2 INTRODUCTION

This is the Environmental Protection Agency’s (E PA or the Agency) Final Work Plan (FWP) for the registration review of mesotrione. This work plan addresses public comments received concerning the Preliminary Work Plan (PWP), which was posted in the mesotrione registration review docket (EPA-HQ-OPP-2013-0779). Mesotrione is a pre and post-emergence selective herbicide registered for the control of broadl eaf weeds in many agricu ltural and non- agricultural

use sites.

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 scienc e, public policy, and pesticide us e 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 mesotrione. La stly, there is a discus sion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

As part of the problem formulation for th e ecological risk and drinking water exposure assessments for mesotrione (PC Code 122990; D417229), a review of the available ecotoxicological data was performed. While the cl assification for many of the submitted studies did not change after review (sti ll deemed Acceptable), the classifi cation for a number of aquatic toxicity studies did chan ge. Although these studies were recla ssified, the Agency does not expect to require additional data to upgrade th e studies at this time. Please see the Reclassification of 6 Mesotrione Aquatic Ecotoxicology Studies document for further detail.

The Agency recently finalized guidance on assessing risks to pollinators. 2 In keeping with the guidance, the Agency now expects to require, as a ppropriate, data that will enable an evaluation of the risks to different life stages of pollinators ( i.e. , adults and larvae). For mesotrione, the Agency expects to require the following data th at were not included in the Preliminary Work

Plan: acute and chronic oral toxic ity to larval honey bees and chr onic oral toxicity to adult honey

bees.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

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

2 http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance3 During the 60-day public comment period on the mesotrione Preliminary Work Plan, which opened on June 25, 2014 and closed on August 25, 2014, the Agency received three public comments. Comments were submitted by Syngenta Crop Protection, FESTF- FIFRA Endangered Species Task Force, and The Center for Biological Diversity. The comments do not address the timeline described in the PWP, but they do address the planned ecological and human health risk assessments and data requireme nts. In the PWP, EPA also solicited comments on the specific topics of environmental justice, water quality concerns , and trade irritants, however EPA only received co mments on trade irritants.

This section does not capture every comment made about the PWP nor all of the Agency’s responses. Summarized below ar e public comments that resulted in changes to the anticipated registration review data needs, risk assessments, or timeline, or are of a broader regulatory nature. Public comments and EPA responses in their entirety are locat ed in the docket, EPAHQ-OPP-2013-0779. Summarized public comments and Agency responses related to the anticipated ecological risk assessment or data needs are in the EFED Response to Comments Submitted to the Mesotrione Registration Review Docket (Docket ID: EPA-HQ-OPP-2013- 0779).

Comments submitted by Syngenta Crop Protection LLC in EPA-HQ-OPP-2013-0779-0012

Comment: In reference to Table 1 of the Prelim inary Work Plan, Syngenta Crop Protection provided data that had not been submitted to the Agency previously, additional information to support the various data submissi ons, and data waiver requests.

Response: EPA will review all of the recently submitted data, supporting rationales, and waiver requests to determine if the data and/or suppor ting rationale satisfy the anticipated data requirements and can be used in the re gistration review risk assessment.

Comment: Trade irritants: We have evaluated the me sotrione MRLs established in top export markets for cranberries, blueberries, caneberries, corn, sorghum, millet, oats, asparagus and soybean and have compiled this information in Appendix 1 to this document. Mesotrione is currently being reviewed for th e establishment of Codex MRLs and we believe that Codex MRLs
will be established in 2015.

Response: EPA will work to harmonize th ese MRL’s during registration review.

Comments submitted by FESTF- FIFRA En dangered Species Task Force in EPA-HQOPP-2013-0779-0011

Comment: The Preliminary Work Plan notes that an endangered species determination has not yet been completed. In response to the Agen cy’s endangered species da ta requirements, data developed by FESTF will address species proximity to mesotrione uses.

Response: The Agency is aware of the data developed by FESTF for mesotrione and when appropriate will use that data to fulfill data requirements.4 Comments submitted by The Center fo r Biological Diversity’s (CBD) in EPA-HQ-OPP2013-0779-0010.

Comment : The Center for Biological Diversity ’s (CBD) comments focus on the EPA’s independent duty under the Endangered Species Ac t (ESA) to consult with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) on the registration review of mesotrione.

Response : EPA plans to address the concerns raised by CBD as part of the implementation plan for assessing the risks of pesticides to listed species, which will be based on the recommendations of the April 2013 National Acad emy of Sciences (NAS) report. EPA will address concerns specific to mesotrione in c onnection with the developm ent of its registration
review decision.

