1. ASTM User Training in Risk-Based Corrective Action for Chemical Releases (Provisional ASTM Standard Guide) Day 1

2. 6/1/99ASTM RBCA for Chemicals User Training 2 Course Objectives u Provide an understanding of the risk-based decision process. u Discuss the importance of Technical Policy Decisions u Emphasize the importance of the development and application of the site conceptual model

3. 6/1/99ASTM RBCA for Chemicals User Training 3 Course Objectives u Provide an understanding of the development of corrective action performance goals and the role of risk assessment and fate and transport in the risk- based decision process u Discuss the issues and processes necessary to make Tier decisions u Discuss the evaluation and selection of remedial action options

4. 6/1/99ASTM RBCA for Chemicals User Training 4 Course Expectations u Elementary understanding of the basic science necessary to make risk-based decisions u Understanding of the concepts and process necessary to implement a framework for making risk-based decisions u Understanding of the applicability of the RBCA framework to a variety of sites u Understanding of the issues related to the integration of the RBCA framework into an existing regulatory program

5. 6/1/99ASTM RBCA for Chemicals User Training 5 Course Expectations u This course is NOT intended to provide specific applications to existing regulatory programs u This course is NOT intended to provide all the tools necessary to perform risk-based decisions

6. 6/1/99ASTM RBCA for Chemicals User Training 6 – 8:00 - 8:30Introduction – 8:30 - 9:30Summarizing the Framework – 9:30 - 9:45Break – 9:45 - 10:45Summarizing the Framework – 10:45 - 11:00Break – 11:00 -12:00Technical Policy Decisions – 12:00 - 1:00Lunch – 1:00 - 2:15Technical Policy Decisions – 2:15 - 2:30Break – 2:30 - 4:00Developing the Site Conceptual Model – 4:00 - 4:15Break – 4:15 - 5:00Developing the Site Conceptual Model Agenda: Day 1

7. 6/1/99ASTM RBCA for Chemicals User Training 7 Agenda - Day 2 – 8:00 - 9:30RBSL/SSTL Development – 9:30 - 9:45Break – 9:45 - 10:45RBSL/ SSTL Development – 10:45 - 11:00Break – 11:00 -12:00RESC/SSEC Development/Data Collection – 12:00 - 1:00Lunch – 1:00 - 2:30Tier Decisions/Remedial Options – 2:30 - 2:45Break – 2:45 - 4:00Source Reduction/ Activity and Land Use Controls – 4:00 - 4:15Break – 4:15 - 5:00Factors for Consideration in Remedial Action Selection

8. 6/1/99ASTM RBCA for Chemicals User Training 8 ASTM “standards” are developed through a rigorous consensus- building process, that may also include external peer review (as in the case of RBCA). Members vote to approve standards, and all negative ballots must be resolved. ASTM is an organization that has historically focused on promulgating standards for engineering tests and specifications for engineering materials. Who is ASTM?

9. 6/1/99ASTM RBCA for Chemicals User Training 9 ASTM RBCA Authored by a multi-functional and multi-disciplinary group of ASTM E-50 Subcommittee members, representing: ASTM “RBCA” u State Regulators u USEPA Staff u Insurance Industry u Banking Industry u Chemical Industry u Oil Industry u Academia u Consulting u Reimbursement Fund Managers u Regulatory Managers u Hydrogeologists u Toxicologists u Environmental Engineers u Environmental Scientists u Modelers

10. 6/1/99ASTM RBCA for Chemicals User Training 10 RBCA is a framework developed by ASTM in which exposure and risk assessment practices are integrated with traditional components of the corrective action process. RBCA Goals:  protection of human health and environment  consistent and technically-defensible decisions  selection of appropriate and resource-efficient remedies  optimal allocation of limited resources  practical and resource-efficient approach  achievement of corrective action and redevelopment together Risk-Based Corrective Action (RBCA) Process

11. 6/1/99ASTM RBCA for Chemicals User Training 11 Why 3 Tiers (Levels) in RBCA? Tier 1 Tier 3 Target Risk Every tier achieves the same level of public health protection Tier 2 Less Site-Specific Uncertainty Greater Site-Specific Effort

12. 6/1/99ASTM RBCA for Chemicals User Training 12 Technical Policy Decisions RBCA Framework Regulatory Program How is a RBCA Program Developed? ASTM Risk-Based Corrective Action for Chemical Release Sites – outlines a framework for integrating exposure and risk assessment practices with traditional components of the corrective action process. – describes steps and philosophy to build the framework and to incorporate technical policy decisions into corrective action programs. – identifies stakeholders and stakeholder involvement in the program development

13. 6/1/99ASTM RBCA for Chemicals User Training 13 RBCA Framework Regulatory Program Technical Policy Decisions How is a RBCA Program Implemented? u ASTM Risk-Based Corrective Action for Chemical Release Sites – provides mechanism for stakeholder involvement – makes technical policy decisions – integrates framework into regulatory program – provides training for stakeholders

14. 6/1/99ASTM RBCA for Chemicals User Training 14 Policy RBCA Customization: Technical Policy Decisions u Target risk limits u Land use issues u Ground water use issues u Chemical(s) of concern u Data requirements u Site classification procedures u Exposure assumptions and pathways u Point(s) of demonstration u Fate and transport – natural attenuation – modeling procedures u Remedy selection criteria u Interim remedial action u Institutional controls u Engineering controls u mass reduction vs. risk reduction u Stakeholder involvement

15. Summarizing the Framework

16. Definitions

17. 6/1/99ASTM RBCA for Chemicals User Training 17 Definitions u The Corrective Action Process – the sequence of actions that include site assessment and investigation, interim remedial action, remedial action, operation and maintenance of equipment, monitoring of progress, and termination of the remedial action. – Chemical Release – any spill or leak or detection of concentrations of chemical(s) of concern in environmental media

18. 6/1/99ASTM RBCA for Chemicals User Training 18 Risk Toxicity & Exposure Exposure Concentration & Intake Definitions u Risk Assessment – an analysis of the potential for adverse effects on receptors and relevant ecological receptors and habitats caused by a chemical(s) of concern from a site – the basis for the development of corrective action goals and determination of the need for interim remedial action, remedial action or a combination of these actions

19. 6/1/99ASTM RBCA for Chemicals User Training 19 Definitions u Technical Policy Decisions – the choices specific to the user that are necessary to implement the Risk-Based Corrective Action framework involve professional judgment to evaluate available data may be more then one scientifically supportable answer the choices represent different approaches appropriate technical policy decisions may have already been made by the regulatory agency – Examples of technical policy decisions: data quality objectives, target risk levels, land use, ground water use, natural resource protection, relevant ecological receptors and habitats and exposure

20. 6/1/99ASTM RBCA for Chemicals User Training 20 Definitions u Chemical(s) of Concern (CoCs) – specific constituents and their breakdown products that are identified for evaluation identification can be based on their historical and current use at a site, detected concentrations in environmental media and their mobility, toxicity, and persistence in the environment

21. 6/1/99ASTM RBCA for Chemicals User Training 21 Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 ASTM Risk- Based Corrective Action (RBCA) Fl owchart Yes No Initial Response Classification & Risk Reduction Tier 1 Evaluation Initial Site Assessment Decision Point? Interim Remedial Action Yes No Tier 2 Evaluation No Yes Tier 3 Evaluation Yes No Yes Remedial Action Program Monitoring No Further Action No Yes No Decision Point?

