United States Environmental Protection Agency Office of Emergency Remedial Response Washington, DC 20460 EPA/540/X-91/002 April 1991 Superfund Risk Assessment in Superfund: A Primer FIRST EDITION September 1990 ------- 9285.7-05 RISK ASSESSMENT IN SUPERFUND: A PRIMER FIRST EDITION September 1990 U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Emergency and Remedial Response Toxics Integration Branch An introduction to risk assessment for Superfund Remedial Project Managers (RPMs) and On-Scene Coordinators (OSCs) Printed on Recycled Paper ------- r \ MAKING RISK ASSESSMENT WORK FOR YOU TOXICS INTEGRATION BRANCH Hazardous Site Evaluation Division Office of Emergency and Remedial Response (OS-230) 202-475-9486 FTS 475-9486 V J ------- Risk Assessment in Superfund: Introduction The major decisions made at a Superfund site can be distilled into answering these basic questions: • Should something be done at this site? • What should be done? • When has enough been done? The Comprehensive Environmental Response, Compensation, and Liability Act (known as Superfund) is a law passed by Congress in 1980 and amended in 1986. Superfund allows the U.S. Environmental Protection Agency (EPA) to reduce the risks from hazardous chemical wastes where the environment has been damaged. Written by EPA, the National Contingency Plan (NCP) is the regulation to implement and carry out Superfund law such that it protects the health of both people and the environment. Different risk assessment approaches are applied in evaluating possible effects of Superfund sites on human health and the environment. In the Superfund program, the application of risk assessment to human health evaluation is well developed and standardized. It is outlined in this primer. Neither EPA nor the Superfund program has one standardized environmental evaluation methodology, because there are so many different aspects of the environment -- individuals, species, ecosystems, natural resources, endangered species, etc. -- which may need to be evaluated. As a result, the Superfund program has identified resource persons to be involved and an orderly process for environmental evaluation. This primer refers the reader to the guidance for environmental evaluation (see appendix A), but it does not provide details of the process. Regardless, the protection of the environment remains of primary importance, along with the protection of human health, in the Superfund program. i ------- Part I Risk Assessment in Superfund - An Overview 1-1 ------- EPA'S RISK PARADIGM Risk Risk Risk Assessment ^ Management ~ Communication 1-2 ------- To help answer the basic questions at Superfund sites, EPA has chosen to use a structured methodology known as risk assessment to decide what is "safe" or "protective." EPA has chosen this common sense approach to assemble and organize information on the toxicity (potential harmful health effects) of a chemical and exposure (contact of an organism with a chemical) of the individuals at or near a Superfund site. Managers at EPA can then use the assembled information from the risk assessment to make decisions to act ~ a process known as risk management. The communication to EPA staff, as well as the public, of the results of the risk assessment and decisions made in the risk management process is known as risk communication. All programs within EPA use the risk assessment, risk management, and risk communication paradigm in some manner. The Superfund program has been a leader in applying it to site- specific decisions. This primer illustrates this application. 1-3 ------- THE FOUR STEPS OF RISK ASSESSMENT Exposure Assessment Toxicity Assessment Data Collection and Evaluation Risk Characterization 1-4 ------- Risk assessment for a Superfund site is a four-step process. The first step, data collection and evaluation, identifies contaminants present in the environmental media -- soil, groundwater, surface water, air, fish, etc. ~ of the site. The second step, toxicity assessment, uses the results of years of research and testing of the effects of chemicals on the health of people and animals to decide which of the contaminants found on site might pose a health threat. The third step, exposure assessment, defines which pathways (e.g., using the groundwater for drinking and showering or eating the fish) might bring the contaminants in contact with people. The final step, risk characterization, brings the information from the first three steps together to determine the potential severity of health threats from the site. 1-5 ------- RISK ASSESSMENT IS... A Structured Method Used to Evaluate Potential Effects of Environmental Contaminants. Residential Area Swamp