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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 spiromesifen. This work plan addresses public comments received concerning 

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

(EPA-HQ-OPP-2014-0263). Spiromesifen is a tetronic acid insecticide/miticide and is reported to 

act through the inhibition of lipid biosynthesis. Spiromesifen works on all developmental stages of 

mites. However, mite juvenile stages are more susceptible than adults. Products containing this 

insecticide/miticide are registered for use to control a broad spectrum of mites and whiteflies.

Spiromesifen is registered for use on the following agricultural crops: low growing berries, tuberous 

and corm vegetables, leafy greens, fruiting vegetables, brassica vegetables, celery, com, cotton, and 

cucurbits. The non-agricultural use for spiromesifen is on ornamentals.

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 spiromesifen. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on spiromesifen since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on the spiromesifen Preliminary Work Plan, which 

opened on March 30, 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 

 1 http://www.epa.gov/oppsrrd1/registration_review/
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comments resulted in changes to the anticipated registration review data needs, risk assessments or 

timeline. Public comments and EPA responses in their entirety are located in the docket, EPA-HQOPP-2014-0263. Summarized public comments and Agency responses related to the anticipated 

ecological risk assessment or data needs are in the Response to the Initial 60-Day Public Comment 

on: Registration Review: Draft Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, 

and Human Health Drinking Water Exposure Assessments for Spiromesifen, while those relevant to the 

anticipated human health risk assessment or data needs are in the Spiromesifen; Response to comments 

from Bayer Crop Science regarding HED’s most recent Human Health Registration Review Scoping Document. 

Comment relevant to the 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-2014-0263-0010

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-2014-0263-0011

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 spiromesifen.

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 

spiromesifen’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 
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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.

Comments submitted by BCS in EPA-HQ-OPP-2014-0263-0012

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

the following EPA documents: 1) Preliminary Work Plan 2) Label Review, BEAD Chemical Profile, Screening 

Level usage Analysis 3) Problem Formulation for the Ecological Risk Assessment and the Drinking Water -

Exposure Assessment 4) Human Health Assessment Scoping Document and Tier I Review of Human Incidents 

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 usage, formulation 

type, and use parameters. They also 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 spiromesifen based on the Registration Review: 

Draft Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Human Health 

Drinking Water Exposure Assessments for Spiromesifen and Spiromesifen. Human Health Assessment Scoping 

Document in Support of Registration Review. The planned data needs have not changed from what was 

included in the PWP. 

Table 1: Planned Data Needs for the Spiromesifen Registration Review

Guideline 

Number2 Study Title Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

850.1400 Fish early-life stage toxicity (saltwater) -

Sheepshead minnow (Cyprinodon variegatus) TGAI 12

850.4500

Algal Toxicity - freshwater diatom (Navicula 

pelliculosa) and marine diatom (Skeletonema 

costatum)

TGAI 12

850.4550 Cyanobacteria (Anabaena flos-aquae) toxicity TGAI 12

850.6100 Environmental chemistry methods and 

associated independent laboratory validations in 

soil and water

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
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Table 1: Planned Data Needs for the Spiromesifen Registration Review

Guideline 

Number2 Study Title Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

Non-GLN Whole Sediment: 42-day chronic toxicity test to 

freshwater invertebrate (Hyalella azteca)3 TGAI 24

Non-GLN

Whole Sediment: 28-day chronic toxicity test to 

estuarine/marine invertebrate (Leptocheirus 

plumulosus)3

TGAI 24

850.3040 Field Testing for pollinators4 TEP 24

NonGuideline

(OECD 237)

Honey bee larvae acute oral toxicity5

TGAI 12

NonGuideline Honey Bee Adult Chronic Oral Toxicity TGAI 12

NonGuideline Honey Bee Larvae Chronic Oral Toxicity TGAI 12

NonGuidelineSemi-Field testing for Pollinators (Tunnel or 

Colony Feeding Studies)6 TEP 24

NonGuidelineResidues in pollen and nectar/field residue 

analysis TEP 24

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 spiromesifen. For human health, EPA 

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

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.

 3 The anticipated Data Call-In Notice will provide that a tiered testing approach may be considered for chronic sediment 

toxicity testing. Under this approach, testing would first be conducted using the sub-chronic (10-day) sediment toxicity 

test guidelines (OSCPP 850.1735 and 850.1740). Pending comparison of estimated environmental concentrations in 

sediment and pore water with results from the 10-day study, the Agency would determine the need for one or more 

chronic sediment toxicity studies. 

4 Data requirement is dependent on a re-review of the submitted field studies with spiromesifen. 5 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 Honey Bee Larvae 

Acute Oral Toxicity study (OECD TG 237) (Tier 1). 6 The registrant has the option to conduct either a tunnel or colony feeding semi-field (Tier II) study and should consult 

with the Agency on protocol design prior to study initiation.
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Table 2: Planned Risk Assessments for the Spiromesifen 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

Incidents Will check for 

updates

For a discussion of reported ecological incidents for 

spiromesifen, see page 16 of the Problem Formulation.

Human Health

Dietary

Food Yes A revised dietary exposure analysis may be required to 

reflect the most recent dietary exposure models.

Drinking water Yes A revised dietary exposure analysis may be required to 

reflect potential revised EDWCs-specifically, 

concentrations derived through use of PRZM-GW.

Occupational

Handlers (mixers, loaders, 

applicators)

Yes Updated occupational handler and post-application

assessments may be conducted to reflect all currently 

registered uses and maximum application rates, using 

current policies.

Post-application Yes

Residential

Handlers Yes

Post-application No Post-application dermal exposure is anticipated, but will 

not quantitatively assessed because no hazard was 

identified for the dermal route.

Bystander exposure to drift 

and volatilization

Yes The need for spray drift and volatilization risk 

assessments for spiromesifen will be examined during 

registration review.

Other

Aggregate Yes Evaluates the combined risk from dietary and 

residential exposures. A new aggregate assessment may 

be required during registration review if a revised 

dietary exposure analysis is required.

Cumulative No EPA has not made a common mechanism of toxicity 

finding for spiromesifen and any other substances; 

spiromesifen does not appear to produce a toxic 

metabolite produced by other substances.

Tolerances Yes Harmonization of tolerances/MRLs will be considered 

during Registration Review.

Incidents Will check for 

updates

For a discussion of reported human incidents for 

spiromesifen, see page 10 of the Scoping Document 

and Spiromesifen: Tier I Review of Human Incidents.
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TIMELINE

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

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 Spiromesifen – 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 Assessments7 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, ecological effects, and 

human health studies for spiromesifen through a Data Call-In Notice, expected to be issued in 

October-December of 2015. 

 7 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.