From Source Water to Drinking Water Workshop Summary (2004) / Chapter Skim
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3 Emerging Issues in Providing Safe Drinking Water
3 Emerging Issues in Providing Safe Drinking Water
Pages 35-46
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microbes that are either newly discovered pathogens or longestablished agents recently rendered more virulent. They further discussed a critical need by the scientific environmental research community to establish research and development priorities for developing advanced technology for environmental detection, measurement, and monitoring instrumentation technologies.
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With specific regard to these three contaminants, Nilles presented status and trend data derived from the National Atmospheric Deposition Program's National Trends Network -- a collection of monitoring sites spread across the nation -- which is supported by numerous contributors both public and private, including a wide range of federal and state agencies. A long-term network with multiple sites, it enables researchers from many agencies to use the data to correlate emission trends with potential sources and human and ecological endpoints.
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. Highest concentrations in precipitation are observed in the Indiana-Minnesota-Wisconsin corridor whereas highest deposition is observed in the southeastern United States -- a result of elevated concentration and greater amount of precipitation.
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Nitrogen oxide emissions are dominated by fossil fuel combustion, with transportation contributing 49 percent; utilities 27 percent; and industrial, commercial, or residential sources 19 percent. The highest concentrations of nitrogen oxide deposition are near areas of significant industrial activity and fossil fuel combustion, such as California, noted Nilles.
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NONREGULATED CONTAMINANTS: OLD POLLUTANTS, NEW CONCERNS; NEW POLLUTANTS, UNKNOWN ISSUES Although some emerging pollutants have recently been released into the environment, it is important to recognize that the vast majority of FIGURE 3.3 U.S. nitrate trends in precipitation have shown some sites in the United States (the West)
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Given the wide range of pollutants to which an organism is exposed, for example, as a result of drinking water, some portion of the overall risk derives from unregulated pollutants, which compose the majority of chemicals in any water sample. Scientists need to reevaluate what Not all of them are necessarily constitutes persistence.
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A study by the American Society of Civil Engineers, for example, concluded that these infrastructures currently merit nationwide grades of D and that $20 billion would be required annually merely to keep them where they are right now without further decay. It is a question not only of securing the needed financial resources, noted Daughton, but of maintaining and improving the public's confidence in water supplies.
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PATHOGENS IN WATER: ADDRESSING A PUBLIC HEALTH THREAT VIA THE POTENTIAL SYNERGISM OF THE CLEAN WATER ACT AND THE SAFE DRINKING WATER ACT It has been 10 years since the deadly Cryptosporidium outbreaks in water supplies, observed Joan Rose of Michigan State University, but we have not made as much progress during those years as we could have in addressing emerging waterborne pathogens. The zoonotic class of waterborne pathogen, of which Cryptosporidium is a classic example, is excreted in large numbers by humans and animals, survives very well in the environment, and is resistant to water treatment (see Figure 3.4)
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Drivers of increased risk of waterborne pathogens in particular include population growth and demographic changes, associated with increased generation and concentration of human wastes; the aging wastewater and drinking water infrastructures; greater exposure to emerging zoonotic agents; and climate change with precipitation, wind, and temperature shifts aiding in the transport and survival of the contaminants (see Figure 3.5)
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Outbreaks of Number FIGURE 3.6 Since 1996, the number of waterborne pathogen outbreaks in the United States has increased.
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In addition to the new pathogens being discovered every year, researchers are learning not only of the roles of infectious agents in health risk end points such as diarrhea, but also of the increasing role of infectious agents in chronic diseases such as ulcers, Guillain-Barré syndrome, and some cancers. Many of the emerging pathogenic bacteria -- including Campylobacter, Salmonella, Cryptosporidium, Giardia, Mycobacterium paratuberculosis, and new and deadly forms of the ubiquitous Escherichia coli -- are zoonotic.
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Neither act has begun regulating emerging pathogens, she noted, although the SDWA has included them on its Contaminant Candidate List for analysis of occurrence and health risk. The CWA does offer an abundance of watershed tools, however, for examining the effects of combined animal feeding operations, sanitary sewer overflows, combined sewer overflows, and septic tanks on public health.
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