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INTRODUCTION

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for 

the registration review of atrazine. This work plan addresses public comments received 

concerning the Preliminary Work Plan (PWP), which was posted in the atrazine registration 

review docket (EPA-HQ-OPP-2013-0266). Atrazine is a triazine herbicide registered for use on 

various agricultural crops with the largest use on corn, sorghum, and sugarcane. Additionally, it 

is registered for use on wheat, guava, macadamia nuts, and range grasses and for several nonagricultural use sites such as ornamentals, Christmas trees, and sod. There are also registered 

residential and recreational uses on turf such as on parks, gold courses, schools, or home lawns 

and for some commercial and industrial use sites. For human health risk assessment, atrazine is 

part of the trazine common mechanism group based on a common toxicity end-point and known 

mechanism of toxicity. The trazine common mechanism group consists of the pesticide active 

ingredients of atrazine, simazine, propazine, and the metabolites desethyl-s-atrazine (DEA), 

desisopropyl-s-atrazine (DIA), and diaminochlorotriazine (DACT).1

 

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. Changes in science, public policy, and pesticide use practices occur over time. The 

registration review program is intended to make sure that, as the ability to assess risk evolves and 

as policies and practices change, all registered pesticides continue to meet the statutory standard. 

The public phase of registration review begins when the initial docket is opened for each case. 

Information on this program is provided on the Agency’s website.

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The FWP begins with any updates since the PWP was issued. Next is a summary of substantive 

comments received during the public comment period for the PWP concerning anticipated data 

needs, expected risk assessments, or the estimated timeline identified in the PWP, and a 

summary of the Agency’s responses to those comments. This section is followed by registration 

review risk assessments expected to be conducted, and the projected registration review timeline

for atrazine. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

On July 25, 2013, EPA held a focus meeting with the atrazine technical registrants (Syngenta

Crop Protection LLC, Drexel Chemical Company, Agan Chem. Mfg. Ltd., and Oxon Italia

S.P.A.). Topics discussed during the meeting included: the timeline for the registration review of 

atrazine; clarifying labeled agricultural and non-agricultural use sites; atrazine usage on some 

non-agricultural sites such as forestry, turf, fallow, conservation reserve program; label 

uncertainties that could lead to conservative assumptions in the registration review preliminary 

risk assessments; existing stewardship programs in several vulnerable watersheds; and voluntary 

atrazine data the registrants expect to submit for registration review. More information on the 

atrazine focus meeting can be found in the Atrazine Registration Review Focus Meeting 

 1 There are other trazine pesticides, such as ametryn, prometryn, and prometon, but they are excluded from the 

trazine common mechanism group because they do not share the same toxicity profile. (Triazine Cumulative Risk 

Assessment. J. Morales. March 28, 2006.) 2 http://www.epa.gov/oppsrrd1/registration_review/
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Summary, available in the atrazine registration review docket, EPA-HQ-OPP-2013-0266, at 

www.regulations.gov.

On October 31, 2013, EPA met with Syngenta to discuss the Atrazine Ecological Exposure 

Monitoring Program (AEEMP). This water monitoring program of small streams in vulnerable 

watersheds was required by the 2003 Interim Reregistration Eligibility Decision (IRED) for 

Atrazine and subsequent Memorandum of Agreement. More information on the AEEMP can be 

found in the Atrazine (IRED) docket, EPA-HQ-OPP-2003-0367.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on the Atrazine Preliminary Work Plan, which opened 

on June 26, 2013, and closed on August 26, 2013, the Agency received over 55,000 public 

comments opposing and supporting the continued registration of atrazine. These comments were 

submitted by individual citizens, a registrant (Syngenta), trade organizations (grower and 

industry groups), the Federal Endangered Species Task Force (FESTF), not-for-profit 

organizations, and a state representative. The comments do not address the timeline described in 

the PWP or the planned ecological and human health risk assessments. In the PWP, EPA also 

solicited comments on the specific topics of environmental justice, water quality concerns, and 

trade irritants, no comments or information were received on environmental justice or trade 

irritants. Comments on water quality concerns were received and will be considered as part of 

the formulation of the atrazine preliminary risk assessments. In addition, the drinking water 

assessment will incorporate atrazine water monitoring data.

