3 TRIBENURON METHYL FINAL WORK PLAN

Introduction

Thi s is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for the registration review of tribenuron methyl

. The FWP includes the expected registration review timeline. The FWP also addresses public comments received concerning the Preliminary Work Plan (PWP) in the Summary Document

, which was posted i n the tribenuron methyl registration review docket ( EPA

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, and any other comments concerning the initial docket postings

. The Summary Document provided information on what EPA knows about this pesticide and what additional risk analyses and data or information the Agency believes are needed to make a registration review decision.

The Agency ’s implementation of the r egistration r eview program requires review of eac h registered pesticide every 15 years to determine whether it continues to meet the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) standard for registration. Changes in science, public policy, and pesticide use practices will 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 that statutory standard. The public phase of registration review begins when the initial docket is opened for each case. Information on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/

. Tribenuron methyl is a sulfonylurea herbicide registered for use on cereal grains (barley, field corn, oats, rice, sorghum, and wheat), oilseed crops (canola, flax, and sunflower), soybeans, and cotton to control broadleaf weeds. There is also a tolerance with regional registration s for grass forage , fodder, and hay (except Bermuda grass forage and hay). There are no registered residential uses of tribenuron methyl

. Tribenuron methyl was first registered in 1989 ; therefore

, it was not subject to the reregistration requirements of FIFRA. In 2004, i n conjunction with the establishment of new tribenuron methyl tolerances ( 69 FR 56711

- 56718 ), EPA reassessed the existing tribenuron me thyl tolerances as required by the Food Quality Protection Act (F QPA )

. Updates Since the Preliminary Work Plan was Issue d

Two plant studies (GLNs 850.4150 and 850.5400) were erroneously listed as data requirements for the parent tribenuron methyl in the “Summary of Data Gaps

– Tribenuron Methyl” table in the March 2011 Tribenuron Methyl PWP. While Guideline 850.4150 remai ns a data gap for the tribenuron methyl degradates triazine amine, sulfonamide, and saccharin, it is not required for the parent tribenuron methyl. The table listing the data gaps for tribenuron methyl has been corrected in the “Summary of Data Gaps

– Tri benuron Methyl” section of the FWP.

To summarize, the following ecological data requirements are being removed from the table of data requirements for tribenuron methyl:4 **•** 850.4 1 5 0 Vegetative Vigor, Tier II (p arent tribenuron methyl only )

**•** 850.5400 Algal to xicity, Tier II

All other environmental fate and ecological effects data requirements remain as listed in the tribenuron methyl PWP.

Comments Received on the Preliminary Work Plan

The tribenuron methyl registration review docket was open for a 60

- day co mment period beginning on March 30, 2011. During the public comment period

, t he Agency received comments from E.I. DuPont Nemou r s & Co., Inc. (DuPont) and the Federal Endangered Species Task Force (FESTF). The comments received did not change the planned risk assessment, data needs, or the timeline detailed in the tribenuron methyl PWP

. EPA also solicited comments , through the PWP, on three specific topics: environmental justice, water body impairment, and trade irritants. No comments or information wer e received during the comment period on these topics.

A general overview of the comments and the Agency’s responses to the comments are presented in the “ Summary of Comments and Agency Responses ” section of this document

. The complete Agency responses can be found in EFED R esponse to Public Comments for Tribenuron m ethyl Preliminary Work Plan (PWP) located in the tribenuron methyl registration review docket (EPA

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R isk Assessment and Data Needs

The Agency will require data and will conduct a comprehensive ecological risk assessment, including an endangered species assessment, and will require data and conduct human exposure risk assessments for all uses of tribenuron methyl

. Below is a summary of the issues relevant to the registrat ion review of tribenuron methyl

.

E cological R isk :

**•** The most recent ecological risk assessment for tribenuron methyl w as completed in August 2009 for the registration of tribenuron methyl

- containing pesticides on herbicide

- tolerant field corn and soybean.

