Buie, John

Virginia Institute of Marine Science, Wetlands Program

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W&M ScholarWorks Reports 8-1-1996 Methods of Risk Analysis: Traditional and Ecological Approaches John Buie Virginia Institute of Marine Science Virginia Institute of Marine Science, Wetlands Program Follow this and additional works at: https://scholarworks.wm.edu/reports  Part of the Natural Resources and Conservation Commons Recommended Citation Buie, J., & Virginia Institute of Marine Science, Wetlands Program. (1996) Methods of Risk Analysis: Traditional and Ecological Approaches. Wetlands Program Technical Report no. 96-8. Virginia Institute of Marine Science, College of William and Mary. http://dx.doi.org/doi:10.21220/m2-m83f-wp96 This Report is brought to you for free and open access by W&M ScholarWorks. It has been accepted for inclusion in Reports by an authorized administrator of W&M ScholarWorks. For more information, please contact scholarworks@wm.edu. 1Methods of Risk Analysis:Traditional and Ecological Approaches  John BuieIntroductionHistorically, the term risk assessment has beenapplied to the examination of potential risk tohuman health as a result of exposure to someintroduced environmental toxicant. As an intel-lectual discipline, risk assessment is in its in-fancy. Within the past couple of decades, consid-erable research has been done in the fields oftoxicology, industrial hygiene, environmentalimpact assessment, engineering, and epidemiol-ogy. The vast majority of the accessible litera-ture deals with such risk events as radiationexposure as a result of an industrial accident,impact of hazardous material on human health,impact of pesticides on human health, and oilspills. In recent years, a branch of risk analysishas formed that deals primarily with risks posedto the environment as a result of human activ-ity; this type of analysis is generally referred toas ecological risk analysis. This paper sum-marizes the approaches associated with the tra-ditional methods of risk analysis and with eco-logical risk analysis.Traditional Risk AnalysisTraditional risk analysis focuses on the poten-tial impacts to a human population due to thepresence of an introduced substance or event,for example the presence of pesticides in a bodyof water used for human consumption, or an oilspill. A broad variety of techniques are used toevaluate risk in these situations. Risk analysistypically involves four steps: hazard identifica-tion, risk assessment, determining the signifi-cance of the risks, and risk communication. Tra-ditional risk analysis does not typically attemptto address any social or political aspects thatare associated with most risk decisions. Riskanalysis is often used in such activities as haz-ardous waste disposal, use of various riskagents, and selection of sites for potentially haz-ardous facilities. It should be noted that whilemost risk analyses follow similar methodologies,there is no single protocol for determining risk;the required techniques will vary according tothe type of activity in question. For this reason,it is unwise to apply the results of one risk as-sessment to another situation.Hazard IdentificationThe first step in any risk assessment is the de-termination of the existence of a hazard. Thisprocess is not as straightforward as it mightappear. Adverse health effects such as toxicity,carcinogenicity, mutagenicity, and teratogenicityrequire sophisticated laboratory techniques fordetection. The results of such analyses are fre-quently less than clear. Four types of analyticaltools are typically used in hazard determination:epidemiological studies (Lilienfeld and Lilienfeld,1980), in vivo animal bioassays, short-term invitro cell and tissue culture tests, and structure-activity relationship analyses.Epidemiological studies are statistical examina-tions of the patterns of human disease and thefactors that influence those patterns. Epidemi-ology is most useful in situations where, for ex-ample, exposure to risk agents is high, adverse2Wetlands ProgramSchool of Marine ScienceVirginia Institute of Marine ScienceCollege of William and MaryGloucester Point, Virginia 23062Dr. Carl Hershner, Program DirectorMr. Thomas A. Barnard, Jr., EditorDr. Kirk Havens, EditorPublished by: VIMS Publication CenterThis technical report was funded, in part, by theVirginia Coastal Resources Management Program ofthe Dept. of Environmental Quality through Grant#NA47OZ0287-01 of the National Oceanic and At-mospheric Administration, Office ofOcean and Coastal Resources Manage-ment, under the Coastal Zone Manage-ment Act of 1972, as amended.The views expressed herein are those of theauthors and do not necessarily reflect the views ofNOAA or any of its subagencies or