2

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF PREVENTION, 

PESTICIDES, AND TOXIC SUBSTANCES

Problem Formulation 

For 

Propoxur Environmental Fate And Ecological Risk 

Assessment 

2 – (1 – Methylethoxy) phenol methylcarbamate 

Prepared by: 

Ron Parker, Ph.D. 

Joseph DeCant, M.S. 

Reviewed by: 

Allen Vaughan, Senior Biologist 

Mah Shamim, Ph.D., Branch Chief 

Environmental Risk Branch V 

United States Environmental Protection 

Agency 

Office of Pesticide Programs 

Environmental Fate and Effects Division 

Environmental Risk Branch V 

401 M Street, SW 

Mail Code 7507C 

Washington, D.C. 2046

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Table of Contents 

1. Purpose....................................................................................................................................... 4 

2. Problem Formulation ................................................................................................................. 4 

2.1. Nature of Regulatory Action................................................................................................ 4 

2.2. Previous Risk Assessments.................................................................................................. 4 

3. Stressor Source and Distribution ............................................................................................... 6 

3.1. Mechanism of Action........................................................................................................... 6 

3.2. Overview of Pesticide Usage............................................................................................... 6 

3.3. Environmental Fate and Transport....................................................................................... 8 

3.3.1. Solubility....................................................................................................................... 9 

3.3.2. Mobility......................................................................................................................... 9 

3.3.3. Degradation................................................................................................................. 10 

4. Receptors.................................................................................................................................. 11 

4.1. Effects to Aquatic Organisms ............................................................................................ 12

4.2. Effects to Terrestrial Organisms ........................................................................................ 13

4.3. Incident Database Review.................................................................................................. 16 

4.4. Ecosystems Potentially at Risk .......................................................................................... 17

5. Assessment Endpoints ............................................................................................................. 18 

6. Conceptual Model.................................................................................................................... 18 

6.1. Risk Hypothesis ................................................................................................................. 18 

6.2. Conceptual Diagram .......................................................................................................... 19 

7. Analysis Plan ........................................................................................................................... 19 

7.1. Stressors of Concern .......................................................................................................... 20 

7.2. Measures of Exposure........................................................................................................ 20 

7.3. Measures of Effect ............................................................................................................. 21 

7.4. Integration of Exposure and Effects .................................................................................. 24 

7.5. Deterministic and Probabilistic Assessment Methods....................................................... 24 

7.6. Endangered Species Assessments...................................................................................... 24 

7.8. Preliminary Identification of Data Gaps............................................................................ 25 

7.8.1. Effects ......................................................................................................................... 25

7.8.2 Exposure 

8. References............................................................................................................................. 27 

8.1. Cited Studies and Documents ............................................................................................ 27 

8.2. Submitted Effects Studies.................................................................................................. 30 

Appendix A. The Risk Quotient Method and Levels of Concern................................................. 33 

Appendix B. Data Call-In Table for Propoxur............................................................................. 35 
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1. Purpose 

The purpose of this problem formulation is to provide an understanding of what is known about 

the environmental fate and ecological effects of the registered uses of propoxur. Propoxur is an 

N-methyl residual carbamate insecticide used to control ticks, fleas, and a variety of insects 

including crickets, ants, wasps, cockroaches and silverfish in and around industrial, commercial, 

and residential facilities. 

This document will provide a plan for analyzing data relevant to propoxur and for conducting 

environmental fate, ecological risk, and endangered species assessments for its registered uses. 

Additionally, this problem formulation is intended to identify data gaps, uncertainties, and 

potential assumptions used to address those uncertainties relative to characterizing the ecological 

risk associated with the registered uses of propoxur. 

2. Problem Formulation 

2.1. Nature of Regulatory Action 

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA, 1947), all pesticides 

distributed or sold in the United States generally must be registered by EPA. In determining 

whether a pesticide can be registered in the U.S., EPA evaluates its safety to non-target species 

based on a wide range of environmental and health effects studies. In 1996, FIFRA was 

amended by the Food Quality Protection Act, and EPA was mandated to implement a new 

program for the periodic review of pesticides, i.e., registration review (USEPA, 1996a). The 

registration review program is intended to ensure that, as the ability to assess risk evolves and as 

policies and practices change, all registered pesticides continue to meet the statutory standard of 

no unreasonable adverse effects to human health and the environment. Changes in science, 

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

review program, the Agency periodically reevaluates pesticides to make sure that as change 

occurs, products in the marketplace can be used safely. 

As part of the implementation of the new Registration Review program pursuant to Section 3(g) 

of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA, 1947), the Agency is 

beginning its evaluation of propoxur to determine whether it continues to meet the FIFRA 

standard for registration. This problem formulation for the environmental fate, ecological risk, 

and endangered species assessment chapter in support of the registration review will be posted in 

the initial docket opening the public phase of the review process. 

2.2. Previous Risk Assessments 

There are a number of previous risk assessments related to the uses of propoxur, however many 

of them provide only limited information. The national level risk assessment in the EFED 

Science Chapter for the Reregistration Eligibility Decision (RED; USEPA, 1996) serves as the 
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basis for this problem formulation. A cumulative human health risk assessment was finalized in 

2007 for the N-methyl carbamate class of insecticides which includes propoxur (USEPA, 2007). 

All other previous risk assessments date to 1991 and earlier, and provide limited information. 

The risk assessments from 1991 and before are listed below. 

• Section 3 New Use (S3NU) label review for the outdoor use of Boat Guard (USEPA 

1991) 

• Section 3 New Use label review for the outdoor use of Baygon (USEPA 1990) 

• Ecological effects chapter of the propoxur registration standard (USEPA 1987) 

• Section 18 Emergency Exemption for the use of Baygon 70 WP to control mosquitoes 

(USEPA 1983) 

• S3NU for the use of Grant’s Ant Trap and Grant’s Ant Control (USEPA 1978a) 

• S3NU for the use of Grant’s Ant Control – Jel (USEPA 1978b) 

• S3NU for the use of Chaucon around residences (USEPA 1977a) 

• S3NU for the use of Baygon 1.5 Emulsifiable, Baygon Spray Concentrate, and Baygon 

70WP for the control of houseflies and stable flies in livestock and animal barns (USEPA 

1977b) 

• S3NU for the use of Baygon 70WP an dBaygon MOS for the control of adult mosquitoes 

and the amendment of registration to the use of Baygon 70WP for adult mosquito control 

on alfalfa and grass (USEPA 1977c) 

• S3NU for the registration of SMCP Baygon 2% (USEPA 1977d) 

• S3NU for the amendment to registration of Baygon 2% in Barns (USEPA 1977e) 

• S3NU for the registration of Best Earwig and Sowbog Bait (USEPA 1977f) 

• S3NU for the registration of Antrol Ant Trap with Baygon (USEPA 1977g) 

• S3NU for the registration of Baygon 70% on alfalfa and pasture grass (USEPA 1977h) 

• S3NU for the registration of Chacon Ant, Spider and Roach Dust (USEPA 1977i) 

• S3NU for the registration of SMCP Baygon 2% Mole Cricket Bait (USEPA 1976) 

• S3NU for the registration of Baygon MOS Insecticide (USEPA 1975) 

The ecological risk assessment included in the propoxur RED was based on laboratory fate and 

ecotoxicological data submitted by the registrant in support of reregistration, data in publicly 

available literature, and incident reports of adverse effects on non-target organisms associated 

with the use of propoxur. The previous ecological risk assessments considered the parent 

chemical only. The primary environmental concerns identified in the 1996 RED were acute risks 

to birds and mammals. EFED did not have the tools with which to assess chronic risk to birds or 

mammals based on the granular bait application. Therefore, chronic risk to either birds or 

mammals was not assessed. 

Based on the results of the RED, a number of mitigation measures were suggested for 

consideration to address risks from the 2% bait application of propoxur. Only the first of these 

mitigation options appear on the various labels of propoxur products (see Table 2). The options 

included: 
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• Add an additional avian label precaution, e.g. “Birds and small mammals feeding on 

treated bait may be killed” 

• Label products for restricted-use classification 

• Limit the outdoor use to crack and crevice treatment (especially since the registrant has 

previously indicated in the Phase 3 Response that this is the way the product is applied 

outdoors) 

• Reduce the width of the band from the maximum allowable three feet, to a narrower 

band, i.e. 6 inches 

3. Stressor Source and Distribution 

3.1. Mechanism of Action 

 

Propoxur is an N-methyl carbamate non-systemic insecticide that is used to control a variety of 

pests including fleas, ticks, cockroaches, ants, wasps, crickets, silverfish, and other pest insects. 

Propoxur interferes with acetylcholinesterase, an essential enzyme in the transmission of signals 

in nerve cells. Exposure to propoxur results in the overexcitation of the nervous system and 

eventually death in fleas, ticks and other insects. There are no longer any agriculatural uses 

registered for propoxur, and most current uses are for indoor applications. 

3.2. Overview of Pesticide Usage 

Propoxur was originally introduced in the United States in 1959. It has 42 active Section 3 

registrations, 2 technical registrations and 3 intermediate formulations (Table 1). There are 

currently no new uses pending, no special local need registrations, and no emergency 

exemptions. During the propoxur product reregistration, 7 products were amended and 35 

products were reregistered. It is a residual carbamate insecticide registered for indoor 

institutional, industrial, and commercial applications with very limited outdoor applications. 

There are permitted uses in food handling establishments and food processing plants such as 

crack and crevice treatments only. The only outdoor uses include structural perimeter 

applications as well as liquid and aerosol spot treatments. There are no permitted agricultural 

uses for propoxur. 

Bait stations, aerosol sprays, and liquid spot application uses will not be assessed for 

environmental risk because they are not expected to lead to significant exposure in the 

environment. The remaining use pattern from currently registered labels, bait application, will 

be assessed since product labels have granular application directions that may lead to 

environmental exposure. Further details of this use pattern are listed in Table 2. The maximum 

single granular application rate for propoxur is 0.005 pounds of active ingredient per thousand 

square feet (lbs a.i./1K sq. ft) (EPA Reg. No. 499-518 and 655-802). The labels do not specify 

how many applications may be applied per year. 
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Table 1. Currently labeled outdoor uses of propoxur. 

