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Proposed Registration of the New Active Ingredient Momfluorothrin 

1 Executive Summary

The U.S. Environmental Protection Agency, hereafter referred to as EPA, is proposing to grant 

an unconditional registration under section 3(c)(5) of the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA) for the new active ingredient, momfluorothrin, formulated as four

manufacturing-use products and five end-use products. Momfluorothrin belongs to the synthetic 

pyrethroid class of chemicals and is a broad spectrum insecticide effective against flying, 

crawling, and stinging insects and other arthropod pests. The proposed uses for this new 

chemical include indoor and outdoor spot and crack-and-crevice treatments in residential and 

commercial settings, including application to indoor perimeters and mattresses to control bed 

bugs. The five end-use products are formulated, in combination with previously registered active 

ingredients, as ready-to-use aerosols.

The database submitted to support the assessment of human health risk is complete. The 

proposed uses are non-food uses and adequate exposure data are available to assess potential 

residential and occupational exposure. There are no risk estimates of concern for human health. 

Results from a screening-level ecological risk assessment indicate low potential for risks to nontarget organisms. While ecotoxicological uncertainties have been identified (e.g., avian 

reproduction toxicity, avian/passerine acute oral toxicity, benthic invertebrate chronic toxicity, 

estuarine/marine acute and chronic toxicity, aquatic nonvascular plant toxicity, terrestrial plant 

toxicity), the environmental fate and ecotoxicity databases are sufficient for assessing the risks 

associated with the proposed uses.

Momfluorothrin is considered practically non-toxic to birds and mammals. Although 

momfluorothrin is classified as highly toxic to fish, aquatic invertebrates, and terrestrial 

invertebrates, predicted exposures from ready-to-use aerosol formulations are based on label 

instructions that prohibit direct application to water. Furthermore, the use patterns involve 

spatially limited areas. To mitigate potential exposure to smaller water bodies in close proximity 

to treated areas, outdoor applications are limited to spot and crack-and-crevice treatments, and 

product labels prohibit application within 25 feet of water. To reduce risk to insect pollinators, 

application is prohibited if bees are foraging in treatment areas. 

Momfluorothrin is efficacious against several pests of public health concern, including flies, 

mosquitoes, wasps, hornets, yellow jackets, roaches, ticks, bed bugs, scorpions, centipedes, and 

certain species of ants and spiders. Additionally, momfluorothrin has a lower ecological hazard

profile relative to alternative registered products across several taxa.
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2 Requested Action

On January 10, 2013, EPA received an application to register products containing the new active 

ingredient, momfluorothrin, an insecticide for non-food indoor and outdoor residential and 

commercial use. 

Proposed Use Pattern: Indoor and outdoor spot and crack-and-crevice treatments in residential 

and commercial settings, including application to indoor perimeters and mattresses.

Target Pests: Flying, crawling, and stinging insects and other arthropod pests, including: flies, 

mosquitoes, wasps, hornets, yellow jackets, roaches, ticks, bed bugs, centipedes, scorpions, and 

certain species of ants and spiders.

Applicants: I2L Research USA Inc., 1330 Dillon Heights Ave., Baltimore, MD 21228–1199, on 

behalf of Sumitomo Chemical Company, LTD., 27–1, Shinkawa 2-Chome, Chuo-Ku, Tokyo 

104–8260, Japan; and McLaughlin Gormley King Co., 8810 Tenth Ave North, Minneapolis, MN 

55427-4319.

3 Chemical Information

Chemical Name: Momfluorothrin, 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-

(1RS,3RS;1RS,3SR)-3-(2-cyanoprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate

EPA PC Code: 016331

Chemical Abstracts Service (CAS) Number: 609346-29-4

IRAC Mode of Action Classification: Group 3A, Sodium Channel Modulator

Mode of Action: Axonic poison; keeps sodium channels in the neuronal membranes open, 

leading to hyperexcitation and paralysis.

4 Human Health Risk Assessment

Provided below is a summary of the human health effects and risk of momfluorothrin, as 

assessed in the document entitled, “Momfluorothrin. Human Health Risk Assessment for a 

Proposed Use of the New Active Ingredient in Indoor Residential Settings and Outdoors in 

Commercial/Residential Settings.” The database is complete and the assessment resulted in no 

risk estimates of concern.

4.1 Hazard Characterization

Momfluorothrin has been evaluated for a variety of toxic effects in experimental toxicity studies. 

Neurotoxic effects (i.e., tremors) consistent with Type I pyrethroids were observed following 

oral gavage. No neurotoxic effects were observed throughout the database following dietary or 
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dermal exposure. This is consistent with other pyrethroids, which are metabolized and excreted 

from the system relatively quickly following dietary exposure, in contrast to bolus/gavage 

dosing, which results in greater maximal plasma concentrations immediately following exposure. 

Thus, an internal dose sufficient to disrupt the sodium channels is unlikely to be achieved via 

dietary exposure. Following dietary administration, however, decreased body weight and liver 

toxicity in rats, mice, and dogs were observed, leading to tumor formation in male rats at highdoses following chronic exposure. In addition, liver toxicity was also observed following 28-day 

inhalation exposure to rats. No treatment-related neurotoxic effects were observed following 

inhalation exposure. 