DEQ.Commonwealths Declared Policy: to preserve the wet-lands and to prevent their despoliation and destruction...Printed on recycled paper.health effects are distinctive, or when environ-mental levels of the risk agent are relatively high(Cohrssen and Covello, 1989).Frequently, epidemiological data are unavailable.Laboratory studies performed on live animalscan provide information useful to decision mak-ers. Animal bioassay procedures typically fallinto one of three categories: acute exposure tests,subchronic exposure tests, and long-termchronic exposure tests (Cohrssen and Covello,1989). A large number of researchers are involvedin this particular area of hazard identification.For more information on specific laboratory meth-odologies of in vivo animal bioassays, seeTennant, et al, 1987.Cell and tissue culture is used in determinationof substances that may be human mutagens andcarcinogens. However, application of in vitro ge-netic toxicity tests to in vivo carcinogenicity isapparently quite controversial (Cohrssen andCovello, 1989).Structure-Activity Relationship (SAR) Analysisinvolves comparing the molecular structures andproperties of chemicals with unknown hazardsto similar chemicals with known toxicity. Accord-ing to Cohrssen and Covello, 1989, SAR Analy-sis has the most potential for wide applicationand use in the field of chemical hazard identifi-cation.Risk AssessmentRisk assessment attempts to establish the prob-ability and severity of harm to human health and/or the environment resulting from exposure to arisk agent. Numerous procedures are used toeffect risk assessment. Some of these are source/release assessment, exposure assessment, dose-response assessment, and risk characterization.Source/release assessment is most often engi-neering related, as it attempts to determine thelikelihood of the accidental release of some toxinfrom an engineered facility, for example a nuclearpower plant. Other examples of situations whichwould suit this type of assessment include storm-water runoff, leakage from a hazardous wastelandfill, and the release of pathogenic microor-ganisms from a hospital or research facility.Source/release assessment can be quite quanti-tative, involving statistical analyses or modeling.Exposure assessments attempt to estimate ormeasure the quantities of risk agents receivedby a particular population or environment (Davisand Gusman, 1982). Exposure assessments arequite difficult to carry out; humans and otherorganisms engage in behaviors that make it dif-ficult to quantify the duration and/or location ofexposure to the risk agents.Dose-response assessment involves determina-tion of the exact dose of the risk agent receivedby the exposed populations and the relationshipbetween the dosage level and the magnitude ofthe adverse effects. This necessarily requires aninvolved statistical description of the risk agentand its effects. Dose-response methodologies arequite quantitative in nature, and are describedin excruciating detail in almost every article pub-lished in the journal Risk Analysis.Risk characterization is usually the final step ina risk assessment. It is most often a summariz-ing of the data generated in the previous stepswith speculation on potential adverse effects thatwere not included in the risk assessment (alsowith an explanation of why they were excluded).3Examples of some of the numerical risk mea-sures one might find in a risk characterizationare individual lifetime risk, population or soci-etal risk, relative risk, and loss of life expect-ancy.Determination of Significance ofRiskRisk analysis attempts to describe potential riskassociated with a particular activity. Eliminationof all risk is, of course, impossible. There aretrade-offs associated with all risky activities; therisk associated with a particular activity is bal-anced by potential benefits of the activity. At somelevel, decisions must be made regarding what isconsidered acceptable risk. Numerous analyti-cal tools are used to determine and describe ac-ceptable risk (Travis and Hattermer-Frey, 1988).Some of these methods are cost-benefit analy-sis, cost-effectiveness analysis, and decisionanalysis (Von Winterfeldt and Edwards, 1986).Recently, some researchers have described theconcept of de minimis risk: a specified level be-low which a risk estimate is so small that it canbe ignored (Whipple, 1987). None of these ap-proaches is free from criticism, however. In re-cent years, acceptable-risk methodologies havebeen increasingly vilified as being inappropriate(Cohrssen and Covello, 1989). Acceptable-riskdecisions appear particularly vulnerable to criti-cism when high consequence activities are in-volved (e.g., placement of hazardous waste fa-cilities).Risk CommunicationThere are many problems