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Propoxur Proposed Interim Decision 

Table of Contents

Contents

I. INTRODUCTION...................................................................................3

A. Summary of Propoxur Registration Review..................................................4

II. USE AND USAGE...................................................................................5

III. SCIENTIFIC ASSESSMENTS....................................................................5

A. Human Health....................................................................................6

1. Risk Conclusions...........................................................................6

2. Human Incidents............................................................................7

3. Tolerances....................................................................................8

B. Ecological.........................................................................................8

1. Risk Conclusions............................................................................8

2. Ecological Incidents..........................................................................9

3. Characterization of Ecological Risk........................................................9

C. Endangered Species Assessment.............................................................10

D. Endocrine Disruptor Screening Program....................................................11

IV. PROPOSED INTERIM REGISTRATION REVIEW DECISION...........................12

A. Risk Mitigation and Regulatory Rationale..................................................12

B. Proposed Interim Registration Review Decision...........................................12

V. NEXT STEPS AND TIMELINE..................................................................12

A. Interim Registration Review Decision........................................................13

B. Implementation of Mitigation Measures......................................................13

Appendix A: Summary of Actions Taken for Propoxur.................................................14

Appendix B: Propoxur Label Table........................................................................15
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I. INTRODUCTION

This document is the Environmental Protection Agency’s (EPA or the Agency) Proposed Interim 

Registration Review Decision for propoxur (case 2555, PC code 047802) and is being issued 

pursuant to 40 CFR sections 155.56 and 155.58. A registration review decision is the Agency's 

determination whether a pesticide meets, or does not meet, the standard for registration in the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it 

determines it to be appropriate, an Interim Registration Review Decision before completing a 

registration review. Among other things, the Interim Registration Review Decision may: 1)

require new risk mitigation measures; 2) impose interim risk mitigation measures; 3) identify 

data or information required to complete the review; and 4) include schedules for submitting the 

required data, conducting the new risk assessment and completing the registration review. For 

further information on propoxur, additional documents can be found in EPA’s public docket 

(EPA-HQ-OPP-2009-0806) at www.regulations.gov.

FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the 

continuous review of existing pesticides. All pesticides distributed or sold in the United States 

generally must be registered by the EPA based on scientific data showing that they will not cause 

unreasonable risks to human health or to the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

and reduce risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the registration review 

program, the Agency periodically re-evaluates pesticides to make sure that as these changes 

occur, products in the marketplace can continue to be used safely. Information on this program is 

provided at http://www.epa.gov/pesticide-reevaluation/registration-review-process. 

In 2006, the Agency implemented the registration review program pursuant to FIFRA section 

3(g) and will review each registered pesticide every 15 years to determine whether it continues to 

meet the FIFRA standard for registration.

EPA is issuing a proposed interim registration review decision for propoxur so that it can (1) 

move forward with aspects of the registration review that are complete and (2) implement 

interim risk mitigation. The Agency will complete endocrine screening for propoxur, pursuant to 

the Federal Food, Drug, and Cosmetic Act (FFDCA) section 408(p), before completing this 

registration review. Due to low usage and negligible exposure, the Agency does not expect 

propoxur to have direct or indirect adverse effects to non-listed and listed species or to 

designated critical habitat. As such, EPA has made a “No Effect” determination under the 

Endangered Species Act (ESA) for all listed species and designated critical habitat for such 

species. In addition, a pollinator risk assessment will not be required for propoxur due to 

negligible exposure pathways to terrestrial invertebrates (honeybees). For further information, 

see the Preliminary Environmental Fate and Ecological Risk Assessment for Registration Review 

of Propoxur, dated August 6, 2014 and the Addendum Memorandum Clarifying the Preliminary 

Environmental Fate and Ecological Risk Assessment Conclusions for the Registration Review of 
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Propoxur. These documents are available in the public docket EPA-HQ-OPP-2009-0806, which 

can be accessed at http://www.regulations.gov/.

Propoxur is a residual N-methyl carbamate insecticide registered to control ants, roaches, 

hornets, and other pests in and around commercial, industrial, and institutional buildings, and 

outside residences. There are 22 FIFRA Section 3 registrations. A Reregistration Eligibility

Decision (RED) for propoxur was issued in August 1997.

