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Health and Wellness for all Arizonans azdhs.gov Advisory Panel on Emerging Contaminants (APEC) Risk Assessment 101 Jennifer Botsford, MSPH ADHS Office.

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Presentation on theme: "Health and Wellness for all Arizonans azdhs.gov Advisory Panel on Emerging Contaminants (APEC) Risk Assessment 101 Jennifer Botsford, MSPH ADHS Office."— Presentation transcript:

1 Health and Wellness for all Arizonans azdhs.gov Advisory Panel on Emerging Contaminants (APEC) Risk Assessment 101 Jennifer Botsford, MSPH ADHS Office of Environmental Health February 15, 2013

2 Health and Wellness for all Arizonans azdhs.gov Overview Introduction Key Terminology Developing NPDWRs MCLs and TTs Health Hazards Setting MCLGs Health Advisories and Other Sources of Health Effects Information

3 Health and Wellness for all Arizonans azdhs.gov INTRODUCTION Risk Assessment 101

4 Health and Wellness for all Arizonans azdhs.gov Introduction Risk 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 options Maximum Contaminant Levels (MCLs) Treatment Technique (TT)

5 Health and Wellness for all Arizonans azdhs.gov What is Risk?

6 Health and Wellness for all Arizonans azdhs.gov What is Risk?

7 Health and Wellness for all Arizonans azdhs.gov What is Safe? Free from harm or risk Secure from threat of danger, harm, or loss Zero risk Adapted from:

8 Health and Wellness for all Arizonans azdhs.gov What is Risk? Possibility of loss or injury, peril The chance of loss; the degree of probability of such loss Adapted from:

9 Health and Wellness for all Arizonans azdhs.gov Introduction What is risk? – The probability of injury, disease, or death from exposure to a chemical agent or a mixture of chemicals – EPA definition from IRIS (Integrated Risk Information System)

10 Health and Wellness for all Arizonans azdhs.gov DEVELOPING NPDWRS (NATIONAL PRIMARY DRINKING WATER REGULATIONS) Risk Assessment 101

11 Health and Wellness for all Arizonans azdhs.gov National Primary Drinking Water Regulations (NPDWRs) Microorganisms – 7 standards addressing microorganisms 3 bacteria, viruses, 4 indicators (i.e. turbidity) Disinfection Byproducts – 4 standards Disinfectants – 3 standards Inorganic Chemicals – 16 standards Organic Chemicals – 53 standards Radionuclides – 4 standards Currently there are 87 legally enforceable standards

12 Health and Wellness for all Arizonans azdhs.gov Key Steps for Developing NPDWRs Setting the MCLG – Health effects information – Exposure information – Relevant information and procedures developed by EPA for risk assessment and characterization Assess whether an MCL or TT is more appropriate Identify and evaluate costs and effectiveness of treatment alternatives Specify Best Available Technology (BAT)

13 Health and Wellness for all Arizonans azdhs.gov Key Steps for Developing NPDWRs Evaluate contaminant occurrence – Number or systems affected – To what degree are they affected Evaluate contaminant exposure – Number of people affected – To what degree are they affected Characterize compliance choices for regulatory alternatives

14 Health and Wellness for all Arizonans azdhs.gov Key Steps for Developing NPDWRs Develop multiple MCL (or TT) alternatives – Compare benefits and costs; address uncertainty – Document the underlying data and analyses to support the proposed or final rule Economic Analysis Health Criteria Document Occurrence and Exposure Document Cost and Technology Document

15 Health and Wellness for all Arizonans azdhs.gov MCLS AND TTS Risk Assessment 101

16 Health and Wellness for all Arizonans azdhs.gov Maximum Contaminant Level Is enforceable Set as close to the MCLG as feasible Feasible is the level that may be achieved: Best available technology (BAT), treatment technique Examination for efficiency under field conditions and not solely under laboratory conditions Taking cost into consideration Requires a determination as to whether the benefits justify the costs

17 Health and Wellness for all Arizonans azdhs.gov Treatment Technique Alternative to an MCL when it is not economically and technologically feasible to ascertain the level of the contaminant – Common for microbiological contaminants A TT is also an enforceable standard involving a measurable procedure or level of technological performance (e.g. Action Level) – Surface Water Treatment Rule – Lead and Copper Rule

18 Health and Wellness for all Arizonans azdhs.gov HEALTH HAZARDS Risk Assessment 101

19 Health and Wellness for all Arizonans azdhs.gov Health Effects Evaluation Components of Risk Assessment in Rulemaking Hazard Identification Risk Characterization Exposure Assessment Dose-Response Assessment Risk Management: Regulatory Alternatives Development

