Lecture Notes SPEA-E311
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SPEA E311 Lecture Notes History of Risk Assessment Frameworks 1 National Research Council 1983 3 parts Research Risk Assessment and Risk Management 1 Based on 39red book 2 2 Research 1 Laboratory amp Field observations 2 High to low dose extrapolation methods 3 Field measurements estimated exposures 3 Risk Assessment 1 Hazard Identi cation Identify most dangerous compound or chemical in a 39cocktail of hazards More than one chemical can cause mortality 2 DoseResponse Assessment 3 Exposure Assessment 4 Risk Management 1 Regulatory options Evaluation of adverse and bene cial consequences of regulatory oonns 5 Combining and I how bad it is a Agency decisions and actions RAGS 1996 Initial Framework 1 Baseline Risk Assessment a Data collection and evaluation Hazard ID i Gather and analyze site data ii Identify potential concerns b Toxicity Assessment i Collect qualitative and quantitative toxicity information ii Determine appropriate toxicity values c Exposure Assessment i Analyze contaminant releases ii Identify exposed populations iii Identify exposure pathways 1 One large exposure small amount of exposure over long period of time iv Estimate concentrations through exposure pathways v Estimate contaminant intake d Risk Characterization i Potential for adverse health effects to occur 1 Estimate cancer risks 2 Estimate noncancer hazard quotients a Neurological reproductive developmental ii Evaluate uncertainty iii Summarize risk information SPEA E311 Lecture Notes EPA Risk Assessment Paradigm 1997 1 Ecological Risk Assessment Human Health Risk Assessment Risk Management RlSk Assessment Background and Legal Mandate Risk Assessment is the process used by the EPA in the Superfund program to protect human health and the environment from current and potential threats posed by uncontrolled hazardous substance release Based on a strategic framework that de nes chemicals of concern target organism effects toxicity and associated impacts Process Overview Congress decides what the statute CERCLA Superfund is the law amended by SARA Skeleton overall framework D Agency decides how to enact statute through regulation D Guidance ex RAGS change frequently gives all details thorough explanation of method and measuring techniques Project Scoping Complete data sets No Most typically miscellaneous data thrown together in document work with what we have Data is expensive to collect Look for data like ACTUAL DATA IS LOCATED IN APPENDIX OF IDEM DOCUMENT Measures of chemistry water quality ground and surface water and rain D collected through state and federal agencies 0 Level of contaminants within organisms biota burden plants included Sediment soil w water on top underneath a riverbed and soil on land contamination Air quality and composition In GaryHammond area measured to be among worst in US 0 PAH s from car emissions pollute air 0 Major highways cross through this area Data Collection Plan additional data after preliminary assessment 0 Design a plan of study to collect exact data need Quality Assurance Project Plan QUAPP Formulate remediation goals 0 Diminishing returns cost v cleanup RlFS Baseline Risk Assessment focus of this semester 2 Site discoveryPreliminary Assessment Site lnspection NPL Listing a Gather and analyze existing relevant site data i Tertratech did not sample air quality 1 Air quality data available through National Weather Service 2 As a risk reviewer give speci c recommendations for remedying missing air quality assessment b Address modelling parameter needs c Collect background data i Look outside of Grand Calumet look at other rivers in region SPEA E311 Lecture Notes ii Indiana Dunes National Park Service located within region had collected data on contaminate numbers in area d Conduct preliminary exposure assessment what is my organism doing i Use standard numbers for weight gender surface area exposed D EPA has standardized gures e Devise overall strategy for sample collection sampling and projects are EXPENSIVE f Examine QAQC Quality AssuranceQuality Control measures i Measure at number lower than toxicity level g Identify special anaytica needs i Measure list of parameters what detection levels ii If below toxicity level there will be no number if above tox level there will be a number h Identify potential chemicals of concern i 39toxic cocktails deal with chemical most toxic in smallest amount i Take active role in work plan development and data coect i Must attend work plan meetings risk reviewers only what to do things that project absoutey needs Conceptual Evaluation Model 0 Sources 0 Variables Contaminants concentration time locations 0 Hypotheses to be tested source exists sources can be contained source can be removed and disposed source can be treated Pathways 0 Variables media rates of migration time loss and gain functions 0 Hypotheses Pathway exists pathway can be interrupted pathway can be eliminated Receptors 0 Variables Types Sensitivities time concentrations numbers 0 Hypotheses Receptor is not impacted by migration of contaminants receptors can be relocated institutional controls can be applied receptor can be protected Data Evaluation 1 Combine data available from site investigations 2 Evaluate analytical methods 3 Evaluate quantitation limits 4 Evaluate quali ed and coded data 5 Evaluate blanks 6 Evaluate tentatively identi ed compounds a List of two chemicals 7 Compare site data with background 8 Identify chemical of potential concern a Tetratech identi ed 4 Toxicity Assessment 5 Exposure Assessment 6 Risk Characterization determined through toxicity amp exposure assessments a Cancer causing SPEA E311 Lecture Notes b Noncarcinogenic reproductive neurological developmental c SAME CHEMICAL CAN CAUSE BOTH CANCER ON NONCANER AFFECTS 7 Selection of RemedyDRemedial designRemedial Action Exposure Assessment 1 Characterize physical setting a Also done in data collectionevaluation and in prelim screening i Try to understand rami cations on present and future 2 Identify potentially exposed populations a Target populations i Residents and visitors ii Human population 1 Ethnicity age groups Who lives in or near site 3 Identify potential exposure pathways a Rain groundwater surface water runoff water from site drinking water soil 4 Estimate exposure concentrations a Cannot force individuals to give sampleDhair blood b Must calculate approximate exposures 5 Estimate chemical intakes a Methods b Media Applicable exposure pathways speci c to ea organism Water SedimentSoil Air Dermal Inhalation ln estion Toxicity Assessment 1 Gather quantitative and qualitative toxicity information for substances being evaluated a symptoms health effects i Where to look b lethal dose for example 2 Identify exposure periods for which toxicity values are necessary SPEA E311 Lecture Notes a Exposure on a i Short daily exposure over lifetime ii Large exposure over short period of time 1 Which is worse The one that will kill you The one that causes cancer b What kind of values i No safe level ex Lead ii DoseResponse any given concentration gives a response 1 lazy Scurve Threshold doseMaximum response100 lethal typically associated with noncaner point at which 12 organisms die no organisms die graphically diagonal line typically associated with cancer causing chemicals 3 Determine toxicity values for noncarcinogenic effects a We would prefer people not to be dying maintain a safe level 4 Determine toxicity values for carcinogenic effects a is the 39safe level determined by EPA some sensitive components of the population will yield response with exposure Risk Characterization Review outputs from toxicity and exposure assessments Quantify risks from individual chemicals Quantify risks from multiple chemicals Combine risks across exposure pathways a Dermal b Inhalation c ingestion 5 Assess and present what we don t really know and why we make the assumption we ve come to 6 Consider sitespeci c human studies a Can we use existing literature or studies from the area on different populations to make assessments about the population of concern b Often existing studies give very good qualitative data rather than quantitative i ie studies done on steel workers in china can be used comparatively for studies of US steel workers ii sometimes genetic predisposition should be taken into account PUN Data CollectionData Evaluation 1 Collect Existing Data a Site speci c data i Initial site discovery ii Prescreen evaluation iii Local state deferral inspections b Area speci c data i Stream survey SPEA E311 iii iv v vi vii Address modeling parameter needs Collect background data Conduct preliminary exposure assessment Describe overall strategy for sample collection Examine QAQC measures Identify special analytical needs Take active role during work plan development and data collection 90 0 9999quot Lecture Notes Industrial selfmonitored information in dailymonthly operating reports 1 Polluting industries must selfreport MOR s monthly operating reports a EPA validates reports at risk of imprisonment industries must report accurately Toxic Release inventory TRI STORET EPA waterquality database Discharge data DMR EPA violations database Drinking water databases National Listing of Fish Advisories Background Data Suggests representative of 39control from areas not exposed or contaminated a Not pristine not presettlement conditions b Greater than mortality in control is cause for concern a Naturally occurring b Anthropogenic human nonsite additions Site Visit 0 Exposure pathways 0 What route chemicals take to target organism TO 0 Identify TOs Conducts 39prelim exposure assessment Applicable exposure pathways speci c to ea organism Water SedimentSoil Air Biota living organisms Dermal Inhalation lngeonn Determine boundaries and transport of contaminants o How it moves into system 0 Determine magnitude frequency and duration of exposure Quality Assurance Quality Assurance Project Plan QAPP 1 Determine overall sampling plan for site 2 to sampling EPA requires details of sampling plan a Details of led methods b Details of laboratory chemical analysis methods c Anticipated health and safety concerns SPEA E311 Lecture Notes d Acceptable loss of samplesprecision and accuracy data quality objectives DQOs e Correction f Extensive documentation including all methods Data Quality Objectives 1 Identi es data usage a primary b secondary data is comparable originally designed for a prior project can be applicable to present study 2 Needs for chemical physical and biological information 3 Review speci c data needs a Precision Accuracy amp Representativeness i Range of values that method is good for b Completeness c Comparability i Duplicates ii Should I expect to get the same answer 4 Datacollection program a Sampling and analysis plan SAP b Work Plan WP c Enforcement concerns i Necessary for preparation in possible legal cases Data Evaluation Combine data available from site investigations Evaluate analytical methods Evaluate quantitation limits Evaluate quali ed and coded data Evaluate blanks Evaluate tentatively identi ed compounds Compare the data with background Identify chemicals of potential concerns hy Evaluate Gather all available data Evaluate analytical methods Evaluate quality based on quantitation limits Evaluate with respect to data quali ers and codes Evaluate data with respect to blanks Evaluate tentative compounds Compare site contaminant levels to background Develop set of data for risk assessment delete redundant compounds with same modes of action Data Evaluation Comparison of QAPP and DQO requirements to existing information based on 0 Analytical methods identi ed in QAPP Quantitation methods identi ed in QAPP Quali ed and coded data ie data quali ers Evaluate blanks and QA samples 90gt 9 P PPUNl E P gt Pquot39gtE quot SPEA E311 0 eld blanks duplicates 0 method detection limits MDLs Lecture Notes 0 Special Analytical Services SAS with CLP labs Data Quali ers Combine data so can compare apple to apples Flags Description R Rejected Result is not acceptable for use in decision making process J Estimated The use of the result in decision making processes will be determined on a case by case basis Don t know exact concentration estimated concentration but chemical has been positivey identi ed in sample Between MDL amp RL l the result of the parameter is above the Method Detection Limit MLD but below the Lab Reporting Limit RL and will be estimated Nondetect because measurement tool is not precise enough cannot measure small enough QC Checks or Criteria One or more of the QC checks or criteria are out of control RPPD for Duplicates The Relative Percent Difference RPD for parameter is outside the acceptable control limits The parameter will be considered estimated or rejected on the basis listed below 1 If the Sample or Duplicate value is less than the RL and the other value exceeds 5 times the MDL then the sample will be estimated 2 If the RPPD is outside the established control limits max RPD but below two times the established control limits max RPD then the sample will be estimated 3 If the RPD is twice the established control limits mass RPD or greater then the sample will be rejected Blanks and Flags Blank Contamination this SPEA E311 Lecture Notes parameter is found in a eld or a lab blank Whether the result is accepted estimated or rejected will be based upon the level of contamination listed below 1 If the result of the sample is greater than the reporting limit but less than ve times the blank contamination the result will be rejected 2 If the result of the sample is between ve and ten times the blank contamination the result will be estimated 3 If the result of the sample is less than the reporting limit or greater than ten times the blank contamination the result will be accepted Nondetect does not necessarily mean 0 H Holding Time the analysis for this parameter was performed out of the holding time The results will be estimated or rejected on the basis listed below 1 If the analysis was performed between the holding time limit and 15 times the holding time limit the result will be estimate d If the analysis was performed outside the 15 times the holding time limit the result will be rejected UUN Grand Calumet amp Surrounding Area Historically a wetland Slow ow shallow wide pools with many links between them sh from Lake Michigan came to spawn can no longer access Indiana Harbor Third largest in port in United States Only separation from Lake Michigan is steel barrier Used primarily as dumping place for hazardous chemicals being lled with sand and other materials to form land Roxana Marsh Historically known as important migratory bird area Used to determine water toxicity 1 response is cause for concern SPEA E311 Lecture Notes Used to determine cell proliferation cancer causing 100 response in East Chicago Sanitary West Branch Grand Calumet River Reach 4 Colombia Avenue to Sohl Road 0 Indianapolis Blvd to IllinoisIndiana state line 0 Grand Calumet River Restoration Fund not enough money to dredge entire river EPA decided to break river up into segments 1 Area of concern has many parks recreational areas area also previously contained 39fecal island 2 Invasive tall grass species over takes cattail habit shaded out other plant species a Root systems take up and absorb toxins in water but form such a dense mat that water and land boundaries are unclear 3 Area is very dangerous many physical dangers shopping carts cars rebar concrete slabs as well as contaminated water and soil 4 River is not very deep and ows in both directions bottom is comprised of very ne silts and particulates very soft East Branch Grand Calumet River Largest portion DuPont pesticide company USX Lead EPA refused to issue discharge permit Data Gap 1 More topographic information 0 Establish riverbed topography and core sample elevations Data Gap 2 Need engineering base drawings 0 Historical sampling location 0 Proposed sapling location 0 Layout prelim dredge Data gap 3 Transfer sediment core data to base drawings 0 Calculate Xyz sediment core data locations based on bathymetric survey 0 Place data on base maps Proposed sampling Many samples proposed most taken problems with taking others Data Gap 5 Need information on access sites 0 Shallow water bank stability to equipment insertion dewatering hauling Data gap 6 Local sources of services and Material 0 Information is need on SPEA E311 