EPA Reg. No. Product Name Percent Active 

Ingredient 

Type of Use 

422-18 BA-KIL 19.6 Spot treatment; general surface spray 

506-137 TAT Ant Trap 0.25 Bait application 

1663-32 Grants Kills Ants Ant Control 

with Baygon 

0.25 Bait application 

8730-49 Hercon Insectape High-Tech 

with Propoxur 

10 Surface treatment 

10807-48 Misty Wasp and Hornet Killer 0.5 Crack and crevice treatment; general surface 

spray 

45385-13 Chem-Tox Industrial Insect 

Spray Contains Baygon 

1 General surface spray 

47000-102 CT Crack and Crevice 0.5 General surface spray 

10807-4 Misty Anti-Crawl Residual 

Insecticide 

0.5 General surface spray 

45385-1 Chem-tox Roach and Ant Spray 

with Baygon 

0.5 Surface treatment; crack and crevice 

treatment 

499-501 Brand 224B Residual 

Insecticide 

1 Crack and crevice treatment; spot treatment 

6218-24 Summit Permacide Plus 1 General surface spray 

10807-85 Misty Ant, Roach, and Spider 

Residual Insecticide 

1 General surface spray 

84396-12 Sungro Residual Spray 1 General surface spray; perimeter treatment 

655-546 Prentox Prenbay 1% Oil 

Solution 

1 General surface spray 

655-796 Prentox Prenbay 1.5 EC 19.6 General surface spray; spot treatment 

1021-1730 Pyrocide Pressurized Ant and 

Roach Spray 70451 

0.5 Perimeter treatment 

13283-26 Rainbow Insect Tag 9.4 Equipment treatment 

499-518 Prentox Larva-Lur contains 

Propoxur 

2 Bait application; crack and crevice treatment

84396-18 Sungro Residual Spray 0.5 General surface spray; spot treatment 

655-802 Prentox Larva-Lur contains 

Propoxur 

2 Bait application; crack and crevice treatment

Usage data provided to the Biological and Economic Analysis Division (BEAD) of the Office of 

Pesticide Programs for propoxur indicates that it is a minor use chemical in the professional pest 

management sector, accounting for <1% of the total chemicals applied each year (8,000 and 

9,000 lbs applied in 2001 and 2003, respectively). The lack of other usage data precludes an 

accurate assessment of the extent of total propoxur use. 
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Table 2. Labeled maximum use patterns for granular applications. 

Use Pattern EPA Reg. 

No. 

App. Rate 

(lbs a.i./ 

1K ft2)

No. App. 

per Year 

App. 

Method 

Restrictions 

Bait 

application 

499-518 0.005 Not 

Specified 

Granular 

broadcast 

in a 2-3 ft 

width band

- Label language: This product is toxic to 

fish, birds and wildlife. Birds and other 

wildlife in treated in treated areas may be 

killed. Do not apply directly to water, to 

areas where surface water is present or to 

intertidal areas below the mean high water 

mark. Do not apply where runoff is likely to 

occur. Do not contaminate water by cleaning 

of equipment or disposal of equipment 

washwaters. Apply this product only as 

specified on this label. 

- For outdoor use around patios, driveways, 

sidewalks, and foundations only 

Bait 

application 

655-802 0.005 Not 

Specified 

Granular 

broadcast 

in a 2-3 ft 

width band

-Label language: This product is toxic to 

wildlife and aquatic invertebrates. Birds and 

other small mammals feeding on treated bait 

may be killed. Do not apply directly to 

water. Do not apply where runoff is likely to 

occur. Do not contaminate water by cleaning 

of equipment or disposal of wastes. Apply 

this product only as specified on this label. 

-Use only around patios, driveways, 

sidewalks, and foundations. 

3.3. Environmental Fate and Transport 

For the currently registered uses of propoxur, the Agency typically requires an abbreviated set of 

environmental fate data on hydrolysis, metabolism, and mobility. Only supplemental data are 

available for propoxur. While shortcomings in the studies preclude a comprehensive assessment 

of the environmental fate of propoxur, a general assessment can be made. 

Based on supplemental data, propoxur is likely to be moderately persistent (the metabolic halflife is on the order of several months), mobile, and may potentially leach to groundwater. It is 

apparently hydrolytically stable at acid to neutral pHs (3 to 7) but degrades rapidly at alkaline pH 

values. The parent chemical appears susceptible to photolysis in water but not on soil. However, 

the intensity of light in the studies did not reflect that of natural sunlight. Aerobic and anaerobic 

soil metabolism half-lives are on the order of several months. Degradate characterization was 

incomplete in these studies. Laboratory mobility studies indicate that propoxur is very mobile 

(Kd values less than 1). Propoxur exhibits fate and transport characteristics similar to chemicals 

that are known to leach to groundwater. 

Well-designed, scientifically-valid studies could result in changes in the overall assessment, 

particularly in relation to persistence. For instance, photolysis may play a role in degradation of 

propoxur applied outdoors. However, considering the nature of the listed outdoor uses, additional 
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studies are not required at this time. The limited data available only support the uses discussed in 

this document. Any additional uses will require data to support them. 

3.3.1. Solubility 

CAS #: 114-26-1 

H20 solubility: 2,000 mg/l at 20-25 degrees C (U.S. Environmental Protection 

Agency. 1984); 1,750 ppm at 20 degrees C (Berg, G. L., 1986) 

Solubility in other 

solvents: 

soluble in organic polar solvents, readily soluble in acetone 

(American Conference of Governmental Industrial Hygienists, 

Inc. 1986); soluble in methanol, acetone, and many other 

organic solvents but only slightly soluble in cold hydrocarbons 

(Hayes, W. J. 1982). 

Melting Point: 81 degrees C (Berg, G. L., 1986) 

Vapor pressure: 6.5 x 10 to the minus 6 mmHg at 20 degrees C (Hayes, W. J. 

1982); 1 x 10 to the minus 6 mmHg at 120 degrees C 

(Worthing, C. R., 1983) 

Bioconcentration 

factor: 

9 (calculated from water solubility by regression equations) 

(TOXNET. 1986) 

Kow: log Kow = 1.45 (U.S. Environmental Protection Agency. 1986) 

Koc: 67 (calculated from water solubility by regression equations) 

(TOXNET. 1986) 

Partitioning Model: PCMC1 (mole fraction) 1.72 x 10 to the minus 4; PCMC2 

(mg/l) 2,000; PCMC3 (mcm/l) 9,600 (U.S. Environmental 

Protection Agency. 1984) 

Chemical Class/Use: methyl carbamate insecticide 

3.3.2. Mobility 

Leaching & adsorption/desorption (163-1) 

In soil thin-layer mobility studies on six soils, propoxur was found to be mobile, with R values of 

0.70 to 0.89 (MRID 0029887). 

In batch equilibrium studies, propoxur was very mobile, with Freundlich K values of 0.05 (sandy 

loam), 0.30 (silt loam), and 0.27 (silty clay). Koc values, calculated from the Kd and organic 

carbon (from organic d matter) data supplied in the report, were 3.4 (sandy loam), 11.2 (silt 

loam), and 102.6 (silty clay) (MRID 0085770). 

After 28 days of aerobic incubation in a silt loam soil, propoxur was found to be mobile in 12-

inch soil columns. The leachate contained 69 to 74% of the applied radioactivity after 100 ml of 

water was applied over a 45 day period (MRID 0085769). 
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(3) Field Dissipation 

Terrestrial field dissipation (164-1) 

Rough data from 10 studies on the persistence of propoxur in several different soil types suggest 

that the chemical moves rapidly through all the soil profiles below the 12 inch sampling depth 

(MRID 0085772). 

Environmental fate data on aqueous and soil photolysis, aerobic and anaerobic soil metabolism, 

leaching and adsorption/desorption, and terrestrial field dissipation are not required to support 

the current uses for propoxur. New studies may be required if other outdoor uses are considered 

in the future. 

3.3.3. Degradation 

Hydrolysis (161-1) 

An open literature study of several carbamates found that propoxur was stable to hydrolysis at 

pH 3.0-7.0 but degraded at alkaline pH values. The half-life for hydrolysis was 16 days at pH 8, 

1.6 days at Ph 9, and 0.17 days at pH10 (MRID 0085762). 

Photodegradation in water (161-2) 

Propoxur degraded in neutral, aqueous solutions (5 ppm propoxur) with a half-life of 10 days 

without a photosensitizer and 0.7 days with an acetone sensitizer. The degradation half-life was 

41 days in the dark control. Compensating for hydrolysis effects, the unsensitized halflife was 

projected at 13 days. The major degradates were isopropoxy phenol, unidentified polar 

compounds, and CO. The artificial light source had an intensity less than that of natural sunlight 

in Kansas City, MO (800 u-watts/cm2 vs. 3300-4400 u-watts/cm2 at midday in summer (MRID 

0085763). 

Photodegradation in soil (161-3) 

Propoxur photodegraded on a pH 8.2 sandy loam soil with a half-life of 77 days (extrapolated 

beyond the 28 day study). After 28 days, propoxur comprised 75% of the applied radioactivity, 

unextracted residues 12%, and volatiles 10%. The artificial light source was the same as that 

used in the aqueous photolysis study (MRID 0085763). 

Aerobic soil metabolism (162-1) 

The degradation of Propoxur under aerobic conditions in silt loam and sandy loam soils followed 

first order kinetics for the first 112 and 180 days, respectively. The half-life values were 80 days 

for the silt loam and 210 days for the sandy loam. Propoxur was the major extractable residue 

found in the studies. CO (30% after 112 days; 35% after 336 days) and unextracted residues (up 
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to 40%) also comprised major portions of the applied radioactivity. The primary mode of 

degradation appears to be hydrolysis of the carbamate linkage (MRID 0085768). 

