National Drinking Water Database
Atrazine in Missouri
Atrazine is an endocrine-disrupting herbicide used on corn, sugarcane and sorghum; it is associated with adverse reproductive effects and toxicity to the immune system. [read more]
Atrazine is the most commonly used weed killer in U.S. agriculture, and is found in the tap water of 10 million people in corn-belt states alone. An estimated 76.5 million pounds of atrazine is applied annually in the U.S., mostly on corn, sugarcane and sorghum (U.S. Environmental Protection Agency (USEPA) 2003b). France, Germany and Italy have all banned the use of atrazine, while the United States continues its use (Sass 2006).
Drinking water contamination with atrazine is due to runoff from herbicide used on row crops (USEPA 2009b).
In laboratory animals, atrazine causes significant reproductive problems, many mediated by the hormone system. In rats or dogs, atrazine alters reproductive cycling and causes damage to the prostate, breast or mammary gland (including causing tumors), bone marrow, heart and brain (USEPA 2003a).
Atrazine has an adverse effect on normal hormonal function in amphibians and mammals (reviewed in Natural Resources Defense Council (NRDC) 2009). There is strong evidence that arazine disrupts a critical period of mammary gland growth, induces reproductive tract alterations, and impacts the timing of puberty (Rayner 2004, 2005, 2007; Enoch 2007). Atrazine is known to induce mammary tumors in rats, consistent with its action as a low-dose endocrine disruptor (WHO 2004a; Cooper 2007). Research from the Reproductive Toxicology Division of the Environmental Protection Agency found that atrazine and its metabolites act on the Hypothalamic-Pituitary-Adrenal neuroendocrine pathway and cause significant, acute increases in circulating adrenocorticotropic hormone (ACTH), corticosterone and progesterone (Powers Fraites 2009).
Multiple studies have found that exposure to low concentrations of atrazine in water causes deformities in frogs, including hermaphroditism (individuals with both male and female sex organs), underdeveloped testes and a decrease in the number of germ cells (sperm and eggs) (Hayes, Collins 2002; Hayes, Haston 2002; Hayes 2003). Hermaphroditism is extremely rare and was not detected in any unexposed frogs (Hayes, Collins 2002). The level that causes hermaphroditism, 100 parts per trillion, is commonly found in corn belt tap water and is 30 times less than the legal maximum contaminant level (MCL) for atrazine of three parts per billion (USEPA 2003a).
Recent research has also found atrazine to damage the immune system in amphibians and mammals (Rohr 2008; Rowe 2008). Atrazine suppresses immune defense in tadpoles and adult frogs, making them more susceptible to parasite infections (Brodkin 2007; Rohr 2008). Young rats and mice exposed to atrazine during fetal development and through the mother's milk experience a significant depression of immune function (Rooney 2003; Rowe 2008). Atrazine exerts these immunotoxic effects by acting directly on the immune cells involved in defense against pathogens (Pinchuk 2007).
Scientists at the University of South Florida conducted a meta-analysis of atrazine ecotoxicity studies and found consistent adverse health effects of atrazine on freshwater fish and amphibians (Rohr 2009). To date, EPA has not considered the extensive data for atrazine toxicity in amphibians when re-evaluating acceptable drinking water levels for humans (USEPA 2003b), although the Agency recently committed to "take a hard look at atrazine" and conduct a "thorough review [that] will rely on transparency and sound science" (Owens 2009).
Few studies have looked at the effects of atrazine in people resulting from everyday exposures. However, workers at a Syngenta plant that produces atrazine in St. Gabriel, LA have a prostate cancer rate 3.5 times higher than the state-wide rate (MacLennan 2002, Sass 2003). For long-time workers, the prostate cancer rate was nine times higher. Atrazine has also been associated with wheezing, a condition symptomatic of airway obstruction, in pesticide applicators (Hoppin 2002).
The Most Polluted Communities in Missouri
46 water utilities reported detecting Atrazine in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies
Ranked by highest average Atrazine level
|Rank||System||Population Served||Positive test results of total reported tests||Average Level|
|9,872||18 of 22||1.03 ppb|
(0 to 3.57 ppb)
|2||Harrison Co Pwsd #1|
|900||13 of 20||0.52 ppb|
(0 to 2.03 ppb)
|2,389||17 of 22||0.52 ppb|
(0 to 1.55 ppb)
|2,360||11 of 22||0.5 ppb|
(0 to 2.18 ppb)
|8,202||5 of 22||0.5 ppb|
(0 to 5.8 ppb)
|4,800||3 of 19||0.49 ppb|
(0 to 6.9 ppb)
|7||Henry Co Pwsd #3|
|1,500||11 of 22||0.42 ppb|
(0 to 1.49 ppb)
|8||Lexington US Water Co|
Kansas City, MO
|4,450||4 of 22||0.38 ppb|
(0 to 4 ppb)
|385||11 of 21||0.37 ppb|
(0 to 2.14 ppb)
|9,408||11 of 21||0.31 ppb|
(0 to 2.08 ppb)
Health Based Limits for Atrazine
|California Public Health Goals||Defined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.||0.15 ppb|
|Maximum Contaminant Limit (MCL)||The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.||3 ppb|
|Maximum Contaminant Limit Goal (MCLG)||A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.||3 ppb|
|Drinking Water Equivalent Level||A lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.||700 ppb|
Violation Summary for Atrazine in Missouri
Data from the U.S. Environmental Protection Agency includes the following violations of federal standards in Missouri since 2004
|Violation Type||Number of Violations|
|Over maximum contaminant level, Average||4|