2

Atrazine Preliminary Work Plan – Table of Contents 

Overview 3 

Anticipated Data Needs 4 

Statutory and Regulatory Authority 4 

Chemical Facts 4 

Use and Usage Information 7 

Recent Actions 9 

Anticipated Risk Assessments for Registration Review 9 

Timeline 11 

Next Steps 12 

Appendix – Additional Areas Considered in the Atrazine Registration Review 13 

References:

This Preliminary Work Plan summarizes the Environmental Protection Agency's current position 

based on the following documents: 

1. Addendum to the Problem Formulation for the Ecological Risk Assessment to be 

Conducted for the Registration Review of Atrazine. A. Blankinship. F. Farruggia. James 

Hetrick, PhD. May 14, 2013. Combined in the docket with Meeting of the FIFRA 

Scientific Advisory Panel on the Problem Formulation for the Environmental Fate and 

Ecological Risk Assessment for Atrazine. June 12-15, 2012. 

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

Registration Review. W. Donovan. S. Tadayon. J. Liccione. June 4, 2013. 

3. Atrazine, Propazine and Simazine: Review of Human Incidents. S. Recore. January 22, 

2013 

4. Use Characterization for Atrazine. S. Haddad. B. Phillips. March 22, 2012.

5. Atrazine Screening Level Usage Analysis. November 15, 2011.

6. PRD Label Data Report: Food/Feed & Non-Food/Non-Feed Uses Considered in 

Registration Review Work Planning. February 17, 2012.

These and other supporting documents for the atrazine registration review case may be found in 

the docket EPA-HQ-OPP-2013-0266 at http://www.regulations.gov. 
3

OVERVIEW

The docket for atrazine is now open, initiating the first public comment period for this 

registration review (docket number 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 non-agricultural use sites such as ornamentals, Christmas trees, and sod. 

There are also registered residential and recreational uses on turf such as on parks, golf courses, 

schools, or home lawns and for some commercial and industrial use sites. For human health risk 

assessment, atrazine is part of the triazine common mechanism group based on a common 

toxicity end-point and known mechanism of toxicity. The triazine common mechanism group 

consists of the pesticide active ingredients atrazine, simazine, propazine, and the metabolites 

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

 

This Preliminary Work Plan (PWP) document explains what EPA's Office of Pesticide Programs 

knows about atrazine, highlighting anticipated data and assessment needs, identifying the types 

of information that would be especially useful to the Agency in conducting the review, and 

providing an anticipated timeline for completing the registration review for atrazine. 

 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The Agency intends, by sharing this information in the 

docket, to inform the public of what it knows about atrazine and what types of new data or other 

information would be helpful for the Agency to receive as it moves toward a decision on 

atrazine. The Agency encourages all interested stakeholders to review the PWP and Appendix 

and to provide comments and additional information that will help the Agency’s decisionmaking process for atrazine. In addition to general areas on which persons may wish to 

comment, there are some areas identified in the PWP and Appendix about which the Agency 

specifically seeks comments and information. Interested stakeholders could include: 

environmental non-profit or interest groups; pesticide manufacturers; agricultural labor or 

commodity groups; commercial, institutional, residential, and other users of pesticides; or the 

public at large. 

The Preliminary Work Plan begins by discussing that there are no anticipated data needs for 

atrazine. Next, it discusses the statutory and regulatory authority for Registration Review. Then 

the document provides chemical facts, use and usage information, recent actions, anticipated risk 

assessments, and projected registration review timeline for atrazine. Finally, the Appendix 

includes identification and discussion of some areas that are generally considered in Registration 

Review along with some additional chemical case-specific information. 

 

 

1

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

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

Risk Assessment. J. Morales. March 28, 2006.) 
4

ANTICIPATED DATA NEEDS

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

by the Agency. There are no remaining data gaps anticipated for the registration review of 

atrazine. For further discussion of existing atrazine data, see the Addendum to the Problem 

Formulation for the 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.

