Indicators for Waterborne Pathogens (2004) / Chapter Skim
Currently Skimming:
Executive Summary
Executive Summary
Pages 1-16
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
, it is important to have accurate, reliable, and scientifically defensible methods for determining whether source waters for drinking water and recreational waters are contaminated by pathogens and to what extent. For more than 100 years, U.S.
|
From page 2... ...
Nonetheless, indicator approaches will still be required for the foreseeable future because it is not practical or feasible to monitor for the complete spectrum of microorganisms that may occur in source waters for drinking water and recreational waters, and many known pathogens are difficult to detect directly and reliably in water samples. This report was written by the National Research Council (NRC)
|
From page 3... ...
In doing so, the com mittee will: · define currently known waterborne pathogen classes and an ticipate those emerging waterborne pathogens that are likely to be of public health concern; · evaluate the strengths and weaknesses of the candidates for reflecting the presence, quantity, and viability of these important patho gens; · explore whether a selected subset of indicators, a unique indi cator, and/or specific indicator approaches can help to identify the source or sources of water contamination (including discharges from municipal publicly owned treatment works) ; · assess the practicality of using these candidates at local, state, and federal levels given current technology, personnel, and water quality monitoring programs; · comment on data, research, and information needs for short and long-term validation of candidates; and · consider how the list of recommended candidates might change with future technological developments.
|
From page 4... ...
HEALTH EFFECTS ASSESSMENT: EPIDEMIOLOGY OF WATERBORNE HUMAN DISEASE The ultimate objective for determining the microbiological quality of water is to identify and then minimize the public health risk from consuming water intended for drinking and from exposure to recreational water. Health effects assessments for waterborne pathogens can be based on a number of approaches.
|
From page 5... ...
In addition, 40-50 percent of the identified waterborne disease outbreaks remain of unknown etiology. A substantial effort to determine the potential health risks associated with consumption of drinking water has been going on since the late 1990s.
|
From page 6... ...
More specifically, the link between pathogens and their potential indicators, and among pathogens, indicators, and adverse health outcomes, would be strengthened by including in comprehensive and adequately funded studies, epidemiologic measurements of health outcomes, measurements of pathogens in clinical specimens, as well as measurements of pathogens and their potential indicators in relevant water samples. · Additional epidemiologic studies are needed to look at the association between water consumption and gastrointestinal illness in groundwater systems, and to correlate water quality data (pathogens and indicators)
|
From page 7... ...
For these reasons, existing and candidate indicator organisms should have ecologies and responses to environmental variations that are similar to those of the pathogenic organisms whose presence they are supposed to be indicating. The committee provides the following recommendations to improve understanding of the ecology and evolution of waterborne pathogens, as related to the development of new and effective indicators of microbial contamination: · Bacteria, viruses, and protozoa have evolved mechanisms that facilitate their rapid response to environmental changes and may influence their infectivity and pathogenicity.
|
From page 8... ...
A suite of indicators and indicator approaches is required for different applications and different geographies. For almost 40 years, Bonde's attributes of an ideal indicator have served as an effective model of how a fecal contamination index of public health risk and treatment efficiency should function (see Box 4-1)
|
From page 9... ...
transport to pathogens · Present in greater numbers than pathogens · Specific to a fecal source or identifiable as to source of origin Attributes of Methods · Specificity to desired target organism · Broad applicability · Precision · Adequate sensitivity · Rapidity of results · Quantifiable · Measures viability or infectivity · Logistical feasibility address all sources of contamination, have not been conducted in enough geographic locations, and do not address chronic exposure. Many reported failures of beach water quality standards are associated with nonpoint source contamination, but the epidemiologic studies used to establish recreational bathing water standards have been based primarily on exposure to point source contamination dominated by human fecal material.
|
From page 10... ...
Public health risk from exposure to fecally contaminated water is likely to vary depending on whether high indicator concentrations resulted from animal or human sources, and microbial source tracking tools will allow public health managers to incorporate that distinction into their decision making. · Models that predict future water quality conditions, based on factors such as rainfall, are potentially valuable tools for warning the public before exposure occurs, but the scientific foundation for these models has to be enhanced before they can be widely used.
|
From page 11... ...
Development of new and improved methods has been funded substantially for only a few pathogens, specifically those targeted for regulation in drinking water. Greater and more consistent efforts should be made to support methods development for new and emerging microbial detection technologies, for many more pathogens, and for new and improved candidate indicators of waterborne pathogens.
|
From page 12... ...
Based on these conclusions, the committee provides the following recommendations regarding the development of new biological measurement opportunities in the field of microbial water quality assessment: · A specific program on promising research methodologies for waterborne microorganisms of public health concern should be supported by EPA and other organizations concerned with microbial water quality. Such methodologies need not be microorganism specific, but should be application specific, focusing on the desirable attributes of the method.
|
From page 13... ...
are matched to the requirements of a particular microbial water quality application. In this regard, the committee recommends the use of a phased, threelevel monitoring framework, as illustrated in Figure ES-1, for selecting indicators and indicator approaches for waterborne pathogens.
|
From page 14... ...
Many of the new and emerging biological measurement methods and detection technologies described in Chapter 5 and Appendix C will be useful at this stage of investigation. Since confirmation studies focus on assessing health risk, the most important indicator biological attributes during this phase are correlation with contamination sources and transport or survival behavior similar to pathogens.
|
From page 15... ...
The preceding discussion is focused on microbial water quality monitoring to support risk management, not the risk management actions themselves which are largely beyond the scope of this report. Appropriate risk management decisions depend not only on the results of monitoring but on the application the monitoring is designed to address.
|
From page 16... ...
· Consistent with previous related recommendations, EPA should invest in comprehensive epidemiologic studies to (1) assess the effectiveness and validity of newly developed indicators or indicator approaches for determining poor microbial water quality and (2)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.