I NTRODUCTION

This is the Environm ental Protection Agency’s (EPA or the Agency ) Final Work Plan (FWP) for the registration review of oxadiazon . This work plan addresses public comm ents received concerning the Preliminary Work Plan (PWP) , which was posted in the oxadiazon registration review docket (EPA

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- 0782 ). Oxadiazon is a selective herbicide that is registered for use as pre

- and early post

- emergence treatments for the control of many annual broadleaf and grass weeds. It was first registered in the U.S. in 1978. Today, major use sites of oxadiazon are
establi shed or newly established bermudagrass, perennial ryegrass, fescue turf, and various ornamentals including landscape ornamental beds. There are no registered food or feed uses for
oxadiazon.

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 F IFRA standard for registration. Changes in science, public policy, and pesticide use practices 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 the statutory standar d. The public phase of registration review begins when the initial docket is opened for each case.
Informatio n on this program is provided on the Agency’s website

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The FWP begins with any upd ates since the PWP was issued. Next is a summary of substantive

comments received during the public comment period 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 response s to th o se comments

. This section is follow ed by registration
review planned data needs, risk assessments expected to be conducted , and the projected registration review timeline for oxadiazon

. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

In the PWP, the Agency identified Guideline Number (GLN) 875.2100, which includes dislodgeable foliar residue (DFR) and turf transferable residue (TTR) studies, as an anticipated data requirement for the registration review of oxadiazon. Since the PWP, the Agency received

commen ts from Bayer Environmental Sciences (Bayer) which provided information about existing TTR data for liqu id formulations of oxadiazon as well as estimates of post application exposure for granular formulations using the default transfer coefficients specifi ed in the Agency’s 2012 Residential SOP

. As a result, the Agency has determined that a new TTR s tudy is
not needed . Therefore, in this FWP, the TTR portion of GLN 875.2100 is no longer listed as a
data need. However, t he DFR portion of GLN 875.2100 is stil l required

.

T he following two data requ irements from GDCI

- 109001

- 24733 are no longer listed as outstanding : seedling emergence (GLN 850.4100) and vegetative vigor (GLN 850.4150)

. EPA has received acceptable data to fulfi l l these data requirements.

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

2In addition , the Agency has added a honey bee toxicity of residues on foliage study ( GLN
850.3030 ) to the list of data needs for the registration review of oxadiazon

, and has also revised
the study time frame for the full

- field testing for pollinators (GLN 850 .3040) from 36 months to
24 months , based on the most up

- to

- date pollinator implementation guidance.

Finally, as noted in the PWP, the Agency has revisited the need for an aggregate risk assessment during the registration review of oxadiazon. The table of planned risk assessments in the FWP now indicates that EPA plans to conduct an aggregate assessment that will consider the combined exposure from drinking water and residential sources.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60

- day public c omment period on the oxadiazon Preliminary Work Plan , which opened on December 19, 2014 and closed on February 17, 2015, the Agency received public

comments from three stakeholders

. Comments were submitted by the Center for Biological Diversity (CBD), FIFRA Endangered Species Task Force (FESTF), and Bayer Environmental Science (Bayer )

. The comments do not address the timeline described in the PWP, but they do
add ress the planned human health risk asse ssments and ecological and human health data requirements. In the PWP, EPA also solicited comments on the specific topics of environmental justice, water quality concerns

, and trade irritants, but no comments or information were received
on those issues.

This section does not capture every comment m ade about the PWP nor all of the Agency’s

responses. Summarized below are public comments that resulted in changes to the anticipated registration review data needs, risk assessments, or are o f a broader regulatory nature. P ublic

comments in their entirety are located in the docket, EPA

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. Summarized public comments and Agency responses related to the anticipated ecological data needs are in the

EFED memo titled EPA Response to Comments Related to the “Oxadiazon Preliminary Work Plan: Registr ation Review” while those relevant to the anticipated human health risk assessment
and data needs are in the HED memo titled Oxadiazon. HED’s Response to Public Comments Received on the Preliminary Work Plan for Registration Review.

Comments submitted b y CBD in EPA

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1. Comment : The Center for Biological Diversity’s (CBD) comm ents focus on the EPA’s duty

to consult with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) on the registration review of oxadiazon in accordance with the Endangered Species Act (ESA). The CBD comments mention various aspects of the risk assessment process, including use of the best available data to develop endangered species risk assessments, and evaluation of ef fects on endangered and threatened species and their designated critical habitat. CBD also expresses concern regarding the rigor of the Agency’s preliminary determinations re garding the effects of oxadiazon on endangered and threatened (listed) species and their designated critical habitat for the oxadiazon registration review.