STATUTORY AND REGULATORY AUTHORITY

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that 

they will not cause unreasonable risks to human health or the environment when used as directed 

on product labeling. 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 of no unreasonable adverse effects to human health or the 

environment. Changes in science, public policy, and pesticide use practices will occur over time. 

Through the registration review program, the Agency periodically reevaluates pesticides to make 

sure that as change occurs, products in the marketplace can be used safely. Information on this 

program is provided on EPA’s website.2

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. The regulations governing registration review begin at 40 CFR 155.40. The 

Agency will consider benefits information and data as required by FIFRA. The public phase of 

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

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop a Final Work Plan (FWP) and anticipated schedule for 

the registration review of atrazine. 

CHEMICAL FACTS

Table 1 provides a summary of the chemical facts for atrazine. 

Table 1: Chemical Facts for Atrazine

PC code 080803 

Case Number 0062 

CAS Number 1912-24-9 

Year first registered 1958 

 

2

 http://www.epa.gov/oppsrrd1/registration_review/ 
5

Table 1: Chemical Facts for Atrazine

Pesticide Type Selective herbicide 

Chemical class Triazine 

Reregistration Eligibility 

Decision (RED) 

January 2003 and October 2003 Interim REDs; RED finalized April 

6, 2006 upon completion of triazine cumulative risk assessment. 

Tolerance Reassessment 

Eligibility Decision 

(TRED) 

Not applicable because tolerances were reassessed as part of the 

RED. 

Cumulative group Triazine. The most recent human health cumulative risk 

assessment was completed in March 2006. (Triazine Cumulative 

Risk Assessment. J. Morales. March 28, 2006.) 

40 CFR Citation Tolerances for atrazine are established in 40 CFR § 180.220. 

Dual-use Atrazine is registered for conventional pesticidal uses only and has 

no registered antimicrobial or biopesticidal uses. 

Non-pesticidal uses There are no identified non-pesticidal uses of atrazine. 

Pesticide Re-evaluation 

Division, Chemical 

Review Manager 

Monica Wait, wait.monica@epa.gov, (703)347-8019 

Registration Division, 

Product Manager 

Kable Davis, davis.kable@epa.gov, (703)306-0415 

Table 2 below provides references to atrazine public dockets and FIFRA Science Advisory Panel 

(SAP) meetings that have occurred in recent years and may be of interest to some stakeholders. 

Meeting summaries, supporting documents, appendices, public comments, and technical papers 

about atrazine-specific scientific issues may be found in these dockets. 

Table 2: Atrazine Existing Public Dockets and Recent SAP Meetings 

Docket # at 

regulations.gov Docket Title and/or SAP Title Notes 

EPA-HQ-OPP-2003-

0367 

Atrazine Interim Reregistration 

Eligibility Decision (IRED) 

Includes January and October 

2003 Atrazine IREDs, 

support documents, data 

evaluation records (DERs), 

atrazine water monitoring 

data submitted by the 

registrants from 2003 to 

2012, and more. 

See document EPA-HQOPP-2003-0367-0207 for a 

bibliography of the aquatic 

plant community microcosm 

and mesocosm study DERs 

contained in this docket. 
6

Table 2: Atrazine Existing Public Dockets and Recent SAP Meetings 

Docket # at 

regulations.gov Docket Title and/or SAP Title Notes 

EPA-HQ-OPP-2004-

0319 

Atrazine Special Review Includes documents related 

to EPA’s Special Review 

process for atrazine, initiated 

in 1994. 

EPA-HQ-OPP-2005-

0481 

Triazine Cumulative Risk Assessment Includes March 2006 human 

health cumulative risk 

assessment and supporting 

documents. 

