The Use of Technologies: Exposure (cross contamination), Risk Assessment, and Guidelines

Transcription

1 The Use of Technologies: Exposure (cross contamination), Risk Assessment, and Guidelines Nicholas J Ashbolt IoM Roundtable: Global Environmental Health Washington DC, October 17-18, 2007 Office of Research and Development National Exposure Research Laboratory, Cincinnati OH 45268

2 Technology use: Exposure Water fit-forpurpose Water & nutrients for recycling 1 World s first solar powered water supply system: AquaMeter deducts liters from the AquaCard, bought or recharged at the municipal hall (Butong), groundwater solar-pumped to feed tank & flows to outlets.*photos: WorldWaterPhilippines

3 Where we are today: reuse via irrigation Only Singapore, Malta, Israel & Namibia augment their source drinking water (10-20 %) with reclaimed wastewater Reverse Osmosis treatment of wastewaters (seawater) 2

4 An opportunity for change due to aging infrastructure 3 American Soc. Civil Eng Infrastructure Report Card D for drinking water new solutions are needed risk reversing public health gains D for wastewater sanitary sewer overflows release 10 billion gal raw sewage annually

5 Systems approach to evaluate multiple exposures & alternatives Irrigation Energy recovery Fertilizer 4 Ashbolt et al. (2006) In: 2nd IWA Leading-Edge on Sustainability in Water-Limited Environments. WEMS vol 10, IWA Publishing, London.

6 Microbiological issues associated with urban water systems 5 Piped systems leak Sewage (recreational & drinking water) Move towards dual distribution systems Cross-contamination Role of biofilms Move towards nutrient recovery Biosolids and urine

7 6 Risk Assessment

8 WHO Risk-management approach HEALTH TARGETS Acceptable risk Tolerable risk Risk Management (HACCP) Assess Environmental Exposure Assessment of risk (QMRA) PUBLIC HEALTH STATUS Fewtrell & Bartram (2001) In Water Quality: Guidelines, Standards and From: Fewtrell & Bartram, in Water Quality Guidelines, Standards and Health (WHO). IWA publishing. 7 Health (WHO) IWA Publishing

9 NRC Risk Framework (1983) Chemical or Microbial Risk Assessment Data Acquisition, Verification, Monitoring PROBLEM FORMULATION and SOURCE CHARACTERISATION Quantitation of dose & response Characterisation of Exposure Characterisation of Dose-Response RISK CHARACTERISATION Risk Communication 8 RISK MANAGEMENT

10 Quantitative Microbial Risk Assessment (QMRA) Provides information for managing safe water, e.g. via: Source water protection targets Treatment performance needs Effects of integrity losses Systems analysis approach 9

11 10 Example: target pathogens (not detectable in drinking water) Pathogen Max. tolerable concentration (per 100 L) Rotavirus 0.02 Hepatitis A virus Legionella pneumophila 0.09 Cryptosporidium parvum 1 Shiga Toxin E. coli O Based on WHO 1 DALY per million people per annum health target

12 11 Ramifications of the riskbased water Guidelines No longer focused on end-point testing for specific maximum contaminant criteria Also, water treated fit-for-purpose Which is based on the quality of the raw water (say wastewater) and the tolerable burden/dose of hazards (e.g. pathogens) at points of exposure Hence requires health-based targets for proactive system management What benchmark for safe water?

13 The WHO benchmark Disability adjusted life years (DALY) (since 1996) = years lived with illness + years of life lost (compared to average person for the region) 1 DALY per million people/y is considered acceptable, equal to about 1 case of cancer per 100,000 people over a lifetime of 70 years i.e. what the chemical industry has used for over 30 years 12 Murray & Lopez (1996) The Global Burden of Disease, Cambridge MA: Harvard School of Public Health on behalf of the World Health Organization and The World Bank

14 Information needed for QMRA: Chain model of infectious gastrointestinal disease No infection Symptom-less carrier Exposure Infection Acute, Self-limiting disease Complete recovery 13 Information for DALY Complications and chronic disease Residual symptoms Mortality

15 Population Morbidity Healthy AIDS* Mortality Healthy Example: DALY for 1000 cases of infection with Cryptosporidium Cases Duration (years) Severity weight Value YLD LYL AIDS* *prevalence assumed at 0.04% Health Burden YLD LYL DALY Healthy AIDS (years lived with disability) (life-years lost) Havelaar & Melse (2003) RIVM report , Bilthoven

16 Ozone disinfection versus bromate disinfection byproduct (DBP) Chlorination is ineffective against Cryptosporidium, but ozone is effective Yet it generates DBPs, particularly bromate Bromate induces tumors in rat kidney, thyroid & mesothelium, and renal cancers in mice WHO/EPA classify bromate as genotoxic carcinogen Lifetime cancer risk of 10-6 =0.3 µg/l 15 Havelaar et al. (2000) Environ. Health Persp. 108(4):

17 Mean estimates per 10 6 population O 3 benefit Cryptosporidium Bromate Total for effect Gastro gen pop Gastro AIDS Renal cancer Reduction Morbidity Mortality YLD YLL DALY Cryptosporidium 0.93 DALY/Mpy reduced to Havelaar et al. (2000) Environ. Health Persp. 108(4):

