2 

### Table of Contents

Contents

I. Introduction

................................ ................................ ................................ ............................. 3

II. Scientific Assessments

................................ ................................ ................................ ............ 4

A. Human Health Assessment

................................ ................................ ................................ .... 4

B. Environmental Assessment

................................ ................................ ................................ ... 4

Pollinator Studies and Assessment

................................ ................................ ......................... 5

Endangered Species Assessment

................................ ................................ ............................ 5

C. Endocrine Disruptor Screening Program

................................ ................................ ............... 6

III. Interim Registration Review Decision

................................ ................................ ................. 7

IV. Next Steps and Timeline

................................ ................................ ................................ ...... 73



### I. Introduction

This document is the Environmental Protection Agency’s (EPA or the Agency) Interim Registration Review Decision for i mazapyr (imazapyr (PC 128821) and the isopropylamine salt (PC 128829) of imazapyr) and is being issued pursuant to 40 CFR sections 155.56 and 155.58

. A registration review decision is the Agency's determination whether a pesticide meets, or does not meet, the standard for registration in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it determines it to be appropriate, a n interim registration review decision before completing a registration review. Among other things, the interim registratio n review decision may require new risk mitigation measures, impose interim risk mitigation measures, identify data or information required to complete the review, and include schedules for submitting the required data, conducting the new risk assessment an d completing the registration review. For further information on i mazapyr , additional documents can be found in EPA’s public docket (EPA

- HQ

- OPP

- 2014

- 0200 ) at www.regulations.gov

.

FIFRA, as amended by the Food Q uality Protection Act (FQPA) of 1996, mandated the continuous review of existing pesticides. All pesticides distributed or sold in the United States generally must be registered by the EPA based on scientific data showing that they will not cause

unreasona ble risks to human health or to the environment when used as directed on product labeling. The registration review program is intended to make sure that, as the ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard of no unreasonable adverse effects. Changes in science, public policy, and pesticide use practices will occur over time. Through the registration review program, the Agency periodically reevaluates pestici des to make sure that as these changes occur, products in the marketplace can continue to be used safely. Information on this program is provided as http://www.epa.gov/pesticide

- reevaluation/registration

- review

- process

.

In 2006, the Agency implemented the registration review program pursuant to FIFRA section 3(g) and will review each registered pesticide every 15 years to determine whether it

continu es to meet the FIFRA standard for registration.

Imazapyr is a non

- selective systemic herbicide registered for use as pre

- and post

emergent treatments to control broad spectrum terrestrial and aquatic weeds including terrestrial annual and perennial grass es
, broadleaf weeds

, herbs

, woody species

, and riparian and emergent aquatic weed species. The first product containing imazapyr was registered in 1984

. The Reregistration Eligibility Decision document (RED) for i mazapyr was completed in June 2006

.

Pursua nt to 40 CFR section 155.50, EPA formally initiated registration review for

i mazapyr (case 3078 )

. The following highlights significant events that have occurred during the registration review of imazap y r :

 June 25, 2014

– Publication of the I mazapyr Preliminary Work Plan for a 60

- day public comment period . The P reliminary W ork P lan (PWP) was accompanied by the scoping document and problem formulation.

 December 3, 2014

- Final Work Plan (FWP) for imazapyr was issued

– Three public

comments were receiv ed during the 60

- day comment period for the I mazapyr PWP

. None4

of the public comments resulted in changes to the anticipated registration review data needs, risk assessments, or timeline.

o The FWP noted that no additional data were needed and that no ecological or

human health risk assessments would be conducted for the imazapyr registration review because sufficient information was available to support a proposed registration review decision, pursuant to 40 CFR section 155.53( c ) (2)

.

 August 10, 2015

– The Agency publish ed the Imazapyr Proposed Interim Registration

Review Decision in docket number EPA

- HQ

- OPP

- 2014

- 0200 for a 60

- day public comment period. No comments were received during th at period.

 November 2015

– The Agency is now publishing the Imazapyr Interim Registration Review Decision, dated November 2 3 , 2015 in docket number EPA

- HQ

- OPP

- 2014

- 0200

.

Additional information on i mazapyr can be found in EPA’s public docket

, EPA

- HQ

- OPP

2014

- 0200 , accessed at www.regulations.gov

.



### II. Scientific Assessments

A. Human Health Assessment

As indicated in the FWP

, EPA did not require a risk assessment for registration review because after reviewing the toxicology databa se for imazapyr, EPA has not identified any human health endpoints of toxicological concern and, as a result, has determined that there are no risks of concern for dietary, residential, and occupational exposure

. Further discussion regarding these

conclusions can be found in the Imazapyr, Isopropylamine Salt: Registration Review Scoping Document for Human Health Assessment , which is available in the imazapyr docket

, EPA

- HQ

OPP

- 2014

- 0200, accessed at www.regulations.gov

.

B. Environmental Assessment

As indicated in the FWP, b ecause there were no significant changes since the last imazapyr ecological risk assessment, an upda ted or revised risk assessment for registration

review wa s not needed

.