Comments from the following groups represent a large number of comments received which

oppose the continued use of atrazine: Center for Biological Diversity (42,481 signatories); 

Pesticide Action Network (6,674 signatories and 5,609 signatories in two submissions); Save the 

Frogs (104 signatories); Beyond Pesticides; Frog Safe, Inc.; and concerned citizens. 

The EPA has generally grouped the contents of these comments into concerns for the following 

areas:

• Ecotoxicity of atrazine to aquatic and terrestrial organisms

• Concentrations of atrazine in surface and drinking water

• Potentially underestimated endocrine effects and carcinogenicity 

Comments from the following groups support the continued use of atrazine: South Dakota 

Corn Growers Association; Chemical Industry Council of Illinois; Iowa Farm Bureau 

Federation; Illinois Farm Bureau; Maryland Grain Producers Association; Missouri Corn 

Growers Association; American Farm Bureau Federation; Kansas Grain Sorghum Producers 

Association; Kansas Corn Growers Association; Kentucky Corn and Small Grain Growers 

Associations; Hawaii Agriculture Research Center; National Farmers Union; Texas Seed Trade 

Association; Illinois Corn Growers Association; Ohio Corn and Wheat Growers Association;

Nebraska Corn Growers Association; Illinois Soybean Association; Michigan Farm Bureau; 

National Corn Growers Association; Oregonians for Food and Shelter; Oregon Farm Bureau; 

National Corn Growers Association; HC&S Sugarcane Plantation; and industry groups (Triazine 

Network) Ohio State Representative Andy Thompson (95th District), and individual growers. 

The EPA has generally grouped the contents of these comments into support for the following areas:
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• Cost-effective, broadleaf weed control at lower application rates

• Increased crop yield 

• Control for herbicide resistant weeds and limited available alternatives

Syngenta, the Center for Biological Diversity, and the Center for Regulatory Effectiveness also 

submitted comments regarding the planned endangered species assessment, which are addressed 

in the Environmental Fate and Effects Division’s Response to Public Comments on the 

Registration Review Preliminary Problem Formulation for Atrazine. FESTF commented that 

Syngenta is a member of FESTF and is entitled to rely on FESTF data to help address species 

proximity to atrazine use sites for the planned endangered species assessment.

Public comments and EPA responses in their entirety are located in the docket, EPA-HQ-OPP2013-0266. Summarized public comments and Agency responses related to the anticipated 

ecological risk assessment or data needs are in the Environmental Fate and Effects Division’s 

Response to Public Comments on the Registration Review Preliminary Problem Formulation for 

Atrazine, while those relevant to the anticipated human health risk assessment or data needs are 

in the Atrazine. Response to Comments on the Human Health Risk Scoping Document in Support 

of Registration Review. Comments and responses on atrazine use and usage information 

described in the PWP and BEAD Chemical Profile (BCP) are in the BEAD Response to Atrazine 

Public Comments.

This section does not capture every comment made about the PWP nor all of the Agency’s 

responses. Summarized below are public comments not addressed in the Agency’s response to 

comments documents and/or are of a broader regulatory nature. No comments resulted in 

changes to the risk assessments, data needs, or time frame of registration review activities. 

Comments submitted by Syngenta in EPA-HQ-OPP-2013-0266-0299.

1. Comment: Syngenta is coordinating with other atrazine technical registrants to develop a 

comprehensive use table for all atrazine products and formulation types. The table will 

include various use clarifications discussed in the July 2013 Atrazine Focus Meeting as well 

as address several discrepancies in the use and usage information listed in the PWP and the 

Atrazine Label Data Report: Food/Feed & Non-Feed uses Considered in Registration 

Review Work Planning.

