2 INTRODUCTION

This is the Environmental Protection Agency’s (E PA or the Agency) Final Work Plan (FWP) for the registration review of imazapyr (imazapyr a nd the isopropylamine salt of imazapyr). This work plan addresses public comments rece ived concerning the Preliminary Work Plan (PWP), which was posted in the imazapyr registrati on review docket (EPA-HQ-OPP-2014-0200). This case includes the following ac tive ingredients: imazapyr (PC code 128821) and the isopropylamine salt (PC code 128829) of imazapyr, the two collectivel y hereafter referred to as imazapyr. Imazapyr is a non-selective systemic he rbicide registered for use as pre- and postemergent treatments for control of a broad spectrum of terrestrial and aquatic weeds.

The Agency is implementing the registration revi ew 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 th e FIFRA standard for registration. Changes in science, public policy, and pesticide use practices occur over time. The registration review program is intended to make su re that, as the ability to assess risk evolves and as policies and practices change, al l registered pesticides continue to meet the statutory standard. The public phase of registration review begins wh en 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 wa s issued. Next is a summary of substantive comments received during the public comment peri od 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 comme nts. This section is followed by registration review planned data needs, risk assessments expected to be conducted, and the projected registration review timeline for imazapyr. Last ly, there is a discus sion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

EPA believes at this time that an updated eco logical risk assessment is not required for registration review. There have been no changes to th e use pattern and no new ecological effects or environmental fate data that changes the ove rall risk conclusions dr awn in the 2010 ecological risk assessment. The screening le vel risk assessment indicated risk to non-target terrestrial plants (monocots and dicots) and aquatic vascular plants from imazapyr use, based on the highest application rate from a va riety of use patterns.

This change in planned registra tion review risk assessments ha s resulted in a change in the projected registration review time line. Prior to completing the im azapyr registration review case, pursuant to the Endangered Species Act (ESA), EPA will conduct a comprehensive endangered species assessment for all uses of imazapyr.

1 http://www.epa.gov/oppsrrd1/registration_review/3 SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on th e imazapyr Preliminary Work Plan, which opened on June 25, 2014 and closed on Augus t 25, 2014, the Agency received 3 public comments. Comments were submitted by the Cent er for Biological Diversity (CBD), the FIFRA Endangered Species Task Force (FESTF), and an anonymous public citizen. The comments do not address the timeline described in the PWP, but 2 comments address the planned ecological risk assessment. In the PWP, EPA also so licited comments on the specific topics of environmental justice, water quality concerns, and trade ir ritants, but no comments or

information were received on those issues.

None of the public comments resulted in change s to the anticipated registration review data needs, risk assessments, or timeline. Summari zed public comments and Agency responses are in Responses to Public Comments on the Imazapyr Preliminary Work Plan . Public comments and EPA responses in their entirety are lo cated in the docket, EPA-HQ-OPP-2014-0200.

PLANNED DATA NEEDS

There are no planned data needs for imazapyr based on the Registration Review – Preliminary Problem Formulation for the Ecological Risk Assessment and Drinking Water Exposure Assessment to be Conducted for Imazapyr and Imazapyr Isopropylamine (PC Code 128829 (isopropylamine salt) and 128821 (imazapyr acid) and Imazapyr, Isopropylamine Salt: Registration Review Scoping Document for Human Health Assessment. The planned data needs have not changed from what was included in the PWP.

RISK ASSESSMENTS FOR REGISTRATION REVIEW

Because an updated screening leve l risk assessment is not neede d, during registration review the Agency will conduct a comprehensive endangered species assessment for all uses of imazapyr. For human health, EPA will not re quire a risk assessment for registration review because after reviewing the toxicology database for imazapyr, EPA believe s at this time that dietary, occupational, and residential exposures to imazapyr do not pose a significant human health risk and, therefore, risk assessments are not needed. This is because, althoug h there is potential for exposure to imazapyr and although the existing t oxicology studies do not use doses up to the limit dose, the available data are high quality and no hazard was identified from the toxicity studies. Prior to completing the imazapyr regist ration review case, pursuant to FFDCA section 408(p), EPA will make a determination regarding imazapyr under the Endocrine Disruptor Screening Program (EDSP). The Agency will also make a determination under the Endangered Species Act (ESA) prior to completing the imazapyr registration review case.

Table 1 below summarizes the planned registrati on review risk assessments based on the EFED Problem Formulation and HED Scoping Docume nt and has been updated since the PWP to reflect changes to the planned risk assessments.4 Table 1: Planned Risk Assessments for the Imazapyr Registration Review

Type of Risk Assessment Conduct? Notes

Ecological and Environmental Fate Comprehensive ecological (species to be assessed include terrestrial and aquatic organisms) N Because there have been no significant changes since the last ecological risk assessment, an updated or

revised risk assessment will not be conducted.

Comprehensive endangered species (species to be

assessed include terrestrial and aquatic organisms) Y A quantitative risk assessment will be conducted.

Incidents Will check for updates For a discussion of reporte d ecological incidents for imazapyr, see page 14 of the Problem Formulation.

Human Health Dietary Food N Because imazapyr does not pose a dietary (food and drinking water) risk, a quan titative dietary risk assessment is not required. Drinking water N

Occupational Handlers (mixers, loaders, applicators) N Because imazapyr does not pose an occupational risk, an updated or revi sed occupational risk assessment is not required. Post-application N

Residential Handlers N Because imazapyr does not pose a residential risk, an updated or revised residential risk assessment is not required. Post-application N

Other Aggregate N Evaluates the combined risk from dietary and residential exposures. Cumulative N Imazapyr has not been identified as a member of a cumulative group that shares a common mechanism of toxicity.

Tolerances N

Incidents Will check for updates For a discussion of reported human incidents for imazapyr, see page 5 of the Scoping Document and

the Imazapyr: Tier I Review of Human Incidents

.5 TIMELINE

EPA has created the following estimated timeline for the completion of the imazapyr registration review in Table 2 below. The projected timelin e has been updated to reflect changes to the planned risk assessments.

Table 2: Registration Review for Imazapyr – Projected Registration Review Timeline

Activities Estimated Date Opening the Docket Open Docket and 60-day Public Comment Period June 2014 – Completed Close Public Comment August 2014 – Completed Case Development

Final Work Plan December 2014 – Completed

Issue DCI N/A

Data Submission N/A 60-day Public Comment Period for Draft Risk Assessments N/A Registration Review Decision 60-day Public Comment Period for Proposed Interim Registration Review

Decision 2015 April - June

Registration Review Interim Decisi on and Begin Post-Decision Follow-up 2 2015 Total (years) 1

NEXT STEPS

After issuing the Final Work Plan, the Agency will prepare a Proposed Interim Registration Review Decision for imazapyr. The Agency exp ects to issue a Proposed Interim Registration Review Decision for a 60-day public comment period in 2015.

2 A final decision on the imazapyr regi stration review case, in accordance w ith 40 CFR Section 155.158, will occur after an EDSP FFDCA section 408(p) determination has been made as well as an ESA determination.