City (10 miles) Stream Woods River — Hill Fields 1-6 ------- This primer shows risk assessment to be a particularly helpful way to view the extent of a problem at a Superfund site. 1-7 ------- HEALTH AND ENVIRONMENTAL RISK ASSESSMENT To inform: • Pre-remedial program • Removal program • Remedial program ------- Those in the Superfund program usually talk about the "baseline risk assessment" conducted during the remedial investigation. In fact, risk assessment is useful to managers throughout the Superfund process. The Hazard Ranking System of the pre-remedial program is structured by risk assessment principles. Risk assessment can also help trigger removal actions, set preliminary remediation goals, and determine when a site is "clean". 1-9 ------- BASIC QUESTIONS ANSWERED WITH RISK INFORMATION How bad is the site? How bad could it become if nothing is done? Does the site warrant remedial action? How much should be cleaned up for the site to be o.k.? What will be the result of remedial action? I-IO ------- Here are some of the questions risk assessment can answer. 1-11 ------- RISK ASSESSMENT AND SUPERFUND Remedial Investigation Preliminary Assessment, Site Inspection, Listing Site Inspection Remedial Design/ Remedial Action (RD/RA) Record of Decision (ROD) Selection of Remedy Site Discovery HRS Scoring NPL Listing Project Scoping 5 Year Review Feasibility Study Answers to Risk Questions Aid in Risk Data Collected and Identified hisk Decision-making Process Assessment Conducted 1-12 ------- Most of the formal risk assessment activities occur after a site is listed on the National Priorities List (NPL). Major opportunities for risk assessment to help in site decision- making include: developing preliminary remediation goals during project scoping and their modification during the feasibility study (FS). the baseline risk assessment during the remediation investigation (Rl). evaluating the effectiveness of remedial alternatives: in the FS report, in the Record of Decision (ROD) to relate target cleanup concentrations to health risks; during remedial action to monitor progress toward "acceptable risk"; and at deletion or five-year review of the site. 1-13 ------- DEVELOPMENT OF PRELIMINARY REMEDIATION GOALS Future Land Potential Exposure Points ARARs 10 Point of Departure i * Target Cleanup Concentrations ------- Risk assessment can provide a quick way to estimate risk- based target clean-up concentrations for the site at the start of the Rl, relying only on data used for NPL listing, a prediction of future land use (residential or industrial), a standard set of exposure factors in a look-up table, standard toxicity values, and a calculator. This allows consideration of possible risks from several pathways of exposure to each chemical (e.g. people drinking groundwater, kids eating dirt.) It also allows explicit consideration of the "10"® point-of- departure" (one in a million individual excess lifetime cancer risk) called for in the National Contingency Plan (NCP) as a starting point for remedial analysis. Finally, it allows for a quick protectiveness check on possible chemical-specific applicable or relevant and appropriate requirements (ARARs) for a site. These are potential target cleanup concentrations suggested by Federal or State laws. 1-15 ------- BASELINE RISK ASSESSMENT Residential Area Farmlands Swamp ft/City (10 miles) Woods River 1-16 ------- The baseline risk assessment organizes the information from the Rl to answer the questions shown. Part II of this primer provides more detail how these steps are conducted. The reasonable maximum exposure (RME) is called for in the NCP and should provide a "rationally conservative" estimate of exposures from the site. 1-17 ------- EFFECTIVENESS EVALUATION OF REMEDIAL ALTERNATIVES 1-18 ------- An effective remedy will: . protect human health and the environment. provide short-term effectiveness (acceptable risk during the cleanup). provide long-term effectiveness (risk assessment can evaluate progress or completion of cleanup). 1-19 ------- MAKING RISK ASSESSMENT WORK REAL TIME Guidance & Training ¦ Real World _Jseat sidPo«« , w»"0 (— Concerns uuaiity Control Cleanup Concerns 1-20 ------- EPA Regional and Headquarters (D.C.) personnel share responsibility for making risk assessment work. The Superfund program is delegated to the Regions, and, of course, the action takes place at the site. Regional or State staff must plan, carry out, monitor, and evaluate actions at the site. Staff in the Regions (we call them Regional Toxics Integration Coordinators) assist site managers and Regional management in using risk assessment in Superfund. Regional staff should also maintain a quality control program for risk assessments at each site. Staff at EPA Headquarters lead, usually with Regional participation, the development of risk assessment guidance and training, the provision of "rapid response" technical support, and quality assurance of risk assessments. Both Regional and Headquarters risk assessment programs identify the need for new policies or research or testing to fill gaps in knowledge. Together, our goal is to improve and facilitate high quality and nationally consistent risk assessment in the Superfund program. 