UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

PC Code: 016331 

DP Barcode: 410075 

December 4, 2014 

MEMORANDUM 

SUBJECT: Environmental Fate and Ecological Risk Assessment for the Section 3 New 

Chemical Registration of the Pyrethroid Insecticide Momfluorothrin 

TO: 

FROM: 

Through: 

Julie Chao, Risk Manager Reviewer 

Kable Davis, Product Manager Team 25 

Insecticide/Rodenticide Branch 

Registration Division (7505P) A# _ .,Aj JZ _ '{- Z OJ'{ 

Nathan Miller, Biologist 1Mfii:: Jl(ft. 

Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist W{J, ( l=cr tAS) [1-\.}- l '--\ 

Environmental Risk Branch VI · 

Environmental Fate and Effects Division (7507P) 

Mark Corbin, Branch Chief u \L-'·~-~w r {--;;t~~ f ( 1..- q..-!cj 

Monica Wait, Risk Assessment Process Leader <./' Ww 

William P. Eckel, Ph.D., Senior Scie0ce Adv 

Amy Blankinship, Senior Biologist ~ 

Environmental Risk Branch VI "'\.vv _ • • _ J & ..1. u , .. ~ VV~\o' 12..---.-Jt Environmental Fate and Effects Division (7507P) 

The Environmental Fate and Effects Division (EFED) has completed the screening level 

assessment of the environmental fate and ecological risks ofthe proposed new chemical 

momfluorothrin (PC Code 016331 ). This assessment is for a national registration of aerosol 

spray can products intended for residential spot and crack and crevice treatments, or wasp and 

hornet nest treatments. The following are considered target pests: flying insects (e.g., flies, 

mosquitoes, and gnats), stinging insects (e.g., hornets, wasps, yellow jackets, and mud daubers), 

spiders, and crawling insects (e.g., roaches, ants, centipedes, scorpions, and sowbugs). 

While ecotoxicity data gaps exisit, the environmental fate and ecotoxicity databases are 

sufficient for assessing the risk associated with the proposed aerosol spray can uses. Expansion 
-Page 2 of 62-

of the proposed momfluorothrin use pattern to include broadcast applications (e.g., agricultural 

or mosquito adulticide uses) will require additional environmental fate and ecological effects 

data to support those uses.

Summary of Risk Conclusions

The results of this screening-level assessment on the proposed momfluorothrin uses indicate low 

potential risk for non-target aquatic animals and terrestrial invertebrates based on risk level of 

concern exceedances. Aquatic risk predictions for fish and aquatic invertebrates are low under 

EFED’s standard exposure scenario due to the nature of the proposed uses and aerosol 

formulations. While much smaller water bodies in close proximity to treated areas may have 

increased vulnerability due to the highly toxic nature of the product, the requisite exposure to 

reach risk levels of concern is unlikely considering that direct application to water is prohibited 

and runoff is mitigated by the labels’ restriction regarding applications near surface water (i.e.,

the 25 foot buffer). Results of this screening-level ecological risk assessment indicate that the 

proposed uses of momfluorothrin are unlikely to result in direct adverse effects to listed species 

of any taxon. Since direct effects are not predicted, indirect effects are not expected to result 

from the proposed uses of momfluorothrin. 

For the drinking water assessment, EFED believes based on the use pattern (i.e. ready-to-use 

spray cans), while some outdoor exposure is possible, it is unlikely the use will yield aquatic 

exposures that will impact drinking water. For that reason, no quantitative drinking water 

assessment (DWA) has been conducted for these products and this use pattern. EFED believes 

that this evaluation is consistent with previous assessments for this particular outdoor use pattern 

for other pesticides. Should the registrant amend or add to this use pattern, EFED will reconsider 

the need for a DWA depending on the nature of the changes (DP Barcode: 410074; 02/12/2014).

Uncertainties

Ecotoxicological data gaps exist for avian reproduction toxicity, avian acute oral toxicity 

(passerine species), benthic invertebrate chronic toxicity, estuarine/marine acute and chronic 

animal toxicity, aquatic nonvascular plant toxicity, and terrestrial plant toxicity. While 

ecotoxicity data gaps exisit, available ecological effects data are sufficient for assessing the risk 

associated with the proposed aerosol spray can use because the predicted exposures are expected 

to be spatially restricted to small areas. 

Recommended Label Amendments

Based on the available toxicity data, momfluorothrin product labels should state that 

momfluorothrin is toxic to fish, aquatic invertebrates and terrestrial invertebrates where 

applicable (e.g., labels for outdoor use); however, some of the proposed labels do not include this 

language and each of the proposed momfluorothrin labels has a unique Environmental Hazards 

section. Each momfluorothrin product label registered for outdoor use should share a consistent 

environmental hazard statement. The following generic environmental hazard statements are

suggested for placement on each momfluorothrin product label being considered for outdoor use:
-Page 3 of 62-

“To protect the environment, do not allow pesticide to enter or run off into storm drains, 

drainage ditches, gutters or surface waters. Applying this product in calm weather when 

rain is not predicted for the next 24 hours will help to ensure that wind or rain does not 

blow or wash pesticide off the treatment area.”

“This pesticide is toxic to fish and aquatic invertebrates.”

“Drift and runoff may be hazardous to aquatic organisms in water adjacent to treated 

areas”

“This product is highly toxic to bees exposed to direct treatment on blooming crops or 

weeds. Do not apply this product or allow it to drift to blooming crops or weeds while 

bees are actively visiting the area.”

The following Environmental Hazard statements appear on the proposed product labels:

10308-GA

 This product is toxic to fish, and to bees exposed to direct treatment. Do not apply this 

product while bees are actively visiting the treatment area. Do not apply directly to water.

MGK-29811 (For indoor residential use only)

 This pesticide is extremely toxic to fish and aquatic invertebrates. Do not apply directly 

to or near water. 

MGK-29831

 This pesticide is toxic to environmental organisms, including fish and invertebrates. Do 

not apply directly to or near water. Drift and run-off may be hazardous to fish in water 

adjacent to treated areas.

MGK-29871

 This product is highly toxic to fish and other aquatic invertebrates. Do not apply directly 

to water. Drift and runoff may be hazardous to aquatic organisms in water adjacent to 

treated areas.

MGK-29872

 This pesticide is extremely toxic to aquatic organisms, including fish and aquatic 

invertebrates. Do not apply directly to water. Drift and runoff may be hazardous to 

aquatic organisms in water adjacent to treated areas. Applying this product in calm 

weather when rain is not predicted for the next 24 hours will help to ensure that wind or 

rain does no blow or wash pesticide off the treatment area. This product is highly toxic to 

bees exposed to direct treatment on blooming crops or weeds. Do not apply this product 

or allow it to drift to blooming crops or weeds while bees are actively visiting the area.

The current Sumitomo S-1563 Flying and Crawling Insect Killer Spray (EPA Reg no. 10308-
-Page 4 of 62-

GA) label prohibits use within 25 feet of saltwater. This use restriction should be modified to 

include freshwater areas because of its high toxicity to aquatic organisms and to be consistent 

with other pyrethroid product labels. 

The MGK-29811 label states that it is intended for indoor residential use only. However, site use 

claims include outdoor areas. These discrepancies should be resolved, but will not affect the 

ecological risk assessment conclusions since similar MGK products registered for outdoor use 

were considered. 

Label language should be consistent with the recommendations of EPA’s February 2013 

guidance titled: “Environmental Hazard and General Labeling for Pyrethroid and Synergized 

Pyrethrins Non-Agricultural Outdoor Products,” available at:

http://www.epa.gov/oppsrrd1/reevaluation/environmental-hazard-statment.html

Response to Comments

During the 30-day public comment period on the Federal Register Notice announcing the receipt 

of the momfluorothrin registration application (78 FR 64937), the Agency received two public 

comments regarding the evaluation of momfluorothrin for registration in the United States. One 

comment was from the California Stormwater Quality Association (CASQA), and the second 

was from the San Francisco Bay Regional Water Quality Control Board (SFB RWQCB). Both 

comments are available in the docket at www.regulations.gov, EPA-HQ-OPP-2013-0478, 

comments -0002 and -0003. Parts of both comments were similar in requesting that EPA conduct 

a full evaluation of the potential for momfluorothrin products to cause adverse impacts in the 

water column and sediment in urban waters. Excerpts from the submitted comments and EPA’s 

responses are provided below.

CASQA and SFB RWQCB:

We request that U.S. EPA carefully evaluate all momfluorothrin product registration 

applications. Specifically, we request a full evaluation of the potential for momfluorothrin 

products to cause adverse impacts in the water column and sediment in urban waters. We 

request that U.S. EPA consider all urban application locations and evaluate potential 

pathways to receiving waters under conditions consistent with label instructions. The 

evaluation should include any stable degradates and the time required for the active 

ingredient and degradates to become non-toxic. If momfluorothrin use consistent with label 

instructions can result in toxicity in receiving waters, further restrictions on use (such as 

modified label instructions or limitations on the types of retail products sold) must be 

evaluated. We encourage U.S. EPA to pay special attention to application types—like control 

of insects around buildings and preconstruction termiticide applications—that are being 

addressed in U.S. EPA’s pyrethroids registration reviews, such as the bifenthrin review. We 

suggest that U.S. EPA’s workplan for reviewing this registration application and the data 

requirements for momfluorothrin registration be comparable to the workplans and data 

requirements for the pyrethroids undergoing registration review.
-Page 5 of 62-

EPA Response:

EPA appreciates the comments provided by the California Stormwater Quality Association and 

the San Francisco Bay Regional Water Quality Control Board regarding the proposed 

registration of momfluorothrin.

EPA recognizes that pyrethroid insecticides have created issues with sediment toxicity, 

especially in urban areas, as a results of runoff from use sites and discharge from sewage 

treatment plants. Data for Chironomus dilutus do indicate that momfluorothrin is toxic to 

benthic invertebrates (49-day NOAEC for growth and reproduction is less than 13 micrograms 

per kilogram sediment, or 1.8 μg/L pore water). 

The proposed uses of momfluorothrin, which include only indoor and outdoor spray cans to kill 

flying insects, are unlikely to result in sufficient usage to contribute to sediment burdens of 

pyrethroids. None of the proposed uses is believed to result in a down-the-drain type exposure, 

thus POTW effluent and biosolids issues are not believed to be of concern. 

In the event that momfluorothrin is transported to a waterway, its exceptionally low partition 

coefficients (Koc = 1033 to 4344 L/kg o.c.) and log Kow (2.88) indicate that it is much less likely 

to partition to sediment than other pyrethroids currently on the market. Should momfluorothrin 

be transported to, and persist in sediment (which is considered unlikely), its effects would likely 

be additive with those of other pyrethroids.

Momfluorothrin also degrades quickly, in comparison to other pyrethroids, by a number of 

processes, including alkaline hydrolysis, aqueous photolysis, and aerobic metabolism in soil and 

water. Half-lives are on the order of a few days. Thus it is not persistent, like other pyrethroids, 

and is again less likely to contribute to chronic sediment toxicity. These fate properties also 

suggest that momfluorothrin would be degraded in a POTW. 

SFB RWQCB

Consider cumulative impacts—Evaluate pesticide mixtures occurring in surface waters, 

such as mixtures with other pyrethroids, which commonly occur in surface waters. Mixtures 

could be a significant factor contributing to any potential toxic effects of momfluorothrin. 

EPA Response:

A prospective (i.e., predictive) ecological risk assessment of pesticide mixtures would require a 

substantial amount of information regarding the temporal and spatial extent of pesticide usage 

within a watershed, which is currently lacking. This information is needed to accurately predict 

(or screen) pesticide concentrations in a waterbody because different pesticides will be applied at 

different times and locations within any given watershed. In addition, a watershed-based model 

would also need to be developed and reviewed for this particular application in order to capture 

the temporal and spatial dynamics of multiple pesticide uses and applications. Although a 

prospective cumulative ecological risk assessment methodology is subject to these and other 

challenges related to exposure and effects assessment, the EPA believes that available 
-Page 6 of 62-

monitoring data for pyrethroids do offer some potential to evaluate cumulative ecological risk in 

a retrospective manner. The Agency will consider monitoring data of pyrethroid mixtures, such 

as concentrations in sediments, in the context of their potential to provide insight into ecological 

risks of pyrethroid mixtures to the extent that simplified assumptions regarding their combined 

toxicity (additivity) are scientifically supported. 

SFB RWQCB

Study effects on benthic biota—Conduct sediment toxicity studies (with spiked sediment, 

rather than by adding momfluorothrin to the overlying water). Momfluorothrin is expected to 

deposit and persist in aquatic sediment. 

EPA Response:

As discussed above, momfluorothrin degrades quickly in comparison to other pyrethroids by a 

number of processes, including alkaline hydrolysis, aqueous photolysis, and aerobic metabolism 

in soil and water. Half-lives are on the order of a few days. Thus it is not persistent, like other 

pyrethroids, and is less likely to contribute to chronic sediment toxicity. Available chronic 

sediment toxicity testing with midge was conducted using spiked sediment.
-Page 7 of 62-

Environmental Fate and Ecological Risk Assessment 

for the Registration of Momfluorothrin 

Momfluorothrin

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-(1RS,3RS,1RS,3SR)-3-(2-

cyanoprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate

CAS Registry Number: 609346-29-4

PC Code: 016331

Prepared by:

Nathan Miller, Biologist

Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington DC 20460

Reviewed by:

Amy Blankinship, Senior Biologist, ERB VI

William P. Eckel, Ph.D, Senior Science Advisor, ERB VI

Mark Corbin, Branch Chief, ERB VI

December 4, 2014
-Page 8 of 62-

Table of Contents

1. Executive Summary .............................................................................................................. 9

1.1. Nature of Chemical Stressor....................................................................................................................9

1.2. Potential Risks to Non-target Organisms...............................................................................................9

1.3. Conclusions - Exposure Characterization ............................................................................................10

1.4. Conclusions - Effects Characterization.................................................................................................10

2. Problem Formulation ......................................................................................................... 12

2.1. Nature of Regulatory Action..................................................................................................................12

2.2. Stressor Source and Distribution ..........................................................................................................12

2.2.1. Nature of Chemical Stressor..............................................................................................................12

2.2.2. Overview of Pesticide Usage.............................................................................................................13

2.3. Receptors.................................................................................................................................................13

2.3.1. Aquatic and Terrestrial Effects..........................................................................................................13

2.3.2. Ecosystems Potentially at Risk..........................................................................................................14

2.4. Assessment Endpoints............................................................................................................................14

2.5. Conceptual Model ...................................................................................................................................14

2.5.1. Risk Hypotheses................................................................................................................................14

2.5.2. Conceptual Diagram..........................................................................................................................15

2.6. Analysis Plan ...........................................................................................................................................18

2.6.1. Residues of Concern..........................................................................................................................18

2.6.2. Preliminary Identification of Data Gaps and Uncertainties...............................................................18

2.6.3. Evaluation of Multiple Active Ingredients and Mixtures..................................................................18

2.6.4. Measures of Exposure .......................................................................................................................18

2.6.5. Measures of Effect.............................................................................................................................19

2.6.6. Integration of Exposure and Effects..................................................................................................21

3. Analysis............................................................................................................................. 22

3.1. Use Characterization..............................................................................................................................22

3.2. Exposure Characterization....................................................................................................................23

3.2.1. Environmental Fate and Transport Characterization .........................................................................23

3.2.2. Measures of Aquatic Exposure..........................................................................................................27

3.2.3. Measures of Terrestrial Exposure......................................................................................................27

3.3. Ecological Effects Characterization......................................................................................................28

3.3.1. Aquatic Toxicity Assessment ............................................................................................................28

3.3.2 Terrestrial Effects Characterization...................................................................................................31

4. Risk Characterization......................................................................................................... 34

4.1. Risk Estimation.......................................................................................................................................34

4.2. Risk Description......................................................................................................................................34

4.2.1. Risk to Aquatic Organisms................................................................................................................34

4.2.2. Risk to Terrestrial Organisms............................................................................................................37

4.3. Uncertainties and Data Gaps.................................................................................................................40

4.3.2. Effects Uncertainties .........................................................................................................................40

5. Federally Threatened and Endangered (Listed) Species Concerns............................... 41

5.1. Action Area .............................................................................................................................................41

5.2. Taxonomic Groups Potentially at Risk.................................................................................................42

5.2.1. Probit Dose-Response Analysis ......................................................................................................43

6. References............................................................................................................................ 44

6.1. Submitted Environmental Fate and Transport Studies.....................................................................45

6.2. Submitted Ecotoxicity Studies..............................................................................................................47

Appendix A. Sumary of Environmental Fate Data for Momfluorothrin .............................. 51

Appendix B. Sumary of Ecological Effects Data for Momfluorothrin .................................. 54

Appendix C. Model Outputs...................................................................................................... 59
-Page 9 of 62-

1. Executive Summary

1.1. Nature of Chemical Stressor

Sumitomo Chemical Company is seeking registration for the new chemical insecticide 

Momfluorothrin (2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-(1RS,3RS,1RS,3SR)-3-(2-

cyanoprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate); CAS#: 609346-29-4; PC code: 

016331). Momfluorothrin is new synthetic pyrethroid insecticide that is proposed for use to 

control a wide range of insects and other arthropods.