22. 6/1/99ASTM RBCA for Chemicals User Training 22 Step 1 Initial Site Assessment u Identify all available information concerning – nature of the release – physical condition and setting of the site – environmental condition of the site u Focus on developing the site conceptual model – identifying incomplete exposure pathways u Determine if further action is necessary

23. 6/1/99ASTM RBCA for Chemicals User Training 23 Step 1 Initial Site Assessment u Non-intrusive and intrusive data collection activity to support – initial response action evaluation – risk reduction activities – refinement of site conceptual model – comparison of concentrations of chemical(s) of concern in environmental media to risk-based screening levels (RBSL) – comparison of site conditions to relevant ecological screening criteria (RESC)

24. 6/1/99ASTM RBCA for Chemicals User Training 24 Step 2 Risk Initial Response Action Initial Response Action & Risk Reduction Risk Reduction Activity

25. 6/1/99ASTM RBCA for Chemicals User Training 25 Site Off-Site Residual Phase Source Area Free Phase Dissolved Phase Free Phase Vapor Phase Source Area(s) - the location of non-aqueous phase liquid (NAPL) chemical, the locations of highest soil or ground water concentrations of the chemical(s) of concern or the location releasing the chemical(s) of concern Step 1 Initial Site Assessment Source(s) and Source Area(s)

26. 6/1/99ASTM RBCA for Chemicals User Training 26 Step 1 Atmospheric fate & transport deposition Site Soil to Ground Water Soil to air Ground Water to Air Ground Water Transport Runoff Dust to air Off-Site Initial Site Assessment Transport Mechanisms Chemical(s) of concern dissolved in ground water

27. 6/1/99ASTM RBCA for Chemicals User Training 27 Initial Site Assessment Receptors Site Off-Site Receptors Step 1 Industrial land useFuture land use ?Residential land use

28. 6/1/99ASTM RBCA for Chemicals User Training 28 Initial Site Assessment Relevant Ecological Receptors and Habitats u Ecological resources that are to be protected are – communities with threatened and endangered species – recreationally or commercially important communities – that are regionally or nationally rare – communities with high aesthetic quality – communities that afforded special protection by law or regulation – habitats that support these communities. u Identification may come from applicable federal and state regulations Step 1

29. 6/1/99ASTM RBCA for Chemicals User Training 29 Point(s) of Exposure - The point(s) at which an individual or population may come in contact with a chemical(s) of concern originating from a site. Step 1 Site Point(s) of Exposure Off-Site Initial Site Assessment Point(s) of Exposure

30. 6/1/99ASTM RBCA for Chemicals User Training 30 Tier 1 Evaluation Exposure Pathway Receptor Source Area Transport Mechanism Step 3 Exposure Pathway - describes a mechanism by which an individual or population is exposed to a chemical(s) of concern and includes a source or source area, a transport/exposure medium (e.g., air or water), a point of exposure, and an exposure route.

31. 6/1/99ASTM RBCA for Chemicals User Training 31 Site Conceptual Model - The integrated representation of the physical and environmental context, the complete and potentially complete exposure pathways and the likely distribution of chemical(s) of concern at a site Leaching and Ground Water Transport Leaching and Ground Water Transport Wind Erosion and Atmospheric Dispersion Wind Erosion and Atmospheric Dispersion oResidential oCommercial/Industrial oConstruction worker oSensitive habitat PRIMARY SOURCES SECONDARY SOURCES EXPOSURE ROUTES RECEPTORS TRANSPORT MECHANISMS Affected Subsurface Soils (>3 ft depth) Affected Subsurface Soils (>3 ft depth) Stormwater/ Surface Water Transport Stormwater/ Surface Water Transport SURFACE WATER Recreational Use/ Sensitive Habitat SURFACE WATER Recreational Use/ Sensitive Habitat Volatilization and Atmospheric Dispersion Volatilization and Atmospheric Dispersion Ground Water Potable Water Use Process Water Use AIR Inhalation of Vapor or Particulates AIR Inhalation of Vapor or Particulates SOIL Dermal Contact or Ingestion SOIL Dermal Contact or Ingestion qProduct Storage qPiping / Distribution qOperations qWaste Management qUnit qOther qProduct Storage qPiping / Distribution qOperations qWaste Management qUnit qOther Volatilization and Enclosed Space Accumulation Volatilization and Enclosed Space Accumulation Mobile Free Liquid Migration Mobile Free Liquid Migration Dissolved Ground Water Plume Dissolved Ground Water Plume Affected Surface Soils, Sediments or Surface Water Affected Surface Soils, Sediments or Surface Water Free- Phase Liquid Plume Free- Phase Liquid Plume Affected Surface Soils (<3 ft depth) Affected Surface Soils (<3 ft depth) oResidential oCommercial/Industrial oConstruction worker oResidential oCommercial/Industrial oResidential oRecreational oSensitive habitat Step 3 Site Conceptual Model

32. 6/1/99ASTM RBCA for Chemicals User Training 32 Step 3 Risk-Based Screening Levels (RBSL) u Represent concentrations that satisfy the criteria for Not Further Action at Tier 1 – RBSL typically quantitative u Use conservative values for risk and exposure assumptions u May use regulatory values – MCL, aesthetic values (taste or odor)

33. 6/1/99ASTM RBCA for Chemicals User Training 33 Ecological issues within the RBCA process u RBCA framework can be used to evaluate ecological risk u Ecological risk can follow a tiered process u PS-104 provides guidance on how to get started u Specific guidance is under development u Responses tend to be evaluated for populations/ecosystems, rather than individuals u Guidelines for Ecological Risk Assessment EPA/630/R-95/002F, 4/98, Final Step 3

34. 6/1/99ASTM RBCA for Chemicals User Training 34 Relevant Ecological Screening Criteria (RESC) u Non-site-specific u Used in the Initial Site Assessment and Tier 1 evacuation u Part of the technical policy decisions u Can be qualitative or quantitative in nature – qualitative - waterfowl feeding and nesting – quantitative - water quality criteria u Can be based on concentrations of chemical(s) of concern or biological measures Step 3