Anaerobic soil metabolism (162-2) 

Propoxur degraded in a silt loam soil under anaerobic conditions with a half life of 80 days, the 

same as found in the aerobic metabolism study above. The anaerobic half-life resulting from the 

flooding of a sandy loam that had been incubated aerobically for 30 days was 108 days. The halflife in sterile soils was the same as that measured in non-sterile soils (MRID 0085768). 

4. Receptors 

Consistent with the process described in the Overview Document (USEPA, 2004), the risk 

assessment for propoxur relies on a surrogate species approach. Toxicological data generated 

from surrogate test species, which are intended to be representative of broad taxonomic groups, 

are used to extrapolate to potential effects on a variety of species (receptors) included under 

these taxonomic groupings. 

Acute toxicity data from studies submitted by pesticide registrants along with the available open 

literature are used to evaluate the potential direct and indirect effects of propoxur to terrestrial 

receptors. Submitted data typically include toxicity information on the technical grade active 

ingredient, degradates, and when available, formulated products (e.g., “Six-Pack” studies). The 

open literature studies are identified through EPA’s ECOTOXicology (ECOTOX) database 

(USEPA, 2008a), which employs a literature search engine for locating chemical toxicity data 

for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data may also 

provide insight into the direct and indirect effects of propoxur on biotic communities from loss 

of species that are sensitive to the chemical and from changes in structure and functional 

characteristics of the affected communities. 

A complete search of the ECOTOX database for propoxur toxicity data was completed in June 

2009 and a large number of potentially relevant open literature papers for propoxur were 

identified. An evaluation of the ECOTOX open literature studies for possible quantitative and/or 

qualitative inclusion in the ecological risk assessment, including identification of open literature 

data that may be used to fill the large number of ecological effects data gaps, is expected to be 

completed prior to the docket opening for propoxur. Based on a preliminary review of the 

ECOTOX search, open literature data were identified for a number of taxonomic groups, 

including estuarine/marine fish, freshwater fish, mammals, invertebrates, and amphibians. 

Studies, though very limited in number, were also identified for both terrestrial and aquatic 

plants, for which no registrant-submitted data are available. The extent to which the open 

literature data can be used to fulfill these data gaps will be determined pending its review and 

evaluation. 

A summary of the aquatic and terrestrial toxicity data used to derive a preliminary evaluation of 

risk for propoxur is provided in Sections 4.1 and 4.2, respectively. In addition, a summary of 
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ecological incidents associated with propoxur and a description of ecosystems potentially at risk 

are provided in Sections 4.3 and 4.4, respectively. 

4.1. Effects to Aquatic Organisms 

A summary of the aquatic toxicity data from registrant-submitted studies is provided in Table 3. 

Propoxur was used in the aquatic testing. Propoxur is classified as moderately toxic to 

freshwater fish and very highly toxic to both freshwater and marine invertebrates on an acute 

exposure basis. Toxicity data for aquatic vascular and non-vascular plants are not available. 

Table 3. Summary of submitted aquatic toxicity studies for propoxur. 

Species 

(common name) 

% a.i. Endpoint 

(ppm) 

Acute 

Toxicity 

Classification 

Citation 

MRID/ 

Accession 

number 

Study 

Classification 

Oncorhynchus 

mykiss 

(Rainbow Trout) 

98.8 

3.7 

(acute 

LC50) 

Moderately 

toxic 

 00149171 

D. Lamb 1981 Acceptable 

Oncorhynchus 

mykiss 

(Rainbow Trout)

88 

8.2 

(acute 

LC50) 

Moderately 

toxic 

40098001 

Mayer and 

Ellersieck 1986 

Supplemental 

Lepomis 

macrochirus 

(Bluegill sunfish)

98.8 

6.2 

(acute 

LC50) 

Moderately 

toxic 

00149171 

D. Lamb 1981 Acceptable 

Lepomis 

macrochirus 

(Bluegill sunfish) 

88 

4.8 

(acute 

LC50) 

Moderately 

toxic 

40098001 

Mayer and 

Ellersieck 1986 

Supplemental 

Daphnia magna 

(Water Flea) 98.8 

0.011 

(acute 

EC50) 

Very highly 

toxic 00149172 

D. Lamb 1981 

Acceptable 
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Table 3. Summary of submitted aquatic toxicity studies for propoxur. 

Species 

(common name) 

% a.i. Endpoint 

(ppm) 

Acute 

Toxicity 

Classification 

Citation 

MRID/ 

Accession 

number 

Study 

Classification 

Daphnia magna 

(Water Flea)

98.5 

>0.051 

(21 day 

LC50)

N/A 41425301 

D. Surprenant Supplemental 

Pimephales 

promelus 

(Fathead 

minnow) 

88 

25 

(acute 

LC50) 

Slightly toxic 

40098001 

Mayer and 

Ellersieck 1986 

Supplemental 

Gammarus 

lacustris

(Amphipod) 

88 

0.034 

(acute 

LC50) 

Very highly 

toxic 

40098001 

Mayer and 

Ellersieck 1986 

Supplemental 

Pteronarcys 

(Stonefly) 

88 

0.18 

(acute 

LC50) 

Highly toxic 

40098001 

Mayer and 

Ellersieck 1986 

Supplemental 

Oyster 100 

>1 

(96-hour 

EC50) 

Moderately 

toxic 

40228401 

Mayer 1986 Supplemental 

Sheepshead 

minnow

100 

>1 

(48-hour 

LC50) 

Moderately 

toxic 

40228401 

Mayer 1986 Supplemental 

Penaeus 

duoraum 

(Pink shrimp)

100 

0.041 

(48-hour 

LC50) 

Very highly 

toxic 

40228401 

Mayer 1986 Supplemental 

Scenedesmus 

subspicatus

(Green Algae) 

Technical ECx - 158414 Not yet reviewed 

4.2. Effects to Terrestrial Organisms 

Available data on the toxicity of propoxur to terrestrial animals are summarized in Tables 4 and

5. Data for terrestrial plant toxicity are not available for propoxur. 

Propoxur is classified as moderately toxic to mammals and very highly toxic to birds on an acute 

oral basis and also highly toxic to birds on a sub-acute dietary exposure basis. In addition, 

propoxur is highly toxic to honey bees (Apis mellifera) on an acute contact exposure basis. 
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Table 4. Summary of endpoints from submitted terrestrial animal acute toxicity studies for propoxur. 

Species 

(common 

name)

% a.i. End-point Acute Toxicity 

Classification 

Citation 

MRID / Accession 

number

Study 

Classification

Canada goose 87 

5.95 

(mg/kg bwt) 

Very highly 

toxic 

00160000 

Hudson et al. 1984 Supplemental1

Mallard 98 

9.44 

(mg/kg bwt) 

Very highly 

toxic “ ” “ ” 

Sharp-tailed 

grouse 

97 

120 

(mg/kg bwt) 

Moderately 

toxic “ ” “ ” 

California 

quail 

97 

25.9 

(mg/kg bwt) Highly toxic “ ” “ ” 

Japanese quail 97 

28.3 

(mg/kg bwt) Highly toxic “ ” “ ” 

Pheasant 98 

20 

(mg/kg bwt) Highly toxic “ ” “ ” 

Chukar 98 

25.8 

(mg/kg bwt) Highly toxic “ ” “ ” 

Sandhill crane 98 

60.4 

(mg/kg bwt) 

Moderately 

toxic “ ” “ ” 

Rock dove 97 

60.4 

(mg/kg bwt) 

Moderately 

toxic “ ” “ ” 

House 

sparrow 

97 

12.8 

(mg/kg bwt) Highly toxic “ ” “ ” 

Mourning 

dove 

97 

4.2 

(mg/kg bwt) 

Very highly 

toxic “ ” “ ” 

House finch 97 

3.55 

(mg/kg bwt) 

Very highly 

toxic “ ” “ ” 

Dark-eyed 

junco 

97 

4.76 

(mg/kg bwt) 

Very highly 

toxic “ ” “ ” 

Bobwhite 

quail 

2 

(Formulated 

product - bait) 

23 

(mg a.i./kg basis) 

1005 

(formulated 

product basis) 

Highly toxic 41625101 

Campbell et al. 1990 Acceptable 
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Table 4. Summary of endpoints from submitted terrestrial animal acute toxicity studies for propoxur. 

Species 

(common 

name)

% a.i. End-point Acute Toxicity 

Classification 

Citation 

MRID / Accession 

number

Study 

Classification

Northern 

bobwhite 

quail 

Technical % 

unknown 

2828 

(ppm) Slightly toxic 

42757101 

42301201 

00149015 

Lamb 1981 

Supplemental2

Mallard duck 98.8 

>5000 

(ppm) 

Practically 

non-toxic 

42757102 

42301202 

00149014 

Lamb 1981 

“ ” 

Northern 

bobwhite 

quail

Technical % 

unknown 

206 

(ppm) Highly toxic 

00022923 

Hill et al. 1975 Supplemental3

Japanese quail Technical % 

unknown 

>5000 

(ppm) 

Practically 

non-toxic “ ” “ ” 

Ring-necked 

pheasant

Technical % 

unknown 

Approx. 1750 

(ppm) Slightly toxic “ ” “ ” 

Mallard Technical % 

unknown 

<1000 

(ppm) 

Moderately 

toxic “ ” “ ” 

Rattus 

norvegicus

(Laboratory 

rat) 

Technical 

94 mg/kg (M) 

68 mg/kg (F) 

(oral LD50) 

- 00152443 - 

Rabbit Technical > 2000mg/kg 

(Dermal LD50) - 40836401 - 

Rattus 

norvegicus

(Laboratory 

rat) 

Technical 

> 0.498 mg/L 

(Acute Inhalation 

LC50) 

- 40836402 - 

Rattus 

norvegicus

(Laboratory 

rat) 

99.8 

>80 ppm 

reproductive 

effect NOEC (2 

generation 

reproduction) 

No 

reproductive 

toxicity was 

observed at 

levels up to 80 

ppm in diet 

42615403 - 

Apis mellifera

(Honey Bee)

Not reported 

1.35 

(LD50) Highly toxic 

00036935 

Atkins et al. 1975 

Core4
-16 of 38- 

Table 4. Summary of endpoints from submitted terrestrial animal acute toxicity studies for propoxur. 