Momfluorothrin, like other pyrethroids, is considered an axonic poison that prevents sodium 

channels in an organism’s neuronal membranes from closing, resulting in paralysis. 

Momfluorothrin consists of 8 isomers, but is composed primarily of the RTZ (approximately 

90%) and RTE isomers (approximately 10%). The minimum R isomer ratio is 0.98, the 

minimum Z isomer ratio is 0.90, and the minimum trans isomer ratio is 0.99 (Habig, 2012).

This assessment is for a national registration request for non-agricultural, non-food use control of 

the following target pests: flying insects (flies, mosquitoes, gnats), stinging insects (hornets, 

wasps, yellow jackets, mud daubers), spiders, and crawling insects (roaches, ants, centipedes, 

sowbugs, and scorpions). The proposed uses of momfluorothrin include indoor uses and limited 

outdoor uses. Indoor uses are proposed against several types of flying and crawling household 

pests. Proposed outdoor uses include several types of stinging insects, flies, and crawling pests.

Application method for both indoor and outdoor uses is only through the use of a hand-held 

aerosol can.

According to a risk assessment prepared by Cliff Habig of Compliance Services International 

(Habig, 2012), product spray release rates for flying insect killers (FIKs) are generally 

approximately 1 g product/sec, while the product release rate for crawling insect killers (CIKs) 

are typically approximately 3 g product/second. The second major type of product containing 

momfluorothrin is the wasp and hornet killer (W+H), which contains momfluorothrin at a 

concentration of 0.05% w/w. This is also marketed in spray cans containing approximately 500 g 

end-use product. The release rate for W+H products is higher than those for FIKs or CIKs. W+H 

products generally release a jet spray of product at 20 g /second; this spray typically travels about 

20 feet to its target, reducing the possibility of the applicator being stung. FIKs, CIKs, and W+ H 

formulations will also contain either a second active ingredient, such as phenothrin or 

cypermethrin; or a synergist, such as piperonyl butoxide (PBO).

Major transformation products resulting from the environmental degradation of momfluorothrin

are MFOA-D and TFPA, Z-CMCA and omega c-CONH2-d-t-CRA, which degrades further to 

CO2. No momfluorothrin transformation products are considered in this risk assessment because 

they are not as toxic as the parent compound.

1.2. Potential Risks to Non-target Organisms

Results of this screening-level ecological risk assessment indicate that the proposed uses of 
-Page 10 of 62-

momfluorothrin are unlikely to result in direct adverse effects to listed species of any taxon

(Table 1.1), and a "no effect" determination is made. Since direct effects are not predicted, 

indirect effects are not expected to result from the proposed uses of momfluorothrin. 

Table 1.1. Potential Effects to Federally Listed Taxa Associated with Direct or Indirect 

Effects from the Proposed New Uses of Momfluorothrin.

Listed Taxon Direct Effects Indirect Effects

Terrestrial and semi-aquatic plants - monocots No No

Terrestrial and semi-aquatic plants - dicots No No

Birds No No

Terrestrial-phase amphibians and reptiles No No

Mammals No No

Terrestrial invertebrates No No

Aquatic nonvascular plants No No

Aquatic vascular plants No No

Freshwater fish No No

Aquatic-phase amphibians No No

Freshwater crustaceans No No

Mollusks No No

Marine/estuarine fish No No

Marine/estuarine invertebrates No No

1.3. Conclusions - Exposure Characterization 

Momfluorothrin has low water solubility (approximately 0.9 mg/L at 20°C), low vapor pressure

(approximately 1.04 x 10-8 Torr at 25°C), and a moderate log Kow (approximately 2.88). 

Momfluorothrin is non-persistent in the environment. It is stable to hydrolysis at pH 4 and 7, but 

undergoes hydrolysis at pH 9, with half-lives of approximately 12 days at 20°C and 7 days at 

25°C. Momfluorothrin is susceptible to photolysis in water, with a half-life of approximately 13 

days under continuous illumination, which is equivalent to a half-life of approximately 32 U.S. 

solar days (at 40°N latitude). Momfluorothrin undergoes rapid microbial degradation under 

aerobic conditions in soil, with half-lives less than 5 days, and in water-sediment systems, with 

half-lives of less than 3 days. Momfluorothrin binds tightly to soil, with Kocs ranging from 1033 

to 4344 for four different soils and one sediment.

Measures of exposure for pesticide ecological and environmental fate risk assessments are 

typically based on aquatic and terrestrial models that estimate environmental concentrations of 

pesticides using labeled application rates and methods for broadcast-applied pesticides. 

However, since the proposed momfluorothrin end-use products are formulated as aerosol spray 

cans for localized uses and not for large scale broadcast applications and since the 

momfluorothrin end-use products do not have a maximum label rate, the exposure assessment for 

momfluorothrin is qualitative in nature.

1.4. Conclusions - Effects Characterization 

For aerosol spray applications of momfluorothrin, no acute or chronic risks of concern are 

identified for aquatic animals on the basis of limited exposure. Risk to aquatic vascular and 
-Page 11 of 62-

nonvascular plants is not expected.

Acute and chronic risk to avian or mammalian species is not expected for aerosol spray 

applications of momfluorothrin. Risk to non-target terrestrial invertebrates is considered low on 

the basis of limited exposure.

While there is uncertain risk to terrestrial plants because of observed toxicity at one of the limit

doses tested, risk exceeding nontarget terrestrial plant levels of concern is not expected for the 

proposed aerosol spray can use pattern. 
-Page 12 of 62-

2. Problem Formulation

The purpose of problem formulation is to provide the foundation for the environmental fate and 

ecological risk assessment for the registration of the new chemical momfluorothrin, (2,3,5,6-

tetrafluoro-4-(methoxymethyl)benzyl (EZ)-(1RS,3RS,1RS,3SR)-3-(2-cyanoprop-1-enyl)-2,2-

dimethylcyclopropanecarboxylate); CAS#: 609346-29-4; PC code: 016331). The problem 

formulation sets the objectives for the risk assessment, establishes a risk hypothesis and 

conceptual model depicting potential risk, and provides a plan for analyzing the data and 

characterizing the risk associated with the proposed use of momfluorothrin (USEPA, 1998). 

2.1. Nature of Regulatory Action

The U.S. Environmental Protection Agency (EPA or the Agency) is required under the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) to ensure that the newly proposed use of

momfluorothrin as an insecticide does not have the potential to cause unreasonable adverse 

effects to the environment. In addition to non-target animals and plants, potential effects to 

listed species (i.e., species on the Federal list of endangered and threatened wildlife and plants)

and their designated critical habitat are also considered under the Endangered Species Act (ESA) 

in order to ensure that the registration of momfluorothrin is not likely to jeopardize the continued 

existence of listed species or adversely modify their critical habitat. In order to meet the 

requirements of FIFRA and the ESA, this assessment follows EPA guidance on conducting 

ecological risk assessments (USEPA, 1998) and Office of Pesticide Program’s Overview 

Document, which contains guidance for assessing pesticide risks to non-target and listed 

organisms (USEPA, 2004).

The end result of the EPA pesticide registration process (i.e., the FIFRA regulatory action) is an 

approved (or disapproved) product label. The label is a legal document that stipulates how and 

where a given pesticide may be used. Product labels (also known as end-use labels) describe the 

formulation type (e.g., liquid or granular), acceptable methods of application, approved use sites, 

and any restrictions on how applications may be conducted. Therefore, the use, or potential use, 

described by the pesticide’s labels is considered “the action” being assessed. This assessment 

was prepared to support evaluation of the proposed new chemical registration of 

momfluorothrin.

2.2. Stressor Source and Distribution

2.2.1. Nature of Chemical Stressor

According to the technical registrant, Sumitomo Chemical Company, momfluorothrin is a 

knockdown pyrethroid insecticide (Habig, 2012). The pyrethroids (including momfluorothrin) 

share a similar mode of action (MOA), and are considered axonic poisons that affect both the 

peripheral and central nervous system. It is now well established that severe neurological 

symptoms of poisoning with pyrethroids in mammals and insects are the result of modification of 

sodium (Na+) channel activity (cellular pores through which sodium ions are permitted to enter 

the axon to cause excitation) (Matsumura 1985). 
-Page 13 of 62-

Five end-use product formulations containing momfluorothrin were submitted with the new 

chemical package. All proposed formulations are aerosol sprays intended for use in and around 

houses and buildings where the target pests may be found. The proposed uses for 

momfluorothrin products fall under the indoor and residential/utility outdoor general use pattern 

categories. All of the proposed formulations containing momfluorothrin have concentrations of 

momfluorothrin in the range of 0.025% to 0.1% w/w. Product spray release rates for flying insect 

killers (FIKs) are generally approximately 1g product/sec, while the product release rate for 

crawling insect killers (CIKs) is typically approximately 3g product/second. The product release 

rate for the wasp and hornet killer (W+H) product is 20 g product/second.

2.2.2. Overview of Pesticide Usage

Usage data are not available for momfluorothrin because it is a new active ingredient proposed 

for use in the United States. Momfluorothrin is currently proposed exclusively for formulation 

into hand-held aerosol spray cans for residential/utility use by consumers.

2.3. Receptors

2.3.1. Aquatic and Terrestrial Effects

In ecological risk assessment, a receptor is a biological entity that is exposed to a stressor 

(USEPA, 1998). Consistent with the process described in the Overview Document (USEPA, 

2004), this risk assessment uses a surrogate species approach in its evaluation of 

momfluorothrin. Toxicity data generated using surrogate test species, which are intended to be 

representative of broad taxonomic groups, are used to infer potential effects on a variety of 

species (receptors) included under these broader taxonomic groupings. Table 2.1 provides the 

general taxonomic groups and surrogate species tested to evaluate potential ecological effects of 

momfluorothrin to broad classes of non-target organisms. Within each of these taxonomic 

groups, a measure of effect is selected from among the available test data. 

Table 2.1. Taxonomic Groups and Test Species Evaluated for Assessing Potential 

Ecological Effects of Momfluorothrin.

Taxonomic Group Typical Species

Birds1 Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Mammals Norway rat (Ratus norvegicus)

Invertebrates Honey bee (Apis mellifera L.)

Freshwater fish2 Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Fathead minnow (Pimephales promelas)

Freshwater invertebrates Water flea (Daphnia magna)

Midge (Chironomus riparius)

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus)

Estuarine/marine invertebrates Mysid (Americamysis bahia)

Eastern oyster (Crassostrea virginica)

Terrestrial plants3 Monocots – Crop species, such as corn (Zea mays)

Dicots – Crop Species, such as soybean (Glycine max)
-Page 14 of 62-

Table 2.1. Taxonomic Groups and Test Species Evaluated for Assessing Potential 

Ecological Effects of Momfluorothrin.

Taxonomic Group Typical Species

Aquatic plants and algae4 Duckweed (Lemna gibba) 

Freshwater Algae (Pseudokirchneriella subcapitata)

1 Birds represent surrogates for terrestrial-phase amphibians and reptiles.

2 Freshwater fish may be surrogates for aquatic-phase amphibians.

3 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of which one is soybeans.

4 Four species of non-vascular algae including a freshwater green algae, a cyanobacterium, a marine diatom, and a freshwater diatom. 

2.3.2. Ecosystems Potentially at Risk 

The ecosystems potentially 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, terrestrial ecosystems potentially at risk could include 

the treated site and immediately adjacent areas that may receive drift or runoff. For the proposed 

uses for momfluorothrin, areas adjacent to the treated site could include gardens, residential 

landscaping, and property edges. Aquatic ecosystems potentially at risk include water bodies 

adjacent to or downstream from use sites, and might include impounded bodies such as ponds, 

lakes and reservoirs, or flowing waterways such as streams or rivers including all adjacent offchannel habitats that are permanently or intermittently connected to flowing waters. For uses in 

coastal areas, aquatic habitat also includes marine ecosystems, including estuaries, embayments, 

and near-shore environments such as tidal marshes.

2.4. 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 momfluorothrin, ecological entities of potential concern include the 

following: birds, amphibians, reptiles, mammals, freshwater fish and invertebrates, 

estuarine/marine fish and invertebrates, terrestrial plants, non-target terrestrial invertebrates, and 

aquatic vascular and non-vascular plants. The attributes for each of these entities may include 

growth, survival, and reproduction (Table 2.2 in Section 2.6.4).

2.5. 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 mechanism, and a 

feasible route of exposure.

The conceptual model is intended to provide a written description and visual representation of 

anticipated relationships between momfluorothrin, potential routes of exposure, and the predicted 

effects for the assessment endpoints. The conceptual model consists of two major components: 

risk hypotheses and a conceptual diagram (USEPA, 1998).

2.5.1. Risk Hypotheses
-Page 15 of 62-

For momfluorothrin, the following generic ecological risk hypothesis is being employed for this 

screening-level risk assessment:

Momfluorothrin, when used in accordance with registered labels, has the potential to

move off-site via spray drift leading to exposure of nontarget plants and animals. Based 

on information on the environmental fate, mode of action, direct toxicity and potential 

indirect effects, EFED considers that the proposed uses of momfluorothrin have the 

potential to cause reduced survival, growth, and reproduction to non-target terrestrial 

and aquatic animals and plants.

2.5.2. Conceptual Diagram

The conceptual models for aquatic and terrestrial exposures are shown in Figures 1 and 2, 

respectively. For the currently registered uses, momfluorothrin is released into the air as 

suspended particles. For these uses, the active ingredient is initially present in the atmosphere in 

a volatile form but is expected to dissipate rapidly through a combination of degradation and 

dilution by the large volume of air into which it is released. Aquatic and terrestrial exposure 

occurs only after momfluorothrin has been deposited on land or water surfaces. In the 

conceptual models, dashed lines denote exposure routes not assessed due to the low likelihood of 

exposure. 
-Page 16 of 62-

Figure 1. Conceptual model for momfluorothrin effects on aquatic organisms.

Stressor

Source

Receptors

Attribute

Change

Momfluorothrin applied as aerosol sprays

Drift

Aquatic animals

Invertebrates 

Vertebrates

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae and 

 vascular plants

Reduction in prey

Modification of PCEs 

 related to prey 

availability

Habitat integrity

Reduction in primary 

productivity

Reduced cover

Community change

Modification of PCEs related 

to Habitat 

 habitat

Surface water/

Sediment

Runoff 

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Atmospheric 

transport

Wet/dry deposition

Soil

Leaching to

Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves

Riparian plants

terrestrial exposure
-Page 17 of 62-

Figure 2. Conceptual model for momfluorothrin effects on terrestrial organisms.

Stressor

Source

Attribute

Change

Momfluorothrin applied as aerosol sprays

Direct

application Drift

Terrestrial 

vertebrates

Terrestrial 

Inverts

Individual organisms

Reduced survival

Reduced growth

Reduced 

reproduction

Food chain

Reduction in prey and 

food

Modification of PCEs 

 related to prey 

availability

Habitat integrity

Reduction in primary 

productivity

Reduced cover

Community change

Modification of PCEs related

 to habitat

Terrestrial plants

grasses/forbs, fruit, 

seeds (trees, shrubs)

Runoff

Terrestrial 

vertebrates 

Exposure 

Media 

& Receptors

Soil

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport

Root uptake/contact

Wet/dry deposition

Ingestion

Leaching to

Groundwater

Irrigation 

water
-Page 18 of 62-

2.6. Analysis Plan

2.6.1. Residues of Concern

No momfluorothrin transformation products are identified as residues of concern; the exposure 

assessment considers only the momfluorothrin parent compound.

