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Hexaflumuron FINAL WORK PLAN 

Introduction:

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

review of hexaflumuron. This work plan includes the expected registration review timeline. The 

work plan also addresses public comments received concerning the Preliminary Work Plan

(PWP) in the Summary Document, which was posted in the hexaflumuron registration review 

docket (EPA-HQ-OPP-2009-0568), and any other comments concerning the initial docket 

postings. The Summary Document provided information on what EPA knows about the 

pesticide and what additional risk analyses and data or information the Agency believes are 

needed to make a registration review decision. 

The Agency is implementing the new registration review program and will review each 

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

Hexaflumuron is a benzoyl-phenylurea termiticide registered for use to control all economically 

important species of termites. It is registered for use in above- and below-ground termite bait 

station systems in food and nonfood areas. Treatment sites may include interior and exterior 

surfaces of buildings and crawl spaces, fences, utility poles, decking, landscape decorations, 

trees, and other features which could be damaged by termite foraging and feeding activity. 

Hexaflumuron is approved for use in indoor residences. While it is not a restricted use product, 

hexaflumuron is sold in conjunction with a service provided by pest-control operators licensed 

by the state to apply termiticides. As hexaflumuron was first registered in 1994, it was not 

subject to the reregistration process as required by FIFRA. 

Comments Received on Preliminary Work Plan:

The Agency received two comments on the Hexaflumuron Preliminary Work Plan during the 60 

day comment period that was open September 23, 2009 to November 23, 2009. The FIFRA 

Endangered Species Task Force (FESTF) commented on data compensation matters. Dow 

AgroScience (DAS), the technical registrant, responded to information requests specified in the 

PWP, provided error corrections, and commented on the anticipated ecological fate and effects 

data needs. Response to comments relating to human health comments on the hexaflumuron 

PWP are addressed in a separate document entitled Hexaflumuron Public Comment Regarding 

the Health Effects Division’s Human-Health Assessment Scoping Document in Support of 

Registration Review of 12-AUG-2009 (D362321). Response to comments relevant to the 

required ecological risk assessment for hexaflumuron are addressed in a separate document 

entitled EFED Response to Comments on the Problem Formulation for Hexaflumuron

(D362322). An overview of comments is presented in the “Summary of Comments and Agency 

Responses” section of this document. A more detailed description of the comments received and 
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the Agency’s response to these comments is available in the separate response memoranda from 

the Agency’s Environmental Fate and Effects Division (EFED) and Health Effects Division 

(HED) located in the hexaflumuron docket (Docket ID EPA-HQ-OPP-2009-0568). 

Risk Assessment and Data Needs:

Environmental Fate and Ecological Risk: 

• The Agency has not conducted a risk assessment that supports a complete endangered 

species determination. The ecological risk assessment planned during registration review 

will allow the Agency to determine whether hexaflumuron 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. 

• Please refer to the February 17, 2010 document, EFED Response to Comments on the 

Problem Formulation for Hexaflumuron (D362322) in the registration review docket 

(Docket ID EPA-HQ-OPP-2009-0568), for a detailed discussion of the anticipated 

ecological risk assessment. 

• Based upon comment received on the PWP, the Agency has decided the following studies 

will not be needed to support hexaflumuron registration review: 

o (GLN 835.1230 and 835.1240) Leaching and Adsorption/Desorption Mobility Study 

o (GLN 835.4100) Aerobic Soil Metabolism Study 

o (GLN 835.4200) Anaerobic Soil Metabolism Study 

• Based on the Agency’s review of the available ecotoxicity and environmental fate data for 

hexaflumuron, the Agency will issue a data call-in for the following data to support an 

ecological risk assessment for hexaflumuron registration review: 

o (GLN 850.2300) Avian Reproduction Tests (waterfowl and upland game species) 

o (Special Study) Acute Oral Toxicity to Honey Bees 

o (GLN 850.4100) Seedling Emergence (Tier I) 

o (GLN 850.3040) Field Test for Pollinators. The Agency notes that these data may be 

required in the absence of information indicating exposure to pollinators is negligible. 

Human Health Risk 

• Because of the low toxicity of hexaflumuron and the low-exposure scenarios expected from 

hexaflumuron products, a human health risk assessment has not been previously conducted. 

• Given the current uses, the Agency does not anticipate conducting a human health risk 

assessment for hexaflumuron to support registration review. However, if in the future new 

uses or use patterns emerge, human health risk assessments that examine the dietary, 

residential, aggregate, or occupational risks of hexaflumuron may be required. 

• Based on the Agency’s review of available human health toxicity and exposure data for 
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hexaflumuron, no additional data are expected to be required to support registration review. 