EPA-HQ-OPP-2007-

0498 

Potential for Atrazine to Affect 

Amphibian Gonadal Development 

SAP meeting held from 

10/9/07 to 10/12/07 

EPA-HQ-OPP-2007-

0934 

Interpretation of the Ecological 

Significance of Atrazine Stream-Water 

Concentrations Using a StatisticallyDesigned Monitoring Program 

SAP meeting held from 

12/4/07 to 12/7/07 

EPA-HQ-OPP-2009-

0104 

Ecological Significance of Atrazine 

Effects on Primary Producers in 

Surface Water Streams in the Corn and 

Sorghum Growing Region of the 

United States 

SAP meeting held from 

5/12/09 to 5/15/09 

EPA-HQ-OPP-2009-

0759 

Presentation of the Atrazine 

Reevaluation Plan 

SAP meeting held 11/3/09 

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 

SAP meeting held from 

2/2/10 to 2/5/10 

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 

SAP meeting held from 

4/26/10 to 4/29/10 

EPA-HQ-OPP-2010-

0481 

Re-Evaluation of Human Health 

Effects of Atrazine: Review of NonCancer Effects and Drinking Water 

Monitoring Frequency 

SAP meeting held from 

9/14/10 to 9/17/10 

EPA-HQ-OPP-2011-

0399 

Re-Evaluation of Human Health 

Effects of Atrazine: Review of NonCancer Effects, Drinking Water 

Monitoring Frequency, and Cancer 

Epidemiology 

SAP meeting held from 

7/26/11 to 7/29/11 

EPA-HQ-OPP-2011-

0586 

Petition Requesting Ban on Use and 

Production of Atrazine 

Petition submitted in May 

2011 by Save the Frogs 
7

Table 2: Atrazine Existing Public Dockets and Recent SAP Meetings 

Docket # at 

regulations.gov Docket Title and/or SAP Title Notes 

EPA-HQ-OPP-2012-

0230 

Problem Formulation for Reassessment 

of Ecological Risks from Use of 

Atrazine 

SAP meeting held from 

6/12/12 to 6/15/12 

EPA-HQ-OPP-2013-

0266 

Atrazine Registration Review Docket opened June 2013 

USE AND USAGE INFORMATION

Table 3 summarizes the use and usage information for atrazine. Please see Use Characterization 

for Atrazine in the registration review docket for more details. 

Table 3: Atrazine Use and Usage Information

Summary of Use Atrazine is a triazine herbicide registered for use against broadleaf 

and some grassy weeds in a variety of agricultural and nonagricultural use sites. 

Use Sites Agricultural: Registered for use on corn, sweet corn, sorghum, 

sugarcane, wheat (wheat stubble on fallow land), macadamia nuts, 

guava, and range grasses.3

Non-agricultural: Registered for use in conifer forests, Christmas 

tree farms, sod farms, ornamental grasses, ornamental plants, 

ornamental turf, outdoor residential lawn (this use is primarily in 

Florida and the Southeast), schools, parks, playgrounds, and athletic 

fields. Atrazine is also registered for use on roadsides, rights-ofway, airfields, vacant lots, lumber yards, agricultural buildings, 

industrial sites, and storage sites. 

Summary of Usage Agricultural usage: Based on survey data from 2000 to 2010, 

annual usage averaged approximately 72 million pounds of active 

ingredient (a.i.) for 71 million acres. For the time period from 2006 

to 2010, usage averaged approximately 66 million pounds a.i. for 

67 million acres. From 2006 to 2010, the primary crops in terms of 

average annual pounds of a.i. applied were corn (88%), sorghum 

(8%), and sugarcane (2%). 

Non-agricultural usage: Available non-agricultural usage data is 

limited to certain types of applications and does not include usage 

information for all non-agricultural use sites. In 2006, 1.2 million 

pounds a.i. was applied by professional applicators to golf courses, 

 

3

 The March 22, 2012 Use Characterization for Atrazine erroneously includes oats as a registered use site. Atrazine 

is not registered for use on oats. Additionally, that document lists soybeans as a use site. Soybeans is registered as 

a Special Local Needs (Section 24c) use site in Kansas only. There are no Section 3 registrations for use of 

atrazine on soybeans. 
8

Table 3: Atrazine Use and Usage Information

institutional turf, landscape, lawns, turf farms, and in nurseries or 

greenhouses. For the consumer market, approximately 400,000 

pounds a.i. were applied in 2005 as a lawn herbicide. 

Formulation Type(s) Granular, wettable powder, water dispersible granules, emulsifiable 

concentrate, flowable concentrate, soluble concentrate, ready-touse, and water soluble packs. 

