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Indicators for Waterborne Pathogens Appendix B Review of Previous Reports Like Appendix A, this appendix addresses a requirement of the committee’s statement of task; specifically the requirement to “review and provide perspective on the importance and public health impacts of waterborne pathogens as discussed in previous National Academies’ reports and other seminal reports.” NRC REPORTS Although this is the first National Research Council (NRC) study to focus specifically on indicators for waterborne pathogens, issues surrounding their use in a variety of applications have been discussed in several recent NRC reports, as summarized in Table B-1 beginning with the most recent. In addition, several of these reports include a discussion of the importance of waterborne pathogens to public health, which is reviewed in Chapters 1 and 2 of this report. OTHER SEMINAL REPORTS The U.S. Environmental Protection Agency (EPA) and other groups, including the water industry and academia, have addressed the issue of the microbial quality of drinking water and recreational water and its association with various human health effects such as gastroenteritis, ear and eye infections, dermatitis, and respiratory disease. Thus, Table B-1 also summarizes some of the major reports that have been published addressing these concerns. Many of the reports included in Table B-1 stress the need for better indicator approaches, including those designed to address the greatest public health threats.
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Indicators for Waterborne Pathogens For example, in light of the public health importance of viral pathogens in ground and coastal waters (as described in this report), several of the reports suggest that viral indicators, such as coliphage, be implemented. Other reports recommend development and use of molecular strategies so that new or (re)emerging pathogens can be detected in water. However, all reports included in Table B-1 agree that, given the documented public health impacts of waterborne disease, new and improved indicators of the presence of waterborne pathogens are needed. REFERENCES ASM (American Society for Microbiology). 1999. Microbial Pollutants in Our Nation’s Water—Environmental and Public Health Issues. Washington, D.C.: ASM Press. AWWARF (American Water Works Association Research Foundation). 2000a. An Epidemiological Study of Gastrointestinal Health Effects of Drinking Water. Denver, Colorado: American Water Works Association Research Foundation. AWWARF. 2000b. Development of a Decision Process for Prioritization of Emerging Pathogens Research. Denver, Colorado: American Water Works Association Research Foundation. AWWARF. 2001. Design of Early Warning and Predictive Source-Water Monitoring Systems. Denver, Colorado: American Water Works Association Research Foundation. EPA (U.S. Environmental Protection Agency). 1998. Improved Indicator Methods of Pathogen Occurrence in Water. Workshop Summary: August 10-11, 1998. Arlington, Virginia: Office of Water. EPA. 1999a. EPA Action Plan for Beaches and Recreational Waters. Washington, D.C.: Office of Research and Development and Office of Water. EPA-600-R-98-079. EPA. 1999b. Review of Potential Modeling Tools and Approaches to Support the BEACH Program. Washington, D.C.: Office of Science and Technology. EPA-823-R-99-002. EPA. 2001a. Developing Strategy for Waterborne Microbial Disease. Presentation at Waterborne Microbial Disease Stakeholder Meeting. November 6, 2001. Washington, D.C. EPA. 2001b. Protocol for Developing Pathogen TMDLs: First Edition. Washington, D.C.: Office of Water. EPA-841-R-00-002. EPA Workshop Group. 2001. Proceedings of Workshop on Development of Microbiological Criteria for Drinking Water Sources, Recreational Waters, and Shellfish Growing Waters, August 27-29. Washington, D.C.: Office of Water. ILSI (International Life Sciences Institute) Risk Science Institute. 1999. Early Warning Monitoring to Detect Hazardous Events in Water Supplies. T.K. Brosnan, ed. Washington, D.C.: International Life Sciences Institute. NRC (National Research Council). 1996. Use of Reclaimed Water and Sludge in Food Crop Production. Washington, D.C.: National Academy Press. NRC. 1998. Issues in Potable Reuse. Washington, D.C.: National Academy Press. NRC. 1999a. Setting Priorities for Drinking Water Contaminants. Washington, D.C.: National Academy Press. NRC. 1999b. Identifying Future Drinking Water Contaminants. Washington, D.C.: National Academy Press. NRC. 2000a. From Monsoons to Microbes. Washington, D.C.: National Academy Press. NRC. 2000b Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, D.C.: National Academy Press. NRC. 2001. Classifying Drinking Water Contaminants for Regulatory Consideration. Washington, D.C.: National Academy Press.