Response : EPA has reviewed the comments from CBD on the registration review docket opening for oxadiazon and plans to address many of the concerns raised by CBD as part of the implementation plan for assessing the risks of pesticides to listed species based on the

3recommendations of the April 2013 National Aca demy of Sciences (NAS) report. EPA will
add ress concerns specific to oxadiazon in connection with the development of its final registration review decision for oxadiazon.

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 pesticide s. 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 be tween the EPA and the Services. The NAS report outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that EPA and the Services must conduct in connection with their oblig ations
under the ESA and FIFRA.

The joint Interim Approach es were released prior to a stakeholder works hop held on November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the
December 2013 Pesticide Program Dialogue Committee (PPDC) and State

- FIFRA Issues Research and Evaluation Group ( S FIREG) meetings . The agencies also held stakeholder workshop s in April 2014 and October 2014 , allowing additional opportunities for
stakeholders to comm ent on the Interim Approaches. Additional workshops are planned to
enhance stakeholder involvement. As p art 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 Inter im Approaches are contained in the white paper “Interim Approaches for National

- Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Rep ort,” 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, the ecol ogical problem formulation supporting this Final Work
Plan for oxadiazon does not describe the specific ESA analysis

, includ ing effects determinations for specific listed species or designated critical habitat , to be conducted during registration review

. I n the ecological problem fo rmulation document for oxadiazon

, EPA described the screening

- level risk assessment to determine th e potential effects of
oxadiazon on all taxa of non

- target wildlife and plants , which will assume that listed species
and their designated critical habitats may be present in the vicinity of the applicati on of
oxadiazon

. This screening

- level assessment will allow EPA to focus its future evaluations on the types of species where the potential for effects exists once the scientific m ethods being developed by the agencies have been fully vetted. While the agencies continue to develop a common method for ESA analysis, the planned screening

- level risk assessment for the registration review of oxadiazon will describe the level of ESA anal ysis completed for this particular registration review case. Once the agencies have fully developed and implemented the scientific methods necessary to complete risk assessments for endangered and threatened (listed) species and their designated critical h abitats, these methods will be app lied to

s ubsequent analyses for oxadiazon as part of completing this registration review.

4Comments submitted by FESTF in EPA

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2. Comment: “ The technical registrants, as identified on the fact sh eet included in the Registration Review work plan, are Bayer Environmental Science, which is a subsidiary of Bayer CropScience and Nufarm Limited, which is a subsidiary of Nufarm Americas, Inc., which are FESTF members and are entitled to rely on FESTF data .”

Response: The Agency thanks FESTF for the comment and will consider this information during registration review.

Comments submitted by Bayer in EPA

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3. Comment: Bay er submitted comments regarding the anticipated HED data requirements for registration review and submitted information on the intended use patterns and application parameters of oxadiazon

.

Response: For a detailed response to these comments, please refer to the HED memo titled Oxadiazon. HED’s Response to Public Comments Received on the Preliminary Work Plan for Registration Review . Note, as a result of Bayer’s comments, EPA has changed one of the anticipated HED data requirements . In the PWP, the Agency identified GLN 875.2100, which includes dislodgeable foliar residue (DFR) and turf transferable residue (TTR) studies,

as an anticipated data requirement for the registration review of oxadiazon. As detailed in the section of this document “Updates Since the PWP was Issued

, ” the Agency received
comments from Bayer which result ed in the Agency revisiting the need for new TTR data

. T he Agency agrees with Bayer that the TTR portion of GLN 875.2100 is no longer needed ; h owever, the DFR portion of GLN 875.2100 is still required

.

4. Comment: Bayer submitted com ments regarding the anticipated EFED data requirements for registration review as well as information regarding oxadiazon degradates, use patterns, and application parameters relevant to the planned ecological risk assessments

.

