Indicators for Waterborne Pathogens (2004) / Chapter Skim
Currently Skimming:
1 Introduction and Historical Background
1 Introduction and Historical Background
Pages 17-52
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From page 17... ...
Through these historical efforts and owing to ongoing advances in water and wastewater treatment and source water protection, the United States has secured and maintains one of the cleanest and safest supplies of drinking water in the world. Starting in 1920, national statistics on waterborne disease outbreaks caused by microorganisms, chemicals, or of unknown etiology have been collected by a variety of researchers and federal agencies (Lee et al., 2002)
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, aquatic microbial ecology, microbial risk assessment, water quality standards and regulations, environmental engineering, biochemistry and molecular biology, detection methods, and epidemiology and public health. The report's conclusions and recommendations are based on a review of relevant technical literature, information gathered at four committee meetings, a public workshop on indicators for waterborne pathogens (held on September 4, 2002)
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Lastly, this report does not address public swimming and wading pools that are regulated by state and local health departments whose disinfection practices vary widely from place to place. This chapter provides an introduction to the public health importance of waterborne pathogens; a brief summary of key federal laws, regulations, and programs concerning microbial water quality monitoring and especially the use of indicator organisms; the historical development and current use of microbial indicators for waterborne pathogens; and the current status of waterborne disease outbreaks and endemic disease.
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positive for TC Surface Water Turbidity Measure of filter http://www.epa.gov/ Treatment Rule efficiency and source safewater/mdbp/ (SWTR) , as water quality ieswtrfr.pdf amended by the Disinfectant Nondetection of a following rules residual disinfectant residual indicates a distribution system problem
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Total culturable facilitate Applicable for PWSs viruses development of the serving 100,000 TC Long-Term 2 persons to provide FC ESWTR treatment data and monitor disinfection by-products and source water quality parameters Long-Term 2 Cryptosporidium Determine minimum www.epa.gov/ ESWTR E coli treatment level safewater/lt2/ (proposed rule)
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Impaired Varies by state Determine if waters http://www.epa.gov/ Waters List and meet state-determined owow/tmdl/ Total Maximum ambient water quality http://www.epa.gov/ Daily Load standards owow/tmdl/ (TMDL) Program pathogen_all.pdf http://www.epa.gov/ owow/tmdl/examples/ pathogens.html http:///www.epa.gov/ owow/tmdl/ 2002wqma.html SOURCE: EPA, 2002d.
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Under the SDWA, microbial contamination is regulated primarily under the Total Coliform Rule (TCR) and the Surface Water Treatment Rule (SWTR)
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In addition to measures authorized before 1972, the CWA authorizes water quality programs; requires federal effluent limitations for wastewater discharges to surface waters and publicly owned treatment works (i.e., municipal sewage treatment plants) and ambient water quality standards;3 requires permits for discharge of pollutants4 into waters of the United States; provides enforcement mechanisms; and authorizes funding for wastewater treatment works construction grants and state revolving loan programs, as well as funding to states and tribes for their water quality programs.
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of the CWA, Section 303(s) of the CWA requires states to identify waters not meeting ambient water quality standards and include them on their 303(d)
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reports, states rely primarily on bacterial indi 7Although the reported terminology for "pathogens" varies considerably and in many cases is unspecified, it includes primarily variations in coliforms but also includes Escherichia coli and enteric viruses (EPA, 2000a)
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TMDL process in any detail. Rather, please refer to the 2001 NRC report Assessing the TMDL Approach to Water Quality Management, which reviews the program at the request of Congress and provides many recommendations for its comprehensive improvement.
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To help address these and related issues, in 1999 EPA issued Action Plan for Beaches and Recreational Waters (Beach Action Plan) , a multiyear strategy to improve the monitoring of recreational water quality and the communication of public health risks associated with pathogen-contaminated recreational rivers, lakes, and ocean beaches (EPA, 1999)
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waters through improved water quality programs, scientific advancements, and risk communication. Moreover, it is an initial effort by EPA to begin to integrate the traditionally separate microbial assessment regulations, programs, and use of differing indicators of waterborne pathogens (see Tables 1-1 and 1-2)
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is used widely as an indicator of fecal contamination of drinking water, recreational waters, and shellfishing waters, and as a measure of water treatment effectiveness. Enterococci are typically used as indicators of fecal contamination of recreational waters (EPA, 1986, 2002b)
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. Enterococci and their taxonomically broader predecessor group, the so-called fecal streptococci, as well as Clostridium perfringens and its broader predecessor group the sulfite-reducing clostridia, have a long history of use and refinement as bacterial indicators of fecal contamination, as summarized below.
