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Atrazine

Atrazine is a widely used herbicide that can be applied before and after planting to control broadleaf and grassy weeds. Atrazine is a member of the triazine chemical class, which includes simazine and propazine. It is primarily used in agriculture (with the greatest use on corn, sorghum, and sugarcane). To a lesser extent, it is used on residential lawns and golf courses, particularly in Florida and the Southeast. 

The Agency's oversight of atrazine is dynamic and includes periodic re-evaluation through the registration review process. Over the years, the Agency has consulted with the FIFRA Scientific Advisory Panel (SAP) on a variety of atrazine topics.

In December 2019, EPA released the proposed interim decisions for atrazine, propazine, and simazine.

On this page:

Registration Review of Atrazine

Atrazine is undergoing registration review, our periodic re-evaluation program for existing pesticides. All documents related to the registration review of atrazine can be found in the registration review docket: EPA-HQ-OPP-2013-0266. In particular:

Upon publication of the Federal Register notice, the atrazine Proposed Interim Registration Decision will available for public comment for 60 days in docket # EPA-HQ-OPP-2013-0266. In this document EPA is proposing the following new, stronger protections to reduce exposure to atrazine.

Proposed Human Health Mitigation:
  • Rate reduction for residential turf applications
    • Reduce application rate for granular atrazine products applied to residential turf from 2.2 pounds active ingredient per acre (lb ai/A) to 2.0 lb ai/A
    • Reduce application rate for atrazine spray applications to residential turf from 2.0 lb ai/A to 1.0 lb ai/A
  • Additional personal protective equipment (PPE)
    • Combination of single- and double-layer clothing with gloves, PF10 respirators, and engineering controls
Proposed Ecological Mitigation:
  • Add mandatory spray drift reduction language
  • Add herbicide resistance management language

If at any time EPA determines there are urgent human or environmental risks from atrazine exposure that require prompt attention, we will take appropriate regulatory action, regardless of the status of the registration review process.

Additional Information

Additional information on atrazine’s registration review, reregistration, and food tolerance reassessment is available in the atrazine dockets:

Docket # at regulations.gov Docket Title and/or SAP Title
EPA-HQ-OPP-2003-0367 Atrazine Interim Reregistration Eligibility Decision (IRED)
EPA-HQ-OPP-2005-0481 2006 Triazine Cumulative Risk Assessment
EPA-HQ-OPP-2009-0759 Presentation of the Atrazine Reevaluation Plan
EPA-HQ-OPP-2009-0851 Draft Framework and Case Studies on Atrazine, Human Incidents, and the Agricultural Health Study: Incorporation of Epidemiology and Human Incident Data into Human Health Risk Assessment
EPA-HQ-OPP-2010-0125 Re-Evaluation of Human Health Effects of Atrazine: Review of Experimental Animal and In Vitro Studies and Drinking Water Monitoring Frequency
EPA-HQ-OPP-2010-0481 Re-Evaluation of Human Health Effects of Atrazine: Review of Non-Cancer Effects and Drinking Water Monitoring Frequency
EPA-HQ-OPP-2011-0399 Re-Evaluation of Human Health Effects of Atrazine: Review of Non-Cancer Effects, Drinking Water Monitoring Frequency, and Cancer Epidemiology
EPA-HQ-OPP-2012-0230 Problem Formulation for Reassessment of Ecological Risks from Use of Atrazine
EPA-HQ-OPP-2013-0266 Atrazine Registration Review

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Monitoring Atrazine in Drinking Water

Community water systems (CWS) are required, under the Safe Drinking Water Act, to monitor for atrazine.

In addition, for the past 15 years, the atrazine technical registrants have been required to monitor for atrazine in surface drinking water per the 2003 Atrazine Interim Reregistration Eligibility Decision (IRED) and the 2004 Memorandum of Agreement (MOA) between EPA and the atrazine technical registrants.

The monitoring program conducted by the atrazine technical registrants, called the Atrazine Monitoring Program (AMP), monitors approximately 150 surface water CWS, primarily in the Midwest, to determine whether concentrations of atrazine and its chemical degradates are present at a level that could potentially pose a risk to public health. Under the AMP, CWSs are selected for intensive monitoring based on a history of atrazine use and a screen of EPA's data collected under the Safe Drinking Water Act. CWSs included in the AMP are monitored on a weekly basis during peak atrazine use season and biweekly during the rest of the year.

As part of registration review and decades of study, EPA is considering amendments to the 2004 Memorandum of Agreement that would end the requirement for continued drinking water monitoring under the AMP. The totality of available atrazine monitoring data collected through the AMP is robust and comprehensive, which enabled the EPA to refine and characterize its most recent (2018) human health risk assessment. Estimates in the 2018 draft human health risk, as well as measured concentrations for community water systems, are well below the drinking water level of comparison (DWLOC) of 580 parts per billion. EPA will accept comments on the proposal to discontinue the AMP during the comment period on the Proposed Interim Decision on Atrazine.

EPA will continue to require monitoring for atrazine under the Safe Drinking Water Act.

View Atrazine Monitoring Program Data and Results.

View Atrazine Data Collected under the Safe Drinking Water Act.

Atrazine Ecological Exposure Monitoring Program

The Atrazine Ecological Exposure Monitoring Program assesses atrazine levels in streams in watersheds that are exposed to atrazine runoff from corn and sorghum production (small streams, high atrazine use areas, and vulnerable soils). This monitoring program is required by the 2003 Atrazine Interim Reregistration Eligibility Decision (IRED) and the 2004 Atrazine Memorandum of Agreement (MOA).