20 Health and Wellness for all Arizonans azdhs.gov Types of Contaminants Microbiological – Waterborne pathogens Biological toxins Chemicals – Naturally occurring – Man-made – Used in commerce, pesticides Disinfection products and byproducts

21 Health and Wellness for all Arizonans azdhs.gov Identifying Adverse Health Effects Magnitude Frequency Route Duration of exposure Two broad categories of health effects: – Cancer – Non-cancer

22 Health and Wellness for all Arizonans azdhs.gov Exposure Assessment Acute Exposure – Short term exposure Chronic Exposure – Long term exposure Critical Periods – Period when an organ/system is most vulnerable Route of exposure – inhalation, ingestion, dermal Carcinogenicity Categories – Carcinogenic to Humans – Likely to be Carcinogenic to Humans – Suggestive Evidence of Carcinogenic Potential – Inadequate Information to Assess Carcinogenic Potential – Not Likely to be Carcinogenic to Humans

23 Health and Wellness for all Arizonans azdhs.gov Sensitive Populations Infants and children – Pound for pound, drink more, eat more, breathe more than adults – Developing (i.e. lead) – Immature organs may not be able to metabolize/ neutralize contaminants – Habits (i.e. putting objects in mouth, pica) Pregnant women & fetuses – Developing organs – Critical period

24 Health and Wellness for all Arizonans azdhs.gov Sensitive Populations Elderly people – Biological changes associated with aging – Ex. blood flow metabolic rates kidney function ability to eliminate substances from body Immunocompromised individuals – Weakened immune system Drugs, cancer, transplant patients, HIV/AIDS – Particularly sensitive to pathogens, may experience longer or more severe symptoms Highly exposed individuals – Higher intake rates (i.e. athlete drinking more water than the average person) – Occupational exposures

25 Health and Wellness for all Arizonans azdhs.gov Health Effects Evaluation Gastrointestinal Neurological Hepatic Cardiovascular & Hematological Reproductive & Developmental Respiratory Dermatological Renal

26 Health and Wellness for all Arizonans azdhs.gov SETTING MCLGS Risk Assessment 101

27 Health and Wellness for all Arizonans azdhs.gov MCLGs: Maximum Contaminant Level Goals Maximum 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-cancer – Acute or chronic exposure concerns – Sensitive populations Data obtained from epidemiological and toxicological studies

28 Health and Wellness for all Arizonans azdhs.gov Toxicological Studies Toxicology – the study of poisons and their actions Toxicological experiments often – Involve non-human experiments – Involve small numbers of animals – High exposure doses – Use mathematical models to determine the concentration of the chemical that would cause disease in people EPA uses the studies with the greatest margin of safety (overestimation of risk)

29 Health and Wellness for all Arizonans azdhs.gov Toxicological Study Methods Some animals subjected to high doses of chemicals – Necessary to observe statistically significant rates of disease Other animals exposed to lower doses of chemicals – Necessary to provide data inputs for a dose-response curve Long-term carcinogenicity studies Use these studies together to develop a dose-response curve

30 Health and Wellness for all Arizonans azdhs.gov Strengths and Limitations of Toxicology Studies Environmental Factors, i.e. exposure to contaminants can be controlled – Contaminant under study – Other exposures Facilitates interpretation of results Uncertainty associated with extrapolating – From high doses tested to environmentally relevant doses – From effects on animals to effects on humans

31 Health and Wellness for all Arizonans azdhs.gov Epidemiological Studies Epidemiology – the study of how, when, and where diseases occur in populations of humans, and the application of study results to control a public health problem Studies based on human exposure Epidemiologists seek to identify: – Risk factors associated with the occurrence of disease – Protective factors that reduce the risk of disease

32 Health and Wellness for all Arizonans azdhs.gov Linking Risk Factors and Disease Risk Factor Disease Associations not Cause & Effect

33 Health and Wellness for all Arizonans azdhs.gov Strengths and Limitations of Epidemiological Studies Especially useful where high rates of rare diseases occur in small populations Provide data on the actual incidence of disease Dose-responses and exposure estimates are not needed Less effective in determining the causes of common diseases in large populations Difficulties in correlating data across geographic areas Cannot definitively prove cause and effect Often involve occupational exposures or case studies

34 Health and Wellness for all Arizonans azdhs.gov CV = Comparison Value, i.e. RfD NOAEL = No Observed Adverse Effect Level LOAEL = Lowest Observed Adverse Effect Level Exposure Dose Dose-Response Relationships Assess the relevance of the critical study Review other dose- response data Response Dose NOAELLOAEL CV Uncertainty Factor (3 – 1000 X) Uncertainty Factor (3 – 1000 X)