A. Summary of Propoxur Registration Review

Pursuant to 40 CFR Section 155.50, EPA formally initiated registration review for propoxur 

(case 2555) in December 2009. The following timeline highlights significant events that have 

occurred during the registration review of propoxur and can be found in EPA’s public docket,

EPA-HQ-OPP-2009-0806, accessed at www.regulations.gov:

• December 14, 2009 – Publication of Summary Document for a 60-day public comment 

period. The Summary Document included the Preliminary Work Plan (PWP) and was 

accompanied by the scoping document and problem formulation. Comments were 

submitted by the registrant McLaughlin Gormley King Company (MGK) and by the 

Natural Resources Defense Council (NRDC). MGK commented that loose granular baits 

were no longer registered for outdoor use, that there is low usage of propoxur, and 

therefore, no significant environmental exposure. Subsequent to the publication of the 

FWP, EPA confirmed that all products formulated as loose granules for outdoor

application were cancelled and therefore, that use pattern was not assessed as part of the

most recent ecological risk assessment. NRDC commented that they had petitioned the 

USEPA to cancel the pet collar uses of propoxur on November 26, 2007 and 

supplemented that petition on April 29, 2009. In 2014, EPA and the propoxur pet-collar

manufacturers reached an agreement to cancel all propoxur pet collar products. All 

propoxur pet collar products were cancelled effective April 1, 2015 and, therefore, were 

not considered in the most recent human health risk assessment for propoxur. The 

product cancellation order for all propoxur pet collar products can be accessed at 

www.regulations.gov, Docket ID EPA-HQ-OPP-2009-0207-0193. 

• June 17, 2010 - Final Work Plan (FWP) for propoxur was issued. 

• March 30, 2011 – Generic Data Call-In (GDCI) for propoxur was issued. All required 

data were submitted and reviewed.

• July 8, 2015 – The Agency published the Preliminary Ecological Risk Assessment for the 

Registration Review of Propoxur and the Registration Review Draft Human Health Risk 

Assessment for Propoxur for a 60-day public comment period. No comments were 

received.
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• September 22, 2015 – Final Cancellation Order for all indoor aerosol, spray and liquid 

formulations, food handling establishments, and indoor crack and crevice uses was published.

See Section II. for additional information concerning the cancellation. These uses are 

currently cancelled for all technical products containing propoxur. The Agency is completing 

the cancellation process to cancel or amend end-use products that were registered for these 

uses. The use cancellation order can be accessed at www.regulations.gov, Docket ID EPAHQ-OPP-2015-0296-0003.

• March 2016 – The Agency is now publishing the following documents in docket number 

EPA-HQ-OPP-2009-0806 for a 60-day public comment period:

o Propoxur Proposed Interim Registration Review Decision

o Characterization of Propoxur Spot Treatments

o Addendum Memorandum Clarifying the Preliminary Environmental Fate and 

Ecological Risk Assessment Conclusions for the Registration Review of Propoxur

II. USE AND USAGE

Propoxur is a residual N-methyl carbamate insecticide registered for use to control synanthropic 

arthropods. Propoxur is an acetylcholinesterase inhibitor that is effective against a wide range of 

insects, arachnids, and other terrestrial arthropods. Propoxur products are currently registered 

for limited indoor and outdoor use. Registered use sites include outdoor structural perimeter 

applications and outdoor spot treatments, bait in bait stations (indoor and outdoor), pastes

(indoor and outdoor), impregnated shelf paper (indoor and outdoor), and impregnated insect tape

(indoor and outdoor). When the most recent propoxur registration review risk assessments were 

completed, propoxur was also registered for indoor use in institutional and industrial settings as 

aerosol, spray and liquid formulations for cracks and crevice and food-handling establishment 

use. These uses were considered in the risk assessments but since then have been cancelled in 

order to mitigate dietary and residential post-application risks of concern. These uses were 

cancelled effective September 22, 2015. These uses are currently cancelled for all technical 

products containing propoxur. The Agency is completing the cancellation process to cancel or 

amend end-use products that were registered for these uses. The use cancellation order is 

available in the public docket EPA-HQ-OPP-2015-0296, which can be accessed at 

http://www.regulations.gov/. 