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Indicators for Waterborne Pathogens NRC. 2002a. Biosolids Applied to Land: Advancing Standards and Practices. Washington, D.C.: National Academy Press. NRC. 2002b. Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program. Washington, D.C.: National Academy Press.
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Indicators for Waterborne Pathogens TABLE B-1 Selected Studies and Reports that Address Waterborne Pathogens and Their Indicators Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge Biosolids Applied to Land (NRC, 2002a) To evaluate the technical approaches used (by EPA) to establish the chemical and pathogen standards for biosolids Recommendations: Further development and standardization of methods for measuring pathogens in biosolids are needed Research that uses improved pathogen detection technology should be promoted Research should be conducted to assess whether other indicator organisms, such as Clostridium perfringens, could be used in regulation of biosolids Opportunities to Improve the U.S. Geological Survey National Water Quality Assessment Program (NRC, 2002b) To provide guidance to the U.S. Geological Survey on opportunities to improve the National Water Quality Assessment (NAWQA) Program as it enters its second decade of nationwide monitoring Chapter 3 “NAWQA Cycle II Goals—Status”: Includes a brief review of the importance of waterborne pathogens in public health risk Conclusions: Monitoring of all microbes in water, coliforms and/or Escherichia coli is neither practical nor optimal, and a different assessment method is required Recommendations: Methods should be used to distinguish between live and dead viruses Coliphage assays should be performed at all groundwater wells (in NAWQA Program) Classifying Drinking Water Contaminants for Regulatory Consideration (NRC, 2001) To evaluate and revise conceptual approach to generate future Drinking Water Contaminant Candidate Lists (CCLs) first recommended in Identifying Future Drinking Water Contaminants (NRC, 1999b) Chapter 6 “Virulence-Factor Activity Relationships” (VFAR): Describes what VFARs are and concludes that the development and use of VFARs by EPA to help identify future waterborne pathogens appears to be feasible Recommendations: A scientific working group on bioinformatics, genomics, and proteomics should be established to inform EPA about, and eventually develop and implement, VFARs for drinking water contaminants
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Indicators for Waterborne Pathogens Development of Microbiological Criteria for Drinking Water Sources, Recreational Waters, and Shellfish Growing Waters (EPA Workshop, 2001) To identify approaches for the development of microbiological criteria for drinking water sources and other ambient water uses Conclusions and recommendations: Three approaches for the development of microbiological criteria were recommended: (1) selection of one or more pathogens or their surrogates to serve as an indicator of health risk; (2) selection of a single parameter that best correlates with the health risk, indicates the overall fecal or pathogen contamination concentrations in ambient waters, and helps identify the sources of contamination; and (3) development of an index composed of multiple parameters that will indicate waterborne pathogen concentrations and the health risk of gastrointestinal illness. The single indicator approach was considered the weakest A national research program can be implemented to develop criteria using any of the three approaches Development of the criteria should be considered an iterative process. A long-term commitment should be made to develop criteria that will identify both sources of microbial contamination and health risks Developing Strategy for Waterborne Microbial Disease (draft) (EPA, 2001a) To develop a strategy that unites the influence of the Safe Drinking Water Act and the Clean Water Act Conclusions: Research is needed in (1) development of technically sound criteria and risk assessment; (2) development of monitoring tools and diagnostic techniques to rapidly and accurately measure pathogens in different media and determine the potential causes and sources of contamination; and (3) development of modeling tools for forecasting impacts of controlling pathogens through alternative protection and restoration strategies
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Indicators for Waterborne Pathogens Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge Recommendation: Development of an integrated strategy to reduce the negative impact of microbiological contamination of U.S. waters. Water resource managers must be provided with a sound scientific basis so that they can protect and restore water bodies from microbial contamination via point and nonpoint source discharges by using cost-effective and readily applicable techniques Design of Early Warning and Predictive Source-Water Monitoring Systems (AWWARF, 2001) To provide water utilities with information to help them better assess the needs, options, design, and operation of early-warning and source water monitoring programs Conclusions: Source water contamination is a significant issue that should