EWG's Tap Water Database — 2021 UPDATE

picture of test tube and beaker in laboratory


October 2019


Atrazine is one of the most widely and heavily used herbicides in American agriculture. The Environmental Protection Agency estimates that about 70 million pounds are applied to crops every year. Atrazine-laced runoff from farm fields pollutes streams, rivers and groundwater, which many communities depend on for drinking water. It resists degradation from heat and sunlight.

EWG research shows that atrazine is the most commonly detected pesticide in tap water, at concentrations that can be higher than what the federal legal allows. Water utilities struggle to remove atrazine, particularly in the spring, when millions of pounds of the chemical are applied to corn and soybean fields.

In 2012, Syngenta, the herbicide’s sole manufacturer, settled for $105 million a lawsuit filed by more than 1,000 Midwestern water providers over the cost of removing atrazine from drinking water – a figure some utilities said would not begin to cover the cost of removal.

Click here to see the nationwide testing results for atrazine.

How does atrazine harm people?

Atrazine is a hormone disrupter that even at low doses affects the human reproductive system, posing the greatest risk during pregnancy and early childhood. Research suggests it acts by depressing a hormone known as LH, which leads to increased production of estrogen and prolactin in females and to changes in testosterone levels in males.

University of California, Berkeley biologist Tyrone Hayes, Ph.D., has reported that low-level exposures can disrupt frogs’ hormone systems.

In 2011, the EPA Scientific Advisory Panel reviewed the human health effects of atrazine and concluded that there is suggestive evidence showing that atrazine can increase the risk of ovarian cancer, non-Hodgkin lymphoma, hairy-cell leukemia and thyroid cancer.

Studies suggest human health may be affected by low levels of atrazine in drinking water:

What are the health guidelines for atrazine?

The EPA’s legal limit allows up to 3 parts per billion, or ppb, of atrazine in treated tap water.

In 1999 the California Office of Environmental Health Hazard Assessment set a public health goal of 0.15 ppb for atrazine in drinking water, a level based on a study finding increased rates of breast cancer in rats exposed to the chemical. California’s legal maximum for atrazine in tap water is 1 ppb. Europe has banned all pesticides in drinking water, which led atrazine to be phased out in 2003.

As scientists continue to study endocrine disruptors, more information becomes available that shows that these contaminants are harmful even at very low levels. EWG’s health guideline of 0.1 ppb for atrazine was based on epidemiological studies of exposure to atrazine in drinking water. This health guideline protects against hormone disruption and harm to the developing fetus and the reproductive system.

What can I do to address the risks of atrazine in my drinking water?

The most important thing to do is get more information about whether your drinking water contains atrazine. You can:


Associated Press. Syngenta Pays Millions in Settlement to Farming States. The Topeka Capital-Journal, 2013. Available at

California Office of Environmental Health Hazard Assessment. Public Health Goal for Atrazine in Drinking Water. 1999. Available at

C. Chevrier et al. Urinary Biomarkers of Prenatal Atrazine Exposure and Adverse Birth Outcomes in the PELAGIE Birth Cohort. Environmental Health Perspectives, 2011, 119(7):1034–1041.

L.A. Cragin et al. Menstrual Cycle Characteristics and Reproductive Hormone Levels in Women Exposed to Atrazine in Drinking Water. Environmental Research, 2011, 111(8):1293–1301.

E. Mendez. Presentation to the Scientific Advisory Panel. Atrazine Re-Evaluation: Scientific Considerations in Potential Sensitivity of Infants & Children. Environmental Protection Agency, Office of Pesticide Programs, Health Effects Division, July 26–29, 2011.

Environmental Protection Agency Science Advisory Panel. Meeting Minutes of the FIFRA Scientific Advisory Panel meeting held July 26–28, 2011 on the Re-Evaluation of the Human Health Effects of Atrazine: Review of Non-Cancer Effects, Drinking Water Monitoring Frequency and Cancer Epidemiology. Oct. 26, 2011.

EPA, Office of Pesticides, Environmental Fate and Effects Division. Refined Ecological Risk Assessment for Atrazine. April 2016. Available at

European Commission. Review Report for the Active Substance Atrazine. Finalized in the Standing Committee on the Food Chain and Animal Health at its meeting on Oct. 3, 2003 in support of a decision concerning the non-inclusion of atrazine in Annex I of Directive 91/414/EEC and the withdrawal of authorisation for plant protection products containing this active substance. European Commission Health and Consumer Protection Directorate-General, 2003, SANCO/10496/2003-final.

T. Hayes et al. Demasculinization and Feminization of Male Gonads by Atrazine: Consistent Effects Across Vertebrate Classes. Journal of Steroid Biochemistry and Molecular Biology, 2011, 127:64-73.

M.G. Rhoades et al. Atrazine and Nitrate in Public Drinking Water Supplies and Non-Hodgkin Lymphoma in Nebraska, USA. Environmental Health Insights, 2014, 7:15-27.

L.T. Stayner et al. Atrazine and Nitrate in Drinking Water and the Risk of Preterm Delivery and Low Birth Weight in Four Midwestern States. Environmental Research, 2017, 152:294-303.