No increased pre- or post-natal susceptibility was observed following developmental toxicity 

studies in rats and rabbits. No signs of neurotoxicity were observed following post-natal 

exposure to pups in a 2-generation reproductive toxicity study. Increased time to sexual 

maturation was observed in both high-dose male and female rats in the 2-generation reproductive 

toxicity study. The slight increases in sexual male maturation times were considered within 

normal biological variation (~1.3 days) and are consistent with significantly decreased body 

weights. However, increased sexual maturation in females is considered treatment-related as the 

effect was more pronounced (~3 days) and occurred in the absence of significant body-weight 

decreases. This effect occurred in the presence of maternal toxicity including significantly 

decreased body weights and increased hepatocellular hypertrophy, and at a dose approximately 

4-fold higher than the point of departure (POD) selected for risk assessment. 

Momfluorothrin did not result in any systemic toxicity following dermal exposure for 28 days up 

to the limit dose. Low systemic toxicity via the dermal route is most likely due to the low 

potential for dermal absorption through the skin. A dermal penetration study for momfluorothrin 

is available, and based on the available data a dermal-absorption factor of 3.5% was considered 

appropriate for risk assessment. This is consistent with results from other pyrethroids which in 

general have a low dermal-absorption value of 5% or less. 

No evidence of immunotoxicity or genotoxicity was identified in the database. Momfluorothrin 

is classified as “not likely to be carcinogenic to humans at doses that do not result in a mitogenic 

response.” This classification is based on an increased incidence of liver adenomas and 

carcinomas in both sexes of Wistar rat, as well as supporting mechanistic studies demonstrating a 

mitogenic mode of action based on induction of liver cytochrome p450, resulting in a 

proliferative (mitogenic) response and eventual tumor formation. Genotoxicity studies were 

negative. A linear quantification of cancer risk was not required and the doses selected for risk 

assessment are protective of potential carcinogenic effects.

4.1.1 Safety Factor

The Agency will apply a 3X safety factor based on pharmacokinetic considerations for infants 

and children <6 years old. The 3X is based on an approximation of increased deltamethrin (the 

index chemical for pyrethroids) concentrations predicted in juvenile rats (10- and 21-days old)

compared to 90-day old adult rats. The 3X is considered to be sufficiently protective because 1) 

increased juvenile sensitivity is not expected at low environmental concentrations; 2) agedependent physiologically-based pharmacokinetic models predict a 3-fold increase in juvenile 

brain tissue compared to adults; and 3) the pharmacokinetics of pyrethroids as a group are
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sufficiently similar that significant deviations from the predicted 3-fold increase in 

concentrations are not expected. 

Furthermore, the toxicology database for momfluorothrin is complete. There are no residual 

uncertainties with regard to assessment of pre- and post-natal susceptibility. Acceptable 

developmental toxicity studies in rats and rabbits and an acceptable 2-generation reproduction 

study in rats are available for momfluorothrin. 

In the developmental toxicity study, tremors were observed in dams. However, no effects were 

observed on the developing fetus. A slight delay in female sexual maturation and decreased pup 

body weights were observed in the 2-generation study; however, this effect only occurred in the 

high-dose group and in the presence of significant maternal toxicity. The degree of concern for 

these effects in infants is low because the rat reproductive and offspring effects have clearly 

defined no observed- and lowest observed- adverse effects levels (NOAELs and LOAELs), and 

the POD selected for risk assessment is protective of these effects. No neurotoxic effects were 

observed in pups or dams in the 2-generation reproductive toxicity study.

After reviewing the extensive body of peer-reviewed literature on pyrethroids, the Agency has no 

residual uncertainties regarding age-related sensitivity for women of child-bearing age as well as 

for all adult populations and children >6 years of age, based on the absence of pre-natal 

sensitivity observed in 76 guideline studies for 24 pyrethroids and the scientific literature. 

Additionally, no evidence of increased quantitative or qualitative susceptibility was seen in the 

pyrethroid scientific literature related to pharmacodynamics. 

Finally, there are no residual uncertainties in the exposure database. The proposed uses are nonfood uses, and adequate data are available to assess potential occupational and residential 

exposures. 

4.1.2 Cumulative Effects

Pyrethroids and pyrethrins share a common mechanism of toxicity; chemicals in this group 

interact similarly with voltage-gated sodium channels, ultimately leading to neurotoxicity. A 

cumulative risk assessment (CRA) for pyrethroids/pyrethrins was completed in 2011. No 

cumulative risks of concern were identified. Further information regarding EPA’s efforts to 

evaluate the risk of exposure to pyrethroids and pyrethrins is available at: 

http://www.epa.gov/oppsrrd1/reevaluation/pyrethroids-pyrethrins.html.

EPA has determined that, based on its chemical structure and the observation of neurobehavioral 

effects consistent with Type I pyrethroids, momfluorothrin should be included in the common 

mechanism grouping for pyrethroids and pyrethrins. Thus, as part of the assessment for the 

proposed uses of momfluorothrin, EPA performed a quantitative exposure and risk assessment to 

determine if these uses will significantly contribute to or change the overall findings of the 2011 

pyrethroids/pyrethrins CRA. 

The assessment utilized the momfluorothrin relative potency factor of 0.19 (as compared to 

deltamethrin, the index chemical for the pyrethroids), as well as the same exposure algorithms 

and inputs that were used in the CRA. Adult indoor exposures and cumulative risks are currently 
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driven by the cypermethrin indoor use pattern with a margin of exposure (MOE) of 3,900, which 

is lower than the momfluorothrin MOE of 81,000. The cypermethrin indoor use pattern also

drives the CRA for children’s indoor exposure and risk, with a combined (dermal and incidental 

oral) MOE of 720, which is lower than the momfluorothrin MOE of 15,000. Thus, the risk 

estimates for momfluorothrin do not exceed those previously considered in the

pyrethroids/pyrethrins CRA.