At this time, EPA has not fully developed its ri sk assessment process for listed species. In November 2013, the EPA, along with the Services and the U.S. Department of Agriculture, released a summary of their joint Interim Appro aches for assessing risks to listed species from pesticides. The Interim Approach es were developed jointly by th e Agencies in response to the NAS recommendations and reflect a common ap proach to risk assessment shared by the Agencies as a way of addressi ng scientific differences between the EPA and the Services.

The NAS report, available at http://www.nap.edu/catalog.php?record_id=18344, outlines recommendations on specific scientific and tech nical issues related to the development of pesticide risk assessments that EPA and the Se rvices must conduct in connection with their obligations under the ESA and FIFRA. The joint In terim 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 Pes ticide Program Dialogue Committee (PPDC) and
State-FIFRA Issues Research and Evaluation Group (SFIREG) meetings, allowing additional opportunities for stakeholders to comment on the Interim Approaches. As part of a phased, iterative process for developing the Interim Appr oaches, the Agencies wi ll also consider public comments on the Interim Approaches in conn ection with the development of upcoming Registration Review decisions. Th e details of the joint Interim A pproaches are contained in the white paper “Interim Approaches for Nati onal-Level Pesticide Endangered Species Act

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report,” dated November 1, 2013, available at http://www.epa.gov/espp/2013/nas.html

.5 PLANNED DATA NEEDS

Table 1 below summarizes the planned da ta needs for mesotrione based on the Problem Formulation for the Environmental Fate, Ec ological Risk, Endangered Species, and Drinking Water Exposure Assessments in Support of the Registration Review of Mesotrione , and Response
to Comments documents . The planned data needs have not changed from what was included in

the PWP.

Table 1: Planned Data Needs for the Mesotrione Registration Review

Guideline

Number 3 Study Title 3 Test Material Estimated

Timeframe

(Months from receipt of DCI)

Data Needs for the Parent Mesotrione

835.4200 Anaerobic soil metabolism TGAI 24

835.4300 Aerobic aquatic metabolism TGAI 24 835.4400 Anaerobic aquatic metabolism TGAI 24

850.1350 Estuarine/Marine Invertebrate Chronic Toxicity Study TGAI 12

850.6100 Analytical method in soil and independent laboratory validation TGAI 12

Analytical method in water and sediment. and independent laboratory validation TGAI 12

Analytical methods with Storage Stability (additional information needed to support previously submitted surface water monitoring study MRID 47244503) TGAI 12

Nonguideline Drinking water treatmen t methods (additional information needed to support MRID 47578301 and previously submitted surface water monitoring study MRID 47244503) TGAI 8

Nonguideline Pollinator Acute Oral Toxicity – honey bee
larvae 4 TGAI 12

3 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 Av ailability” 77 FR 38282 , June 27, 2012. http://www.regulations.gov/#!documen tDetail;D=EPA-HQ-OPPT-2009-0154-0028

4 Draft protocol for the chronic oral toxicity study with honeybee larval should be submitted to EPA for review prior to initiation. EPA has not developed a guideline for these studies, but that the OECD is currently working on guidance for a 21-day larval toxicity study that can provide both acute and chronic oral toxicity data for bee larvae. When the guidance is finalized, EPA will indicate whether it may be used to satisfy a requirement for both
acute and chronic oral toxic ity data for honey bee larvae. Registrants ma y elect to submit a separate acute (single dose) larval toxicity study following the OECD guideline TG237, for acute: http://www.oecdilibrary.org/environment/test-no-237-honey-bee-apis-mellif era-larval-toxicity-test-si ngle-exposure_9789264203723-

en and for repeat dose:6 Table 1: Planned Data Needs for the Mesotrione Registration Review

Guideline

Number 3 Study Title 3 Test Material Estimated

Timeframe

(Months from receipt of DCI)

Nonguideline Pollinator Chronic Oral Toxicity – honey bee
larvae 4 TGAI 24

Nonguideline Pollinator Chronic Oral Toxicity – honey bee

adult 5 TGAI 24

Data Needs for the Degradates

835.4100 Aerobic soil metabolism MBNA 24 835.4300 Aerobic aquatic metabolism MBNA 24

850.1035 Estuarine/Marine invertebrate acute toxicity MNBA 12

850.6100 Analytical method in soil MNBA &

AMBA 12

Analytical method in water and sediment. MNBA &

AMBA 12

850.4100 Terrestrial Plant Seedling Emergence Tier II Study MNBA 12

TGAI = technical grade active ingredien t; TEP = typical end- use product; MNBA=4- (methylsulfony1)-2-nitrobenzoic acid; AMBA=2 -amino-4-(methylsulfonyl) benzoic acid

http://www.oecd.org/env/ehs/testing/Draft_GD_h oneybees_rep_exp_for_2nd_CR_25_November_2013.pdf