Response: EPA would appreciate this detailed and comprehensive use information to be 

submitted as soon as possible and will consider this information prior to conducting the 

human health and ecological preliminary risk assessments for registration review.

Comments submitted by Center for Regulatory Effectiveness (CRE) in EPA-HQ-OPP2013-0266-0076.

2. Comment: CRE stated that the registration review of atrazine should include documentation 

of the Agency’s compliance with EPA’s Information Quality Act (IQA) Guidelines and EPA’s 

Council for Regulatory Environmental Models (CREM) Guidance. Additionally, CRE 

expressed concerns regarding the reproducibility of data from peer-reviewed journal 

articles. CRE requested that EPA ensure that any data relied on for risk assessments or 
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Endangered Species Act (ESA) consultations as part of the registration review of atrazine 

meet IQA reproducibility guidelines. 

Response: EPA considers numerous sources for information during registration review, 

including open literature and public comment submissions. All open literature studies 

considered are reviewed consistent with EPA Office of Pesticide Program’s (OPP) publically 

available guidance for identifying, selecting, and evaluating open literature studies to ensure 

transparency and consistency.

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 The principles articulated in these guidance documents are 

consistent with the Agency’s policy and procedural guidance for ensuring and maximizing 

the quality of information as stated in EPA 2002 - Guidelines for Ensuring and Maximizing 

the Quality, Objectivity, Utility, and Integrity of Information Disseminated by the 

Environmental Protection Agency and the Agency Risk Characterization Policy, which 

describes a philosophy of transparency, clarity, consistency, and reasonableness.

Additionally, models and standard operating procedures used in risk assessment formulation 

are reviewed by the FIFRA Scientific Advisory Panel (SAP), which is composed of 

biologists, statisticians, toxicologists and other experts who provide independent scientific 

advice to the EPA on a wide-range of health and safety issues related to pesticides. 

Comments submitted by Environmental Law and Policy Center (ELPC) in EPA-HQ-OPP2013-0266-0301.

3. Comment: The ELPC moved to unseal numerous documents filed under seal in City of 

Greenville, Illinois, et. Al. v. Syngenta Crop Protection, LLC et. Al (S.D. Ill. Case No. 10-cv188), and requested to the opportunity to submit to EPA any documents related to public 

health effects of atrazine use if and when they become available after the atrazine PWP 

public comment period closes. Additionally, the ELPC noted concerns regarding the 

impartiality and comprehensiveness of information Syngenta has submitted to EPA.

Response: The Agency appreciates ELPC’s notification of potential documents that could 

provide EPA with additional information on atrazine. The Agency has planned two 

additional comment periods during the registration review of atrazine. The next comment 

period is anticipated to begin in April 2015 in conjunction with the publication of atrazine 

preliminary risk assessments. EPA encourages the ELPC to provide any new information at 

that time. Regarding the ELPC’s concern on the impartiality of Syngenta’s submissions, 

EPA intends to conduct a thorough review of data submitted from all sources before 

including it in preliminary risk assessments. Data review is conducted based on the 

abovementioned guidance documents for open literature as well as Office of Chemical Safety 

and Pollution Prevention (OSCPP) harmonized test guidelines.

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PLANNED DATA NEEDS

As indicated in the PWP, there are no planned data needs for the registration review of atrazine. 

An extensive amount of atrazine toxicity and effects data have been submitted to and reviewed 

by the Agency. No public comments resulted in changes to the lack of data needs. For further 

discussion of existing atrazine data, see Addendum to the Problem Formulation for the 

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OPP guidance for identifying, selecting, and evaluating open literature studies is available at: 

http://www.epa.gov/pesticides/science/literature-studies.html#eval 4 OSCPP test guidelines are available at: http://www.epa.gov/ocspp/pubs/frs/home/guidelin.htm
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Ecological Risk Assessment to be Conducted for the Registration Review of Atrazine and 

Atrazine, Propazine, and Simazine. Human Health Risk Scoping Document in Support of 

Registration Review. 

RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency will conduct a comprehensive ecological risk assessment, 

including an endangered species assessment, for all uses of atrazine. For human health, EPA 

will conduct revised dietary, residential, occupational, and cumulative risk assessments during

registration review. If toxicological endpoints or points of departure are revised, they will be 

considered in the new assessments, as well as any changes to the standard operating procedures 

or default exposure assumptions.

Table 2 below summarizes the planned registration review risk assessments based on the EFED 

Problem Formulation and HED Scoping Document a and the planned assessments have not 

changed from what was included in the PWP.

Table 2: Planned Risk Assessments for the Atrazine Registration Review

Type of Risk Assessment Conduct? Notes

Ecological and Environmental Fate

Comprehensive ecological 

(species to be assessed include 

terrestrial and aquatic 

organisms), including 

endangered species 

Y The parent atrazine will be considered the stressor of 

concern because it is expected to be protective for 

any non-target organisms that may be exposed to the 

parent and any of its degradates. 

Incidents Will check for 

updates

A search of the ecological incident databases will be 

conducted and analyzed for the upcoming 

registration review risk assessment. See page 93 of 

the Problem Formulation for additional details. 

Human Health

Dietary

Food Y

Drinking water Y The drinking water assessment will incorporate 

atrazine water monitoring data. 

Occupational

Handlers (mixers, loaders, 

applicators)

Y As discussed further in the Scoping Document, the 

durations of exposure are expected to be short- and 

intermediate-term. Long-term exposures are not 

anticipated. 

Post-application Y

Residential

Handlers Y As discussed further in the Scoping Document, the 

duration of exposure are expected to be 

short-term only. Intermediate- and long-term 

exposures are not anticipated based on the residential 

use patterns of atrazine. 

Post-application Y
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Table 2: Planned Risk Assessments for the Atrazine Registration Review

Type of Risk Assessment Type of Risk 

Assessment Type of Risk Assessment

Other

Aggregate Y Evaluates the combined risk from dietary and 

residential exposures.

Cumulative Y An assessment of the trazine cumulative group is 

expected as part of registration review.

Tolerances Y Tolerances for atrazine will be assessed and revised, 

as needed, during registration review.

Incidents Will check for 

updates

For a discussion of reported human incidents for 

atrazine, see the Atrazine, Propazine, and Simazine: 

Review of Human Incidents.

TIMELINE

EPA has created the following estimated timeline for the completion of the atrazine registration

review in Table 3 below. The projected timeline has not changed since the PWP. 

Table 3: Registration Review for Atrazine– Projected Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period June 2013 – Completed

Close Public Comment August 2013 – Completed

Case Development

Final Work Plan December 2013– Completed

60-day Public Comment Period for Draft Risk Assessments5,6 2015– April -June

Registration Review Decision

60-day Public Comment Period for Proposed Registration Review 

Decision

2015– Oct. – Dec.

Registration Review Decision and Begin Post-Decision Follow-up 2016

Total (years) 3

NEXT STEPS

As noted previously, the Agency will conduct comprehensive ecological and human health risk 

assessments during registration review, which are anticipated to be available for public comment 

between April – June 2015.

 5 The regulations governing Registration Review generally require the Agency to provide a public comment period 

of at least 30 calendar days for draft risk assessments; see 40 CFR Part 155.53(c). For conventional pesticides, the 

Agency plans to provide a 60 calendar day public comment period generally for draft risk assessments. 6 The registration review schedule for most conventional pesticides includes a 6 month period after the Final Work 

Plan to issue a data call-in and then an appropriate time period for the required data to be submitted to EPA. 

However, because there are no anticipated human health or environmental fate and effects data needs for the 

atrazine registration review, the schedule has been modified as appropriate.