35. 6/1/99ASTM RBCA for Chemicals User Training 35 Site Off-Site Tier 1 Evaluation Risk-Based Screening Levels C RBSL Point(s) of exposure is assumed to be located proximal to the source area(s)  Compare highest concentrations of chemical(s) of concern to RBSL for complete and potentially complete exposure pathways  Compare site conditions to RESC Step 3

36. 6/1/99ASTM RBCA for Chemicals User Training 36 Tier 1 Decisions Factors u The basis for the RBSL or RESC are not representative of the site-specific conditions – hydrogeology, exposure parameters, point(s) of exposure, reasonable land use options u The RBSL or RESC do not exist for a complete and potentially complete exposure pathway u An unacceptable risk to a relevant ecological receptor or habitat is identified during the Tier 1 qualitative ecological screening evaluation Step 4

37. 6/1/99ASTM RBCA for Chemicals User Training 37 Tier 1 Decisions Factors u Site-specific target levels (SSTL) or site-specific ecological criteria (SSEC) developed under further tier evaluation will be significantly different than the RBSL or RESC or will significantly modify the remedial action activities u The cost of remedial action based on RBSL will likely be greater than further tier evaluation and subsequent remedial action. Step 4

38. 6/1/99ASTM RBCA for Chemicals User Training 38 Tier 1 Outcomes u No further action – if the concentrations of the chemical(s) of concern are below the RBSL – if the comparison of the site conditions to RESC indicate that there is no unacceptable risk to relevant ecological receptors and habitats u Compliance monitoring – not confident that data support the conclusion that concentrations will not be above RBSL in the future – to collect data sufficient to confidently conclude that concentrations will not be above RBSL in the future. Step 4

39. 6/1/99ASTM RBCA for Chemicals User Training 39 Tier 1 Outcomes u Interim remedial action – address most significant concerns in an expedited fashion u Remedial action – reduce concentrations of chemical(s) of concern at the point(s) of exposure – eliminate a complete or potentially exposure pathway – address an unacceptable risk Step 4

40. 6/1/99ASTM RBCA for Chemicals User Training 40 Tier 1 Outcomes u Further Tier evaluation – complete and potentially complete exposure pathways with concentrations of chemical(s) of concern above RBSL or do not meet RESC – maintains the same level of protectiveness, but uses site specific data to help make better informed decisions. Step 4

41. 6/1/99ASTM RBCA for Chemicals User Training 41 Tier 2 SSTL Step 5 u Develop SSTL using RBSL methods, but replace default assumptions with site-specific parameters – compare to concentrations of chemical(s) of concern in the source area(s) u Develop statistical representation of source area concentrations of chemical(s) of concern when appropriate data exist – compare to RBSL or SSTL developed by using site- specific parameters

42. 6/1/99ASTM RBCA for Chemicals User Training 42 Tier 2 SSTL and SSEC u Develop SSTL by applying RBSL at point(s) of exposure and back-calculating SSTL for chemical(s) of concern at source area(s) – evaluate fate and transport of chemical(s) of concern in environmental media – based on estimated, measured, or monitored attenuation u Develop SSEC for relevant ecological receptors and habitats based on additional qualitative or quantitative analyses Step 5

43. 6/1/99ASTM RBCA for Chemicals User Training 43 Example Tier 2 Evaluation u Substituting site-specific parameters in RBSL method Step 5 C GW C W  1 1  V  GW IW W=source width parallel to ground water flow [m]  GW =thickness of ground water mixing zone [m] I= infiltration rate [m/y] V=ground water flow velocity [m/y] C W =dissolved concentration in vadose zone source area [mg/l] C GW =dissolved concentration in ground water source area [mg/l] W I V  GW CWCW

44. 6/1/99ASTM RBCA for Chemicals User Training 44 Example Tier 2 Evaluation u Statistical representation of source area concentrations Step 5

45. 6/1/99ASTM RBCA for Chemicals User Training 45 Site Off-Site C poe C soil C gw Example Tier 2 Evaluation Site-Specific Target Level Applied at Source Area RBSL Applied at Point of Exposure Source Area Step 5 u Back-calculating SSTL at source area(s) by applying RBSL at point of exposure

46. 6/1/99ASTM RBCA for Chemicals User Training 46 Example Tier 2 Evaluation u Back-calculating SSTL at source area(s) by applying RBSL at point of exposure Step 5 C gw (x) = C  f ( degradation, seepage velocity, thickness of source zone, dispersion ) C gw = chemical of concern along centerline of the plume C   steady state source concentration

47. 6/1/99ASTM RBCA for Chemicals User Training 47 Example Tier 2 Evaluation u Tier 2 site-specific ecological criteria (SSEC) – used in Tier 2 evaluations – usually quantitative in nature – part of technical policy decisions – Tier 2 refines Tier 1 RESC with more site-specific parameters refine a model by using site-specific soil characteristics use a toxicity value that is more appropriate for a relevant ecological receptor or habitat at the site Step 5

48. 6/1/99ASTM RBCA for Chemicals User Training 48 Site Off-Site C poe C soil C gw Tier 2 - Point(s) of Demonstration Source Area Step 5 Point(s) of Demonstration - A location(s) selected between the source area(s) and the potential point(s) of exposure where concentrations of chemical(s) of concern must be at or below the determined target levels in media (e.g., ground water, soil or air). C pod

49. 6/1/99ASTM RBCA for Chemicals User Training 49 Step 6 Tier 2 Decisions Factors u The basis for the SSTL or SSEC are not representative of the site-specific conditions – hydrogeology, exposure parameters, point(s) of exposure, reasonable land use options u The SSTL or SSEC do not exist for a complete and potentially complete exposure pathway u An unacceptable risk to a relevant ecological receptor or habitat is identified during the Tier 2 comparison to SSEC

50. 6/1/99ASTM RBCA for Chemicals User Training 50 Step 6 Tier 2 Decisions Factors u Site-specific target levels SSTL or SSEC developed under further tier evaluation will be significantly different than the SSTL or SSEC or will significantly modify the remedial action activities u The cost of remedial action based on SSTL will likely be greater than further tier evaluation and subsequent remedial action.

51. 6/1/99ASTM RBCA for Chemicals User Training 51 Step 6 Tier 2 Outcomes u No further action – if the concentrations of the chemical(s) of concern are below the SSTL – if the comparison of the site conditions to SSEC indicate that there is no unacceptable risk to relevant ecological receptors and habitats u Interim remedial action – address most significant concerns in an expedited fashion

52. 6/1/99ASTM RBCA for Chemicals User Training 52 Step 6 Tier 2 Outcomes u Remedial action – reduce concentrations of chemical(s) of concern at the point(s) of exposure – eliminate a complete or potentially exposure pathway – address an unacceptable risk u Further Tier evaluation – complete and potentially complete exposure pathways with concentrations of chemical(s) of concern above SSTL or do not meet SSEC – maintains the same level of protectiveness, but uses site specific data to help make better informed decisions.