Some products are co-formulated with other herbicides and/or 

fertilizers. 

Application Method(s) Groundboom sprayer, aircraft, tractor-drawn spreader, rights-ofway sprayer, low pressure handwand, backpack sprayer, lawn 

handgun, push-type spreader, and hand-crank spreader. 

Technical Registrant(s) Syngenta Crop Protection, Agan Chem Mfg Ltd, Drexel Chemical 

Company, Oxon Italia SPA 

Registrations Approximately 160 Section 3 registrations4 and 30 Section 24(c) 

(special local needs) registrations 

Restricted Use Products containing > 4% atrazine (75% of registrations) are 

classified as restricted use which must be applied by certified 

applicators only. Products containing ≤ 4% atrazine are not 

classified as restricted use and are registered for lawn applications. 

Guidance for Commenters: Additional areas of use and usage related information

requested for this registration review, and of particular interest to EPA, are described below. 

 Confirmation of the following label information for all agricultural and non-agricultural 

uses: sites of application; formulations; application methods and equipment; maximum 

application rates; total seasonal/calendar year maximum rates; frequency of application, 

application intervals, and maximum number of applications per season or calendar year; 

and geographic limitations and/or prohibitions on use. 

 Use distribution (e.g., acreage and geographical distribution of relevant use sites). 

 Median and 90th percentile reported use rates (lbs ai/A) from usage data – national, state, 

and county. 

 Typical application timing (date of first application) – national, state, and county (e.g. 

prior to planting, at planting, preemergence, postemergence, fall). 

 Typical application interval (days). 

 State or local use restrictions. 

 Foreign technical registrants not listed above who supply technical atrazine to the US 

market. 

 

4

 Section 3 product labels can be obtained from the Pesticide Product Label System (PPLS) website 

(http://oaspub.epa.gov/pestlabl/ppls.home). 
9

RECENT ACTIONS

As noted earlier in Table 2, there have been several SAPs in the past few years for atrazine as the 

state of the science has continued to evolve and new data have become available. The SAPs 

have addressed issues concerning human health, such as incident and epidemiology data, cancer 

effects, and drinking water monitoring, as well as ecological issues such as effects on 

amphibians, aquatic ecosystems, and monitoring of atrazine in streams. For the list of recent 

SAPs and their associated docket numbers, see Table 2. Additional details and supporting 

documents can be found in the individual SAP dockets. 

The January and October 2003 Atrazine IREDs, May 2004 Memorandum of Agreement (MOA) 

with the atrazine registrants5, and reregistration data call-ins (GDCI-080803-20871 and GDCI080803-25114) involve requirements for submission of annual water monitoring data for raw and 

finished drinking water sources under provisions of the Atrazine Monitoring Program (AMP) 

and ecological water monitoring data for smaller streams and watersheds under the Atrazine 

Ecological Exposure Monitoring Program (AEEMP6

). The raw monitoring data files are 

publicly available in the atrazine IRED docket (see Table 2) and on EPA’s Atrazine Updates 

webpage.7 As new data become available, EPA conducts reviews of the registrant submitted 

water monitoring data and other water monitoring programs looking for atrazine, such as 

USGS’s National Water Quality Assessment Program (NAWQA) and state monitoring 

programs. 

The Agency is currently evaluating a tolerance petition for simazine (2F8006, 77 FR 50686) to 

establish crop group tolerances for stone fruit, pome fruit, citrus fruit, and tree nuts; to remove 

individual tolerances which would be replaced by the new crop groups; and for several other 

related actions. EPA is in the process of reviewing this request which will likely necessitate an 

updated assessment for the triazine cumulative group. 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for the single active ingredient 

atrazine was completed on April 16, 2002 in preparation for the IRED. The most recent human 

health triazine cumulative risk assessment was completed on March 28, 2006. The most recent 

comprehensive ecological and environmental fate risk assessment was completed on April 22, 

2002 for the IRED. Findings and conclusions from these risk assessments are summarized in the 

Addendum to the Problem Formulation for the 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. 