related to the commu-nication of risk probabilities. According toCovello, et al, 1987, these problems include:Message problems: deficiencies in scientific understanding, data,models, and methods resulting in largeuncertainties in risk estimates highly technical risk analyses that are oftenunintelligible to laypersonsSource problems: lack of trust in responsible authorities disagreements among scientific expertsChannel problems: selective and biased media reporting thatemphasizes drama, wrongdoing,disagreements, and conflict premature disclosures of scientific information oversimplifications, distortions, andinaccuracies in interpreting technical riskinformationReceiver problems: inaccurate perceptions of levels of risk strong beliefs and opinions that are resistantto change desire and demand for scientific certainty reluctance to make trade-offs among differenttypes of risks or among risks, costs, andbenefitsIn 1988, the EPA published a set of guidelinesfor effective risk communication (Covello andAllen, 1988). The EPA pointed out that there isno simple method for ensuring effective commu-nication; they also noted that while the guide-lines seem obvious, they are in fact violated fre-quently in practice.Rule 1: Accept and involve the public as a legiti-mate partner.Rule 2: Plan carefully and evaluate performance.Rule 3: Listen to your audience.Rule 4: Be honest, frank, and open.Rule 5: Coordinate and collaborate with othercredible sources.Rule 6: Meet the needs of the media.Rule 7: Speak clearly and with compassion.Ecological Risk AssessmentThe paradigm of traditional risk analysis (singlestresssingle endpoint) has limited applicabil-ity in the field of ecology. Situations which in-volve release of a toxin or pollutant into the envi-ronment might be well-suited to traditional ap-proaches; however many environmental prob-4lems involve multiple stresses that affect manycomponents of an ecosystem. For example, anoil spill poses readily quantifiable risks to hu-man populations, but the problem is more com-plex with respect to the risks face by the affectedecosystem. The task of hazard identificationtakes on a whole new meaning when dealing withglobal climate change; an increase in average glo-bal temperature might favor some species, butadversely affect others.Only the most general of paradigms is availablefor those interested in quantifying ecological risk.Harwell, et al, 1992, described this paradigmas a three-step approach: 1) characterization ofthe stress regime experienced by various com-ponents of the ecosystem; 2) characterization ofhow ecosystems respond to stresses; and 3)characterization of how ecosystems recover fromor adapt to stress.Stress in this sense includes traditional defini-tions of exposure, but also include such factorsas occurrence of nonchemical stress, spatial ex-tent, frequency, intensity, and duration of thestress event, differential intensities of the stresswithin the ecosystem, occurrence of other simul-taneous anthropogenic stresses, and the back-ground natural stresses. Harwell, et al, 1992,listed factors which limit researchers ability topredict ecosystem response to stress events.These include: diversity of ecosystem type diversity of disturbance type differential response of ecosystems to stresses diversity in response according to scale lack of baseline information on ecosystemfunction fundamental limitations in ecological theory environmental variability and stochasticityOne method of dealing with ecological risk is aprioritization methodology described by Harwell,et al, 1992, and in two EPA publications (1987aand 1987b). The authors started with a list ofenvironmental risks found in the EPA publica-tions cited. The EPA list was expanded and modi-fied to include a broad range of environmentalTable 1. Summary of ecological risk rankingsaExtent of stress Medium Recovery timeEnvironmental Stress Biosphere Regional Ecosystem Air Water Terrestrial Short Medium Long1. Global climate HHH HHH HHH HHH XHabitat alteration HH HHH HHH HHH HHH X XStratospheric ozone HHH HHH HHH HHH XBiological depletion HH HHH HH HH X2. Herbicides/pesticides M HH HH HH X3. Toxics in surface waters M HH HH XAcid deposition H H H XAirborne toxics M HH HH HH X4. Nutrients H H XBOD M M XTurbidity M M X5. Oil L M M L XGroundwater L L L X6. Radionuclides L L L XAcid inputs to surface H H XwatersThermal pollution L La From Harwell, et al, 19925risks; the original list suffered from a bias to-ward human health risk. The authors created amatrix of environmental stresses and fundamen-tal ecosystem types. This matrix was intendedto include projections of recovery potential andmagnitude of ecological effects for each ecosys-tem as a function of stress type. A second ma-trix distinguished among