53. 6/1/99ASTM RBCA for Chemicals User Training 53 Step 7 Tier 3 SSTL and SSEC u Tier 3 involves the highest level of sophistication and resources – the development and use of site-specific numerical models – use of probabilistic data representations – address variability and uncertainty – development of site-specific exposure factors, exposure scenarios, toxicity data, bioavailability, and biomagnification u Requires significantly more detailed site-specific data collection

54. 6/1/99ASTM RBCA for Chemicals User Training 54 Step 7 Example Tier 3 Evaluation u Uncertainty and Probabilistic Analysis – Uncertainty represents ignorance or lack of perfect knowledge about poorly characterized phenomena or models addressed in Tier 1 by conservative assumptions addressed in Tier 2 by site-specific measurements addressed in Tier 3 by better measurements or probabilistic analysis – Probabalistic analysis is the use of distributions of input values

55. 6/1/99ASTM RBCA for Chemicals User Training 55 Step 7 Example Tier 3 Evaluation u Bioavailability, biodegradation and biomagnification – bioavailability is a measure of the fraction of the chemical(s) of concern in environmental media that is accessible to an organism for absorption – biodegradation is natural plant, animal or microbial metabolism that results in the reduction of mass of chemical(s) of concern – biomagnification a measure of the fraction of chemical(s) of concern that transfer and accumulate in a organism as a result of food web consumption

56. 6/1/99ASTM RBCA for Chemicals User Training 56 Step 7 Example Tier 3 Evaluation u Tier 3 site-specific ecological criteria – used in Tier 3 evaluations – usually quantitative in nature – part of technical policy decisions – Tier 3 completely site-specific and refines Tier 2 SSEC use a toxicity value that is more appropriate for a relevant ecological receptor – can involve lab toxicity studies applicable to ecological exposure e.g., round worm exposure tests in soil

57. 6/1/99ASTM RBCA for Chemicals User Training 57 Step 8 Tier 3 Outcomes u No further action – if the concentrations of the chemical(s) of concern are below the SSTL – if the comparison of the site conditions to SSEC indicate that there is no unacceptable risk to relevant ecological receptors and habitats u Interim remedial action – address most significant concerns in an expedited fashion

58. 6/1/99ASTM RBCA for Chemicals User Training 58 Step 8 Tier 3 Outcomes u Remedial action – reduce concentrations of chemical(s) of concern at the point(s) of exposure – eliminate a complete or potentially exposure pathway – address an unacceptable risk

59. 6/1/99ASTM RBCA for Chemicals User Training 59 Step 9 Remedial Action Option Evaluation u Effectiveness of the remedial action in protecting human health and the environment, u Long-term reliability and probable success in meeting the remedial action goals now and in the future, u Short-term risks posed by the implementation of the remedial action, u Amenability of the remedial action to integration with property redevelopment plans,

60. 6/1/99ASTM RBCA for Chemicals User Training 60 Step 9 Remedial Action Option Evaluation u Acceptability of the remedial action to the stakeholders, u Implementability and technical practicability of the remedial action, and u The cost-effectiveness of the options to meet the remedial action goals.

61. 6/1/99ASTM RBCA for Chemicals User Training 61 Remedial Action Plan u Based on the appropriate RBSL, SSTL, RESC, SSEC or remedial action goals, source area(s) and point(s) of exposure, choose measures to achieve the corrective action goals or eliminate exposure pathways u Remedial options may include combinations of active and passive measures Considerations: u source removal or reduction u eliminate exposure u natural attenuation u engineering controls u institutional controls Weight of considerations are based on a technical policy decision Step 9

62. 6/1/99ASTM RBCA for Chemicals User Training 62 Step 10 Monitoring Program u Following, or during remedial action, a monitoring plan is needed to insure that the appropriate RBSL, SSTL, RESC, SSEC or remedial action goals established in the Tier analysis continue to be met u Verify assumptions and predictions used in Tier 2 and Tier 3.

63. 6/1/99ASTM RBCA for Chemicals User Training 63 “No Further Action” and Conditions of Closure u Ease of obtaining an NFA is related to confidence in supporting data and requirements of the governing regulatory framework u Example NFA letter contents – reservation of rights / re-opener clauses – monitoring requirements demonstrate the effectiveness of implemented remedial action confirm that current conditions persist or will improve with time – maintenance requirements ensure integrity and continued performance – financial responsibility provisions Step 10

64. Technical Policy Decisions RBCA: How to Implement a Program

65. 6/1/99ASTM RBCA for Chemicals User Training 65 Technical Policy Decisions u Assumptions and values used in the risk-based decision process to ensure that decisions are protective of human health and the environment – “set the floor” – made “up front” – performance-based acceptable levels of conservatism and uncertainty – involve professional judgment – more than one scientifically supportable answer possible – include social, economic and other considerations

66. 6/1/99ASTM RBCA for Chemicals User Training 66 Technical Policy Decisions Technical and Policy Decisions Political and Social Economic Scientific Regulatory Driven Decisions made as part of a regulatory program that apply to all sites or a set of circumstances Site Driven Decisions made at an individual site based on site-specific circumstances Business Driven Decisions made at an individual site based on business-specific circumstances

67. 6/1/99ASTM RBCA for Chemicals User Training 67 Topics u Identify some of the more controversial topics – stakeholder involvement – ground water resource and use – point(s) of demonstration – uncertainty and conservatism – data quantity and quality objectives – adequacy of site assessment – target risk and hazard quotient – activity and land use – ecological risk

68. 6/1/99ASTM RBCA for Chemicals User Training 68 Stakeholder Involvement u Who are they? u When do they get involved? u How should they be involved? – regulatory program development – site-specific decisions – informational

69. 6/1/99ASTM RBCA for Chemicals User Training 69 Stakeholder Involvement Who are They? u Regulatory agency u Owners u Community u Real estate interests u Financing interests u State and local government u Environmental groups

70. 6/1/99ASTM RBCA for Chemicals User Training 70 Stakeholder Involvement Program Element u Many state and federal programs develop regulations, policies and guidelines with specific consensus building requirements and formal or informal requirements for representation by balanced stakeholder groups. u It is extremely important for the program development process to consider the use of such representation to reach consensus on some of the widely debated issues which could impact the application and implementation of the RBCA process.