2.6.2. Preliminary Identification of Data Gaps and Uncertainties

The submitted environmental fate and ecotoxicity data are sufficient to assess the risk associated 

with the aerosol spray can use; however, any future submissions for new uses of momfluorothrin 

will prompt a re-evaluation of the data needed for risk assessment. Submitted momfluorothrin 

environmental fate data are summarized in Appendix A.

2.6.3. Evaluation of Multiple Active Ingredients and Mixtures 

The Agency does not routinely include in its risk assessments 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, they may be used qualitatively or quantitatively in accordance with the 

Agency’s Overview Document and the Services’ Evaluation Memorandum (U.S. EPA 2004; 

U.S. FWS/NMFS 2004). There are four proposed end-use products for the new chemical 

momfluorothrin (for outdoor use); three products contain d-phenothrin and one product contains 

PBO.

2.6.4. Measures of Exposure

Measures of exposure for pesticide risk assessments are typically based on aquatic and terrestrial 

models that estimate environmental concentrations of pesticides using labeled application rates 

and methods for broadcast-applied pesticides. However, since the proposed momfluorothrin 

end-use products are formulated as aerosol spray cans for localized uses and not for large scale 

broadcast applications (e.g. agricultural or mosquito adulticide use) and since the 

momfluorothrin end-use products do not have a maximum label rate, the exposure assessment for 

momflourothrin is qualitative in nature. 

For aquatic exposure estimates, instead of using approaches designed for broadcast applications, 

for momflourothrin EFED estimates the amount of active ingredient that would have to reach a 

water body to result in risk to non-target aquatic organisms and qualitatively discusses the 

likelihood that this might happen. 

Terrestrial exposure estimates for avian and mammalian risk assessments were derived using the 

Terrestrial Residue EXposure model (T-REX) (version 1.5, 03/22/2012). The assumption of the 
-Page 19 of 62-

model is that mammals and birds (surrogates for terrestrial-phase amphibians and reptiles) may 

be exposed via their consumption of treated food items contaminated by direct spray or spray 

drift as a result of application. 

The Screening Imbibition Program (SIP v.1.0) and Screening Tool for Inhalation Risk (STIR 

v.1.0) were used to calculate upper bound estimates of wildlife exposure via drinking water and 

inhalation, respectively, using momfluorothrin’s solubility or vapor pressure, avian and 

mammalian toxicity endpoints.

The Screening Imbibition Program (SIP v.1.0, Released June 15, 2010) was used to calculate an 

upper bound estimate of exposure to wildlife via drinking water using momfluorothrin’s aquatic 

solubility limit [0.933 mg/L], the most sensitive acute avian toxicity endpoint (bobwhite quail 

LD50 >2,250 mg/kg-bw; NOAEC < 241 mg a.i./kg-diet), and the most sensitive acute and 

chronic mammalian toxicity endpoints for momfluorothrin (rat LD50 >2,000 mg/kg-bw, and 

NOAEL = 200 mg a.i./kg-bw, respectively). Drinking water exposure alone was determined not 

to be a potential pathway of concern for avian or mammalian species on an acute basis or 

mammalian species on chronic basis. Although not assessed due to a lack of data, drinking water 

is not expected to be an exposure route of concern for birds from chronic exposure to 

momfluorothrin because acute drinking water exposure is not a potential pathway of 

toxicological concern. For a sample of the output generated by SIP v.1.0, please see 

APPENDIX C. Detailed information about the SIP v.1.0, as well as the tool, can be found on the 

EPA’s website at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial.

The Screening Tool for Inhalation Risk (STIR v.1.0, November 19, 2010) was used to calculate 

an upper-bound estimate of vapor-phase exposure using momfluorothrin’s vapor pressure (1.04 x 

10-8 mm Hg) and molecular weight (385.35 g/mol). STIR incorporates results from several 

toxicity studies including acute oral and inhalation rat toxicity endpoints obtained from the “sixpack” of core studies, which are a series of six guideline studies that are submitted to the 

Registration Division of the Office of Pesticide Programs for technical and formulated products 

of a pesticide [rat acute oral LD50 >2,000 mg a.i./kg-bw (MRID 49020096) and acute inhalation 

LC50 = 1.03 mg/L (MRID 49020103), respectively], as well as the most sensitive acute oral avian 

toxicity endpoint (bobwhite quail LD50 > 2,250 mg a.i./kg-bw). Based on the results of the STIR 

model, inhalation exposure alone was determined not to be a potential pathway of concern for 

avian and mammalian species on an acute inhalation exposure basis (see APPENDIX C for

details). 

2.6.5. Measures of Effect 

Measures of effect are obtained from a suite of registrant-submitted guideline studies that were 

conducted with a limited number of surrogate test species (Table 2.1). No additional ecotoxicity 

data on momfluorothrin were located, based on a July 2014 query of the open literature in the 

publically available version of the ECOTOX database (http://cfpub.epa.gov/ecotox/).

The acute measures of effect used in this baseline assessment are the LD50 (median Lethal Dose), 

LC50 (median Lethal Concentration) or EC50 (median Effects Concentration). These are 
-Page 20 of 62-

measures of acute toxicity which result in 50% of the respective effect in tested organisms. The 

endpoints for chronic measures of exposure are the no observed adverse effect concentration 

(NOAEC) and the no observed adverse effect level (NOAEL). Toxicity studies were submitted 

for freshwater fish and invertebrates, estuarine/marine fish and invertebrates, aquatic plants, 

birds, mammals, bees, and other terrestrial invertebrates. The endpoints used for risk 

characterization are derived from studies which underwent review and were classified as

“acceptable” (conducted under guideline conditions and considered to be scientifically valid) or 

“supplemental” (conditions deviated from guidelines but the results are considered to be 

scientifically valid). 

Table 2.2 lists the measures of environmental exposure and ecological effects used to assess the 

potential risks of momfluorothrin to non-target organisms. The methods used to assess the risk 

are consistent with those outlined in the document “Overview of the Ecological Risk Assessment 

Process in the Office of Pesticide Programs” (USEPA, 2004).
-Page 21 of 62-

Table 2.2. Measures of Exposure and Measures of Effect Used in Assessing Potential Risks 

Associated with the Proposed Uses of Momfluorothrin.

Assessment Endpoint Surrogate Species and Measures of 

Ecological Effect1 Measures of Exposure

Birds2

Survival

Lowest acute LD50 (single oral dose test) 

and LC50 (subacute dietary test)

Upper-bound residues on 

food items

Reproduction 

and Growth

Lowest NOAEC

(21-week reproduction test)

Mammals

Survival Lowest acute LD50 (single oral dose test)

Reproduction 

and Growth

Lowest NOAEC 

(2-generation reproduction test)

Aquatic Animals (Fish and 

invertebrates)3

Survival Lowest tested LC50 or EC50

(acute toxicity test)

Peak EECs

4

Reproduction 

and Growth

Lowest NOAEC (early life-stage or full 

life-cycle tests)

21-day EECs for invertebrates 

and 60-day EECs for fish4

Terrestrial plants5 Survival and 

growth

Lowest EC25 (for non-listed plants) and 

corresponding NOAEC (for listed 

plants)

(endpoints derived for monocots and 

dicots from seedling emergence and 

vegetative vigor studies)

Estimates of runoff and spray 

drift to non-target areas

Terrestrial invertebrates6

Survival 

Lowest honeybee LD50 (acute contact 

toxicity, acute oral toxicity)

Lowest Earthworm LC50

Maximum application rate for 

honeybees and estimates of 

soil concentrations for 

earthworms

Aquatic plants (vascular 

and non-vascular)

Survival and 

growth

Lowest EC50 (for non-listed plants) and 

corresponding NOAEC or EC05 (for 

listed plants)

Peak EECs

4

1 The most sensitive species tested within taxonomic groups is used for screening-level risk assessments.

2 Birds represent surrogates for terrestrial-phase amphibians and reptiles.

3 Freshwater fish represent surrogates for aquatic-phase amphibians.

4 Aquatic EECs are based on modeling described in Section 3.2.2.1.

5 Four species of two families of monocots - one is corn, six species of at least four dicot families, of which one is soybeans.

6 Risk to terrestrial invertebrates from momfluorothrin use is not evaluated, rather the potential hazard to honey bees and earthworms (i.e. the 

available data) are qualitatively assessed. 

2.6.6. Integration of Exposure and Effects

Exposure and toxicity data are integrated in order to evaluate the risks of adverse ecological 

effects on non-target species. Screening-level risk assessments for broadcast-applied pesticides 

use the deterministic risk quotient (RQ) method to compare estimated exposure concentrations 

with measured toxicity values. The RQ method involves dividing point estimates of 

environmental concentrations by acute and chronic toxicity values. The resulting unitless RQs 

are then compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004) (Table 2.3). 

Momfluorothrin, however, is not proposed for broadcast application, and the nature of the 

proposed formulated end-use products (aerosol spray cans) precludes confident identification of

an upper bound application rate. In this screening-level risk assessment for momfluorothrin, 

exposures of risk concern are identified using the LOC and an effort is made to discuss the 

likelihood of the hypothetical exposures occurring. 
-Page 22 of 62-

Table 2.3. 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 EEC1/LC50

2 0.5

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification Peak EEC/LC50 0.1

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

Peak EEC/LC50 0.05

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

chronic exposures

60-day EEC/NOAEC 

(fish)

1

21-day EEC/NOAEC 

(invertebrates)

Aquatic Plants

Non-Listed Potential for effects to non-listed plants from exposures Peak EEC1/LC50

2 1

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC 1

Terrestrial Animals (mammals and birds)

Acute Potential for effects to non-listed animals from acute 

exposures

EEC3/LC50 (Dietary)

0.5

EEC/LD50 (Dose)

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification

EEC/LC50 (Dietary)

0.2

EEC/LD50 (Dose)

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

EEC/LC50 (Dietary)

0.1

EEC/LD50 (Dose)

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

chronic exposures EEC/NOAEC 1

Terrestrial and Semi-Aquatic Plants

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

exposures

EEC3/ EC25 1

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

exposures

EEC/ NOAEC

1

EEC/ EC05

1 Aquatic EECs are based on modeling described in Section 3.2.2.1.

2 LC50 or EC50. 

3 Terrestrial EECs are based on modeling described in Section 3.2.3.1.

3. Analysis

3.1. Use Characterization

Momfluorothrin is proposed for use strictly in the form of hand-held aerosol spray can end use 

products for indoor and outdoor use. Proposed application methods for momfluorothrin include

spot, crack-and-crevice, and wasp and hornet nest treatments only. There are no proposed 

maximum application rates and no restrictions on retreatement intervals. Therefore, this 

assessment qualitatively evaluates potential exposure resulting from outdoor use by considering 

a variety of exposure scenarios. Indoor uses of momfluorothrin products are not considered to 
-Page 23 of 62-

contribute to ecological risk because the potential for outdoor exposure associated with these 

uses is low.

Table 3.1. Proposed Momfluorothrin End-use Product Labels

Label Product Weight

Percent 

Momfluorothrin 

(total grams 

momfluorothrin a.i.)

Other Active 

Ingredient (Percent 

a.i.)

Notes

Sumitomo 

10308-GA

7.1 oz 0.1 (20) d-phenothrin (0.20) No freshwater buffer use 

restriction

MGK-29811 6-20 oz 0.025 (4-14) Cypermethrin (0.05) “For indoor residential use 

only”

MGK-29831 6-20 oz 0.05 (8.5-28) PBO (0.40) “Outdoor applications 

limited to crack-andcrevice or spot surface 

treatments”

MGK-29871 6-20 oz 0.05 (8.5-28) d-phenothrin (0.20) “Outdoor applications 

limited to spot or crackand-crevice and wasp and 

hornet nest treatments... 

Spray [wasp and hornet 

nests] until can is empty”

MGK-29872 6-20 oz 0.05 (8.5-28) d-phenothrin (0.20) Formulated for the utility 

industry;

“Spray [wasp and hornet 

nests] until can is empty”

3.2. Exposure Characterization

3.2.1. Environmental Fate and Transport Characterization

The general physical/chemical properties of momfluorothrin are summarized in Table 3.2. 

Environmental fate and transport properties of momfluorothrin are characterized in further detail 

in the following sections, and data specific to momfluorothrin are noted. The Agency’s 

understanding of these properties is limited by the available dataset. Data submitted using 

momfluorothrin is summarized in Appendix A.

Table 3.2 Chemical Identifiers, Structure, General Physical and Chemical Properties of 

Momfluorothrin.

Parameter Value Reference

PC code 016331 --

CAS No. 609346-29-4 --

Structure --
-Page 24 of 62-

Parameter Value Reference

Chemical name (IUPAC) 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-

(1RS,3RS,1RS,3SR)-3-(2-

cyanoprop-1-enyl)-2,2-

dimethylcyclopropanecarboxylate

--

SMILES code C1(=C(C(=C(C(=C1F)COC(=O)C2C(C2C=C(C#N)C

)(C)C)F)F)COC)F

http://pubchem.n

cbi.nlm.nih.gov/

edit2/index.html

Common name Momfluorothrin (research code: S-1563) --

Chemical formula C19H19F4NO3 --

Molecular weight 385.35 g/mol Leslie and 

Moseley (2010)

Water solubility (20oC, pH 7) 0.933 mg/L Leslie and 

Moseley (2010)

Vapor pressure (25oC) 1.04 x 10-8 Torr (mm Hg) Moseley (2011)

Henry's law constant 1.01 × 10-9atm. m3 mole-1 Foster (2012)

Octanol-water partitioning 

coefficient Log KOW (20oC, pH 7)

2.88 MRID # 

49019924

49019925

Momfluorothrin has a high soil adsorption (Koc ≤ 4344), based on FAO Soil Mobility 

classification and a tendency to partition to sediment in aquatic systems. The reported log 

octanol/water partition coefficient value (2.88) suggests that momfluorothrin has the potential to 

bioaccumulate in aquatic organisms, assuming that chemical metabolism is negligible. 

Momfluorothrin has a molecular weight of 385.3 g/mmol. With a vapor pressure of 1.04x10-8

mm Hg and a limited solubility, the calculated Henry’s Law Constant for momfluorothrin is 

relativiely low (1.01x10-9atm-m3/mol). Table 3.2 lists various important physicochemical 

characteristics of the chemicals. A summary of the submitted environmental fate and transport 

data is provided in Table 3.3.

Laboratory studies have indicated that momfluorothrin degrades through a combination of biotic 

and abiotic reactions and is slightly persistent in the environment. Under acidic and neutral 

conditions this compound is relatively stable to hydrolysis, but it undergoes hydrolysis at pH 9, 

with half-lives of approximately 12 days at 20°C and 7 days at 25°C.

Momfluorothrin is susceptible to aqueous photolysis with a half-life of 32 days. Momfluorothrin

is shown to biodegrade in aerobic soils with half-lives < 5 days, and under aerobic aquatic 

systems with half-lives < 3 days. Momfluorothrin is considered slighltly mobile in soils based on 

the FAO soil mobility classification (Koc as high as 4344 L/Kg) and its potential to leach into 

groundwater is low (USEPA, 2006). If released to water, momfluorothrin will rapidly partition 

to the sediment compartment which acts as an environmental sink for this compound. 

In an acceptable aquatic metabolism study, momfluorothrin appears to degrade rapidly with 

reported half-life < 3 days. Momfluorothrin has low potential to accumulate in fish (log kow < 3). 

The steady-state bioconcentration factors based on the measured [14C] residue concentrations for 

the whole fish were 612 and 600 in the low and high concentration, respectively. The depuration 

half-life for [14C] residue was approximately 9.8 and 12 days in the low and high concentration 
-Page 25 of 62-

levels, respectively.

Table 3.3 Environmental Fate Data Summary for Momfluorothrin plus Degradates 

Observed in Study

Property Value / Degradates observed Reference 

Hydrolysis half-life: pH 5

 pH 7

 pH 9

stable

stable

6.5-7.2 days at pH 9.

MFOA (96.2% AR in alc-RTZ, pH 9 at 50°C) and

Z-CMCA (94.1% AR in acid-RTZ, pH 9 at 40°C).