Species 

(common 

name)

% a.i. End-point Acute Toxicity 

Classification 

Citation 

MRID / Accession 

number

Study 

Classification

1 These studies are classified as supplemental. The USDI data are derived from scientifically sound studies that 

have been used to fulfill the guideline requirements in previous assessments. 

2 These studies are classified supplemental and not upgradeable (see memos A. Maciorowski to N. Kotey dated 

1/27/93 and A. Maciorowski to K. Davis dated 9/21/93). The mallard study is supplemental because only two 

treatment levels were employed and the age of the birds (13 days) was higher than the recommended 5-10 day 

age; also Miles was not able to adequately respond to a discrepancy between Hill’s mallard LC50 value of 

<1000ppm and Lamb’s LC50 value of >5000ppm. The bobwhite study continues to be classified supplemental 

because of study deficiencies listed in the DER and because Miles was unable to adequately explain the large 

discrepancy between Hill’s LC50 value of <206ppm and Lamb’s LC50 value of 2828ppm. 

3 Although the actual % ai was not reported, it is assumed it was greater than 95%. 

4 This study has been classified as scientifically sound and has been used to fulfill the guideline requirements in 

previous assessments. Although the actual % ai was not reported, it is assumed that it was greater than 95%. 

Table 5. Summary of endpoints from submitted terrestrial animal chronic toxicity studies for propoxur. 

Species 

(common 

name)

% a.i. End-point 

Acute 

Toxicity 

Classification 

Citation 

MRID / Accession 

number 

Study 

Classification 

Colinus 

virginianus 

(Northern 

bobwhite 

quail) 

98 

>320 ppm, 

highest dose 

tested 

- 

00149017 

D. Lamb and M. 

Carsel 1982 

Supplemental1

Anas 

platyrhynchos

(Mallard duck) 

98 80 ppm/320 ppm 

Reduced egg 

production and 

embryo 

viability 

00149016 

J. Carlise and M. 

Carlise 1982 

Supplemental2

1 This study is reclassified supplemental because a NOEC for reproductive effects was not established. The 

NOEC for brain cholinesterase inhibition was 80 ppm. 

2 This study is classified supplemental because the raw data were not provided to allow statistical verification 

of the results. 

4.3. Incident Database Review 

A preliminary review on August 12, 2009, of the Ecological Incident Information System (EIIS, 

version 2.1, USEPA, 2008b), which is maintained by the Agency’s Office of Pesticide Programs, 

and the Avian Monitoring Information System (AIMS), which is maintained by the American 
-17 of 38- 

Bird Conservancy, indicates a total of three reported ecological incidents associated with the use 

of propoxur. 

All of the propoxur incidents were classified as highly probably and a result of intentional 

misapplication, and they occurred between 1992 and 2000. All of the propoxur incidents 

involved birds. All of the incidents involved additional chemicals besides propoxur. The 

reported incidents for propoxur involved uses in which the product was not specified. While 

these products do not appear to be currently registered, similar granular bait products are 

currently registered. 

In addition to the incidents recorded in EIIS, additional incidents have been reported to the 

Agency in aggregated incident reports. Pesticide registrants report certain types of incidents to 

the Agency as aggregate counts of incidents occurring per product per quarter. Ecological 

incidents reported in aggregate reports include those categorized as “minor fish and wildlife” 

(W-B), “minor plant” (P-B), and “other nontarget” (ONT) incidents. “Other nontarget” incidents 

include reports of adverse effects to insects and other terrestrial invertebrates. For propoxur, 

registrants have reported 13 minor plant incidents but no minor fish and wildlife incidents or 

other nontarget incidents. 

In the risk assessment, the incidents will be further evaluated to determine if the reported 

incidents represent current patterns of use for propoxur. Examples of additional considerations 

are mitigation (e.g., reduced application rates), product cancellations, and changes in use patterns 

that have occurred since the date of the reported incidents. 

Although incident reports for propoxur have not been received by the Agency since 2000 and 

only three incidents have been reported to the Agency, the absence of reported incidents should 

not be construed as the absence of incidents. Incident reports for non-target organisms typically 

provide information only on mortality events and plant damage incidents. Except for phytotoxic 

effects in terrestrial plants, sublethal effects, such as reduced growth or impaired reproduction, 

are rarely reported. EPA’s changes in the registrant reporting requirements for incidents in 1998 

may account for a reduced number of reported incidents. Registrants are now only required to 

submit detailed information on ‘major’ fish, wildlife, and plant incidents. Minor fish, wildlife, 

and plant incidents, as well as all other nontarget incidents, are generally reported aggregately 

and are not included in EIIS. In addition, there have been changes in state monitoring efforts due 

to lack of resources. However, the incident data that are available suggest that exposure 

pathways for propoxur are complete and that exposure levels are sufficient to result in fieldobservable effects. 

4.4. Ecosystems Potentially at Risk 

The ecosystems at risk are often extensive in scope; therefore, it may not be possible to identify 

specific ecosystems during the development of a nation-wide ecological risk assessment. 

However, in general terms and based on the usage pattern of propoxur, terrestrial ecosystems are 

potentially at risk and would include the treated area. 
-18 of 38- 

Due to the use patterns and relatively low usage of propoxur, EFED does not believe that aquatic 

exposure to propoxur will pose a risk to non-target organisms. The majority of propoxur uses 

are indoors, and usage data from the Biological and Economic Analysis Division (BEAD) of the 

Office of Pesticide Programs suggests that propoxur is a minor use chemical. The majority of 

uses are spot treatments with no agricultural uses. The previous Science Chapter of the RED in 

1996 modeled aquatic exposure from the propoxur impregnated tape that could be attached to 

boat mooring lines. This use, however, has been cancelled and no other uses appear to be a 

significant route of aquatic exposure. Therefore, based on the limited outdoor uses and relatively 

low usage, OPP will not be doing either an aquatic ecological assessment or a human health 

drinking water assessment for propoxur. 

5. Assessment Endpoints 

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (species, community, or other entity) and its attribute or characteristics 

(USEPA, 1998). For propoxur, the ecological entities may include the following: birds, 

mammals, terrestrial-phase amphibians, reptiles, terrestrial plants, and insects. The attributes for 

each of these entities may include growth, reproduction, and survival. 

6. Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure. 

The conceptual model for propoxur provides a written description and visual representation of 

the predicted relationships between propoxur, potential routes of exposure, and the predicted 

effects for the assessment endpoint. A conceptual model consists of two major components: a 

risk hypothesis and a conceptual diagram, which are discussed below (USEPA, 1998). 

6.1. Risk Hypothesis 

A risk hypothesis describes the predicted relationship among the stressor, exposure, and 

assessment endpoint response along with the rationale for their selection. For propoxur, the 

following ecological risk hypothesis is being employed for this ecological risk assessment: 

Based on the application methods and available toxicity data for non-target terrestrial 

species, propoxur has the potential to reduce survival, reproduction, and/or growth in 

non-target birds, mammals, terrestrial phase amphibians and reptiles, and beneficial 

subterranean insects when used in accordance with the current labels. These non-target 
-19 of 38- 

organisms include federally listed threatened and endangered species as well as nonlisted species.

6.2. Conceptual Diagram 

Based on the usage patterns of propoxur, granular bait applications represent potential transport 

mechanisms of propoxur to terrestrial habitats where non-target organisms may be exposed. 

Other terrestrial uses (e.g. spot spray, aerosol, and bait trap applications) will not be assessed 

because they are not expected to be significant routes of exposure and EFED does not currently 

have exposure scenarios for these types of uses. The transport mechanisms (i.e., sources) of the 

2% granular bait application are depicted in the conceptual model below (Figure 2) along with 

the receptors of concern and the potential attribute changes in the receptors due to exposures to 

propoxur. 

Figure 2. Conceptual model for propoxur effects on terrestrial organisms. Dashed lines represent 

uncertainty from a lack of effects data.

7. Analysis Plan 

In order to address the risk hypothesis, the potential for adverse effects on the environment is 

estimated. The use, environmental fate, and ecological effects of propoxur are characterized and 

integrated to assess the risks. This is accomplished using a risk quotient (ratio of exposure 

concentration to effects concentration) approach. Although risk is often defined as the likelihood 

Stressor

Source

Receptors

Attribute 

Change

Propoxur (granular bait) applied to use site (Commercial and Residential Structures) 

Direct 

application

Terrestrial 

invertebrates

Terrestrial/riparian plants 

grasses/forbs, fruit, seeds 

(trees, shrubs)

Exposure 

Media

Birds / 

Mammals/Terrestrial 

phase 

amphibians/reptiles

Soil

Ingestion/Dermal Uptake

Birds / mammals / terrestrial 

amphibians / reptiles/ 

subterranean invertebrates 

Juvenile Adult

Ingestion

Ingestion

Habitat integrity 

Reduction in primary productivity

Reduced cover 

Community change Food chain 

Reduction in prey

Individual organisms 

Reduced survival 

Reduced growth 

Reduced reproduction
-20 of 38- 

and magnitude of adverse ecological effects, the risk quotient-based approach does not provide a 

quantitative estimate of likelihood and/or magnitude of an adverse effect. However, as outlined 

in the Overview Document (USEPA, 2004), the likelihood of effects to individual organisms 

from particular uses of propoxur is estimated using the probit dose-response slope and either the 

level of concern (discussed below) or the actual calculated risk quotient value. 

This analysis plan will be revisited and may be revised depending upon the review and 

evaluation of data available in the open literature and the information submitted by the public in 

response to the opening of the Registration Review docket. 

7.1. Stressors of Concern 

The focus of this assessment is the propoxur, and any environmental degradates will be screened 

for ecological risk concern using the available data. 

In its ecological risk assessments, the Agency does not routinely include an evaluation of 

mixtures of active ingredients, either those mixtures of multiple active ingredients in product 

formulations or those in the applicator’s tank. In the case of the product formulations of active 

ingredients (that is, a registered product containing more than one active ingredient), each active 

ingredient is subject to an individual risk assessment for regulatory decision regarding the active 

ingredient on a particular use site. If effects data are available for a formulated product 

containing more than one active ingredient, the data may be used qualitatively or quantitatively 

in accordance with the Agency’s Overview Document and the Services’ Evaluation 

Memorandum (USEPA, 2004; USFWS/NMFS, 1998). 