71. 6/1/99ASTM RBCA for Chemicals User Training 71 Stakeholder Involvement Site-Specific Element u The level of site-specific involvement will depend on the type and severity of the situation – land and activity use decisions – impact to surrounding areas – community concerns

72. 6/1/99ASTM RBCA for Chemicals User Training 72 Stakeholder Involvement Informational u Constructive dialog that acknowledges the needs and expectations of the stakeholders u Education and outreach u Identify stakeholder concerns on potential corrective action

73. 6/1/99ASTM RBCA for Chemicals User Training 73 Class Exercise # ?? Site-Specific Stakeholder Involvement u A truck spills 20 gallons of diesel fuel on the interstate highway – who to tell? – who to ask?

74. 6/1/99ASTM RBCA for Chemicals User Training 74 Class Exercise # ?? Site-Specific Stakeholder Involvement u How about this stuff? – bottles of discarded ant poison, circa 1930s – suburban residential neighborhood.

75. 6/1/99ASTM RBCA for Chemicals User Training 75 Corrective Action Goals u What are the appropriate goals for corrective action? – background – analytical detection limits – generic standards – technical impracticability – financial impracticability – site-specific risk-based – environmentally acceptable endpoints

76. 6/1/99ASTM RBCA for Chemicals User Training 76 Chemical(s) of Concern u What is the criteria for selection of chemical(s) of concern and indicator chemicals? – all chemicals based on analytical detection – specific chemicals based on knowledge of material released

77. 6/1/99ASTM RBCA for Chemicals User Training 77 Decision Criteria u What criteria should be considered when making decisions? – timing – long and short term reliability – implementability – costs – acceptability to stakeholders – others?

78. 6/1/99ASTM RBCA for Chemicals User Training 78 Fate and Transport u What criteria should be used to select models to predict fate and transport of a chemical? – model performance-based – strict list of acceptable models

79. 6/1/99ASTM RBCA for Chemicals User Training 79 Exposure Pathways u What is the process for identifying exposure pathways and receptors for consideration and the criteria for exclusion or elimination of an exposure pathway? – documentation and tracking requirements – hierarchy of land use and resource use criteria

80. 6/1/99ASTM RBCA for Chemicals User Training 80 Technical Policy Decision Ground Water Resources and Use u What criteria should be used to determine the need and extent for restoration of ground water and beneficial resources? – drinking water everywhere and always – current and potential future use determination – classification of ground water yield rates quality (e.g. presence of salt water or nitrates) hydrogeologic considerations - barriers and confining layers ecosystem impacts, surface water connection natural resource value

81. 6/1/99ASTM RBCA for Chemicals User Training 81 Technical Policy Decision Ground Water Resources and Use u What criteria should be used to determine the need and extent for restoration of ground water and beneficial resources? u Classification of ground water is a technical policy decision u Classification decisions may consider: – yield rates – quality (e.g. presence of salt water or nitrates) – hydrogeologic considerations - barriers and confining layers

82. 6/1/99ASTM RBCA for Chemicals User Training 82 Future Use of Groundwater u Drinking water everywhere and always u Other extreme: never any water use anywhere. u Consensus on this issue is important to implement RBCA

83. 6/1/99ASTM RBCA for Chemicals User Training 83 Consensus u What is the most effective compromise on groundwater issues which best balances social, scientific and financial concerns? u Examples: time (natural attenuation) or location (off-site plume) exceptions to DW.

84. 6/1/99ASTM RBCA for Chemicals User Training 84 Class Exercise # ?? u Rural area on growing suburban fringe and no municipal drinking water supply

85. 6/1/99ASTM RBCA for Chemicals User Training 85 Class Exercise # ?? u RCRA facility with municipal drinking water supply and river greater then 3 miles from the facility

86. 6/1/99ASTM RBCA for Chemicals User Training 86 Summary of Ground Water Resources and Use Issues u How did you come to a decision in your group? u What did you decide and why? u Did you consider drinking water as well as agricultural uses? u Did you provide for exceptions to your classification scheme?

87. 6/1/99ASTM RBCA for Chemicals User Training 87 Point of Demonstration for Chemicals in the Ground Water u Where should the point(s) of demonstration be located? – at the property line? – at points defined by regulation – at site-specific determined point(s) of exposure? – different application for current potential exposures and future potential exposures – at the point of access for water uses?

88. 6/1/99ASTM RBCA for Chemicals User Training 88 Point of Demonstration for Chemicals in the Ground Water u How should travel time be accounted for? u What are the contingency ways to prevent contact with a receptor? u What soil and bedrock characteristics will contribute to natural attenuation?

89. 6/1/99ASTM RBCA for Chemicals User Training 89 High Uncertainty & Conservatism Low Uncertainty & Conservatism Tier 3 Tier I Uncertainty u How should uncertainty be addressed? – better measurements – conservative assumptions – probabilistic analyses u This issue exists in many endeavors. u Learn how to manage uncertainty early on in the RBCA Process

90. 6/1/99ASTM RBCA for Chemicals User Training 90 Managing Uncertainty u How will Data be Used? – physical, chemical and hydrogeolocical data u What quantity and quality of data is required? – indicators and screening – confirmatory and detailed site-specific – practical quantitation limits. – minimum number of samples – the safety net – the statistical approach.

91. 6/1/99ASTM RBCA for Chemicals User Training 91 Managing Uncertainty u Better measurements needed to address both: – variability (true heterogenuity in a well-characterized phenomenon, cannot be reduced by further measurements) and – uncertainty (ignorance about a poorly characterized phenomenon that can be reduced through further measurements).

92. 6/1/99ASTM RBCA for Chemicals User Training 92 Managing Uncertainty u Uncertainty can be addressed by better measurements or by making conservative assumptions. u The effect of conservative assumptions is to: – overestimate mass – overestimate concentrations at the point(s) of exposure – overestimate resulting doses – overestimate health effects

93. 6/1/99ASTM RBCA for Chemicals User Training 93 Managing Uncertainty u Conservatism assumptions may result in an overestimate of: – mass of chemical(s) of concern – concentrations at the point(s) of exposure – doses to receptors – health effects on receptors

94. 6/1/99ASTM RBCA for Chemicals User Training 94 Cancer and Non-Cancer Risk u What is the appropriate target risk and how should cumulative and additive effects be treated? – used to calculate screening levels and site-specific levels – cancer individual chemical cumulative of all carcinogenic chemicals – non-cancer individual chemical additive of all non-carcinogenic chemicals

95. 6/1/99ASTM RBCA for Chemicals User Training 95 Cancer Risk Target Risk Levels u USEPA excess lifetime cancer risk range – EPA’s guidance (OSWER Directive 9355.0-30) Where cumulative carcinogenic site risk to an individual based on reasonable maximum exposure for both current and future land use is less than 10-4, action is generally not warranted. Action may be taken at less than 10-4 based on site-specific concerns, but all records of decisions for remedial actions taken at sites posing risks within 10-4 to 10-6 must explain why remedial action is warranted.