1-21 ------- ENVIRONMENTAL EVALUATION MANUAL Replaces (with Human Health Evaluation Manual) Endangerment Assessment Handbook (1985) Audience: • Remedial project managers • On-scene coordinators Goals: • Establish a process • Involve experts • Assess and report consistently 1-22 ------- Here's the latest guidance for environmental (ecological) evaluation at Superfund sites. It's available from the Center for Environmental Research Information (CERI) in Cincinnati, Ohio. To order, phone (513) 569-7562 (FTS 684-7562). The order number is EPA/540/1-89/001. 1-23 ------- HUMAN HEALTH EVALUATION MANUAL Replaces Superffund Public Health Evaluation Manual (1986) Replaces (with Environmental Evaluation Manual) Endangerment Assessment Handbook (1985) Audience: • Risk assessor • Risk assessment reviewer Goals: • Be clear • Be specific • Be useful • Be used 1-24 ------- There's also new guidance for human health risk assessments. Order EPA/540/1-89/002 from CERI. 1-25 ------- SUPERFUND TOOLS HEALTH ENVIRONMENT Human Health Evaluation Manual (Part A) (1989) Risk Assessment Guidance For Superfund Environmental Evaluation Manual (1989) Superfund Exposure Assessment Manual (1988) Integrated Risk Information System Health Effects Assessment Summary Tables (quarterly) Ecological Assessment of Hazardous Waste Sites: A Field and Laboratory Reference (1989) Guidance for Data Useability in Risk Assessment (1990) 1-26 ------- The two manuals we just described make up Risk Assessment Guidance for Superfund (RAGS). Additional parts of RAGS, addressing preliminary remediation goals (RAGS-Part B) and Record of Decision (ROD) and post-ROD activities (RAGS-Part C), will be published in Summer 1991. The other risk assessment tools, documents and databases, are aimed at risk assessors and risk assessment reviewers. 1-27 ------- WHERE DO I TURN FOR HELP? OSCs... Senior OSC State Environmental Experts r? [£( osc* Environmental Response Team (ERT) 1-28 ^Technical Support Centers Technical Assistance Team (TAT) National Response Center (NRC) ------- Here are some folks who are available to help the on-scene coordinator as he or she leads removal activities. 1-29 ------- WHERE DO I TURN FOR HELP? RPMs... Regional Biological Technical Assistance ^Groups (BTAGs)/ Environmantal rtoandAsMasi Offic# (ECAO) ------- Two sources of help for Remedial Project Managers (RPMs) need additional explanation: The BTAG is a group of environmental biology/natural resource experts (employees of EPA, U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, or States) organized in the Region to provide environmental evaluation and review of Superfund sites. ECAO, an office within EPA's Office of Research and Development, answers telephone or written inquiries for technical health risk assessment support from RPMs, OSCs, or Superfund risk assessors. The phone number is (513) 569-7300 (FTS 684-7300). 1-31 ------- QUESTIONS? 9 9 9 9 9 9 9 9 9 9 9 9 9 1-32 ------- If you have questions about the use of risk assessment in the Superfund program, call Toxics Integration Branch (202) 475-9486 FTS 475-9486 1-33 ------- Part II Risk Assessment in Superfund - Some Details n-i ------- United States Office of Emergency and EPA/540/1 -89/002 Environmental Protection Remedial Response December 1989 Agency Washington DC 20460 Superfund Risk Assessment Guidance for Superfund Volume I Human Health Evaluation Manual (Part A) Interim Final ------- This part of the risk assessment primer lays out the steps of human health risk assessment as described in Risk Assessment Guidance for Superfund: Volume I: Human Health Evaluation Manual (Part A). n-3 ------- HUMAN HEALTH RISK EVALUATION ACTIVITIES IN THE RI/FS PROCESS RI/FS Stages r Project Scoping Site C haracteriza t ion (RD RI/FS Establishment of Remedial Action Objectives (FS) Development & Screening of Alternatives (FS) Detailed Analysis of Alternatives (FS) Human Health | Risk Evaluation 1Activities Review data collected in site inspection Review sampling/data collection plans Formulate preliminary remediation goals (RGs) Determine level of effort for baseline risk assessment RISK ASSESSMENT Toxicity Assessment Data