MRID 

49019941

Aqueous photolysis half-life

Dark-corrected 40°N latitude

31.7 days MRID 

49019943

Aerobic soil metabolism halflife

Alc-labeled RTZ 3.3 day

Acid-labeled RTZ 2 – 4.2 day

Acid-labeled RTE 1.4-4.9 day

14CO2 ranged from 37.0% AR to 51.4% AR at the end 

of the incubation

MRID 

49019947

Aerobic aquatic metabolism 

half-life (total system)

< 3 days 

MFOA-D (maximum of 72.9% of AR)

TFPA detected in both test systems (10.5% AR)

Z-CMCA (83.7% of AR)

Omega c-CONH2-d-t-CRA (21% of AR)

E-CMCA (64.3 % of AR)

MRID 

49019949

Adsorption coefficient

Koc (L/Kg)

4344 (Sediment)

1087– 1213 (Sandy loam)

1063 (loam) 

1033 (Clay loam)

MRID 

48535669

Terrestrial Field Dissipation 

Study

Waived for the proposed use pattern --

Bioconcentration factor 

(BCF) (L/kg)

Edible: 231

Nonedible: 1106

Whole fish: 600

MRID 

48535624

Degradation products under various environmental conditions are shown in Figure 3.1.
-Page 26 of 62-

Figure 3.1. Nomeclature and Structures of Potential Degradation Products of Momfluorothrin
-Page 27 of 62-

3.2.2. Measures of Aquatic Exposure

3.2.2.1. Surface Water Exposure

No drinking water assessment was performed. EFED believes that based on the use pattern (i.e. 

ready-to-use spray cans), while some outdoor exposure is possible, it is unlikely the use will 

yield aquatic exposures that will impact drinking water. For that reason, no quantitative drinking 

water assessment (DWA) has been conducted for these products and this use pattern. EFED 

believes that this evaluation is consistent with previous assessments for this particular outdoor 

use pattern for other pesticides. Should the registrant amend or add to this use pattern, EFED will

reconsider the need for a DWA depending on the nature of the changes (DP Barcode: 410074; 

02/12/2014).

Potential aquatic exposure to momfluorothrin is not quantified directly for the aerosol spray uses

since the proposed use patterns are not comparable in scale to broadcast use patterns (e.g.,

agricultural or public health applications) around which the current exposure models have been 

designed. Instead, EFED estimates the amount of active ingredient that would have to reach a 

water body to result in risk to non-target organisms and qualitatively discusses the likelihood that 

this might happen. The proposed labels state that direct application to water is not allowed. 

Additionally, since this is a new chemical there is no monitoring data.

Exposure estimates were calculated assuming each can contains 500 g product and 0.1% a.i (EPA 

Registration No_10308-GA), and assuming simultaneous release to a pond with water volume of 

20 x 106 L (i.e., standard pond size used in PRZM-EXAMS). Detailed information about the 

standard pond and PRZM and EXAMS models can be found on the EPA’s website at

http://www.epa.gov/opp00001/science/models_pg.htm#aquatic. 

3.2.3. Measures of Terrestrial Exposure

3.2.3.1. Terrestrial Wildlife

Terrestrial exposure estimates for avian and mammalian risk assessments were derived using the 

Terrestrial Residue EXposure model (T-REX) (version 1.5, 03/22/2012). The assumption of the 

model is that mammals and birds (surrogates for terrestrial-phase amphibians and reptiles) may 

be exposed via their consumption of treated food items contaminated by direct spray or spray 

drift as a result of application. Typically, exposure (via pesticide application rate) and toxicity 

(via ecotoxicology test endpoints for birds and mammals) are integrated to determine risk 

quotients. However, since exposure resulting from the proposed momfluorothrin uses is not 

easily quantified, the equation was rearranged to compare the levels of risk concern to avian and 

mammalian ecotoxicology data so as to identify unacceptable acute and chronic environmental 

exposure thresholds. The likelihood of exposures exceeding these thresholds following labeled 

use was qualitatively evaluated. Detailed information about the T-REX model can be found on 

the EPA’s website at:

http://www.epa.gov/oppefed1/models/terrestrial/trex/t_rex_user_guide.htm#Section2_3
-Page 28 of 62-

3.2.3.2. Terrestrial Plants

Terrestrial plant exposure is not considered quantitatively for the proposed momfluorothrin 

aerosol spray can formulations, but is qualitatively discussed in the Risk Description.

3.3. Ecological Effects Characterization

In screening-level ecological risk assessments, effects characterization describes the types of 

effects a pesticide can have on aquatic and terrestrial organisms. This characterization is based 

on the registrant-submitted toxicity data for birds, mammals, fish, aquatic and terrestrial

invertebrates, and aquatic and terrestrial plants for momfluorothrin and a typical formulated enduse product (e.g., momfluorothrin co-formulated with phenothrin, cypermethrin, or PBO). Birds 

are used as surrogates for reptiles and terrestrial-phase amphibians and freshwater fish are used 

as surrogates for aquatic-phase amphibians. 

In addition to the data submitted in support of registration, the public version of ECOTOX 

(ECOTOXicity) database was searched for additional toxicity data from the open literature. The 

ECOTOX database is a publicly-available, quality-assured, comprehensive tool for locating 

toxicity data from the open literature and is maintained by EPA Mid-Continent Ecology 

Division. More information on ECOTOX can be found at: http://www.epa.gov/ecotox. 

Research papers are thoroughly screened using standard procedures before being accepted into 

ECOTOX thereby ensuring consistent, high quality information. For momfluorothrin, no studies 

were identified in ECOTOX as of July 2, 2014.

Given that momfluorothrin is a new active ingredient with no previous registration in the United 

States, it is assumed that no ecological incidents exist for momfluorothrin.

3.3.1. Aquatic Toxicity Assessment

The most sensitive acute and chronic effects measurement endpoints available for

momfluorothrin exposure to freshwater and estuarine/marine species are summarized in Table 

3.13. All acceptable and supplemental studies available for the registration of momfluorothrin 

are described in Appendix B, and the tested material (e.g., momfluorothrin technical, 

momfluorothrin plus phenothrin formulated product) is specified.

3.13. Summary of most sensitive endpoints from submitted aquatic toxicity studies for technical grade 

momfluorothrin. 

Exposure 

Scenario Species Exposure Duration

Toxicity 

Reference 

Value

Effects

Reference / 

Study 

Classification

Toxicity 

Category

Freshwater Fish

Acute Rainbow 

trout

(Oncorhynch

96 hours LC50 = 1.2 μg 

a.i./L

Mortality MRID 49019959

Acceptable

Very Highly 

Toxic
-Page 29 of 62-

3.13. Summary of most sensitive endpoints from submitted aquatic toxicity studies for technical grade 

momfluorothrin. 

Exposure 

Scenario Species Exposure Duration

Toxicity 

Reference 

Value

Effects

Reference / 

Study 

Classification

Toxicity 

Category

us mykiss)

Chronic Fathead 

minnow

(Pimephales 

promelas)

32 days NOAEC = 3.1

μg a.i./L

LOAEC = >3.1

μg ai/L

No effects on 

survival and 

growth

MRID 49019963

Acceptable

Not 

Applicable

Freshwater Invertebrates

Acute Water flea 

(Daphnia 

magna)

48 hours EC50 = 7.8 μg 

a.i./L

Mortality MRID 49019952

Acceptable

Very Highly 

Toxic

Chronic Water flea 

(D.magna)

21 days NOAEC = 3.1 

μg a.i./L

LOAEC = 9.3

μg ai/L

Growth and 

reproduction

MRID 49019961

Acceptable

Not 

Applicable

Benthic Organisms

Chronic Midge 

(Chironomus 

dilutus)

49 days NOAEC < 13 μg 

a.i./kg sediment

(1.8 μg a.i./L 

pore water)

LOAEC = 13 μg 

a.i./kg sediment

Mortality and 

Growth

MRID 49019968

Supplemental, for 

qualitative use 

only

Not 

Applicable

Estuarine/Marine Fish

Acute No data available

Chronic No data available

Estuarine/Marine Invertebrates

Acute

No data available

Chronic No data available

Aquatic Plants

Duckweed (Lemna gibba) 7 days IC50 > 2,500 μg 

a.i./L

NOAEC = 2,500 

μg a.i./L

No toxicity MRID

49019988

Supplemental

Toxicity 

categories are 

not specified 

for plants

Green algae 

(Pseudokirchneriella 

subcapitata)

96 hours IC50 : Could not 

be determined

NOAEC: 370 

μg a.i./L

Potential 

interference 

from co-solvent

confounds 

interpretation of 

treatment 

responses

MRID

49019991

Supplemental, for 

qualitative use 

only

Toxicity 

categories are 

not specified 

for plants

3.3.1.1 Toxicity to Freshwater Fish
-Page 30 of 62-

The acute toxicity of technical grade momfluorothrin to freshwater fish was evaluated in several 

species, with 96-hour LC50 values ranging from 1.2 μg a.i./L in rainbow trout (MRID 49019959) 

to 7.6 μg a.i./L in fathead minnow (MRID 49019957). Based on these results, momfluorothrin is 

categorized as very highly toxic to freshwater fish on an acute basis. 

A study assessing the acute toxicity of one momfluorothrin-plus-phenothrin formulation in 

rainbow trout was also submitted. The momfluorothrin-plus-phenothrin formulation contained 

0.12% w/w momfluorothrin and 0.25% w/w phenothrin. The 96-hour LC50 value reported for 

this product is 2,700 μg formulation/L; 1.3 μg momfluorothrin/L or 6.6 μg phenothrin/L (MRID 

49020222), indicating that this formulated product of momfluorothrin is moderately toxic to 

freshwater fish. This study also indicates that the acute toxicity of momfluorothrin to rainbow 

trout is not enhanced in the mixture compared to exposure to momfluorothrin alone.

An early lifestage study with fathead minnow was submitted by the registrant to establish the 

chronic toxicity of technical grade momfluorothrin to freshwater fish (MRID 49019963). 

Results of this 32-day exposure study showed no significant effects to embryo hatching success, 

the number of live normal larvae at hatch (i.e., larval survial), post hatch survival, total length, 

and dry weight at concentrations up to 3.1 μg a.i./L, yielding a 30-day NOAEC value for survival 

of 3.1 μg a.i./L. 

3.3.1.2. Toxicity to Freshwater Invertebrates

Available acute toxicity studies of momfluorothrin to freshwater invertebrates include a 48-hour 

daphnia test with technical grade momfluorothrin (EC50 of 7.8 μg a.i./L; MRID 49019952) and a 

48-hour daphnia test with formulated product containing a mixture of 0.12% momfluorothrin and 

0.25% phenothrin active ingredients (EC50 of 19,000 μg formulation/L; MRID 49020220). 

Comparison of the 48-hour EC50 values for momfluorothrin TGAI (7.8 μg a.i./L) and 

momfluorothrin formulation (16.5 μg a.i./L) indicates that the formulated product tested has a 

similar order of toxicity to technical grade momfluorothrin. Based on these results, 

momfluorothrin can be categorized as very highly toxic on an acute basis. 

Two chronic toxicity studies with technical grade momfluorothrin were submitted for freshwater 

invertebrates; a 21-day daphnia lifecycle toxicity study (MRID 49019961; acceptable), and a 49-

day midge lifecycle test in a water-sediment system (MRID 49019968; supplemental for 

qualitative use only). Dry weight, length, number of live offspring, time to first brood, and 

successful birth rate were all significantly affected endpoints at the highest concentration tested, 

9.3 μg a.i./L, in the chronic daphnia study. Toxicity values for the sediment toxicity study are

expressed in terms of time-weighted average concentrations of momfluorothrin in sediment (μg 

a.i./kg). The sediment toxicity test with midge determined statistically significant effects to male 

development rate and combined male-female development rate at concentrations as low as 13 μg 

a.i./kg sediment (1.8 μg a.i./L pore water), the lowest test concentration. Since a definitive 

NOAEC value is not available from the chronic midge study, there is increased uncertainty 

surrounding the momfluorothrin toxicity threshold for this taxon.

3.3.1.3. Toxicity to Estuarine/Marine Fish and Invertebrates
-Page 31 of 62-

No acute or chronic estuarine/marine fish or estuarine/marine invertebrate toxicity studies were 

submitted for momfluorothrin. 

3.3.1.4. Toxicity to Aquatic Plants

The 7-day toxicity of technical grade momfluorothrin to aquatic vascular plants was evaluated 

for Lemna gibba, with an IC50 greater than 2,500 μg a.i./L (MRID 49019988; supplemental). The 

96-hour toxicity of technical grade momfluorothrin to aquatic non-vascular plants was evaluated 

for Pseudokirchneriella subcapitata, although an EC50 could not be reliably determined because 

of potential interference from the co-solvent (MRID 49019991; supplemental for qualitative use 

only).

3.3.2 Terrestrial Effects Characterization

The most sensitive acute and chronic toxicity reference values available for momfluorothrin 

exposure to mammals, birds, and terrestrial invertebrates are summarized in Table 3.14. All 

acceptable and supplemental studies available to support the registration of momfluorothrin are 

described in Sections 3.3.2.1. through 3.3.2.4., and the tested material (e.g., momfluorothrin 

technical, momfluorothrin plus phenothrin formulated product) is specified for each study.

Table 3.14 Summary of most sensitive endpoints from submitted terrestrial animal 

toxicity studies for technical grade momfluorothrin. 

Species 

(common 

name)

Taxa 

Represented

Exposure 

Duration Effect Endpoint Reference/ 

Classification

Acute 

Toxicity 

Classification

Laboratory 

Rat (Rattus 

norvegicus)

Mammals

Acute

(oral) Mortality

LD50 > 2,000 

mg a.i./kg-bw*

MRID 

49020096

Acceptable

Practically 

non-toxic

Acute 

(inhalation) Mortality LC50 > 1.03 mg/L*

MRID 

49020103

Acceptable

Practically 

non-toxic

Chronic

Decreased 

F1 and F2 

pup 

weight 

NOAEC = 200 

mg a.i./kg diet

LOAEC = 500 

mg a.i./kg diet

MRID 

49020018

Acceptable

Not 

Applicable

Bobwhite 

quail (Colinus 

virginianus)

Birds, 

terrestrialphase 

amphibians, 

and reptiles

Acute Mortality

LD50 >2,250

mg a.i./kg-bw

MRID 

49019971

Acceptable

Practically 

non-toxic

Zebra finch 

(Poephila

guttata)

Acute Mortality

LD50 > 2,250 

mg a.i./kg-bw

MRID 

49019973

Supplemental

Practically 

non-toxic

Mallard duck

(Anas 

platyrhynchos)

Acute Mortality LC50 >5,620 mg 

a.i./kg diet

MRID 

49019977

Acceptable

Practically 

non-toxic

Bobwhite 

quail (Colinus 

virginianus)

Chronic

Adult 

female 

weight 

gain

NOAEC < 241 

mg a.i./kg diet

LOAEC = 241

mg a.i./kg diet

MRID 

49019979

Supplemental

Not 

Applicable
-Page 32 of 62-

Table 3.14 Summary of most sensitive endpoints from submitted terrestrial animal 

toxicity studies for technical grade momfluorothrin. 

Species 

(common 

name)

Taxa 

Represented

Exposure 

Duration Effect Endpoint Reference/ 

Classification

Acute 

Toxicity 

Classification

Honey bee

(Apis mellifera

L.)

Terrestrial 

invertebrates

Acute Moratlity

Contact LD50 = 

0.2 μg a.i./bee MRID 

49019985

Acceptable

Highly toxic

Acute Mortality

Oral

LD50 = 5.08 μg 

a.i./bee

Not 

Applicable

*Testing was conducted with a 15% a.i. momfluorothrin formulated product, not TGAI.

3.3.2.1. Toxicity to Mammals

Mammalian toxicity data submitted to the Office of Pesticide Programs’ Health Effects Division 

(HED) are used to approximate toxicity to wild mammals. These studies are typically conducted 

with laboratory rats (Rattus norvegicus) or mice (Mus musculus). No studies evaluating toxicity 

to wild mammal species have been submitted to the Agency for momfluorothrin. 

The reported laboratory rat acute oral LD50 value is >2,000 mg/kg-bw for a momfluorothrin 

formulation (15.5% a.i.) (MRID 49020096). Based on the reported laboratory rat oral LD50

value, momfluorothrin is practically non-toxic to small mammals. Acute dermal (MRID 

49020098) testing with rats also determined an LD50 >2,000 mg/kg-bw for momfluorothrin. An 

acute inhalation toxicity study with a momfluorothrin formulation (15.5% a.i.) (MRID 

49020103), while producing no mortalities, found clinical signs included tremor, tremor of tail, 

ataxic gait or urinary incontinence observed in females exposed to 1.03 mg/L.