During registration review, the Agency anticipates the need to conduct a comprehensive 

ecological risk assessment, including an endangered species assessment, for all uses of atrazine. 

For human health, EPA anticipates the need to conduct revised dietary, residential, occupational, 

and cumulative risk assessments during registration review. If toxicological endpoints or points 

 

5

 http://www.epa.gov/oppsrrd1/reregistration/atrazine/AtrazineMOA.pdf 6

 This program is also referred to as the Atrazine Ecological Monitoring Program (AEMP) in some documents. 7

 http://www.epa.gov/oppsrrd1/reregistration/atrazine/atrazine_update.htm 
10

of departure are revised based on additional data available in the open literature, they will be 

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

or default exposure assumptions. 

Table 4 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and HED Scoping Document. 

Table 4: Anticipated 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 June 2012 

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 is 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 

Other 

Aggregate Y Evaluates the combined risk from dietary and 

residential exposures. 

Cumulative Y An assessment of the triazine 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. 
11

Guidance for Commenters: Additional ecological information requested for this 

registration review, and of particular interest to EPA, is described below. 

 The May 14, 2013 Problem Formulation Addendum has several “Stakeholder Input 

Requests” for additional information: 

o Page 8 – EPA is interested in any information regarding what may constitute 

‘normal development’ for different amphibian species under different 

environmental conditions. This information can be used to evaluate if 

environmental conditions described in the open literature studies were appropriate 

for proper development of different species. 

o Page 11 – EPA is interested in receiving feedback from stakeholders on our 

proposed approach for evaluating the amphibian toxicity data and is soliciting 

alternative scientifically sound approaches for evaluating the large set of toxicity 

data available for amphibians. 

o Page 13 – EPA is interested in receiving information related to potential 

differences in sensitivities with regard to biological and/or physiological factors 

between Xenopus laevis and native North American (e.g., Rana pipiens) species 

of frogs. EPA is interested in understanding if there are fundamental 

toxicodynamics and/or toxicokinetic differences between X. laevis and other 

native species of frogs such that it is expected to result in a markedly different 

response to a chemical such as atrazine. 

 Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency. 

 Water quality monitoring data (see Appendix for further details). 

TIMELINE

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

review in Table 5 below. 

Table 5: Projected Atrazine Registration Review Timeline

Activities Estimated Date

Opening the Docket 

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

Close Public Comment 2013 – August 

Case Development 

Final Work Plan 2013 – November 

60-day Public Comment Period for Draft Risk Assessments8,9 2015 – April - June 

Registration Review Decision 

 

8

 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. 

9

 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 for draft risk assessments. 
12

Table 5: Projected Atrazine Registration Review Timeline

Activities Estimated Date

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

After the 60-day public comment period closes, the Agency will review and respond to any 

comments received in a timely manner and then issue a Final Work Plan for the registration 

review of atrazine. 

 
13

Appendix – Additional Areas Considered in the Atrazine Registration Review

PUBLIC COMMENTS AND FEEDBACK:

Guidance for Commenters: The areas below highlight topics of special interest to the Agency 

where your comments, data submissions, or reference to sources of additional information could 

be of particular use.

Trade Irritants: 

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The Agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Growers and other stakeholders are asked to 

comment on any trade irritant issues resulting from lack of MRLs or disparities between U.S. 

tolerances and MRLs in key export markets, providing as much specificity as possible regarding 

the nature of the concern. 

Water Quality: 

As discussed on page 20 of the June 2012 Problem Formulation, atrazine is mobile and persistent 

in the environment. The main routes of dissipation are microbial degradation under aerobic 

conditions, runoff, and leaching. Because of its persistence and mobility, atrazine will move into 

surface and groundwater, which has been confirmed by the widespread detections in monitoring 

data. Additional information about the environmental fate of atrazine can be found in the June 

2012 Problem Formulation. As was discussed previously in this PWP, EPA is actively 

collecting, analyzing, and staying abreast of water quality monitoring data for atrazine collected 

through the AMP and AEEMP programs and other monitoring programs looking for atrazine, 

such as NAWQA and state monitoring programs. 

