Advisory Panel on Emerging Contaminants (APEC - PowerPoint Presentation

1. Advisory Panel on Emerging Contaminants (APEC) Risk Assessment 101Jennifer Botsford, MSPHADHS Office of Environmental HealthFebruary 15, 2013

2. OverviewIntroduction Key TerminologyDeveloping NPDWRsMCLs and TTsHealth HazardsSetting MCLGsHealth Advisories and Other Sources of Health Effects Information

3. IntroductionRisk Assessment 101

4. IntroductionRisk Assessment in the Safe Drinking Water Act (SDWA)Establishing public health protection goals Maximum Contaminant Level Goal (MSLG)Estimating and comparing the benefits of risk reduction for regulatory optionsMaximum Contaminant Levels (MCLs) Treatment Technique (TT)

5. What is Risk?

6. What is Risk?

7. What is Safe?Free from harm or riskSecure from threat of danger, harm, or lossZero riskAdapted from: http://ocw.jhsph.edu/courses/EnvironmentalHealth/PDFs/Lecture1.pdf

8. What is Risk?Possibility of loss or injury, perilThe chance of loss; the degree of probability of such lossAdapted from: http://ocw.jhsph.edu/courses/EnvironmentalHealth/PDFs/Lecture1.pdf

9. IntroductionWhat is risk?The probability of injury, disease, or death from exposure to a chemical agent or a mixture of chemicalsEPA definition from IRIS (Integrated Risk Information System)

10. Developing NPDWR’s(National Primary Drinking Water Regulations)Risk Assessment 101

11. National Primary Drinking Water Regulations (NPDWRs)Microorganisms7 standards addressing microorganisms3 bacteria, viruses, 4 indicators (i.e. turbidity)Disinfection Byproducts4 standardsDisinfectants3 standardsInorganic Chemicals16 standardsOrganic Chemicals53 standardsRadionuclides4 standardsCurrently there are 87 legally enforceable standards

12. Key Steps for Developing NPDWRsSetting the MCLGHealth effects informationExposure informationRelevant information and procedures developed by EPA for risk assessment and characterizationAssess whether an MCL or TT is more appropriateIdentify and evaluate costs and effectiveness of treatment alternativesSpecify Best Available Technology (BAT)

13. Key Steps for Developing NPDWRsEvaluate contaminant occurrence Number or systems affectedTo what degree are they affectedEvaluate contaminant exposureNumber of people affected To what degree are they affectedCharacterize compliance choices for regulatory alternatives

14. Key Steps for Developing NPDWRsDevelop multiple MCL (or TT) alternativesCompare benefits and costs; address uncertainty Document the underlying data and analyses to support the proposed or final rule Economic Analysis Health Criteria DocumentOccurrence and Exposure DocumentCost and Technology Document

15. MCL’S and TT’sRisk Assessment 101

16. Maximum Contaminant LevelIs enforceableSet as close to the MCLG as feasible“Feasible” is the level that may be achieved:Best available technology (BAT), treatment techniqueExamination for efficiency under field conditions and not solely under laboratory conditionsTaking cost into considerationRequires a determination as to whether the benefits justify the costs

17. Treatment TechniqueAlternative to an MCL when it is not economically and technologically feasible to ascertain the level of the contaminantCommon for microbiological contaminantsA TT is also an enforceable standard involving a measurable procedure or level of technological performance (e.g. “Action Level”)Surface Water Treatment RuleLead and Copper Rule

18. Health HazardsRisk Assessment 101

19. Health Effects EvaluationComponents of Risk Assessment in RulemakingHazard IdentificationRisk CharacterizationExposure AssessmentDose-Response AssessmentRisk Management: Regulatory Alternatives Development

20. Types of ContaminantsMicrobiologicalWaterborne pathogensBiological toxinsChemicalsNaturally occurringMan-madeUsed in commerce, pesticides Disinfection products and byproducts

21. Identifying Adverse Health EffectsMagnitudeFrequencyRouteDuration of exposureTwo broad categories of health effects:CancerNon-cancer

22. Exposure AssessmentAcute Exposure – Short term exposureChronic Exposure – Long term exposureCritical Periods – Period when an organ/system is most vulnerableRoute of exposure – inhalation, ingestion, dermalCarcinogenicity CategoriesCarcinogenic to HumansLikely to be Carcinogenic to HumansSuggestive Evidence of Carcinogenic PotentialInadequate Information to Assess Carcinogenic PotentialNot Likely to be Carcinogenic to Humans