**•** An ecological risk assessment of all registered uses of tribenuron methyl will be conducted during registration review. The new assessment will incorporate the most
up

- to

- date modeling methodologies, updated toxicological endpoint s, and data submitted u nder the registration review data call

- in.

**•** The Agency has not conducted a risk assessment that supports a complete endangered species determination for tribenuron methyl. The ecological risk assessment planned during registration review will allow the Ag ency to determine whether tribenuron5 methyl ’s use 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.

**•** The Agency will requir e the following data for parent tribenuron me thyl in order to conduct the planned ecological risk assessment, including an endangered species
assessment :

**•** GDLN 835.6100

– Environmental Chemistry Analytical Methods and Independent Laboratory Validation (ILV) for Soil

**•** GDLN 835.6200

– Aquatic Field Dissipation (including Environmental Chemistry Methods and ILV for Soil and Water)

**•** GDLN 850.1025

– Oyster Acute Toxicity Test (shell deposition)

**•** GDLN 850.1300

– Invertebrate Life

- cycle Tox icity Test (freshwater)

**•** GDLN 850.1400

– Fish Early

- Life Stage Toxicity ( estuarine/marine )

**•** GDLN 850.2100

– Avian Acute Oral Toxicity Test (passerine)

**•** GDLN 850.4100

– Seedling Emergence (Tier II)

**•** GDLN 850.4400

– Aquatic Plant Toxicity Test using Lemna spp. (Tier II)

**•** NON

- GDLN

– Special Study for Non

- Target Plant Reproductive Toxicit y

**•** The Agency will require the following data for the major tribenuron methyl degradates :

o

- de n ethyl

- triazine amine; triazine amine; sulfonamide; and saccharin, in order to conduc t a complete ecological risk assessment, including an endangered species
assessment:

**•** GDLN 850.1300

– Invertebrate Life

- cycle Toxicity Test (freshwater; excluding o

- de n ethyl triazi ne amine)

**•** GDLN 850.4100

– Seedling Emergence (Tier II)

**•** GDLN 850.4150

– Vegetative Vigor (Tier II, excluding

o

- de n ethyl triazine amine)

**•** GDLN 850.4400

– Aquatic Plant Toxicity Test using Lemna gibba (Tier II)

**•** Please refer t o Registration Review

– Preliminary Problem Formulation for the Environmental Fate, Ecological Risk, and Endangered Species and Drinking Water Assessments for Tribenuron methyl

, dated March 15, 2011; and the EFED Response to Public Comments for Tribenuron m ethyl Preliminary Work Plan (PWP), dated July 29, 2011, located in the docket (EPA

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- 0626) , for a detailed discussion of t he risk assessment and data needs.6 Human Health Risk:

**•** The most recent human health risk assessment , including a drinking water assessment, for tribenuron methyl was completed in September 2009 for the registration of use on herbicide

- tolerant field corn and soybean to control broadleaf weeds.

**•** The Agency will requir e the following data for tribenuron methyl in order to cond uct a complete human health risk assessment:

o GDLN 870.3200

– Dermal Toxicity

o GDLN 870.3465

– 90

- Day Inhalation Toxicity

o GDLN 870.6200

– Acute and Subchronic Neurotoxicity Battery

o GDLN 870.7800

– Immunotoxicity

**•** After the required toxicology studies are s ubmitted and reviewed, EPA will re

- evaluate endpoints and safety/uncertainty factors for tribenuron methyl.

**•** During registratio n review, the Agency will update the dietary risk assessment with revised estimated drinking water concentrations

, changes in t oxicological endpoints, and incorporate any degradates that are determined to be of human toxicological

concern.

**•** There are no residential uses of tribenuron methyl. However, residential bystander
expos ures might occur as a result of aerial application an d off

- site transport (e.g., spray drift or volatilization). The Agency will consider the need for a bystander inhalation risk assessment for tribenuron methyl during registration review

.

**•** The Agency will revise the aggregate assessment to include changes in dietary exposure estimates and any residential bystander exposure estimates, if applicable.

**•** The Agency will conduct new occupational handler and post

- application assessments as necessary, based on updated doses, endpoints, and procedures for both derma l and inhalation endpoints.