18 17 Guidelines

19 1 Max Contaminant 1 Max Level (MCL) Residual or Disinfectant Enforceable standard Level Treatment Tech (TT): E.g. EPA National Primary Drinking Water Standards 1 Nonenforceable goals 3 1/14/05 all systems treat 99% removal 18

20 Gov. Arnold Schwarzenegger Is strongly signaling that he does not support a chemical-by-chemical approach to regulating chemical risks in California despite making an exception in signing controversial California legislation phasing out some phthalates, a common class of plasticizer found in many children's products. 19 October 15, 2007 Inside Washington Publishers

21 HACCP approach used in WHO guidelines: For safe recreational waters (2003) Annapolis Protocol (1999) 3 rd Edition of the Drinking- Water Guidelines (2004) Water safety plans Wastewater reuse Vols 2 & 3 (2006) 20

22 System wide: Hazard Analysis & Critical Control Point (HACCP) management Watershed Outfall failure Filter breakthrough Waterfowl Human 21 Run-off Animal Reservoir Shortcircuiting Direct faecal (animal) input Treatment Turbidity challenge Distribution Integrity loss Biofilm pathogens Risk (infectivity) Exposure Volume consumed

23 MicroRisk EU project Applied source-to-customer QMRAs for ten drinking water systems Used six reference pathogens and examined hazardous events Greatest uncertainty in pathogen risks from distribution systems 22 Medema, G., Loret, J.-C., Stenström, T.A. & Ashbolt, N. (2006) Quantitative Microbial Risk Assessment in the Water Safety Plan.Final Report on the EU MicroRisk Project. Brussels: European Commission. Special Issue: Journal of Water and Health (2007) 5(Suppliment 1)

24 Pathogen to E. coli ratio 1 E+1 1 E+0 1 E-1 1 E-2 1 E-3 1 E-4 1 E-5 1 E-6 Estimated pathogen:e. coli ratios Individual ratios Mean (log. transformed) Mean + SD (log. transformed) Mean - SD (log. transformed) Arithmetic mean E-7 1 E Campy Crypto Giardia virus Campy Crypto Giardia virus virus all virus pos Sewage Surface water Groundwater van Lieverloo et al. (2007) J. Wat. Health 5(Suppl 1): virus cult

25 Outstanding issues: To reduce our uncertainties in estimating waterborne pathogen risks 24

26 Water management and uncertainty Statistical uncertainty Ignorance Technical Social Environmental 25 Scenario uncertainty

27 Major uncertainties in providing safe drinking water (Data gaps identified by undertaken QMRAs) Short-duration system failures (upstream & at treatment) that lead to fecal pathogens in drinking water How to detect and does residual chlorine provide health protection? 2. Distribution system intrusions (most common failure) are likely to overwhelm the chlorine residual again, how to detect?

28 And a more insidious problem 3. Opportunistic pathogens may grown in pipe biofilms, particularly in buildings (incl. non-potable) Not tested (Mycobacterium avium complex CCL-2) Possibly selected for by residual chlorine 27 Center for Biofilm Engineering

29 Drinking water outbreaks by agents USA (Liang et al., 2006 MMWR-SS 55[12]:31-65)

30 29 Opportunistic bacterial pathogens Various Legionella strains Mycobacterium avium, M. ulcerans Burkholderia pseudomallei Helicobacter pylori Campylobacter spp. Legionella within amoeba All grow associated with amoeba in biofilms & may be active but non-culturable

31 Pneumonia etiology 30 - identified in 40-60% of community-acquired pneumonia (Bochud et al Medicine 80(2):75-87 Falguera et al Arch Intern Med 161(15): ) are the others intracellular (amoeba) bacteria? Legionella pneumophila Chlamydophila pneumoniae Mycoplasma pneumoniae Coxiella burnetti Perhaps ~10-20% from these (Gilbert Greub, pers. comm.)

32 Emerging amoeba co-culturable (pneumonia) pathogens Strict intra-amoeba-growing pathogens: A) Acanthamoeba polyphaga Mimivirus, B) Parachlamydia acanthamoeba, C) Legionella dracoutii 31 (Raoult et al Clin. Inf. Dis. 45[1]:95-102)

33 Conclusions 32 For sustainable water options, need to consider: Fecal + non-fecal pathogens (i.e. do not just rely on E. coli) New ecological niches Source separation/reuse Various exposure routes Including hazardous events Institutions supportive to an integrative assessment approach

34 Acknowledgments & Disclaimer I would like to acknowledge the input of many international colleagues who have worked with me on aspects presented here This presentation does not necessarily reflect official U.S. EPA policy 33

35 Epidemic to endemic illnesses as detected by epidemiologic studies Outbreak detected Number of Cases Endemic rate Threshold for detection for an outbreak Undetected outbreak Sporadic Hyperendemic 34 Time (Frost et al., 1996 J.AWWA 88(9):66-75)

36 35 Disease burdens for different water contaminants