . . . . . . . . .6-6
Exhibit 6-1    State Toxicity Characteristics:  Additional
               Constituents and More Stringent Regulatory
               Levels                                   6-3
Exhibit 6-2    State Toxicity Criteria Applied to Whole
               Waste (Representative Sample)            6-4
CHAPTER 7. SUMMARY OF POTENTIAL GAPS
This chapter reviews the broad categories of potential gaps
identified in the previous three chapters. Different ways of
organizing the potential gaps are discussed, and a single
comprehensive list of the potential gaps is presented. This
review lays the groundwork for evaluating the significance
of the potential gaps in the following three chapters.
7.1  Organization of the Analysis of Potential Gaps
EPA has identified five categories of potential gaps in the
hazardous waste characteristics using different approaches
in each area:
!    ICR Characteristics. EPA identified potential gaps
associated with these characteristics by reviewing the
original 1980 rulemaking record and comparing the ICR
definitions and test methods to approaches taken to
controlling similar hazards under other federal and state
regulatory schemes.
!    TC Characteristic. The Agency identified potential gaps
associated with this characteristic by examining the
properties of the TC analytes to determine how they could
pose hazards to human health or the environment.
!    Non-TC Chemicals. In contrast with the prior step, EPA
began with a set of properties (including the potential to
appear in non-hazardous industrial wastes) and then
identified individual chemicals and groups of chemicals that
could constitute potential gaps in the characteristics.
!    Natural Resource Damages and Large-scale Environmental
Problems. The Agency examined evidence of possible gaps
using a hybrid approach that considered potential gap
chemicals on the basis of their hazardous properties (e.g.,
endocrine disruption, stratospheric ozone depletion) and
reviewed other potential gaps starting from possible risks
to the environment, which, in turn, implied that certain
waste constituents might be of concern.
!    State Expansion of TC and State Listings. EPA reviewed
how states have expanded their TC and listed as hazardous
certain wastes that are not hazardous under the federal
rules. These expansions reflect state judgments about gaps
in the federal rules and thereby constitute potential gaps
for this Scoping Study.
The potential gaps presented in the following section are
organized primarily by the major categories identified
above. Where appropriate, these categories are subdivided
into groups of chemicals posing similar types of hazards,
and occasionally are subdivided even further by specific
hazardous properties or exposure pathways of concern. Some
of the potential gaps overlap. For example, endocrine
disruptors appear among the concerns associated with the
non-TC analytes as well as in a category by themselves under
large-scale environmental risks. Although this overlap is
inevitable, the potential gaps have been organized so as to
minimize it, without omitting any potentially significant
gaps.
EPA considered other methods of classifying the potential
gaps for purposes of further analysis. Gaps could be
identified, for example, in terms of individual chemicals
and their specific properties and hazards. Alternatively,
the gaps could be organized around groups of chemicals with
specific hazardous properties or types of risks. EPA
rejected these approaches for purposes of this Scoping Study
as impractical because too many individual chemicals or
groups of chemicals, risks, and pathways are involved. In
addition, defining potential gaps in categories that do not
parallel the approaches used to identify such gaps would
make it more difficult to appreciate the evidence and
uncertainty associated with each potential gap.
7.2  Summary of Potential Gaps
Exhibit 7-1 lists the potential gaps in the hazardous waste
characteristics identified by EPA in the preceding chapters.
The individual gaps are organized according to the section
or chapter in which they are discussed, with reference to
specific chemical classes, exposure pathways, or types of
risks, as appropriate. Potent