Full Description

The CCL classification process involves three major stages. The first stageidentifies chemicals that are present in or have the potential to be present in drinkingwater, or chemicals that have demonstrated or have potential adverse health effects. Takinginto account both the occurrence and adverse health effects data, the second stagenarrows the pool of candidates to a preliminary CCL (PCCL). The PCCL is anintermediate step for contaminants that will be scrutinized in more detail in thedevelopment of the CCL. The third stage of the process involves analyzing contaminantson the PCCL to develop the CCL. The first two stages of analyses - data evaluation andthe screening process are discussed below.The first step in developing the universe of potential drinking water chemicalcontaminants was to identify and retrieve data sources that have information aboutoccurrence of chemicals in water, a link or pathway to drinking water, and health effects.Using this as the initial criteria, 284 data sources were identified which includedhundreds of thousands of chemicals. These sources contained disparate types of data fora variety of chemicals. These data sources were further evaluated to identify the mostrelevant sources that provided unique data and information on a chemical's potential tooccur in drinking water and cause adverse health effects. Assessment factors weredeveloped to prioritize the data sources and identify chemicals to consider in the CCLprocess. Each source was evaluated for its relevance, completeness, redundancy, andretrievability. Using the assessment factor criteria, 39 data sources were chosen toconstruct the CCL universe of chemical contaminants.The goals of the second stage are to screen the chemicals from the 39 data sourceson a limited set of available data elements representative of health effects and occurrence,and to select contaminants for the PCCL based upon a level of concern. Available dataelements that represent health effects include the reference dose (RfD), lowest observedadverse effect levels (LOAEL), lethal dose (LD50), and cancer classifications. The dataelements representative of occurrence include: measured values in finished, ambient andsource waters, release/use data (lbs/year, number of States), production data (lbs/year), andpersistence measures (half-life, biodegradation rates). Utilizing available occurrenceand health effects data; U.S. Environmental Protection Agency (USEPA) is examining the impact of several criteria that could be usedto select contaminants for inclusion on the PCCL. Includes abstract only.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 1File Size: 1 file , 45 KB