The current usage data available for propoxur are very limited. Propoxur is a minor chemical 

used in the professional pest management sector. Between 2001 and 2003, the reported annual 

pounds active ingredient (a.i.) used were 8,000-9,000 lbs, accounting for less than 1% of the total 

reported chemicals applied each year in the pest management sector (See Use and Usage 

Information for Propoxur, dated October 7, 2009). In 2012, reported usage had decreased to 261 

lbs in the Pest Control Operator (PCO) market (Non-agricultural Market Research Data, 2012). 
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III. SCIENTIFIC ASSESSMENTS

A. Human Health 

A summary of the Agency’s human health risk assessment is presented below. The Agency used 

the most recent Agency science policies and risk assessment methodologies to prepare a 

quantitative risk assessment in support of the registration review of propoxur. For a detailed 

discussion of the human health assessment for propoxur, see Propoxur: Human Health Draft 

Risk Assessment, dated May 22, 2015. This document is available in the public docket EPA-HQOPP-2009-0806, which can be accessed at http://www.regulations.gov/.

1. Risk Conclusions

When the draft human health risk assessment was conducted propoxur was registered, amongst 

other things, for indoor crack and crevice applications (liquid and aerosol formulations) in food 

handling establishments (FHE) and institutional settings (i.e., hospitals, dormitories) and these 

uses were considered in the human health risk assessment. After the risk assessment was 

completed, the technical registrant voluntarily canceled these uses to mitigate identified dietary 

and residential post-application risks of concern. 

Dietary Assessment

An acute dietary (food only) assessment was conducted for the food handling establishment uses 

of propoxur. Exposure from drinking water is not expected and therefore a drinking water 

assessment was not conducted. 

Acute dietary (food only) risks exceed the Agency’s level of concern for the U.S. general 

population and all population subgroups. The acute dietary exposure for propoxur is estimated at 

550% of the acute population adjusted dose (aPAD) for the U.S. general population and 1400% 

of the aPAD for children 1-2 years old. To mitigate these risks (after the human health risk 

assessment was completed) the technical registrant voluntarily cancelled all FHE, indoor liquid 

and aerosol formulations, and indoor crack and crevice uses. The remaining registered uses (bait

stations, pastes, impregnated shelf paper and strips, and outdoor spot treatments) do not result in 

dietary exposure. 

Residential Assessment

Residential handler exposure to enclosed/containerized bait stations and impregnated shelf paper 

products is considered to be negligible and therefore, a quantitative residential handler 

assessment for these uses was not conducted. Residential handler inhalation (non-cancer) and 

cancer (dermal and inhalation) exposure and risks were estimated for outdoor crack and crevice, 

spot, and perimeter treatments using ready to use (RTU) aerosol cans. No risks of concern were 

identified for residential handlers. 

Residential post-application exposure and risks were assessed for use of propoxur to treat for 

bedbugs in institutional settings (military barracks, dormitories, etc.), and crack and crevice use 

in institutional settings (hospital waiting rooms). For residential post-application exposure, 
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incidental oral risks were identified for children resulting from crack and crevice treatment (of 

carpets) in institutional settings. The incidental oral margin of exposure (MOE) for children

coming in contact with treated carpet surfaces in institutional settings (hospital waiting rooms) is 

60 (target incidental oral MOE = 100). To mitigate these risks (after the human health risk 

assessment was completed) the technical registrant voluntarily cancelled all FHE, indoor liquid 

and aerosol formulations, and indoor crack and crevice uses. The remaining registered uses (bait 

stations, pastes, impregnated shelf paper and strips, and outdoor spot treatments) do not result in 

residential post-application risks of concern. 

Aggregate Assessment

A short-term aggregate exposure and risk assessment was conducted for (background) dietary, 

inhalation residential, and incidental oral residential exposure. Since the level of concern for the 

dietary, inhalation, and incidental oral routes are different, an aggregate risk index (ARI) was 

used to calculate aggregate risk estimates. An ARI of less than 1 results in risk estimates of 

concern. Short-term aggregate risks of concern were identified for children (1-2) (ARI = 0.8). 

