Docket Number EPA-HQ-OPP-2014-0279 

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Imazapic Preliminary Work Plan 

Registration Review: Initial Docket 

Case Number 7234 

September 2014 

Approved by: P~N~"'~` 

Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

Date: 9-- 11— ":9D /y 

Imazapic Preliminary Work Plan — Table of Contents 

OVERVIEW................................................................................................................................... 4 

ANTICIPATEDDATA NEEDS .................................................................................................... 5 

STATUTORY AND REGULATORY AUTHORITY ................................................................... 6 

CHEMICALFACTS ...................................................................................................................... 6 

USE AND USAGE INFORMATION ............................................................................................ 7 

RECENTACTIONS ....................................................................................................................... 8 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW ................................ 8 

TIMELINE.................................................................................................................................... 11 

NEXTSTEPS ............................................................................................................................... 12 

Appendix — Additional Areas Considered in the Imazapic Registration Review ..................... 13 

References: 

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

based on the following documents: 

1. Problem Formulation for Ecological Risk and Environmental Fate, Endangered Species, 

and Drinking Water Assessments for Imazapic and its Ammonium Salt. Michael Wagman 

and Iwona L. Maher. September 12, 2014. 

2. Imazapic (129041) and the Ammonium Salt of Imazapic (128943); Human Health 

Assessment Scoping Document in Support of Registration Review. William D. Wassell, 

Anwar Dunbar, and Lata Venkateshwara. September 4, 2014.. 

3. Imazapic and Imazapic Ammonium: Tier 1 Review of Harman Incidents. Elizabeth Evans 

and Shanna Recore. July 31, 2014. 

4. BEAD Chemical Profile for Registration Review: Imazapic (129041) and Imazapic-ammonium 

(128943). Sunil Ratnayake. July 10, 2014. 

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5. Imazapic (129041) and Imazapic-ammonium (128943) Case Level Screening Level U.sage 

Analysis (SLUA). Apri13, 2014. 

6. EFED Table I Report for Imazapic Ammonium (128943). June 10, 2014. 

7. EFED Table 1 Report for Imazapic (129041). June 16, 2014. 

8. HED Master Label Report for hnazapic- Ammonium (128943). June 10, 2014. 

9. HED Master Label Report for Imazapic (129041). June 16, 2014. 

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

the docket EPA-HQ-OPP-2014-0279 at http://w-w-w.regulations.gov . 
OVERVIEW 

The docket for imazapic and imazapic ammonium (imazapic) is now open, initiating the first 

public comment period for this registration review (docket number EPA-HQ-OPP-2014-0279). 

This case includes the following active ingredients: imazapic (PC Code 129041) and imazapicamonium (PC Code 128943). Imazapic is a systemic herbicide belonging to the imidazolinine 

class of pesticide, which share a common mechanism of action that involves the inhibition of 

acetolactate synthase (ALS) enzyme, an enzyme found in plants. Imazapic is registered to 

control certain grasses and broadleaf weeds on peanuts, grass (pasture and rangeland) and a wide 

range of non-crop areas including utility right-of-ways, airports, turf, , and recreational (nonresidential) sites. This Preliminary Work Plan (PWP) document explains what EPA's Office of 

Pesticide Programs knows about imazapic, 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 

imazapic. 

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 imazapic and what types of new data or other 

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

imazapic. 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 this chemical. 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 listing the anticipated data needs for imazapic. Next, it 

discusses the statutory and regulatory authority for Registration Review. Then the document 

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

assessments, and a projected registration review timeline for imazapic. Finally, the Appendix to 

this document includes identification and discussion of some areas that are considered generally 

in Registration Review along with some additional chemical case-specific information. 

9 
ANTICIPATED DATA NEEDS 

Table 1 below summarizes anticipated data needs for imazapic. For additional discussion of the 

anticipated data needs, see the Problem Formulation for Ecologfcal Rfsk and Environmental 

Fate, Endangered Species, and Drinking Water Assessments for Imazapic and its Ammonium 

Salt. 

