Risky? A new WERF study of Pathogen Discharges Candice Owen, PE, LEED AP, CFM

Transcription

1 Risky? A new WERF study of Pathogen Discharges Candice Owen, PE, LEED AP, CFM

2 Outline Current Status of REC Criteria Quantitative Microbial Risk Assessment WERF QMRA Study 2

3 REC Criteria

4 REC Uses 4

5 REC Criteria Large number of water bodies in the U.S. are currently categorized as unsafe for recreation Bacteria is #1 cause of impairment in USA Over 6,000 Bacteria TMDLs completed (>10,000 remaining) However: Some of these water bodies are relatively unaffected by human activities or subject to zero recreational use Clean-up challenges can be daunting Indicators have shortcomings 5

6 REC Criteria How does EPA currently determine which REC waters are unsafe? Fecal Indicator Bacteria (E.coli and Enterococcus) concentrations acceptable risks assumed from Epidemiological Studies Relationship between water contact and health outcomes New criteria must be developed by

7 USEPA s REC Criteria (1986) 7

8 USEPA s REC Criteria (1986) 8

9 USEPA s REC Criteria (1986) Acceptable Risk = 8/1000 Criteria = 126 MPN/100mL 9

10 REC Criteria Concerns with Current Criteria While Epidemiological Studies are powerful tools to manage REC health risks, issues with them include: Costly and Time Consuming Cannot be expected to representative for all water bodies in all areas of the country. Fecal Indicator Bacteria (FIB) (E. coli and Enterococcus) Quantification is simpler and less costly Testing takes up to 36 hours and is not conducive to real-time decisions Growing Evidence that FIB measured in REC waters is uncoupled with pathogenic discharges 10

11 REC Criteria Concerns with Current Criteria While Epidemiological Studies are powerful tools to manage REC health risks, issues with them include: Costly and Time Consuming Not always sufficient REC contact for robust study Cannot be expected to representative for all water bodies in all areas of the country. Fecal Indicator Bacteria (E. coli and Enterococcus) Quantification is simpler and less costly Testing takes up to 24 hours and is not conducive to real-time decisions Growing Evidence that FIB measured in REC waters is uncoupled with pathogenic discharges Why Not Measure Pathogens???? 11

12 Quantitative Microbial Risk Assessment (QMRA)

13 QMRA QMRA Quantitative Microbial Risk Assessment Mutli-step approach that couples Risk Assessment Principles with statistical computations to estimate consequences of possible exposure to infectious organisms Watershed Specific Data is input Monte Carlo statistical modeling approach to account for variability 13

14 QMRA RISK = Exposure x Potency Pathogen Concentrations (Measure) Ingestion Rate (Estimate) Duration (Assume) Dose-Response (Clinical Trials) 14

15 QMRA Flow Chart Step 1 Context Step 3 Exposure Step 2 Hazards Step 5 RISK SPIN! Step 4 Health Effects Step 6 Policy 15

16 QMRA What is QMRA s Role within REC Water Quality Criteria? Provide flexibility for implementation of REC Criteria Could be a Tiered Approach Use in cases where default epidemiological-study based criteria considered unrepresentative of watershed or hydrologic conditions 16

17 WERF QMRA Study

18 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 18

19 WERF Study International QMRA and risk assessment community Facilities and agencies monitoring water quality worldwide UC Davis S. Wuertz, W. Miller, P. Conrad, B. Byrne NIWA G. McBride, R. Stott Project Team AMEC Dustin Bambic Candice Owen 19

20 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 20

21 WERF Goals Demonstrate how current pathogen monitoring technologies can inform QMRA and modeling tools Support USEPA Critical Path Science Plan and development and of revised REC criteria END PRODUCT Tools to help managers estimate risks and prioritize watershed programs 21

