Definition__Mean Trichloroethene Levels for Utah__ [[br]]
1) Yearly distribution of number of community water systems (CWS) by mean trichloroethene (TCE) concentration [[br]]
2) Yearly distribution of number of people served by CWS by mean TCE concentration
__Maximum Trichloroethene Levels for Utah__ [[br]]
3) Yearly distribution of number of CWS by maximum TCE concentration [[br]]
4) Yearly distribution of number of people served by CWS by maximum TCE concentration
Numerator1) Count of community water systems categorized by mean TCE concentration for each year reported (cut-points: <=5, >5 ug/L TCE, Not Detected)
2) Number of people served by community water systems categorized by mean TCE concentration for each year reported (cut-points: <=5, >5 ug/L TCE, Not Detected)
3) Count of community water systems categorized by maximum TCE concentration for each year reported (cut-points: <=5, >5 ug/L TCE, Not Detected)
4) Number of people served by community water systems categorized by maximum TCE concentration for each year reported (cut-points: <=5, >5 ug/L TCE, Not Detected)
DenominatorNot applicable. There are no rate measures in this indicator.
Data Interpretation IssuesA community water system (CWS) is a public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. These calculations include all available data which varies by year and water system. Population data for each community water system are estimates based on number of connections. Inconsistent outliers and other data errors were not included in calculations in order to provide a more accurate representation of water quality. Data reported to other sources, such as the U.S. Environmental Protection Agency (EPA), may differ slightly. This data does not include information about private water sources such as well water or tribal water systems.
The current measures are derived for CWS only. Private wells may be another source of population exposure to TCE. Transient non-community water systems, which are regulated by EPA, also may be an important source of TCE exposure. Measures do not account for the variability in sampling, numbers of sampling repeats, and variability within systems. Concentrations in drinking water cannot be directly converted to exposure because water consumption varies by climate, level of physical activity, and between people. Due to errors in estimating populations, the measures may overestimate or underestimate the number of affected people. (From the National Environmental Public Health Tracking Network [NEPHTN] Nationally Consistent Data and Measures [NCDM] TCE indicator document, version 5)
Ground water systems may have multiple wells with different TCE concentrations that serve different parts of the population. Compliance samples are taken at each entry point to the distribution system. In systems with separate wells serving some branches or sections of the distribution system, the system mean would tend to underestimate the TCE concentration of people served by wells with higher TCE concentrations. Exposure may be higher or lower than estimated if data from multiple entry points for water with different TCE levels are averaged to estimate levels for the CWS. (From the NEPHTN NCDM TCE indicator document, version 5)
Why Is This Important?People drink and use water every day. The majority of Americans are provided with high quality drinking water. About 90% of people in the U.S. get their water from a community water system versus a smaller water supply, such as a household well. The U.S. Environmental Protection Agency (EPA) sets regulations for treating and monitoring drinking water delivered by community water systems. Currently, there are water quality standards and monitoring requirements for over 90 contaminants. Drinking water protection programs play a critical role in ensuring high quality drinking water and protecting the public's health.
Because people drink and use water every day, contaminants in drinking water have the potential to affect many people. The number of people served by a community water system varies from as low as 25 to hundreds of thousands. Community water systems in the U.S. provide among the highest quality drinking water in the world. However, some contaminants are present at low levels, and it is still possible that drinking water can become contaminated at higher levels. If a person is exposed to a high enough level of a contaminant, they may become ill.
Trichloroethene (TCE) is a volatile halogenated short-chain hydrocarbon. TCE is used primarily as an industrial degreaser, solvent, and in the synthesis of other chemicals. In the past, it was used in dry cleaning, food processing, household cleaners, and as a general anesthetic. TCE is produced and used in high volumes in the U.S. and has been detected in urban and ambient air and occasionally soils and drinking water most likely contaminated by industrial discharge (Moran et al., 2007; Rowe et al., 2007). Because of its volatility, this solvent does not persist in the soil or water following the discontinuation of contamination. (From the National Environmental Public Health Tracking Network [NEPHTN] Nationally Consistent Data and Measures [NCDM] TCE indicator document, version 5)
TCE does not occur naturally in the environment. However, it has been found in underground water sources and many surface waters as a result of the manufacture, use, and disposal of the chemical. Drinking or breathing high levels of TCE may cause nervous system effects, liver and lung damage, abnormal heartbeat, coma, and possibly death (ATSDR, 2003). Inhalation is the most common exposure route for the general population including indoor sources from paints, adhesives, and cleaning solutions. Volatilization from contaminated water (e.g., shower water) as well as the use of household products containing this solvent can result in higher indoor air concentrations than outdoor (ATSDR, 1997b; Martin et al., 2005). (Modified from the NEPHTN NCDM TCE indicator document, version 5)