risks differentiated byscale (global, regional, or local) and risks differ-entiated by transport mechanism (air, water, orterrestrial). A third matrix related environmen-tal stresses to recovery time frames. The ulti-mate result of all this was an ecological riskprioritization matrix (see Table 1). The authorsnoted with irony that their output matrix didnot match well with public perception of envi-ronmental risks, or even the EPAs own pointsof emphasis (see Table 2).ConclusionTraditional risk analysis deals primarily withthe human health concerns of various anthropo-genic activities. Numerous protocols exist forestimating the human health risk associatedwith various environmental toxins. In contrast,ecological risk analysis attempts to resolve risksto the environment as a result of human activity.It is a much newer field, with few (if any) stan-dard methodologies. Most of the ecological riskanalyses performed place emphasis on activitiesthat have broad scale consequences (e.g., globalclimate change) as opposed to those activitieswhich introduce an environmental contaminantinto a relatively limited area. These conclusionsare often in direct conflict with public percep-tion of environmental risk and with the focus ofthe federal governments own agencies. It seemslikely that ecological risk analysis will become akey element in the future development of envi-ronmental policy at all levels of government.Table 2. Ecological risk priorities vs. public perception of environmentalrisksbHighest ecological risks Public perception of environmental risks global climate change  active hazardous waste sites habitat alteration  abandoned hazardous waste sites stratospheric ozone depletion  water pollution from industrial sources biological depletion  oil spills stratospheric ozone depletionHigher ecological risks  radiation from nuclear power plant accidents herbicides and pesticides  chemicals from industrial accidents radionuclides in nuclear wasteHigh ecological risks  industrial air pollution toxics in surface waters  groundwater contamination from leaking tanks acid deposition  coastal pollution airborne toxics  solid waste water pollution from agricultural runoffMedium ecological risks  water pollution from sewage plants nutrients  vehicular air pollution BOD  global climate change turbidity  wetland habitat alteration acid depositionLow ecological risks  water pollution from urban runoff oil and petroleum products  nonhazardous waste sites groundwater contamination  releases of genetically engineered organisms radionuclides acid inputs to surface waters solid wastes thermal pollutionbFrom Harwell. et al, 1992.6ReferencesCohrssen, J.J. and Covello, V.T., 1989. Risk Analy-sis: A Guide to Principles and Methods for Ana-lyzing Health and Environmental Risks. Wash-ington, D.C.; U.S. Department of Commerce,National Technical Information Service.Covello, V.T. and Allen, F., 1988. Seven CardinalRules of Risk Communication. Washington, D.C.;U.S. Environmental Protection Agency, Office ofPolicy Analysis.Covello, V.T.; Moghissi, A.; and Uppuluri, V.R.R.,1987. Uncertainties in Risk Assessment andRisk Management. New York: Plenum Press.Davis, D.L. and Gusman, S., 1982. Exposure as-sessment introduction, Toxic Substances Jour-nal, 4(1): 4-11.EPA, 1987a. Unfinished business: a comparativeassessment of environmental problems. U.S.Environmental Protection Agency, Office of PolicyAnalysis, Washington, D.C.EPA, 1987a. Unfinished business: a comparativeassessment of environmental problems. Appen-dix III. Ecological risk work group. U.S. Envi-ronmental Protection Agency, Office of PolicyAnalysis, Washington, D.C.Harwell, M.A.; Cooper, W.; and Flaak, R., 1992. Pri-oritizing ecological and human welfare risks fromenvironmental stresses, Environmental Manage-ment, 16(4): 45 1-464.Lilienfeld, A.M. and Lilienfeld, D.E., 1980. Founda-tions of Epidemiology. 2nd ed. New York: Ox-ford University Press.Tennant, R.W.; Margolin, B.H.; Shelby, M.D.; Zeiger,E.; Haseman, J.K.; Spalding, W.; Caspary, M.;Resnick, M.; Stasiewicz, S.; Anderson, B.; andMinor, R., 1987. Prediction of chemicalcarcinogeneticity in rodents from in vitro genetictoxicity assays, Science, 236: 933-941.Travis, C.C. and Hattermeyer-Frey, H.A., 1988. De-termining an acceptable level of risk, Environ-mental Science and Technology, 22(8): 873-876.Von Winterfeldt, D. and Edwards, W., 1986. Deci-sion Analysis in Behavioral Research. New York:Cambridge University Press.Whipple, C., ed., 1987. De Minimis Risk. New York:Plenum Press.

Methods of Risk Analysis: Traditional and Ecological Approaches

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Methods of Risk Analysis: Traditional and Ecological Approaches

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