Based on these findings, EPA has determined that the proposed uses of the new active

ingredient, momfluorothrin will not contribute significantly to or change the overall findings of

the 2011 pyrethroids/pyrethrins cumulative risk assessment. 

4.1.3 Toxicological Endpoints 

Route-specific toxicity studies were selected for assessment of short-term incidental oral and 

short- and intermediate-term inhalation exposures (See Table 1). A dermal POD was not chosen 

because systemic toxicity was not seen in a 28-day dermal toxicity study in rats up to the limit 

dose. As toxicological effects through the inhalation and oral routes of exposure are different, 

these exposure routes were not combined in the assessment.

Table 1. Summary of Toxicological Doses and Endpoints for Momfluorothrin for Use in 

Human Health Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty/

Safety Factors

RfD/PAD, Level 

of Concern

Study and Toxicological 

Effects

Incidental Oral

Short-Term

(1-30 days)

NOAEL = 25 

mg/kg/day

UFA = 10x

UFH = 10x

SF = 3X

Residential LOC 

for individuals < 6 

years old = 300

Developmental Toxicity Study 

(rat). MRID: 49020016.

LOAEL = 75 mg/kg/day based 

on tremors observed in dams at 

the high-dose.

Dermal

Short-Term

(1-30 days) and 

Intermediate-Term

(1-6 months)

In a 28-day dermal toxicity study in rats, no dermal toxicity was observed up to the limit 

dose (1,000 mg/kg/day). No evidence of increased susceptibility was observed, and low 

dermal absorption value was reported. Therefore, no dermal assessment is 

recommended.

Inhalation

Short-Term

(1-30 days) and 

Intermediate-Term

(1-6 months)

NOAEL = 

0.150 mg/L

UFA = 3x

UFH = 10x

LOC for MOE = 

30

28-Day Inhalation toxicity 

(rat). MRID: 49020012

LOAEL = 0.300 mg/L based 

on increased liver weights, 

AST, and cholesterol.

Cancer (oral)

Classification: Not likely to be carcinogenic to humans at doses that do not result in a 

mitogenic response, based on negative genotoxicity data and mechanistic data 

supporting a non-linear mode of action (induction of cytochrome p450 with proliferative 

response) for liver tumors in male and female rats. Doses selected for risk assessment 

are protective of carcinogenicity.

Point of Departure (POD) = A data point or an estimated point derived from observed dose-response data and used to mark the beginning of 

extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. 

LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation from animals to humans (interspecies). UFH = 

potential variation in sensitivity among members of the human population (intraspecies). SF = Safety Factor. cPAD = chronic population adjusted 

dose. RfD = reference dose. N/A = not applicable. HEC = human equivalent concentration. HED = human equivalent dose.
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For the incidental oral assessments, EPA is establishing an overall LOC of 300. This LOC is 

based on standard inter- and intra-species uncertainty factors of 10X, and an additional 3X safety 

factor based on pharmacokinetic considerations for infants and children <6 years old.

For inhalation assessments, EPA is establishing an overall LOC of 30. The standard interspecies 

extrapolation uncertainty factor can be reduced from 10X to 3X based on a human equivalent 

concentration calculation accounting for pharmacokinetic interspecies differences. The 

intraspecies uncertainty factor remains at 10X.

4.2 Exposure and Risk Characterization

4.2.1 Dietary Exposure and Risk

Based on the proposed uses, exposure to momfluorothrin through food or drinking water is not 

expected; thus, a dietary risk assessment is not required.

4.2.2 Residential Exposure and Risk

Based on the proposed uses of momfluorothrin, EPA has determined that there is potential for 

exposure in residential settings. In assessing residential exposure and risk, EPA considered 

exposure to residential handlers (i.e., adult individuals involved in the pesticide application 

process), as well as potential post-application exposure to residues for young children. 

4.2.2.1 Residential Handler Exposure and Risk: 

The proposed uses of momfluorothrin in indoor and outdoor residential settings may result in 

adult residential handler exposure. This type of exposure is expected to be only short-term in 

duration (i.e., 1 to 30 days), as intermediate- or long-term exposures are not likely based on the 

intermittent nature of applications by homeowners. Since no dermal hazard was identified for 

momfluorothrin in the toxicological database, only inhalation exposure was assessed. The 

resulting MOE of 440,000 is not of concern, as EPA’s LOC for this route of exposure is an MOE 

of less than 30.

4.2.2.2 Residential Post-Application Exposure and Risk

The proposed uses of momfluorothrin in indoor residential settings may also result in postapplication exposure, which is expected to be only short-term in duration (i.e., 1 to 30 days). 

Incidental oral (hand-to-mouth and object-to-mouth) exposures to residues deposited from indoor 

spot, crack-and-crevice, and bed bug treatments were assessed for children 1 to <2 and 3 to <6 

years of age. The resulting MOEs for all scenarios, ranging from 8,300 to 240,000, are not of 

concern, as EPA’s level of concern (LOC) is an MOE of less than 300. 

4.2.3 Aggregate Exposure and Risk

Based on the proposed uses, exposure to momfluorothrin through food or drinking water is not 

expected; thus, a quantitative aggregate risk assessment is not required at this time.
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4.2.4 Occupational Exposure and Risk

In assessing occupational exposure and risk, EPA assessed exposure to occupational handlers 

(i.e., adult individuals involved in professional pesticide applications). In consideration of the use 

patterns and baseline personal protective equipment used by professional applicators, exposures 

are expected to be less than those quantitatively presented for residential scenarios, and no risks 

are expected.