Atrazine is identified as a cause of impairment, as defined under section 303(d) of the Clean 

Water Act, for 173 water bodies in Iowa, Illinois, Kansas, Missouri, Nebraska, and Ohio, based 

on information provided at EPA’s website.10 In addition, Total Maximum Daily Loads (TMDL) 

have been developed for atrazine in 68 impaired water bodies in Alabama, Iowa, Illinois, Kansas, 

Missouri, Nebraska, Ohio, and Texas, based on information provided at the website.11 More 

information on impaired water bodies and TMDLs can be found at EPA’s website.12 

The Agency invites submission of water quality data for atrazine. To the extent possible, 

data should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process13 in order to ensure that it can be 

used quantitatively or qualitatively in pesticide risk assessments. 

 

10 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 11http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES

12 http://www.epa.gov/owow/tmdl/ 13 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
14

Environmental Justice: 

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to atrazine compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population.

ENDANGERED SPECIES:

A risk assessment that supports a complete endangered species determination has not been 

conducted for atrazine. The ecological risk assessment planned during registration review will 

allow the Agency to determine whether use of atrazine has “no effect” or “may affect” federally 

listed threatened or endangered species (listed species) or their designated critical habitats. 

When an assessment concludes that a pesticide’s use “may affect” a listed species or its 

designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service 

and/or National Marine Fisheries Service (the Services), as appropriate. 

ENDOCRINE DISRUPTOR SCREENING PROGRAM:

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of the reregistration decision for atrazine, EPA reviewed these data 

and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing 

hazard database. However, as required by FFDCA section 408(p), atrazine is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 
15

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and 9 inert ingredients. Atrazine was included on 

that list and has been issued an order to conduct the Tier 1 testing. Once all required Tier 1 and 

Tier 2 data have been received and reviewed, the endpoints and safety factors used for risk 

assessment purposes will be examined and a new risk assessment performed if necessary. For 

further information on the status of the EDSP, the policies and procedures, the list of 67 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.14

HUMAN STUDIES:

Occupational and Residential 

Past atrazine risk assessments rely in part on data from studies in which adult human subjects 

were intentionally exposed to a pesticide to determine their dermal and inhalation exposure. 

Many such studies, involving exposure to many different pesticides, comprise generic pesticide 

exposure databases such as the Pesticide Handlers Exposure Database (PHED), the Agricultural 

Reentry Task Force (ARTF) Database, and the Outdoor Residential Exposure Task Force 

(ORETF) Database. EPA has reviewed all the studies supporting these multi-pesticide generic 

exposure databases, and has found no clear and convincing evidence that the conduct of any of 

them was either fundamentally unethical or significantly deficient relative to the ethical 

standards prevailing at the time the research was conducted. All applicable requirements of 

EPA’s Rule for the Protection of Human Subjects of Research (40 CFR Part 26) have been 

satisfied, and there is no regulatory barrier to continued reliance on these studies. 

AGRICULTURAL HEALTH STUDY:

Atrazine is among several agricultural chemicals included in the Agricultural Health Study 

(AHS). The AHS began in 1993 and is a collaboration of the National Institute of 

Environmental Health Sciences (NIEHS), the National Cancer Institute (NCI), the EPA, and the 

National Institute for Occupational Safety and Health (NIOSH). Designed as a large long-term 

epidemiological study, the AHS collects and analyzes data on the health and work practices of 

nearly 90,000 farmers and their families in Iowa and North Carolina who enrolled in the study 

before any disease developed. The study focuses particularly on farmers' exposure to 50 

chemicals including many of the most widely used pesticides. As data are collected over a 

period of years, scientists can compare overall health outcomes for people who differ in whether 

they have had exposure to various chemicals. While these comparisons cannot conclusively 

demonstrate how exposure affects health, they can show some statistical associations. More 

information on the AHS can be found at: http://aghealth.nci.nih.gov. EPA is monitoring the 

results of the AHS and will consider this study in the registration review of atrazine as 

appropriate. 

 

14 http://www.epa.gov/endo/