Lecture Notes 0 Local labor Dredging equipment 0 Construction equipment 0 Fleet vehicles 0 Aggregate and sand 0 Concrete related services Blinky the Gold sh From Roxana Marsh Deformed missing one eye mouth on opposite side of head where there are no eyes Blinky wasn t the only one brothers and sisters that look just like him Roxana Marsh has been completely stripped now prepared to be leak proof so that none of the underlying material will ever mix with the habitat again Sediments Chemicals of Concern PCB Aroclor amp Congeners Organochlorine Pesticides Semivolatile organic Metals RCRA Oil amp Grease Total organic Carbon 0 Acid Volatile Sul des Remediation Options amp Cleanup Goals Previous use of sediment quality Guidelines in the Grans Calumet River Indiana Harbor Canal 0 US Steel CWARCRANRDA consent decrees Hammond SD CWA litigation GCRlHC NRDA Sediment lnjury Determination Could we use same approach from US Steel in West Branch lRemove banks river materials until at 39parent material ended up being 21 feet in depth over 13 miles 0 Review reports available on Oncourse is there a problem or isn t there It is not possible to remove all contaminated material the question is how much can we leave in place mixing with clean material for an acceptable death rate DoseResponse Relationships Dose 0 Exposure Dose amount of a xenobiotic encountered in the environment Absorbed dose actual amount of the exposed does that enters the body Administered dose quantity administered usually orally or by injection 0 Total dose sum of all individual doses SPEA E311 Lecture Notes Response Change from normal state on molecular cellular organ or organism levellj symptoms Graded response degrees of the same symptom Quantal all or none DoseResponse Linear no threshold Nonlinear exponential curve threshold rst point on graph where response yield above zero Scurve iIIustrates LD50 lethal dose 50 dose at which 50 die 0 May also see EC50 refers to concentration induces a response halfway between the baseline and maximum after a speci ed exposure time Not every organism responds the same way using deviation of response we can assess LD50 is within say 90 of given range yields Types of Toxic Response 0 Acute short term exposure 0 Chronic repeated exposure bioaccumulation occurs threshold is reached gradually o Carcinogens cause cancer 0 Mutagens cause mutations in organisms genetic material 0 Teratogens cause birth defect in offspring foIIow exposure of a pregnant female Idiosyncratic Allergic Local 0 Systemic Reversible Irreversible One Toxicant can have both acute and chronic toxicity Toxicant Acute Toxicity Chronic Toxicity Ethanol CNS depression Liver cirrhosis Arsenic Gastrointestinal Skinliver cancer damage Toxicity Interactions Additive 224 Synergism 231O o If exposed at same time overall effect is higher than sum of individual effects 0 Increased activity resulting from the effect of one chemical on another LD50 DDT 250mgkg LD50 synergist 1000mgkg LD50 DDT synergist 50mgkg Potentiation O35 0 One chemical not harmful on its own second chemical might be harmful when exposed together overall effect is greater than sum of individual effects one chemical releases the toxic potential of another chemical SPEA E311 Lecture Notes Antagonism 2 2 O 0 Chemical antagonism One chemical inactivates another chemical o Dispositionalantagonism Fate of the toxin is altered one toxin prevents the other from migrating 0 Functional antagonism Effects of chemicals cancel each other out 0 One raises heart rate the other lowers heart rate 0 Pharmacologicalantagonism Action of both chemicals are occurring at same site in essence block the action of each other Epidemiology Study Looking at already exposed populations Cohort Study Experimenters expose and study population The Knows Clinical studies LD50 test results Disease correlations Population studies The Unknowns Toxic effects of chemical interaction lmprecise knowledge of exposure 0 Windows of vulnerability Thousands of unstudied chemicals 0 Long latency periods 0 Behavior lifestyle variables 0 Genetic predispositions Toxicity Assessment for Noncarcinogenic Effects Steps in Toxicity Assessment 1 Gather toxicity information qualitative and quantitative for substances being evaluated 2 Identify exposure periods for which toxicity values are necessary 4 Determine toxicity values for carcinogenic effects 5 Summarize toxicity information K k f f k What kind of values Qualitative symptoms health effects Quantitative ie lethal dose 104106 is the 39safe level determined by EPA some sensitive components of the population will yield response with exposure Exposure on a continuum short daily exposure over lifetime large exposure over short period of time no safe level ie lead doseresponse curve threshold dose gt maximum responsegt 100 lethal typically noncarcinogenic LD50 NOEL ll nl I 39 IVUHEL Slope factor graphically diagonal line typically carcinogenic saqu aana l Summarize toxicity information Determine toxicity values for carcinogenic effects Determine toxicity values for noncarcinogenic effects Identify exposure periods for which toxicity values are necessary Gather toxicity information qualitative and quantitative for substances being eval ted IIEEI39VEIdS SPEA E311 Lecture Notes Chronic RfD Chronic data is most important because it is worstcase scenario De nition An estimate with uncertainty of daily exposure level for human populations including sensitive subpopulations that is likely to be wo an appreciable risk of deleterious effects during a life time 0 Protective for longterm exposure to a compound 0 Used to evaluate potential Noncarcinogenic effects associated with shorterterm exposures Rst 0 Developmental Rst used to assess potential developmental effects from exposure to a compound over two weeks to 7 years 0 Important for limited of years or short halflife chemical degrades to negligible concentrations within several months Used to evaluate potential effects on a developing organism following a single exposure event Multiple Toxic Effects 0 The reference dose RfD is developed from NOAEL for the most sensitive or critical toxic effect based in part on the assumption that if the critical toxic effect is prevented then all toxic effect are prevented During the risk characterization if exposure levels exceed the RfD then adverse effects in addition to the critical toxic effect may begin to appear Steps to Develop RfDo Examine all available studies following exposure by the oral route evaluate AQQCie determine scienti c merit If no oral exposure data is available then use other exposure eg inhalation routes 0 Use human data otherwise use animal information and determine scienti c quality 0 If using animal data EPA seeks to identify the animal model this is most relevant to humans 0 In the absence of a species that is most relevant ie most relevant to humans based on defensible biological rationale using comparative metabolic and pharmacokinetic data then assume humans are at least as sensitive as the most sensitive animal species EPA Science Policy 0 Study on the most sensitive species ie species showing a toxic effect at the lowest administered dose is selected as the critical study for the basis of the RfD LOEL is adjusted for species differences and is the critical toxic effect 0 After critical study and toxic effect are selected EPA identi es the experimental exposure level representing the highest level tested at which no adverse effects including the critical toxic effect were demonstrated 0 The NOAEL is the key datum obtained from a doseresponse relationship The NOAEL is an animal study with intermittent exposure is adjusted to re ect continuous exposure Selection of NOAEL NOAEL is not the same as the NOEL SPEA E311 Lecture Notes NOEL corresponds to exposure level at which no effect at all has been observed frequently effects are observed that are not considered to be of toxicological signi cance 0 In some studies only the LOEL is available need to add uncertainty factors Applying Uncertainty Factors RfD is derived from the NOAEL or LOEL for critical toxic effect by consistent application of uncertainty factors UFs and a modifying factor MF Uncertainty factors generally consist of multiples of 10 although values less than 10 can sometimes be used 0 Each factor represents a speci c area of uncertainty inherent in the extrapolation from the available data Basis for UF UFWZ UF1gtIltUF2 UFX o UF is expressed is scienti c notation ie 131O3912 Modifying Factor MF MF ranging from gtO1O is included to re ect a qualitative professional assessment of additional uncertainties in the critical study and in the entire database 0 Done for chemicals not explicitly addressed by the uncertainty factors 0 The default MF value is 1 no difference MF of 3 and 10 used for increasing levels of uncertainty Calculation UF leszUFxgtltMF RfD NOAEL z L0EL z RfDo typically expressed as one sig g in units of mgkgday Most EPA Rst IRIS are based on administered doses not absorbed doses Identi cation of Inhalation RfD RfDi More complex than oral exposure 0 Dynamics of respiratory system and diversity across species 0 Differences in the physiochemical properties of contaminants Selecting the most critical study depends on the respiratory system which may affect pattern of contaminant deposition in the respiratory tract and the clearance and redistribution of the agent SPEA E311 Lecture Notes 0 Different species may not receive the same dose of the contaminant at the same locations within the respiratory tract even though both species were exposed to the same particle or gas concentrations 0 Differences in physiochemical characteristics such as size and shape of the particle aerosol or gas in uence deposition clearance and redistribution Considerations 0 Target tissue may be a portion of the respiratory tract or if the contaminant can be absorbed and distributed through the body some extra respiratory organ 0 Pattern of deposition may in uence concentrations at the alveolar exchange boundary or different tissues of the lung Toxic health effects observed may be more directly related to pattern of deposition than exposure concentration Effective Dose Considers the deposition clearance mechanisms and the physiochemical properties of the inhaled agent in determining the effective dose delivered to target organ Equivalent Doses Dose calculation in animals converted to equivalent in humans on the basis of comparative physiological considerations 0 Includes ventilator parameter regional lung surface areas Considers discontinuous exposures periods by adjusting to re ect continuous exposures UF RfDi Derived from the NOAEL by applying uncertainty factors similar to those previously described 0 UF 10 used when extrapolating from animals to human in addition to calculation of human equivalent dose accounts for interspeci c variation in sensitivity to toxicant o RfD value is reported as a concentration In air mgm3 for continuous 24hrday exposure or as Inhaled intake mgkgday and a concentration in air mgm3 Human body weight of 79 kg and inhalation rate of 20 m3day to convert between inhaled intake and a concentration in air Subchronic RfD RfDS Chronic Rst are for lifetime or other longterm exposures may be overly protective if evaluating less than lifespan exposure Subchronic Rst generated by EPA but have not undergone intraagency workgroup veri cation considered interim not in IRIS 0 Similar in concept to chronic RfD except exposure duration RfD derived from NOAEL using UFs and MFs UFs for RfDS When experimental data are available for shorter exposure duration than desired and uncertainty factor is applied 0 Similar in approach to application of UFs for duration differences if chronic RfD is estimated from subchronic animal data SPEA E311 Lecture Notes o If subchronic data are missing and chronic oral RfD is adopted as subchronic oral RfD there is no application of an uncertainty factor Derivation of Developmental Toxicant RfDdt De nition potential of a substance to cause adverse effects in a developing organisms as a result of exposure prior to conception either parent during prenatal development or postnatal 0 Examples death structural abnormalities altered growth functional de ciencies Maternal toxicity is determined from weightof evidence designation Weight of Evidence for Developmental Toxicity De nitive evidence for 0 Human developmental toxicity 0 No apparent human developmental toxicity Adequate evidence for 0 Potential human developmental toxicity 0 No apparent potential human developmental toxicity Inadequate evidence for determining potential human developmental toxicity De nitive amp Adequate evidence are subdivided by whether evidence demonstrates the occurrence or the absence of adverse effect Procedure for Reference Dose Development Toxicant 1 Weightofevidence designation assigned D a study selected for identi cation of NOAEL 2 NOAEL converted to equivalent human dose if necessary and divided by UFs similar to those used in development of an oral RfD 3 RfDdt based on short duration of exposure a Even single exposure during a critical time ie during gestation may produce adverse developmental effects and chronic exposure may not be needed for developmental toxicity to be present 4 Usually not adjusted for duration of exposure OneDay and TenDay Health Advisories EPA Of ce of Drinking Water determined reference values for evaluating potential adverse effects associated with oral exposures of shorter duration Oneday amp Tenday Health Advisories are concentrations of contaminants in drinking water at which adverse health effects would not be expected to occur for an exposure of speci ed duration UF 221 gtlt UF2gtlt UFX gtlt MF Health Advisory NOAEL Z LOEL amp Calculation based on a 10kg child assumed to drink 1L waterday includes a margin of safety to protect sensitive members of the population Veri cation of Rst 0 EPA RfD Workgroup reviews con icting data and resolves toxicity assessments and toxicity values SPEA E311 Lecture Notes 0 Reviews information in derivation of an RfD and summarizes it evaluation conclusions and reservations regarding RfD in a standardized summary 0 Provides important considerations on con dence in RfD the critical study and overall database high medium low 0 Approved information entered into IRIS called veri ed Rst o Rst awaiting approval ie chronic Rst are considered interim Rst E No subchronic Rst or developmental Rst workgroups have been formed Toxicity Assessment for Carcinogenic Effects Slope Factors Steps in Toxicity Assessment 1 Gather toxicity information qualitative and quantitative for substances being evaluated 2 Identify exposure periods for which toxicity values are necessary 3 Determine toxicity values for Noncarcinogenic effects 5 Summarize toxicity information Considerations for Carcinogenic Effects Slope Factor and accompanying weightofevidence determinations are the toxicity data most commonly used to evaluate potential human carcinogenic risks Assumptions 0 Cancer de nition EPA assumes that small number of molecular events can evoke changes in a single cell that can cause uncontrolled cellular proliferation and clinical state of disease Nonthreshold carcinogenesis is the hypothesized mechanism assumed that essentially no level of exposure to such a chemical does not pose a nite probability possibly small of generating a carcinogenic response 0 No 39safe level of cancer linear response problematic as soon as response leaves 0 o D No dose is risk free so an effect threshold cannot be estimated Assigning Weight of Evidence Evaluation process 1 Determine likelihood that agent is a human carcinogen a Evidence is characterized separately for human and animal studies 2 Characterization of two types of data are combined and based on the extent that the agent is a known carcinogen in experimental animals or humans or both 3 lAgent is given a provisional don t know toxicity catchall classi cation weightof evidence classi cation based on international Agency for Research on Cancer IARB 1982 SPEA E311 Lecture Notes Weight of Evidence Classi cations for Carcinogenicity Group Description A Human Carcinogen Bl Probable Human Carcinogen limited human data available 32 Probable Human Carcinogen suf cient evidence in animals and inadequate or no evidence in humans Possible Human Carcinogen Not Classi ed as Human Carcinogen E Evidence of noncarcinogenicity for humans on G rating SI eFactor l