Response : For a detailed response to these comments, please refer to the EFED memo titled EPA Response to Comments Related to the “Oxadiazon Preliminary Work Plan: Registration

Review

. ” Note , in the FWP, t he following two data requ irements from GDCI

- 109001

- 24733

are no longer listed as outstanding: seedling emergence (GLN 850.4100) and vegetative vigor (GLN 850.4150). Previously submitted data has been reviewed and found Acceptable by the EPA.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for oxadiazon based on the EFED Registration Review Problem Formulation for Oxadiazon

, the Oxadiazon

. Human Health Scoping Document in Support of Registration Review

, the EFED memo titled EPA Response to Comments Related to the “Oxadiazon Preliminary Work Plan: Registration Review” and the

HED memo titled Oxadiazon. HED’s Response to Public Comments Received on the Preliminary Work Plan for Registration Review

. The table has been updated since the PWP to reflect public comments which resulted in changes to the data needs

.

5Table 1: Planned D ata Needs for the Oxadiazon Registration Review

Guideline

Number 2 Study Title 2 Test Material Estimated

Timeframe
(Months from receipt of DCI)
or Status

835.4100 Aerobic soil metabolism TGAI 24

850.2100 Avian oral toxicity (passerine species) TGAI 12

850.4550 Cyanobacteria toxicity T GAI 12

850.6100 Terrestrial field dissipation study (for turf) TEP 24

850.6100 Environmental chemistry methods and associated independent laboratory v alidation s for the parent, oxadiazon, and three of its metabolites (methoxy, phenolic, and carboxylic) in soil/sediment and water TGAI and three
metabolites 12

Non

- GDLN Special Study Honey bee adult acute oral toxicity (OECD 213) TGAI 1 2

Non

- GDLN Special Study Ho ney bee larvae acute oral toxicity (OECD 237) TGAI 1 2

Non

- GDLN Special Study Honey bee adult chronic oral toxicity TGAI 1 2

Non

- GDLN Special Study Honey bee larvae chronic oral toxicity TGAI 1 2

Non

- GDLN Special Study Field trial of residues in pollen and nectar 3 TEP 24

Non

- GDLN Special Study Semi

- field testing for pollinators (OECD 75) 3 TEP 24

850.3030 Honey bee toxicity of residues on foliage 3 TEP 12

850.3040 Full

- f ield testing for pollinators 3 TEP 24

870.3465 28

- day inhalation toxicity TGAI 12

875.2100 Dislodgeable foliar residue TGAI 12
Outstanding Data Requirements from GDCI

- 109001

- 24733 4

835.4300 Aerobic aquatic metabolism (address un

identified/un

- extracted residue) TGAI Supplemental (MRID 46594701)

2 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 A vailability” 77 FR 38282, June 27, 2012. http://www.regulations.gov/#!documentDetail;D=EPA

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3 The need for this anticipated data requirement is contingent on results of the tier 1 bee studies (including acute oral

toxicity to adult honey bees, acute oral toxicity to larval honey bees, chronic oral toxicity to adult honey bees, and chronic oral toxicity to larval honey bees).

4 The studies listed in this section were previously required through a generic data call

- in issued in November 2004

and are still outstanding , or in review . These studies will not be included in the anticipated Registration Review

DCI because they are already required throug h the earlier DCI.

6Table 1: Planned D ata Needs for the Oxadiazon Registration Review

Guideline

Number 2 Study Title 2 Test Material Estimated

Timeframe
(Months from receipt of DCI)
or Status

850.1350 Mysid chronic toxicity test

– life

- cycle toxicity with Mysids ( America mysis

, formerly Mysidopsis bahia ) TGAI In review (MRID 46473304)

850.1400 Freshwater fish early

- life stage (raw data for the previously submitted study with rainbow trout) TGAI In review (MRID 41811601)

850.1735 Whole sediment acute toxicity freshwater invertebrates: toxicity to freshwater amphipods ( Hyalella azteca ) during a 10

- day sediment exposure TGAI In review (MRID 46473303)

850.1740 Whole sediment acute toxicity freshwater invertebrates: toxicity to midge ( Chironomus riparius ) during a 10

- day sediment exposure TGAI In review (MRID 46487301)

Non

- GDLN Special Study Freshwater fish early life

- stage toxicity test with fathead minnow ( P im eph ales promelas ) under high light conditions TGAI In review (MRID
4875910 1)
TGAI = technical grade active ingredient; TEP = typical end

- use product

7RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency will conduct a comprehensive ecological risk assessment, including an endangered species assessment, for all uses of oxadiazon. For human health, EPA will conduct revised dietary (drinking water only), residential, an d occupational risk assessments during registration review; EPA also plans to conduct an aggregate (combined drinking water and residential) assessment based on currently available information and science/risk assessment policies. If toxicological endpoint s or points of departure are revised based on the data that are required to be submitted for registration review, the revised endpoints or points of departure will be considered in the new assessments, as will any changes to the standard operating p rocedur es or default exposure assumptions

.