To mitigate these risks (after the human health risk assessment was completed) the technical 

registrant voluntarily cancelled all FHE, indoor liquid and aerosol formulations, and indoor crack 

and crevice uses. The remaining registered uses (bait stations, pastes, impregnated shelf paper 

and strips, and outdoor spot treatments) do not result in aggregate risks exceeding levels of 

concern.

Cumulative Assessment

Propoxur is a member of the N-methyl carbamate (NMC) common mechanism group and was 

included in the 2007 NMC risk assessment. The Agency will conduct an updated cumulative 

assessment for the NMC upon the completion of all individual assessments. This document is 

available in the public docket EPA-HQ-OPP-2007-0935, which can be accessed at 

http://www.regulations.gov/.

Occupational Assessment

An occupational handler exposure and risk assessment was conducted and no risks of concern 

were identified. Occupational post-application exposure and risk assessments were not 

conducted because dermal post-application exposure is not expected, and inhalation postapplication exposure is unlikely to occur. 

2. Human Incidents

As part of the 2015 human health risk assessment, EPA completed a review of propoxur

incidents in the OPP Incident Data System (IDS) and the Centers for Disease Control and 

Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel Event 

Notification System for Occupational Risk-Pesticides (SENSOR) databases. Based on the low 

frequency and low severity of incident cases reported for propoxur in both IDS and NIOSH 

SENSOR, and that many of the products implicated in the reported incidents were cancelled 

either in 2007 (indoor residential products) or 2015 (pet collars), there does not appear to be a 

concern at this time that would warrant further investigation. The Agency will continue to 
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monitor the incident information and if a concern is triggered, additional analysis will be 

conducted.

3. Tolerances

There are currently no tolerances established for propoxur. The Agency does not recommend the

establishment of tolerances because all indoor crack and crevice uses in food handling 

establishments have been voluntarily cancelled.

B. Ecological

On August 6, 2014, the Agency published the Preliminary Environmental Fate and Ecological 

Risk Assessment for the Registration Review of Propoxur. Since the draft ecological risk 

assessment was posted to the docket, the risk assessment has been amended by the Addendum 

Memorandum Clarifying the Preliminary Environmental Fate and Ecological Risk Assessment 

Conclusions for the Registration Review of Propoxur. As a result of this addendum, the Agency 

has changed the risk determination for listed freshwater aquatic invertebrates from “May Effect”

to “No Effect”. A summary of the Agency’s ecological risk assessment is presented below. The 

Agency used the most updated Agency science policies and risk assessment methodologies to 

prepare a qualitative risk assessment in support of the registration review of propoxur. For a 

detailed discussion of the ecological assessment for propoxur, see the Preliminary

Environmental Fate and Ecological Risk Assessment for Registration Review of Propoxur and

the Addendum Memorandum Clarifying the Preliminary Environmental Fate and Ecological 

Risk Assessment Conclusions for the Registration Review of Propoxur. These documents are

available in the public docket EPA-HQ-OPP-2009-0806, which can be accessed at 

http://www.regulations.gov/.

1. Risk Conclusions

Terrestrial Assessment

Terrestrial exposure is not expected because outdoor use is limited (bait stations; outdoor crack 

and crevice spot treatments); registered uses are not expected to serve as attractive food sources 

to birds, mammals, or terrestrial invertebrates; and data indicate very low volume of propoxur 

use outdoors. Therefore, there are no risks of concern for non-target non-listed and listed

terrestrial organisms and plants based on the lack of a complete exposure pathway and limited 

exposure due to low use.

A pollinator risk assessment will not be required for propoxur. Pollinator exposure and effects 

data are not necessary to make a final registration review decision for propoxur due to negligible 

exposure pathways to terrestrial invertebrates (honeybees) based on currently registered uses. For 

further information, see the Preliminary Environmental Fate and Ecological Risk Assessment for 
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Registration Review of Propoxur, dated August 6, 2014. This document is available in the public 

docket EPA-HQ-OPP-2009-0806, which can be accessed at http://www.regulations.gov/.