22 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 22

23 WERF Study Study Design Quantification of Waterborne Pathogen Levels in Discharges-of- Concern: Collection of large volume samples Analysis of new comprehensive suite of bacteria, protozoa and viruses Evaluation of Methods to Determine Primary Fecal Sources Impacting Waterbodies Evaluation of Source Tracking Tools Ability to quantify human specific sources Estimation of Health Risks with QMRA: QMRA for high-priority pathogens Determining Risk for measured discharges-of-concern Consideration of QMRA s role in new REC Criteria 23

24 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 24

25 The WERF Toolkit BACTERIA: E. coli Enterococcus Salmonella Bacteroidales Bird-specific assay V. cholerae Campylobacter V. parahaemolyticus PROTOZOA: Giardia Cryptosporidium Toxoplasma VIRUSES: Adenovirus Enterovirus Norovirus Rotavirus Culture, Microscopy and Genetic Methods 25

26 The WERF Toolkit BACTERIA: E. coli Enterococcus Salmonella Bacteroidales Bird-specific assay V. cholerae Campylobacter V. parahaemolyticus PROTOZOA: Giardia Cryptosporidium Toxoplasma VIRUSES: Adenovirus Enterovirus Norovirus Rotavirus BOLD = Priority Pathogens 26

27 Sampling Regions 27

28 Sampling Sites Discharges-of-Concern 18 Total Sites Dry Season Urban Runoff Agricultural Stormwater Commercial/Light Industrial Stormwater Residential CSO Forested Open Space Mixed Use Stormwater 28

29 Total of 67 samples of this volume! 29

30 Filtering Samples 30

31 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 31

32 WERF Study Results Study Design Quantification of Waterborne Pathogen Levels in Discharges-of- Concern: Summary Statistics Cumulative Distribution Frequency Correlations Evaluation of Methods to Determine Primary Fecal Sources Impacting Waterbodies Successful use of model to quantify human sources Estimation of Health Risks with QMRA: Results for all types of discharges-of-concern for Adult Primary Use Adult Secondary Use Child Primary Use 32

33 Quantitative Microbial Source Tracking Results Probabilistic model Allows for correction of Bacteroidales results measured using quantitative Polymerase Chain Reaction analysis (qpcr) Uses equations given by Law of Total Probability Estimate true concentrations of individual fecal host contributors compared to the universal marker Help guide the interpretation of environmental monitoring studies 33

34 QMRA Results 34

35 QMRA Results 35

36 WERF Study Team Goals Study Design Discharge Sampling Results Conclusions 36

37 WERF Study Conclusions Useful to monitor in stormwater and natural runoff? Norovirus Rotavirus adenovirus 40/41 Most Prevalent and likely to cause illness? #1Norovirus is the most dominant health risk. #2 Rotavirus Mixing and inactivation did not necessarily reduce risk Can we determine amount of human sources? New model predict true amount of human fecal contamination 37

38 Conclusions Current criteria are based on a handful of epi studies, and indicators have shortcomings New REC criteria in 2012 QMRA may provide a powerful tool for protection of sites with unique conditions and sources WERF QMRA project has provided critical data and momentum to facilitate acceptance of QMRA Don t swallow viruses while swimming 38

39 QUESTIONS? Candice Owen AMEC Environment & Infrastructure Nashville, TN

40 QMRA Steps to Monte Carlo Simulation 40

41 Implementation of QMRA for CWA?? Other exceptional conditions that suggest epidemiological studies are not applicable? 41

42 E.coli Concentrations by IDEXX E.coli Concentration by IDEXX (MPN/100mL) of these graphs! Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (0% Non-Detect) Commercial/Light Industrial (0% Non-Detect) CSO (0% Non-Detect) Dry Season Urban Runoff (0% Non-Detect) Forested Open Space (0% Non-Detect) Residential (0% Non-Detect) Mixed Use (0% Non-Detect) 42

43 10 5 Cow Bacteroidales Concentrations by PMA-qPCR Cow Bacteroidales Concentration by PMA-qPCR (gc/ml) Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (75% Non-Detect) Commercial/Light Industrial (100% Non-Detect) CSO (100% Non-Detect) Dry Season Urban Runoff (100% Non-Detect) Forested Open Space (100% Non-Detect) Residential (100% Non-Detect) Mixed Use (100% Non-Detect) 43