EPA currently regulates on an aquatic plant Concentration Equivalent Level of Concern (CE-LOC) of 10 ppb as a 60-day average concentration, which ensures that atrazine levels will not cause significant changes in aquatic plant community structure, function and productivity. 

If a watershed shows atrazine concentrations above this level of concern in any two years of monitoring, atrazine registrants must initiate watershed-based mitigation activities in concert with state or local watershed programs to reduce atrazine exposure. These mitigation activities can include, for example, education, stewardship and outreach programs for growers and distributors. A watershed can be decommissioned from the monitoring program if the 60-day running average falls below the CE-LOC for two consecutive years.

  • Since the program's inception, up to 33 watersheds have been monitored for atrazine in corn-, sorghum- and sugarcane-producing areas.
  • As of 2015, nine watersheds in five states (Iowa, Texas, Missouri, Louisiana and Nebraska) are in the monitoring program.
  • As of 2013, all sugarcane sites were decommissioned from the monitoring program.
  • The registrant has addressed exceedances by implementing label education, stewardship, and outreach programs in these watersheds, and is attempting to quantify the impact and effectiveness of the mitigation activities through a grower survey.

View Atrazine Ecological Exposure Monitoring Program Data and Results

View Atrazine Data Collected under the Safe Drinking Water Act

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Triazine Registration Review

Atrazine is chemically related to two other herbicides, simazine and propazine, which together are called "triazines." The chemical class, triazines, is currently undergoing registration review, our periodic re-evaluation program for existing pesticides.

The triazines have a common mechanism of toxicity, and therefore EPA has conducted both individual chemical and cumulative human health risk assessments.

Proposed Interim Registration Review Decisions

In December 2019, EPA released the triazine (atrazine, propazine and simazine) proposed interim decisions. Upon publication of the Federal Register notice, EPA will take public comments on these documents for 60 days.

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Triazine Cumulative Human Health Risk Assessment

In July 2018 as part of EPA’s registration review process, the Agency released the cumulative human health risk assessment for the triazines. In addition to the cumulative human health risk assessment, the Agency also released atrazine, simazine and propazine human health risk assessments.

In the cumulative assessment, EPA reviewed all available scientific data, including published toxicity and epidemiology literature. EPA’s assessment found no risks of concern when evaluating all dietary exposure sources including drinking water.

The assessment identifies potential risks to:

  • children who crawl and play on lawns treated with atrazine or simazine and
  • workers who mix, load, and apply atrazine

In the December 2019 proposed interim registration review decisions, EPA is proposing mitigation that would address these risks of concern.

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Triazine Ecological Risk Assessments

In 2016, EPA released the draft ecological risk assessments for atrazine, simazine and propazine, which evaluate risks to animals and plants, including amphibians, birds, mammals, fish, reptiles, aquatic invertebrates, aquatic plant communities, and terrestrial plants. For ecological risks, each of the triazines (atrazine, propazine, and simazine) was assessed separately.

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FIFRA Scientific Advisory Panel Meetings on Atrazine

The Agency has consulted with the FIFRA Scientific Advisory Panel on 12 occasions on various topics regarding the evaluation of atrazine data and key aspects of its risk assessments since 2000, all of which are listed in the table below. The SAP is composed of independent scientists who advise on technically challenging scientific assessment issues.

Meeting materials and summaries are available on the FIFRA Scientific Advisory Panel website or in www.regulations.gov (search by the Docket number).

EPA’s FIFRA Scientific Advisory Panel Meetings on Atrazine
Meeting Title Docket Number Date
Problem Formulation for Reassessment of Ecological Risks from Use of Atrazine EPA-HQ-OPP-2012-0230 6/12-15/12
Re-Evaluation of Human Health Effects of Atrazine:  Review of Non-Cancer Effects, Drinking Water Monitoring Frequency, and Cancer Epidemiology EPA-HQ-OPP-2011-0399 7/26-29/11
Re-Evaluation of Human Health Effects of Atrazine:  Review of Non-Cancer Effects and Drinking Water Monitoring Frequency EPA-HQ-OPP-2010-0481 9/14-17/10
Re-Evaluation of Human Health Effects of Atrazine:  Review of Experimental Animal and In Vitro Studies and Drinking Water Monitoring Frequency EPA-HQ-OPP-2010-0125 4/26-29/10
Draft Framework and Case Studies on Atrazine, Human Incidents, and the Agricultural Health Study:  Incorporation of Epidemiology and Human Incident Data into Human Health Risk Assessment EPA-HQ-OPP-2009-0851 2/2-5/10
Presentation of the Atrazine Reevaluation Plan EPA-HQ-OPP-2009-0759 11/3/09
Ecological Significance of Atrazine Effects on Primary Producers in Surface Water Streams in the Corn and Sorghum Growing Region of the United States EPA-HQ-OPP-2009-0104 5/12-15/09
Interpretation of the Ecological Significance of Atrazine Stream-Water Concentrations Using a Statistically-Designed Monitoring Program EPA-HQ-OPP-2007-0934 12/4-7/07
Potential for Atrazine to Affect Amphibian Gonadal Development EPA-HQ-OPP-2007-0498 10/9-12/07
Characterization of Epidemiology Data Related to Prostate Cancer and Exposure to Atrazine EPA-HQ-OPP-2003-0186 7/17-18/03
Potential Developmental Effects of Atrazine on Amphibians EPA-HQ-OPP-2003-0024 6/17-20/03
Issues Pertaining to Atrazine Cancer Risk Assessment Search EPA Archive Not available 6/27-29/00

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