o A toxicity value quintitatively de nes the relationship between does and 39 factor 0 Typically calculated for potential carcinogens in classes ie A Bl 82 Quantitative estimating of slope factors for chemicals in class C proceeds on a casebycase basis 0 Becomes a plausible upperbound estimate of probability of a response per unit intake of a chemical over a lifetime 0 Should always be accompanied the weightof evidence classi cation to indicate strengm of evidence that the agent is a human carcinogen Identify Appropriate Data Sets To derive slope factors Unit risk on IRIS is NOT the same as slope factor but slope factor CAN be calculated from unit risk 1 Review available information about a chemical and select appropriate data set a Prefer data sets of highquality human exposure rather than animal data i If must use animal data select species responding similarly to humans ie metabolism physiology and pharmacokinetics ii If clear choice is not possible seect most sensitive Species and give greatest emphasis iii If no single study use geometric mean of collective studies estimate to ensure inclusion of all relevant data SPEA E311 Lecture Notes Extrapolating to Lower Doses Dif cult to measure risk at low doses using either animals or epidemiologic studies 0 Generally apply a model to available data set and extrapolate from high doses administered to lower doses expected for human contact in the environment 0 Choice of lowdose extrapolation model is determined by consistency with current understanding of mechanisms of carcinogenicity not only on goodnessof t to the observed tumor data 0 If data are limited and uncertainty exists in mechanism of carcinogenicity action preferred use of lowdose linearity when compatible with limited information content 0 EPA recommends linearized multistage model in absence of adequate information Linearized Multistage Model ql slope factor 2 risk per unit dose absorbed dose per day 8 Model Choices Models predict less conservative ie lower cancer potency than linearized multistage model Weibull Probit Logit Onehit Gama multihit models Timetotumor models Toxicity Values Unit Risks Based on risk per unit concentration of substances in a medium where human contact occurs anit risk 2 slope factor x kg gtlt air V water anit risk x 10 3 Unit risk air 20 m3day water 2 Lday If absorption factor is lt 10 used in deriving the slope factor use an additional conversion factor in unit risk to base on an administered dose basis Standardized duration assumption is continuous lifetime exposure so no absorption conversion is required 0 10393 converts the mg slope factor or ql given in mgkg per day 391 to ug risk is ugm or ugL l Model Fitting Once data are t to the appropriate model the upper 95th con dence limit of the slope of doseresponse curve is determined SPEAE311 Lecture Notes Represents an upper 95th con dence limit on probability of a response per unit intake of a chemical over a lifespan o 5 chance that probability of a response could be greater than estimated value on experimental data model 0 Sometimes based on the bestestimate instead of 95th con dence limits 0 Doseresponse curve is generally linear only in lowdose region so slope factor holds true only for low doses Determining Equivalent Human Doses Used if animal data are the basis for extrapolation of human dose 1 Assume different species are equallv sensitive to effects of a toxicant if absorb same amount of agent mg in a toxicant per unit of body surface area 2 Assume only in absence of speci c information about equivalent dose for chemical because is proportional to 23 body weight equivalent human dose mgday or massunit time human weight animal weight 6 human close 2 animal close same units x Z If animal doses expressed as mgkg per day then use animal body weight human body weight 4 6 human dose 2 animal close x 2 Animal Inhalation Rates If using animal inhalation experiments to estimate lifetime human risks for partially soluble vapor or gasses D air concentration ppm is generally considered the equivalent dose between species base on equivalent exposure times measured as fractions of a lifespan With inhalation of particulates or completely absorbed gases the amount absorbed per unit of body surface area is equivalent to the equivalent dose between species Veri cation of Slope Factors EPA s Carcinogen Risk Assessment Veri cation Endeavor CRAVE workgroup validates assesses and resolves con icting toxicity values Evaluating Chemicals wo Toxicity Values 1 Always use Rst and slope factors for chemicals if available in IRIS for risk assessment 2 Use of EPAderived toxicity values prevents duplication of effort and ensures consistency among risk assessments SPEA E311 Lecture Notes RoutetoRoute Extrapolations lf toxicity values are not available for all routes of exposure being considered use a qualitative evaluation of the chemical Absence of this chemical should be discussed in Dermal Exposure No Rst or slope factors are available for dermal routes of exposure 0 Can sometimes be evaluated using an oral RfD or oral slope factor General guidance 0 Exposure via dermal routes is express as absorbed doses which are compared to an oral toxicity value that has been adjusted to an absorbed dose Inappropriate to use oral slope factor to evaluate risk associated with dermal exposure to carcinogens such as benzapyrene causes skin cancer through a direct action at point of application Locally active compounds must be evaluated separately by qualitative assessment of risk 0 Arsenic is an exception because skin cancer is developed through a systematic rather than local actions lf information is not acceptable through ECAO then describe effects of chemical qualitatively and discuss implications of absence of chemical from risk assessment in uncertainty section Uncertainties Related to Toxicity Information Toxicity information or many chemicals is limited Varying degrees of uncertainty associated with toxicity values Doseresponse information from effects observed at high doses to predicts adverse health effects that may occur from lowlevel exposure Using doseresponse information from shortterm exposure studies to predict longterm exposures Using doseresponse information from animal studies to predict human effects Using doseresponse information from homogeneous animal populations or healthy human populations to predict general population effects of individuals with a wide range of sensitivities Dioxin Case Study Most toxic member of the dioxin family is 2378 TCDD o 2 3 7 8 TCDD often known simply as TCDD is known for its lethal effects at very low concentrations a millionth of a gram will kill a guinea pig Reasons for its potency are very subtle and are connected with its structural similarity to potent natural hormones o Hormones act in trace amounts as chemical messengers controlling vital processes in the body Accidentally produced contaminant ie TCDD can act as a 39key in the subtle system of trace chemical messengers in the body and can mimic the action of a hormone SPEA E311 Lecture Notes TCDD Lethal Effects 1 Animals die from wasting disease in 26 weeks at levels ranging from lugkg bw to 5000 ugkg bw 2 Immune system damage at similar levels in all animals examined because of damage to the thymus gland which causes changes in cell immunity especially likely in children Damage to other organs such as liver kidney and digestive tract Reproductive effects miscarriage sterility Birth defects including neurological effects Cancer most potent cancer promoter known also evidence of some tumor initiation animal carcinogen 7 Chloracne persistent skin eruption in humans and some animals P P FPquot Exposure Assessment Background amp Introduction 1 Characterize physical setting 2 Identify potentially exposed populations 3 Identify potential exposure pathways 4 Estimate exposure concentrations 5 Estimate chemical intakes De nitions Exposure Contact of an organism with a chemical or physical agent Exposure in quanti ed as the amount of the agent available at the exchange boundaries of the organism ie kin lungs gut and available for absorption Exposure Assessment determination or estimation qual or quant of the magnitude frequency duration and route of exposure Exposure Event incident of contact with a chemical or physical agent An exposure event can be de ned by time ie day hour or by the incident ie eating a single meal of contaminated sh Exposure Pathwav The course a chemical or physical agent takes from a source to an exposed organism An exposure pathway describes a unique mechanism through which an individual or population is exposed to chemical or physical agents at or originating from a site 0 Each exposure pathway includes a source or release from a source an exposure point and an exposure route 0 If the exposure point differs from the source transportexposure medium or media are included Exposure Point a location of potential contact between an organism and a chemical or physical agent Exposure Route The way a chemical or physical agent comes in contact with an organism ie ingestion inhalation dermal contact Contact Rate amount of a medium contacted per unit time or event ie liters of water ingested per day Intake measure of exposure expressed as the mass of a substance in contact with the exchange boundary per unit body weight per unit time chemicalkg body weightday Also known as normalized exposure rate equivalent to administered dose Absorbed Dose assumed to be 100 or 1 for purposes of this class amount of substance penetrating exchange boundaries of an organism after contact SPEA E311 Lecture Notes Calculated from the intake and the absorption ef ciency Usually expressed as the mass of substance absorbed into the body per unit body weight per unit time Equivalent to intake term Administered Dose The mass of a substance given to an organism and in contact with an exchange boundary per unit body weight per unit time Synonymous With term intake Applied Dose amount of a substance given to an organism especially through dermal contact Lifetime Average Daily Intake exposure expressed as mass of a substance contacted per unit body weight per unit time averaged over a lifetime Subchronic Daily Intake SDI exposure expressed as mass of a substance contacted per unit body weight per unit time averaged over a portion of a lifetime 2 weeks 7 years Chronic Dailv Intake CDI exposure expressed as mass of a substance contacted per unit body weight per unit time averaged over a long period of time 7 years to lifespan Components of Exposure Assessment 1 Characterizing Exposure Setting to characterize current population and any potential future populations that may differ under an alternate land use a Assessor characterized the exposure setting with respect to general physical characteristics of the site and population on and near the site 1 Residential 2 Commercialindustrial 3 Recreational b Basic site characteristics 1 Determine of time potentially exposed populations spend in potentially contaminated areas a 8 hours for commercialindustrial 24 hours maximum daily exposure for residential Determine indooroutdoor activities Determine seasonal variability of activities Determine if site may be used by local populations particularly id access to site is not restricted or otherwise limited because of distance for example do children play on site Do residents hike or hunt onsite 5 Identify sitespeci c population characteristics in uencing exposure ie near major commercial or recreational area local population consuming locally caught sh shell sh or agricultural products ii Populations are identi ed and described with respect to those characters that in uence exposure such as location relative to the site activity patterns and presence of sensitive subpopulations 1 Determine current land use and surrounding areas playgrounds parks homes businesses schools industries 2 Some site may have more than 1 land use designation c Physical Environment characterize exposure setting with respect to general physical characteristics of site i Climate temperature precipitation ii Meteorology wind speed amp direction iii Geologic setting location and characterization of underlying strata iv Vegetation no vegetation forested grassy SPEA E311 Lecture Notes v Soil type sandy organic acid base vi Groundwater hydrology depth direction type of ow vii Location and description of surface water type ow rates salinity Potentially Exposed Populations characterize population on or near the site with respect to location relative to the site activity patterns and presence of sensitive subgroups i Determine location of current populations 1 Distance and direction or potentially exposed populations from the site 2 Identify populations closest to or actually living on the site ie greatest potential for exposure 3 Include potentially exposed distant populations such as public water supply consumers and distant consumers of sh or shell sh or agricultural products grown locally 4 Include populations exposed in the future to chemicals that migrated from the site ii Determine future land use 1 Any activities associated with a current land use are likely to be different under an alternate future land use a Ground water is not currently used in the areas as a source of drinking water but is of potable quality future use as drinking water is possible b Could land use itself change in the future ie industrial use could change to residential or recreational purposes 2 Residential land use is most often associated with greatest exposure D generally most conservative choice to make when deciding future alternate land use a May not be justi ed if chance of supporting residential use is exceedingly small 3 Determine possible alternate future land uses based on available information and professional development a City master plans Bureau of Census b Established landuse trends in general area 4 Assume future residential land use if it seems possible based on the evaluation of the available information a If land use if currently industrial but the land is next to residential area it is likely to become residential b If the land use is currently industrial but the land is in a rural setting without projected population growth then it is more likely to become recreational land use 5 At other sites most likely reasonable that land use will not change in the future 6 Include qualitative statement of the likelihood of the future land use occurring iii Identify Subpopulations of Potential Concern a lnclude infants children pregnant and nursing women elderly people and people with chronic illnesses 2 Due to increase risk from chemical exposures and greater sensitivity a Occupational activities b Living in industrial areas 3 Behavior patterns resulting in high exposure SPEA E311 2 Identify Exposure Pathways identify exposure points points of potential contact with the chemical and routes of exposure are identi ed for each exposure pathway Assessor identi es pathways through which previously identi ed populations iv Lecture Notes a Children exposed to dirt b Persons consuming large quantities of locally caught sh or produce 4 Current or past exposures from other sources a Locations of schools day care centers hospitals nursing homes retirement communities residential areas with children important commercial or recreational sheries and major industries potentially involving chemical exposures b Use local census data and consult local public health of cials may be exposed Each exposure pathway describes unique mechanisms through which populations are exposed to chemical at or originating from the site Exposure pathways are identi ed based on consideration of the sources releases types and locations of chemicals at the site like environmental fate including persistence partitioning transport and intermediate transport and locations and activities of the potentially exposed populations Identi cation of Exposure Pathway 1 Approach for identifying potential human exposure pathways describes the course that a chemical or physical agent takes from the source ending with the exposed individual 2 Exposure pathway analysis links source location and type of environmental releases with population locations and activity patterns to determine signi cant pathways of human exposure b Chemical SourceRelease Receiving medium Release mechanism Release source Air Surface water Volatilization Fugitive dust generation Surface runoff Episodic