• Please refer to Hexaflumuron Human-Health Assessment Scoping Document in Support of 

Registration Review (D362321), located in Docket Number EPA-HQ-OPP-2009-0568 at 

www.regulations.gov for a detailed discussion of the Agency’s human health risk 

assessment needs for hexaflumuron. 

Other Data Needs

• (GLN 830.7050) UV/Visible Light Absorption – this study is a new data requirement under 

40 CFR part 158 (Product Chemistry Data Requirements) for registration of a pesticide 

(food and non-food uses). The Agency will issue a data call-in for this study to support 

registration review. 

Timeline:

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

registration review. 

Registration Review for Hexaflumuron 

Projected Registration Review Timeline 

Milestone Estimated Date 

Opening the Docket 

Open Docket & Public Comment Period for Preliminary Work Plan Completed Sep. 

2009 

Close Public Comment Period Completed Nov. 

2009 

Case Development 

Final Work Plan Mar. 2010 

Issue DCI Oct. – Dec. 2010 

Data Submission Oct. – Dec. 2012 

Open Public Comment for Preliminary Risk Assessment Apr. – Jun. 2014 

Close Public Comment Period Jul. – Sep. 2014 

Registration Review Decision 

Open Public Comment for Proposed Registration Review Decision Oct. – Dec. 2014 

Close Public Comment Period Jan. - Mar. 2015 

Final Reg Review Decision and begin post-decision follow-up 2015 

Total 6 years 

Summary of Comments Received During Docket Opening:

Summary of Comments on Anticipated Data Needs

DAS Comment: DAS commented that a study to determine the anaerobic soil metabolism 

should not be required since exposure of hexaflumuron, via the termite bait system, is unlikely to 

occur in anaerobic soil conditions. DAS informed the Agency that data are available to 
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demonstrate that hexaflumuron degrades more rapidly under anaerobic conditions than under 

aerobic conditions; and, that while moderately persistent in soil under aerobic conditions, the 

formulation, packaging/delivery of hexaflumuron significantly reduces any quantity of 

hexaflumuron that may enter the soil environment. 

EPA Response: The Agency agrees that the hexaflumuron will not readily degrade in aerobic 

or anaerobic soils, therefore reducing the need for certain fate data on hexaflumuron. 

3⁄4 The Agency has modified its anticipated data needs to exclude the following OPPTS 

guideline studies: 

835.4100 (Aerobic Soil Metabolism) 

835.4200 (Anaerobic Soil Metabolism) 

DAS Comment: Based on the chemical and fate characteristics of hexaflumuron that show it to 

be relatively immobile, DAS believes the leaching and adsorption/desorption studies identified 

as anticipated data needs should not be required. 

EPA Response: EPA agrees that hexaflumuron is not likely to be mobile in soils, therefore 

reducing the need for certain fate data on hexaflumuron. 

3⁄4 The Agency has modified its anticipated data needs to exclude the following OPPTS 

guideline study: 

835.1230/1240 (Leaching and adsorption/desorption). 

DAS Comment: In its comments, DAS referenced multiple ecological toxicity studies that it 

believes may be relevant to fulfilling identified data gaps. 

EPA Response: The Agency appreciates DAS’s offer to make available hexaflumuron data that 

has not been previously submitted. While EPA will not modify its current ecotoxicity data needs 

at this time, the Agency will review the data listed below to determine if the data can be used to 

satisfy the identified data gaps for hexaflumuron. 

3⁄4 The Agency requests DAS submit the following studies: 

Cole, J. H. The Acute Contact and Oral Toxicity To Honey Bees of XRD 473. 

Unpublished report of Dow AgroSciences DET 645, 02-SEP-1985. 

Hakin, B., Anderson, A., and Chanter, D. O. The Effects of Dietary Inclusion of 

XRD 473 Technical on Reproduction in the Bobwhite Quail. Unpublished report 

of Dow AgroSciences GHE-T-184, 19 October 1988. 

Hakin, B., Anderson, A., and Chanter, D. O. The Effects of Dietary Inclusion of 

XRD 473 Technical on Reproduction in the Mallard Duck. Unpublished report of 

Dow AgroSciences GHE-T-192, 10 October 1988. 

Paterson, E. A., Toft, A. Evaluation of the pre-emergence phytotoxicity of 

hexaflumuron in a herbicide screen -2005. Unpublished report of Dow 

AgroSciences GHE-P-11276, 01-Dec-2005. 
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3⁄4 The Agency also requests DAS submit the following aquatic toxicity studies so they may 

be evaluated and considered for future risk assessments: 

Thompson, R. S. XRD 473 Technical: Acute Toxicity to the Brown Shrimp. 

Unpublished report of Dow AgroSciences 1055, 29 March 1988. 

Nozawa, T. and Annou, E. Acute Toxicity of XRD 473 to Suji Shrimp. 

Unpublished report of Dow AgroSciences GHF – R 159, 8 December 1988. 