Collection and Evaluation 1 Risk Characterization Exposure Assessment Refine preliminary RGs based on risk assessment and ARARs Evaluate risk of remedial alternatives ] n-4 ------- The baseline risk assessment of the Remedial Investigation (Rl) is the central risk evaluation activity in the Superfund program. It is a four-step risk assessment paradigm (data evaluation, exposure assessment, toxicity assessment, risk characterization) adapted from recommendations to EPA by a committee of the National Academy of Sciences in 1983. This four-step analysis or framework is used in each risk evaluation step in the Superfund remedial program. n-5 ------- HUMAN HEALTH EVALUATION MANUAL Evaluation of Remedial Alternatives (Part C) Development of Preliminary Remediation Goals (Part B) Baseline Risk Assessment (Part A) n-6 ------- Let's look at the baseline risk assessment as described in Part A of RAGS. n-7 ------- COLLECT DATA Stream Residential Area Swamp Woods — Hill - Site History PA/SI/LSI Scoping Collections Sampling Strategy City (10 miles) River Fields Analytical V. Methods n-8 ------- To initiate the baseline risk assessment of the Rl, information on site history and data gathered during the pre-remedial program (PA/SI/LSI) or a recent site visit must be assembled and used to guide the "scoping" of the remedial investigation. A critical part of the scoping, in which the risk assessor or Regional Toxics Integration Coordinator can assist greatly, is identifying contaminants of significant toxicity- and all exposure pathways of concern. In addition to the media paths - soil, air, and drinking water -- other paths such as the eating of contaminated food or recreation may be very important. Knowing toxicity and exposures to be evaluated leads directly to sampling strategy (e.g., identifying "hot spots," gathering sufficient data for reasonable maximum exposure (RME) determination), appropriate analytical methods (e.g., requesting special analytical services for detection at low concentration), and related data quality objectives (DQOs) for sampling and analysis. n-9 ------- EVALUATE DATA Spatial Distribution Detection Frequency Background Concentrations Lab Data 40J Data Evaluation Chemicals of Potential Concern 14,000a Detection Limits Laboratory Blanks Data Qualifiers n-io ------- Evaluation of data, from lab or field analyses, identifies chemicals of potential concern at the site. Staff of the Environmental Services Division (ESD) of the Region evaluate data from the Contract Laboratory Program (CLP) and other sources against DQOs. ESD staff provide standard laboratory reports for data from the CLP. These data often have certain codes (e.g., J) to help their interpretation. Coded data are not "bad" data; they are often extremely helpful to the risk assessor. For example, a code may indicate the presence of a chemical on site at a concentration below the sample quantitation limit. n-11 ------- ASSESS EXPOSURE Residential Area Farmlands City (10 miles) Woods • Characterize Physical Setting; • Analyze Contaminant Releases; • Identify Potentially Exposed Populations; • Identify Potential Exposure Pathways; • Estimate Exposure Point Concentrations; • Estimate Contaminant Intake; • Integrate Exposure Assessement; • Highlight Uncertainties. n-12 ------- The exposure assessment looks for complete pathways of exposure to particular types of people on or near the site. The activities of the people determine the exposure. Exposure assessment follows the seven steps shown in the box below. For our site, exposure paths shown in the circles seem important, and the risk assessor chose them for detailed analysis: • Does the site contaminate the groundwater used for drinking and other household activities by the residents across the stream from the site? • Has dust from the site contaminated yards so that children might eat it? Will browsing game eat contaminated soils on plant roots? • Do runoff and groundwater discharges to the stream contaminate the river (water or sediments) and make their way into fish, crops, or the city's water supply and then into people? • Are some populations subjected to combined exposures of several pathways, e.g., is a child across the stream eating the fish brought home all summer by his brother? The baseline risk assessment considers both present exposures and those that might result from current or probable future land use, if no further cleanup action is taken at the site. n-13 ------- ASSESS EXPOSURE Five Basic Variables Used to Estimate Intake Exposure Point Concentrations: Contact Rate: 11? Exposure Frequency/Duration: Body Weight: 9 Exposure Averaging Time: 9 Calendar S M T W T F S 111 < ¦*-. i 9 ~ ft? n-i4 ------- For each exposure pathway, the risk assessor must decide upon five basic variables to use in estimating intake. The first, exposure point concentration, is unique to the site and path. To achieve greater consistency in exposure assessment site- to-site and across the country, the RAGS and other guidance being developed recommend specific "default" values for most other variables. The risk assessor may still select a site-specific value rather than a default, but that site-specific value should be explicitly justified, and its impact described, in the risk assessment report. n-15 ------- ASSESS EXPOSURE Reasonable Maximum Exposure (RME) Definition: Highest exposure that is reasonably expected to occur at a site, considering • land use • intake variables • pathway combinations Intent is to estimate a conservative exposure case that is still within the range of possible exposures. n-i6 ------- RME, introduced in the National Contingency Plan, is identified and illustrated in the RAGS. RMEs are estimated for individual exposure pathways to generate a "conservative" case (i.e. exposure well above the average case) that is still within the range of possible exposures. Thus people at or near sites will be protected; cleanups will not be driven by assumed exposures outside the range of possibility. Risk assessors should consider RME under both current and future land-use conditions. The exposure point concentration used to calculate the RME should be a conservative estimate of the arithmetic average. (The RAGS suggests the 95 percent upper confidence limit.) Calculations based on average and worst-case concentrations are no longer recommended, although managers may still request them as a type of uncertainty analysis. n-17 ------- ASSESS TOXICITY For chemicals of potential concern, what are... Types of Effects • Carcinogenic • Developmental • Acute • Subchronic • Chronic (noncarcinogenic) Qualitative Factors? • Animal experiments • Human evidence • Weight of evidence (A,B,C) • Animal experiments • Human evidence Quantitative Factors? • Non-threshold effects • Animal to human extrapolation • High to low dose extrapolation • Threshold effects • Uncertainty factors • Animal to human extrapolation • High to low dose extrapolation Toxicity Values? • Slope factors • Units = (mg/kg/day) • Reference doses (RfDs) • Units = mg/kg/day n-i8 ------- The risk assessor's answers to the questions listed above determine the toxicity of each chemical found at the site. Sources of information to answer the questions are identified on the next page. When information is lacking, risk assessors must make and explicitly justify professional judgement. n-19 ------- ASSESS TOXICITY Hierarchy of Toxicity Data Sources Health Effects Assessment Summary Tables (HEAST) • Provides interim as well as verified RfDs and slope factors • Should be used only for chemicals not addressed in IRIS Integrated Risk Information System (IRIS) • Provides verified reference doses (RfDs) and slope factors • Updated monthly • EPA's preferred source of toxicity information Other EPA References • Do not necessarily provide verified RfDs and slope factors • Should be used only for chemicals not found or referenced in IRIS or HEAST • EPA's Environmental Criteria and Assessment Office must be contacted first (513-569-7300; FTS 684-7300) n-20 ------- Here are databases and resources for assessing the toxicity of chemicals: IRIS is EPA's primary reference source, reflecting Agency-wide consensus. HEAST is produced for the Superfund program to complement IRIS and provide for accurate, timely assessments. It is updated quarterly and provided to Regional Toxics Integration Coordinators (RTICs) and Superfund risk assessment contractors. The Environmental Criteria and Assessment Office (ECAO) provides consultation, review, and analysis. Each Region has its own policy for referral of Superfund risk assessment contractors to ECAO; the RTICs know the policy. n-21 ------- ASSESSING TOXICITY CARCINOGENS UNIT CANCER RISK Linearized Multistage Model (95% upper confidence limit) Chemical A Chemical B RESPONSE DOSE (mg/kg/day) Models like the Linearized Multistage Model transform high-dose data into low-dose estimates n-22 ------- Toxicologists assess the carcinogenicity (cancer-causing potential) of a substance by studying the effects (number and type of tumors) of different doses (milligrams of substance applied per kilogram of body weight per day), often on laboratory animals. Doses that result in a sufficient number of tumors in a small population of animals to be statistically significant are often much higher than would occur at the concentration of a substance at a Superfund site