overland ow Groundwater seepage Surface wastes lagoons ponds pits spills Contaminated surface water Contaminated surface soil Contaminated wetlands Leaking drums Contaminated surface soil Waste piles Contaminated surface soil Lagoon over ow Spills leaking containers Contaminated groundwater Groundwater Leaching Surface or buried wastes Contaminated soil Soil Leaching Surface or buried wastes Surface runoff Episodic overland ow Fugitive dust generationdeposition Tracking Contaminated surface soil Lagoon over ow Spills leaking containers Contaminated surface soil Waste piles SPEA E311 Lecture Notes Contaminated surface soil Sediment Surface runoff Surface wastes lagoons Episodic overland ow ponds pits spills Groundwater seepage Contaminated surface soil Leaching Contaminated ground water Surface or buried wastes Contaminated soil Biota Uptake direct contact Contaminated soil ingestion inhalation surface water sediment ground water or air Other biota 3 Exposure Point a Determine potential release sources for a site in the absence of remedial action use all available site descriptions and data from hazard identi cations and risk characterization b Identify potential release mechanisms and receiving media for past current and future releases c Be sure to note any sources and map suspected source areas and the extent of contamination 4 Exposure Route a Evaluate Fate and Transport in Release Media i Evaluate fate and transport to predict future exposures and link sources with currently contaminated media ii Fate and transport analysis is not meant to result in quantitative evaluations but rather to identify media that are receiving or may receive siterelated chemicals 1 What chemicals occur in the sources at the site and in the environments 2 In what media and at what location may they occur in the future b Chemical Fate i Transported converted downstream in water or on suspended sediment or through the atmosphere ii Physical transformation volatilization precipitation iii Chemical transformation photolysis hydrolysis oxidation reduction iv Biological transformation biodegradation v Accumulated in one or more media including receiving media c Site Speci c Characteristics In uencing Fate and Transport i Soil characteristics ie moisture content organic carbon content and cation exchange capacity can great in uence movement of many chemicals ii High water table may increase the probability of chemicals leaching into soil and into groundwater PHYSICALCHEMICAL amp ENVIRONMENTAL FATE PARAMETERS Koc Provides a measure of the extent of chemical partitioning between organic SPEA E311 Kow SOLUBILITY HENRY S LAW CONSTANT VAPOR PRESSURE DIFFUSIVITY Lecture Notes carbon and water at equilibrium The higher the KOC the more likely a chemical is to bind to soil or sediment than to remain in water Provides a soil or sedimentspeci c measure of the extent of chemical partitioning between soil or sediment and water unadjusted for dependence upon organic carbon The higher the Kd the more likely a chemical is to bind to soil or sediment than to remain in water Provides a measure of the extent of chemical partitioning between water and octanol at equilibrium The greater the Kow the more likely a chemical is to partition to octanol than to remain in water Octanol is used as a surrogate for lipids and Kow can be used to predict bioconcentraion in aquatic organisms Upper limit on a chemical s dissolved concentration in water at a speci ed temperature Aqueous concentration in excess of solubility may indicate absorption into sediments the presence of solubilizing chemicals such as solvents or the presence of a non aqueous phase lipid Provides a measure of the extent of chemical partitioning between air and water at equilibrium The higher the Henry s Law Constant the more likely a chemical is to volatize than to remain in water Pressure exerted by a chemical vapor in equilibrium with its solid or liquid form at any given temperature It is used to calculate the rate of volatilization of a pure substance from a surface or in estimating a Henry s Law Constant for chemicals with lower water solubility The higher the vapor pressure the more likely a chemical is to move in response to concentration gradients Describes the movement of a molecule in a liquid or gas medium as a result of differences in concentration Used to calculate the dispersive component of chemical transport The higher the diffusivity the more likely a chemical is SPEA E311 Lecture Notes to move in response to concentration gradients BIOCONCENTRATION FACTOR BCF Provides a measure of the extent of chemical partitioning at equilibrium between a biological medium such as sh or plant tissue and an external medium such as water The higher the BCF the greater the accumulation in living tissue is likely to be MEDIASPECIFIC HALFLIFE Provides a relative measure of the persistence of a chemical in a given medium although actual values can vary greatly depending on sitespeci c conditions The higher the halflife the more persistent a chemical is likely to be What are the principle mechanisms for change or removal in each of the environmental media How does the chemical behave in air water soil and biological media Bioaccumulate Biodegrade Absorbed by plants or other biota Does the agent react with other compounds in the environment Is there intermedia transfer What are the mechanisms for intermedia transfer What are the rates of intermedia transfer or reaction mechanism How long might the chemical remain in each environmental medium How does its concentration change with time in each medium What are the products into which the agent might degrade or change in the environment Are these products potentially of concern Is a steadystate concentration distribution in the environment or in speci c segments of the environment achieved 5 Qualify Exposure a Estimations of Exposure Concentration i Assessor determines the concentration of chemicals that will be contacted over the exposure period ii Concentrations are estimated using monitoring data andor chemical transport and environmental fate models iii Modelling is used to estimate future chemical concentrations in the media that are currently contaminated or that may become contaminated and current concentrations in media andor locations lacking monitoring data b Calculation of Intake Variables CgtltCRgtltEFDgtlt 1 I BW AT Where I intake amount of chemical at the exchange boundary mgkg body weightday SPEA E311 Lecture Notes C chemical concentration average concentration contacted over the exposure period ie mgL water CR contact rate amount of contaminated medium contacted per unite time or event ie litersday EFD exposure frequency and duration describes how long and how often exposure occurs Often calculated using two terms EF and ED EF exposure frequency dayyear ED exposure duration years BW body weight average body weight over the exposure period kg AT averaging time period over which exposure is averaged days I Assessor calculated chemicalspeci c exposure for each exposure pathway identi ed in Step 2 ii Estimates are expressed in terms of the mass of substance in contact with the body per unit body weight per unit time ie mg chemicalkg bodyweightday iii Exposure estimates intakes represent the normalized exposure rate iv Chemical intakes are calculated using equations that include variables for exposure concentration contact rate exposure frequency exposure duration body weight and exposure averaging time v Values of some of these characteristic of potentially exposed populations vi Intakes are estimated and organized by population vii Sources of uncertainty ie variability in analytical data modeling results parameter assumptions and their effect on exposure estimates are evaluated and summarized viii Uncertainty is important to decision makers who must evaluate the results of exposure and risk assessment and make decisions regarding the degree of remediation required at a site ix Summarizes estimated intakes for each pathway evaluated c lPathway Speci c Exposure Reasonable Maximum Exposure RME Reasonable expectation under current and future landuse conditions D highest exposure reasonably expected to occur at a site Estimated for individual pathways If population is exposed through multiple path ways then a combination of exposure pathways are included in the RME Best Professional Judgment BPJ Speci c exposure pathways require BPJ 0 Variables provided as general recommendations 0 Usually estimated for average and upperbound case twocase exposure instead of single exposure for both current and future land use Twocase exposure provides some measure of uncertainty Disadvantages Upperbound may be above range of possible exposures Average estimate is lower than exposures potentially experienced by much of population Intent is to estimate a conservative exposure case well above the average case that is still within the range of possible exposures SPEA E311 Lecture Notes Uncertainty variation in individually exposure variables is used to evaluate uncertainty l clearly identi es contributing variables Exposure Pathway Source and mechanism of chemical release Retention or transport medium or media in cases involving media transfer of chemicals Point of potential human contact with the contaminated medium exposure point Exposure route at the contact point Exposure Assessment pt 3 General Considerations Quantify the magnitude frequency and duration of exposure for the population and exposure pathways 0 An exposure assessment us usually conducted as a twostep process 0 Exposure concentrations are estimated 0 Pathway speci c intakes are quanti ed Quantifying Reasonable Maximum Exposure 0 Exposure is the contact of an organism with a chemical or physical agent 0 Exposure over time total exposure can be divided by the time period of interest to obtain an average exposure rate per unit of time 0 Average exposure rate can be expressed as a function of body weight 0 lntake is he normalized exposure for time and body weight expr4essed as mg chemicalkg body weightday ICgtltCRgtltEFD XL BW AT Three Categories of Variables Chemicalrelated variable exposure concentration 0 Variables describing exposed population contact rate exposure frequency and duration and body weight Assessmentdetermined variable averaging time Each intake variable has a range of values that should result in an estimate of maximum exposure for that pathway maximum exposure reasonably expected to occur at a site Reasonable Maximum Exposure RME Some intake variables may not be at individual maximum but in combination with other variables they may result in estimate of RME Reasonable maximum exposure cannot be based solely on quantitative information it requires best professional judgment BPJ Must consider sitespeci c information or particular needs of the risk manager Exposure Concentration Concentration arithmetic average of the concentration that is contacted over the exposure period SPEA E311 Lecture Notes Concentration does not re ect maximum concentration that could be contacted at any one time It is regarded as a reasonable estimate of concentration likely to be contacted over time Assuming longterm contact with maximum concentration is not reasonable Uncertainty associated with any estimate of exposure concentration should be 95 Cl based on arithmetic average o If low sample numbers then the upper con dence limit on average concentration will be high and possibly above maximum detected or modeled value Use maximum detected or modeled value to estimate exposure concentration Contact Rate Amount of contaminated medium contacted per unit time or event Use 95th percentile value for variable can use 90th percentile is 95th is not available If statistical data are not available BPJ should be used to approximate the 95th percentile value Several separate terms should be used to derive estimate of contact rate 0 Dermal contact estimate exposed skin surface area dermal permeability of a chemical and exposure time Exposure Frequency amp Duration Use reasonable conservative estimates of exposure over time National statistics available at upper bound 90th percentile and average 50th percentile number of years spent by individuals at one residence Values may underestimate actual time that the individual may live in one residence Upper bound of 30 years can be used for exposure duration when calculating reasonable maximum residential exposures may use 70 years as more appropriate assumption If the average contact rate is long term ie daily sh ingestion rate averaged over a year then a daily exposure frequency ie 365 days should be assumed Body Weight Average body weight over the exposure period If exposure occurs only during the childhood years D average child body weight during exposure period should be used to estimate intake Soil ingestion exposure can occur throughout a lifetime but the majority occurs during childhood due to contact rates 0 Calculations are for age groups with similar ratios of contact rate to body weight Lifetime exposure is calculated by taking timeOweighted average of exposure estimates over all age groups Pathways with ratios of contact rate to body weight are fairly constant over a lifetime ie drinking water ingestion 0 Body weight of 70 kg is used Keeping body weight constant reduces error SPEA E311 Lecture Notes Averaging Time Dependent on toxic effect being assessed different mechanisms ofaction produce different toxic effects 0 For exposures to developmental toxicants intakes are averaged over exposure event day or a single exposure incident 0 Acute toxicant intakes are averaged over shortest exposure period that could produce an effect usually an exposure event or a day Longerterm exposure to noncarcinogenic toxicants are averaged over period of exposure subchronic daily intake or lifetime daily intake Discuss uncertainty in both the exposure assessment and risk characterization chapters of risk assessment report Timing Considerations Greatest concern is often longterm chronic exposures at low chemical concentrations Shortterm exposures require 1 Toxicological characteristics of chemical or potential concern 2 Occurrence of high chemical concentration or potential for large release 3 Persistence of the chemicals in the environment 4 Characteristic of the population that in uence the duration of exposure ie elderly children sick Toxicological Considerations Chemicals produce an effect after a single or very shortterm exposure to low concentrations 0 Acute toxicants include skin irritants neurological poisons and developmental toxicants Important to assess exposure for the shortest time period that could cause effect It is usually a single event or single day although multiple exposures over several days can produce effect 0 Developmental toxicants concern is the exposure event a single exposure at the critical time in development is suf cient to produce adverse effect Concentration Consideration Chemicals can produce effect after a single or very shortterm exposure but only if the exposure is to a high concentration 0 Need to identify situations with shortterm exposure to high concentration ie small but highly contaminated site or potential for large chemical release explosion ruptured drum breached lagoon dike Exposure is based on the shortest period of time that could produce an effect Persistence Considerations Chemicals degrade rapidy Exposures should be assessed only for that period of time in which the chemical is present at the site Exposure assessments in these situations may need if they are persistent or toxic at the levels predicted to occur at the site SPEA E311 Lecture Notes Population Considerations 0 Population activities are shortterm 0 Few weeks to a month 0 Infrequent o Intermittent Seasonal exposures occur during vacations or other recreational activities Periods of time over exposures are averaged depending on toxic effect being assessed Exposure Assessment pt 4 Quanti cation of Exposure Determination of Exposure Concentration General considerations use BPJ to estimate exposure concentrations based on monitoring data or a combination of monitoring data and exposure assessments Direct measure of monitoring data 0 Exposure concentrations are usually estimated with the monitored medium or if monitoring is done at exposure point 0 Summarize available monitoring data 0 Divide chemical data from a particular medium into subgroups based on the