Table 1: Anticipated Data Needs for the Imazapic Registration Review 

Estimated 

Guideline Study Title` 

Timeframe 

Number Test Material (Months from 

receipt of DCI) 

830.6317 Storage Stability (soil) TGAI 12 

835.4100 Aerobic Soil Metabolismz TGAI 24 

835.4200 'Anaerobic Soil Metabolism TGAI 24 

835.4300 Aerobic Aquatic Metabolism TGAI 24 

850.2100 Avian Acute Oral Toxicity Test3 TGAI 12 

Non- Pollinator Acute Oral Toxicity - Honeybee TGAI 12 guideline Adult4 

Non- Pollinator Chronic Oral Toxicity — Honey TGAI 12 guideline Bee Adult4 

Non- Pollinator Acute and Chronic Oral Toxicity — TGAI 12 guideline Honey Bee Larvae4 

850.3040 Field Testing for Pollinatorss TEP 24 

850.4100 Seedling Emergence and Seedling Growthb TEP 12 

850.4150 Vegetative vigor TEP 12 

Environmental chemistry methods and associated 

850.6100 independent laboratory validations for soil and TGAI 12 

water 

TGAI = technical grade active ingredient; TEP = typical end-use product; 

I On June 27, 2012, 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.regulations.Pov/#! documentDetai 1; D=E PA-H O-OPPT-2009-0154-0028 

z Need three additional soils. 

3Conducted with a passerine species. 

4A protocol should be submitted to the Agency for review prior to study initiation. 

5The need for this test may be waived pending the results of the requested lower tier pollinator tests. 

6Data is requested for tomato, oats and ryegrass. 

5 
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. 7 

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 imazapic. 

CHEMICAL FACTS 

Table 2 provides a summary of the chemical facts for imazapic. 

Table 2: Chemical Facts for Imazapic 

PC code 129041 and 128943 imaza ic- ammonium 

Case Number 7234 

CAS Number 104098-48-8 (imaza ic) and 10498-49-9 (imaza ic- ammonium) 

Year first re istered 1994 

Pesticide Type Herbicide 

Chemical class Imidazolinone 

Reregistration Eligibility 

Decision (RED) 

Because it was registered after November 1984, imazapic was not 

sub'ect to reregistration. 

Tolerance Reassessment 

Eligibility Decision 

(TRED) 

Not applicable 

Cumulative group Imazapic has not been identified as a member of a cumulative 

group that shares a common mechanism of toxicity. 

' http://www.epa.gov/oppsrrdl/registration_review/ 

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Table 2: Chemical Facts for Imazapic 

40 CFR Citation Tolerances for imaza ic are established in 40 CFR § 180.490. 

Dual-use Imazapic is registered for conventional pesticidal uses only and 

has no re istered antimicrobial or biopesticidal uses. 

Non- esticidal uses There are no identified non- esticidal uses of imazapic. 

Pesticide Re-evaluation Ricardo Jones 

Division, Chemical Jones. ricardo(Loepa. gov 

Review Manager 703-347-0493 

Registration Division, Kable Davis 

Product Manager Davis.kabler,epa.gov 

703-306-0415 

USE AND USAGE INFORMATION 

Table 3 summarizes the use and usage information for imazapic. Please see the BEAD Chemical 

Profrle for RegistYation Review: Imazapic (129041) and Imazapic-ammonium (128943) in the 

registration review docket for more details. 

Table 3: Imazapic Use and Usage Information 

Summary of Use Systemic herbicide used for the control of certain annual and 

perennial grasses and broadleaf weeds in peanuts, grass (pasture 

and rangeland) and non-crop lands. 

Use Sites Used on peanuts as early post-emergence treatment for weed 

control. Used on roadsides and utilities as a pre-emergent or postemergent treatment to control undesirable grass species. Used on 

commercial and recreational sites as a perimeter and spot 

treatment to control broadleaf weeds and undesirable grass 

species. Used as a residential spot treatment for weed control. 