In the available two-generation rat reproduction study with technical momfluorothrin, the 

NOAEL is 200 mg/kg diet based on decreased F1 and F2 pup body weights (MRID 49020018). 

In the submitted chronic rat dietary study with technical momfluorothrin (MRID 49020020), the 

systemic toxicity LOAEL is 1,500 mg/kg diet (82.6/103.1 mg/kg/day) based on decreases in 

bodyweight and bodyweight gain in females, among other tissue-level effects, and the systemic 

toxicity NOAEL is 500 ppm (76/82 mg/kg/day).

3.3.2.2. Toxicity to Birds

The results of acute oral toxicity testing for momfluorothrin indicates that it is practically nontoxic to avian species on an acute oral basis. The acute oral LD50 value for bobwhite quail 

(Colinus virginianus) is >2250 mg a.i./kg-bw and no clinical signs of toxicity were observed at 

any treatment level (MRID 49019971). Acute oral toxicity of momfluorothrin to a passerine 

species was evaluated with zebra finch (Poephila guttata). The study (MRID 49019973) is 

classified as supplemental because of replacement of two birds in two treatments that 

regurgitated following dosing, but is considered suitable for quantitative use in risk assessment. 

Results of this study indicate that momfluorothrin is practically non-toxic to passerine birds 

(LD50 >2250 mg a.i./kg-bw).

The results of the sub-acute dietary toxicity studies available for momfluorothrin indicate that it 
-Page 33 of 62-

can be categorized as practically non-toxic to avian species on an acute dietary basis. The LC50

for momfluorothrin is greater than 5,620 mg a.i./kg-diet for mallard duck (Anas platyrhynchos) 

(MRID 49019977) and bobwhite quail (MRID 49019975). 

Two avian reproduction studies were received and reviewed for momfluorothrin. In a 

reproduction study with mallard (MRID 49019981), a 37% reduction in the number of eggs laid 

in the highest treatment compared to the negative control resulted in a NOAEC of 483 mg a.s./kg 

diet. In a supplemental reproduction study with bobwhite (MRID 49019979), adult female 

weight gain was significantly reduced compared to the control at the lowest test concentration

such that a no-effect concentration could not be determined. 

3.3.2.3. Toxicity to Terrestrial Invertebrates

The Agency guidelines for terrestrial invertebrate tests are for honey bees (Apis mellifera). The 

acute contact LD50 value for technical grade momfluorothrin is 0.20 μg a.i./bee and the oral LD50

value for technical grade momfluorothrin is 5.08 μg a.i./bee (MRID 49019985). Based on the 

acute contact LD50, momfluorothrin is classified as ‘highly toxic’ to honey bees. 

In addition, the Agency received a honey bee foliar residue toxicity study conducted under the 

Agency guideline (MRID 49020224). The test substance was a momfluorothrin formulated enduse product containing 0.1% momfluorothrin and 0.2% d-phenothrin; the crop treated was 

alfalfa. The RT25 was determined to be less than three hours, alhough it is uncertain whether the 

15 g a.i./ha application rate is representative of exposure that would be expected to result from 

momfluorothrin aerosol use as labeled. 

A sub-acute earthworm toxicity test (MRID 49019983) was also submitted and reviewed. The 

LC50 following a 14-day exposure was determined to be 97.6 mg a.i./kg soil dry weight, and the 

14-day NOAEC was determined to be 15.6 mg a.i./kg soil dry weight based on body weight 

change.

3.3.2.4. Toxicity to Terrestrial Plants

The seedling emergence and vegetative vigor toxicity of momfluorothrin formulated product 

(0.1% a.i. momfluorothrin and 0.2% a.i. d-phenothrin) to terrestrial plants was evaluated for 

monocot (wheat, Triticum aestivum) and dicots (cucumber, Cucumis sativus; cabbage, Brassica 

oleracea; and tomato, Lycopersicon esculentum) in a dual-concentration limit test. Observations 

of phytotoxic response (percentage of necrotic area, effects on plant length, dry weight and 

germination) following exposure to formulated product of momfluorothrin (0.1% a.i.) applied at 

the 500 g/10 m2rate were limited to monocot necrosis; whereas exposure to the same formulated 

product applied at the 5000 g/10 m2rate resulted in observed phytotoxic response encompassing 

reduced germination, necrotic area, and height. The study (MRID 49020227) is classified 

supplemental because of the limited number of crop species tested and because it is uncertain

whether the selected application rates are representative of exposure that would be expected to 

result from labeled momfluorothrin aerosol use. 
-Page 34 of 62-

4. Risk Characterization

4.1. Risk Estimation

Being a qualitative assessment, this analysis does not include standard risk estimation since the 

proposed formulated end-use products (aerosol spray cans) preclude confident identification of 

an upper bound application rate. Instead, exposures of risk concern are identified using the LOC 

and an effort is made to discuss the likelihood of the hypothetical exposures occurring. These 

comparisons of toxicity to exposure are included as part of the risk description. 

4.2. Risk Description

The proposed uses of momfluorothrin are unlikely to adversely affect fish (surrogate species for 

aquatic-phase amphibians) and aquatic invertebrates on both an acute and chronic exposure 

basis, and adverse effects to aquatic plants are not expected. Aquatic risk predictions for fish and 

aquatic invertebrates are low under EFED’s standard exposure scenario due to the nature of the 

proposed uses and aerosol formulations. While much smaller water bodies in close proximity to 

treated areas may have increased vulnerability due to the highly toxic nature of the product, the 

requisite exposure to reach risk levels of concern is unlikely considering that direct application to 

water is prohibited and runoff is mitigated by the labels’ restriction regarding applications near 

surface water (i.e., the 25 foot buffer). Neither is spray drift expected to contribute to aquatic 

exposure, considering the jet spray release feature of the aerosol products proposed for 

registration. Adverse acute and chronic effects to birds (surrogate species for terrestrial-phase 

amphibians and reptiles) and mammals are not expected; neither are effects to terrestrial plants 

expected. While available toxicity data indicate that adverse effects to individual non-target 

insects are likely to result from exposure, exposures of adverse effect threshold magnitude are

likely to be spatially and temporally limited; thus risk to non-target terrestrial invertebrates is 

unlikely. Further, the number of individuals that could be adversely affected during or after spot 

or crack-and-crevice spray treatment are considered to be few in number such that direct adverse 

effects to colony survival are not expected. The magnitude of terrestrial and aquatic exposures 

that can reasonably be expected to result from use of the momfluorothrin aerosol spray products

is the greatest uncertainty in this risk assessment.

4.2.1. Risk to Aquatic Organisms 

Since the proposed use patterns (aerosol spray uses) are not comparable in scale to broadcast use 

patterns (e.g., agricultural or public health applications) around which the current EFED 

exposure models have been designed, model estimated exposure concentrations (EECs) for 

momfluorothrin were not calculated. Instead, EFED estimated the amount of active ingredient 

contained in the runoff from a 10 hectare field that would have to reach a water body to result in 

risk to non-target organisms (referred to as EECs) and qualitatively discusses the likelihood that 

this exposure scenario might occur. The aquatic exposure assessment is conservative in that 

compound fate properties (e.g. degradation, sorption) are not considered during transport to and 

occurrence within the pond.
-Page 35 of 62-

Assuming each can contains 500 g product and 0.1% a.i, if emptied in a pond with water volume 

of 20 x 106 L:

Concentration from one can =

500 mg a. i.

20,000,000 L

= 0.000025 mg a. i./L

 2.5 cans will result in EECs exceeding the acute listed species LOC for fish.

 24 cans will result in EECs exceeding the acute nonlisted species LOC for fish.

 16 cans will result in EECs exceeding the acute listed species LOC for freshwater 

invertebrates.

 It would take more than 150 cans to reach EECs exceeding the acute nonlisted species LOC 

for freshwater invertebrates.

 It would take more than 100 cans before EECs exceed the chronic LOC for freshwater fish 

and (pelagic) invertebrates.

 It would take more than 300 cans before EECs would exceed the listed species LOC for 

aquatic vascular and nonvascular plants.

For example, to calculate the acute listed fish EEC:

LOC ∗ LC50 = EEC

0.05 ∗ 0.0012 mg a. i./L = 0.00006 mg a.i./L

This risk assessment of momfluorothrin shows that aquatic systems are potentially at risk from 

acute and chronic toxic exposure to this chemical. Evaluation of this risk to aquatic organisms 

was approached by dividing the aquatic system into two general compartments, the water column 

and the benthos. 

The first compartment, the water column, which is defined as the aquatic area between surface 

and the benthos (approximately 6 inches above the bottom) represents an area where organisms 

are free-swimming and can feed and breed at the surface, mid water and/or on the benthos 

(sediment). Direct pesticidal contact (e.g., gill lamella, ingestion, and integument) to these 

organisms is assumed to be from the surface water via drift and/or runoff. The toxicity 

assessment points are the acute LC50/ EC50 and chronic NOAEC that are generated through 

standard water column toxicity tests. 

The second aquatic compartment to be considered is the benthos, which is composed of 

sediments and an area 6 inches above the sediment (epibenthos). The benthos is composed of a 

diversity of aquatic invertebrates (e.g., insect larvae, crustaceans, mollusks) and species of fish 

(e.g., catfish, loachs), as well as certain critical life stages of organisms that reside in the water 

column; the benthos is also the initial breeding strata and nursery area for several species of fish, 

especially commercial species such as salmonids. The benthos can also be a source of food 

items for several species of fish that are actively feeding on the organisms in the sediment and/or 

capturing organisms that are emerging from this area.
-Page 36 of 62-

Aquatic Animals: Water Column Exposure

Momfluorothrin is very highly toxic to freshwater fish (surrogate species for aquatic-phase 

amphibians) and aquatic invertebrates on an acute exposure basis. Considering the hypothetical 

discharge of momfluorothrin formulated product directly into the standard EFED 20 million liter 

farm pond, acute listed species LOCs would be exceeded following release of more than two and 

10 cans for freshwater fish and freshwater invertebrates, respectively. While this particular 

exposure scenario (which would qualify as product misuse because of water buffer distance 

restrictions on the proposed labels1) is unlikely to be realized in the environment, it serves to 

illustrate how toxic this active ingredient is to freshwater fish and invertebrates even when 

diluted in a very large volume of water. With a lesser volume receiving water body (e.g., vernal 

pools, small ponds) a correspondingly lesser product volume would result in the same LOC 

exceedances, such that release of the contents of a single can could adversely affect aquatic 

organisms if exposure pathways were complete. However, exposure pathways are not 

considered complete because runoff should be mitigated by the labels’ 25 foot buffer from 

surface water and the limited spray drift associated with the jet spray products.

On a chronic basis, freshwater invertebrate growth and reproduction were found to be adversely 

affected, but the exposure concentrations that would result in RQs exceeding the chronic LOCs 

for freshwater fish and invertebrates are very high; it would take more than 100 cans in the 

EFED farm pond to reach that threshold. Another consideration is that the fathead minnow 

tested in the submitted chronic fish toxicity study was not the most acutely sensitive species 

tested. Employing an acute-to-chronic ratio (ACR) using available acute and chronic fathead 

minnow toxicity endpoints and acute toxicity endpoints for the rainbow trout, the chronic fish 

NOAEC changes from 3.1 μg/L to 0.5 μg/L, a reduction of more than 80%. Using the chronic 

toxicity endpoint determined via the ACR approach, the contents of 20 cans in EFED’s standard 

farm pond would exceed the fish chronic LOC, though, with a lesser volume receiving water 

body (e.g., vernal pools, small ponds) a correspondingly lesser product volume would result in 

chronic LOC exceedances, such that release of the contents of a single can could adversely affect 

aquatic organisms if exposure pathways were complete. However, exposure pathways are not 

considered complete because runoff should be mitigated by the labels’ 25 foot buffer from 

surface water and the limited spray drift associated with the jet spray products.

No acute or chronic toxicity data for estuarine/marine animals were submitted, but considering 

the 25 foot buffer and the anticipated degradation, metabolism, and dilution following release of 

the product— prior to it reaching estuarine/marine habitat areas— risk is considered unlikely. 

Consideration must also be given to the fact that additional toxicity data would not be 

particularly helpful for refining the risk picture for a qualitative assessment such as this one. 

Aquatic Animals: Sediment Exposure

In the absence of a definitive no-effect concentration for chronic testing with the midge, it is not 

possible to confidently identify the threshold of toxicological significance. Compounding the 

risk uncertainty, the magnitude of exposure that might reasonably be expected to result from use 

 

1 The proposed label for EPA Registration No. 10308-GA does not currently restrict application distance from 

freshwater
-Page 37 of 62-

is undefined. Pyrethroids as a class tend to partition to sediments, and tend to be very highly 

toxic to benthic invertebrates; however, the Koc values for momfluorothrin are much lower than 

Koc values for other pyrethroids. Populations of benthic aquatic invertebrates are unlikely to be

adversely affected by labeled use of momfluorothrin aerosol spray products because of limited 

exposure potential. The likelihood of runoff is lessened by the labels’ 25 foot buffer from surface 

water and spray drift resulting from use of the proposed momfluorothrin jet spray products is 

expected to be minimal. Complete exposure pathways for momfluorothrin and aquatic animals 

are unlikely considering that runoff or spray drift would occur at least 25 feet away from aquatic 

receptors, a buffer zone where some combination of sorption, degradation, and/or metabolism

would be expected to substantially reduce bioavailable concentrations. Any momfluorothrin 

entering the water body would be spatially limited and further, subject to dilution. 

Aquatic Plants

Since it would take more than 300 cans being dumped directly into the modeled pond before EECs 

would exceed the listed species LOC for aquatic vascular and nonvascular plants, potential risk to 

aquatic plants from the proposed uses of momfluorothrin is considered to be low. 

4.2.2. Risk to Terrestrial Organisms

There is no maximum application rate currently included on the proposed momfluorothrin enduse product labels; therefore, terrrestrial exposures that would result in RQs exceeding the LOC 

were back-calculated from the LOC using available toxicity data (and only where definitive 

toxicity data were available).

4.2.2.1. Risk to Mammals

The available acute mammalian dose-based toxicity study did not determine a median lethal 

dose. Momfluorothrin is categorized as practically nontoxic to mammals on an acute basis and 

dietary exposure to momfluorothin-treated food items from spray drift or large quantities of 

dispersed product is unlikely. Acute risk to mammals is considered to be low.

The chronic mammalian dietary study determined a no-effect value of 200 mg a.i./kg-diet. In 

order to exceed the chronic LOC of 1, exposure would have to be greater than 200 ppm. Using 

T-REX, it was determined that the application rate would have to be greater than 0.8 lbs a.i./acre 

to exceed the chronic level of concern on a dietary- or dose-basis (Appendix C). An entire 7 

ounce (201 g) aerosol spray can containing 0.1% a.i. momfluorothrin2, if uniformly distributed 

over a 200 square foot area3, would equate to an application rate of 0.09 lb a.i./A. Considering 

the same size foraging area, approximately 9 cans of product would need to be applied for RQs 

to exceed the chronic LOC. Therefore, chronic risk to mammals is likewise considered to be low.

 

2 The active ingredient percentage of the referenced product (EPA Reg. No. 10308-GA) is the highest of all 

proposed momfluorothrin products. It is uncertain whether this label is the most conservative since the other 

proposed product labels have a weight range of 6 to 20 ounces. 

3 The 200 ft2

area is intended to illustrate EECs on a patio-sized area; 200 ft2 was not selected to represent avian or 

mammalian foraging area.
-Page 38 of 62-

4.2.2.2. Risk to Birds

Only non-definitive acute and sub-acute toxicity endpoints are available. Momfluorothrin is

categorized as practically non-toxic to mallard duck, bobwhite quail, and zebra finch on an acute 

and subacute oral and dietary basis. Dietary exposure to food items containing momfluorothinresidues from spray drift or large quantities of dispersed product is unlikely, and acute risk to 

avian species (surrogate species for terrestrial-phase amphibians and reptiles) is expected to be 

low. 

 

Chronic avian reproduction testing with northern bobwhite found effects at all concentrations 

tested. Since a definitive no-effect concentration was not determined, it is not possible to define 

a threshold at which the exposure would not result in risk exceeding the level of concern. 