location of sample points and potential exposure pathways 0 If monitored at exposure point treat values separately when estimating intakes 0 Use maximum concentration from medium as screening approach to place upper bound on exposure need to modify to more probable exposure condition 0 Use 95 upper con dence interval CI on arithmetic average Modeling Approaches May not be able to use monitor data alone fate and transport models may be required to estimate exposure concentrations 0 Where exposure points are spatially separate from monitoring points 0 Where temporal distribution of data is lacking Where monitoring data are restricted by the limit of quantitation Other Considerations 1 Review spatial distribution of the data and determine relevance of pathways being assessed 2 Consider location of contamination with respect to known or anticipated population activity patterns 3 Map concentration distribution and activity patter for exposure assessment 4 Intersection of activity pattern and contamination de ne exposure area 5 Random grid or systematic grid pattern sampling may be most appropriate for exposure pathway than data collected only from hot spots Required Information Veri ed laboratory data using gas chromatographymass spectrometry GCMS Steadystate versus nonsteadystate conditions cause overestimation of longterm exposure pathways for certain pathways 0 May need to assume steadystate conditions because source depletion rates are not readily available SPEA E311 Lecture Notes 0 Number and type of exposure pathways that must be assumed required information may require sitespeci c parameters that are not availableuse literature to determine I reliable exposure concentrations can be made 0 Number and type of date processes to be considered mass balance dilution dispersion equilibrium partitioning chemical reactions biodegradation and photolysis may be needed Considerations for Estimates of Exposure in Groundwater Use groundwater sampling data as estimates of exposure concentrations when the sampling points correspond to exposure points 0 Samples taken directly from a domestic well or drinking water tap should be interpreted cautiously due to leaching from pipes Monitoring wells data are usually assessed at exposure point 0 Determine if aquifer has suf cient production capacity and is of suf cient quality to support drinking water to other uses 0 Assume water could be drawn from anywhere in the aquifer regardless of location of existing wells relative to the contaminant plume Can assume water might be drawn from directly adjacent to source 0 Compare construction of drinking water wells with monitoring wells may be drawing from multiple aquifers especially if the possess limited hydraulic connec on Filtration of water provides useful information for chemical transport within an aquifer but it may underestimate chemical concentration in an un ltered tap Use un ltered samples to estimate exposure concentrations Groundwater data are of limited use for evaluating longterm exposure concentrations because they are generally representative of current site conditions and not longterm trends 0 Modeling is generally complex due to chemical and physical processes that may affect transport ie leaching advection including ltration ow through unsaturated zone and ow with groundwater dispersion sorption and transformation 0 Ability to dissolve in water versus no aqueous phases oating on top of groundwater or sinking to the bottom of the aquifer Consideration for Estimating Exposure Concentrations in Soil lf assuming that concentrations remain constant over time can use current exposure concentration from monitoring data Assumptions incorrect of leaching volatilization photolysis biodegradations wind erosion and surface runoff will reduce chemical concentration over time Determine if source depletion is likely to occur Assume constant concentration over time and base exposure concentration on monitoring data document your assumption Spatial distribution of data are a critical factor Use for estimating the average concentrations contacted over time if it is assumed that soil is spatially random contact with soil in all areas of the site is equally probable Random sampling programs or samples from evenly spaced grid networks considered as representative of concentrations across the site SPEA E311 Lecture Notes 0 Many monitoring plans characterize only obvious contaminated sites or hot spots 0 Eliminate areas where direct contact is not realistic Contamination may be unevenly distributed across a site hot spots Exposure to a hot spot should be estimated separately due to site or population characteristics Consideration for Estimating Exposure Concentration in Air Three general approaches 1 Ambient air monitoring 2 Emission measurements coupled with dispersion modeling 3 Emission modeling coupled with dispersion modeling Longterm exposures are based on longOterm averages Shortterm exposures measured or modeled peak concentrations may be most representative Considerations 1 Appropriate data for the exposure being addressed 2 No signi cant analytical problems affect the data background levels are not signi cantly higher than potential siterelated levels and siterelated levels are not below the instrument detection limits 3 May still be uncertainties due to unrepresentative longterm average air concentrations 4 Few sampling periods collected during one meteorological or climatic condition source of chemical changes over time 5 Use models to predict rate at which chemicals may be released into the air from a source and use dispersion models that predict associated concentration in air at potential receptor points Outdoor Air Modeling Volatilization of chemicals may result from contaminated media or as a result of the suspension of onsite soils 0 Models predicting emission rates for volatile chemical or dust require numerous input parameters many are sitespeci c Emission due to suspension of soils may result from wind erosion or exposed soil particles and from vehicular disturbance of soil Dispersion model can be applies to estimate air concentrations at receptor points including type of source and location of receptor relative to source Indoor Air Modeling lndoor emissions result from transport of outdoor generated dust or vapor indoors or volatilization of chemicals indoors during use of contaminated water Few models predict indoor concentrations from outdoor sources Dust transport is assumed to be less indoors than outdoors vapor transport indoors can be assumed to be equivalent to vapor transport outdoors however if subsurface soil gas concentrations indoors could exceed outdoor concentrations Vapor use indoors may be greater than outdoors depending on emission source characteristic dispersion indoors and indooroutdoor air exchange rate Considerations for Estimating Exposure Concentrations in Surface Water Use sampling points that corresponds to exposure points 1 Where shing or recreation activities take place SPEA E311 Lecture Notes 2 At intake to drinking water supply Can be used to estimate exposure concentration Limitations of SurfaceWater Monitoring Data 1 Temporal representativeness a Seasonal changes in ow temperature and depth signi cantly affect the fate and transport of contaminants b Releases depend on storm conditions that produce surface runoff and soil erosion c Lakes feature seasonal strati cation and change in biological activity d Monitoring data may not represent longterm average concentrations or shortterm concentration after storm events 2 Spatial representativeness a Variation in concentration can occur with respect to depth and lateral locations in surface water bodies b Sample locations must consider mixing zones c Concentrations within mixing zones may be considerably higher than at downstream points where mixing has already occurred 3 Quantitation Limit a Large surfacewater bodies may have groundwater discharge or runoff from relatively small areas that can be signi cantly diluted b Standard analytical methods may not be able to detect chemicals at dilute levels c Toxic potential to bioaccumulate may require assessment of concentrations 4 Contribution from other sources a Normally subject to contamination from any sources b Chemicals associated with offsite sources may be dif cult to distinguish from onsite chemicals Consideration for Estimating Exposure Concentrations in Sediments Sediment monitoring data are expected to provide better temporal representativeness than surface water concentrations Especially true for PCBs PAHs and some inorganic chemical ie metals that will remain bound to sediments D When using monitoring data to represent exposure concentrations for directcontact exposures data from surficial nearshore sediments are required Considerations for Estimating Chemical Concentrations in Food Fish amp Shell sh can be measured or estimated but must be adequate to characterize population and species of concern In absence of tissue concentrations determine whether chemical bioconcentrates matter taken up from water or bioaccumulate matter taken up from food sediment and water Lowmolecular weight organic chemicals do not bioaccumulate in aquatic organisms to a great extent 0 The accumulation of chemicals varies from one species to the next 0 Use bioconcentraion fact BCF organismwater partition coef cient to estimate steadystate concentrations SPEA E311 Lecture Notes BCF estimates of concentrations in edible tissue are more appropriate for human exposures from sh or shell sh ingestion than those estimates from whole body although this is not applicable to all aquatic species or all human populations Plants Siterelated chemicals may be present in plants due to deposition onto plant surfaces 0 Uptake from soil andor 0 Uptake from air 0 Use plant or plant products to estimate exposure concentrations 0 Using models can introduce substantial uncertainty into exposure assessments Deposition as source air deposition models use with plant interception fraction to estimate uptake 0 Plant interception fraction can be developed for a speci c crop be considering crop yield and the surface area of the plant available for depositions Soil contamination as source calculate concentration in plants by multiplying soil to plant partition coef cients by soil concentrations 0 Based on eld or laboratory experiments applicable to vegetation or crop of concern o If partition coef cient is absent for speci c crop use general BCFs in literature that are not cropspeci c o Sitespeci c factors affect uptake ie pH organic content of soil and presence of other chemicals Terrestrial animals use tissue monitoring data for estimating human exposure 0 ln absence of tissue data use transfer coef cients together with total chemical mass ingested by an animal per day to estimate contaminant concentration in meat eggs or milk 0 Generally tissue data is not available for bird but is for some mammals Cattle are exposed to water soil corn silage pasture grass and hay each contains different concentration based on daily mass of chemicals ingested per day 0 Transfer coef cients Ng et al 1977 1979 1982 0 Calculate directly from feeding studies 0 Can use regression equations in the literature for the estimation of transfer coef cients 0 Regression equations using feeding studies from shortterm exposures may underestimate meat or milk concentrations 0 Regression equations rely on Kow and may overestimate exposures to rapidly metabolize chemicals 0 Estimate daily dose from amount of feed soil and water ingested by dairy and beef cows and combine with chemical concentration is these media Rules for Bioconcentraion Factors BCFs When data from multiple experiments are available select BCFs from tests using species most similar to species of concern at the site Multiple BCF directly by the dissolved chemical concentration SPEA E311 Lecture Notes Be sure the BCF study is from steadystate or equilibrium conditions from longterm exposure Shortterm chemical concentrations may overestimate tissue levels in sh exposed for less time No BCFs Estimate BCF with a regression equation based on octanowater partition coef encts Kow Several equations are available from literature use structurally similar chemicals over general equations Regression equations can over or underestimate concentration in sh tissue depending on the chemical of concern High molecular weight PAHs with high Kow values predict high sh tissue residues PAHs are rapidly metabolized in the liver and do not appear to accumulate signi cantly in sh Regression equations cannot account for pharmokinetics and can overestimate bioconcentrations Literature Not Available Consider equations for estimating uptake in whole plants into the root and translocation from the root into aboveground parts Requires physicalchemical parameter such as Kow or molecular weight which were developed using a limited database Use caution in applying any partition coef cient Final Process in First Step Summarize exposure concentrations derived for each pathway Exposure Assessment pt 5 Quanti cation of Exposure Purpose Methodology for calculating chemical speci c intakes for the population and exposure pathways selected for quantitative evaluation 0 Use general intake equation with modi cation Expressed as amount of chemical at the exchange boundary ie kin lungs gut available for absorption lntake is not equivalent to chemical absorbed into the bloodstream Example Standard Equations for Estimating Human Intakes Values for equations and examples presented for residential exposures Pathwayspeci c variable values for population other than residential Upperbound 95th percentile or maximum values Carcinogenic chronic value is 70 years lifetime 0 convert into days to use as averaging time in equation 0 Noncarcinogenic chronic anything greater than 10 of lifetime value is 7 years lifetime 0 convert into days to use as averaging time in equation Average mean or median Calculate RME reasonable maximum exposure Groundwater and surface water Soil sediment and dust intakes SPEA E311 Lecture Notes 9 Air intakes 9 Food intakes 9 Combining chemical intakes across pathways 9 Evaluating uncertainty Groundwater and Surface Water Chemicals of concern in groundwater and surface water through various routes Ingestion of groundwater or surface water used as drinking water Incidental ingestion of surface water while swimming Dermal contact with groundwater or surface water inhalation from volatilized surface or groundwater covered in air intakes Intake from Drinking Water 0 Residential intakes from ingestion of drinking water or surface water 0 Based on un ltered water samples Ingestion rates IRs could be lower for residents who spend portion of day outside home 0 Exposure frequency EF may vary with land use 0 Recreational users and workers exposed less than residents pg 126 RAGS Intake from Ingestion of Surface Water While Swimming Incidental ingestion while swimming 0 Chemical concentration CW should represent un ltered samples 0Incidental ingestion rates IRs not found in literature EPA recommends using 50mLhr for swimming 0Exposure duration ED will generally be less for recreation users of surface water than residents oWorkers not expected to be exposed to this pathway pg 127 RAGS Intake from Dermal Contact Intake from dermal contact with water while swimming wading or household use bathing calculated exposure is actually the absorbed dose not the amount of chemical that comes in contact with the skin ie intake Permeability constant PCs re ect movement of chemical across skin to stratum comeum and into bloodstream 0 Use octanol water partitioning coef cient Kow Record in summary of exposure assessment results so that calculated intake is compared to appropriate toxicity reference value in risk characterization chapter PC equilibrium partitioning and likely overestimates absorbed dose over short exposure periods ie lt1 hour Permeability of water can be used to derive default value Blank et al 1984 which may underestimate dermal permeability for some organic chemicals SPEA E311 Lecture Notes Reasonable Maximum Exposure 50th percentile values instead of 95th percentile values are used for the area of exposed skin SA D surface area and body weight are strongly correlated and 50th percentile representative of surface area of individuals of average weight Le 70 kg Estimates are conservative due to conservative estimates of dermal absorption