Maeda, M. and Funaki, K. Acute Toxicity of XRD 473 to Kuruma Prawn. 

Unpublished report of Dow AgroSciences GHF – R 157, 8 December 1988. 

Jenkins, W. R., Jenkins, C. A., and O’Connor, J. The Effect of XRD 473 on the 

Survival and Reproduction of Daphnia magna. Unpublished report of Dow 

AgroSciences DET 1153, 5 September 1988. 

Smyth, D. V. and Thompson, R. S. XRD 473: Determination of Toxicity to the 

Green Algae Pseudokirchneriella subcapitata (formerly Selenastrum 

capricornutum). Unpublished report of Dow AgroSciences GHE-T-224, 19 

August 1988. 

DAS Comment: DAS provided comment(s) indicating the lack of potential exposure to 

pollinators and other [non-target insect] species to hexaflumuron. DAS noted that pollinators, 

such as honey bees, are not able to access the termite bait because it is located under ground and 

is confined within a bait cartridge whose slots are too narrow for honey bees to enter. 

Additionally, DAS noted that honey bees would not use the cellulose-based bait as a food source 

since bees have evolved to process pollen and nectar as food sources. DAS also stated that the 

associated habitat of product use precludes potential risk to either pollinators or ground-dwelling 

insects. 

DAS commented that its above-ground product, Recruit® AG (for which exposure to honey bees 

and other above-ground pollinators may exist), is not marketed in the US and, therefore, should 

not be included in the Agency’s ecological assessment. 

EPA Response: The DAS argument that Shatter® bait is located below ground and, therefore, 

unlikely to be accessed by pollinator species, applies only to above ground species, such as the 

honey bee. The Agency notes that there are several species of non-target insects which are also 

pollinators that dig (e.g. native bees). The Agency believes that some species may consume the 

cellulose and that non-target insects may also be attracted to the sports-drink additive. 

While DAS commented that its product design precludes potential exposure, EPA believes that 

DAS has not provided sufficient evidence to support its case. EPA believes that information that 

indicated exposure would be precluded would be helpful. 
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3⁄4 EPA requests that DAS provide product design specifications, such as the diameters of 

holes of bait stations used to house products containing hexaflumuron and their 

relationships to sizes of non-target insects.1 

The Agency notes that it must assess all potential uses unless a use is prohibited by the terms of 

registration. A risk assessment on DAS’s above-ground product, Recruit® AG, will be 

conducted unless the product is either cancelled or the label prohibits use within the US. 

DAS Comment: Regarding exposure to predatory species, DAS commented that non-target 

terrestrial animals and/or predators are too large to gain direct access to the termite bait because 

they are excluded from the bait by the width of the slots in the bait station. DAS commented that 

termites tunnel below ground and are not exposed above-ground unless as a member of the 

swarmer/alate caste. Therefore, termite predators that may be exposed (secondary exposure) is 

limited to a narrow set that are primarily ground-burrowing mammals whose diet primarily 

consists of earthworms. 

DAS argued that above-ground termite predators cannot be exposed to hexaflumuron because 

termite castes found outside of the colony have molted and, therefore, cannot be carrying 

hexaflumuron. 

EPA Response: The Agency agrees with the DAS that non-target terrestrial animals and/or 

predators are excluded from direct exposure (access) by the design of the bait station. Therefore, 

non-target terrestrial mammals, birds, reptiles and amphibians are only expected to be exposed to 

hexaflumuron through secondary exposure, i.e., consumption of contaminated termites (or other 

non-target insects). 

The Agency notes that subterranean termites sometimes form colonies above ground in locations 

with sufficient moisture2

. Therefore, non-target terrestrial animals (i.e., mammals, birds, reptiles 

and amphibians) may consume termites above ground that are not in the alate caste (i.e., worker 

caste). In addition, the Shatter® label states that the user should: “Identify critical areas suitable 

for placing termite stations. Critical areas include locations within or adjacent to visible termite 

activity such as: foraging tubes, termite infested plants, wood, and areas conducive to termite 

foraging (bath traps, moist soil in shaded areas, near irrigation sprinkler heads, roof down spouts 

and other moist areas, and near planting beds or other areas with plant root systems).” EPA 

suggests that if it is possible for the pesticide user to locate “visible termite activity”, then it may 

also possible for termite predators to capture those termites above ground. 