96. 6/1/99ASTM RBCA for Chemicals User Training 96 Background Risk: Existing risk of cancer incidence. Excess Risk: Additional risk of cancer incidence due to exposure to site constituents. Background Cancer Risk Excess Risk LimitTotal Risk 0.251.0E-60.250001 0.25 1.0E-50.25001 0.250.2501 1.0E-4 Cancer Risk Excess vs. Total Cancer Risk

97. 6/1/99ASTM RBCA for Chemicals User Training 97 Cumulative Cancer Risks Example u Massachusetts has a significant risk definition of 1 X 10 -5 for total site cancer risk. – Method 1 Tables and Method 2 formulas are based on a 1X10 -6 for individual chemicals where there are no more than 10 chemicals. – Method 3 total site risk may not exceed 1 X 10 -5 u Texas Risk Reduction Program – has a significant risk definition of 1 X 10 -5 for individual chemicals – requires a cumulative adjustment to 1 X 10 -5 where there are more then 10 chemicals

98. 6/1/99ASTM RBCA for Chemicals User Training 98 Non-Cancer Hazard Quotient u Quantifying non-cancer effects – evaluated by comparing the estimated dose with a reference dose – ratio is called the Hazard Quotient – a Hazard Quotient of less than one is typically considered to be of no concern.

99. 6/1/99ASTM RBCA for Chemicals User Training 99 = Risk for a single chemical in Tier 1 = Risk of all chemicals in Tier 3 Additive Non- Cancer Risks Example

100. 6/1/99ASTM RBCA for Chemicals User Training 100 Adequacy of Site Assessment u How much site assessment is necessary? – Command and Control approach: the full vertical horizontal extent of contamination. – The prescriptive approach: three groundwater wells, 10 foot grids and thousands of soil samples. – The compromise: Data quality objectives and how the data will be used. – Safety net issues.

101. 6/1/99ASTM RBCA for Chemicals User Training 101 Data Quantity and Quality u What quantity and quality of data is appropriate to make corrective action decisions? – how will data be used? indicators and screening confirmatory and detailed site-specific statistical representations fate and transport modeling – what type of data is needed physical, chemical and hydrogeological data

102. 6/1/99ASTM RBCA for Chemicals User Training 102 Activity and Land Use u How can land and activity uses other than residential land use be established for a property? – how to define residential, commercial, industrial or other activities – use of institutional controls u How effective are land and activity use controls in ensuring that future users will not be adversely affected if chemical(s) of concern remain at a site? – long term effectiveness and reliability of control – effects of current and future exposures to releases

103. 6/1/99ASTM RBCA for Chemicals User Training 103 Identification and selection of relevant ecological receptors and habitats u General versus specific receptors – example: general - a surface water resource passing through a region specific - a bald eagle in the wetlands adjacent to a site – could also include habitats – need to consider receptors/habitats and complete exposure pathways – what decision criteria will be used for the selection?

104. 6/1/99ASTM RBCA for Chemicals User Training 104 Identification and selection of relevant ecological receptors and habitats u Societal versus scientific value – public perception does not always equate to ecological health a recreational water body is devoid of fish and water fowl because the sediments supporting higher levels of aquatic life are non-existent society looks at the recreational fish and aesthetics of the water fowl – scientists looks at the worms

105. 6/1/99ASTM RBCA for Chemicals User Training 105 Identification and selection of relevant ecological receptors and habitats u Individual versus a population/community – individual considered only when rare, threatened or endangered species are involved – population/community is usually what is considered

106. 6/1/99ASTM RBCA for Chemicals User Training 106 Identification and selection of relevant ecological receptors and habitats u Ecological risk assessment – utilize entry/exclusion criteria as relevant ecological screening criteria (RESC) size of site or of population impacted experience base and characteristics of the site u The process is parallel but much more complicated than for human health u Extensive problem formulation and regulatory discussions required u Re-evaluation is needed with new information

107. 6/1/99ASTM RBCA for Chemicals User Training 107 Wrap up u We have learned why the key technical policy decisions are important. u The decisions must be dynamic, not carved in stone and be flexible enough to change as the program changes. u Social and political considerations must be balanced with u The science of risk assessment and u Business and financial interests

108. 6/1/99ASTM RBCA for Chemicals User Training 108 Key Points u Three levels of decisions – the whole program, site-specific and business-specific. – consensus among stakeholders important at all levels. – decisions must deal with uncertainty u Important issues are: – the level of stakeholder involvement – groundwater use and point of demonstration; – target and cumulative or additive risk – adequacy of site assessment – land use – ecological risk assessment

109. Developing the Site Conceptual Model

110. 6/1/99ASTM RBCA for Chemicals User Training 110 Risk Management under RBCA Planning and scoping technical policy decisions site conceptual model Iterative evaluation data collection fate & transport analyses Risk-based decisions further evaluation remedial action interim remedial action

111. 6/1/99ASTM RBCA for Chemicals User Training 111 Receptors: Residents Commercial or Industrial workers Construction workers Recreational Users Relevant Ecological Receptors and Habitats PRIMARY SOURCES SECONDARY SOURCES EXPOSURE ROUTES RECEPTORS TRANSPORT MECHANISMS Affected Sub-surface Soils (> 3 ft depth) Sources: Product Storage Piping/Distributi on Operations Waste Mgmt Units Other Above Ground Storage Tank Piping Leaching and Ground Water Transport GROUND WATER Potable Water Use Commercial or Industrial Workers Source Area: Surface Soils Subsurface Soils Dissolved Ground Water Plume Non-Aqueous Phase Liquid (NAPL) Sediments Transport Mechanisms: Wind Erosion & Atmospheric Dispersion Volatilization and Enclosed Space Accumulation Leaching to Ground Water Transport Mobile NAPL Migration Storm water/Surface Water Transport Exposure Routes: Dermal Contact Ingestion Inhalation of Particulate Inhalation of Vapors Potable Water Use: Ingestion Cooking Showering Cleaning Swimming Exposure Pathway SourceTransportReceptor

112. 6/1/99ASTM RBCA for Chemicals User Training 112 Site conceptual model (SCM) u An inventory of sources, transport mechanisms, and receptors u Exposure pathway analysis – focus on complete exposure pathways – current and reasonable potential future land and water use – hydrogeologic characteristics u Factor in characteristics of the material – both toxicity and physical/chemical u Account for potential mitigating factors – including regional characteristics

113. 6/1/99ASTM RBCA for Chemicals User Training 113 Initial Site Assessment Initial SCM Risk-based Decision Remedial Action Collect Additional data Tier upgrade Refined SCM Site Conceptual Model Development u Working hypothesis of site management needs – Updated as new data become available u Valuable communication tool