Available toxicity data for environmental mixtures of propoxur with other pesticides will be 

presented as part of the ecological risk assessment. It is expected that the potential toxic effect of 

propoxur, in combination with other pesticides used in the environment, is likely to be a function 

of many factors including but not necessarily limited to: (1) the exposed species, (2) the cocontaminants in the mixture, (3) the ratio of propoxur and co-contaminant concentrations, and 

(4) differences in the pattern and duration of exposure among contaminants. Quantitatively 

predicting the combined effects of all these variables on mixture toxicity to any given taxa with 

confidence is beyond the capabilities of the available data and methodologies. However, a 

qualitative discussion of implications of the available pesticide mixture effects data on the 

confidence of risk assessment conclusions will be addressed as part of the uncertainty analysis. 

7.2. Measures of Exposure 

In order to estimate risks of propoxur exposures in terrestrial environments, all exposure 

modeling and resulting risk conclusions will be made based on maximum application rates for 

the 2% granular bait use patterns listed in Table 2. Measures of exposure are based on terrestrial 

models that predict estimated environmental concentrations (EEC) of propoxur using maximum 

labeled application rates and methods, as well as any mitigation measures specifically indicated 
-21 of 38- 

on the label. The models used to predict terrestrial EECs on food items is the Terrestrial Residue 

EXposure model (T-REX) for mammals and birds and the Terrestrial Herptafaunal Exposure and 

Residue Program Simulation (T-HERPS). The model used to derive EECs relevant to terrestrial 

and wetland plants is TerrPlant. These models are parameterized using relevant reviewed 

registrant-submitted environmental fate data. 

Exposure estimates for terrestrial animals assumed to be in the target area or in an area exposed 

to spray drift are derived using the T-REX model (v1.3.1; Dec. 7, 2006). This model 

incorporates the Kenega nomograph, as modified by Fletcher et al. (1994), which is based on a 

large set of actual field residue data. The upper limit values from the nomograph represent the 

95th percentile of residue values from actual field measurements (Hoerger and Kenega, 1972). 

The Fletcher et al. (1994) modifications to the Kenega nomograph are based on measured field 

residues from 249 published research papers, including information on 118 species of plants, 121 

pesticides, and 17 chemical classes. 

Exposure estimates from granular applications for birds (and, thus, terrestrial-phase amphibians 

and reptiles), terrestrial subterranean invertebrates, and mammals assumed to be in the target 

area or in an area exposed to propoxur granules are derived using the T-REX model. T-REX 

includes the capability to calculate the LD50/ft2

 risk index values. Conceptually, an LD50/ft2 is the 

amount of a pesticide estimated to kill 50% of exposed animals in each square foot of applied 

area. Although a square foot does not have defined ecological relevance and any unit area could 

be used, risk presumably increases as the number of LD50s/ft2 increases. The LD50/ft2 is used to 

estimate risk for granular formulations and row, banded, and in-furrow applications. For 

additional information on the LD50/ft2 risk index, please reference U.S. EPA (1992). The 

LD50/ft2 is calculated using a toxicity value (adjusted LD50) and the EEC (mg a.i. ft-2) and is 

directly compared with the Agency's levels of concern (LOCs). 

The weight of each granule is also necessary information related to risk characterization in TREX for granular applications. T-REX provides information on the LD50/ft2

 based on the 

application rate of the granular formulation. In some cases, an animal may have to ingest large 

quantities of the pesticide, whereas in other cases the animal would only need to ingest a few 

granules to reach the adjusted LD50. The weight of each granule would therefore further refine 

the risk assessment by allowing the chemical reviewer to determine how many granules an 

animal would need to ingest to reach the adjusted LD50 and how probable the ingestion rate 

would be. This information should be obtained from the registrant in order to facilitate the risk 

assessment for terrestrial applications. 

7.3. Measures of Effect 

 

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

Data are obtained from registrant-submitted studies or from literature studies identified by 

ECOTOX. The ECOTOX database (USEPA, 2008a) provides more ecological effects data in an 

attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity 

data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. 

ECOTOX was created and is maintained by the USEPA, Office of Research and Development, 
-22 of 38- 

and the National Health and Environmental Effects Research Laboratory's Mid-Continent 

Ecology Division. A number of studies were identified in the open literature as acceptable 

according to OPP and EFED criteria through a search of the ECOTOX database. These studies 

are listed in Table 6. 

Information on the potential effects of propoxur on non-target animals is collected from the EIIS, 

which will also be incorporated into the assessment. The EIIS is a database containing adverse 

effect (typically mortality) reports on non-target organisms where such effects have been 

associated with the use of pesticides. This information will be used to assess the presence of 

toxic exposure to non-target organisms after propoxur application in the environment and the 

conditions under which the exposure occurred. 

Where available, sublethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects may include behavioral changes (e.g., 

lethargy and changes in coloration). Quantitative assessments of risks, however, are limited to 

those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired 

survival, growth and reproduction. 

The assessment of risk for direct effects to non-target organisms makes the assumption that 

toxicity of propoxur to birds is similar to terrestrial-phase amphibians and reptiles. The same 

assumption is made for fish and aquatic-phase amphibians. 

Table 6. Summary of endpoints from the open literature for propoxur. 

Species 

(common 

name)

% a.i. End-point 

Citation 

MRID/Ecotox 

Reference Number

Study 

Classification 

Oncorhynch

us mykiss 

(Rainbow 

Trout)

2 

(Formulated 

Product - bait) 

92 

(ppm acute LC50) 

44027705 

USEPA/McCann 

1975 

Supplemental 

Lepomis 

macrochirus 

(Bluegill 

sunfish)

Technical (% 

Unknown) 

6.1 

(ppm acute LC50) 

44027704 

USEPA/McCann 

1977 

Supplemental 

Lepomis 

macrochirus 

(Bluegill 

sunfish)

70 

(Formulated 

Product – 

wettable 

powder) 

9.0 

(ppm acute LC50) 

44027703 

USEPA/McCann 

1977 

Supplemental 

Lepomis 

macrochirus 

(Bluegill 

sunfish) 

2 

(Formulated 

Product - bait) 

>180 

(ppm acute LC50) 

44027702 

USEPA/McCann 

1975

Supplemental 
-23 of 38- 

Table 6. Summary of endpoints from the open literature for propoxur. 

Species 

(common 

name)

% a.i. End-point 

Citation 

MRID/Ecotox 

Reference Number

Study 

Classification 

Lepomis 

macrochirus 

(Bluegill 

sunfish) 

70 

(Formulated 

Product – 

wettable 

powder) 

3.55 

(ppm acute LC50) 

44027701 

USEPA/McCann 

1977

Supplemental 

Norway Rat 99.2 32.74 mg/kg 

(dietary LD50) 

110891 Not yet reviewed 

House 

Mouse 

98 

0.50 mg/kg 

(dietary chronic 

NOAEL) 

111332 Not yet reviewed 

Apis 

mellifera 

(Honey Bee) 

100 

0.112 

(acute contact 

LD50) 

67983 Not yet reviewed 

Rana 

catesbeiana 

(Bullfrog) 

97 

595 mg/kg bwt 

(acute dietary 

LD50) 

50386 Not yet reviewed 

Earthworm 10 

2 lbs a.i./acre 

(LOEL) 

67190 Not yet reviewed 

Soybean 100 4 oz a.i./cwt sd 103956 Not yet reviewed 

1 These studies are classified as supplemental. The USDI data are derived from scientifically 

sound studies that have been used to fulfill the guideline requirements in previous 

assessments. Although the actual % ai was not reported, it is assumed it was greater than 

95%. 

The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50. 

LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at once, that is 

estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” 

and LC50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. 

EC stands for “Effective Concentration” and the EC50 is the concentration of a chemical that is 

estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic 

measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and NOEC. 

NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest tested dose of 

a substance that has been reported to have no harmful (adverse) effects on test organisms. The 

NOAEC (i.e., “No-Observed-Adverse-Effect-Concentration”) is the highest test concentration at 

which none of the observed effects were statistically different from the control. The NOEC is 

the No-Observed-Effects-Concentration. For non-listed plants, only acute exposures are 
-24 of 38- 

assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed plants either the 

NOAEC or EC05 is used. 

 

7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects characterization to 

determine the potential ecological risk from the use of propoxur as a bait application and crack 

and crevice treatment around residential and commercial structures. The exposure and toxicity 

effects data are integrated in order to evaluate the risks of adverse ecological effects on nontarget species. For the assessment of propoxur risks, the risk quotient (RQ) method is used to 

compare exposure and measured toxicity values. EECs are divided by acute and chronic toxicity 

values. The resulting RQs are then compared to the Agency’s Levels of Concern (LOCs) 

(USEPA, 2004). These criteria are used to indicate when propoxur’s uses, as directed on the 

label, have the potential to cause adverse direct or indirect effects to non-target organisms. In 

addition, incident data from the EIIS will be considered as part of the risk characterization. 

 

7.5. Deterministic and Probabilistic Assessment Methods 

The quantitative assessment of risk will primarily depend on the deterministic point-estimate 

based approach described in the risk assessment. An effort will be made to further qualitatively 

describe risk using probabilistic tools that the Agency has developed. These tools have been 

reviewed by FIFRA Scientific Advisory Panels (http://www.epa.gov/scipoly/sap/index.htm) and 

have been deemed as appropriate means of refining assessments where deterministic approaches 

have identified risks. 

7.6. Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to Federally-listed threatened and/or endangered (listed) species from 

registered uses of propoxur during registration review. This assessment will be conducted in 

accordance with the Overview Document (USEPA, 2004), provisions of the ESA, and the 

Services’ Endangered Species Consultation Handbook (USFWS/NMFS, 1998). 

The assessment of effects associated with the registration of propoxur is based on an action area. 