23. Sensitive PopulationsInfants and children Pound for pound, drink more, eat more, breathe more than adultsDeveloping (i.e. lead)Immature organs may not be able to metabolize/ neutralize contaminantsHabits (i.e. putting objects in mouth, pica)Pregnant women & fetusesDeveloping organsCritical period

24. Sensitive PopulationsElderly peopleBiological changes associated with agingEx. ↓ blood flow  ↓ metabolic rates  ↓ kidney function  ↓ ability to eliminate substances from body Immunocompromised individualsWeakened immune systemDrugs, cancer, transplant patients, HIV/AIDSParticularly sensitive to pathogens, may experience longer or more severe symptomsHighly exposed individualsHigher intake rates (i.e. athlete drinking more water than the average person) Occupational exposures

25. Health Effects EvaluationGastrointestinalNeurologicalHepaticCardiovascular & HematologicalReproductive & DevelopmentalRespiratoryDermatologicalRenal

26. Setting MCLG’sRisk Assessment 101

27. MCLGs: Maximum Contaminant Level GoalsMaximum level of a contaminant in drinking water at which no known or anticipated adverse health effect would occur, and which allows an adequate margin of safety. Do not consider cost and technology.Considerations in setting an MCLG:End-Point – cancer or non-cancerAcute or chronic exposure concernsSensitive populationsData obtained from epidemiological and toxicological studies

28. Toxicological StudiesToxicology – the study of poisons and their actionsToxicological experiments oftenInvolve non-human experimentsInvolve small numbers of animals High exposure dosesUse mathematical models to determine the concentration of the chemical that would cause disease in peopleEPA uses the studies with the greatest margin of safety (overestimation of risk)

29. Toxicological Study MethodsSome animals subjected to high doses of chemicalsNecessary to observe statistically significant rates of diseaseOther animals exposed to lower doses of chemicalsNecessary to provide data inputs for a dose-response curveLong-term carcinogenicity studiesUse these studies together to develop a dose-response curve

30. Strengths and Limitations of Toxicology StudiesEnvironmental Factors, i.e. exposure to contaminants can be controlledContaminant under studyOther exposuresFacilitates interpretation of resultsUncertainty associated with extrapolatingFrom high doses tested to environmentally relevant dosesFrom effects on animals to effects on humans

31. Epidemiological StudiesEpidemiology – the study of how, when, and where diseases occur in populations of humans, and the application of study results to control a public health problemStudies based on human exposureEpidemiologists seek to identify:Risk factors associated with the occurrence of diseaseProtective factors that reduce the risk of disease

32. Linking Risk Factors and DiseaseRisk FactorDiseaseAssociations not Cause & Effect

33. Strengths and Limitations of Epidemiological StudiesEspecially useful where high rates of rare diseases occur in small populationsProvide data on the actual incidence of diseaseDose-responses and exposure estimates are not neededLess effective in determining the causes of common diseases in large populationsDifficulties in correlating data across geographic areasCannot definitively prove cause and effectOften involve occupational exposures or case studies

34. CV = Comparison Value, i.e. RfDNOAEL = No Observed Adverse Effect LevelLOAEL = Lowest Observed Adverse Effect LevelExposure DoseDose-Response RelationshipsAssess the relevance of the critical studyReview other dose-response dataResponseDoseNOAELLOAELCVUncertainty Factor (3 – 1000 X)

35. Reference Dose (RfD)RfD = or UF = Uncertainty Factorex. interspeciesMF = Modifying Factorex. Completeness of overall dataThe daily exposure level which, during an entire lifetime of a human, appears to be without appreciable risk – mg/kg/day 

36. Estimated Exposure DoseEXP = Exposure DoseCwater = ConcentrationIR = Ingestion RateFI = Fraction of intake from sourceABSf = Bioavalability absorption factorEF = Exposure frequencyED = Exposure DurationBW = Body WeightAT = Averaging TimeEXP =  

37. MCLGRfD (mg/kg-day)Determined from toxicological or epidemiological dataThe Drinking Water Equivalent Level (DWEL) (mg/L) computed from the RfD assuming 2 L/day consumption and 70 kg body weightRSC is applied to DWEL to get MCLG MCLG = MCL = Maximum Contaminant LevelDWEL = Drinking Water Equivalent LevelRSC = Relative Source Contribution 