However, since the upper bound T-REX estimates for short grass would be approximately 21 

ppm for the scenario involving uniform distribution of an entire can’s contents over a 200 square 

foot area (Appendix C), and since 21 ppm is approximately an order of magnitude less than the 

lowest dose tested in the bobwhite avian reproduction study, there is a good margin of safety 

considering that pyrethroids as a class are not known to have chronic avian toxicity concerns. 

Chronic risk to avian species is expected to be low. 

4.2.2.3. Risk to Terrestrial Invertebrates 

Momfluorothrin exposure can be expected to result in acute toxicity to honey bees and is 

considered to be highly toxic on an acute contact (LD50 = 0.2 ug a.i./bee) basis. Based on the 

application rate of 0.09 lb ai/A that was estimated from the application of the product to the 200 

square foot area, acute contact risk to bees can be estimated using methodology described in 

EPA’s guidance for assessing pesticide risks to bees (USEPA, 2014), where:

 

Dose/bee (ug a.i./bee) = application rate (lb a.i./A) * unit contact rate (ug a.i./bee per lb a.i./A)

Dose/bee = 0.09 lb a.i./A * 2.7 ug a.i./bee per lb a.i./A = 0.243 ug a.i./bee

Acute contact RQ = dose/bee / acute contact LD50

Acute contact RQ = 0.243 ug a.i./bee / 0.2 ug a.i./bee = 1.2

Assuming that the 0.09 lb a.i./A application rate is either a reasonable approximation or 

underestimate of exposure, the honey bee acute contact RQ of 1.2 would exceed the acute 

contact LOC of 0.4. But the 0.09 lb a.i./A application rate likely overestimates exposure 

considering that the proposed momfluorothrin products are intented to control target insects 

where they are observed, rather than prophylactic treatment of areas having a sizable footprint, 

such as the hypothetical 200 square foot patio. While exposures potentially higher than 0.09 lb 

a.i./A could occur on a much smaller target area following use of the proposed momfluorothrin 

products (e.g., the wasp and hornet nest killer products where labels instruct the user to “continue 

to spray into nest...until can is empty”), the exposures are generally expected to be limited to 

footprint less than five or 10 square feet in area. Additionally, very limited spray drift would be 
-Page 39 of 62-

expected to result from the wasp and hornet killer products due to the nature of the product 

formulations (i.e., jet spray foam). As the size of the area of exposure concern decreases, the 

likelihood of risk to non-target terrestrial invertebrates also decreases. Considering the small 

exposure areas of concern within the developed land areas and that listed terrestrial invertebrate 

species’ habitat requirements greatly reduce the likelihood of co-occurrence in the developed 

parcels where momfluorothrin products are projected to be used, risk to listed terrestrial 

invertebrates is unlikely. 

Acute oral toxicity testing with the honey bee determined an LD50 of 5.08 ug a.i./bee. So, 

assuming the same 0.09 lb a.i./A application rate:

Exposure =

0.09 lb a. i.

A

×

110 μg

g

×

A

1 lb ×

0.29 g

day

 = 2.87 μg/bee

Acute oral RQ =

2.87

5.08

= 0.57

Assuming that the 0.09 lb a.i./A application rate is either a reasonable approximation or 

underestimate of exposure, the honey bee acute oral RQ of 0.57 would exceed the acute oral

LOC of 0.4. But the 0.09 lb a.i./A application rate likely overestimates exposure, particularly on 

an oral basis, as the probability that listed terrestrial invertebrates would forage in the small 

treated area(s) is low, especially considering that the treated area(s) would unlikely co-occur with

suitable supporting range habitat for listed species. 

In addition to the honey bee acute oral and contact test data, the Agency received a honey bee 

foliar residue toxicity study which indicates that residual toxicity is not of concern for 

momfluorothrin applications less than or equal to 0.013 lb a.i./A (ca. 8% of a single end-use 

product can over an acre area). While available toxicity data indicate that adverse effects to 

individual non-target insect pollinators are likely to result from exposure, exposure is likely to be 

spatially and temporally limited. Thus, the number of individuals that may be adversely affected

during or after spot or crack-and-crevice spray treatment are considered to be few in number 

such that direct adverse effects to colony survival are not expected. Conversely, use of the 

proposed momfluorothrin end-use products to target feral or wild bee hives, such as hives under 

the eaves of a residence, is an ecological risk concern. 

Toxicity information for honey bees is used to develop precautionary label language where 

necessary. Based on the available data, precautionary label language for bees is necessary for 

end-use products with momfluorothrin. No two proposed momfluorothrin product labels share 

the same wording in the environmental hazards section; however, each label should contain the 

following standard language: 
-Page 40 of 62-

“This product is highly toxic to bees exposed to direct treatment on blooming crops or 

weeds. Do not apply this product or allow it to drift to blooming crops or weeds while 

bees are actively visiting the area.” 

Results of a subchronic study with earthworms yielded a 14-day NOAEC of 15.6 mg a.i./kg soil 

for momfluorothrin applied to soil based on bodyweight loss. Based on the toxicity data 

available at this time, acute and chronic risk to non-target terrestrial invertebrates is considered 

unlikely on account of the proposed momfluorothrin uses which have limited exposure potential.

4.2.2.4. Risk to Non-target Terrestrial Plants

The seedling emergence and vegetative vigor toxicity of momfluorothrin formulated product to 

terrestrial plants was evaluated for monocot (wheat, Triticum aestivum) and dicots (cucumber, 

Cucumis sativus; cabbage, Brassica oleracea; and tomato, Lycopersicon esculentum) in a dualconcentration limit test. Observations of phytotoxic response (percentage of necrotic area, 

effects on plant length, dry weight and germination) following exposure to a formulated product 

of momfluorothrin (0.1% a.i.) applied at the 500 g/10 m2rate (ca. 1 to 2.5 cans, depending on 

can size) were limited to monocot necrosis; whereas exposure to the same formulated product

applied at the 5000 g/10 m2rate (ca. 10 to 25 cans, depending on can size) resulted in observed 

phytotoxic response encompassing reduced germination and height, and increased necrotic area. 

The study (MRID 49020227) is classified supplemental because of the limited number of crop 

species tested and because it is uncertain whether the selected application rates are representative 

of exposure that would be expected to result from labeled momfluorothrin aerosol use. The study 

is unsuitable for use in comparing potential exposure concentrations to toxicity values primarily 

because of the uncertain relevance of the selected application rates, but also because of the 

limited number of species tested and limited replication for the species tested.

Risk to terrestrial plants resulting from the proposed aerosol spray uses remain uncertain; 

however, since uniform coverage of foliar surfaces is not expected from the proposed uses, and 

since momfluorothrin is not a systemic compound, adverse phytotoxic response, if observed, is 

expected to be localized on individual plants and spatially limited in plant communities. 

Additional data regarding the toxicity of momfluorothrin to terrestrial plants would not likely 

impact the risk conclusions of this risk assessment; however, additional terrestrial plant toxicity 

testing would be needed to assess the risk to plants from any future broadcast use of 

momfluorothrin.

4.3. Uncertainties and Data Gaps

4.3.2. Effects Uncertainties

The submitted chonic sediment toxicity study did not determine a NOAEC because of 

statistically significant increases in male development rate at the lowest concentration tested. 

Without a definitive NOAEC for sediment dwelling invertebrates, it is unknown how low a 

concentration in water or sediment pore water may elicit adverse effects. A repeated study is not 
-Page 41 of 62-

necessary for the purposes the of this risk assessment because of the proposed use pattern and 

predicted exposure which are presumed to be below the yet-to-be-defined toxicologically 

relevant threshold. 

The submitted northern bobwhite avian reproduction study did not determine a NOAEC because 

of statistically significant growth effects at the lowest concentration tested. While the mallard 

avian reproduction study determined a definitive NOAEC, the upland game bird reproduction 

study remains a data gap under the CFR requirements; however, a repeated upland game bird 

reproduction study is not necessary for the purposes the of this risk assessment because of the 

proposed use pattern and predicted exposure. 

Avian acute oral toxicity testing with a passerine did not determine a NOAEC because of 

regurgitation recorded at the lowest dose tested. Even if the birds that regurgitated the dose were 

counted as mortalities, the LD50 would still be greater than the highest dose tested (2,250 mg/kgbw). This study is considered suitable for quantitative use in this risk assessment.

Terrestrial plant toxicity testing only looked at the response of four crop species in a twoconcentration limit test design. These limit tests are typically designed to encompass the 

response of 10 species. Additional uncertainty lies with the selected application rates of this 

study. While the upper limit dose (ca. 10 or more cans released over a 10 m2area) is likely a 

conservative estimate of exposure that may result from proposed use, this dose did elicit adverse 

response in tested plant species.

A single aquatic nonvascular plant toxicity study is available to assess risk to this taxon. 

Typically four aquatic nonvascular plant studies are conducted to identify interspecies response 

variability. It is uncertain whether the tested species is the most susceptible to momfluorothrinmediated toxicological response of the standard suite of aquatic nonvascular plant surrogates; 

additional aquatic nonvascular plant toxicity data will be needed to assess the risk associated 

with any expansion of use.

No acute or chronic toxicity data for estuarine/marine animals were submitted. The waivers for 

these studies were approved because of the proposed use pattern and associated EECs; however, 

any future submissions for new uses of momfluorothrin will prompt a re-evaluation of the data 

needed for risk assessment.

Although data on the acute toxicity of momfluorothrin is available for the daphnid, the amphipod 

Hyalella azteca is known to be more acutely sensitive to pyrethroids, such as momfluorothrin. 

Thus, the toxicity described in this assessment may underestimate hazard to aquatic 

invertebrates.

5. Federally Threatened and Endangered (Listed) Species Concerns

5.1. Action Area

For listed species assessment purposes, the action area is considered to be the area affected 
-Page 42 of 62-

directly or indirectly by the federal action and not merely the immediate area involved in the 

action. At the initial screening-level, the risk assessment considers broadly described taxonomic 

groups and conservatively assumes that listed species within those broad groups are located on or 

adjacent to the treated site and aquatic organisms are assumed to be located in a surface water 

body adjacent to the treated site. The assessment also assumes that the listed species are located 

within an assumed area that has the relatively highest potential exposure to the pesticide, and that 

exposures are likely to decrease with distance from the treatment area. 

If the assumptions associated with the screening-level action area result in risk quotients that are 

below the listed species LOCs, a "no effect" determination conclusion is made with respect to 

listed species in that taxa, and no further refinement of the action area is necessary. Furthermore, 

risk quotients below the listed species LOCs for a given taxonomic group indicate no concern for 

indirect effects upon listed species that depend upon the taxonomic group covered by the risk 

quotient as a resource. However, in situations where the screening assumptions lead to risk 

quotients in excess of the listed species LOCs for a given taxonomic group, a potential for a 

"may affect" conclusion exists and may be associated with direct effects on listed species 

belonging to that taxonomic group or may extend to indirect effects upon listed species that 

depend upon that taxonomic group as a resource. In such cases, additional information on the 

biology of listed species, the locations of these species, and the locations of use sites could be 

considered to determine the extent to which screening assumptions regarding an action area 

apply to a particular listed organism. These subsequent refinement steps could consider how this 

information would affect the action area for a particular listed organism and may potentially 

include areas of exposure that are downwind and downstream of the pesticide use site.

5.2. Taxonomic Groups Potentially at Risk 

The Level I screening assessment process for listed species uses the generic taxonomic groupbased process to make inferences on direct effect concerns for listed species. The first iteration 

of reporting the results of the Level I screening is a listing of pesticide use sites and taxonomic 

groups for which RQ calculations reveal values that meet or exceed the listed species LOCs or 

other evidence suggests that adverse effects are likely or cannot be precluded (for more 

information see, USEPA, 2004). 

The Agency acknowledges that pesticides have the potential to exert indirect effects upon listed 

organisms by, for example, perturbing forage or prey availability, altering the extent of nesting 

habitat, and creating gaps in the food web. In conducting a screen for indirect effects, direct 

effect LOCs for each taxonomic group are used to make inferences concerning the potential for 

indirect effects upon listed species that rely upon non-listed organisms in these taxonomic groups 

as resources critical to their life cycle.

For the proposed aerosol spray can uses of momfluorothrin, predicted environmental exposures 

result in RQs less than the listed species LOCs and a “no effect” determination is made (Table 

5.1).
-Page 43 of 62-

Table 5.1. Potential Effects to Federally Listed Taxa Associated with Direct or Indirect 

Effects from the Proposed Uses of Momfluorothrin.

Listed Taxon Direct Effects Indirect Effects

Terrestrial and semi-aquatic plants - monocots No No

Terrestrial and semi-aquatic plants - dicots No No

Birds No No

Terrestrial-phase amphibians and reptiles No No

Mammals No No

Terrestrial invertebrates No No

Aquatic nonvascular plants No No

Aquatic vascular plants No No

Freshwater fish No No

Aquatic-phase amphibians No No

Freshwater crustaceans No No

Mollusks No No

Marine/estuarine fish No No

Marine/estuarine invertebrates No No

5.2.1. Probit Dose-Response Analysis 

The Agency uses the probit dose-response relationship as a tool for providing additional 

information on the potential for acute direct effects to aquatic and terrestrial animals (USEPA, 

2004); however, individual effect chance probabilities are of limited value to a qualitative risk 

assessment and have been excluded. 
-Page 44 of 62-

6. References

Habig, C. 2012. S-1563: An Ecological Risk Assessment. Compliance Services International on 

behalf of Sumitomo Chemical Company, LTD. 40p.

Matsumura, F. 1985. Toxicology of Insecticides. 2nd ed. New York. Plenum Press. 147p.

USEPA 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. Published in 

63 FR 26846; May 14, 1998. U.S. Environmental Protection Agency, Washington, DC. 

April, 1998.

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

Programs, U.S. Environmental Protection Agency. Endangered and Threatened Species 

Effects Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of 

Pesticide Programs, Washington, D.C. January 23, 2004. Online at: 

http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf

USEPA 2006. Standardized Soil Mobility Classification Guidance. U.S. Environmental 

Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of 

Pesticide Programs, Environmental Fate and Effects Division, Memorandum. Apr. 21, 

2006.

USEPA. 2011. Water Models. U.S. Environmental Protection Agency, Pesticides: Science and 

Policy, Models and Databases. Last updated Aug. 8, 2011. Online at: 

http://www.epa.gov/oppefed1/models/water/

USEPA 2014. Guidance for Assessing Pesticide Risks to Bees. U.S. Environmental Protection 

Agency, Office of Pesticide Programs, Environmental Fate and Effects Division, June 19, 

2014.

USFWS/NMFS. 2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act Section 7 

Consultation Regulations; Final Rule. FR 47732-47762.

Urban, D.J. and N.J. Cook, 1986. Hazard Evaluation Division Standard Evaluation Procedure 

Ecological Risk Assessment. EPA 540/9-85-001. U.S. Environmental Protection 

Agency, Office of Pesticide Programs, Washington D.C.
-Page 45 of 62-

6.1. Submitted Environmental Fate and Transport Studies

Submitted Environmental Fate and Transport Studies

MRID

49019926 Leslie, S.; Moseley, R. (2010) S-1563: Development and Validation of an Analytical 

Method, and Evaluation of the Water Solubility: Final Report. Project Number: 

RWP/0006, 1004649, 8226997. Unpublished study prepared by Covance 

Laboratories, Ltd. 58p.

49019927 Leslie, S.; Moseley, R. (2010) S-1563RTZ: Development and Validation of an 

Analytical Method, and Evaluation of the Water Solubility: Final Report. Project 

Number: RWP/0007, 1004649, 8228972. Unpublished study prepared by Covance 

Laboratories, Ltd. 63p.

49019928 Leslie, S.; Moseley, R. (2010) S-1563RTE: Development and Validation of an 

Analytical Method, and Evaluation of the Water Solubility: Final Report. Project 

Number: RWP/0008, 1004649, 8228971. Unpublished study prepared by Covance 

Laboratories, Ltd. 63p.

49019924 Wright, D.; Moseley, R. (2011) S-1563RTZ: Determination of Octanol: Water 

Partition Coefficient: Final Report. Project Number: RWP/0024, 1004649, 8226996. 

Unpublished study prepared by Covance Laboratories, Ltd. 69p.