The action area is considered to be the area directly or indirectly affected by the federal action, as 

indicated by the exceedance of Agency Levels of Concern (LOCs) used to evaluate direct or 

indirect effects. The Agency’s approach to defining the action area under the provisions of the 

Overview Document (USEPA, 2004) considers the results of the risk assessment process to 

establish boundaries for that action area with the understanding that exposures below the 

Agency’s defined LOCs constitute a no-effect threshold. For the purposes of this assessment, 

attention will be focused on the footprint of the action (i.e., the area where propoxur application 

occurs), plus all areas where offsite transport (i.e., spray drift, runoff, etc.) may result in potential 

exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the 
-25 of 38- 

action area for listed species include any direct and indirect effects and/or potential modification 

of its critical habitat, including reduction in survival, growth, and reproduction as well as the full 

suite of sublethal effects available in the effects literature. Therefore, the action area extends to a 

point where environmental exposures are below any measured lethal or sublethal effect threshold 

for any biological entity at the whole organism, organ, tissue, and cellular level of organization. 

In situations where it is not possible to determine the threshold for an observed effect, the action 

area is not spatially limited and is assumed to be the entire United States. 

7.8. Preliminary Identification of Data Gaps 

 7.8.1. Effects 

The ecological effects data set for propoxur contains a number of gaps for terrestrial and aquatic 

animals and plants (Tables 5 – 7). Data gaps include the following: avian acute dietary toxicity; 

avian reproductive toxicity, acute toxicity to saltwater fish, saltwater invertebrate acute toxicity, 

freshwater invertebrate life-cycle, and Tier I terrestrial and aquatic plant toxicity studies. Only 

terrestrial studies are being requested because EFED assumes that aquatic exposure will not be a 

significant source of risk based on the use patterns and usage of propoxur. Further information 

on ecological effects data required to fulfill the Agency’s guideline requirements for propoxur is 

presented as the Data Call-in (DCI) table in Appendix B. In addition to providing the guideline 

number and study title for required data, the DCI table provides a rationale for requiring the data, 

an explanation of how the data will be used, and a brief description of the how the data could 

impact the Agency’s future decision-making. 

Table 5. Ecological effects data for terrestrial animals exposed to propoxur and remaining data gaps.

Guideline Description MRID/ 

Accession 

Classification Data 

Gap? 

Comments 

00160000 Supplemental 850.2100 Avian oral toxicity 

41625101 Acceptable 

No - 

00149015 

00149014 Supplemental 

850.2200 Avian dietary 

toxicity 00022923 Supplemental 

Yes1

Studies submitted by the 

registrant were classified as 

supplemental but do not satisfy 

the guideline requirements for 

the bobwhite quail or mallard 

duck. 

00149017 Supplemental 

850.2300 Avian reproduction 

00149016 Supplemental 

Yes1

According to the 40 CFR part 

158, an avian reproduction 

study is required for a mallard 

duck and a bobwhite quail. 

850.3020 Honeybee acute 

contact toxicity 01006003 Acceptable No - 
-26 of 38- 

Table 6. Available ecological effects data for aquatic animals exposed to propoxur and remaining data gaps.

Guideline Description MRID/ 

Accession 

Classification Data 

Gap? 

Comments 

00149171 Acceptable 

40098001 Supplemental 

44027705 Supplemental 

44027704 Supplemental

44027703 Supplemental

04427702 Supplemental

44027701 Supplemental

850.1075 Freshwater fish – 

Acute toxicity 

40098001 Supplemental

No 

The registrant submitted study 

was classified as acceptable and 

provides data on both rainbow 

trout and bluegill fish. 

850.1075 Saltwater fish – 

Acute toxicity 40228401 Supplemental Yes2 

The study from Mayer 1986 is 

classified as supplemental but 

does not satisfy the guideline 

requirements. 

00149172 Acceptable 850.1010 

Freshwater 

invertebrates – 

Acute toxicity 40098001 Supplemental 

No - 

850.1025 

850.1035 

850.1045 

850.1055 

Saltwater 

invertebrates – 

Acute toxicity 

40228401 Supplemental Yes2

The study from Mayer 1986 is 

classified as supplemental but 

does not satisfy the guideline 

requirements. 

850.1300 

Freshwater 

invertebrate – 

life cycle test 

41425301 Supplemental Yes2

The reviewer classified the 

study as supplemental but 

stated that it did not meet the 

guideline criteria. 

850.1350 

Saltwater 

invertebrates – 

life cycle test 

N/A N/A CR 

Conditional data requirement 

based on the results of the acute 

saltwater invertebrate toxicity 

test. Data are generally not 

required for outdoor residential 

uses unless data indicate that 

pesticide residues from the 

proposed uses can potentially 

enter waterways.

850.1400 Freshwater fish – 

early life stage test N/A N/A CR 

Data are generally not required 

for outdoor residential uses 

unless data indicate that 

pesticide residues from the 

proposed uses can potentially 

enter waterways. 

850.1400 Saltwater fish – 

early life stage test N/A N/A CR 

Conditional data requirement 

based on the results of the acute 

saltwater fish toxicity test 

850.1500 Fish – 

life cycle test N/A N/A CR 

Conditional data requirement 

based on the results of the early 

life stage toxicity test 

CR = Conditionally required. 
-27 of 38- 

Table 7. Available ecological effects data for plants exposed to propoxur and remaining data gaps.

Guideline Description MRID/ 

Accession 

Classification Data 

Gap? 

Comments 

850.4100 

Terrestrial plant 

toxicity: Tier I 

seedling emergence 

None NA Yes1

850.4150 

Terrestrial plant 

toxicity: Tier I 

vegetative vigor 

None NA Yes1

Non-target terrestrial plant data 

are required at the Tier I level 

850.4400 Aquatic plant toxicity 

with Lemna spp. 

None NA Yes2 

850.5400 Aquatic plant toxicity 

with algae None NA Yes2 

Non-target aquatic vascular and 

non-vascular plant data are 

required at the Tier I level 

1 This study is anticipated to be required during registration review. 

2 EFED assumes that aquatic exposure will not be a significant source of risk based on the use patterns and usage of 

propoxur. Therefore, this study is not being required at this time. 

7.8.1 Exposure 

The environmental fate data set for propoxur contains a number of gaps. There is, however, no 

current need for environmental fate data as inputs to aquatic or terrestrial exposure assessment 

models. There is potential ecological risk from the use of propoxur in soil, but it is unlikely that 

this use will cause risk to aquatic organisms from either runoff or spray drift. OPP will therefore 

require environmental chemistry analytical methods for propoxur in soil but will not require 

them in water. New studies may be required if other outdoor uses are considered in the future. 

8. References 

8.1. Cited Studies and Documents 

American Conference of Governmental Industrial Hygienists, Inc. 1986. Documentation of the 

threshold limit values and biological exposure indices. Fifth edition. Cincinnati, OH: 

Publications Office, ACGIH. 

Berg, G. L., ed. 1986. Farm Chemicals Handbook. Willoughby, Ohio: Meister Publishing Co. 

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the 

EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on 

plants. Environ. Tox. Chem. 13:1383-1391. 

Hayes, W. J. 1982. Pesticides studied in man. Baltimore, MD: Williams and Wilkins 

Hoerger, F. and E. E. Kenaga, 1972. Pesticide Residues on Plants: Correlation of Representative 

Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston and 
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F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and 

Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28. 

TOXNET. 1986. National library of medicine's toxicology data network. Hazardous Substances 

Databank. Public Health Service. National Institute of Health. U.S. Department of Health 

and Human Services. Bethesda, MD: NLM. 

USEPA. 1975. Ney, Ronald E Jr. Registration – Baygon MOS Insecticide. File No. 2075270 

U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. August 13, 1975. 

USEPA. 1976. Ney, Ronald E Jr. For use on mole cricket bait on lawn, golf courses, 

ornamental turfs, and pastures. U.S. Environmental Protection Agency, Office of 

Pesticide Programs, Environmental Fate and Effects Division. August 4, 1976. 

USEPA. 1977a. Cook, N. Registration for Use around the house. File No. 5719-AA. U.S. 

Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and 

Effects Division. January 18, 1977. 

USEPA. 1977b. Windberg, L.A. Amendment to Registration. File No. 3125-214, 3125-122, 

3125-146. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. November 23, 1977. 

USEPA. 1977c. Windberg, L.A. and R.W. Holst. Amendment to Registration to Alfalfa and 

Pasture grass and Registration. File No. 3125-146 and 3125-GNA. U.S. Environmental 

Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects 

Division. November 22, 1977. 

USEPA. 1977d. Sanders, F. Registration of SMCP Baygon 2% Mole Cricket Bait Insecticide. 

File No. 6720-EAU. U.S. Environmental Protection Agency, Office of Pesticide 

Programs, Environmental Fate and Effects Division. January 13, 1977. 

USEPA. 1977e. Windberg, Lamar A. Amendment to Registration – Barns. File No. 2075281. 

U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. November 23, 1977. 

USEPA. 1977f. O’Brien, Thomas F. Registration-Best Earwig and Sowbog Bait. File No. 

2075278. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. August 5, 1977. 

USEPA. 1977g. Ney, Ronald E Jr. Registration for control of ants, including fire ants + 

carpenter ants. File No. 2075277. U.S. Environmental Protection Agency, Office of 

Pesticide Programs, Environmental Fate and Effects Division. February 17, 1977. 
-29 of 38- 

USEPA. 1977h. Ney, Ronald E Jr. For use on alfalfa and pasture grass to control mosquitoes. 

File No. 2075279. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. September 21, 1977. 

USEPA. 1977i. Cook, Norman J. Registration for Use around the house. File No. 2075274. 

U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental 

Fate and Effects Division. January 18, 1977. 

USEPA. 1978a. Craven, Henry T. Registration – Ant Trap. Acc No. 094546. U.S. 

Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and 

Effects Division. October 6, 1978. 

USEPA. 1978b. Tice, John. Registration of New Product – Grant’s Ant Control-Jel. Acc No. 

232459. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. October 27, 1978. 