4.2.4.1 Occupational Handler Exposure and Risk

Occupational handler exposure is expected to be short- or intermediate-term in duration (i.e., 1 to 

30 days, or 1 to 6 months). Since no dermal hazard was identified for momfluorothrin in the 

toxicological database, only inhalation exposure was assessed. The resulting MOE of 4,900,000 

is not of concern, as EPA’s level of concern (LOC) is an MOE of less than 30. 

4.2.4.2 Occupational Post-Application Exposure and Risk

Although a specific re-entry interval is not required on the product labels, post-application 

exposure is not expected, and no risks of concern are expected from this scenario. Furthermore, 

no dermal hazard has been identified for momfluorothrin in the toxicological database. 

5 Ecological Risk Assessment

Provided below is a summary of the environmental fate and ecological risks of momfluorothrin, 

as assessed in the document entitled, “Environmental Fate and Ecological Risk Assessment for 

the Section 3 New Chemical Registration of the Pyrethroid Insecticide Momfluorothrin.” 

Results from a screening-level ecological risk assessment indicate low potential for risks to nontarget organisms. While ecotoxicological uncertainties have been identified (e.g., avian 

reproduction toxicity, avian/passerine acute oral toxicity, benthic invertebrate chronic toxicity, 

estuarine/marine animal acute and chronic toxicity, aquatic nonvascular plant toxicity, terrestrial 

plant toxicity), the environmental fate and ecotoxicity databases are sufficient for assessing the 

risks associated with the proposed uses.

Momfluorothrin is considered practically non-toxic to birds and mammals. Although 

momfluorothrin is classified as highly toxic to fish, aquatic invertebrates, and terrestrial 

invertebrates, predicted exposures from ready-to-use aerosol formulations are expected to be 

spatially restricted to small areas. To mitigate potential exposure to smaller water bodies in close 

proximity to treated areas, outdoor applications are limited to spot and crack-and-crevice 

treatments, and product labels prohibit application within 25 feet of water. To reduce risk to 

insect pollinators, application is prohibited if bees are foraging in treatment areas.

5.1 Environmental Fate 

Momfluorothrin degrades through a combination of biotic and abiotic reactions, and is slightly 

persistent in the environment. Under acidic and neutral conditions, momfluorothrin is relatively 
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stable to hydrolysis, but it undergoes hydrolysis at a pH of 9, with half-lives ranging from 7 to 12 

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

biodegrades in aerobic soils with half-lives of <5 days, and under aerobic aquatic systems with 

half-lives of <3 days.

Momfluorothrin is considered slightly mobile in soils and its potential to leach into groundwater 

is low. If released to water, momfluorothrin will rapidly partition to the sediment compartment. 

In an acceptable aquatic metabolism study, momfluorothrin degraded rapidly with a reported 

half-life < 3 days. Momfluorothrin has a log octanol-water partition coefficient (log Kow) of <3, 

and thus has low potential to accumulate in aquatic organisms such as fish.

5.2 Ecological Exposure

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

typically based on aquatic and terrestrial models that calculate estimated environmental 

concentrations (EECs) 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, the exposure assessment for momfluorothrin is qualitative 

in nature.

5.2.1 Exposure to Aquatic Life

It is possible for aquatic organisms to be exposed to momfluorothrin via surface water 

contamination from pesticide drift and runoff. However, momfluorothrin is not expected to 

bioaccumulate in aquatic organisms. Furthermore, based on the proposed outdoor use patterns 

(i.e., spot and crack-and-crevice treatments) and proposed label prohibitions against application 

to or near water bodies, EPA believes that the potential for momfluorothrin to reach aquatic 

habitats and result in exposure to non-target organisms is low.

5.2.2 Exposure to Terrestrial Wildlife, Plants, and Beneficial Invertebrates

It is possible that mammals and birds (surrogates for terrestrial-phase amphibians and reptiles) 

may be exposed to momfluorothrin via consumption of treated items contaminated by direct 

spray or spray drift as a result of application. Plants and non-target invertebrates may also be 

exposed to momfluorothrin via pesticide drift and runoff. However, based on the proposed 

outdoor use patterns (i.e., spot and crack-and-crevice treatments) and proposed label language to 

reduce inadvertent drift and runoff, EPA believes that the potential for momfluorothrin to result 

in exposure to non-target terrestrial organisms is low.

5.3 Ecological Effects

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 toxicity data for birds, mammals, fish, aquatic and terrestrial invertebrates, and aquatic and 

terrestrial plants for technical grade momfluorothrin, as well as for a typical formulated end-use 

product (e.g., momfluorothrin co-formulated with phenothrin). Birds are used as surrogates for 
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reptiles and terrestrial-phase amphibians and freshwater fish are used as surrogates for aquaticphase amphibians. 

5.3.1 Aquatic Organisms

5.3.1.1 Freshwater Fish

Momfluorothrin is classified as very highly toxic to freshwater fish. The acute toxicity of 

technical grade momfluorothrin was evaluated in several species, with 96-hour LC50 values 

ranging from 1.2 μg a.i./L in rainbow trout to 7.6 μg a.i./L in fathead minnow. A study assessing 

the acute toxicity of a formulation containing 0.12% momfluorothrin and 0.25% phenothrin in 

rainbow trout yielded 96-hour LC50 values of 1.3 μg momfluorothrin/L and 6.6 μg phenothrin/L, 

indicating that the acute toxicity of momfluorothrin to rainbow trout is not enhanced in mixtures 

compared to momfluorothrin alone.

A 32-day chronic toxicity study in fathead minnow showed no significant effects to embryo 

hatching success, the number of live normal larvae at hatch (i.e., larval survival), post hatch 

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

NOAEC survival value of 3.1 μg a.i./L. 