or somewhere else in the environment. Thus, models are used to extrapolate effects from high (laboratory) dose to low (environmental) dose. Our current understanding of carcinogenicity suggests that even at very low doses, there is some probability of response, i.e., there is no threshold. n-23 ------- ASSESSING TOXICITY EPA RISK ASSESSMENT GUIDELINES FOR CARCINOGENS 1 Group A Human Carcinogen Group B Probable Human Carcinogen Group C Possible Human Carcinogen Group D Not Classifiable 1 1 n-24 ------- In addition to estimating quanitative toxicity values for carcinogens, toxicologists also make qualitative evaluations of the sum total of all studies using a given substance. These are often called weight-of-evidence classifications. EPA has standardized this approach a five-class grouping. In general, multiple well-designed studies, studies showing adverse effects in several species of animals, and particularly for Group A, evidence of adverse effects in humans provide greater weight-of- evidence of carcinogenicity. The Superfund risk assessor uses this classification in the risk characterization discussion of the risk assessment. n-25 ------- ASSESSING TOXICITY NONCARCINOGENS Rfd NOAEL DOSE (mg/kg/day) A Series of Decreasing Doses Finally Elicits No Adverse Effects. A Safety Margin is Applied to this No Adverse Effects Level n-26 ------- Different doses of noncarcinogens also result in different responses. In this case, though, there is a low dose for which there is no observed adverse effect (NOAEL), i.e. there is a threshold. To protect for uncertainties (e.g., applying the results of animal studies to effects in humans) EPA divides the NOAEL dose by one or more uncertainty factors (UF) to determine a Reference Dose (RfD) that is probably safe. n-27 ------- CHARACTERIZE RISK Combine Toxicity and Exposure Assessments For Mixtures and Reasonably Anticipated Multi-Media Exposures, Assume Additivity Characterize Uncertainties Clearly Present Risks] and Uncertainties for Risk Manager n-28 Document Results ------- Once the exposure and toxicity assessments are complete, the risk assessor must characterize the risks. This step is crucial for communicating both to managers who must decide what actions to take at the site, and to the public, who may live at or near the site. n-29 ------- CHARACTERIZE RISK Example of Presentation of Relative Contribution of Individual Chemicals to Exposure Pathway and Total Cancer Risk Estimates Nearby Resident Population Excess Lifetime Cancer Risk < 3 x 10"4 W 10-1. AC w a> u § 10"* • 0 • E 1 10"® 0 8 1. x 111 & i 10 -8 _ 10-- 10" Bmzmw CMonJan* Pubic Water Supply * 2 x 10"4 (B2) Contaminated Fish < 1 X1(T*(B2) n-30 ------- A presentation to characterize risk from cancer-causing chemicals might try to show: sources of risk (water supply, fish) risk from individual chemicals (benzene, chlordane) how strong is the evidence for a chemical to cause cancer in humans (B2, A) that risks are probably less than the limits illustrated in the graphic (upper-bound, <) Excess lifetime carcinogen risks to individuals of less than 104 (1 in 10,000) do not require remedial actions at Superfund sites. Actions may be taken to reduce risks below 10"4. If the baseline risk assessment shows risks greater than 104 to individuals, then initial clean-up target concentrations corresponding to 10"6 risk, the "point of departure," are chosen. n-3i ------- CHARACTERIZE RISK Example of Presentation of Relative Contribution of Individual Chemicals to Exposure Pathway and Total Hazard Index Estimates Chronic Hazard Indax ¦ 0.6 e 0j6 _ n-32 ------- For chemicals which show non-cancer risks from chronic (long- term) exposures, the risk assessor estimates a hazard index (HI). His greater than 1 are a sign to the RPM to look closely at possible need for remedial action. Risk assessors can advise the RPM whether any His should be added to estimate risk. n-33 ------- CHARACTERIZE RISK Presenting Uncertainties Physical setting Exposure parameter assumptions Land use Model applicability and assumptions Toxicity values Multiple substances 7 n-34 ------- Characterization of risk requires presentation of uncertainties. The items shown in the picture are some of the factors contributing to uncertainty in risk characterization. The risk assessor's job is to help the site manager and others explore the uncertainties and the characterization. n-35 ------- HUMAN HEALTH EVALUATION MANUAL Baseline Risk Assessment (Part A) Development of Preliminary Remediation Goals (Part B) Evaluation of Remedial Alternatives (Part C) n-36 ------- Risk assessment provides a means for developing preliminary remediation goals. n-37 ------- DEVELOP PRELIMINARY