Aquatic Assessment

Based on currently registered uses, aquatic exposure is expected to be limited. The only use 

scenario that could result in potential aquatic exposure is outdoor handheld spray spot treatments 

that occur close to streams and other waterbodies. Although exposure is expected to be minimal, 

propoxur has high mobility and persistence in the environment and there is potential for runoff of 

propoxur to water where applications occur close to water bodies. The only potential aquatic 

risk identified in the preliminary ecological risk assessment was acute risk to listed aquatic 

invertebrates resulting from spot treatment use occurring close to streams or water bodies. A 

threshold analysis relating the exposure necessary to induce adverse impacts was conducted to 

describe potential exposure for aquatic organisms and it was determined that acute effects to 

listed aquatic invertebrates may occur when greater than or equal to 2.75 gallons of product are 

applied per use site per year. While this potential for exposure exists, the potential is low 

because product usage at 2.75 gallons per spot treatment represents higher application than is 

expected given the available usage data. Since the preliminary ecological risk assessment was 

posted to the docket, the Biological and Economic Analysis Division (BEAD) has provided 

additional information on propoxur outdoor spot treatment use, which support that propoxur is 

not likely to be used at quantities near 2.75 gallons per use site per year. The preliminary

propoxur ecological risk assessment has been amended to reflect this use information and

indicates that there is no reasonable expectation for any registered use of propoxur to cause 

direct or indirect adverse effects to threatened or endangered species. Therefore, EPA has made 

a “No Effect” determination for all listed taxa including listed freshwater aquatic invertebrates. 

This determination supersedes the “May Effect” risk determination for listed freshwater aquatic 

invertebrates presented in the risk assessment.

No other acute risks of concern were identified for all other listed and non-listed aquatic 

organisms (freshwater fish, estuarine/marine fish, estuarine/marine invertebrates, aquatic plants). 

For further information see, the Addendum Memorandum Clarifying the Preliminary 

Environmental Fate and Ecological Risk Assessment Conclusions for the Registration Review of 

Propoxur. This document is available in the public docket EPA-HQ-OPP-2009-0806, which can 

be accessed at http://www.regulations.gov/.

2. Ecological Incidents

A review of all available information in the following incident databases was completed in April 

2014 covering incidents occurring from 1992 to 2014: Ecological Incident Information System 

(EIIS) and the Avian Monitoring Information System (AIMS). Based on a search of EIIS, the 

Agency has received three reports of adverse field effects to non-target plants linked to propoxur. 

A query of AIMS resulted in 13 reports of incidents associated with propoxur. Most of the 

incidents were minor plant incidents, while three incidents involved birds and additional 

chemicals used in conjunction with propoxur. For a detailed discussion of the ecological 

incidents for propoxur, see the Preliminary Environmental Fate and Ecological Risk Assessment 

for Registration Review of Propoxur, dated August 6, 2014.
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3. Characterization of Ecological Risk

The preliminary risk assessment for propoxur initially identified potential risks of concern for 

listed aquatic invertebrates only. However, since the preliminary ecological risk assessment was 

posted to the docket, additional information on propoxur outdoor spot treatments was provided 

by the Biological and Economic Analysis Division (BEAD). An addendum to the preliminary 

ecological risk assessment was completed to reflect this usage information and to amend the 

preliminary risk assessment. The amended ecological risk assessment indicates that there is no 

reasonable expectation for any registered use of propoxur to cause direct or indirect adverse 

effects to threatened or endangered species. This risk characterization section is intended to 

provide context and describe the lines of evidence used to identify risk.

Aquatic Species

The only propoxur use that could result in aquatic exposure is outdoor handheld spray spot 

treatment application that occurs close to streams and other water bodies. Although there is the 

potential for runoff of propoxur to aquatic environments from outdoor handheld spray spot 

treatments occurring near water bodies, aquatic exposure is likely minimal because spot 

treatment applications are non-broadcast. Furthermore, the current use volume of propoxur is 

relatively limited based on nationwide data. 

A quantitative ecological risk assessment was not conducted and estimated environmental 

concentrations (EECs) and risk quotients (RQs) were not calculated because standard exposure 

scenarios have not been developed to calculate exposure for outdoor handheld spray spot 

treatments, and the maximum application rate is not specified on labels. Instead, a threshold 

analysis relating the exposure necessary to induce adverse impacts was conducted to describe 

potential exposure for aquatic organisms based on its expected use as an outdoor spot treatment. 

