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INTRODUCTION

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for the 

registration review of spirodiclofen. This work plan addresses public comments received concerning 

the Preliminary Work Plan (PWP), which was posted in the spirodiclofen registration review docket 

(EPA-HQ-OPP-2014-0262). Spirodiclofen is an insecticide/miticide in the tetronic and tetramic 

acid chemical class that acts by interfering with development in eggs, and nymphal and adult female 

growth stages (adult males are not affected). Products containing spirodiclofen are registered to 

control mites and San Jose scale on citrus, grapes, hops, pome fruit, stone fruit, tree nuts, tropical 

fruits (avocado, black sapote, canistel, mango, mamey sapote, papaya, sapodilla, star apple), and 

Christmas tree plantations There are no residential uses for spirodiclofen.

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 FIFRA 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 standard. The public phase of 

registration review begins when the initial docket is opened for each case. Information on this 

program is provided on the Agency’s website.

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The FWP begins with any updates 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 responses to those comments. This section is followed by registration review planned 

data needs, risk assessments expected to be conducted, and the projected registration review timeline

for spirodiclofen. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on spirodiclofen since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on the spirodiclofen PWP, which opened on March 20, 

2015 and closed on May 29, 2015 the Agency received three sets of public comments. Comments 

were submitted by the FIFRA Endangered Species Taskforce (FESTF), the Center for Biological 

Diversity (CBD) and Bayer CropScience (BCS). 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 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 made about the PWP nor all of the Agency’s 

responses. Summarized below are public comments that are of a broader regulatory nature. No 

comments resulted in changes to the anticipated registration review data needs, risk assessments or 

 1 http://www.epa.gov/oppsrrd1/registration_review/
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timeline. Public comments and EPA responses in their entirety are located in the docket, EPA-HQOPP-2014-0262. Summarized public comments and Agency responses related to the anticipated 

ecological risk assessment or data needs are in the Review of Public Response to Spirodiclofen Problem 

Formulation in the Registration Review Preliminary Work Plan, while those relevant to the anticipated 

human health risk assessment or data needs are in the Spirodiclofen: Response to Comments on the Human 

Health Scoping Document for Registration Review. Comments relevant to the pesticide’s use and chemical 

profile can be found in the Response to Public Comments from Bayer (registrant) on the BEAD Chemical 

Profiles for Spirodiclofen and Spiromesifen.

Comments submitted by FESTF in EPA-HQ-OPP-2014-0262-0008.

Comment: FESTF noted that BCS is member of the task force and is entitled to make use of the FESTF 

database on species proximity to use sites. 

Response: The Agency is aware of the data developed by FESTF and will use those data to evaluate 

risks to listed species, as appropriate.

Comments submitted by CBD in EPA-HQ-OPP-2014-0262-0009.

Comment: CBD’s comments focus on the EPA’s independent duty under the Endangered Species Act (ESA) to 

consult with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) on the 

registration review of spirodiclofen.

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 Academy of Sciences (NAS) report. EPA will address concerns specific to 

spirodiclofen’s effects on listed species in connection with the development of its registration review 

decision.

At this time, EPA has not fully developed its risk 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 Approaches for assessing risks to listed species from 

pesticides. The Interim Approaches were developed jointly by the Agencies in response to the 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, available at http://www.nap.edu/catalog.php?record_id=18344, 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 obligations under 

the ESA and FIFRA. 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 Pesticide 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 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 the National 

Academy of Sciences April 2013 Report,” dated November 1, 2013, available 

at http://www.epa.gov/espp/2013/nas.html
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Comments submitted by BCS in EPA-HQ-OPP-2014-0262-0010

Comment: Bayer CropScience provided comments intended to address requests, errors, and inconsistencies found in 

the following EPA documents: 1) Preliminary Work Plan, 2) Usage Overview – Label Review, BEAD Chemical 