49019925 Wright, D.; Moseley, R. (2011) S-1563RTE: Determination of Ocatanol: Water 

Partition Coefficient: Final Report. Project Number: RWP/0025, 1004649, 8239094. 

Unpublished study prepared by Covance Laboratories, Ltd. 70p.

835.2120 Hydrolysis 

MRID Citation Reference

49019941 Ponte, M. (2011) Hydrolysis of [(Carbon 14)]S-1563 in Buffered Aqueous 

Solutions. Project Number: RWM/0012, 2055W, 2055W/001. Unpublished 

study prepared by PTRL West, Inc. 309p.

835.2240 Aqueous photolysis

MRID Citation Reference
-Page 46 of 62-

49019943 Ponte, M.; Ponte, V. (2012) Photodegradation of [(Carbon 14)]S-1563 in 

Aqueous Solution Buffered at pH 4 by Artificial Light. Project Number: 

RWM/0014, 2056W. Unpublished study prepared by PTRL West, Inc. 

241p.

835.4100 Aerobic soil metabolism

MRID Citation Reference

49019947 Ponte, M. (2012) Aerobic Soil Metabolism of [(Carbon 14)]S-1563 in Four 

Soils. Project Number: RWM/0015, 2052W, 2052W/1. Unpublished study 

prepared by PTRL West, Inc. 555p.

835.4300 Aerobic aquatic metabolism

MRID Citation Reference

49019949 Ponte, M.; Mannella, L. (2011) [(Carbon 14)]S-1563: Degradation in Water 

Sediment System under Aerobic Conditions. Project Number: RWM/0011, 

2054W, 2054W/1. Unpublished study prepared by PTRL West, Inc. 385p.

850.1730 Fish BCF

MRID Citation Reference

49019966 Kang, S. (2012) Flow-Through Biocencentration and Metabolism Study of 

[(Carbon 14)]S-1563 with Bluegill sunfish (Lepomis macrochirus). Project 

Number: RWW/0025, 13048/6668. Unpublished study prepared by 

Smithers Viscient Laboratories. 238p.

835.1230 Sediment and soil absorption/desorption for parent and degradates

MRID Citation Reference

49019936 Ponte, M. (2012) Soil Adsorption/Desorption of [(Carbon 14)]S-1563 by the 
-Page 47 of 62-

Batch Equilibrium Method. Project Number: RWM/0016, 2059W, 

2059W/1. Unpublished study prepared by PTRL West, Inc. 315p.

835.1240 Soil column leaching

MRID Citation Reference

49019939 Ponte, M. (2011) Estimation of the Adsorption Coefficient (Koc) of S1563RTZ and S-1563RTE Using High Performance Liquid 

Chromatography. Project Number: RWM/0010, 2101W. Unpublished study 

prepared by PTRL West, Inc. 39p.

835.6100 Terrestrial field dissipation

MRID Citation Reference

49019951 Habig, C. (2012) S-1563: Waiver Request from Further 

Testing: Terrestrial Field Dissipation. Project Number: 

RWM/0018, 650/02/112012/05. Unpublished study prepared 

by Compliance Services International. 16p.

Non Guideline Studies

49019945 Nishimura, H.; Suzuki, Y.; Fujisawa, T.; et al. (2011) Stability of S-1563 in Air 

(Calculation by Atkinson's Method). Project Number: RWP/0033, STA2011A, 

EF/2011/040. Unpublished study prepared by Sumitomo Chemical Company. 8p.

6.2. Submitted Ecotoxicity Studies

850.1010 Aquatic invertebrate acute toxicity, test, freshwater daphnids

MRID Citation Reference

49019952 Fournier, A. (2011) S-1563 - Acute Toxicity to Water Fleas (Daphnia magna) Under 

Flow-Through Conditions. Project Number: RWW/0012, 13048/6657. Unpublished 

study prepared by Smithers Viscient Laboratories. 104p.

49020220 Fournier, A. (2012) S-1563/Sumithrin WBA (USA) Bulk Formulation - Acute Toxicity to 
-Page 48 of 62-

Water Fleas (Daphnia magna) Under Static-Renewal Conditions. Project Number: 

RWW/0033/OCR, 13048/6712. Unpublished study prepared by Smithers Viscient 

Laboratories. 205p.

850.1075 Fish acute toxicity test, freshwater and marine

MRID Citation Reference

49019954 Fournier, A. (2011) S-1563 - Acute Toxicity to Bluegill Sunfish (Lepomis macrochirus) 

Under Flow-Through Conditions. Project Number: RWW/0015, 13048/6654. 

Unpublished study prepared by Smithers Viscient Laboratories. 101p.

49019956 Habig, C. (2012) S-1563: Request for a Waiver from Acute Toxicity Testing with 

Estuarine and Marine Organisms. Project Number: RWW/0028, 650/02/112012/01. 

Unpublished study prepared by Compliance Services International. 16p.

49019957 Fournier, A. (2011) S-1563 - Acute Toxicity to Fathead Minnow (Pimephales 

promelas) Under Flow-Through Conditions. Project Number: RWW/0014, 

13048/6656. Unpublished study prepared by Smithers Viscient Laboratories. 105p.

49019959 Fournier, A. (2011) S-1563 - Acute Toxicity to Rainbow Trout (Oncorhynchus mykiss) 

Under Flow-Through Conditions. Project Number: RWW/0013, 13048/6655. 

Unpublished study prepared by Smithers Viscient Laboratories. 108p.

49020222 Fournier, A. (2012) S-1563/Sumithrin WBA (USA) Bulk Formulation - Acute Toxicity 

(LC50) with Rainbow Trout (Oncorhynchus mykiss) Under Static-Renewal Conditions. 

Project Number: RWW/0026/OCR, 13048/6713. Unpublished study prepared by 

Smithers Viscient Laboratories. 224p.

850.1300 Daphnid chronic toxicity test

MRID Citation Reference

49019961 Fournier, A. (2012) S-1563 - Full Life Cycle Toxicity Test with Water Fleas (Daphnia 

magna) Under Flow-Through Conditions. Project Number: RWW/0024, 13048/6661. 

Unpublished study prepared by Smithers Viscient Laboratories. 210p.

850.1400 Fish early-life stage toxicity test

MRID Citation Reference

49019963 York, D. (2012) S-1563 - Early Life-Stage Toxicity Test with Fathead Minnow, 

Pimephales promelas. Project Number: RWW/0021, 13048/6709. Unpublished study 

prepared by Smithers Viscient Laboratories. 183p.

850.2100 Avian acute oral toxicity test

MRID Citation Reference

49019971 Hubbard, P.; Beavers, J. (2010) S-1563: An Acute Oral Toxicity Study with the 

Northern Bobwhite. Project Number: RWW/0002, 166/193. Unpublished study 

prepared by Wildlife International, Ltd. 69p.

49019973 Hubbard, P.; Beavers, J. (2010) S-1563: An Acute Oral Toxicity Study with the Zebra 

Finch (Poephila guttata). Project Number: RWW/0007, 166/194. Unpublished study 

prepared by Wildlife International, Ltd. 68p.
-Page 49 of 62-

850.2200 Avian dietary toxicity test

MRID Citation Reference

49019975 Hubbard, P.; Martin, K.; Beavers, J. (2011) S-1563: A Dietary LC50 Study with the 

Northern Bobwhite. Project Number: RWW/0011, 166/195. Unpublished study 

prepared by Wildlife International, Ltd. 86p.

49019977 Hubbard, P.; Martin, K.; Beavers, J. (2011) S-1563: A Dietary LC50 Study with the 

Mallard. Project Number: RWW/0010, 166/196. Unpublished study prepared by 

Wildlife International, Ltd. 86p.

850.2300 Avian reproduction test

MRID Citation Reference

49019979 Temple, D.; Martin, K.; Beavers, J.; et al. (2012) S-1563: A Reproduction Study with 

the Northern Bobwhite: Final Report. Project Number: RWW/0019, 166/200. 

Unpublished study prepared by Wildlife International, Ltd. 223p.

49019981 Temple, D.; Martin, K.; Beavers, J.; et al. (2012) S-1563: A Reproduction Study with 

the Mallard: Final Report. Project Number: RWW/0020, 166/201. Unpublished study 

prepared by Wildlife International, Ltd. 221p.

850.3030 Honey bee toxicity of residues on foliage

MRID Citation Reference

49020224 Kling, A. (2012) X-6935-12: Residual Toxicity to the Honey Bee (Apis mellifera L.) 

under Extended Laboratory Conditions When Applied as a Foliar Spray to Alfalfa 

Leaves. Project Number: RWW/0034/OCR, X/6935/12, S12/03547. Unpublished 

study prepared by Eurofins - GAB GmbH. 134p.

850.4300 Terrestrial plants field study

MRID Citation Reference

49020227 Saito, S. (2010) Phytotoxicity Study of S-1563 WBA (Wasp & Hornet Insecticide 

Aerosol). Project Number: RWW/0005/OCR. Unpublished study prepared by 

Sumitomo Chemical Co. 19p.

850.4400 Aquatic plant toxicity test using Lemna spp. 

MRID Citation Reference

49019988 Softcheck, K. (2012) S-1563 - 7-Day Toxicity Test with Duckweed (Lemna gibba). 

Project Number: RWW/0023, 13048/6708. Unpublished study prepared by Smithers 

Viscient Laboratories. 182p.

850.5400 Algal toxicity

MRID Citation Reference

49019991 Softcheck, K. (2011) S-1563 - 96-Hour Toxicity Test with the Freshwater Green Alga, 

Pseudokirchneriella subcapita. Project Number: RWW/0018, 13048/6663. 
-Page 50 of 62-

Unpublished study prepared by Smithers Viscient Laboratories. 153p.
-Page 51 of 62-

Appendix A. Sumary of Environmental Fate Data for Momfluorothrin

835.2120 Hydrolysis (MRID 49019941)

Ponte, M. (2011) Hydrolysis of [(Carbon 14)]S-1563 in Buffered Aqueous Solutions. Project 

Number: RWM/0012, 2055W, 2055W/001. Unpublished study prepared by PTRL West, Inc. 

309p.

The hydrolysis of [14C]S-1563 was studied at pH 4, 7 and 9 incubated at temperatures between 25°C and 60°C. S1563 was stable to hydrolysis in pH 4 buffers following a preliminary study conducted at 50°C for 5 days. Preliminary 

hydrolysis studies conducted with S-1563RTZ and S-1563RTE showed that there were insignificant differences in the 

hydrolysis rates and degradation pathways for the different isomers. No isomerisation was observed at any of the pH 

tested. 

In the definitive study, the hydrolysis of S-1563RTZ in pH 7 buffer was conducted at three temperatures, 40, 50 and 

60°C for up to 33 days. Similarly, the hydrolysis of S-1563RTZ in pH 9 buffer was conducted at three temperatures, 

25, 40 and 50°C for up to 21 days. The rate of hydrolysis of S-1563RTZ in pH 7 and pH 9 samples was dependent on 

temperature and pH. 

The major degradates observed were MFOA (96.2% AR in alc-RTZ, pH 9 at 50°C) and Z-CMCA (94.1% AR in acidRTZ, pH 9 at 40°C). The DT50 at 25°C were determined to be 381-726 days at pH 7 and to be 6.5-7.2 days at pH 9.

835.2130 Aqueous Photolysis (MRID 49019943)

Ponte, M.; Ponte, V. (2012) Photodegradation of [(Carbon 14)]S-1563 in Aqueous Solution 

Buffered at pH 4 by Artificial Light. Project Number: RWM/0014, 2056W. Unpublished study 

prepared by PTRL West, Inc. 241p.

A photolysis study was conducted with three radiolabels of S-1563 in sterile pH 4 buffered solution at 0.3 μg/mL 

using < 1% acetonitrile as co-solvent. The average integrated intensity of the light source for the 300-400 nm and 

300-800 nm ranges were 48.6 and 443 W/m2, respectively for 13 days. Using the irradiance at wavelengths of 300-

800 nm during the irradiation period, 10.2 hours of exposure are equivalent to 1 day of natural sunlight (summer 

40°N latitude). Light exposed and dark control samples were maintained at a temperature of 25 ± 2°C. S-1563 

degraded rapidly in pH 4 buffer solutions when exposed to artificial light and represented approximately 50% AR in 

the three sets following 13 days of exposure. Appropriate controls confirmed that it was stable to hydrolysis and there 

was no significant isomerization in darkness. The main degradates observed were CMCA and MFOA via cleavage 

of the ester linkage. CMCA represented 30.9-38.8% AR in the acid label sets with its trace amounts of isomers, and 

MFOA represented up to an average of 26.6% AR in the alcohol label set by the end of the study period. Isomerization 

of S-1563RTZ or S-1563RTE to the other 7 isomers was observed throughout the study in light exposed samples, 

but none of the other isomers represented > 4.7% AR. The half-life of S-1563 (sum of eight isomers) in light exposed 

samples was determined to be 31.7 U.S. solar days (25.9 OECD solar days) for the three sets tested. The 

photodegradation rates of S-1563 including its photo-isomerisation were almost the same in S-1563RTZ and S1563RTE with their half-lives of 17.6 U.S. solar days (14.5 OECD solar days). The quantum yield of S-1563 (sum 

of eight isomers) was determined as 0.0113. The quantum yield of S-1563 including its photoisomerization was 

estimated to be 0.0205, using the photodegradation rate constants for S-1563RTZ/S-1563RTE (mean 0.0943days-1).

835.4100 Aerobic soil metabolism (MRID 49019947)

Ponte, M. (2012) Aerobic Soil Metabolism of [(Carbon 14)]S-1563 in Four Soils. Project 
-Page 52 of 62-

Number: RWM/0015, 2052W, 2052W/1. Unpublished study prepared by PTRL West, Inc. 

555p.

An aerobic soil metabolism study was conducted with three radiolabels: [acid14C]S-1563RTZ [cyclopropyl-1-

14C]S1563RTZ (1R-trans-Z isomer), [alc14C]S-1563RTZ [methoxybenzyl-α14C]S-1563RTZ (1R-trans-Z isomer), and 

[acid14C]S-1563RTE [cyclopropyl-1-

14C]S-1563RTE (1R-trans-E isomer) on four agricultural soils. For the route 

study, the three radiolabels were applied to individual samples of a Sharkey silt loam soil. For the rate studies, 

individual samples of HCB loam, APSL sandy loam and APCL clay loam soils were dosed with [acid14C]S-1563RTZ 

and [acid14C]S-1563RTE. The final dose rate for the study was approximately 2 μg/g.

Samples were incubated at pF 2~2.5 in the dark at 20 °C for up to 122 days. The soil samples were continuously 

aerated throughout the incubation period. Traps for volatiles included an ethylene glycol trap to collect organic 

volatiles and 10% aqueous NaOH traps to collect CO2. Soil samples were extracted three times with a neutral solvent 

(acetone/water, 9/1, v/v) followed by two acidic solvent extractions (acetone/0.5 M HCl, 5/1, v/v) and one acetone 

extraction. S-1563 and degradates were quantified by reverse phase high performance liquid chromatography (HPLC) 

of neutral and acidic soil extracts with co-injection of a mixed solution of analytical reference standards. 

Radiocarbon recoveries were calculated as a percent of applied radiocarbon (AR) and ranged from an average of 92.8

± 2.3% to an average of 96.1 ± 6.9% for the all sample sets.

Bound residues for selected samples in the acid-RTZ and acid-RTE sets were further characterized by humic 

acid/fulvic acid partition. Radiocarbon associated with the fulvic acids ranged 1.5% AR to 11.3% AR for all sets, 

while radiocarbon associated with the humic acids ranged from 4.9% AR to 11.8% AR for all sets. Radiocarbon 

remaining bound to the humins represented the biggest portion for all sample sets and ranged from 15.3% AR to 

39.0% AR for all samples tested.

835.1230 Batch Equilibrium, Adsorption/desorption (MRID 49019936)

Ponte, M. (2012) Soil Adsorption/Desorption of [(Carbon 14)]S-1563 by the Batch 

Equilibrium Method. Project Number: RWM/0016, 2059W, 2059W/1. Unpublished study 

prepared by PTRL West, Inc. 315p.