Summary of Usage Imazapic used primarily on peanuts and pasture based on EPA 

data from the time period of 1998-2012. This data suggests that 

use on peanuts was variable during this time period, and use on 

pasture spiked in 2002, decreasing since through 2012. In 2012, 

peanuts constituted 98.6% of pounds applied to crops in the U.S., 

with approximately 42,600 total pounds applied. In addition, data 

provided by the Bureau of Land management shows that in 2011, 

the most recent year data was available, 21,194 pounds of 

imazapic were applied to BLM pasture and rangelands. There is 

no data available on non-agricultural (i.e. commercial, 

recreational, residential) usa e. 

Formulation Type(s) Granules, water-dispersible granules, soluble concentrates, and 

ready-to-use solutions. 

Application Method(s) Products can be applied by handheld sprayers, mechanical 

sprayers, and aerial application. 

Technical Registrant(s) I BASF Corporation and AGAN CHEM MFG, LTD 

7 
Table 3: Imazapic Use and Usage Information 

No. of Re istrations 23 Section 3 products 8 

Restricted Use I No 

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. 

Labels for EPA Reg. Nos. 71995-49 and 71995-51 are unclear with respect to application 

parameters such as the size of the treated area or maximum annual application 

rates. Without further information, EPA expects to use conservative assumptions to 

approximate these parameters in order to conduct a quantitative risk 

assessment. However, the Agency will work with registrants to clarify information on 

imazapic product labels, especially the maximum annual application rates for nonagricultural perimeter or spot-treatment uses. 

• Confirmation of the following label information: sites of application; formulations; 

application methods and equipment; maximum application rates; frequency of 

application, application intervals, and maximum number of applications per season; and 

geographic limitations on use. 

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

• Median and 90`" percentile reported use rates (lbs ai/A) from usage data — national, state, 

and county. 

• Typical application timing (date of first application and application intervals) — national, 

state, and county. 

• Usage/use information for non-agricultural uses. 

• Typical application interval (days). 

• State or local use restrictions. 

• Foreign technical registrants not listed above who supply technical imazapic to the US 

market. 

RECENT ACTIONS 

On August 16, 2014 an import tolerance (a tolerance without U.S. registrations) was established 

for imazapic on sugarcane (78 FR 49927), and on Apri14, 2014 an import tolerance was 

established for imazapic on soybean, seed (79 FR 18815). 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW 

The most recent comprehensive human health risk assessment for imazapic was completed on 

May 16, 2013 in response to a petition for import tolerances on sugarcane and geneticallymodified soybean. The most recent ecological and environmental fate risk assessment conducted 

by the EPA was completed in 2001 for new use on pasture and rangeland. Findings and 

conclusions from these risk assessments are summarized in the Problem Formulation for 

Ecological Risk and Environmental Fate, Endangered Species, and Drinking Water Assessments 

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

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

8 
for Imazapic and its Ammonium Salt and Imazapic (129041) and the Ammonium Salt of Imazapic 

(128943); Human Health Assessment 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 imazapic. 

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

occupational, and aggregate risk assessments during registration review. If toxicological 

endpoints or points of departure are revised based on the data that are anticipated to be 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 4 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and HED Scoping Document. 

0 
Table 4: Anticipated Risk Assessments for the Imazapic Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecolo ical and Environmental Fate 

Comprehensive ecological Y EFED will conservatively characterize this risk by 

(species to be assessed utilizing a TTR approach. In this approach, a single 

include terrestrial and aquatic exposure concentration is estimated for total residues 

organisms), including (i. e. parent imazapic + the five degradates identified 

endangered species in the aqueous photolysis study) and compared to a 

representative toxicity endpoint for the parent (i. e. 

assumes equal toxicity of each degradate to parent 

imaza ic 

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

updates imazapic, see page 22 of the EFED Problem 

Formulation. 

