AWWA WQTC64182

The Safe Drinking Water Act (SDWA), as amended in 1996, requires the U.S. EnvironmentalProtection Agency (USEPA) to publish a list of microbial and chemical contaminants that areknown or anticipated to occur in public water systems and which may require regulation. Thislist is known as the Contaminant Candidate List (CCL) and is published every five years. TheCCL is used to prioritize research and data collection efforts on microbial and chemicalcontaminants to help in determining whether particular contaminants should be regulated.Microorganisms placed on the CCL are considered to be potential agents of waterborne diseasebut there is insufficient information to determine whether they represent true waterborne threatsto public health. In order to determine which contaminants to regulate, the USEPA must gatherdata to determine if these pathogens represent a health risk, and if by regulating a specificcontaminant, the health risk would be minimized. The main areas in which significant data gapsexist for CCL microorganisms are human health effects, effectiveness of water treatmentpractices, development of analytical methods, and occurrence in water. The first CCL wasdeveloped within a short time period and was based on existing knowledge and expert judgment,particularly for the microbial contaminants (USEPA, 1998). These contaminants were identifiedwith assistance from a panel of expert microbiologists who selected potential candidates usingthe criteria of public health significance, waterborne transmission, occurrence in source water,current water treatment technologies, and adequacy of analytical methods for detecting anorganism. In 2003, Acanthamoeba was removed from the CCL because regulating it as a contaminantwould not have resulted in reduced health risk since the primary adverse health effects arecaused by improper care of contact lenses. Consequently, USEPA issued guidance encouragingcontact lens wearers to follow proper cleaning and rinsing practices. Since the first CCL waspublished, the USEPA has sought the advice of the National Academy of Sciences (NAS) andthe National Drinking Water Advisory Council (NDWAC) to enhance and refine the process toselect contaminants to increase the objectivity, robustness, and transparency of the process. TheNAS recommendation called for a single approach to evaluating chemical and microbialcontaminants for the CCL (NRC, 2001). The NDWAC deliberations noted that chemicals andmicroorganisms behave in markedly different ways in the environment and within the humanhost. The NDWAC recommendations for evaluating microorganisms differed from the NAS andaddressed the types of data that should be considered, new and emerging technologies that mayprovide data for consideration, how to account for the differences between chemical andmicrobial contaminants, and decision tools and methods to help select contaminants for inclusionon the CCL in a transparent manner. The NDWAC also recognized that microbial contaminantsare characterized differently in the literature and available databases, therefore the evaluationmight need to rely more on clinical and epidemiological data (NDWAC, 2004).The second CCL was published in 2005 and contained the same microbes as CCL1 minusAcanthamoeba (CCL2; USEPA 2005), and a draft of the third CCL is scheduled for 2008.However, the process used and rationale for placing microbes on the CCL are not clearlyunderstood by the drinking water community. Comments received by the USEPA in response tothe draft CCL2 indicated that some individuals and organizations within the water industry,while supporting the concept of the CCL, have a variety of concerns about the process. Forexample, some responses focused on the omission of particular contaminants (e.g.,enterotoxigenic Escherichia coli), automatic rolling over of CCL1 into CCL2, lack of updates onongoing CCL-related research, and development of a more pragmatic approach to selectin

Product Details

Edition:

Vol. - No.

Published:

11/01/2006

Number of Pages:

16

File Size:

1 file , 400 KB