PC and exposure frequency and duration SA will vary with activity and amount of clothing worn 0 Greater skin surface area is in contact with water while bathing or swimming than while wading o Worker exposure depends on type of work protective clothing worn and extent of water use and contact Soil Sediment and Dust Intake Individuals exposed by routes 1 Incidental ingestion 2 Dermal contact Incidental ingestion population characteristic in uence variable values Exposure Duration ED may be less for workers and recreational users Considerations Ingestion rates IRs for children younger than 8 are based on fecal tracer studies and include indoor dust and outdoor soil Values are representative of longterm average daily ingestion rates for children and are used in conjunction with exposure frequency of 365 daysyear Fraction of dust or soil contaminated FI Indoor dust can be equal to outdoor soil FI 10 Ingestion of sediment can use the same equations as ingestion of soil Ingestion of sediments is not relevant pathway for industrialcommercial land use exception workers repairing doclt5 Dermal Contact Calculation of exposure is estimate of absorbed dose and not the amount of chemical in contact with the skin intake Absorbed factors ABS re ect description of chemical from soil and absorption of chemical across the skin into the bloodstream 0 Use 50th percentile body surface area SA to estimate contact rates 0 SA and body weight show strong correlation Contact rates may vary with time of year and may be greatest for Individuals contacting soil in the warmer months of the year when less clothing is worn Review literature for other soil types and other body parts using sitespeci c information and BPJ SPEA E311 Lecture Notes Considerations Best guess for children potentially in risk assessment is for fall amp spring days gt32F and for summer or when not attending school Indoor dust outdoor soil EF 365 daysyear EF and EF may be lower for workers and recreational users depends on type of activity at the site Use same equations for soil and sediment Adherence for sandy sediments less than soil because contact with water may wash sediment off skin Exposure frequency for sediments is probably lower than for soils at many sites Air lnta ke Routes of exposure USE EPA EXPOSURE HANDBOOK Inhalation of chemical in the vapor phase Absorbed to particulates Dermal absorption of vapor phase chemicals in considered lower than inhalation in many instances and usually ignored Expressed as mgkgday Combined inhalation intakes with inhalation Rst concentration units mgm3 Inhalation of VaporPhase Chemicals Consider variations with land use Exposure time ET is less for worker and recreational users For exposures lt 24 hoursday an hourly inhalation rate IR based on activity age and sex should be used instead of the daily IR values Exposure duration ED may be less for workers and recreational users Inhalation of ParticulatePhase Chemicals Calculate based on modi ed equations Derive inhalation estimates using particulate concentration in air the fraction of particulate that is respirable ie particles lt 10 um size and concentration of chemical in respirable fraction Adjust intakes of particulatephase chemicals if combined with toxicity values based on exposure to chemicals in vapor phase done in risk assessment step Food Intake Ingestion of chemicals accumulated in food food items of concern 0 Fish amp Shell sh Vegetables and other produce 0 Meat eggs and dairy products domestic and game species Ingestion of Fish and Shell sh Exposure depends on availability of suitable shing areas SPEA E311 Lecture Notes Chemical concentration in sh or shell sh CF should re ect edible tissues when available Edible tissues vary with aquatic species and population eating habits Residents near major commercial or recreational sheries of shell sheries ingest larger quantities of locally caught harvest than inland residents Workers are not likely to be exposed although at some sites exposure may be possible Ingestion of Vegetables or Other Produce Signi cant for farmers and ruraland urban residents consuming homegrown fruits and vegetables Contaminated backyard gardens Fraction of food ingested that is contaminated Fl can be estimated using fraction of fruits or vegetables consumed daily that is home grown HF EPA values HF fruit 020 average 030 worst case HF vegetables 025 average 040 worst case Worst case 95 values Pao et al 1982 provides speci c fruits and vegetables Workers not likely to be exposure via path way exposure for recreational users is negligible Ingestion of Meat Eggs and Dairy Products Rural residents may consume poultry livestock and wild game exposed to contaminants at site Fraction of contaminated food ingested daily Fl can be estimated for beef and dairy products based on the fraction of these foods that are homegrown 0 HF beef 040 average 075 worst case 0 HF dairy 040 average 075 worst case 0 Worst case 95 values Workers not likely to be exposed via this path way Exposure duration ED and exposure frequency EF likely to be less for recreational users ie hunters Combining Chemical Intake across Pathways Reasonable maximum exposure RME re ects site pathways individually and across all pathways Population can be exposed across several exposure routes Combining RME required average variable values identi ed in previous sections to calculate intakes for typical exposures At this point in assessment estimated intakes are not summed across pathways addressed in risk characterization chapter Assessor should organize results of previous exposure analysis by grouping all applicable exposure pathways for each exposed population Enables risk from appropriate exposures to be combined SPEAE311 Lecture Notes Evaluating Uncertainty Assessor evaluates sources and degree of uncertainty associated with estimates of exposure to determine if exposure estimates are RME Separated into two parts 1 Tabular summary of values used to estimate exposure and the range of these values 2 Include for each variable the range of possible values and the midpoint of range values used to estimate exposure Include brief explanation of selection rationale Summarize Note major assumptions of exposure assessment 0 Discuss uncertainty associated with each 0 Describe how uncertainty is expected to affect the estimate of exposure Sources of uncertainty 0 Monitoring data 0 Exposure models 0 Values of intake variables Summarizing Exposure Assessment Results Prepare results in tabular format Estimate chemicalspeci c intakes for each pathway Group pathways by population so risk can be combined across pathways Group by current and future use Subchronic and chronic daily intakes should be summarized separately Provided sample calculations for each pathway to enable review of calculations P P PWN Risk Characterization Review of Outputs Most sites involve evaluation of more than a single chemical of concern and might include both carcinogenic and noncarcinogenic substances Gather review compare and organize the results of the exposure assessment Steps in Risk Characterization 1 Organize outputs of Exposure and Toxicity Assessments 2 Quantify Pathway Risks for each Substance a Estimate cancer risk b Estimate noncancer hazard quotient Combine Risks Across Pathways that affect the same individuals Assess and present Uncertainty Consider sitespeci c health or exposure studies Summarize results of the Baseline risk assessment Gather and Organize Information Check to be sure that for each exposure pathway and land use evaluated in the exposure assessment the following information is included P P FPquot Estimate intakes chronic subchronic and shorterterm as appropriate for chemicals SPEA E311 Lecture Notes 0 Important exposure modeling assumptions including 0 Chemical concentration at the exposure points 0 Frequency and duration of exposure 0 Absorption assumption and 0 Characterization of uncertainties List of which exposure pathways can reasonably contribute to the exposure of the same individuals over the same time period For each chemical or substance check to be sure that the following information is included Slope factor for all carcinogenic chemicals 0 Discussion of weight of evidence and classi cation for all carcinogenic chemicals 0 Type of cancer for class A carcinogens Chronic and subchronic Rst and shorterterm toxicity values if appropriate for all chemicals including carcinogens and developmental toxicants Critical effect associated with each RfD Discussion of uncertainty factors and modifying factor used in deriving each RfD and 39degree of con dence in RfD ie high medium low Pharmacokinetic data that may affect the extrapolation from animals to humans for both the RfD and slope factor Uncertainties in any routetoroute extrapolations Consistency and Validity check 0 Check key assumptions common to exposure and toxicity outputs for each contaminant and exposure pathway concern Assumptions 0 Averaging period for exposure 0 Exposure route 0 Absorption adjustments 0 Ensure that the exposure estimates correspond as closely as possible with the assumptions used in developing the toxicity values Averaging Period for Exposure o If toxicity value is based on average lifetime exposure ie slope factors then the exposure duration must also be expressed in those terms 0 For estimating cancer risk always use average lifetime exposure convert lessthanlifetime values to equivalent lifetime values 0 For evaluating noncarcinogens of lessthanlifetime exposures do not compare chronic Rst to shortterm exposure estimates do not convert shortterm exposure estimates to equivalent lifetime values to compare with the chronic Rst 0 Instead use subchronic 0r shorterterm toxicity values to evaluate shortterm exposures Check that estimated exposure duration is similar to the duration of the exposure in the study used to identify the toxicity value to be protective of human health especially for subchronic and shorterterm effects SPEA E311 Lecture Notes 0 In the absence of shortterm toxicity values chronic RfD may be used as an initial screening value ie if the ratio of the shortterm exposure value to the chronic RfD is less than 2 concern for potential adverse health effects if low 0 If the ratio gt 1 then more appropriate shortterm toxicity values are needed to con rm the existence of a signi cant health threat Exposure Route Check that all toxicity values used for each exposure pathway being evaluated are consistent with the route of exposure oral to oral inhalation to inhalation It is not possible to extrapolate between exposure routes for some substances that produce localized effects depending on the route of exposure Dermal exposure absorption is most variable Absorption Adjustment Check exposure estimates and toxicity values to be sure that both are expressed as absorbed doses or both are expressed as intakes ie administered doses 0 Except for dermal route of exposure estimates developed should be as intakes with no adjustments for absorption Three types of absorption adjustments 1 Dermal exposures 2 Absorbeddoses toxicity values 3 Adjustment for medium exposure Dermal Exposure Output of exposure assessment for dermal exposure is expressed as the amount of substance absorbed per kg body weight per day Necessary to derive an absorbed dose toxicity value from an administereddose value to compare With the exposure estimate AbsorbedDose Toxicity Value Substance toxicity values expressed as absorbed rather than administered dose inhalation slope factor in IRIS should express exposure as an absorbed dose rather than as an intake Adjustment for Medium of Exposure Adjusting for different absorption ef ciencies based on medium of exposure ie food soil or water for oral exposure water or particulates for inhalation exposure is occasionally appropriate but it is not generally recommended 0 Many RfD oral and slope factor values assume ingestion in water even when based on studies that employed administration in oil The unadjusted toxicity value provides a reasonable or conservative estimate of risk SPEA E311 Lecture Notes Quantifying Risk Calculating Risks for Individual Substances Carcinogenic Effects Risks estimated as incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen May be suf cient information on mechanism of action that the approach can be modi ed Slope factor SF converts estimated daily intakes averaged over a lifetime of exposure directly to incremental risk of an individual developing cancer Relatively low intakes are likely from environmental exposures from Superfund sites generally assumed that doseresponse relationships are linear in the low dose portion of the multistage model doseresponse curve Slope factor is a constant and risk will be directly related to intake Liner form of the carcinogenic risk equation is applicable Linear LowDose Cancer Risk Equation Risk 2 CDI gtlt SF Where Risk a unitless probability ie 2 x 10quot3 of an individual developing cancer CDI chronic daily intake averaged over 70 years mgkgday SF slope factor expressed in mgkgday391 OneHit Equation for High Carcinogenic Risk Levels Risk1gtlt exp CDIgtlt SF Where Risk a unitless probability ie 2 x 10quot3 of an individual developing cancer CDI chronic daily intake averaged over 70 years mgkgday exp the exponential Slope Factor Considerations Slope factor is often an upper95th percentile con dence limit of the probability of response based on experimental animal data used in the multistage model Carcinogenic risk estimate will generally be an upperbound estimate EPA is reasonably con dent that the 39true risk does not exceed the risk estimate derived through the use of this model and is likely to be less than predicted Quantifying Risk Noncarcinogenic effects 0 Potential for noncarcinogenic toxicity to occur in an individual is not expressed as the probability of an individual suffering an adverse effect EPA does not use a probabilistic approach to estimate the potential noncarcinogenic health effects Evaluated by comparing exposure level over a speci ed time periods ie lifetime with a reference dose derived for a similar exposure period Ratio of exposure to toxicity is called a hazard quotient SPEA E311 Lecture Notes 0 Assumes that there is a level of exposure ie RfD below which it is unlikely for even sensitive populations to experience adverse health effects 0 If the exposure level E exceeds this threshold ie if ERfD gt 1 there may be concern for potential noncancer effects 0 The greater the value of ERfD above 1 the greater the level of concern 0 These are not statistical probabilities o Emphasize that the level of concern does not increase linearly as the RfD is approached or exceeded 0 Rst do not have equal accuracy or precision and are not based on the same severity of toxic effect 0 Slopes of the doseresponse curve in excess of the RfD can range widely depending on the substance Noncancer Hazard Quotient HQElRfD Where E exposure level or intake RfD reference dose E and RfD are expressed in same units Three Exposure Durations 1 Chronic 7 years to lifetime always a concern 2 Subchronic 2 weeks to 7 years schools job sites 3 Shorter term 2 weeks or less occasionally of concern ie for recreational users select behaviors Aggregate Risks for Multiple Substances Need to assess potential health effects of more than a single chemical Estimating risk or hazard potential by considering one chemical at a time may signi cantly underestimate the risks associated with simultaneous exposure to several substances Differs for carcinogenic and noncarcinogenic effects Both assume dose additivity in the absence of speci c mixtures o Dif cult to monitor 0 Data often lacking 0 Note if data are available on the mixtures present at the site in the assumptions documentation Carcinogenic Effects Hazard Index Estimates of incremental individual lifetime cancer risk for simultaneous exposure Cancer Risk Equation for Multiple Substances RiskTZ Risk Where RiskT the total cancer risk expressed as a unitless probability Riski the risk estimate for the ith substance SPEA E311 Lecture Notes Considerations Approximations of the precise equation represents and approximation for combing risks Accounts forjoint probabilities of the same individual developing cancer as a consequence of exposure to two or more carcinogens Differences in equations are negligible for total cancer risk less than 01 Risk summation technique assumes that intakes of individual