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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 chlorfenapyr. The Final Work Plan 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 in the chlorfenapyr 

registration review docket (EPA-HQ-OPP-2010-0467) 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 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 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/. 

Chlorfenapyr (case number 7419) is a pyrrole insecticide and miticide registered for use 

in greenhouses and other structures to control mites, termites, spiders, and insects. Chlorfenapyr 

is not a restricted use pesticide. Registered uses of chlorfenapyr include residential settings, but 

applications can only be made by pest management professionals. Chlorfenapyr is a proinsecticide (i.e., the biological activity depends on its activation to another chemical). The parent 

compound is converted to the N-dealkylated metabolite, which functions as an uncoupler of 

oxidative phosphorylation in mitochondria. Chlorfenapyr was first registered in 2001 and 

therefore was not subject to the reregistration process under FIFRA. 

This document makes final the work plan for the chlorfenapyr registration review 

processes. 

Actions since Publication of PWP

A chlorfenapyr product previously contained the following label statement, “Compost 

any discarded plant material that has been treated.” The label language allowing composting has 

been removed through a label amendment. The following prohibition has been added to the 

revised final label stamped November 2, 2010, “DO NOT compost any discarded plant materials 

that have been treated with this product.” 

Comments Received on Preliminary Work Plan 

 On June 23, 2010 EPA opened a 60-day public comment period for the registration 

review of chlorfenapyr. The comment period ended on August 23, 2010. The Preliminary Work 

Plan document can be located in the chlorfenapyr registration review docket (EPA-HQ-OPP2010-0467) at www.regulations.gov. 
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During the public comment period, the Agency received comments from the BASF 

Corporation, the FIFRA Endangered Species Task Force (FESTF), and the Physicians 

Committee for Responsible Medicine (PCRM). A detailed description of the BASF and PCRM 

comments as well as the Agency’s response to these comments is available in separate response 

memoranda from the Agency’s Environmental Fate and Effects Division (EFED) and Human 

Health Effects Division (HED), which can be located in the chlorfenapyr registration review 

docket (EPA-HQ-OPP-2010-0467) at www.regulations.gov. The Agency’s response to FESTF’s 

comment is below. The comments received change the anticipated data and risk assessment 

needs that were described in the PWP; however, the timeline remains unchanged. The revised 

anticipated data and risk assessment needs are detailed below. 

 In the PWP, EPA solicited comments on three specific topics: environmental justice, 

water body impairment and trade irritants. No comments or information were received during 

the public comment period concerning these issues. 

Comment from FESTF

In June of 2004, March of 2005, and October 19, 2007, the FIFRA Endangered Species 

Task Force (FESTF) submitted its Information Management System (FESTF Information 

Management System (IMS): Documentation of Structure and Function of IMS 1.1, MRID # 

46325901) and documentation of the beta-tested IMS, NatureServe data (FESTF Task Force 

Information Management System (IMS): Beta-Tested IMS 2.0 and Access to NatureServe Data -

Final Report, MRID #46486301) and NatureServe Data Evaluation and Review (MRID 

#47260101). These data fulfill the data requirements spelled out in Pesticide Registration Notice 

2000-2 and provide the best available data necessary for the proximity analysis of Chlorfenapyr

use and listed species locations. 

The leading registrant, as identified on the fact sheet included in the Registration Review 

Summary, is BASF Corporation (BASF), a FESTF member. BASF is entitled to rely on FESTF 

data (See Attachment A for our current list of members and companies who have reached an 

agreement allowing reliance on FESTF data submissions). 

Agency Response

The Agency thanks FESTF for its comment. As discussed below in the Anticipated Risk 

Assessment and Data Needs section, the Agency has determined that there is no outdoor 

environmental exposure from the use of chlorfenapyr and will not conduct an ecological risk 

assessment during registration review. 

Anticipated Risk Assessment and Data Needs

The Agency anticipates conducting a comprehensive human health risk assessment for all 

uses of chlorfenapyr and its metabolites of concern. Below is a summary of the issues relevant 

to the registration review process for chlorfenapyr. 
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Ecological Risk 

In the PWP, the Agency anticipated conducting a comprehensive ecological risk 

assessment, including an endangered species assessment, for all uses of chlorfenapyr and its 

metabolites of concern. This was due to two uses that could result in outdoor environmental 

exposure. However, due to a label amendment explained below and re-examination of potential 

environmental exposure, the Agency has determined that there is no environmental exposure, 

and an ecological risk assessment is not needed. 

The first use identified in the PWP as having potential outdoor environmental exposure 

was application to fruiting vegetables grown in a greenhouse. The Agency believed that 

exposure could occur because the label stated to “Compost any discarded plant material that has 

been treated.” However, following publication of the PWP, the registrant amended the label to 

prohibit composting of chlorfenapyr-treated material. Therefore, the Agency has determined that 

this use no longer results in outdoor environmental exposure and an ecological risk assessment 

for this use is not needed. 