It was determined that acute effects to listed aquatic invertebrates may occur, resulting from 

hand-held spray applications, when greater than or equal to 2.75 gallons of product are applied

per use site per year. While the potential for exposure exists, the potential is low because 

product usage at 2.75 gallons per spot treatment would represent an application volume much 

greater than is expected given the available usage data. In addition, the limited use of propoxur 

also suggests that it is not widely used in an organized fashion within communities. Therefore, 

the amount of material used in outdoor spot treatments is not likely to be in copious amounts and 

not likely to be distributed widespread among different regions.

Since the preliminary ecological risk assessment was posted to the docket, additional information 

on propoxur outdoor spot treatments was provided by the Biological and Economic Analysis 

Division (BEAD). An addendum to the preliminary ecological risk assessment was completed to 

reflect this usage information and to amend the preliminary risk assessment. BEAD estimates 

that outdoor spot treatments of propoxur would not exceed one gallon of formulated product per 

property per year. This usage information is further evidence that propoxur is not used at 

quantities approaching 2.75 gallons per spot treatment. The amended ecological risk assessment 

indicates that there is no reasonable expectation for any registered use of propoxur to cause 

direct or indirect adverse effects to threatened or endangered species. A “No Effect” 
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determination was made for all federally listed species and designated critical habitat. For 

further information, see Characterization of Propoxur Spot Treatments and the Addendum 

Memorandum Clarifying the Preliminary Environmental Fate and Ecological Risk Assessment 

Conclusions for the Registration Review of Propoxur. This document is available in the public 

docket EPA-HQ-OPP-2009-0806, which can be accessed at http://www.regulations.gov/.

C. Endangered Species Assessment

There is no reasonable expectation for any propoxur product to cause direct or indirect adverse 

effects to threatened or endangered species. No adverse modification of critical habitat is 

expected to occur from use of propoxur. This is because the type and limited extent of outdoor 

use is not likely to result in exposure that will result in risks exceeding levels of concern for nonlisted and listed species. EPA has made a “No Effect” determination under the Endangered 

Species Act (ESA) for all listed species and designated critical habitat for such species and has 

therefore concluded that consultation with the U.S. Fish and Wildlife Service and the National 

Marine Fisheries Service under ESA section 7(a)(2) is not required. For details see, the 

Preliminary Environmental Fate and Ecological Risk Assessment for Registration Review of 

Propoxur and the Addendum Memorandum Clarifying the Preliminary Environmental Fate and 

Ecological Risk Assessment Conclusions for the Registration Review of Propoxur. These 

documents are available in the public docket EPA-HQ-OPP-2009-0806, which can be accessed 

at http://www.regulations.gov/.

D. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, sub-chronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision for propoxur, EPA reviewed 

these data and selected the most sensitive endpoints for relevant risk assessment scenarios from 

the existing hazard database. However, as required by FFDCA section 408(p), propoxur is

subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the 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 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 
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testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. 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. A second list of 

chemicals identified for EDSP screening was published on June 14, 20131 and includes some 

pesticides scheduled for Registration Review and chemicals found in water. Propoxur was not 

included on either of the first two lists for EDSP screening. Neither of these lists should be 

construed as a list of known or likely endocrine disruptors. For further information on the status 

of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test guidelines 

and the Tier 1 screening battery, please visit our website.2 

In this proposed interim decision, EPA is making no human health or environmental safety 

findings associated with the EDSP screening of propoxur. Before completing this Registration 

Review, the Agency will make an EDSP FFDCA section 408(p) determination.

IV. PROPOSED INTERIM REGISTRATION REVIEW DECISION

A. Risk Mitigation and Regulatory Rationale

Human Health Risk

Non-cancer risks of concern from propoxur were identified for dietary (food only) exposure and 

residential post-application exposure. The technical registrant voluntarily cancelled all indoor 

aerosol, spray and liquid formulations, indoor crack and crevice and food-handling establishment 

(FHE) uses to mitigate the identified dietary and post-application risks. These uses were canceled 

effective September 22, 2015. These uses are currently cancelled for all technical products 

containing propoxur. All technical and manufacturing use product labels must be amended to 

include formulation restriction language. The Agency is completing the cancellation process to 

cancel or amend end-use products that were registered for these uses. The remaining registered

uses, which are bait stations, pastes, impregnated shelf paper and strips, and outdoor spot 

treatments, do not result in dietary (no dietary exposure) and residential post-application risk. 