Table 2 below summarizes the planned registration review risk assessments based on the EFED
Problem Formulation and HED Scoping Document . T he table has been updated since the PWP to indicate that EPA plans to conduct an aggregate assessment. The other planned assessments have not changed from what was included in the PWP

.

8Table 2: Planned Risk Assessments for the Oxadiazon Registration Review

Type of Risk Assessment Conduct ? Notes

Eco logical and Environmental Fate Comprehensive ecological (species to be assessed include terrestrial and aquatic organisms ), including endangered species Yes EPA anticipates conducting an updated comprehensive ecological risk assessment during registration review. The new assessment wil l incorporate the most up

- to

- date modeling methodologies, updated toxicological endpoints, and data submitted under the anticipated registration
review data call

- in.

Incidents Will check for updates For a discussion of reported ecological incidents for
oxadiazon , see page 14 of the Problem Formulation.

Human Health Dietary

Food No There are no registered food uses for oxadiazon. EPA does not anticipate conducting an updated dietary assessment for registration review unless there are significant changes to the drinking water estimated concentrations or if there are significant changes to the points of departure, uncertainty factors, or safety
factors. Drinking water Yes EPA anticipates conducting an updated drinking water assessment during regist ration review to incorporate updated estimated drinking water
concentrations. Occupational Handlers (m ixer s, loader s, applicators ) Yes The most recent occupational exposure assessment
was conducted for the 2007 human health risk

assessment. EPA anticipates conducting an updated occupational handler assessment during registration
review.

Post

- application Yes The most recent occupational exposure assessment
was conducted for the 2007 human health risk assessment. EPA anticipates conducting an upda ted occupational post

- application assessment during registration review.

Residential

9Handlers Yes A residential handler assessment has not been performed. Based on information submitted during the PWP comment period by Bayer confirming their
intent to allow use of oxadiazon products on residential property, EPA plans to conduct a residential handler risk assessment for turn/lawn use
of oxadiazon during registration review.

In the 2007 human health assessment for ornamentals and landscape use, it was as sumed that there would be no residential handler exposure since the product could only be applied by professional landscape personnel (in accordance with the label). However, since the oxadiazon labels do not identify the end

- use products as restricted use , a residential handler exposure assessment is now required to be protective of potential homeowners who apply oxadiazon to
ornamentals.

Post

- application Yes The most recent residential post

- application exposure
assessment was conducted for the 2007 human health risk assessment. EPA anticipates conducting an updated residential post

- application assessment during registration review.

Other Aggregate Yes An aggregate assessment e valuates the combined risk from dietary and residential exposures. T he Agency anticipates conducting an aggregate assessment that
will consider the combined exposure from drinking
water and residential sources.

Cumulative No Not applicable; oxadiazon has not been identified as a member of a cumulative group that shares a com mon mechanism of toxicity.

Tolerances No Not applicable; there are no established tolerances for
oxadiazon.

Incidents Will check for updates For a discussion of reported human incidents for oxadiazon, see page 15 of the Scoping Document and
the Oxadiazon: Tier 1 Review of Human Incidents

.

TIMELINE

EPA has created the following estimated timeline for the completion of the oxadiazon registration review in Table 3 below

. The projected timeline has changed to reflect the revised study duration for the full

- field testing for pollinator s (GLN 850.3040)

.

10Table 3: Oxadiazon Projected Registration Review Timeline
Activity Estimated Date Opening the D ocket Open Docket and 60

- day Public Comment Period Dec. 2014

– Completed

Close Public Comment Period Feb. 2015

– Completed Case Development

Issue Final Work Plan May 2015

– Completed

Issue DCI 2015 July

– Sept.

Data Submission 201 7 July

– Sept.

60

- day Public Comment Period for Draft Risk Assessments 5 20 19 Jan.

- March Registration Review Decision

60

- day Public Comment Period for Proposed Registration Review

D ecision 20 19 Oct.

– Dec.

Issue Registration Review D ecision and Begin P ost

- D ecision F ollow

up 202 0

Total ( years ) 6

NEXT STEPS

As noted previously, the Agency plans to require several environmental fate, ecological effects,
and human health studies for oxadiazon t hrough a D ata C all

- I n Notice , expected to be issued in
mid

- to

- late 2015

.

5 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 6 0 calendar day public comment period generally for draft risk assessments.

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