substances are small Assume independence of action by the compounds involved no synergistic or antagonistic chemical interaction and all chemicals produce same effect cancer If assumptions are incorrect then over or underestimation of actual multiple substance risk could result Calculate separate total cancer risk for each exposure pathway by summing the substancespeci c cancer risks Resulting cancer risk estimates should be expressed using a single signi cant gure Total cancer risk for each pathway individual exposure numbers for all chemicals within a given route should not exceed 1 Limitations Each slope factor is an upper95th percentile of probability distributions that are not strictly additive o If one or two carcinogens drive the risk then not a concern 0 the total cancer risk estimates might become arti cially more conservation as risks are summed from a number of carcinogens Substances with different weights of evidence for human carcinogenicity are included Cancer risk equation for multiple substances sums all carcinogens equally giving similar weight to class B or C as to class A carcinogens Slope factors derived from animals data will be given the same weight as slope factors derived from human data Actions of two different carcinogens may not be independent Uncertainty Assessment amp Presentation of Uncertainty Purpose Not fully probabilistic Conditional estimates given considerable number of assumptions about exposure and toxicity based on future land use Need to fully specify assumptions and uncertainties inherent to risk assessment to put in proper perspective Identify areas where a moderate amount of additional data collection might signi cantly improve the basis for selection of a remedial alternative High quality statistical uncertainty analysis is not practical or necessary 0 Resource requirements to collect and analyze site data as valid probability distributions SPEA E311 Lecture Notes 0 Uncertainty about numerical results if generally large order of magnitude or greater 0 More important to identify key siterelated variables and assumptions that contribute most to uncertainty rather than precisely quantify the degree of uncertainty Categories of Uncertainty lnitial selection of substances used to characterize exposures and risk on the basis of sampling data and available toxicity information Toxicity values inherent for each substance used to characterize risk 0 Exposure assessment inherent in individual substances and individual exposures based on chemical monitoring and population intake parameters 0 Multiple pathwavs incorporated based on exposures to several substances across summed pathways Identify amp Evaluate SiteSpeci c Uncertainty Factors Typically include sitespeci c uncertainties Several sources requiring attention De nition of the physical setting Model applicability and assumptions Transport fate and exposure parameter values Tracking uncertainty and magni cation through various steps of assessment Physical Setting Requires many profession judgments and assumptions 0 De nition of current and future land uses 0 Identi cation of possible exposure pathways now and in the future 0 Selection of substances detected at the site to include quantitative risk assessment Likelihood of exposure pathway and land uses actually occurring Conditional on the existence of the exposure conditions analyzed 0 Need to provide likelihood that assumed conditions will occur to allow interpretation of a conditional risk estimate 0 Provide scoping information ie institutional land use landuse controls zoning regional development plants Chemicals not included 0 Notes missing information on health effects or lack of quantitation in the chemical analysis 0 Chemical with known health effects were eliminated from risk assessment on the basis of concentration or frequency of detection requires doublecheck to ensure proper inclusion Chemical detected at the site but not included in the quantitative risk assessment due to data limitations require discussion about why they are excluded Model Applicability and Assumptions How well does the exposure model approximate the true relationships between site speci c environmental conditions A fully validated model that accounts for all SPEA E311 Lecture Notes known complexities in parameter interrelationships for each assessment is the ideal goal Only simple partially validated models are available and commonly used 0 Need to identify key model assumptions ie linearity homogeneity steady state conditions equilibrium and potential impact on risk estimates 0 In the absence of eld data use limited sensitivity analysis by varying assumptions about functional relationships to indicate magnitude of uncertainty associated with model 0 At a minimum list key model assumptions and indicate the potential impact of each on risk with respect to both direction and magnitude Parameter Value Uncertainty Numerous parameter values are include dint he calculations of chemical fate and transport and human intake 0 Determine key parameters in uencing risk 0 Driving chemicals can be determined by varying the values of parameters suspected and the degree that change in input values change risk estimates 0 Signi cant site data gaps may have required that certain parameter values are assumed for risk assessment ie no information on frequency of swimming in nearby stream or frequency and duration based on national average Siqni cant data uncertainties are other parameters such as whether available soil concentration measurements are representative of true distribution of soil concentration measurements are representative of true distribution of soil contaminant concentrations available Tracking Uncertainty Carrying the risk assessment uncertainty associated with each parameter to characterize the uncertainty associated with the nal risk estimates is the ideal goal A more practical approach is to determine how uncertainties might be magni ed of biased through the risk model Quantitative Approach Used on rare occasions usually not practical or affordable Need to involve a statistician in design and interpretation of the quantitative analysis 0 May be appropriate if exposure models are simple and key input parameter values are available 0 Use analytic method ie Monte Carlo simulation with few parameters with known distributions and linear relationships Semiquantitative Approach 0 Insuf cient data to describe distributions but the data are suf cient to describe potential range of values that the parameter might assume 0 Sensitivity analysis is used to identify in uential model input variables and to develop bound on the distribution of exposure or risk 0 Sensitivity analysis can estimate the range of exposures or risk from combinations of minimum and maximum values for some parameters and midrange values for others 0 Present the ranges of exposure or risk generated by the sensitivity analysis by describing the limitations of the data used to estimate plausible ranges of model input variables SPEA E311 Lecture Notes Qualitative Approach Often most practical given use of information 0 Develop a quantitative or qualitative description of uncertainty for each parameter and simply indicate possible in uence on nal risk estimates 0 Use graphical presentation of results for the signi cance of various assumptions IdentifyEvaluate Toxicity Assessment Uncertainty Factors Summarize uncertainty inherent in toxicity values for duration of exposure for cancer risk and noncancer hazard indices Summarize information ie weight of evidence for potential human carcinogens uncertainty adjustments for noncancer toxicity values MutipieSubstanceExposure Uncertainties Summing risks or hazard indices for several substances is cause for concern because of dose additivity which ignores possible synergism or antagonism among chemicals and assumes similarity of mechanisms and metabolism 0 Data available to assess interactions quantitatively are lacking Carcinogenic risks are treated as additive Noncancer hazard indices are treated as additive o Summarize available synergistic and antagonistic information 0 Discuss how target organ and mechanism of action may be over or underestimates 0 Discussion is particularly important if total hazard index is s 1near unity and effect speci c hazard index is s 1 Site Speci c Studies 0 Compare results of risk assessment to Agency for Toxic Substances and Disease Registry ATSDR health assessments and other sitespeci c studies 0 Review qualitatively the ATSDR for exposure pathways or chemicals of concern that have not been included in the hazard identi cation step 0 Determine why the qualitative conclusions of the health assessment and quantitative conclusions of the baseline risk assessment differ and discuss implications 0 Most sites will not have available data for surrounding populations 0 If epidemiological or other health studies have been conducted include them in the baseline risk assessment 0 Contact the Centers for Disease Control and Prevention and state and local health agencies early 0 Isolated reports of high body levels of substances known to be present might include confounding factors or a signi cant bias 0 Should consider having a professional epidemiologist review and identify possible study limitations and implications for site risk ndings Qualitatively evaluate predictions and observations and describe the study agreements and disagreements Identify factors that might contribute to any disagreement Summarize Risk Information Summarize the risk characterization in a discussion 0 Use tables and gures SPEA E311 Lecture Notes Provide a means of placing the numerical estimates of risk and hazard in the context of what is and is not known about the site and decisions to be made about selection of remedies Key Discussion Point Checklist 1 2 Con dence that the key siterelated contaminant were identi ed and discussion of contaminant concentrations relative to background concentration ranges A description of the various types of cancer and other health risks present at the site ie liver toxicity neurotoxicity distinguishing between known effects in humans and those that are predicted to occur based on animal experiments Level of con dence in the quantitative toxicity information used to estimate risks and presentation of qualitative information on the toxicity of substances not included in the quantitative assessment Level of con dence in the exposure estimates for key exposure pathways and related exposure parameter assumptions The magnitude of the cancer risks and noncancer hazard indices relative to the Superfund site remediation goals in the NCP ie the cancer risk range of 1039 4 to 10397 and noncancer hazard index of 10 The major factors driving the site risks ie substances pathways and pathway combinations The major factors reducing the certainty in the results and the signi cance of these uncertainties ie adding risks over several substances and pathways Exposed population characteristics and Comparison with sitespeci c health studies when available Risk Management Fatalities and injuries grouped in time and space Risk assessment The neutral scienti c process of describing the probability and degree of harm Risk management the more political valuebased process of deciding when how and to what degree to control or reduce health and environmental harm Risk communication process of explaining the meaning of risk to the public including the source of the message and the target or recipients of the message 0 Experts government of cials and the lay public view environmental risk in similar terms 0 Perceptions of the lay public are attributed to knowledge about sources of risk and methods used by technical experts to assess risks Risk perception use of perception of cognitive and psychological factors including cultural and social in uences on risk perception 1 Risk means different things to different people 2 People tend to ignore or discount discrete familiar voluntary and low probability risks 3 Feelings of control and opportunities for participation in uence evaluations of the acceptability of risks 4 People evaluate risk as members of a community 5 Trust is an important in uence on risk perception Qualitative Perceptions Affecting Risk Perception Increased Concern Decreased Concern Fatalities and injuries scattered and random SPEA E311 Lecture Notes Unfamiliar Familiar Mechanisms or process not understood Mechanisms or process understood Involuntary Controllable Children speci cally at risk Voluntary Delayed effects Children not speci cally at risk Risk to future generations Immediate effects Identi able victims No risk to future generations Effects dreaded Statistical victims Lack of trust in responsible institutions Effects not dreaded Much media attention Trust in responsible institutions Major and sometimes minor accidents LittIe media attention Inequitable distribution of risk and No major or minor accidents bene ts Unclear bene ts Equitable distribution of risks and bene ts Effects irreversible CIear bene ts Caused by human actions or faiIures Effect reversible Caused by acts of nature or god Cumulative and Integrated Risk Management Congress pushed for an integrated approach to risk management including quotCreative integrated strategies that address multiple environmental media and multiple sources of risks are needed if we are to sustain and strengthen the environmental improvements of risk reduction our nation has attained over the last 25 years Cumulative risk needs to account for risk from multiple sources stressors and routes of exposure and to identify the impacts of those muItipIe risks on different subpopuIations Nonscienti c Pressures Case Study Pesticide Registration Governed by federal Food Drug and Cosmetic Act FDCA to set tolerances or maximum allowable concentration for pesticide residues in food 0 One set of standards for EPA to regulate raw agricultural commodities another stricter standard for processed foods 0 Does not re ect different risks of different products instead re ects political and legal issues in passage of law Political Factors Inordinater slow pace in registering pesticides causes a backlog in assessing the health and ecological effects of pesticides By mid1980 s EPA performed assessments on only 6 of more than 600 active ingredients in pesticides and had not begun testing a majority of the more than 40000 pre1972 pesticides still in use Amendments to Federal Insecticide Fungicide and Rodenticide Act FIFRA passes in 1988 0 Slow pace of EPA could not be attributed to cultural legacy of the EPA s Of ce of Pesticide PoIicy OPP which was in favor of the use of pesticides Political forces impending a reduction in registration backlogs SPEA E311 Lecture Notes 0 FIFRA amendments in 1972 gave agency the insurmountable task of evaluating more than 50000 existing pesticides within 4 years 0 No additional resources to perform the task 0 Agency become defensive and adopted decision rule in opposition to Congress quotRebuttable Presumption against Registration rule Rebuttable Presumption against Registration Rule o If industry could not provide suf cient data or if complaints suggested unreasonable risk the EPA asked industry to marshal evidence rebutting the presumption of risk o If industry could not provide rebuttal no formal toxicity testing took place and the EPA did not register the pesticide If the industry could provide rebuttal no formal toxicity testing took place and the EPA registered the pesticide The EPA privatized some of the testing by assigning it to private laboratories Investigators found that the country s largest testing laboratory falsi ed tests on more than 200 pesticides that the EPA had subsequently registered Technical Complexities Agency lacks data on human effects until a pesticide is used but it also takes years to collect and analyze these data once they are available 0 Political factors further confound the EPA s efforts 0 An example is the economic stakes involved for farmers and manufacturers 0 Media tends to focus of crisis 0 Persistently low levels of funding for pesticide program since its beginning Rea es Pesticide manufacturing was a more than 6 billionyear industry in the 1990 s 0 The EPA experiences strong pressure to keep pesticides in use and little pressure to decertify them 0 Agricultural subsidies often predicated on increasing productivity heavy pesticide use increases productivity and pro t