USEPA. 1983. Balcomb, R. Proposed Section 18 for use over flowing water to control 

mosquitoes. File No. 83-CA-76. U.S. Environmental Protection Agency, Office of 

Pesticide Programs, Environmental Fate and Effects Division. July 8, 1983. 

USEPA. 1987. Noles, John. Propoxur Registration Standard. Record No. 2075291 U.S. 

Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and 

Effects Division. May 5, 1987. 

USEPA. 1990. Felthousen, R.W. Amendment-Label Revision-Data Required. DP Barcode 

154393. U.S. Environmental Protection Agency, Office of Pesticide Programs, 

Environmental Fate and Effects Division. August 15, 1990. 

USEPA. 1991. Rexrode, Miachel. Label Review for Registration. File No. 62451-R. U.S. 

Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and 

Effects Division. January 24, 1991. 

USEPA.1996a.Food Quality Protection Act. http://www.epa.gov/oppsrrd1/registration_review/ 

USEPA. 1996b. Reregistration Eligibility Document for Propoxur, Science Chapter. U.S. 

Environmental Protection Agency, Office of Pesticide Programs. July 10, 1996. 

USEPA. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of 

Research and Development, Washington, D.C. EPA/630/R-95/002F. April 1998. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759 

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004. 
-30 of 38- 

USEPA. 2006. N-methyl Carbamate Revised Cumulative Risk Assessment. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic 

Substances, Office of Pesticide Programs, Washington DC. September 24, 2007. 

USEPA. 2008a. ECOTOXicology Database. Office of Research and Development National 

Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent 

Ecology Division (MED). June 30, 2008. http://cfpub.epa.gov/ecotox/ 

USEPA. 2008b. Ecological Incident Information System. June 24, 2008. 

http://www.epa.gov/espp/consultation/ecorisk-overview.pdf 

U.S. Environmental Protection Agency. 1986 (Jan). Estimating pesticide sorption coefficients for 

soils and sediments. Richard E. Green and Samuel W. Karickhoff. Environmental 

Research Laboratory. Office of Research and Development. Athens, GA. 

U.S. Environmental Protection Agency. 1984 (Dec.). User's manual for the pesticide root zone 

model (PRZM). Release 1. Athens, GA: Environmental Research Laboratory. 

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation 

and Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. 

March 1998. 

Worthing, C. R., ed. 1983. The pesticide manual: A world compendium. Croydon, England: The 

British Crop Protection Council. 

8.2. Submitted Effects Studies 

MRID: 00022923. Hill, E.F.; Heath, R.G.; Spann, J.W.; et al. (1975) Lethal Dietary Toxicities of 

Environmental Pollutants to Birds: Special Scientific Report--Wildlife No. 191. (U.S. 

Dept. of the Interior, Fish and Wildlife Service, Patuxent Wildlife Research Center; 

unpublished report). 

MRID: 00036935. Atkins E.L.; E.A. Greywood, and R.L. Macdonald. 1975. Toxicity of 

pesticides and other agricultural chemicals to honey bees. Laboratory studies. University 

of California, Division of Agricultural Sciences. Leaflet 2287. 38p. 

MRID: 00149014. Lamb, D. (1981) Acute Dietary LC50 of Technical Propoxur (Baygon) to 

Mallard Ducks: Study No. 80-175-10: Mobay Report No. 69609. Unpublished study 

prepared by Mobay Chemical Corp. 10 p. 

MRID: 00149015. Lamb, D. (1981) Acute Dietary LC50 of Technical Propoxur (Baygon) to 

Bobwhite Quail: Study No. 80-175-06: Mobay Report No. 80046. Unpublished study 

prepared by Mobay Chemical Corp. 9 p. 
-31 of 38- 

MRID: 00149016. Carlisle, J.; Carsel, M. (1982) Propoxur Reproduction Study with Mallard 

Duck: Study No. 81-675-06: Mobay Report No. 82265. Un- published study prepared by 

Mobay Chemical Corp. 55 p. 

MRID: 00149017. Lamb, D.; Carsel, M. (1982) Propuxur Reproduction Study with Bob- white 

Quail: Study No. 81-675-04: Mobay Report No. 82269. Un- published study prepared by 

Mobay Chemical Corp. 58 p. 

MRID: 00149171. Lamb, D. (1981) Acute Toxicity of Technical Propoxur (Baygon) to Bluegill 

and Rainbow Trout: Study Nos. 81-066-02 and 80-066-11. Unpublished study prepared 

by Mobay Chemical Corp. 9 p. 

MRID: 00149172. Lamb, D. (1981) Acute Toxicity of Technical Propoxur (Baygon) to Daphnia 

magna: Study No. 81-067-01. Unpublished study prepared by Mobay Chemical Corp. 9p. 

MRID: 00152443. Flucke, W. (1980) Boe 5812315 (Propoxur) Acute Toxicity Studies: Report 

No: 9295. Unpublished study prepared by Bayer AG. 7 p. 

MRID: 00158414. Heimbach, F. (1985) Growth Inhibition of Green Algae (Scenedesmus 

subspicatus) by Propoxur (Technical): Report HBF/A106. Unpub- lished Mobay Report 

No. 89080 prepared by Bayer AG. 18 p. 

MRID: 00160000. Hudson, R.H., R.K. Tucker and M.A. Haegele. (1984) Handbook of toxicity 

of pesticides to wildlife. USDI Resource Publication No. 153. Washington, DC. 92 pp. 

MRID: 40228401. Mayer, F.L. (1986) Acute toxicity handbook of chemicals to estuarine 

organisms. USEPA, Environmental Research Lab, Gulf Breeze, FL. EPA/600/X-86/231. 

275 pp. 

MRID: 40098001. Mayer, F.L. and M.R. Ellersieck. (1986) Manual of acute toxicity: 

Interpretation and data base for 410 chemicals and 66 species of freshwater animals. 

USDI, FWS Publication 160, Washington, DC. 506 p. 

MRID: 40836401. Sheets, L. (1988) Acute Dermal Toxicity of Technical Grade Baygon in 

Rabbits: Study No. 88-023-AQ. Unpublished study prepared by Mobay Corp. 19 p. 

MRID: 40836402. Pauluhn, J. (1988) Study of the Acute Inhalation Toxicity in Accor- dance 

with OECD Guideline No. 403: BOQ 5812315 (Propoxur): Re- port No. 98291. 

Unpublished study prepared by Bayer AG. 83 p. 

MRID: 41425301. Surprenant, D. (1988) The Chronic Toxicity of Technical Grade Propoxur 

(TradeName Baygon) to Daphnia magna under Flow-through Conditions: Final Report: 

Final Report: Report #87-7-2474: SLS Study #274.0986.6123/130. Unpublished study 

prepared by Spring- born Life Sciences. 47 p. 
-32 of 38- 

MRID: 41625101. Campbell, S. (1990) An Acute Oral Toxicity Study with the Northern 

Bobwhite: Baygon 2% Bait (Encapsulated): Lab Project Number: 149-159: 100240. 

Unpublished study prepared by Wildlife Intern- ational Ltd. 21 p. 

MRID: 42615403. Dotti, A.; Kinder, J.; Biedermann, K.; et al. (1992) Two-generation 

Reproduction Study in Rats: BOQ 5812315: Lab Project Number: 286997: T 5039706. 

Unpublished study prepared by Research & Consulting Co. Ltd. and Biological Research 

Labs Ltd. 734 p. 

MRID: 44027701. US EPA (1977) Biological Report of Analysis: Baygon 70% Wettable 

Powder: Brook Trout (Salvelinus fontinalis): Static Jar Test 1106. Unpublished study. 1p. 

MRID: 44027702. US EPA (1975) Report of Analysis: Baygon 2% Bait Insecticide: Bluegill: 

(Lepomis macrochirus): Static Jar Test 883. Unpublished study. 1 p. 

MRID: 44027703. US EPA (1977) Biological Report of Analysis: Baygon 70% Wettable 

Powder: Bluegill (Lepomis macrochirus): Static Jar Test 1115. Unpublished study. 1 p. 

MRID: 44027704. US EPA (1977) Biological Report of Analysis: Baygon Technical: Bluegill 

(Lepomis macrochirus): Static Jar Test 1119. Unpublished study. 1 p. 

MRID: 44027705. US EPA (1975) Report of Analysis: Baygon 2% Bait Insecticide: Rainbow 

Trout (Salmo gairdneri {Oncorhynchus mykiss}): Static Jar Test 905. Unpublished study. 

1 p. 
-33 of 38- 

Appendix A. The Risk Quotient Method and Levels of Concern 

The Risk Quotient Method is the means used by EFED to integrate the results of exposure and 

ecotoxicity data. For this method, Risk Quotients (RQs) are calculated by dividing exposure 

estimates by the acute and chronic ecotoxicity values (i.e., RQ = EXPOSURE/TOXICITY). 

These RQs are then compared to OPP's levels of concern (LOCs). These LOCs are criteria used 

by OPP to indicate potential risk to non-target organisms and the need to consider regulatory 

action. EFED has defined LOCs for acute risk, potential restricted use classification, and for 

endangered species. 

The criteria indicate that a pesticide used as directed has the potential to cause adverse effects 

on non-target organisms. LOCs currently address the following risk presumption categories: 

(1) acute - there is a potential for acute risk; regulatory action may be warranted in addition to 

restricted use classification; 

(2) acute restricted use - the potential for acute risk is high, but this may be mitigated through 

restricted use classification; 

(3) acute endangered species - the potential for acute risk to endangered species is high, 

regulatory action may be warranted; and 

(4) chronic risk - the potential for chronic risk is high, regulatory action may be warranted. 

Currently, EFED does not perform assessments for chronic risk to plants, acute or chronic 

risks to non-target insects, or chronic risk from granular/bait formulations to mammalian or 

avian species. 