**•** The Agency will modify tolerances as needed, and work to harmonize tolerance/MRLs where possible in key export markets during registration review.

**•** For more information

, please refer to Tribenuron methyl: Human Health Assessmen t Scoping Document in Support of Registration Review , March 2, 2011, located in the docket (EPA

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.7 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 sys temic toxicity. These studies include endpoint s 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 h azard 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 tribenuron methyl registration decision

, EPA reviewed these data and sele cted the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), tribenuron methyl is subject to the endocrine screening part of the Endocrine Disruptor Screening Pro gram (EDSP). Endocrine Disruptor Screening Program

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 end ocrine effects as the Administrator may designate.” The EDSP employs a two

- tiered approach to making the
statu torily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interac t 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 t he 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 ingred ients and 9 inert ingredients. Tribenuron methyl is not among the group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. Accordingly, as part of registration review, EPA will issue future EDSP orders/data call

- ins, re quiring the submission of EDSP screening assays for tribenuron methyl

. For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, please vis it our website: http://www.epa.gov/endo/

.8 Timeline:

EPA has created the following estimated timeline for the completion of the tribenuron methyl registration review.

Registration Review for Tribenuron methyl

– Projected Registration Review Timeline
Activities Estimated Date Opening the Docket Open Docket and Public Comment Period 2011

– March Close Public Comment 2011

– May Case Development Final Work Plan 2011

– August Issue DCI 2012

– April

– June Data Submission 2014

– April

– June Open Public Comment Period for Draft Risk Assessments 2015

– Oct.

– Dec. Close Public Comment Period 2016

– Jan.

– March Registration Review Decision Open Public Comment Period for Proposed Registration Review De cision 2016

– April

– June

Close Public Comment Period 2016

– July

– Sept. Registration Review Decision and Begin Post

- Decision Follow

- up 2017 Total (years) 6

Summary of Comments and Agency Responses

The tribenuron methyl registration review do cket was open for a 6 0

- day comment period beginning on March 30, 2011

. During the comment period, comments were submitted by E.I. DuPont Nemours & Co., Inc

. and the Federal Endangered Species Task Force

. The comments received do not change the risk asses sment, data needs, or the timeline detailed in the tribenuron methyl PWP . A general summary of these comments and the Agency’s response to
comments is provided below.

For a detailed description of the comments received and the Age ncy’s response to comm ents please refer to EFED Response to Public Comments for Tribenuron m ethyl Preliminary Work Plan (PWP)

, dated July 29, 2011, which is located in the tribenuron methyl docket (EPA

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OPP

- 2010

- 0626)

.
E.I. DuPont Nemours & Co., Inc. (DuPont)

Comment: DuPon t questioned the need for a non

- guideline terrestrial plant study for tribenuron
met hyl to evaluate the effects on see d production and viability at multiple stages of maturity

. The registrant cited a review of exist ing data in the open literature and two studies not yet submitted to the Agency to support its view that the data currently provided by guideline9 terrestrial non

- target plant studies evaluating effects on seedling plants is protective of potential reproductive effects.

Agency Response: The Ag ency has concerns that sulfonylurea (SU) herbicides may affect plant reproduction at rates lower than those that cause phytotoxic effects to vegetative vigor. Due to these concerns, the Agency is requesting plant reproduction studies for all SUs during

r e gistration r eview. While DuPont contends that recently conducted greenhouse and field studies for chlorsulfuron demonstrate that guideline vegetative vigor studies (850.4 1 50) are protective of reproduction endpoints, these studies ha ve not been submitted for Agency review at this time. The Agency will evaluate the se studies upon submission and determine the applicability of the data to other SU herbicides and test species . Until such time, the plant reproduction study for tribenuron methyl is still neede d

.

Comment: DuPont also questioned the need for ecotoxicological studies on triben uron methyl degradates, citing numerous studies which were conducted for its European Union (EU) registration. DuPont further stated that these studies indicate that the me tabolites are at least 2000 to 49000 times less toxic than the parent tribenuron methyl.