be addressed through improved early warning systems; sophisticated systems are the exception rather than the rule Even with advanced systems, the risk of contaminants in the source water getting into the water supplies exists Recommendations: A two-step risk-based process for making decisions related to early warning systems. Guidance for the design and operation of early warning systems was provided Protocol for Developing Pathogen TMDLs (First Edition) (EPA, 2001b) To assist the development of rational, science-based assessments and decisions that will lead to understandable and justifiable pathogen total maximum daily loads (TMDLs) Provides a step-by-step description of the TMDL process for pathogens and includes case studies and hypothetical examples to illustrate the major points in the process Recommendations: States, territories, and tribes should establish TMDLs that will meet water quality standards for each listed water, considering seasonal variations and a margin of safety that accounts for uncertainty
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Indicators for Waterborne Pathogens TMDL submittals should include a monitoring plan to determine whether the TMDL has resulted in attaining water quality standards and to support any revisions to the TMDL that might be required Potential indicator organisms for TMDL development include the following: Viruses: F1 coliphage; MS2 bacteriophage; poliovirus type 1 strain Lsc2ab; enteroviruses Coliform bacteria: total and fecal coliform; E. coli; Klebsiella spp. Enterococcal bacteria: Streptococcus faecalis; S. faecium Protozoa: Cryptosporidium spp.; Giardia spp. An Epidemiological Study of Gastrointestinal Health Effects of Drinking Water (AWWARF, 2000a) To evaluate drinking water-related gastrointestinal illnesses in a population consuming tap water of a quality that meets current water regulations; determine the source of these illnesses should health effects be observed; provide regulatory agencies and public health authorities with information on health risks associated with drinking water; and find suitable risk indicators Findings: There were more illnesses among tap water consumers than among subjects in the purified (bottled) water group, suggesting a potential adverse effect originating from the plant or the distribution system. Children were consistently more affected than adults Conclusion: Studies are needed to determine the source of these illnesses (i.e., source water quality, efficacy of treatment, distribution system integrity, and population immunity levels to various pathogens) Development of a Decision Process for Prioritization of Emerging Pathogens Research (AWWARF, 2000b) To develop a decision support tool to assist expert panels in the allocation of limited resources for research related to emerging waterborne pathogens Findings: A computerized Emerging Pathogens Decision Support System (EPDSS) was developed to evaluate and prioritize waterborne organisms of concern. EPDSS uses quantitative or semiquantitative processes of risk, uncertainty, and decision analysis
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Indicators for Waterborne Pathogens Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge Broad categories of information to be considered in evaluating a pathogen for future research funding should include public health significance; occurrence and ecology; effective or current water treatment; and adequacy of current analytical methods The structure of EPDSS has two levels of detail, with the second level nested inside the upper level to ensure consistency. Four sets of basic questions are addressed: (1) Are any health effects associated with exposure to this microbe (hazard identification)? (2) To what concentrations are people exposed through all routes considered (exposure assessment)? (3) What is the relationship between exposure to the microbe and probability, severity, or frequency of illness (exposure-response assessment)? (4) What is the overall risk to public health from this microbe? What is the variability of this risk? What is the uncertainty in risk estimates (risk characterization)? From Monsoons to Microbes (NRC, 2000a) Overview document based in part on a workshop to elucidate the ocean’s role in human health and suggest directions for future efforts to respond to health needs and threats Chapter 2 “Infectious Diseases” Lists: Major agents of waterborne disease conveyed by the coastal ocean and their usual routes of transmission to humans Problems associated with fecal coliforms, as well as E. coli and enterococci, as indicators include little association with disease-causing organisms, survival for long times in aquatic habitats, and so on Discussions: Problems associated with detection and prevention; for example, in seawater, many organisms remain in a viable but non-culturable state