The Agency also believes it is possible that termites of all casts, including alates, may carry a 

body burden of hexaflumuron that is not sufficient to prevent molting and progression to the 

final life stages. To determine this, the Agency must understand the minimum hexaflumuron 

dose that is efficacious in termites. By way of illustration, a proposed steady-state concentration 

of 107 mg hexaflumuron/kg termite (calculated using MRID 45516725) could be considered an 

 

1 This request is voluntary and will not be required via data call‐in. 2 Suiter, D.R. Jones, S.C. and B.T. Forschler.  Biology of subterranean termites in the Eastern United States.  Ohio

State University Extension.  Bulletin 1209.  Access on line on 27 January 2010 at:  http://ohioline.osu.edu/b1209/.
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efficacious dose, and also be considered a high-end dose which is not efficacious, i.e., an upper 

bound a body burden level. 

3⁄4 The Agency requests DAS provide efficacy data to help determine potential body burden 

levels with respect to potential secondary exposure to hexaflumuron.3

DAS Comment: DAS submitted with its comments, an assessment for secondary exposure 

(short-tailed shrew) with an estimated RQ = 0.92. 

EPA Response: The Agency appreciates the analysis presented by DAS. However, the Agency 

notes that its approach for estimating exposures to mammals, as well as birds, reptiles and 

terrestrial-phase amphibians differs from that used by DAS, in that the Agency assumes a diet of 

100% termites, as opposed to DAS that assumed 8.1%. 

DAS Comment: DAS commented that hexaflumuron will not pose a risk to non-target 

terrestrial plants. DAS stated that because hexaflumuron was initially developed for use on 

agricultural crops in Europe, data are available to demonstrate the lack of potential crop injury. 

DAS noted that hexaflumuron’s mode of action (inhibition of chitin synthesis) is not relevant to 

plants. DAS also does not believe non-target plants will not be exposed to hexaflumuron, given 

its delivery system. 

EPA Response: EPA understands hexaflumuron’s mode of action. Despite knowing the mode 

of action for insects and animals, there remains no data on the effect(s) (or lack thereof) to 

plants. EPA encourages DAS to submit the plant toxicity study referenced in its comments. If 

the referenced study is submitted, the Agency will review and consider it when assessing 

potential risk to non-target plants. The Agency also believes that DAS has not provided 

sufficient information to preclude exposure of terrestrial plants to hexaflumuron. 

Summary of Other Comments by DAS 

DAS Comment: DAS provided EPA with comments regarding the use of the hexaflumuron 

termite baiting system. DAS also noted that while the above-ground termite bait product, 

Recruit® AG, is registered for use in the US but is not commercially available. 

EPA Response: The Agency appreciates the additional information on hexaflumuron and 

intends to revise its problem formulation to reflect the information in the comment. However, 

the information provided did not significantly alter the Agency’s understanding of the potential 

risk to non-target animals associated with the uses of hexaflumuron. The Agency notes that it 

must assess potential uses unless otherwise prohibited by the terms of registration. Specifically, 

regarding DAS’s above ground product, Recruit® AG, the Agency notes that unless it is 

cancelled, the Agency will conduct an assessment of this product. Similarly, the hexaflumuron 

label does not prohibit urban use. 

 

3 This request is voluntary and will not be required via data call‐in.
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DAS Comment: DAS submitted comment regarding the Agency’s conceptual diagram, and risk 

hypothesis of the problem formulation for registration review of hexaflumuron. DAS 

commented that it believes hexaflumuron will not pose an ecological risk because it cannot reach 

ecological receptors in biologically significant concentrations. Because of this, the conceptual 

diagram proposed by the Agency (i.e., the potential risk pathways for a compound based on its 

formulation(s), and use pattern(s)) is incorrect. DAS also proposed an alternative risk 

hypothesis. 

EPA Response. EPA believes that information and comments submitted by DAS does not 

preclude the presumption of potential exposure. EPA has noted how it believes that birds may 

be exposed to all termite cast types and how other non-target organisms including mammals, 

reptiles, and terrestrial phase amphibians may be potentially exposed. Therefore, EPA does not 

agree with DAS’s proposed revision of the conceptual model, or reformulated risk hypothesis. 

Since EPA believes that DAS has not provided sufficient evidence to preclude exposure, the 

Agency is requesting effects data in order to determine relevant effect levels for different taxa. 

Summary of Comments from FIFRA Endangered Species Task Force (FESTF)

Comment: The FIFRA Endangered Species Task Force (FESTF) submitted a comment that the 

Agency should ensure any company who is a technical registrant for hexaflumuron, but not a 

member of the FESTF (or a company having met its data compensation obligations) provide a 

formal offer-to-pay to FESTF in conjunction with their support of the active ingredient. 

Response: The Agency thanks FESTF for its comment and will consider this information as it 

conducts the registration review and makes its registration review decisions. 

Next Steps:

An ecological risk assessment that includes an endangered species assessment will be conducted 

to support the registration review of hexaflumuron. A human health risk assessment will be 

required if there are changes in the current use pattern that warrant such an assessment. 

The Agency will develop a DCI for the data gaps listed under the “Risk Assessment and Data 

Needs” section above.