Presentation on theme: "CE 510 Hazardous Waste Engineering"— Presentation transcript:
1 CE 510 Hazardous Waste Engineering Department of Civil EngineeringSouthern Illinois University CarbondaleInstructor: Jemil YesufDr. L.R. ChevalierLecture Series 10:Hazardous Waste Risk Assessment
2 Course GoalsReview the history and impact of environmental laws in the United StatesUnderstand the terminology, nomenclature, and significance of properties of hazardous wastes and hazardous materialsDevelop strategies to find information of nomenclature, transport and behavior, and toxicity for hazardous compoundsElucidate procedures for describing, assessing, and sampling hazardous wastes at industrial facilities and contaminated sitesPredict the behavior of hazardous chemicals in surface impoundments, soils, groundwater and treatment systemsAssess the toxicity and risk associated with exposure to hazardous chemicalsApply scientific principles and process designs of hazardous wastes management, remediation and treatment
3 Risk AssessmentThe ultimate goal is to provide a quantitative basis for making decisions involvinghazardous waste treatmentRemediationDisposal optionsWaste minimizationSiting new facilities (incinerators, Landfill)Is a key part of CERCLA and SARASee page 519 for two extremes of risk
4 What is Risk?Chance of encountering the potential adverse effects of human and ecological exposures to environmental hazardsPut simply;RISK = TOXICITY x EXPOSUREToxicity = contaminant’s ability to cause adversityExposure = The route to receptors and the concentration of the contaminant
5 4 Steps for Risk Assessment (EPA) Hazardous IdentificationWhat chemicals exist at the site and are of potential concern?Exposure assessmentHow might a receptor be exposed on or off site?Toxicity AssessmentAt what level of exposure are adverse effects likely to occur? – Receptor analysisRisk CharacterizationWhat are the risks and uncertainties at the site? – e.g. one in hundred, or one in one million
6 Human Health Risk Assessment Data Collection and EvaluationExposure AssessmentToxicity AssessmentRisk Characterization
7 Checklist for Human Health What human receptors are near your site?Are residential properties close by?Is site access restricted?What contaminants are present?Is there a threat or demonstrated release?What media have been impacted?What data are available?
8 Exposure AssessmentIdentify and estimate concentrations of chemicals potentially affecting human health or ecological receptorsCharacterize the site in terms of:Physical characteristicsSoil characteristics, surface water location, groundwater (flow depth), meteorologyExposed populationsHuman activities and land use (recreation, residential/industrial/commercial)Proximity to releasePotential future uses
9 Identify exposure pathways Develop a conceptual site model Determine amount of exposure for each pathway using monitoring data or fate and transport modelsWhat do you mean by size of individuals?Analyze concentrations, frequency and duration of contaminant exposure to population groupsConsider characteristics of affected population groups - age of individuals, age, unique exposure considerations, other factors
10 Toxicity AssessmentCompare dose of contaminant with incidence of adverse human health effect to ascertain relationship (quantitative toxicology)Determine whether exposure to certain chemicals results in adverse health effectsEvaluate available toxicity informationDatabases - IRIS (EPA)Identify data gapsInvestigate human health problems near the site
11 Risk Characterization Combine information gathered in the Exposure Assessment and Toxicity AssessmentQuantify risks to human health from individual chemicals and exposure pathwaysSum risks for various exposure scenariosEvaluate cancer risk, non-cancer hazard separately (Eqns and 11.9 Textbook)Describe all assumptions, areas of uncertainty
12 Ecological Risk Assessment RCRA and CERCLA requires EPA to remediate uncontrolled hazardous waste sites in a way that protect both human health and the ENVIRONMENT.National Contingency Plan requires that the four steps be used for risk assessment to characterize the current and potential threats to both public health and the ENVIRONMENT.
14 Effects on Ecosystem Reduction in population size Change in community structureChanges in ecosystem structure and function
15 Sources of Uncertainties Source characterizationLack of available dataExposure assessment models and methodsToxicology data
16 Risk Assessment versus Risk Management Risk assessment – unbiased scientific approach to assessing riskRisk management – incorporates the results of risk assessment, factors in societal values, legal mandates, other considerationsRisk communication is a critical piece of each of these
17 Risk ManagementThe process of weighing policy alternatives and selecting the most appropriate regulatory action by integrating the results of risk assessment with engineering data in addition to social, economic, and political concerns to reach a decision.
18 Communicating Risk Human response to risk is not always rational Level of risk play little role in acceptability to publicEmotional response often makes it difficult to communicate riskPeople apply personal values when evaluating risk
19 Factors Affecting Risk Perception Voluntary vs. InvoluntaryFamiliar vs. UnfamiliarVisibility of ThreatCatastrophic vs. Non-catastrophicNatural vs. Man-madeAffects Adults vs. ChildrenTrusted vs. Untrusted CommunicatorEqual vs. Unequal Benefits
20 Covello’s Cardinal Rules of Risk Communication Accept and involve the public as a legitimate partnerPlan and carefully evaluate communication effortsIdentify audience, understand problems, pretest messageListen to public’s specific concernsBe honest, frank and open
21 Cardinal Rules Continued Coordinate and collaborate with other credible sourcesMeet needs of mediaSpeak clearly and with compassion