REMEDIATION GOALS Mixtures Multi-Media Carcinogenic Risk Assessment "Model" Noncarcinogenic Target •Risks" otectiveness Environmental Concentrations ^ State Standards MCLGs ARARs AWQC n-38 ------- The NCP directs that Applicable or Relevant and Appropriate Requirements (of other Federal or State statutes) (ARARs) and other readily available information be used to develop preliminary remediation goals (PRGs), (i.e., first estimates of acceptable concentrations of chemicals in environmental media at the site). The Toxics Integration Branch is completing Part B of RAGS to provide a very simple way to use risk assessment to determine many PRGs as early as Rl scoping. PRGs would then be confirmed or modified in later remedial steps. n-39 ------- HUMAN HEALTH EVALUATION MANUAL Baseline Assessment (Part A) Development of Preliminary Remediation| Goals (Part B) Evaluation of Remedial Alternatives (Part C) n-40 ------- Risk assessment aids in evaluating remedial alternatives in the Feasibility Study, ROD, during remedial action, and at the end of cleanup (delisting) or at the continuing five-reviews. Part C of RAGS, in preparation, will describe each of these steps, each answering in its way, "How clean is clean?" n-4i ------- EVALUATE REMEDIAL ALTERNATIVES Residential Area Swamp City (10 miles) Woods -River Fields Releases? -Construction -Planned - Accidental . Chemicals? jr. j] Pathways? Residual Risks? NCP 9 Criteria 1. Overall protection of human health and the environment 2. Compliance with ARARs Threshold Criteria 3. Long-term effectiveness and permanence 4. Reduction of toxicity, mobility, or volume 5. Short-term effectiveness 6. Implementability 7. Cost Primary Balancing Criteria 8. State Acceptance 9. Community Acceptance Modifying Balancing n-42 ------- Remedial alternatives are evaluated against nine criteria. The remedy selected in the Record of Decision best satisfies the criteria. Risk assessment can address several of these: Overall protection of human health and the environment is a threshold criterion that the selected remedy must satisfy. Risk analysis for long-term and short-term effectiveness demonstrate this "protectiveness." A risk assessment that relates concentrations of chemicals expected after remediation to residual risks remaining at the site provides a measure of long-term effectiveness. This risk assessment should be summarized in the decision summary of the ROD. A remedy that presents no unacceptable risks during the remedial action meets the short-term effectiveness criterion. Activities at the site may release contaminants, create new pathways of exposure, or even new chemicals. Risk assessment can evaluate these. Every ROD should, at a minimum, identify the contaminants posing risks, target concentrations for cleanup, points of compliance for cleanup in each medium, and the risks that will remain after completion of the remedy if cleanup goals are achieved. n-43 ------- On paper, risk assessment is straightforward, logical, maybe even easy. In practice, each site is unique, and data will be lacking, uncertainties will require all involved to use professional judgement, and the best justified and designed remedies will behave in surprising ways. You can still apply risk assessment methodology at any time (from the first site inspection to deletion) you have data on toxicity and exposure to make a better, reasoned decision. n-45 ------- Appendix A Risk Assessment Tools A-l ------- Ecological Assessment of Hazardous Waste Sites: A Field and Laboratory Manual. March 1989. EPA/600/3-89/013. Available from CERI. Exposure Factors Handbook. July 1989. EPA/600/8-89-043. Available from CERI. Guidance for Data Useability in Risk Assessment. EPA/540/G-90/008. Available from CERI. Health Effects Assessment Summary Tables (HEAST). Limited copies available for risk assessors from Toxics Integration Branch (202) 475- 9490 or FTS 475-9490. Integrated Risk Information System (IRIS). Database access available from IRIS User Support (513) 569-7254. A-2 ------- Risk Assessment Guidance for Superfund: Volume I: Human Health Evaluation Manual (Part A). December 1989. EPA/540/1-89/002. Available from CERI. - - (Part B). In draft. Available from CERI Summer 1991. -- (PartC). Indraft. Available from CERI Summer 1991. Risk Assessment Guidance for Superfund: Volume II: Environmental Evaluation Manual. March 1989. EPA/540/1-89/001. Available from CERI. Superfund Exposure Assessment Manual. April 1988. EPA/540/1-88/001. Available from CERI. Center for Environmental Research Information (CERI) 26 W. Martin Luther King Drive Cincinnati, Ohio 45268 (513) 569-7562 FTS 684-7562 "U.S. Gowommert PiWtng Office; 1981— 550434 A-3 ------- |