The use cancellation order is available in the public docket EPA-HQ-OPP-2015-0296, which can 

be accessed at http://www.regulations.gov/.

B. Proposed Interim Registration Review Decision

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this Proposed 

Interim Registration Review Decision. Except for the EDSP components of the propoxur 

registration review case, the Agency has made the following Proposed Interim Registration 

Review Decision: (1) no additional data are required at this time; and (2) changes to the affected 

registrations and their labeling are needed at this time. A pollinator risk assessment will not be 

required for propoxur due to negligible exposure pathways to terrestrial invertebrates 

(honeybees). In addition, the Agency does not expect propoxur to have direct or indirect adverse 

 1 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of chemicals. 2 http://www.epa.gov/endo/
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effects to non-listed and listed species or to designated critical habitat. As such, EPA has made a 

“No Effect” determination under the Endangered Species Act (ESA) for all listed species and 

designated critical habitat for such species.

V. NEXT STEPS AND TIMELINE

A. Interim Registration Review Decision

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this Proposed 

Interim Registration Review Decision, and placing it in the propoxur registration review docket 

(EPA-HQ-OPP-2009-0806). A Federal Register Notice will announce the availability of this 

Proposed Interim Registration Review Decision and initiate a 60-day public comment period. If 

there are no significant comments or additional information submitted to the docket during the 

comment period that leads the Agency to change its proposed decision, EPA will issue an 

Interim Registration Review Decision for propoxur (case 2555). 

B. Implementation of Mitigation Measures

The technical registrant voluntarily cancelled all indoor aerosol, spray and liquid formulations, 

indoor crack and crevice and food-handling establishment (FHE) uses to mitigate the identified 

dietary and post-application risks. These uses were canceled effective September 22, 2015. 

These uses are currently cancelled for all technical products containing propoxur. All technical 

and manufacturing use product labels must be amended to include formulation restriction 

language. The Agency is completing the cancellation process to cancel or amend end-use 

products that were registered for these uses. The mitigation measures which have already been

taken to cancel certain uses and associated label amendments to address the human health risks 

of concern are described in Appendices A and B below.
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Appendix A: Summary of Actions Taken for Propoxur

Registration Review Case#: 2555

PC Code: 047802

Propoxur Type: Insecticide

Propoxur Family: N-methyl Carbamate

Mode of Action: Acetylcholinesterase inhibitor

Affected 

Population(s)

Source of 

Exposure

Route of 

Exposure

Duration of 

Exposure

Risk of 

Concern

Proposed and/or 

Taken Action(s)

Comment 

Human Health

U.S. General 

Population

Children (1-2)

Human Health

(food handling 

establishment, 

indoor aerosol, 

spray and liquid 

formulations, 

and indoor 

crack and 

crevice uses)

Dietary 

(food)

Incidental 

oral (hand-tomouth, 

children)

Human Health 

 Dietary

 Postapplication 

Residential

 Short and 

intermediate

 Acute

Human Health 

Acute 

Dietary 

aPAD = 

550%

(General 

Population); 

1400% 

(Children 

(1-2))

Incidental 

Oral MOE 

= 60

Human Health: 

Dietary & Incidental

Oral Risk Mitigation

Voluntary 

cancellation

(action taken): All 

indoor aerosol, 

spray and liquid 

formulations, 

indoor crack and 

crevice use and 

use in foodhandling 

establishments.

HH RA 

identified 

dietary and 

postapplication 

residential 

risks 

exceeding 

levels of 

concern. 

These risks 

were fully 

mitigated by

voluntary 

cancellations

of certain 

uses. There 

are no 

remaining 

food uses; 

there are no 

tolerances for 

propoxur.
15

Appendix B: Propoxur Label Table

Summary of Proposed Labeling Changes for Propoxur Uses

Description Amended Labeling Language for Propoxur Use Products Placement on 

Label

For Technical 

and all 

Manufacturing 

Use Products

“Not for formulation into aerosol or liquid products for indoor use.” First line in the 

“Directions for 

Use”