Human Health 

Dietary 

Food Y In the most recent risk assessment done in 2013, 

chronic dietary exposures were not of concern to 

HED. 

Drinking water Y A revised dietary exposure analysis may be required 

to reflect the most recent dietary exposure models and 

potential revised estiniated drinking water 

concentrations. 

Occu ational 

Handlers (mixers, loaders, Y Occupational handler inhalation exposure assessments 

applicators) need to be performed for the scenarios that have not 

been previously assessed. 

Post-application Y The need for a quantitative occupational postapplication inhalation exposure assessment will be 

considered during registration review. 

Residential 

Handlers Y The residential handler assessment may need to be 

revised based on new residential handler SOP's and 

policy changes for body weights and toxicological 

endpoints. 

Post-application N Residential post-application assessments do not need 

to be performed if label directions indicate the turf 

use is a specific spot treatment as in the case of 

imaza ic. 

Other 

Aggregate Y A new aggregate risk assessment may be required 

during Registration Review to incorporate any revised 

dietary exposure analyses and/or residential exposure 

assessments. 

10 
Cumulative N EPA has not made a common mechanism of toxicity 

finding for imaza ic and any other substances. 

Tolerances N The qualitative nature of imazapic residues in plants 

and livestock is adequately understood. 

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

updates imazapic, see page 10 of the Scoping Document and 

the Imazapic and Imazapic Ammonium: Tier I Review 

of Human Incidents. 

Guidance for Commenters: Additional ecological information requested for this 

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

• Information on a typical percentage of an area that is spot treated for non-agricultural 

uncultivated areas/soils. 

• 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 imazapic registration 

review in Table 5 below. 

Table 5: Projected Imazapic Registration Review Timeline 

Activities Estimated Date 

O ening the Docket 

O en Docket and 60-day Public Comment Period 2014 September 

Close Public Comment 2014 November 

Case Develo ment 

Final Work Plan 2015 February 

Issue DCI 2015 A ril - June 

Data Submission 2017 April - June 

60-day Public Comment Period for Draft Risk 

Assessments9 

2018 October - December 

Re istration Review Decision 

60-day Public Comment Period for Proposed 

Re istration Review Decision 

2019 April - June 

Registration Review Decision and Begin Post-Decision 

Follow-u 

2019 

Total (years) 5 

9The 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. 
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 imazapic. 

12 
Appendix — Additional Areas Considered in the Imazapic 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: 

Imazapic is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act. 10In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for imazapic. 11More information on impaired water bodies and TMDLs 

can be found at the Agency's website. 12The Agency invites submission of water quality data 

for this pesticide. 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 they can be used quantitatively or qualitatively in pesticide risk 

assessments. 

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 imazapic 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: 

10http://iaspub.epa .!-,rov/tmdl watersl0/attains nation cy.cause detail 303d?p cause group id=885 

llhttp://iaspub.epa.5,~ov/tmdl watersl0/attains nation.tmdl pollutant detail?p pollutant group id=885&p pollutant 

group naine=PESTICIDES 

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13http://www.epa.gov/oppsrrdl/registration review/water qualitX sop.htm 

13 
A risk assessment that supports a complete endangered species determination has not been 

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

allow the Agency to determine whether use of imazapic 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 its most recent registration decision for imazapic, 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), imazapic 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 

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. A second list 

of chemicals identified for EDSP screening was published on June 14, 2013 14and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither- of these lists 

should be construed as a list of known or likely endocrine disruptors. 

14See http://www.reQulations.aov/#!docutnentDetail;D=EPA-HO-OPPT-2009-0477-0074 for the final second list of 

chemicals. 

14 
For further information on the status of the EDSP, the policies and procedures, the lists of 

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

website. ~ 5 

HUMAN STUDIES: 

Occupational and Resfdential 

Past imazapic 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. 

15http://www.epa.gov/endo/ 

15