Profile, Screening Level usage Analysis and Tier I Review of Human Incidents 3) Environmental Safety - Problem 

Formulation for the Ecological Risk Assessment and Drinking Water Assessment 4) Human Safety - Human 

Health Assessment Scoping Document

Response: The comments presented by BCS provide clarifications and consistency to the documents 

listed above. The response to comments documents from the Environmental Fate and Effects 

Division (EFED), the Health Effects Division (HED) and the Biological and Economical Analysis 

Division (BEAD) acknowledge general agreement with the comments of BCS on use sites and 

production practices and address BCS’s comments on the calculation of the formation/decline 

constants for modeling toxic residues of pesticides in the environment.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for spirodiclofen based on the Registration Review –

Problem Formulation for the Ecological Risk Assessment and Drinking Water Exposure Assessment to be 

Conducted for Spirodiclofen and the Spirodiclofen. Human Health Assessment Scoping Document in Support of 

Registration Review.

Table 1: Planned Data Needs for the Spirodiclofen Registration Review

Guideline 

Number2 Study Title Test 

Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

Anticipated Data Needs for the Parent Spirodiclofen

835.4200 Anaerobic Soil Metabolism TGAI 24

835.4400 Anaerobic Aquatic Metabolism3 TGAI 24

850.1350 Aquatic Invertebrate Life Cycle (Saltwater) TGAI 12

850.1735 Whole Sediment: Acute Toxicity Freshwater 

Invertebrates with Chironomus dilutus4, 5 TGAI 12

850.1735 Whole Sediment: Acute Toxicity Freshwater 

Invertebrates with Hyalella azteca6, 7 TGAI 12

850.1740 Whole Sediment: Acute Toxicity Marine 

Invertebrates with Leptocheirus plumulosus7, 6 TGAI 12

 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 Availability” 77 FR 38282, June 27, 2012. 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0154-0028 3

 Testing on one additional water/sediment system is needed 4 Also known as “Whole Sediment: Subchronic Freshwater Invertebrates,” as per EFED Guidance Document 

Entitled “Toxicity Testing and Ecological Risk Assessment Guidance for Benthic Invertebrates.” April 2014 5 A 10-day study is anticipated to be requested. 6 Also known as “Whole Sediment: Subchronic Marine Invertebrates,” as per EFED Guidance Document Entitled 

“Toxicity Testing and Ecological Risk Assessment Guidance for Benthic Invertebrates.” April 2014.
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Table 1: Planned Data Needs for the Spirodiclofen Registration Review

Guideline 

Number2 Study Title Test 

Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

850.2100 Avian Oral Toxicity (Passerine Species)7 TGAI 12

850.3040 Field Testing for Pollinators TEP 24

850.6100

Environmental Chemistry Methods and 

Associated Independent Laboratory 

Validations for Water

TGAI 12

Non-Guideline

(OECD 237)

Honey bee larvae acute oral toxicity8

TGAI 12

Non-Guideline Honey Bee Adult Chronic Oral Toxicity TGAI 12

Non-Guideline Honey Bee Larvae Chronic Oral Toxicity TGAI 12

Non-Guideline Residues in pollen and nectar/field residue 

analysis TEP 24

Non-Guideline Semi-Field testing for Pollinators (Tunnel or 

Colony Feeding Studies) TEP 24

Spirodiclofen Degradates

850.6100

Environmental Chemistry Methods and 

Associated Independent Laboratory 

Validations for Water 

Degradates9 12

TGAI = technical grade active ingredient; TEP = typical end-use product;

RISK 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 spirodiclofen. For human health, EPA 

will conduct revised dietary and occupational risk assessments during registration review. If 

toxicological endpoints or points of departure are revised based on the data that are required for 

registration review, they will be considered in the new assessments, as well as any changes to the

standard operating procedures or default exposure assumptions.

Table 2 below summarizes the planned registration review risk assessments based on the EFED 

Problem Formulation and HED Scoping Document; the planned assessments have not changed 

from what was included in the PWP.