38. CarcinogensThe MCLG is traditionally set at zero for all carcinogensAssumed to be genotoxic (affects the cell’s genetic material)No thresholdNon-zero MCLGs are possible, reflecting non-genotoxic mode of action considerations

39. Cancer Risk AssessmentEPA applies a model to the available dataset to calculate the “cancer slope factor”Experimental exposures are highCancer happens after low-dose exposuresCancer Risk is calculated using exposure calculations and the cancer slope factorC = Concentration IR = Intake rateBW = Body weight Ef = Exposure frequencyED =Exposure durationAT =Averaging time SF = Cancer slope factor ADAF = Age-dependent adjustment factor 

40. Cancer RiskExample of cancer risk 2.4 X 10-05 This means that the risk calculation estimates that there will be 2.4 extra cases of cancer per 100,000 people over a lifetime of exposure.10-05 = 1/100,000

41. Health Advisories & Other Sources of Health Effects InformationRisk Assessment 101

42. EPA’s Health AdvisoriesServe as a technical guidance for federal, state, and local officialsHealth effectsAnalytical methodologiesTreatment technologiesTypesLifetime Health AdvisoryTen-day Health AdvisoryOne-day Health Advisory

43. Drinking Water Standards and Health AdvisoriesPrepared semi-annuallyContainHAsMCLGsMCLsOther informationhttp://water.epa.gov/action/advisories/drinking/upload/dwstandards2012.pdf

44. Other Sources of Health Effects InformationScientific LiteratureCCR – Consumer Confidence ReportsRequired by public water suppliers to be provided to customersSummarizes information regarding sources used, any detected contaminants, compliance, and educational informationIRIS – Integrated Risk In formation SystemMaintained by EPA: http://www.epa.gov/IRIS/ IRIS database is web accessible and contains human health information on more than 550 chemical substances

45. Other Sources of Health Effects InformationCDC – Centers for Disease Control and Prevention www.CDC.gov Maintains information on diseases, etiologies, and treatmentsMorbidity and Mortality Weekly Report www.cdc.gov/MMWR/ Surveillance Summaries for Waterborne Disease Outbreaks – US www.cdc.gov/healthywater/statistics/wbdoss/surveillance.html ATSDR – Agency for Toxic Substances and Disease RegistryToxicological profiles, www.atsdr.cdc.gov/toxprofiles/index.asp The World Health OrganizationGuidelines for Drinking Water Quality www.who.int/water_sanitation_health/dwq/gdwq3rev/en/

46. EPA SDWA Regulation Developmenthttp://water.epa.gov/lawsregs/rulesregs/regulatingcontaminants/index.cfm

47. Key TerminologyRisk Assessment 101

48. Key TerminologyNPDWR – National Primary Drinking Water RegulationLegally enforceable standardLimits levels of specific contaminants that can adversely affect public healthMaximum Contaminant Level or Treatment TechniqueNSDWR – National Secondary Drinking Water RegulationNon-enforceable guidelineCovers contaminants that may cause cosmetic or aesthetic effectsMCLG – Maximum Contaminant Level Goal§ 1412(b)(4)(A): “…level at which no known or anticipated adverse effects… occur and which allows for an adequate margin of safety”Not enforceableMCL – Maximum Contaminant Level§ 1412(b)(4)(B):“…level… which is as close to the maximum contaminant level goal as is feasible”Enforceable

49. Key TerminologyTT – Treatment Technique§ 1412(b)(7): “… in lieu of establishing a maximum contaminant level, if…it is not economically or technologically feasible to ascertain the level of the contaminant.”Enforceable MRDL – Maximum Residual Disinfectant LevelAnalogous to an MCLSets enforceable limits on residual disinfectants in the distribution systemMRDLG – Maximum Residual Disinfectant Level GoalAnalogous to an MCLG

50. Key TerminologyDose – A measure of intake of a substance, usually expressed in units of mg/kg-day (mg of contaminant per kg body weight per day)RfD – Reference Dose: The daily exposure level which, during an entire lifetime of a human, appears to be without appreciable riskRSC - Relative source contribution: The percentage of the RfD remaining after considering other exposure routesNOAEL – No Observed Adverse Effect Level: A dose based on experimental data that appears to result in no adverse effects.LOAEL – Lowest Observed Adverse Effect Level: The lowest dose used in a study that results in an observed adverse effect.

51. Contact InformationOffice Chief: Diane.Eckles@azdhs.gov Program Manager:Jennifer.Botsford@azdhs.govToxicologist:Linh@azdhs.gov Office Phone: (602) 364 - 3118