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Fecal streptococci and enterococci were further evaluated as fecal indicators of water quality in the 1940s and 1950s by several groups. Efforts were made to improve the medium for their detection, with the goal of detecting those microorganisms of primarily fecal origin (Burman, 1961; Kenner et al., 1961; Litsky et al., 1955; Mallmann and Seligman, 1950; Slanetz and Bartley, 1957)
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. In addition, their apparent absence in unpolluted environmental waters in Hawaii supported their use as a fecal indicator of water quality in this tropical region (Fujioka, 2001)
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In 1956, the City of Los Angeles conducted a survey of standards for recreational waters in 13 jurisdictions (Garber, 1956) .12 The State of Illinois used enterococci,13 while the remaining jurisdictions used total coliforms.
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Thus, the NTAC (1968) recommended the following criteria for recreational waters: geometric mean <200 fecal coliforms per 100 mL; 90 percent of samples <400 fecal coliforms per 100 mL.
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Detection methods have continued to evolve over the last several decades for the bacteria variously referred to as fecal streptococci, enterococci, and intestinal enterococci in recreational waters (e.g., Messer and Dufour, 1998)
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Thus, while the presence of coliforms could still be taken as a sign of fecal contamination, the absence of coliforms could no longer be taken as assurance that water was uncontaminated. Expansion Beyond Indicators for Human Fecal Contamination: Zoonoses and Protozoan Pathogens Most, but not all, pathogens of concern in drinking water are spread by the fecal-to-oral route.
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CURRENT STATUS OF WATERBORNE OUTBREAKS AND ENDEMIC DISEASE Even though the association between water quality and disease has been recognized for more than a hundred years, the transmission of waterborne diseases is still a major public health concern in developed nations. In the United States, national statistics on outbreaks associated with drinking water have been collected since 1920 (Craun, 1986)
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A more detailed description of the National Waterborne Diseases Outbreak Surveillance System (WBDOSS) and of the various epidemiologic studies of endemic disease associated with drinking and recreational waters is provided in Chapter 2.
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SOURCE: Adapted from Lee et al., 2002. drinking water quality.
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Figure 1-2 also emphasizes the relatively few number of reported surface water outbreaks in this period, which again might be a reflection of EPA's regulations targeted at surface water systems and the ability of large water utilities to meet or exceed EPA standards. Small water utilities, often using groundwater sources, have fewer resources and are more likely to have difficulties meeting increasingly stringent water quality standards (NRC, 1997)
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While gastrointestinal outbreaks associated with bacteria were most commonly reported in ambient recreational waters, outbreaks of dermatitis and cases of primary amoebic meningoencephalitis were associated only with recre ational water. The "other" illness category includes one outbreak each of lep tospirosis, legionellosis, and keratitis in ambient waters and one outbreak associ ated with algae in a surface water system.
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The amendments did not specify which waterborne diseases were to be studied, and after conducting several workshops, the two agencies determined that the health outcome that would be studied in this initial effort would be gastrointestinal disease. Based on this interagency agreement, CDC has funded cooperative agreements with academic institutions to conduct two pilot intervention trials of home water treatment in households and one full-scale intervention trial along with several related "nested" epidemiology studies to help maximize the benefit of the large-scale trial.
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beginning with the 1998-1999 cycle. As part of the BEACH Program, EPA will be conducting new epidemiologic studies intended to correlate water quality with human health effects.
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For example, some indicators will be more useful in temperate zones than in the subtropics, some will be more effective in surface water than in groundwater sources of drinking water, and some will be more useful in freshwaters than in marine recreational waters. Finally, a different set of indicator attributes will come into play when the effectiveness of treatment or the integrity of a drinking water distribution system is at issue (though the latter are excluded from explicit consideration in the committee's charge)
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Better detection methods in clinical specimens as well as in water samples have increased the identification of pathogens, most notably viruses. Despite these improvements, the etiologic agent remains unknown for a large percentage of drinking water and recreational water outbreaks, making the selection and use of indicators for waterborne pathogens very complex.
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2001. Indicators of microbial water quality.
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1998a. Bacterial Water Quality Standards for Recreational Waters (Freshwater and Marine Waters)
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2003a. Bacterial Water Quality Standards for Recreational Waters (Freshwater and Marine Waters)
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1990. Waterborne disease outbreaks, 1986-1988.
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1999. Drinking water quality standards, regulations and goals.
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1953. Studies of bathing water quality and health.
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