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Indicators for Waterborne Pathogens Emerging indicator approaches, such as coliphage, gene probes, and immunoassays, were presented Watershed Management for Potable Water Supply: Assessing the New York City Strategy (NRC, 2000b) Evaluates the New York City Watershed Memorandum of Agreement (MoA), a comprehensive watershed management plan Chapter 5 “Sources of Pollution in the New York City Watershed” emphasizes the public health importance of protozoan parasites Cryptosporidium and Giardia and their that allows the City to avoid filtration of its current and future regulatory importance under the federal large upstate surface water supply Safe Drinking Water Act Chapter 6 “Tools for Monitoring and Evaluation” Recommends: Determine the lowest incidence of waterborne disease that can be detected by the City’s then current outbreak detection program and increase the sensitivity by studying specific populations A Cryptosporidium risk assessment be performed on a periodic basis for New York City An ongoing program of risk assessment should be used as a complement to active disease surveillance Appendix C “Microbial Risk Assessment Methods” emphasizes the potential usefulness of linking microbial risk assessment with an epidemiologic surveillance program. Setting Priorities for Drinking Water Contaminants (NRC, 1999a) First report to establish a process for setting priorities for an existing CCL; to establish framework for deciding what to regulate, monitor, or study further Chapter 3 “Review of Methods for Assessing Microbial Pathogens” Conclusions: There are deficiencies in fecal coliform use as an indicator; for example, it does not account for survival or transport of viral and protozoan pathogens, and pathogens originate from places other than human fecal material
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Indicators for Waterborne Pathogens Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge Limitations in data on health effects of emerging waterborne pathogens make it difficult to establish specific priorities for future regulation, and the expertise is also limited Identifying Future Drinking Water Contaminants (NRC, 1999b) Short committee report to identify emerging drinking water contaminants and develop a database to support future decision making on these, as well as help develop an approach to determine future CCLs Report includes three individually authored chapters on (1) historical overview of drinking water contaminants and public water utilities, (2) emerging pathogens, and (3) methods to identify and detect microbial contaminants in drinking water Emphasizes the inclusion of microbes and all other types of potential contaminants on preliminary and final CCLs Recommendations: Use common mechanisms of pathogenicity among contaminants in order to include them on future CCLs (analogous to using chemical structure-activity relationships [SARs] for CCLs) Early Warning Monitoring to Detect Hazardous Events in Water−Supplies (ILSI Workshop, 1999) To define the state of the science for early-warning monitoring systems for drinking water; to identify strengths and weaknesses of existing technologies and strategies; to raise consciousness regarding the potential for the occurrence of transient hazardous events; and to promote research into prevention, detection, and mitigation or treatment of these events Conclusions and recommendations: The detection of hazardous events in source water, especially rivers, is a primary concern Conventional indicators of water quality are of little value in situations of intentional acts such as the introduction of microbial pathogens or biotoxins into a water system; new and more accurate methods are needed to detect intentional and unintentional microbial hazards introduced into the system Ideal microbial monitoring methods should be rapid, providing results in 2 hours or less
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Indicators for Waterborne Pathogens Several new approaches were identified, including several optical and assay technologies, but most are still in the research and development phase. Monitoring of health effects in the community using enhanced surveillance strategies to provide early detection of epidemics should be considered because no monitoring system can be constructed to detect all threats Microbial Pollutants in our Nation’s Water—Environmental and Public Health Issues (ASM, 1999) To focus attention on the risk of microbial pollutants in water Conclusions and recommendations: Current evidence indicates that microbial pollutants in water, when compared to chemicals, pose far greater risks to communities EPA needs to focus more on microorganisms in its initiative to study the nation’s watersheds. Current indicators of watershed health do not include microbial contaminants of public health concern. The Clean Water Act has to be changed to include more emphasis on microbial threats. Coliform bacteria are not useful for assessing risks due to viruses and protozoa A task force comprised of EPA, the Centers for Disease Control and Prevention (CDC), the National Institute for Environmental Health Sciences, and other federal agencies, as well as universities and other nongovernmental groups, should be established to outline a national initiative with the goal of protecting the public from waterborne pathogens An independent scientific assessment should be initiated to address the microbial safety of the nation’s water Action Plan for Beaches and Recreational Waters (BEACH Program) (EPA, 1999a) To reduce the risk of infection to users of recreational waters through improvements in recreational water programs, communication, and scientific advances; to describe EPA actions to improve and assist state, tribal, and Recommendations: EPA should sponsor conferences and meetings with federal, state, tribal, and local representatives to identify the needs’s and deficiencies of recreational water quality monitoring programs
