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From page 1... ... Executive Summary Americans drink millions of gallons of tap water each day, usually with an unquestioning faith in its safety. Indeed, the provision and management of safe drinking water throughout the United States have been major triumphs of public health practice since the turn of the twentieth century. Read the entire page →
From page 2... ... monitoring need to be conducted for most of the contaminants on the 1998 CCL, the list is also used to prioritize these related activities. This is the third report by the Committee on Drinking Water Contaminants (jointly overseen by the National Research Council's [NRC's] Read the entire page →
From page 3... ... to explore the feasibility of developing and using mechanisms for identifying emerging microbial pathogens (using what the committee now terms virulencefactor activity relationships, or VFARs) for research and regulatory activities -- also as recommended in the second report. Read the entire page →
From page 4... ... can be made about policy decisions. These limitations are identified and discussed in Chapter 2 and provide a foundation for much of this report. Read the entire page →
From page 5... ... FIGURE ES-1 Recommended two-step process for developing future CCLs. interim regulations for any drinking water contaminant that is determined to pose an "urgent threat" to humans. Read the entire page →
From page 6... ... that to be scientifically sound as well as publicly acceptable, the process for developing future CCLs must depart considerably from the process used to develop the first CCL. The committee recommends that the process for selecting contaminants for future CCLs be systematic, scientifically sound, and transparent. Read the entire page →
From page 7... ... people with poor nutrition, and people experiencing socioeconomic hardships and racial or ethnic discrimination. Universe to PCCL While the contaminants included on the first (1998) Read the entire page →
From page 8... ... • As an integral part of the development process for future PCCLs and CCLs, all information used from existing or created databases or lists should be compiled in a consolidated database to provide a consistent mechanism for recording and retrieving information on the contaminants under consideration. Such a database could function as a "master list" that contains a detailed record of how the universe of potential contaminants was identified and how a particular PCCL and its corresponding CCL were subsequently created. Read the entire page →
From page 9... ... FIGURE ES-2 Conceptual approach to identifying contaminants for inclusion on a PCCL through the intersection of their demonstrated and potential occurrence in drinking water and their ability to cause adverse health effects. Note, the sizes of the intersections and rings are not drawn to scale and do not represent an estimate of the relative numbers of contaminants in each area. Read the entire page →
From page 10... ... data. The committee recommends that the first four of these should be used as indicators of demonstrated occurrence and information that comes from items 5 to 7 should be used to determine potential occurrence. Read the entire page →
From page 11... ... humans. Neural networks and similar methods start with prototypes (a "training set") Read the entire page →
From page 12... ... consideration. Furthermore, the scoring metrics and related considerations for each attribute should be viewed in an illustrative manner. Read the entire page →
From page 13... ... of "nondetect" observations. In addition, EPA may want to consider providing other measures of concentration in water supplies such as the 95th percentile of contaminant concentration. Read the entire page →
From page 14... ... in a sacrifice of generalization (predictive) ability. Read the entire page →
From page 15... ... but rather derives from the difficulty in elucidating the mapping. The committee notes that the underlying mapping in a neural network classifier can be examined just as one would conduct experiments to probe a physical system in a laboratory. Read the entire page →
From page 16... ... Virulence-Factor Activity Relationships A virulence-factor activity relationship is the known or presumed linkage between the biological characteristics of a microorganism and its real or potential ability to cause harm (pathogenicity) Read the entire page →
From page 17... ... microbial contamination of drinking water are also reviewed in Chapter 6. Framework The central concept is to use microbial characteristics to predict virulence through VFARs. Read the entire page →
From page 18... ... Feasibility For the VFAR concept to be ultimately adopted and used by EPA in the agency's drinking water program, it must be feasible. This committee strongly believes this to be the case. Read the entire page →
From page 19... ... • Establish a scientific VFAR Working Group on bioinformatics, genomics, and proteomics, with a charge to study these disciplines on an ongoing basis and periodically inform the agency as to how these disciplines can affect the identification and selection of drinking water contaminants for future regulatory, monitoring, and research activities. The committee acknowledges the importance of several practical considerations related to the formation of such a working group within EPA, including how it should be administered and supported (e.g., logistically and financially) Read the entire page →

From page 1...

... Executive Summary Americans drink millions of gallons of tap water each day, usually with an unquestioning faith in its safety. Indeed, the provision and management of safe drinking water throughout the United States have been major triumphs of public health practice since the turn of the twentieth century.