The second use identified in the PWP as having potential outdoor environmental exposure 

was application to soil underlying a concrete slab prior to the slab being poured (during 

construction). The PWP stated that there is a potential for exposure to chlorfenapyr in adjacent 

areas via runoff from the use site if a major rain event occurred after application but prior to 

pouring of the concrete slab. However, after re-examining this use pattern, the Agency has 

determined that the potential for outdoor environmental exposure is negligible. This is due to the 

fact that a small area would be treated before the concrete was applied and the time between 

application and pouring of the concrete slab would be minimal. Therefore, the Agency 

concludes that outdoor environmental exposure would not occur as a result of this use and an 

ecological risk assessment for this use is no longer needed. 

Refer to the document, Registration Review –Problem Formulation Revised Based on 

Public Comments for Ecological Risk, Environmental Fate, and Endangered Species 

Assessments for Chlorfenapyr (PC Code 129093; DP Barcode 383511), for a detailed discussion 

of the anticipated ecological risk assessment needs. 

Human Health Risk: 

A summary of the anticipated risk assessment and data needs for the human health 

assessment follows: 

• As part of registration review, the Agency anticipates conducting a new dietary risk 

assessment which utilizes the most current version of DEEM-FCIDTM (2.03). The new 

dietary exposure assessment will evaluate potential secondary residues of chlorfenapyr 

and its metabolites in/on livestock commodities due to consumption of feed items with 

chlorfenapyr residues resulting from the established food/feed handling area use. If any 

proposed uses of chlorfenapyr are deemed to result in contamination of drinking water, 

estimated drinking water concentrations (EDWCs) will be incorporated in the dietary 

assessment. 
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• As part of registration review, the Agency also expects to conduct revised residential 

postapplication as well as occupational handler and postapplication assessments. The 

revised residential assessment will include dermal and incidental oral routes of exposure. 

Two occupational handler scenarios that were not previously assessed will be assessed 

during registration review and, in addition, several occupational handler scenarios may 

need to be assessed in accordance with changes to the hazard assessment. The 

occupational post application exposure assessment will be conducted using current labeled 

application rates, updated transfer coefficients, and in accordance with changes to the 

hazard assessment. 

• To reflect current Agency policy, the tolerance expression in 40 CFR Part 180.513 will be 

reviewed during registration review to ensure that it appropriately covers the metabolites 

and degradates of chlorfenapyr and that it specifies the residues to be measured for each 

commodity. 

• The FQPA factor will also need to be evaluated based upon the changes in policy, the 

developmental neurotoxicity (DNT), 28-dermal, immunotoxicity, and 90-day inhalation 

studies. These studies may also lead to revision of the current endpoints for future risk 

assessments. 

• The Agency anticipates needing the following data in order to conduct a complete human 

health risk assessment for chlorfenapyr: 

o Guideline 870.7800 - Immunotoxicity (chlorfenapyr) 

• The PWP included guideline 870.3200 - 28-day Dermal Toxicity (rat) and Guideline 

870.3465 - 90-day Inhalation Toxicity (rat) as anticipated data needs; however, the 

studies have been submitted to the Agency. Therefore, it appears at this time that 

pending review, they may not need to be called in during registration review. 

• Please refer to the document, Chlorfenapyr - Human Health Assessment Scoping 

Document in Support of Registration Review, for a detailed discussion of the anticipated 

risk assessment and data needs for human health. 

Other anticipated data needs:

• Guideline 830.7050 - UV/Visible Light Absorption. This study is a new data 

requirement under 40 CFR Part 158 for registration of a pesticide (food and non-food 

uses). The Agency anticipates requiring this study to obtain basic information about the 

compound’s identity/composition and the wavelengths at which the compound may be 

susceptible to photochemical degradation. 

Endocrine Disruptor Screening Program:

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (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 endocrine effects as the Administrator may 
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designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact 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 quantitative relationship between the dose and the E, A, or T effect. 

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 ingredients and 9 inert 

ingredients. This list of chemicals was selected based on the potential for human exposure 

through pathways such as food and water, residential activity, and certain post-application 

agricultural scenarios. This list should not be construed as a list of known or likely endocrine 

disruptors. 

Chlorfenapyr is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing EDSP orders/data call-ins for all Registration 

Review cases, including those for which EPA has already opened a Registration Review docket 

for a pesticide active ingredient. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: 

http://www.epa.gov/endo/.

Timeline:

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

registration review. 
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Registration Review for Chlorfenapyr – Projected Registration Review Timeline

Activities Estimated Date 

Opening the docket 

Open Docket and Public Comment Period 2010 – June 

Close Public Comment 2010 – August 

Case Development 

Final Work Plan 2010 – November 

Issue DCI 2011 – July – Sept. 

Data Submission 2013 – July – Sept. 

Open Public Comment Period for Preliminary Risk Assessments 2015 – Jan. – March 

Close Public Comment Period 2015 – April - June 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review Decision 2015 – July - Sept. 

Close Public Comment Period 2015 – Oct. – Dec. 

Final Registration Review Decision and Begin Post-Decision Follow-up 2016 

Total (years) 6 

Next Steps

The Agency plans to issue a Data Call-In (DCI) for chlorfenapyr in 2011. These new 

data will be used to conduct the risk assessments outlined in this FWP for all chlorfenapyr uses.