Docket Number EPA-HQ-OPP-2014-0224 

www.regulations.gov 

Imazaquin Final Work Plan 

Registration Review 

Case Number 7204 

March 2015 

Approved by: ~P ~.::p 

Date: 

Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

.3) 9 jcflOI~ 
INTRODUCTION 

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

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

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

review docket (EPA-HQ-OPP-2014-0224). Unless otherwise specified, references to imazaquin 

throughout this document include imazaquin and its ammonium salt. Imazaquin is an 

imidazolinone herbicide that is formulated as an acid or ammonium salt. It is registered for uses 

as a pre-plant, pre-emergence and early post-emergence on soybeans. It is also registered for preand post-emergence weed control on ornamentals and warm season turfgrass in both residential 

(lawns) and non-residential (golf-courses) settings. 

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. 1 

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 planned data needs, risk assessments expected to be conducted, and the projected 

registration review timeline for imazaquin. Lastly, there is a discussion of next steps. 

UPDATES SINCE THE PWP WAS ISSUED 

The Agency approved a process for implementing the new pollinator data requests consistent 

with OPP's 2014 Guidance for Assessing Pesticide Risks to Bees2

. The planned data needs for 

imazaquin include the current bee-related data requirements that are included in 40 CFR Part 158 

and additional studies which are consistent with the new Guidance for Assessing Pesticide Risks 

to Bees (see Table 1 for the new pollinator data requirements). 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

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

opened on September 24, 2014 and closed on November 24, 2014, the Agency received three 

public comments. Comments were submitted by the Center for Biological Diversity (CBD), 

FIFRA Endangered Special Task Force (FESTF), and from Project Apis m. (PAm). 

1 http://www .epa.gov/oppsrrd l/registration _review/ 2 

http://www.epa.gov/pesticides/science/efed/policy guidance/team authors/terrestrial biology tech team/Guidance 

AssessingPesticidesRisk2Bees.pdf. 

2 
The comments from CBD focused on the EPA's duty to consult with the U.S. Fish and Wildlife 

Service and the National Marine Service (the Services) on the registration review of imazaquin 

in accordance with the Endangered Species Act (ESA). The comment from FESTF identified 

BASF Corporation as a FESTF member, which is entitled to rely on FESTF data. Project Apis 

m. (PAm) is a non-profit honey bee research funding organization in the U.S. Their comments 

focused on the development of a federal strategy to protect honey bees and other pollinators, and 

their willingness to assist with, coordinate, or manage new federal initiatives. These public 

comments are located in the docket, EPA-HQ-OPP-2014-0224. 

The comments do not address the timeline described in the PWP, or the planned ecological and 

human health risk assessments and data requirements. In the PWP, EPA also solicited comments 

on the specific topics of environmental justice, water quality concerns, and trade irritants, but no 

comments or information were received on those issues. 

Comments submitted by FESTF in EPA-HQ-OPP-2014-0224--0012. 

1. Comment: BASF Corporation, the imazaquin technical registrant, is a FESTF member 

and is entitled to rely on the FESTF data. 

Response: The Agency thanks FESTF for its comment, and will consider the FESTF 

data during the imazaquin registration review. 

Comments submitted by CBD in EPA-HQ-OPP-2014-0224-0013. 

2. Comment: The Center for Biological Diversity's (CBD) comments focus on the EPA's 

duty to consult with the US. Fish and Wildlife Service and the National Marine Fisheries 

Service (the Services) on the registration review of imazaquin in accordance with the 

Endangered Species Act (ESA). The CBD comments mention various aspects of the risk 

assessment process, including use of the best available data to develop endangered 

species risk assessments, and evaluation of effects on endangered and threatened species 

and their designated critical habitat. CBD also expresses concern regarding the rigor of 

the Agency's preliminary determinations regarding the effects of imazaquin on 

endangered and threatened (listed) species and their designated critical habitat for the 

imazaquin registration review. 

Response: EPA has reviewed the comments from CBD on the registration review docket 

opening for imazaquin and plans to address many of the concerns raised by CBD as part 

ofthe implementation plan for assessing the risks of pesticides to listed species based on 

the recommendations of the April2013 National Academy of Sciences (NAS) report. 

EPA wi 11 address concerns specific to imazaquin in connection with the development of 

its final registration review decision for this pesticide. 

In November 2013, the EPA, along with the Services and the USDA, released a summary 

of their joint Interim Approaches for assessing ·risks to endangered and threatened (listed) 

species from pesticides. The Interim Approaches were developed jointly by the agencies 

in response to the NAS recommendations and reflect a common approach to risk 

assessment shared by the agencies as a way of addressing scientific differences between 

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the EPA and the Services. The NAS report outlines recommendations on specific 

scientific and technical issues related to the development of pesticide risk assessments 

that EPA and the Services must conduct in connection with their obligations under the 

ESA and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on 

November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the 

December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues 

Research and Evaluation Group (SFIREG) meetings. The agencies also held a 

stakeholder workshop in April and October 2014, allowing additional opportunities for 

stakeholders to comment on the Interim Approaches. Additional workshops are planned 

to enhance stakeholder involvement. As part of a phased, iterative process for 

developing the Interim Approaches, the agencies will also consider public comments on 

the Interim Approaches in connection with the development of upcoming registration 

review decisions. The details of the joint Interim Approaches are contained in the white 

. Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 

2013 Report, dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward impleq1entation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the ecological problem formulation supporting this Final Work 

Plan for imazaquin does not describe the specific ESA analysis, including effects 

determinations for specific listed species or designated critical habitat, to be conducted 

during registration review. In the ecological problem formulation document for 

imazaquin, EPA described the screening-level risk assessment to determine the potential 

effects of imazaquin on all taxa of non-target wildlife and plants, which will assume that 

listed species and their designated critical habitats may be present in the vicinity of the 

application of imazaquin. This screening-level assessment will allow EPA to focus its 

future evaluations on the types of species where the potential for effects exists once the 

scientific methods being developed by the agencies have been fully vetted. While the 

agencies continue to develop a common method for ESA analysis, the planned screeninglevel risk assessment for the registration review of imazaquin will describe the level of 

ESA analysis completed for this particular registration review case. Once the agencies 

have fully developed and implemented the scientific methods necessary to complete risk 

assessments for endangered and threatened (listed) species and their designated critical 

habitats, these methods will be applied to subsequent analyses for imazaquin as part of 

completing this registration review. 

Comments submitted by Project Apis m. in (PAm) EPA-HQ-OPP-2014-0224--0014. 

3. Comment: The comments from PAm focus on the development of a federal strategy to 

protect honey bees and other pollinators. PAm comments indicated that they are the 

largest non-governmental, non-profit honey bee research funding organization in the 

US., and that they earned the respect of the nation 's commercial beekeepers and the top 

bee scientists in the country. PAm also indicated that they are the 'go-to ' organization at 

the interface of honey bees and pollinated crops. PAm derives its name from Apis 

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mellifera, the scient~fic name for the European honey bee. They expressed their 

willingness to coordinate new honey bee health programs and would be pleased to assist 

with, coordinate, or mange new federal initiatives. 

Response: The Agency thanks PAm for its comment and will consider this information 

as it conducts the registration review of imazaquin. 

PLANNED DATA NEEDS 

Table 1 below summarizes the planned data needs for imazaquin based on the Registration 

Review: Preliminary Problem Formulation for Environmental Fate, Ecological Risk, 

Endangered Species, and Human Health Drinking Water Exposure Assessments for Imazaquin 

and the Ammonium Salt of lmazaquin and lmazaquin: Human Health Risk Assessment Scoping 

Document in Support of Registration Review. The planned data needs have changed from what 

was included in the PWP. The planned data needs for imazaquin include the new pollinator data 

requirements. 

Table 1: Planned Data Needs for the Imazaquin Registration Review 

Estimated 

Guideline Number-1 Study Title3 Timeframe 

Test (Months from Material receipt of DCI) 

Anticipated Data Needs for the Parent Imazaquin 

875.2100 TurfTransferable Residue TEP 12 

835.1230 Batch equilibrium TGAI 12 adsorption/desorption 

835.2410 Photodegradation on soil TGAI 12 

835.2240 Photodegradation in water TGAI 12 

835.4100 Aerobic soil metabolism (three TGAI 24 additional soils) 

835.4300 Aerobic aquatic metabolism TGAI 24 

835.4400 Anaerobic aquatic metabolism TGAI 24 

Environmental Chemistry Method 

850.6100 (ECM) and Associated Independent TGAI 12 Laboratory Validations (IL V) for 

residues in water 

850. 1025 or 850.1055 Acute toxicity estuarine and marine TGAl 12 

organisms (mollusk) 

850.1035 or 850.1045 Acute toxicity estuarine and marine TGA1 12 

organisms (invertebrate) 

3 On June 27, 20 12, EPA announced certain revisions in harmonized guideline series 850 - Ecological Effects Tests 

- including renumbering and other designations or changes for some guideline studies. See "Final Test 

Guidelines; OCSPP 850 Series; Notice of Availability" 77 FR 38282, June 27,2012. 

http://www .regulation s.gov/#! documentDetai I ;D=EP A -HO-OPPT -2009-0 154-0028 

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Table 1: Planned Data Needs for the Imazaquin Registration Review 

Estimated 

Guideline Nnmbe.-1 Study Titlel Timeframe 

Test (Months from Material receipt of DCI) 