5.3.1.2 Freshwater Invertebrates

Momfluorothrin is classified as very highly toxic to freshwater invertebrates. The acute toxicity 

of momfluorothrin was evaluated in daphnia, with a 48-hour EC50 of 7.8 μg a.i./L. A 48-hour 

daphnia test with a formulation containing 0.12% momfluorothrin and 0.25% phenothrin yielded 

an EC50 of 16.5 μg a.i./L for momfluorothrin, indicating that the toxicity of momfluorothrin in 

mixtures is similar to momfluorothrin alone. 

Two momfluorothrin chronic toxicity studies were submitted for freshwater invertebrates; a 21-

day daphnia lifecycle toxicity study, and a 49-day midge lifecycle test in a water-sediment 

system. 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, (LOAEC = 9.3 

μg a.i./L, NOAEC = 3.1 μg a.i./L) in the chronic daphnia study. The sediment toxicity test with 

midge determined statistically significant effects to male development rate and combined malefemale 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. As a definitive NOAEC value was not determined from the 

chronic midge study, there is uncertainty surrounding the momfluorothrin toxicity threshold for 

this taxon. 

5.3.1.3 Estuarine/Marine Fish and Invertebrates

Acute and chronic estuarine/marine fish or estuarine/marine invertebrate toxicity studies were 

waived for momfluorothrin. Based on the proposed outdoor use patterns (i.e., spot and crackand-crevice treatments) and proposed label prohibitions against application to or near water 

bodies, EPA believes that the potential for momfluorothrin to reach estuarine/marine habitats is 

low.
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5.3.1.4 Aquatic Plants

The 7-day toxicity of momfluorothrin to aquatic vascular plants was evaluated for Lemna gibba, 

with an IC50 greater than 2,500 μg a.i./L. The 96-hour toxicity of momfluorothrin to aquatic nonvascular plants was evaluated for Pseudokirchneriella subcapitata, although an EC50 could not 

be reliably determined because of potential interference from the co-solvent. Based on the 

proposed outdoor use patterns (i.e., spot and crack-and-crevice treatments) and proposed label 

prohibitions against application to or near water bodies, EPA believes that the potential for 

momfluorothrin to reach aquatic habitats is low.

5.3.2 Terrestrial Wildlife, Plants and Beneficial Invertebrates

5.3.2.1 Mammals

Mammalian toxicity data conducted on laboratory rats were used to approximate toxicity to wild 

mammals. Based on the reported oral LD50 value of >2,000 mg/kg-bw for a 15.5% 

momfluorothrin formulation, momfluorothrin is considered practically non-toxic to small 

mammals. Acute dermal testing with rats also yielded an LD50 >2,000 mg/kg-bw. An acute 

inhalation toxicity study, while producing no mortalities, found clinical signs in female rats 

exposed to 1.03 mg/L, including tremors, tremors of tail, ataxic gait or urinary incontinence.

5.3.2.2 Birds

The results of acute oral and dietary toxicity testing for momfluorothrin indicate that it is 

practically non-toxic to avian species, including passerine species. In acute oral toxicity studies, 

the LD50 value for bobwhite quail (Colinus virginianus) was >2250 mg a.i./kg-bw, and no 

clinical signs of toxicity were observed at any treatment level. Avian acute oral toxicity testing 

with zebra finch (Poephila guttata) did not yield a NOAEC due to regurgitation at the lowest 

dose tested. Even if the birds that regurgitated the dose were counted as mortalities, however, the 

LD50 would still be greater than 2,250 mg/kg-bw, the highest dose tested. In sub-acute dietary 

toxicity studies, the LC50 for momfluorothrin was >5,620 mg a.i./kg-diet for mallard duck (Anas 

platyrhynchos) and bobwhite quail.

5.3.2.3 Terrestrial Invertebrates

Momfluorothrin is classified as highly toxic to honey bees (Apis mellifera), based on an acute 

contact LD50 value of 0.20 μg a.i./bee and an oral LD50 value or 5.08 μg a.i./bee. A honey bee 

foliar residue toxicity study for alfalfa treated with 0.1% momfluorothrin and 0.2% phenothrin 

yielded an RT25 (residual time to 25% mortality) of less than three hours.

In a sub-acute earthworm toxicity test, 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.

5.3.2.4 Terrestrial Plants

The toxicity of momfluorothrin to seedling emergence and vegetative vigor in terrestrial plants 

was evaluated for monocots and in a dual-concentration limit test. Observations of phytotoxic 
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response (percentage of necrotic area, effects on plant length, dry weight and germination) 

following exposure to a formulation containing 0.1% momfluorothrin and 0.2% phenothrin at 

rates of 500 g/10 m2 were limited to monocot necrosis, whereas exposure at rates of 5000 g/10 

m2resulted in observed phytotoxic response encompassing reduced germination, necrotic area, 

and height. Due to the observed toxicity at one of the limit doses tested, 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, there is uncertainty regarding the toxicity of momfluorothrin to terrestrial plants. 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.

5.4 Ecological Risk

In its qualitative assessment, EPA identified risks of concern by estimating the amount of active 

ingredient (i.e., number of cans of formulated product) that would need to reach a water body to 

result in risk to non-target organisms, and considering the likelihood of such hypothetical 

exposures occurring, based on the proposed use patterns and labeling. Comparisons of toxicity to 

exposure are included as part of the risk description. 

5.4.1 Aquatic Organisms

EPA evaluated risk to aquatic systems by dividing systems into two general compartments: the 

water column (the aquatic area between surface and the benthos), and the benthos (sediments and 

an area extending approximately 6 inches above the sediment). Aquatic risk predictions for fish 

and aquatic invertebrates are low due to the nature of the proposed uses and aerosol form.