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Indicators for Waterborne Pathogens Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge local implementation of recreational water monitoring and public notification programs EPA should strengthen water quality standards and implementation programs by developing policies and assisting local managers in their transition to recommend criteria (i.e., E. coli and enterococci indicators rather than total and fecal coliforms) EPA should conduct national Beach Health Surveys annually to collect detailed data on state and local monitoring efforts, applicable standards, water quality communications methods, the nature and extent of contamination problems, and any protection activities A risk-based evaluation and classification process should be developed, and beaches should be ranked as high, medium, and low Three broad areas of scientific research should be addressed to improve the science that supports recreational water monitoring programs: (1) water quality indicators research; (2) modeling and monitoring research; and (3) exposure and health effects research Review of Potential Modeling Tools and Approaches to Support the BEACH Program (EPA, 1999b) To provide an inventory of predictive models or tools currently in use by agencies responsible for evaluating the need for closing beaches or issuing advisories and warnings Conclusions: Waterborne pathogens contaminating recreational areas can originate from various sources located either within the proximity of the beach or at upstream locations within the drainage area or watershed Beach advisories or closures are issued when pathogen concentrations exceed the water quality standard or local action level; several agencies use mathematical models to predict increased pathogen concentrations
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Indicators for Waterborne Pathogens Selection of the appropriate model for beach advisories will depend on the site conditions of the waterbody of concern. The report reviews the selection of the appropriate model based on a list of screening factors Water quality predictive tools that could be applied to beach advisories but are not currently in use by local agencies include pathogen loadings from point- and nonpoint sources and pathogen fate and transport Improved Indicator Methods of Pathogen Occurrence in Water (EPA Workshop, 1998) To provide scientific and technical guidance on current and alternative indicators and methods; to suggest ways for indicator technology to improve health protection; and to discuss approaches for future dialogues to further the process Conclusions and recommendations: E. coli should replace total coliforms as an indicator for recreational, raw, surface, and agricultural waters E. coli should be used not as a single indicator to be applied universally but as an indicator that covers a large part of the field A combination of biological and nonbiological measurements (e.g., fecals, turbidity, customer complaints) for intrusion should be used EPA should use E. coli as the premier indicator for health threats and should reduce the percentages in regulations because regrowth occurs Information on the number of fecal coliform violations in the United States that involved E. coli should be collected E. coli data should be added to existing data on coliforms so that historical information and databases do not have to be discarded Issues in Potable Reuse (NRC, 1998) To assess public health implications of using reclaimed water as a component of the potable water supply Chapter 3 “Microbial Contaminants in Reuse Systems” Recommendations: Facilities should report on effectiveness of treatment processes in removing microbial pathogens
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Indicators for Waterborne Pathogens Title Focus of Study Points of Emphasis Related to Indicators for Waterborne Pathogens and Committee’s Charge EPA should support research and development on methods for detecting emerging pathogens in environmental samples Both industry and the research community should develop performance goals appropriate for planned potable reuse Use of Reclaimed Water and Sludge in Food Crop Production (NRC, 1996) To examine the use of treated municipal wastewater and sludge in the production of crops for human consumption Chapter 5 “Public Health Concerns about Infectious Disease Agents” outlines leading pathogens associated with raw sewage and emphasizes the need to be able to effectively monitor for treatment efficacy and, therefore, the need for effective indicator organisms or direct pathogen detection Conclusions: Coliforms are not reliable for direct pathogen detection; Clostridium perfringens should be used instead There is potential in emerging immunological and molecular biological methods
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