114. 6/1/99ASTM RBCA for Chemicals User Training 114 u Source/Source Area – a source and mechanism for chemical release into the environment – physical/chemical, toxicological properties Source Sources, Transport Mechanisms and Receptors

115. 6/1/99ASTM RBCA for Chemicals User Training 115 u Means by which a chemical moves from source to receptor – transport medium (e.g., air, soil, ground water) – mechanism (e.g.,ground water flow, air dispersion) Transport Sources, Transport Mechanisms and Receptors

116. 6/1/99ASTM RBCA for Chemicals User Training 116 Sources, Transport Mechanisms and Receptors

117. 6/1/99ASTM RBCA for Chemicals User Training 117 Receptor Sources, Transport Mechanisms and Receptors u Based on reasonable potential current & future land and water use – residents - visitors – relevant ecological receptors & habitats – reasonable potential future receptors

118. 6/1/99ASTM RBCA for Chemicals User Training 118 Sources, Transport Mechanisms and Receptors u Point of Exposure - A point of potential contact of the receptor with the medium u Route of Exposure - means for taking the chemical into the body Receptor

119. 6/1/99ASTM RBCA for Chemicals User Training 119 Sources, Transport Mechanisms and Receptors u Relevant ecological receptors and habitats – identify specifies and habitats – develop exposure scenarios – how do we identify? Receptor

120. 6/1/99ASTM RBCA for Chemicals User Training 120 Example of a conceptual model

121. 6/1/99ASTM RBCA for Chemicals User Training 121 Example of a conceptual model (ASTM PS-104-98)

122. 6/1/99ASTM RBCA for Chemicals User Training 122 Example of a conceptual model (RAGS Part D)

123. 6/1/99ASTM RBCA for Chemicals User Training 123 Another example of a conceptual model From Guidelines for Ecological Risk Assessment, EPA/630/R-95/002F, 4/98, Final

124. 6/1/99ASTM RBCA for Chemicals User Training 124 Exposure Pathway Analysis u For each complete exposure pathway, a quantitative evaluation of risk can be performed

125. 6/1/99ASTM RBCA for Chemicals User Training 125 Exposure Pathway Analysis u A quantitative evaluation of risk can be performed for each complete or potentially complete exposure pathway ExposureConcentration xExposureFactors= Health Risk x Toxicity Target Level Calculation Risk Estimation

126. 6/1/99ASTM RBCA for Chemicals User Training 126 Assessing risk along a pathway Source Conceptual Model Transport Source Concentrations Risk Estimation Exposure Concentrations Dose Health Risk Target Level Calculation Allowable Risk Allowable Source Concentrations Receptor

127. 6/1/99ASTM RBCA for Chemicals User Training 127 More site-specific Each step uses a Model Less site-specific Components of risk assessment Fate & Transport Exposure Toxicity Dose Exposure Concentrations Health Risk Source Concentrations

128. 6/1/99ASTM RBCA for Chemicals User Training 128 Risk Characterization Dose- Response Assessment Exposure Assessment Transport Assessment Source Characterization Fate &Transport ExposureToxicity Health Risk Source Concentrations Exposure Concentrations Dose Risk Assessment Process

129. 6/1/99ASTM RBCA for Chemicals User Training 129 RESEARCH RISK ASSESSMENT RISK MANAGEMENT Understanding the mechanistic linkages between: Sources  Exposure  Dose  Response (1) Hazard Identification (2) Exposure  Dose  Response Assessment (3) Exposure Assessment (4) Risk Characterization (5) Identification of Research Needs Risk Management Options Public Health, Economic, Social, Political Consequences of Options Risk Management Decisions and Actions Adapted from “Science and Judgement in Risk Assessment”, NRC, 1994 Classic risk assessment paradigm

130. 6/1/99ASTM RBCA for Chemicals User Training 130 Ecological Risk Assessment u Follows a tiered evaluation similar to human health risk assessment u Parallel BUT NOT identical to human health risk assessment u Site conceptual model assists in – putting together scenarios – determining potential risk and exposure

131. 6/1/99ASTM RBCA for Chemicals User Training 131 Ecological Risk Assessment u Important questions in ecological risk assessment are: – what is important to protect? – how do we identify relevant ecological receptors and habitats? u Requires extensive – problem formulation – discussion of technical policy decisions with the regulatory agencies

132. 6/1/99ASTM RBCA for Chemicals User Training 132 Planning and scoping technical policy decisions site conceptual model Iterative evaluation data collection fate & transport analyses Risk-based decisions further evaluation remedial action interim remedial action Risk Management under RBCA

133. 6/1/99ASTM RBCA for Chemicals User Training 133 Transport Exposure Assessment Data Collection u Primary objective – evaluate pathways in order to make risk- based decisions u Fundamentally need to address – what? where? how much? when? – uncertainty in estimate u Data quantity and quality needs vary with tiers and decision-points – screening level versus modeling effort versus validation

134. 6/1/99ASTM RBCA for Chemicals User Training 134 Transport Source Exposure Assessment Sources u Chemicals of concern – e.g., physical, chemical, toxicological u Representative concentration u Physical setting – e.g., soil characteristics, hydrogeology, climate

135. 6/1/99ASTM RBCA for Chemicals User Training 135 Transport Exposure Assessment Fate & Transport u Partitioning between media u Cross-media transfers – soil-to-groundwater leaching – migration in groundwater – soil-to-air migration u Simple to more complex u Empirical versus modeling data u Variability and uncertainty

136. 6/1/99ASTM RBCA for Chemicals User Training 136 Exposure Exposure Assessment Other Considerations u Land and water use – reasonably current and potential – typically defines receptors u Pathway selection – fate & transport important u Exposure assumptions – who, how much and how often u Chemical availability (bioavailability) u Variability and uncertainty

137. 6/1/99ASTM RBCA for Chemicals User Training 137 Toxicity Toxicity assessment u Non-carcinogenic effects – leads to the development of malignant cells reference Dose (RfD) (mg/kg-day) (oral, dermal) reference Concentration (RfC) (mg/m3) (inhalation) u Carcinogenic effects – impacts the development, size or functioning of the whole body or specific organs (including skin and the nervous system) but does not lead to the development of malignant cells – cancer slope factor (or cancer potency factor) (mg/kg- day)-1 unit risk (mg/m3)-1 (inhalation, oral)

138. 6/1/99ASTM RBCA for Chemicals User Training 138 Dose-Response Curve (non-carcinogenic effects) RfD NOAEL LOAEL Dose (mg/kg/day) % Response LOAEL - Lowest Observed Adverse Effect Level NOAEL - No Observable Adverse Effect Level RfD - Reference dose X Toxicity Assessment Non-Carcinogenic Effects Toxicity

139. 6/1/99ASTM RBCA for Chemicals User Training 139 Toxicity Toxicity Assessment Non-Carcinogenic Effects u Reference Dose = NOAEL/(UF1 * UF2 *.... * MF) – Uncertainty Factor(s) (UF) (uncertainty factor is set equal to 10) account for variation in general population to protect sensitive subpopulation. extrapolate from animals to humans to account for interspecies variability. estimate a chronic NOAEL derived from a subchronic study. estimate NOAEL from LOAEL.