Adverse effects to aquatic plants are not expected.

5.4.1.1 Water Column

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

amphibians) and aquatic invertebrates on an acute exposure basis. Assuming a standard farm 

pond of 20 million liters, acute listed species LOCs would be exceeded for freshwater fish and 

freshwater invertebrates following release of approximately 2 and 15 aerosol cans of product, 

respectively. This particular exposure scenario would qualify as product misuse, as direct 

application to or near water is prohibited, and is thus unlikely to be realized in the environment.

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

affected in the toxicity studies, but the exposure concentrations that would result in RQs 

exceeding the chronic LOCs for freshwater fish and invertebrates are very high; it would take 

between 20-100 cans in the standard farm pond to reach that threshold. 

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

the proposed use patterns and anticipated dilution of the product prior to it reaching 

estuarine/marine habitat areas, risk to estuarine/marine organisms is expected to be low. 
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5.4.1.2 Benthos (Sediment)

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 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. While populations of benthic aquatic invertebrates may be 

adversely affected by drift or runoff, EPA expects the extent of these impacts to be reduced by 

the spatially-limited nature of the proposed application use patterns, and the low amount of 

momfluorothrin in the proposed products. 

5.4.1.3 Aquatic Plants

It would take over 300 cans being applied/released directly into the modeled pond before EECs 

would exceed the listed species LOC for aquatic vascular and nonvascular plants. Thus, potential 

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

5.4.2 Terrestrial Organisms

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, exposure is expected to be spatially and temporally limited. Thus, direct 

adverse effects to terrestrial invertebrates are not expected.

5.4.2.1 Mammals

Acute risk to mammals is considered to be low. 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 momfluorothrintreated food items from spray drift or large quantities of dispersed product is unlikely.

Chronic risk to mammals is also considered to be low. A chronic mammalian dietary study 

determined a NOAEL of 200 mg a.i./kg-diet. In order to exceed chronic LOC of 1 on a dietaryor dose-basis, the application rate would have to be greater than 0.8 lbs a.i./acre. An entire 7 

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

over a 200 square foot area, 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 risk 

quotients (RQs) to exceed the chronic LOC. 

5.4.2.2 Birds

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 momfluorothrin-residues 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. 
Page 14 of 21

 

Chronic risk to avian species is also expected to be low. Chronic avian reproduction testing with 

northern bobwhite quail found effects at all concentrations tested. Since a NOAEC 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 estimates for short grass would 

be approximately 21 ppm for a scenario involving uniform distribution of an entire can’s 

contents over a 200 square foot area, 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. Furthermore, pyrethroids as a class are not known to have chronic avian toxicity 

concerns. 

5.4.2.3 Terrestrial Invertebrates

While available toxicity data indicate that adverse effects to individual non-target insects are 

likely to result from exposure, exposure is expected to be spatially and temporally limited. Thus,

acute and chronic risk to non-target terrestrial invertebrates is considered unlikely.

5.4.2.4 Terrestrial Plants

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 aerosol 

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 the Agency’s risk assessment; however, additional 

terrestrial plant toxicity testing would be needed to assess the risk to plants from any future 

broadcast use of momfluorothrin.

6 Benefits and Alternatives

Momfluorothrin is efficacious against several pests of public health concern, including flies, 

mosquitoes, wasps, hornets, yellow jackets, roaches, ticks, bed bugs, scorpions, centipedes, and 

certain species of ants and spiders. The end-use products are classified as acute toxicity category 

III and IV for all routes of exposure and bear the “Caution” signal word.

Consistent with its mode of action, momfluorothrin is toxic to fish, aquatic invertebrates, and 

terrestrial invertebrates. However, across these taxa momfluorothrin has a comparable—or in 

some cases, lower—ecological hazard profile relative to alternative registered products with 

similar use patterns, including other synthetic pyrethroids (bifenthrin, permethrin, tetramethrin), 

pyrethrins, and the neonicotinoid imidacloprid (See Table 2).

Compared to bifenthrin and permethrin, momfluorothrin is less toxic to fish, aquatic 

invertebrates, and terrestrial vertebrates. Compared to pyrethrins, it is less toxic to aquatic and 

terrestrial invertebrates. Although momfluorothrin is more toxic to fish than imidacloprid, 

exposure to fish, as discussed above, is expected to be low based on the labeled use patterns and 
Page 15 of 21

prohibitions against application near bodies of water. Toxicity to fish and terrestrial invertebrates 

is comparable with tetramethrin.

Table 2. Ecological Hazard Comparison of Momfluorothrin Alternatives

Momfluorothrin Bifenthrin Imidacloprid Permethrin Pyrethrin Tetramethrin

Acute Fish 1.2 μg a.i./L 0.15 μg 

a.i./L

> 83,000 

μg/L

0.79 μg 

a.i./L

5.1 μg 

a.i./L 3.7 μg a.i./L

Chronic 

Fish 3.1 μg a.i./L 0.04 μg a.i./L 1,200 μg/L 0.0515 μg a.i./L

1.9 μg 

a.i./L No data

Acute 

aquatic 

invertebrates

7.8 μg a.i./L 0.004 μg 

a.i./L 37 μg/L 0.018 μg a.i./L

0.14 μg 

a.i./L No data

Chronic 

aquatic 

invertebrates

1.8 μg a.i./L 

pore water

0.0013 μg 

a.i./L 0.6 μg/L 0.011 μg a.i./L

0.86 μg 

a.i./L No data

Terrestrial 

invertebrates

Contact LD50 = 

0.2 μg a.i./bee 0.015 μg/bee 0.078 μg/bee (contact)

0.024 μg 

a.i./bee 

(contact)

0.022 μg 

a.i./bee 

(contact)

0.155 μg/bee 

(contact)

 Note: No toxicity data available for terrestrial plant hazard comparison

Considerably less toxic 

compared to momfluorothrin

Toxicity comparable to 

momfluorothrin

Considerably more toxic than

momfluorothrin

7 Proposed Regulatory Decision

Under Section 3(c)(5) of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the 

Agency is proposing to unconditionally register pesticide products containing the new active 

ingredient momfluorothrin for use in indoor and outdoor residential and commercial settings. 