35 Health and Wellness for all Arizonans azdhs.gov Reference Dose (RfD)

36 Health and Wellness for all Arizonans azdhs.gov Estimated Exposure Dose EXP = Exposure Dose C water = Concentration IR = Ingestion Rate FI = Fraction of intake from source ABS f = Bioavalability absorption factor EF = Exposure frequency ED = Exposure Duration BW = Body Weight AT = Averaging Time

37 Health and Wellness for all Arizonans azdhs.gov MCLG RfD (mg/kg-day) – Determined from toxicological or epidemiological data The Drinking Water Equivalent Level (DWEL) (mg/L) – computed from the RfD assuming 2 L/day consumption and 70 kg body weight RSC is applied to DWEL to get MCLG

38 Health and Wellness for all Arizonans azdhs.gov Carcinogens The MCLG is traditionally set at zero for all carcinogens – Assumed to be genotoxic (affects the cells genetic material) – No threshold Non-zero MCLGs are possible, reflecting non- genotoxic mode of action considerations

39 Health and Wellness for all Arizonans azdhs.gov Cancer Risk Assessment EPA applies a model to the available dataset to calculate the cancer slope factor – Experimental exposures are high – Cancer happens after low-dose exposures Cancer Risk is calculated using exposure calculations and the cancer slope factor C = Concentration IR = Intake rate BW = Body weight Ef = Exposure frequency ED =Exposure duration AT =Averaging time SF = Cancer slope factor ADAF = Age-dependent adjustment factor

40 Health and Wellness for all Arizonans azdhs.gov Cancer Risk Example of cancer risk – 2.4 X – 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 = 1/100,000

41 Health and Wellness for all Arizonans azdhs.gov HEALTH ADVISORIES & OTHER SOURCES OF HEALTH EFFECTS INFORMATION Risk Assessment 101

42 Health and Wellness for all Arizonans azdhs.gov EPAs Health Advisories Serve as a technical guidance for federal, state, and local officials – Health effects – Analytical methodologies – Treatment technologies Types – Lifetime Health Advisory – Ten-day Health Advisory – One-day Health Advisory

43 Health and Wellness for all Arizonans azdhs.gov Drinking Water Standards and Health Advisories Prepared semi-annually Contain – HAs – MCLGs – MCLs – Other information

44 Health and Wellness for all Arizonans azdhs.gov Other Sources of Health Effects Information Scientific Literature CCR – Consumer Confidence Reports – Required by public water suppliers to be provided to customers – Summarizes information regarding sources used, any detected contaminants, compliance, and educational information IRIS – Integrated Risk In formation System – Maintained by EPA: – IRIS database is web accessible and contains human health information on more than 550 chemical substances

45 Health and Wellness for all Arizonans azdhs.gov Other Sources of Health Effects Information CDC – Centers for Disease Control and Prevention – Maintains information on diseases, etiologies, and treatments – Morbidity and Mortality Weekly Report – Surveillance Summaries for Waterborne Disease Outbreaks – US ATSDR – Agency for Toxic Substances and Disease Registry – Toxicological profiles, The World Health Organization – Guidelines for Drinking Water Quality

46 Health and Wellness for all Arizonans azdhs.gov EPA SDWA Regulation Development atingcontaminants/index.cfm atingcontaminants/index.cfm

47 Health and Wellness for all Arizonans azdhs.gov KEY TERMINOLOGY Risk Assessment 101

48 Health and Wellness for all Arizonans azdhs.gov Key Terminology NPDWR – National Primary Drinking Water Regulation – Legally enforceable standard – Limits levels of specific contaminants that can adversely affect public health – Maximum Contaminant Level or Treatment Technique NSDWR – National Secondary Drinking Water Regulation – Non-enforceable guideline – Covers contaminants that may cause cosmetic or aesthetic effects MCLG – 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 enforceable MCL – Maximum Contaminant Level – § 1412(b)(4)(B):…level… which is as close to the maximum contaminant level goal as is feasible – Enforceable

49 Health and Wellness for all Arizonans azdhs.gov Key Terminology TT – 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 Level – Analogous to an MCL – Sets enforceable limits on residual disinfectants in the distribution system MRDLG – Maximum Residual Disinfectant Level Goal – Analogous to an MCLG

50 Health and Wellness for all Arizonans azdhs.gov Key Terminology Dose – 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 risk RSC - Relative source contribution: The percentage of the RfD remaining after considering other exposure routes NOAEL – 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 Health and Wellness for all Arizonans azdhs.gov Contact Information Office Chief: – Program Manager: – Toxicologist: – Office Phone: (602)


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