Adsorption and desorption of [14C]S-1563RTZ was studied on four soils and one sediment using the batch 

equilibrium method (pH (CaCl2) range 5.65 to 7.3, %OC 0.32 – 4.0). Isomerisation was determined and showed 

that it was insignificant during the experiment. No significant difference in adsorption/desorption behaviour 

between the RTZ and RTE isomer was observed in the preliminary studies and therefore the definitive study was 

conducted with the RTZ isomer only. Adsorption Kads (Kf) values ranged from 4.85 to 42.5. KOC values ranged 

from 1033 to 4344 (average = 1748, n=5). These KOC values show that S-1563RTZ has a low mobility. 

Desorption Kdes values ranged from 9.03 to 53.5. The KOC values for desorption ranged from 1085 to 6219 (average 

= 2484, n=5), indicating that once adsorbed to the soil S-1563RTZ is not likely to be removed.

There was no evidence of any pH dependence.

835.4300 Aerobic Aquatic Metabolism (MRID 49019949)

Ponte, M.; Mannella, L. (2011) [(Carbon 14)]S-1563: Degradation in Water Sediment System 

under Aerobic Conditions. Project Number: RWM/0011, 2054W, 2054W/1. Unpublished 

study prepared by PTRL West, Inc. 385p.
-Page 53 of 62-

An aerobic aquatic metabolism study was conducted with three radiolabels of [14C]S-1563 applied to two freshly 

collected sediment/water systems (Abbey and Swiss) per radiolabel. The radiolabels included [acid14C]S-1563RTZ 

[cyclopropyl-1-

14C]S-1563RTZ (1R-trans-Z isomer), [alc14C]S-1563RTZ [methoxybenzyl-α14C]S-1563RTZ (1Rtrans-Z isomer), and [acid14C]S-1563RTE [cyclopropyl-1-

14C]S-1563RTE (1R-trans-E isomer). Individual 

sediment/water samples were treated with [14C]S-1563 with 7.7-8.4 μg per sample for both test systems and incubated 

under aerobic conditions at 20 ± 2 °C in the dark. All samples were then incubated for up to 105 days for [acid14C]S1563RTZ and [acid14C]S-1563RTE samples and 146 days for [alc14C]S-1563RTZ samples. [

14C]S-1563 degraded 

rapidly in both test systems throughout the study period and represented < 4% AR after 8 days of incubation. DT50

and DT90 values were calculated as < 3 days and < 10 days respectively. Likewise, the rate of dissipation of [14C]S1563 was rapid in the water layer representing < 3 days for DT50 and < 9 days for DT90.

The main degradates of [alc14C]S-1563RTZ were MFOA-D (maximum of 72.9% of AR at day 100 in Abbey and 

74.5% at day 15 in Swiss) and TFPA detected in both test systems (10.5% AR in Abbey at day 100 and 67.5% in 

Swiss at the end of incubation period) and MFOA detected in Abbey test system only >10% AR (35% at day 8). Other 

degradates observed during the incubation period were S-1563RTZ-CONH2.

The primary degradates of [acid14C]S-1563RTZ were Z-CMCA (83.7% at day 8 in Abbey and 72% at day 8 in Swiss) 

followed by ωc-CONH2-d-t-CRA and t-COOH-CA (max. averages of 21.0% AR (Swiss, day 100) and 10.3% AR 

(Abbey, day 58)). S-1563RTZ-CONH2 was observed at levels of 8%. E-CMCA represented the main degradate of 

[acid14C]S-1563RTE, with maximum averages of 64.3 % AR at day 7 in Abbey and 59.8% AR at day 30 in Swiss, 

followed by two other important degradates, ωt-CONH2-d-t-CRA and t-COOH-CA (max. average of 31.7% and 

26.1% after 100 days in Swiss and 20.1% and 21.5% AR respectively at day 59 in Abbey). Other minor degradates 

observed were S-1563RTE-CONH2 and ωt-COOH-d-t-CRA.

No isomerisation was observed for S-1563RTZ and RTE

850.1730 Fish BCF (MRID 49019966)

Kang, S. (2012) Flow-Through Biocencentration and Metabolism Study of [(Carbon 14)]S1563 with Bluegill sunfish (Lepomis macrochirus). Project Number: RWW/0025, 

13048/6668. Unpublished study prepared by Smithers Viscient Laboratories. 238p.

The bioconcentration potential of S-1563 to bluegill sunfish was evaluated using [Benzyl14C]S-1563 which consists 

of two geometrical isomers, S-1563RTE and S-1563RTZ. The study was conducted to measure the uptake and 

depuration of S-1563 and steady-state bioconcentration factor (BCF). Bluegill sunfish were exposed to [Benzyl14C]S-1563 using a flow-through system, at concentrations of 0.1 and 0.3 μg a.s./L. Fish were exposed to the test 

concentrations for a total of 35 days. For the elimination of [

14C]residues (depuration), the test fish were placed in 

clean water for 28 days. The major findings of the study are as follows.

 A steady state was reached by exposure Day 35.

 S-1563 was stable in water; however, rapidly metabolized in fish and was not detected after exposure Day 1.

 The depuration half-life for [14C]residues was approximately 9.8 and 12 days in the low and high concentration 

levels, respectively. 

 The steady-state bioconcentration factors based on the measured [

14C]residue concentrations for the whole fish 

were 612 and 600 in the low and high concentration fish, respectively.
-Page 54 of 62-

Appendix B. Sumary of Ecological Effects Data for Momfluorothrin

Table 1. Summary of Submitted Aquatic Toxicity Studies for Momfluorothrin. 

Exposure Scenario Species Exposure 

Duration

Toxicity Reference 

Value Effects

Reference / 

Study Classification / 

Formulation

Toxicity 

Category

Freshwater Fish

Acute Rainbow trout

(Oncorhynchus 

mykiss)

96 hours LC50 = 1.2 μg a.i./L Mortality MRID 49019959

Acceptable

TGAI

Very Highly Toxic

Acute Rainbow trout

(O. mykiss)

96 hours LC50 = 1.3 μg a.i./L Mortality MRID 49020222

Supplemental

Formulated product 

(0.12% a.i.)

Very Highly Toxic

Acute Bluegill sunfish 

(Lepomis 

macrochirus)

96 hours LC50 = 3.0 μg a.i./L Mortality MRID 49019954

Acceptable

TGAI

Very Highly Toxic

Acute Fathead minnow 

(Pimephales 

promelas)

96 hours LC50 = 7.6 μg a.i./L Mortality MRID 49019957

Supplemental

TGAI

Very Highly Toxic

Chronic Fathead minnow

(P. promelas)

32 days NOAEC = 3.1 μg a.i./L

LOAEC = >3.1 μg ai/L

No effects on survival 

and growth

MRID 49019963

Acceptable

TGAI

Not Applicable

Freshwater Invertebrates

Acute Water flea 

(Daphnia magna)

48 hours EC50 = 7.8 μg a.i./L Mortality MRID 49019952

Acceptable

TGAI

Very Highly Toxic
-Page 55 of 62-

Table 1. Summary of Submitted Aquatic Toxicity Studies for Momfluorothrin. 

Exposure Scenario Species Exposure 

Duration

Toxicity Reference 

Value Effects

Reference / 

Study Classification / 

Formulation

Toxicity 

Category

Acute Water flea

(D. magna)

48 hours EC50 = 16.5 μg a.i./L Mortality MRID 49020220

Supplemental

Formulated product 

(0.12% a.i.)

Very Highly Toxic

Chronic Water flea 

(D.magna)

21 days NOAEC = 3.1 μg a.i./L

LOAEC = 9.3 μg ai/L

Growth and reproduction MRID 49019961 

Acceptable

TGAI

Not Applicable

Benthic Organisms

Chronic Midge (Chironomus 

dilutus)

49 days NOAEC < 13 μg a.i./kg 

sediment (1.8 μg a.i./L 

pore water)

LOAEC = 13 μg a.i./kg 

sediment

Mortality and Growth MRID 49019968

Supplemental, for 

qualitative use only

TGAI

Not Applicable

Aquatic Plants

Duckweed (Lemna gibba) 7 days IC50 > 2,500 μg a.i./L

NOAEC = 2,500 μg 

a.i./L

No toxicity MRID 49019988

Supplemental

TGAI

Toxicity categories 

are not specified for 

plants

Green algae (Pseudokirchneriella subcapitata) 96 hours IC50 : Could not be 

determined

NOAEC: 370 μg a.i./L

Potential interference 

from co-solvent

confounds interpretation 

of treatment responses

MRID 49019991

Supplemental, for 

qualitative use only

TGAI

Toxicity categories 

are not specified for 

plants

Note: No data available for estuarine/marine fish and invertebrates
-Page 56 of 62-

Table 2. Summary of Submitted Terrestrial Toxicity Studies for Momfluorothrin. 

Exposure Scenario Species Exposure 

Duration

Toxicity Reference 

Value Effects

Reference / 

Study Classification / 

Formulation

Toxicity 

Category

Birds

Acute Oral Dose Bobwhite quail 

(Colinus 

virginianus)

14 day 

observation period

LD50 >2,250 mg a.i./kgbw

Mortality MRID 49019971

Acceptable

TGAI

Practically nontoxic

Acute Oral Dose

Zebra finch 

(Poephila guttata)

14 day 

observation period LD50 > 2,250 mg 

a.i./kg-bw

Mortality MRID 49019973

Supplemental

TGAI

Practically nontoxic

Acute Dietary Bobwhite quail (C.

virginianus)

5 day exposure, 3 

day post-exposure 

observation

LC50 >5,620 mg a.i./kg 

diet

Mortality MRID 49019975

Acceptable

TGAI

Practically nontoxic

Acute Dietary Mallard duck

(A. platyrhynchos)

5 day exposure, 3 

day post-exposure 

observation

LC50 >5,620 mg a.i./kg 

diet

Mortality MRID 49019977

Supplemental

TGAI

Practically nontoxic

Chronic Bobwhite quail (C.

virginianus)

20 weeks NOAEC < 241 mg 

a.i./kg diet

LOAEC = 241 mg 

a.i./kg diet

Adult female weight 

gain

MRID 49019979

Supplemental

TGAI

Not Applicable

Chronic Mallard duck

(A. platyrhynchos)

20 weeks NOAEC = 483 mg 

a.i./kg-diet

LOAEC = 992 mg 

a.i./kg-diet

Eggs laid MRID 49019981

Acceptable

TGAI

Not Applicable

Mammals

Acute Oral Dose Laboratory Rat

(Rattus norvegicus)

14 day 

observation period

LD50 > 2,000 mg a.i./kgbw

Mortality MRID 49020096

Acceptable

15.5% a.i.

Practically nontoxic
-Page 57 of 62-

Table 2. Summary of Submitted Terrestrial Toxicity Studies for Momfluorothrin. 

Exposure Scenario Species Exposure 

Duration

Toxicity Reference 

Value Effects

Reference / 

Study Classification / 

Formulation

Toxicity 

Category

Acute Inhalation Laboratory Rat

(R. norvegicus)

4 hours LC50 > 1.03 mg/L Mortality MRID 49020103

Acceptable

15.5% a.i.

Practically nontoxic

Chronic Laboratory Rat

(R. norvegicus)

90 days NOAEC = 200 mg 

a.i./kg diet

LOAEC = 500 mg 

a.i./kg diet

Decreased F1 and F2 

pup weight

MRID 49020018

Acceptable

TGAI

Not Applicable

Terrestrial invertebrates

Acute Honey bee

(Apis mellifera L.)

48 hours Contact LD50 = 0.2 μg 

a.i./bee

Mortality MRID 49019985

Acceptable

TGAI

Highly toxic

Oral LD50 = 5.08 μg 

a.i./bee

Mortality MRID 49019985

Acceptable

TGAI

Not Applicable

3 – 24 hours RT25 < 3 hours Mortality MRID 49020224

Supplemental

Formulated product 

(0.102% a.i.)

Not Applicable
-Page 58 of 62-

Table 2. Summary of Submitted Terrestrial Toxicity Studies for Momfluorothrin. 

Exposure Scenario Species Exposure 

Duration

Toxicity Reference 

Value Effects

Reference / 

Study Classification / 

Formulation

Toxicity 

Category

Sub Acute Earthworm (Eisenia 

fetida)

14 days LC50 = 97.6 mg a.i./kg 

soil dry weight

NOAEC = 15.6 mg 

a.i./kg soil dry weight

LOAEC = 31.3 mg 

a.i./kg soil dry weight

Body weight change MRID 49019983

Supplemental

TGAI

Not Applicable

Terrestrial Plants

Wheat (Triticum aestivum), Cucumber 

(Cucumis sativus), Cabbage (Brassica 

oleracea), and Tomato (Lycopersicon 

esculentum)

21 days Not Applicable Plant length, dry weight, 

necrotic area, 

germination

MRID 49020227

Supplemental

Formulated product 

(0.1% a.i.)

Toxicity categories 

are not specified for 

plants
-Page 59 of 62-

Appendix C. Model Outputs

SIP Model Outputs

Table 1. Inputs

Parameter Value

Chemical name momfluorothrin

Solubility (in water at 25oC; mg/L) 0.933

Mammalian LD50 (mg/kg-bw) 2000

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 10

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Avian LD50 (mg/kg-bw) 2250

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 483

Bobwhite quail NOAEC (mg/kg-diet) 241

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird 

species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.1605 0.1605

Adjusted toxicity value (mg/kg-bw) 1538.3211 7.6916

Ratio of exposure to toxicity 0.0001 0.0209

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals
-Page 60 of 62-

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.7557 0.7557

Adjusted toxicity value (mg/kg-bw) 1620.9664 23.9629

Ratio of exposure to acute toxicity 0.0005 0.0315

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. 

Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through 

drinking water may contribute to a total exposure that has potential for effects to non-target animals.

STIR Model Outputs

Input

Application and Chemical Information

Enter Chemical Name momfluorothrin

Enter Chemical Use aerosol spray

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) ground

Enter Chemical Molecular Weight (g/mole) 385.35

Enter Chemical Vapor Pressure (mmHg) 1.04E-08

Enter Application Rate (lb a.i./acre)

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2250

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 2000

Enter Lowest Rat Inhalation LC50 (mg/L) 1.03

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.16E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.71E-05

Adjusted Inhalation LD50 6.46E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.20E-06 Exposure not Likely Significant
-Page 61 of 62-

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 0.00E+00

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 0.00E+00 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.16E-04

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.41E-05

Adjusted Inhalation LD50 6.13E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 5.56E-07 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 0.00E+00

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 0.00E+00 Exposure not Likely Significant

T-REX Model Output for Mammalian Exposure

Upper Bound Kenaga Residues For RQ Calculation

Chemical Name: Momfluorothrin

 Use Aerosol Spray

 Formulation 0

Application Rate 0.9 lbs a.i./acre

Half-life 35 days 

Application Interval 0 days

Maximum # Apps./Year 1

Length of Simulation 1 year

Variable application rates? no

Dietary-based EECs (ppm) Kenaga

Values

Short Grass 216.00

Tall Grass 99.00

Broadleaf plants 121.50

Fruits/pods/seeds 13.50

Arthropods 84.60

Dose-based EECs 

(mg/kg-bw)

Avian Classes and Body Weights (grams)

small mid large

20 100 1000

Short Grass 246.00 140.28 62.81

Tall Grass 112.75 64.30 28.79

Broadleaf plants 138.38 78.91 35.33

Fruits/pods 15.38 8.77 3.93

Arthropods 96.35 54.94 24.60

Seeds 3.42 1.95 0.87
-Page 62 of 62-

Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients

Size Class

(grams)

Adjusted 

NOAEL

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 21.98 205.94 9.37 94.39 4.29 115.84 5.27 12.87 0.59 80.66 3.67 2.86 0.13

35 17.78 142.33 8.00 65.24 3.67 80.06 4.50 8.90 0.50 55.75 3.13 1.98 0.11

1000 7.69 33.00 4.29 15.13 1.97 18.56 2.41 2.06 0.27 12.93 1.68 0.46 0.06

T-REX Model output for avian exposure following dispersal of entire 7 oz can’s contents 

onto a 200 ft2 area.

Upper Bound Kenaga Residues For RQ Calculation

Chemical Name: Momfluorothrin

 Use 0

 Formulation 0

Application Rate 0.09 lbs a.i./acre

Half-life 35 days 

Application Interval 0 days

Maximum # Apps./Year 1

Length of Simulation 1 year

Variable application rates? no

Dietary-based EECs (ppm) Kenaga

Values

Short Grass 21.60

Tall Grass 9.90

Broadleaf plants 12.15

Fruits/pods/seeds 1.35

Arthropods 8.46