While the last comprehensive risk assessment identified risk to non

- target terrestrial plants; t here was no risk to terrestrial plants from drift exposure alone for the corn use (the largest use at over 80% of lbs/a.i. applied ). Although there was some potential risk to some plants in adjacent fields and som e exceedances for non

- crop uses, l abel mitigation required in the RED (see the label table 1 ) to reduce spra y drift and now on product labels ha s greatly reduced potential risk, as it include d , among other things, requirements for the use of coarse or very coarse droplets

. Risk to aquatic vascular plants was indicated, but such plants are the target pest for aqu atic uses of imazapyr.

1 Available at http://archive.epa.gov/pesticides/reregistration/web/pdf/imazapyr_red.pdf5

Pollinator Studies and Assessment

When initially scoping the registration review for imazapyr, EPA did not identify the need for any additional studies to evaluate potential effects on pollinators. However, since the

issuance of the June 2014 Guidance for Assessing Pesticide Risks to Bees 2 , EPA has begun to require these data where applicable. EPA is currently determining whether additional pollinator data are needed for active ingredients in registration review whose dockets open ed prior to June

2014. For those active ingredients where EPA determines that additional pollinator exposure and effects data are necessary to help make a final registration review decision , EPA intends to issue

a DCI to obtain these data. In the near fut ure, EPA will provide further information and guidance on this effort. The pollinator studies that could be required are included in Table 1

below

. The Agency will require data it believes are needed to help inform the pollinator risk

assessment.

Table 1. Potential Pollinator Data Requirements

Guideline # Study

850.3030 * Honey bee toxicity of residues on foliage

850.3040 ** Field testing for pollinators

Non

- Guideline * (OECD 213) Honey bee adult acute oral toxicity

Non

- Guideline * (OECD 237) Honey bee larvae acute oral toxicity

Non

- Guideline * Honey bee adult chronic oral toxicity

Non

- Guideline * Honey bee larvae chronic oral toxicity

Non

- Guideline ** R esidues in pollen and nectar /field residue analysis

Non

- Guideline ** (OECD 75) Semi

- field testing for pollinators (tunnel or colony feeding studies)

*Tier 1 (Laboratory

- based studies) **Tier 2 and 3 (Semi

- field and full field colony

- level studies) The need for a higher tier test for pollinators will be determined based upon lower

- tiered tests and/or other lines of data and the need for a refined pollinator risk assessment.

Endangered Species Assessment

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 National Academy of Sciences’ (NAS) recommendations and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences between the

EPA and the Services. The NAS report 3 outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that EPA and the

Services must conduc t in connection with their obligations under the ESA and FIFRA.

2 http://www2.epa.gov/sites/production/files/2014

- 06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf

3 http://www.nap.edu/catalog.php? record_id=183446

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 Pestic ide Program Dialogue Committee (PPDC) and State

- FIFRA Issues Research and Evaluation Group (SFIREG) meetings. The agencies also held stakeholder workshops in April and October 2014, allowing additional opportunities for stakeholders to

comment on the Inter im 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 paper “Interim Approaches for National

- Level Pesticide Endangered Species Act Assessments Based on the Recommendations of t he National Academy of Sciences April 2013 Report” 4 , dated November 1, 2013.

Given that the agencies are continuing to develop and work toward implementation of the Interim Approaches to assess the potential risks of pesticides to listed species and their designated critical habitat, this Interim Decision for Imazapyr does not contain an ESA analysis that includes effects determinations for specific listed species or designated critical habitat . Once the agencies have fully developed and implemented t he 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 imazapyr as part of completing this registration re view.

C. 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, incl uding 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 reproduc tive effects in different taxonomic groups. As part of its most recent registration decision for imazapyr , 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), imazapyr 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 ingredi ents) 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 foun d to have the

4 http://www.epa.gov/espp/2013/nas.html7

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 an y 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 Febr uary 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 5 and includ es some pesticides scheduled for Registration Review and chemicals found in water. 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, p lease visit our website. 6

In this interim decision , EPA is making no human health or environmental safety findings associated with the EDSP screening of imazapyr . Before completing this Registration Review, the Agency will make an EDSP FFDCA section 40 8(p) determination.



### III

. Interim Registration Review Decision

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this

I nterim R egistration R eview D ecision. Except for the EDSP, ESA, and pollinator components of this case, EPA’s Interim Registration Review Decision for imazapyr is that (1) no additional data are required at this time; and (2) no changes to the affected registrations or their labeling are

needed at this time

.

In this interim registration review decision, EPA is making no human health or environmental safety findings associated with the EDSP screening of imazapyr, nor is it making an endangered species finding. EPA’s registration review decision for imazapyr will depend upon the result of an EDSP FFDCA section 408 (p) determination, complete pollinator determination, and ESA determination.



### I V. Next Steps and Timeline

A. Interim Registration Review Decision

A Federal Register Notice will announce the availability of this Interim Registration

Review Decision for imaz a pyr . A final decision on the imazapyr registration review case will occur after an EDSP FFDCA section 408(p) determination, complete pollinator determination,

and ESA determination.

5 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of

chemicals.

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