The products under consideration for the new uses are summarized below.

10308-GL (SUMIFREEZETM Manufacturing Use Product)

 15.7% momfluorothrin

 MUP, for formulation into direct spray products for indoor non-food and outdoor residential 

use

10308-GA (S-1563 Flying and Crawling Insect Killer Spray)

 0.1% momfluorothrin, 0.2% d-phenothrin

 Indoor and outdoor spot and crack and crevice applications

 Pests include: flies, mosquitoes, wasps, hornets, yellow jackets, ants, roaches, spiders

1021-EANR (MGK 2981)

 7% momfluorothrin, 14% cypermethrin

 MUP, for formulation into insecticide products for indoor and outdoor residential use
Page 16 of 21

1021-EANE (MGK 2983)

 2.225% momfluorothrin, 17.800% PBO

 MUP, for formulation into products for indoor and outdoor residential use 

1021-EANG (MGK 2987)

 5% momfluorothrin, 20% d-phenothrin

 MUP, for formulation into direct spray products

1021-EANU (MGK 29811)

 0.025% momfluorothrin, 0.05% cypermethrin

 Indoor residential use, spot, crack and crevice, bedframes, mattress and furniture tufts and 

seams, livestock housing (non-food)

 Pests include: ants, Asian lady beetles, bed bugs, spiders, boxelder bugs, ticks, carpet beetles, 

American cockroaches, crickets, fleas, scorpions, silverfish, sowbugs

1021-EANL (MGK 29831)

 0.05% momfluorothrin, 0.4% PBO

 Indoor and outdoor spot and crack and crevice applications

 Pests include: flies, mosquitoes, moths

1021-EANA (MGK 29871)

 0.05% momfluorothrin, 0.2% d-phenothrin

 Indoor and outdoor spot and crack and crevice applications

 Pests include: wasps, hornets, yellow jackets, scorpions

1021-EANT (MGK 29872)

 0.05% momfluorothrin, 0.2% d-phenothrin

 Indoor and outdoor spot and crack and crevice applications

 Pests include: wasps, hornets, yellow jackets, scorpions

7.1 Public Comments

On October 30, 2013, EPA published in the Federal Register a Notice of Receipt of an 

application to register momfluorothrin, and announced a public comment period of 30 days. Two 

comments were received: one from the San Francisco Bay Regional Water Quality Control 

Board (SFB RWQCB); one from the California Stormwater Quality Association (CASQA). The 

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. EPA appreciates the comments provided by SFB RWQCB and CASQA regarding the 

proposed registration of momfluorothrin. Excerpts from the submitted comments and EPA’s 

responses are provided below.
Page 17 of 21

SFB RWQCB and CASQA:

...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 sediments 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 nontoxic. If momfluorothrin use consistent with the label instructions can result in toxicity in the 

receiving water, further restrictions on use (such as modified label instructions or limitations 

on the types of retail products sold) must be evaluated. We encourage EPA to pay special

attention to application types–like control of insects around buildings and pre-construction 

termiticide applications–that are being addressed in EPA’s pyrethroid registration reviews...

EPA Response: 

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

especially in urban areas, as a result 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 publicly owned treatment works (POTW) effluent and biosolids issues are not 

believed to be of concern. 

In the event that momfluorothrin is transported to a waterway, its relatively 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. 
Page 18 of 21

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, EPA believes that available monitoring data for pyrethroids do offer 

some potential to evaluate cumulative ecological risk in a retrospective manner. The Agency 

may 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.

SFB RWQCB:

Develop endocrine disrupting analyses—Assess potential endocrine disruption effects in aquatic 

and amphibian species through lifecycle fish studies prior to registration. 

EPA Response:

The Agency is working towards integrating the EDSP and the Registration Review program 

by aligning the business processes involved with the programs so that the Agency no longer 

uses a fixed list approach for pesticide active ingredients. Pesticide chemicals that are new 

registrations will be addressed when those chemicals are due for re-evaluation under the 

Registration Review program. This process alignment will achieve simultaneous EDSP and 

Registration Review decisions, greatly enhancing efficiency for both the Agency and 

pesticide registrants. 
Page 19 of 21

This being said, the Agency undertakes a comprehensive review of each new registration 

and, in reaching its decisions regarding registration eligibility, considers a wide range of 

toxicity studies that provide information on endocrine-related effects, including: the rat 2-

generation reproduction study (or the Extended 1-generation reproduction study), 

mammalian subchronic bioassays (in rats and dogs), mammalian chronic bioassays (in rats 

and dogs), cancer bioassays (in rats and mice), mammalian prenatal developmental studies 

(usually in rats and rabbits), the developmental neurotoxicity study (in rats), fish 

development and reproduction studies (usually in fathead minnow and rainbow trout), avian 

reproduction studies (usually in bobwhite quail and mallard duck), and an estuarine/marine 

invertebrate life cycle study (usually in daphnid or mysid shrimp). The Agency will continue 

to use the best available science, as it evolves (such as through the work on EDSP21), to 

assess the potential risks posed by pesticides and will modify its assessment methodologies, 

as appropriate. For more information about the EDSP, please visit our website at 

www.epa.gov/endo.