44 10 4 Salmonella Concentrations by Culture Salmonella Concentration by Microscopy (MPN/10L) Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (63% Non-Detect) Commercial/Light Industrial (69% Non-Detect) CSO (67% Non-Detect) Dry Season Urban Runoff (88% Non-Detect) Forested Open Space (57% Non-Detect) Residential (79% Non-Detect) Mixed Use (0% Non-Detect) Open symbols denote samples with qualifiers 44

45 10 4 Cryptosporidium Concentrations by Microscopy Cryptosporidium Concentration by Microscopy (oocysts/10l) Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (38% Non-Detect) Commercial/Light Industrial (77% Non-Detect) CSO (67% Non-Detect) Dry Season Urban Runoff (100% Non-Detect) Forested Open Space (0% Non-Detect) Residential (50% Non-Detect) Mixed Use (50% Non-Detect) 45

46 10 6 Rotavirus Concentrations by qpcr Rotavirus Concentration by qpcr (gc/ml) Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (38% Non-Detect) Commercial/Light Industrial (69% Non-Detect) CSO (100% Non-Detect) Dry Season Urban Runoff (88% Non-Detect) Forested Open Space (71% Non-Detect) Residential (44% Non-Detect) Mixed Use (83% Non-Detect) 46

47 10 5 Norovirus GI Concentrations by qpcr Norovirus GI Concentration by qpcr (gc/ml) Percentage of Concentrations Less than or Equal to Measured Value (%) Agriculture (63% Non-Detect) Commercial/Light Industrial (46% Non-Detect) CSO (67% Non-Detect) Dry Season Urban Runoff (88% Non-Detect) Forested Open Space (43% Non-Detect) Residential (25% Non-Detect) Mixed Use (25% Non-Detect) 47

48 Sources of Bacteria

49 Bacteria Sources Usual suspects: Leaking sanitary sewer lines Poorly maintained septic systems Renegade RVs Homeless persons Household pets Livestock Wildlife Regrowth/Resuspension,etc. 49

50 Usual suspects: Leaking sanitary sewer lines Poorly maintained septic systems Renegade RVs Homeless persons Household pets Livestock Wildlife Regrowth/Resuspension,etc. Bacteria Sources HUMAN 50

51 Bacteria Sources Usual suspects: Leaking sanitary sewer lines Poorly maintained septic systems Renegade RVs Homeless persons Household pets Livestock Wildlife Regrowth/Resuspension,etc. Non-HUMAN, Controllable 51

52 Bacteria Sources Usual suspects: Leaking sanitary sewer lines Poorly maintained septic systems Renegade RVs Homeless persons Household pets Livestock Wildlife Regrowth/Resuspension,etc. Non-HUMAN, Uncontrollable (?) 52

53 Bacteria Sources Usual suspects: Leaking sanitary sewer lines Poorly maintained septic systems Renegade RVs Homeless persons Household pets Livestock Wildlife Regrowth/Resuspension,etc. Ubiquity, Persistence (?) 53

54 Persistence

55 Sediments as a Source of Bacteria Byappanahalli, M., Fowler, M., Shively, D. and Whitman, R. (2003). Ubiquity and Persistence of Escherichia coli in a Midwestern Coastal Stream. Applied and Environmental Microbiology 69(8):

56 Growth

57 Growth in Urban Runoff Jiang et al., Microbial source tracking in a small southern California urban Watershed indicates wild animals and growth as the source of bacteria. Appl. Microbiol. Biotechnol. (2007) 76:

58 Exposure (Example) Number of adenovirus 4 infections per 1000 exposures o sewage (uncertainty): 88%; 20, 2, 1 2o sewage (certainty): 88%; 20, 2, 1 Stormwater (uncertainty): 10%; 20, 2, 1 Stormwater (certainty): 10%; 20, 2, Time percentile 58