Agency Response: The Agency will consider the aquatic toxicity data conducted for the EU that DuPont recently submitted to the Agency

. If the submitted studies a re found to be acceptable and the metabolite data show a decrease in phytotoxicity to aquatic plants relative to the parent compound, then the toxicity data for terrestrial plants on those degradates would not be
necessary. However, until the reviews are completed, the data gaps noted in the PWP remain.

Federal Endangered Species Task Force (FESTF)

Comment : I n response to the PWP , specifically to the need for additional information to complete an assessment on federally

- listed threatened and endangered species that may be exposed to tribenuron methyl , FESTF stated that its data on endangered species proximity contained in the FESTF Information Management System (FESTF IMS) submissions (2004, 05, 07) to the Agency “fulfill the data requirements... and provi de the best available data necessary for the proximity analysis of tribenuron methyl use and listed species locations.” FESTF stated that the tribenuron methyl technical registrants D uP ont , Cheminova A/S, Gowan Company, and Nufarm Limited are current memb er s of FESTF and

, as such, are entitled to the FESTF data on federally

- listed threatened and endangered species. The technical registrants Arysta Lifescience North America and Rotam Limited are not currently eligible to rely on FEST F data.

Agency Respo nse: The Agency thanks FESTF for its comment and will consider this information at the time the risk assessments for tribenuron methyl are conducted.10 Next Steps

The Agency will require several ecological effects and human health studies through a data call

- in, which is expected to be issued in mid

- 2012. This new information will be used to conduct risk assessments for tribenuron methyl uses.Summary of Data Gaps

– Tribenuron methyl

The table below summarizes all data needs for tribenur on methyl in the Registration Review

– Preliminary Problem Formulation for the Environmental Fate, Ecological Risk, and Endangered Species and Drinking Water Assessments for Tribenuron methyl

, dated March 15, 2011

, and the Tribenuron methyl: Human Health As sessment Scoping Document in Support of Registration Review, dated March 2, 2011.

Guideline Number Data Requirement Test Material Study Duration

835.6100 Environmental Chemistry Methods and ILV for Soil T EP 24

835.6200 Aquatic Field Dissipation (i ncluding Environmental Chemistry Methods and ILV for Soil and Water) T EP 24

850.1025 Oyster Acute Toxicity Test (shell deposition) TGAI 12

850.1300 Invertebrate Life

- Cycle Toxicity Test (freshwater) TGAI, (parent & degradate s) 1 12

850.1400 Fish Early

- Life Stage Toxicity (saltwater) TGAI 12

850.2100 Avian Acute Oral Toxicity (passerine) 2 TGAI 12

850.4100 Seedling Emergence

, Tier II TEP, (parent & degradate s) 3 12

850.4150 Vegetative Vigor, Tier II TEP, ( d egradate s) 4 12

850.4400 Aquatic Plant Toxi city T est using Lemna spp. Tier II TEP, (parent & degradate s) 12
3

870.3200 21/28

- Day Dermal Toxicity TGAI 24
870.3465 90

- Day Inhalation Toxicity 5 TGAI 24

870.6200 Neurotoxicity Screening Battery (Acute and Subchronic) TGAI 24
870.7800 Immunotoxicity TGAI 12

NON

- GDLN Special Study for Non

- target Plant Reproductive Toxicity 2 TEP 24

1 The DCI will require this study for the parent tribenuron and the major degradates, triazine amine, saccharin, and sulfonamide

. 2 The DCI will require that a protocol be submitted for review and approval by the Agency prior to initiation of this study. 3 The DCI will require this study for the parent tribenuron methyl and the major degradates, o

- demethyl

- triazine amine, triazine amine, saccharin, and sulfonamide. 4 The DCI will require this study for the major degradates, triazine amine, saccharin, and sulfonamide

. 5 Based on expected durat ion of exposure, the DCI is expected to provide that registrants may conduct a 28

- Day inhalation toxicity study in lieu of a 90

- day study

.