7.2 Regulatory Rationale

There are no human health risks of concern from the proposed uses of momfluorothrin in indoor 

and outdoor residential and commercial settings. Estimates of both residential and occupational 

handler and post-application risk are well below EPA’s level of concern. Furthermore, as the 

proposed uses are non-food uses, limited in scope, there will be no exposure to momfluorothrin 

through food or drinking water.

Results from a screening-level ecological risk assessment indicate low potential for risks to nontarget organisms. Momfluorothrin is considered practically non-toxic to birds and mammals. 

Although momfluorothrin is classified as highly toxic to fish, aquatic invertebrates, and 

terrestrial invertebrates, predicted exposures from ready-to-use aerosol formulations are expected 

to be spatially restricted to small areas. To mitigate potential exposure to smaller water bodies in 

close proximity to treated areas, outdoor applications are limited to spot and crack-and-crevice 

treatments, and product labels prohibit application within 25 feet of water. To reduce risk to 

pollinators, application is prohibited if bees are foraging in treatment areas.

Momfluorothrin is efficacious against several pests of public health concern, including flies, 

mosquitoes, wasps, hornets, yellow jackets, roaches, ticks, bed bugs, scorpions, centipedes, and 

certain species of ants and spiders. Public health pests may cause painful bites and stings, 

allergic reactions, transmission of disease (e.g., West Nile virus, Lyme disease), and even death. 

The Agency considers products that control these pests to be in the public’s interest. 

7.2.1 Endangered Species Act Considerations

Results from EPA’s screening-level ecological risk assessment indicate that the proposed uses of 

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

taxon. Thus, a "no effect" determination is made. 

The NAS report, available at http://www.nap.edu/catalog.php?record_id=18344, outlines 

recommendations on specific scientific and technical issues related to the development of 
Page 20 of 21

pesticide risk assessments that are compliant with the Endangered Species Act and the 

Federal Insecticide, Fungicide, and Rodenticide Act. In November, the EPA, along with 

the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service 

(NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA), 

released a summary of their joint Interim Approaches for assessing risks to listed 

species from pesticides. The Interim Approaches were developed jointly by the Agencies 

in response to the NAS’s recommendations and reflect a common approach to risk 

assessment shared by the Agencies as a way of addressing scientific differences between 

EPA and the Services. The joint Interim Approaches were released prior to the 

stakeholder workshop held on November 15, 2013. EPA presented the joint Interim 

Approaches at the December 2013 PPDC (Pesticide Program Dialogue Committee) and 

SFIREG (State FIFRA Issues Research and Evaluation Group) meetings, allowing 

additional opportunities for stakeholders to comment on the Interim Approaches. As 

discussed at the November 2013 workshop, and consistent with the March 2013 

stakeholder engagement process for FIFRA-ESA consultations, the Agencies have 

invited comment on the Interim Approaches as preparations are made to apply these new 

approaches in the context of upcoming registration review decisions. The Agencies 

intend to jointly implement these approaches as part of a phased iterative process that 

takes account of the input received and the lessons learned from the initial efforts to work 

with the Interim Approaches. 

It is important to understand that the development of the Interim Approaches does not by 

its terms suggest that existing or recently developed risk assessments using the criteria 

articulated in OPP’s 2004 Overview document are necessarily “under-protective.” The 

Interim Approaches are intended to identify interim thresholds for interagency review as 

the Agencies jointly work to implement the recommendations of the NAS on certain 

specific registration review actions. The Agencies have made no determination that these 

thresholds are necessary to prevent take and preclude likely jeopardy and, in any case, the 

Interim Approaches do not establish legally binding thresholds for consultation under the 

Services’ implementing regulations. As EPA and the Services work through the initial 

actions that are being reviewed under the Interim Approaches, the Agencies will 

determine whether these thresholds should be modified before they are extended more 

broadly to additional regulatory actions. The details of the joint Interim Approaches are 

contained in the white paper “Interim Approaches for National-Level Pesticide 

Endangered Species Act Assessments Based on the Recommendations of the National 

Academy of Sciences April 2013 Report,” dated November 1, 2013, available at 

http://www.epa.gov/espp/2013/nas.html. 

7.3 Data Requirements

There are no outstanding data requirements at this time for momfluorothrin. Outdoor use 

expansions including broadcast applications would trigger additional data requirements.

7.4 Mitigation and Labeling Requirements

In order to mitigate potential risks to fish, aquatic invertebrates, and terrestrial invertebrates, the 

applicants have agreed to add the following labeling language, which is intended to reduce the 
Page 21 of 21

area of potential exposure to momfluorothrin residues by reducing inadvertent off-target 

exposure via drift and runoff:

 This pesticide is highly toxic to fish and aquatic invertebrates. Drift and runoff may be 

hazardous to aquatic organisms in water adjacent to treated areas.

 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 product is highly toxic to bees exposed to direct treatment on plants or weeds. Do not 

apply this product while bees are foraging. Do not apply this product to plants that are 

flowering. Only apply after all flower petals have fallen off.

 All outdoor applications must be limited to crack-and-crevice or spot surface treatments only.

All outdoor applications to impervious surfaces such as sidewalks, driveways, patios, porches 

and structural surfaces (such as windows, doors and eaves) are limited to spot and crack-andcrevice applications only.

 Do not apply to directly to water. Do not apply within 25 feet of lakes, streams, ponds, 

estuaries, oceans or other waters.