Important Facts for Drinking Water: Atrazine

Definition

__Mean Atrazine Levels for Utah__[[br]] 1) Yearly distribution of number of community water systems (CWS) by mean atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected) 2) Yearly distribution of number of people served by CWS by mean atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected) 3) Quarterly distribution of number of CWS by mean atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected) 4) Quarterly distribution of number of people served by CWS by mean atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected) __Maximum Atrazine Levels for Utah__[[br]] 5) Yearly distribution of number of CWS by maximum atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected) 6) Yearly distribution of number of people served by CWS by maximum atrazine concentration (cut-points: <=3, >3 ug/L atrazine, Not Detected)

Numerator

1) Count of community water systems categorized by mean atrazine concentration for each year reported 2) Number of people served by community water systems categorized by mean atrazine concentration for each year reported 3) Count of community water systems categorized by mean atrazine concentration for each quarter reported 4) Number of people served by community water systems by county categorized by mean atrazine concentration for each quarter reported 5) Count of community water systems categorized by maximum atrazine concentration for each year reported 6) Number of people served by community water systems categorized by maximum atrazine concentration for each year reported

Denominator

Not applicable.

Data Interpretation Issues

The current measures are derived for community water systems (CWS) only. Private wells are another important source of population exposure to atrazine in some agricultural regions. Transient non-community water systems, which are regulated by EPA, may also be an important source of atrazine exposure. Measures do not account for the variability in sampling, numbers of sampling repeats, and variability within systems. Concentrations in drinking water cannot be converted directly to exposure, because water consumption varies by climate, level of physical activity, and between people (EPA 2004). 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 [NEPTHN] Nationally Consistent Data and Measures [NCDM] atrazine indicator document version 10) Ground water systems may have many wells with different atrazine 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 atrazine concentration of people served by wells with higher atrazine concentrations. Exposure may be higher or lower than estimated if data from multiple entry points for water with different atrazine levels are averaged to estimate levels for the CWS. (Modified from the National Environmental Public Health Tracking Network [NEPTHN] Nationally Consistent Data and Measures [NCDM] atrazine indicator document version 10)

Why Is This Important?

People drink and use water every day. Therefore, contaminants in drinking water have the potential to affect many people. The number of people served by a community water system (CWS) varies from as low as 25 to hundreds of thousands. CWS 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. The majority of Americans are provided with high quality drinking water. About 90% of people in the U.S. get their water from a CWS 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. Atrazine is an herbicide that was developed to control broadleaf and grassy weeds. Because of this application, atrazine is capable of entering water systems and sources through agricultural runoff. Some people who drink water containing atrazine well in excess of the maximum contaminant level (MCL) for many years can experience problems with their cardiovascular system or reproductive difficulties. (EPA, [http://water.epa.gov/drink/contaminants/basicinformation/atrazine.cfm]) Atrazine is the common name for an herbicide that is widely used to kill weeds. It is used mostly on farms. Pure atrazine is an odorless, white powder that is not very volatile, reactive, or flammable. It will dissolve in water. Atrazine is made in the laboratory; it does not occur naturally. (From the National Environmental Public Health Tracking Network [NEPTHN] Nationally Consistent Data and Measures [NCDM] atrazine indicator document version 10) Any atrazine that is washed from the soil into streams and other bodies of water will stay there for a long time because chemical breakdown is slow in rivers and lakes. It also will persist for a long time in groundwater. This is one reason why atrazine is commonly found in the water collected from drinking water wells in some agricultural regions. (From the National Environmental Public Health Tracking Network [NEPTHN] Nationally Consistent Data and Measures [NCDM] atrazine indicator document version 10)