140. 6/1/99ASTM RBCA for Chemicals User Training 140 Toxicity Toxicity Assessment Non-Carcinogenic Effects u Reference Dose = NOAEL/(UF1 * UF2 *.... * MF) – Modifying Factor (MF) (ranges from > 1 to 10 with a default of 1) reflects a qualitative professional assessment of additional uncertainties in the study and in the entire database for the chemical(s) of concern and not explicitly addressed in the uncertainty factors.

141. 6/1/99ASTM RBCA for Chemicals User Training 141 Hypothetical Dose-Response Curve (carcinogenic effects) 0 5001000 | Human exposure | |Animal experiments range| range Dose (mg/kg-day) 0 0.05 0.1 * * * * * * 95% UCL Occurrence of Cancer Toxicity Assessment Carcinogenic Effects Toxicity

142. 6/1/99ASTM RBCA for Chemicals User Training 142 Toxicity Toxicity Assessment Carcinogenic Effects EPA Weight-of-Evidence Classification System for Carcinogenity GroupDescriptionExamples A Human carcinogen, with sufficient evidence from epidemiological studies Benzene B1 or B2 Probable human carcinogen B1 - with limited evidence from epidemiological studies B2 - with sufficient evidence from animal studies and inadequate evidence or no data from epidemiological studies Benzo(a)pyrene C Possible human carcinogen, with limited evidence from animal studies in absence of human data PCE D Not classifiable as to human carcinogenicity, owing to inadequate human and animal evidence Ethylbenzene Toluene Xylenes E Evidence of noncarcinogenicity for humans, with no evidence of carcinogenicity in at least two adequate animal tests in different species or in both adequate animal and epidemiological studies

143. 6/1/99ASTM RBCA for Chemicals User Training 143 Toxicity Toxicity Assessment u Sources of toxicity information (in order of preference) – state specific toxicity values – Integrated Risk Information System (IRIS) only RfDs and slope factors that have been reviewed by EPA. no external peer review of safe dose estimates (RfDs, SFs). – EPA Criteria Documents – Health Effects Assessment Summary Tables (HEAST) summarizes all toxicity data. no internal or external peer review of quality of data. – Agency for Toxic Substances & Disease Registry ( ATSDR) – peer-reviewed literature

144. 6/1/99ASTM RBCA for Chemicals User Training 144 Toxicity Assessment u New directions – benchmark dose – mechanistic Toxicity

145. 6/1/99ASTM RBCA for Chemicals User Training 145 Risk Risk Characterization u Quantifying non-cancer effects u Quantifying cancer effects u Other considerations – cumulative risk/additive effects – addressing uncertainty and variability – synergistic effects

146. 6/1/99ASTM RBCA for Chemicals User Training 146 Risk Risk Characterization u Quantifying cancer risks – estimated as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen IELCR = Cancer Slope Factor x Lifetime Average Daily Dose IELCR = Individual Excess Lifetime Cancer Risk u Development of target risk is a policy decision

147. 6/1/99ASTM RBCA for Chemicals User Training 147 Risk Risk Characterization u Quantifying non-carcinogenic effects – evaluated by comparing the estimated dose with the safe dose (reference dose or reference concentration). – ratio is called the Hazard Quotient (HQ) HQ = Intake / safe dose Intake = Applied Dose or Absorbed Dose – For single chemical evaluation, an HQ<1 means the chemical does not show an effect – Technical policy on additive effects of multiple chemicals

148. 6/1/99ASTM RBCA for Chemicals User Training 148 ExposureConcentration x Exposure Factors (Intake) = Health Risk x Toxicity (Slope Factor) Target Level Calculation Example Quantifying Carcinogenic Risks u Residential drinking water

149. 6/1/99ASTM RBCA for Chemicals User Training 149 Intake (mg/kg-day) = C W x IR x EF x ED BW x AT C W = Concentration in Water of chemical of concern (mg/l) IR= Ingestion Rate (l/day) EF= Exposure Frequency (days/yr) ED= Exposure Duration (yr) BW= Body Weight (kg) AT= Averaging Time (period over which exposure is averaged) (days) For noncarcinogens: AT = ED * 365 days per year and intake is called Chronic Daily Intake (CDI). For carcinogens: AT = Lifetime (70 years) * 365 days per year and intake is called Lifetime Average Daily Dose (LADD). Example Quantifying Carcinogenic Risks u Intake Equation for Ingestion of Drinking Water

150. 6/1/99ASTM RBCA for Chemicals User Training 150 Example Quantifying Carcinogenic Risks Note: value shown in parenthesis represents child value a - 365 days per year x 70 year lifetime u Exposure Factors for ingestion of drinking water

151. 6/1/99ASTM RBCA for Chemicals User Training 151 IELCR (Risk) = Slope Factor (SF) x Intake C w = Risk x BW x AT SF x ED x EF x IR Risk = SF x C W x IR x EF x ED BW x AT Example Quantifying Carcinogenic Risks u Calculating concentration in ground water (Cw) - ground water ingestion

152. 6/1/99ASTM RBCA for Chemicals User Training 152 Class Exercise # ?? Quantifying Carcinogenic Risks u An adult drinks water containing 0.05 mg/l benzene for 30 years. – estimate the Individual Excess Lifetime Cancer Risk – estimate the concentration of benzene that will result in an acceptable risk of 1 X 10 -5 The slope factor for benzene is 2.90E-02 (mg/kg-d) -1

153. 6/1/99ASTM RBCA for Chemicals User Training 153 Deterministic Calculation u Probabilistic risk analysis (PRA) addresses both variability and uncertainty. Example: Residential drinking water pathway

154. 6/1/99ASTM RBCA for Chemicals User Training 154 Concentration (ppm) 0.000.040.080.120.16 Forecast: Residential Drinking Water Pathway Mean = 0.03 ppm Point Estimate = 0.002 ppm 95th Percentile = 0.002 ppm Median = 0.01 ppm Risk Level = 10 -6 Probability Deterministic Calculation Probabilistic Risk Analysis Results

155. 6/1/99ASTM RBCA for Chemicals User Training 155 Risk Management Risk-Based Decisions u Policy Decisions – how much risk is acceptable? – data quantity and quality – use of engineering/institutional controls – ecological receptors and habitats to be considered u Other Factors – economics, community issues, aesthetics Transport