850.1075 Saltwater fish acute toxicity TGAI 12 

850.1300 Freshwater invertebrates life-cycle TGAI 12 

850.1350 Saltwater invertebrates life-cycle TGAI 12 

850. 1400 Freshwater fish early-life stage TGAI 12 

850.1400 Saltwater fish early-life stage TGAI 12 

850.2300 Avian reproduction (upland species and TGAI 24 waterfowl) 

850.4400 Aquatic plant growth (Tier II vascular TGAI 12 plants) 

850.4500 Aquatic plant growth (Tier II algae (3 TGAI 12 species) 

850.4550 Aquatic plant growth (Cyanobacteria) TGAI 12 

850.3020 (Tier 1)4 Honey bee adult acute contact toxicity TGAI 12 

850.3030 (Tier 1)4 Honey bee toxicity of residues on 

TEP 12 foliage 

850.3040 (Tier 2 or 3t Field testing for pollinators TEP 12 

Non-guideline, OECD Honey bee larval acute oral toxicity TGAI 12 

TG 2375

•

6 

Non-guideline5

• 

6

• 

7 Honey bee larval chronic oral toxicity TGAI 24 

Non-guideline, OECD Honey bee adult acute oral toxicity TGAI 12 

TG 2136 

Non-guideline 6

• 

7 Honey bee adult chronic oral toxicity TGAI 24 

Non-guideline (Tier 2) 6 Semi-field testing for pollinators TEP 12 (tunnel or colony feed ing studies) 

Non-guideline (Tier 2) 6 Field trial of residues in pollen and TEP 12 nectar 

TGAI = techmcal grade acttve mgredtent; TEP = typtcal end-use product; 

4 Toxicity Testing Requirements for Bees as Specified in 40 CFR Part I 58. 

5 A 21-day larval toxicity study may be sufficient to assess both acute and chronic toxicity to developing brood. 6 Additional Recommendations for Bee Testing. 7 A protocol should be submitted to the Agency for review and approval prior to study initiation. 

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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 imazaquin. For human health, EPA 

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

review. If toxicological endpoints or points of departure are revised based on the data that are 

required for registration review, 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 

Registration Review: Preliminary Problem Formulation for Environmental Fate, Ecological 

Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for 

Imazaquin and the Ammonium Salt of Imazaquin and Jmazaquin: Human Health Risk Assessment 

Scoping Document in Support of Registration Review. The planned assessments have not 

changed from what was included in the PWP. 

Table 2: Planned Risk Assessments for the Imazaquin Registration Review 

Type of Risk Conduct? Notes Assessment 

Ecololdcal and Environmental Fate 

Comprehensive y 

ecological (species to 

be assessed include 

terrestrial and aquatic 

organisms), including 

endangered species 

Incidents Will check for For a discussion of reported ecological incidents for 

updates imazaquin, see page 11 ofthe Problem Formulation. 

Human Health 

Dietary 

Food N The dietary exposure database is adequate. At this 

time, a revised dietary risk assessment is not 

anticipated for imazaquin, provided there are no 

significant changes to the toxicological points of 

departure (POD), uncertainty factors, and no 

significant changes to the estimated drinking water 

concentrations (EDWCs). 

Drinking water y The Agency anticipates updating the drinking water 

assessment under re~stration review. 

Occupational 

Handlers (mixers, y Occupational handler and post-application exposure 

loaders, applicators) assessments will be performed under registration 

Post-application y review using current policies. Any changes to the 

toxicological POD or uncertainty factors will also be 

incorporated. 

Residential 

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Handlers y A revised residential exposure assessment using the 

Post -application y 2012 Residential SOPs will be needed during 

registration review. Any revisions to toxicological 

POD or uncertainty factors will be incorporated. The 

need for a volatilization risk assessment will be 

examined during registration review. 

Other 

Aggregate y Evaluates the .combined risk from dietary and 

residential exposures. Revised aggregate risk 

assessments will be performed for imazaquin if there 

are any changes to toxicological POD or uncertainty 

factors, or if there are any significant changes to the 

revised residential exposures or significant changes to 

the EDWCs. 

Cumulative N EPA has not made a determination of whether 

imazaquin has a common mechanism of toxicity with 

other substances. Therefore, a cumulative risk 

assessment has not been performed for imazaquin. 

Tolerances y During registration review, the Agency anticipates 

modifying the U.S. tolerance definition for 

imazaquin. There are currently no international 

maximum residue limits (MRLs) for imazaquin; 

therefore, there are no harmonization issues with 

Codex, Canada, or Mexico. 

Incidents Will check for For a discussion of reported human incidents for 

updates imazaquin, see page 10 of the Scoping Document and 

the Imazaquin: Tier I Review of Human Incidents. 

TIME LINE 

EPA has created the following estimated timeline for the completion of the imazaquin 

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

Table 3: Projected Imazaquin Registration Review Timeline 

Activities Estimated Date 

Opening the Docket 

Open Docket and 60-day Public Comment Period Sept. 2014 - Completed 

Close Public Comment Nov. 2014 - Completed 

Case Development 

Final Work Plan March 20 15 - Completed 

Issue DCI 2015 April - June 

Data Submission 2017 April - June 

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Table 3: Projected Imazaquin Registration Review Timeline 

Activities Estimated Date 

60-day Public Comment Period for Draft Risk 2018 Oct. - Dec. 

Assessments8 

Registration Review Decision 

60-day Public Comment Period for Proposed 2019 July- September 

Registration Review Decision 

Registration Review Decision and Begin Post-Decision 2020 

Follow-up 

Total (years) 6 

As noted previously, the Agency plans to require several environmental fate, ecological effects, 

and human health studies for imazaquin through a Data Call-In Notice, expected to be issued in 

June 2015. 

8 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. 

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