on an acre of land by 20 0 Media focus on crisis causes quotpesticide of the monthquot hysteria followed by congressional hearings followed by diversion of limited resources from long range plans to respond to these pressures EPA experiences a chronic shortfall of funding relative to its responsibilities Toxic Populists Born from substantive disconnect between community concerns and local environmental problems and focus on national issues like climate change 0 Angry vocal and communitybased environmental movements led by concerned workingor middleclass mothers fearing for their families health and safety 0 Associated with anecdotal knowledge of alarming rates of maladies in their neighborhoods 0 They associate these maladies with pollution they see feel smell or ingest from nearby pollution sources or waste facilities in their area 0 Do not dismiss these groups as too amateurish to cause problems 0 May nd lawyers who underestimate the talent of these groups SPEA E311 Lecture Notes Managers who do not understand perspectives and tactics do so at their own peril Groups have been successful institutionalized and professionalized in today s information age so that many of them now have established national legal and technical support networks Three information needs 0 They distrust scienti c enterprise They are suspicious of if not hostile toward traditional scienti c methods They will not be swayed by risk studies alone Place credence in experiential knowledge 0 Place little trust in public health agencies 0 Try to frame issues in moralityplay trends Regulatory Needs Provide opportunities to engage in pollution prevention efforts Reduce risk toxicity exposure Identify and factor in or work to change regulatory drivers standing in the way of riskbased priority setting ie enforcement orders and milestones agreed to before adequate information was available Enhance project acceptability to the public Reduce offsite exposure potential ie groundwater migration plumes Back to the Beginning Detailed analysis of alternatives assess each alternative against speci c evaluation criteria and the results of assessment providing comparisons between alternatives and key tradeoffs Use nine evaluation criteria to address statutory requirements as well as technical and policy considerations in selecting remedial actions Nine Evaluation Criteria PPO P P PPUNE Overall protection of human health and the environment Compliance with ARARs unless they are waived Longterm effectiveness and permanence Reduction of toxicity mobility or volume through the use of treatment Shortterm effectiveness Ease of implementation Cost State acceptance Community acceptance Criteria Categories First two criteria ie overall protectiveness and compliance with ARARs are threshold determinations and must be met before a remedy can be selected 0 Should focus on how speci c alternative achieves protection over time 0 Should note how site risks are reduced Next ve criteria 3 to 7 are primary balancing criteria 0 Important in analysis of effectiveness and permanence involve an evaluation of results of remedial action and residual risk at site after response objectives are met 0 Focus on effectiveness of the controls that will be applied to manage risk posed by treatment residuals or untreated wastes remaining on site including the volume and nature of that material SPEA E311 Lecture Notes 0 Needs to consider what ifremedy fails Criteria 8 and 9 are modifying criteria risk analysis does not factor directly in their analysis Risk Communication What is Risk Communication Risk communication is a combination of messages processes and political situations Consider the following ve scenarios Scenario 1 A large chemical producer in Louisiana issues the information required annually under the Federal Toxic Release Inventory listing the volumes of toxic chemicals it has discharges into the air into the water or on land Meanwhile the Department of Environmental Quality is busy responding to questions about chemical releases Environmental advocates use the information to call attention to the need for stricter controls on the chemical industry Scenario 2 The EPA administrator holds a press conference to assure people that a pesticide known as EDB ethylene dibromide widely used as a fumigant on citrus and grain does not present an immediate health threat despite fears to the contrary He cannot say de nitively what the longterm risks of the chemical are but he promises a thorough study He feels it is necessary to reassure the public in the wake of media reports that he believes overstated the risk Scenario 3 A national newspaper publishes a story about a neighborhood in central California where an unusually high number of children have been diagnosed with cancer Despite careful investigation by health and environmental agencies no environmental cause has been identi ed Some residents support the government s decision to conduct more studies others view he illness as a statistical oddity and fear the local economic effects of more negative publicity Scenario 4 The EPA begins a public information campaign to make the public aware of the risks they may face from concentrations of radon in their homes The goal is to get people to test for radon and to take corrective action if the radon exceeds recommended levels Government experts debate whether the campaign should be designed simply to inform people of the risk or to persuade them to test for radon and take corrective action if needed Scenario 5 A scientist employed by a waste management rm speaks at a community event to share the results of a quantitative risk assessment conducted by the rm According to the expert the risk assessment demonstrates that a waste incinerator the rm wants to build will not pose unacceptable risks The community is divided Some residents want the incinerator for the jobs it will bring others do not trust the company and fear adverse health effects Interpretations of the Scenarios 1 A chemical company releases information required under federal law The information provokes a debate about the health effects of the entire industry SPEA E311 Lecture Notes 2 The most visible environmental of cial in the country tells people that his agency does not know exactly how risky the use of a chemical is in the long run but fears of immediate harm are unfounded His statements are half risk communication and half candid communication of uncertainty 3 A genuine puzzle in the town of McFarland California Of cials cannot explain a disturbing cluster of cancer among the town s children with any apparent environmental cause despite extensive study by experts Residents debate the causes of the illnesses while government experts try to nd an explanation 4 Probably the largest and most systematic public information campaign in EPA s history Much of what is known today about communicating risk came from the radon experience and the research studies associated with it Whether the purpose of the government s radon campaign should have been to inform or in uence illustrates fundamental issues in risk communication 5 Situation is common people across the country have opposed the siting of incineration and other unwanted facilities in their communities Research on risk perception shows that there is more at issue in the disputes than a debate over statistical risk as experts de ne it Distrust and skepticism about expert claims are also factors Risk Communication Early de nition quotan intentional transfer of information designed to respond to public concerns or public needs related to real or perceived hazards Broader de nition quotany public or private communication that informs individuals about the existence nature form severity or acceptability of risks National Academy of Science De nition of quotRisk Communicationquot An interactive process of exchange of information among individuals groups and institutions It involves multiple messages about the nature of risk and other messages not strictly about risk that express concerns opinions or reactions to risk messages or to legal and institutional arrangements for risk management Risk is everywhere 0 People do not always respond to warnings about risk 0 People jaywalk cross against the light trip on loose bricks take medicines that they should not drink alcohol smoke cigarettes and invest foolishly People take a risk even after they have been warned they decide that the bene ts of their acts will likely outweigh the risks Big Debate Policymaker scholars environmental manager in industry and environmental activists have debated topics concerning risk 0 The late 1980s are an era best known as the risk communication decade 0 People have been debating and warning about the risks of technologies chemicals and practices for years c The public became aware of various kinds of risk and started to demand a voice in social and political decisions Foundations of Risk Communication 0 Concept of risk in environmental policy 0 Seen most simply as the possibility of suffering harm SPEA E311 Lecture Notes 0 Expressed as the of adverse effects expected to occur either for every of exposures or per the total population 0 Broken into two main issues harm to human health and harm to ecological resources Origin of Risk Perception Grew out of nuclear power industry s pragmatic and selfinterest efforts to understand why the lay public was so suspicious of its industry Probabilistic risk assessments conducted by the industry had shown nuclear power was a relatively safe technology in which the chance of a serious accident was for all practical purposes zero 0 Why did the lay public not see the world through the same rational eyes as the experts Seven Developmental Phases 1 Prerisk communication view that quotall we have to do is get the numbers rightquot a the task of assessing risk was left to experts who saw no need to share their assumptions methods or even a detailed review of their results with the public b Failed to satisfy popular concerns due to reliance on technical methods rather than the results with the public 2 Primitive stage of risk communication quotall we have to do is tell them the numbersquot a But the problem was that the public usually did not understand or accept the experts numbers as the nal word on the risks they would have to bean 3 quotAll we have to do is explain what we meant by the numbersquot a Researchers and other risk professionals applied themselves to the task of helping people understand probability distributions and other ne points of risk assessment 4 quotAll we have to do is show them that they have accepted similar risks in the pasf a If people could not be convinced of the logic of accepting relatively trivial statistical risks then they should be presented with comparisons to the more common risks they tolerate every day b If they accept the greater risks of driving smoking or eating some naturally occurring carcinogens the risk communicator might say then why not accept the smaller risks of building a waste incinerator in the community c The anecdotal experience of many risk communicators is that such comparisons are as unpopular in practice as they are disingenuous in principle 5 quotAll we have to do is show them that it s a good dealquot a Tried to persuade people of the social and economic bene ts of the risks they were being asked to accept b The problem is that some people bene tted while others bore the risks 6 quotAll we have to do is treat them nicequot a Risk communication expanded to encompass twoway information ows from the lay public to government and experts and back b Re ected willingness to acknowledge the public s concern and the importance of treating people with respect SPEA E311 Lecture Notes 7 quotAll we have to do is make them partnersquot a Became a part of a larger concern with public participation b See major goal as involving the public in risk decisions c View risk communication as a process in which government educates people about sources of risk and their effects while learning about public concerns and perceptions Envision a process allied with emphasis on developing a coproduction environmental ethics in agencies Concerns Should not be surprising that people do not always agree on what risk communication is and what its goals should be o In successful risk communication persuasion transfer of information public participation or empowerment of citizens to make decisions 0 Should it produce an informed citizenry a compliant citizenry and alert citizenry or an empowered citizenry Should the goal be better decisions fairer decisions more consistent decisions or in the throes of environmental gridlock any decision at all Risk Communication Process 0 Source of the message government agencies and industry however environmental advocates community groups scienti c organizations and media play important roles Communicate to ful ll responsibility to protect human health to inform the public of an issue that requires action to stimulate public debate or to respond to claims made by other groups Factors Affecting Process Perceived competence of a source Credibility of individual agencies even though the agencies themselves may have done nothing to earn the public s distrust Trust is a central issue with environmental concerns 0 Organization is competent 0 Organization is unbiased 0 Organization cares about who it serves 0 Organization gives people a fair opportunity to make their views known Design of the Message How to take information based on highly technical quantitative analyses and put in a form that is understandable to the lay public 0 Fine line between technical content and making understandable to public 0 Maintain honesty by conveying technical complexity and uncertainty 0 Present risk in terms that a typical citizen untrained in toxicology risk assessment or statistics may use and act on Issues for message Design As you present issues to an audience present risk information pretty much as your audience members would explain it to each other Poorly received messages were full of technical jargon References has little meaning for the lay public SPEA E311 Lecture Notes Presenter perceived as cold uncaring technicians who talked down to people and worried little about people s needs and concerns Two Thoughts 0 Public possesses inadequate knowledge in scienti c understanding and is unable to think in terms of probabilities or other key aspects or risk 0 Improve public education in scienti c and environmental elds 0 Limits of technical analysis in conveying information clearly 0 Train government of cials and experts to present information effectively before a lay audience 0 Teach them about how to best convey technical information and uncertainty Delivery Channel Faulty assumption that people received information in a state of isolation from other in uences Consider the social political and cultural contexts in which risk information is conveyed 0 Know the community 0 How are citizens likely to perceive government or industry of cials 0 Who are the opinion leaders in a community 0 What organizations or people are likely to have credibility in warning people of risks and in uencing their behavior in ways the reduce risk Which conventional media do people in the community rely on What roles do schools religious organizations and other community groups play in transmitting information and shaping public opinion Target or Recipients Need to convince people of the validity and rationality of the experts risk assessment 0 Need more positive view of laypersons respect need to be a twoway street 0 Public viewed as a source of values and preferences to be consulted not as a problem to be solved 0 De ned as a participatory process mixing bowl of information exchanged issues about risk are debated and public participates with government and technical experts to make decisions Lessons Learned Use simple nontechnical language 0 Use vivid concrete images that communicate on a personal level 0 Avoid distant abstract andor unfeeling language about deaths injuries and iHnesses Acknowledge and respond to emotions that people express such as anxiety fear and outrage Use comparisons to put risks in perspective 0 Include a discussion of actions that under way or that can be taken 0 Tell people what you cannot do EPA s Seven Cardinal Rules of Risk Communication 00 SPEA E311 Lecture Notes
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