5 Draft protocol for the chronic study with adult honeybee should be submitted to EPA for review prior to initiation. OECD is developing study guidance for assessing the chronic (10-day) oral toxicity to the honey bee. Discussion of the study design elements for the 10-day adult toxicity test can be found in Appendix O of the European Food Safety Authority (EFSA) guidance document: EFSA. Guidance on the risk assessment of plant protection products on bees ( Apis mellifera

, Bombus spp. and solitary bees. EFSA Journal 2013;11(7):3295, 266 pp. doi:10.2903/j.efsa.2013.3295. Available online : www.efsa.europa.eu/efsajournal or at: http://www.efsa.europa.eu/en/efsajournal/doc/3295.pdf7 RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency will conduct a comprehensive ecological risk assessment, including an endangered species a ssessment, for all uses of meso trione. 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 base d on the data that are required for registration review and/or curren t policy, they will be considered in the new assessments, as well as any changes to the sta ndard operating procedures or default exposure assumptions.

Table 2 below summarizes the planned registrati on review risk assessments based on the EFED Problem Formulation and HED Scoping Docume nt, and the planned assessments have not changed from what was included in the PWP.8 Table 2: Planned Risk Assessments for Mesotrione 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 stressors of concern are mesotrione and mesotrione’s major degradates, MNBA and AMBA. A total toxic residues (TTR) approach will be used for the ecological risk assessment. The drinking water assessments conducted to support future human health risk assessments of mesotrione will incorporate modeling of the parent only in surface and groundwater. See page 26 of the Problem
Formulation for more detail.

Incidents Will check for updates For a discussion of reporte d ecological incidents for mesotrione, see page 23 of the Problem Formulation.

Human Health Dietary Food Y A revised dietary exposur e analysis may be required to reflect the most recent dietary exposure models, potential revised Esti mated Drinking Water Concentrations (EDWCs), and/or changes to the toxicological PODs. Drinking water Y

Occupational Handlers (mixers, loaders, applicators) Y Revised occupational handler assessments will be necessary to reflect maximu m application rates. In addition, assessments for all uses may be updated if toxicological PODs are revised. Post-application Y Revised occupati onal post-application assessments will be necessary to reflect all currently registered uses (including SLN registrations). In addition, assessments for all uses may be updated if toxicological PODs are revised.

Residential Handlers Y A higher application ra te for handheld equipment was identified during the label review process. This higher rate will need to be assessed. In addition, assessments for all uses may be updated if toxicological PODs are revised. Post-application Y May be updated if toxicological PODs are revised.

Other Aggregate Y New aggregate risk assessment may be required during registration review to incorporate revised dietary exposure analyses, revised residential exposure assessments, and/or changes to the toxicological PODs.9 Cumulative N Mesotrione has not b een identified as a member of a cumulative group that shares a common mechanism of toxicity in mammals. Tolerances Y Adequate methods ar e available for enforcement of the currently established tolerances. EPA will work to harmonize tolerances and MRLs during registration
review.

Incidents Will check for updates For a discussion of reported human incidents for mesotrione, see pages 10 and 11 of the Scoping

Document and the Mesotrione: Tie r I Review of

Hu man I nci dents.

TIMELINE

EPA has created the following estimated timeline for the completion of the mesotrione registration review in Table 3 be low. The projected timeline has not changed since the PWP.

Table 3: Registration Revi ew for Mesotrione – 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 Dec. 2014 - Completed

Issue DCI 2015: Jan.- March

Data Submission 2017: Jan.- March 60-day Public Comment Period for Draft Risk Assessments 6 [1] 2018: July – Sept. Registration Review Decision 60-day Public Comment Period fo r Proposed Registration Review

Decision 2019: April - June

Registration Review Decision a nd Begin Post-Decision Follow-up 2020 Total (years) 6

NEXT STEPS

As noted previously, the Agency plans to requ ire several environmenta l fate and ecological effects studies for mesotrione through a Data Call -In Notice, expected to be issued in January –
March of 2015.

6 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.