 7 A protocol does not need to be submitted for Agency approval prior to study initiation provided that the study 

adheres to the parameters outlined in the guidance available at: 

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/terrestrial_biology_tech_team/passerine_

ocspp850_2100_avian_oral_tox.pdf

8 Depending on the design of the “Honey Bee Larvae Chronic Oral Toxicity,” study, a 72-hour LD50 value may be 

derived. If this endpoint is able to be derived, then it would obviate the anticipated need for the (OECD TG 237) 

Honey Bee Larvae Acute Oral Toxicity (Tier 1) study 9 Degradates of concern spirodiclofen-enol (BAJ 2740-enol), spirodiclofen-dihydroxy (BAJ 2740-dihydroxy), and 

spirodiclofen-ketohydroxy (BAJ 2740-ketohydroxy).
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Table 2: Planned Risk Assessments for the Spirodiclofen 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 

Yes Spirodiclofen will be considered the stressor of concern 

for the risk assessment. Spirodiclofen and degradates 

will be included in the drinking water exposure 

assessment.

Incidents Will check 

for updates

For a discussion of the sole reported ecological incident 

for spirodiclofen, see page 31 of the Problem 

Formulation.

Human Health

Dietary

Food Yes May be required to reflect the most recent dietaryexposure models and revised estimated drinking water 

concentrations (EDWCs). 

Drinking water Yes May be revised to reflect the most recent dietaryexposure models (specifically, use of PRZM-GW).

Occupational

Handlers (mixers, loaders, 

applicators)

Yes Updated inhalation assessments may be conducted to 

reflect maximum application rates, using current 

occupational exposure policies and updated inhalation 

toxicological points of departure.

Post-application Yes A post-application inhalation assessment may be 

conducted to reflect maximum application rates, the 

highest exposure post-application activities, current 

exposure policies, and updated inhalation toxicological 

points of departure.

Residential

Handlers No There are no residential uses of spirodiclofen. 

Post-application Yes The need for spray drift and volatilization risk 

assessments will be examined.

Other

Aggregate Yes Evaluates the combined risk from dietary and residential 

exposures and may be required to reflect potentially 

revised EDWCs.

Cumulative No Spirodiclofen has not been identified as a member of a 

cumulative group that shares a common mechanism of 

toxicity, and spirodiclofen does not appear to produce a 

toxic metabolite produced by other substances.

Tolerances Yes Decisions concerning harmonization of the U.S. 

tolerance values with either the Canadian and/or Codex 

MRLs will be made as part of Registration Review.

Incidents Will check 

for updates

For a discussion of the small number of reported human 

incidents for spirodiclofen, see page 10 of the Scoping 

Document and the Spirodiclofen: Tier I Review of Human 

Incidents.
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TIMELINE

EPA has created the following estimated timeline for the completion of the spirodiclofen

registration review in Table 3 below. The projected timeline has been adjusted only to reflect a 

change in the timeframe for submitting data on “Residues in pollen and nectar/field residue 

analysis” from 36 months after receipt of the DCI to 24 months after receipt of the DCI. 

Table 3: Registration Review for Spirodiclofen – Projected Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period 2015 March -Completed

Close Public Comment 2015 May- Completed

Case Development

Final Work Plan 2015 August- Completed

Issue DCI 2015- October- December

Data Submission 2017- October-December

60-day Public Comment Period for Draft Risk Assessments10 2019- April-June

Registration Review Decision

60-day Public Comment Period for Proposed Registration Review 

Decision 

2020- January-March

Registration Review Decision and Begin Post-Decision Follow-up 2020

Total (years) 5

NEXT STEPS

As noted previously, the Agency plans to require several environmental fate and ecological effects, 

studies for spirodiclofen through a Data Call-In Notice, expected to be issued in OctoberDecember 2015. 

 10 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.