The ecotoxicity test values (i.e., measurement endpoints) used in the acute and chronic RQs are 

derived from required studies. Examples of ecotoxicity values derived from short-term 

laboratory studies that assess acute effects are: (1) LC50 (fish and birds), (2) LD50 (birds and 

mammals), (3) EC50 (aquatic plants and aquatic invertebrates), and (4) EC25 (terrestrial 

plants). Examples of toxicity test effect levels derived from the results of long-term laboratory 

studies that assess chronic effects are: (1) the Lowest Observed Adverse Effect Concentration 

(LOAEC) (birds, fish, and aquatic invertebrates), and (2) the No Observed Adverse Effect 

Concentration (NOAEC) (birds, fish and aquatic invertebrates). The NOAEC is generally used 

as the ecotoxicity test value in assessing chronic effects. Risk presumptions, along with the 

corresponding RQs and LOCs are summarized in Table B1. 
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Table A1. Agency risk quotient (RQ) metrics and levels of concern (LOC) per risk class. 

Risk Class Risk Description RQ LOC 

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures 

Peak EEC/LC501 0.5 

Acute 

Restricted Use 

Potential for effects to animals from acute exposures 

Risks may be mitigated through restricted use classification 

Peak EEC/LC501 0.1 

Acute Listed 

Species 

Listed species may be potentially affected by acute 

exposures 

Peak EEC/LC501 0.05 

Chronic Potential for effects to non-listed and listed animals from 60-day EEC/NOEC (fish) 

chronic exposures 

21-day EEC/NOEC (invertebrates)

1 

Terrestrial Animals (mammals and birds) 

EEC2 Acute Potential for effects to non-listed animals from acute /LC50 (Dietary) 

exposures 

EEC/LD50 (Dose) 

0.5 

EEC2 Acute /LC50 (Dietary) 

Restricted Use 

Potential for effects to animals from acute exposures 

Risks may be mitigated through restricted use classification 

EEC/LD50 (Dose) 

0.2 

EEC 2 Acute Listed /LC50 (Dietary) 

Species 

Listed species may be potentially affected by acute 

exposures 

EEC/LD50 (Dose) 

0.1 

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures 

EEC 2/NOAEC 1 

Plants 

Non-Listed Potential for effects to non-target, non-listed plants from 

exposures 

EEC/ EC25 1 

Listed Plant Potential for effects to non-target, listed plants from EEC/ NOEC 

exposures 

EEC/ EC05

1 

1 LC50 or EC50. 2

 Based on upper bound Kenaga values. 
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Appendix B. Data Call-In Table for Propoxur 

The following Data Call-In (DCI) tables include rationales for requiring the data requested in this 

problem formulation, explanations of the utility of the data, and explanations for how the data 

might impact risk assessment. 

Guideline Number: 835.6100 (7) 

Data requirement: Environmental Chemistry Analytical Methods / independent 

laboratory validation -- soil 

Rationale for Requiring the Data 

Independently validated analytical methods for residues in soil, water, and plant material 

(environmental chemistry methods) submitted by the registrant are used to evaluate 

analyses described in submitted environmental fate and ecological effects studies. 

Submitted analytical methods are also used by various federal, state, tribal, and local 

agencies to detect and monitor residues that are suspected to be in environmental 

compartments due to outdoor uses and accidental releases. Therefore, availability of 

these analytical methods is necessary to ensure the safety of those in proximity to releases 

of propoxur residues in the environment. Independent laboratory validations for 

submitted analytical methods are necessary to confirm the levels of detection and 

quantitation reported in registrant-prepared validations. 

Practical Utility of the Data 

How will the data be used? 

In the absence of independently validated environmental chemistry methods, submitted 

environmental fate and ecological effects data may not be reviewable and entities outside 

the Agency may lack chemical-specific methods for analyses in environmental 

compartments. Independently validated environmental chemistry methods will be used 

to evaluate the submitted environmental fate and ecological effects data and will be made 

available to the public to support monitoring for propoxur residues. 

How could the data impact the Agency’s future decision making? 

Risk assessment conclusions could be altered if they are not supported by either study 

data or environmental monitoring detections that are based on independently validated 

environmental chemistry methods. Furthermore, while not directly related to Agency 

decision making, independently validated environmental chemistry methods are 

necessary to ensure the safety of those in proximity to releases of propoxur residues in 

the environment. 
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Guideline Number: 850.2200 

Study Title: Avian Dietary Toxicity Test (Bobwhite and Mallard) 

Rationale for Requiring the Data 

Studies previously submitted by the registrant in support of this guideline have either 

been classified as invalid or supplemental. The supplemental studies do not satisfy the 

guideline and are not upgradeable based on flaws in their experimental design. 

These data are designed to provide information on the dietary toxicity of pesticides to 

birds. Birds are exposed to different levels of pesticides in their diet for 5 days of feeding 

and a dose response curve is determined. The current use of propoxur that is being 

assessed for risk is a 2% granular bait application. The information contained in this type 

of study is essential to determine the toxicity of propoxur to birds that may ingest 

propoxur granules. As shown by the incident reports, this type of exposure has already 

resulted in bird mortality. 

Practical Utility of the Data 

How will the data be used? 

As part of registration review, the Agency plans to conduct a new ecological risk 

assessment including an endangered species assessment for propoxur. In the absence of 

this data, no dietary RQ’s can be calculated to assess the risk to birds, and the Agency 

would have to assume that propoxur “may affect” birds, and those taxa for which birds 

are a surrogate, directly (and endangered species from other taxa indirectly).

How could the data change the Agency’s decision or impact the Agency’s future 

decision-making? 

Open literature studies may provide additional information, but they cannot be used to 

fulfill guideline requirements. The data are required according to the 40 CFR guidelines 

for an upland and waterfowl species. Open literature studies classify the chemical as 

highly toxic to very highly toxic to birds, whereas registrant submitted studies classify 

propoxur as slightly to practically non-toxic. Given the flaws in the experimental design 

of the registrant submitted studies, the data from new studies will provide a more 

accurate assessment of the toxicity of propoxur to avian species and allow the Agency to 

refine the risk to avian species and those species for which birds are a surrogate. In 

addition, the lack of these data will limit the flexibility the Agency and registrants have in 

coming into compliance with the Endangered Species Act, and could result in use 

restrictions for propoxur, which may otherwise be avoided or which are unnecessarily 

severe. 
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Guideline Number: 850.2300 

Study Title: Avian Reproduction (Bobwhite and Mallard) 

Rationale for Requiring the Data 

Since the RED was signed, the Agency has worked to finalize its update to the data 

requirements in 40 CFR part 158, which were promulgated in October 2007. Now two 

avian reproduction studies, one with a waterfowl and one with an upland game bird, are 

required to support all terrestrial use patterns. 

Propoxur is applied in granular form around residential, commercial, and industrial 

structures. Both listed and non-listed birds may come into contact with this granular 

formulation. This data is necessary to provide information on the potential reproductive 

effects to both listed and non-listed species. 

The registrant previously provided two studies on avian reproduction toxicity, which 

were both classified as supplemental. However, the Bobwhite quail study did not 

establish a NOEC, which is important to assessing chronic risk to avian species. The 

mallard duck study did not satisfy the guideline requirement although it did suggest 

reproductive toxicity of propoxur to mallard ducks. New acceptable Bobwhite quail and 

mallard duck studies are needed to refine the reproductive risk to avian species due to 

environmental exposure to propoxur according to the 40 CFR part 158 requirements for 

all outdoor uses. 

Practical Utility of the Data 

How will the data be used? 

These data are necessary to characterize the potential risks to birds, terrestrial-phase 

amphibians and reptiles associated with the use of propoxur. These data will be used in 

the national-level risk assessment to estimate the scope of sub-lethal effects and potential 

chronic risks associated with the use of propoxur. 

How could the data impact the Agency’s future decision-making? 

The data from the bobwhite and mallard reproductive toxicity studies will clarify the 

reproductive toxicity of propoxur, which is already suggested by one of the previously 

submitted studies, to birds, terrestrial-phase amphibians and reptiles. This information 

could further refine the risk assessment to these wildlife taxa that are both listed and nonlisted. The lack of these data will limit the flexibility the Agency and registrants have in 

coming into compliance with the Endangered Species Act, and could result in use 

restrictions for propoxur which may otherwise be avoided, or which are unnecessarily 

severe. 
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Guideline Number: 850.4225, 850.4250 

Study Title: Terrestrial Plant Toxicity: Tier II Seedling Emergence and Vegetative 

Vigor 

Rationale for Requiring the Data 

Propoxur toxicity data for non-target terrestrial and aquatic plants are not available. 

Based on the 40 CFR Part 158 data requirements, Tier I level seedling emergence and 

vegetative vigor non-target terrestrial plant data are required for all outdoor uses. Minor 

incidents have been reported that suggests propoxur has phytotoxic properties. Given 

this evidence, Tier II seedling emergence and vegetative vigor studies are being 

requested. 

Practical Utility of the Data 

How will the data be used? 

Data from Tier II plant toxicity studies will be used to estimate potential risks to 

terrestrial plants associated with the use of propoxur. The data will reduce uncertainties 

associated with the current risk assessment for terrestrial plants and will improve the 

Agency’s understanding of the potential effects of propoxur on terrestrial and aquatic 

plants. In the absence of this data, risk for terrestrial plants will be presumed. 

How could the data impact the Agency’s future decision-making?

Because terrestrial plants form the basis of the food chain for terrestrial habitats and 

significantly contribute to overall habitat quality, a solid understanding of the potential 

risks to terrestrial plants is essential for sound environmental risk management decisionmaking. Without terrestrial plant data for propoxur, the Agency cannot determine if the 

current application rates of propoxur may result in direct adverse effects to terrestrial 

plants and/or indirect effects resulting from reduction in the prey base and/or loss of 

habitat/cover. Previous applications of propoxur have already resulted in minor incidents 

of plant damage as reported in the aggregate minor incident reports (section 4.4), which 

suggests the possibility of phytotoxic effects related to propoxur exposure. If future 

endangered species risk assessments are performed without these data, the Agency would 

have to assume that propoxur “may affect” terrestrial plants directly (and listed species 

from other taxa indirectly via reduction in prey base and/or habitat), and use of propoxur 

may need to be restricted in areas where listed species could be exposed and/or critical 

habitat is present. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act and could 

result in use restrictions for propoxur which are unnecessarily severe.