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 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

Date: October 20, 2014

PC Code: 047201

DP Barcode: 419153

MEMORANDUM 

Subject: Registration Review –Preliminary Ecological Risk Assessment and 

Endangered Species Effects Determination for Dipropyl 

isocinchomeronate (aka Morpel® Repellent 326, formerly MGK®

Repellent 326) 

To: Marianne Mannix, Chemical Review Manager 

 Patricia Parrott, Branch Chief 

 Risk Management and Implementation Branch III 

 Pesticide Re-evaluation Division 

From: Melanie Biscoe, Physical Scientist 

 Katherine Stebbins, Biologist 

 Environmental Risk Branch 3 

 Environmental Fate and Effects Division 

Reviewed Melissa Panger, Ph.D., Senior Scientist

By: Environmental Risk Branch 3 

 Environmental Fate and Effects Division 

Through: Dana Spatz, Branch Chief 

 Environmental Risk Branch 3 

 Environmental Fate and Effects Division 

 Office of Pesticide Programs 

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

ecological risk assessment and endangered species effects determination for the 

registration review of the insect repellant, dipropyl isocinchomeronate (formerly MGK®

Repellent 326 or MGK-326, hereafter referred to as Morpel®) (PC code 047201; CAS: 

136-45-8). An evaluation of potential risk to aquatic and terrestrial organisms as a result 

of the use of Morpel® is summarized below. 

 
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Morpel® is an insect repellent used in human and domestic animal insect sprays 

(specifically for dogs, cats and horses), lotions, ready-to-use wipes, and a dog and cat dip. 

Morpel® sprays are also used in indoor premises. Morpel® is never used as the sole 

active ingredient; rather, it is used to broaden the spectrum of repellency of other 

formulation components, such as DEET (N,N-diethyl-m-toluamide) (PC code 080301), to 

repel flies, gnats, and other flying and biting insects. 

Because of Morpel®’s very low use diffused over a large treatment area, as well as the 

low probability of non-target organism exposure to Morpel®, EFED presented an analysis 

of the preliminary “no effect” determination for the registered uses of Morpel® to the 

OPP Science Policy Council/Risk Management Forum’s De Minimis Subgroup (DMS). 

The DMS concurred with the ‘no effect’ determination and recommended that EFED 

prepare an abbreviated ecological risk assessment for Morpel® to present the conclusion 

of no unreasonable adverse effects to non-listed species, and no reasonable expectation of 

effects to federally listed threatened or endangered species (De Minimis Subgroup 

Opinion on Morpel®, May 14, 2014). This preliminary ecological risk assessment 

presents data and results comparable to those presented to the De Minimis Subgroup 

along with additional supporting information related to the active ingredient (a.i.). 

The results of this assessment on currently registered Morpel® uses indicate that there are 

no level of concern (LOC) exceedances to listed or non-listed fish or aquatic 

invertebrates, and no reasonable expectation of effects to birds, reptiles, amphibians, 

mammals and plants. The EPA makes a No Effects (NE) determination for all Federallylisted species and a No Habitat Modification determination for all designated critical 

habitats for the currently registered uses of Morpel®. 

Conclusions regarding aquatic animals are based on lack of acute LOC exceedances in 

the risk estimation. RQs were not calculated for aquatic plants as toxicity data were not 

available; however, based on the large margin of safety observed for other aquatic 

taxonomic groups and toxicity estimates from structure activity relationship modeling, 

direct risk to aquatic plants are not expected. In addition, there are currently no known 

incidents involving Morpel® and aquatic organisms. 

Conclusions regarding terrestrial organisms and plants are based on the low probability of 

exposure to non-target organisms. For example, exposure in terrestrial habitats is not 

expected as the products formulated as lotions or impregnated wipes would be applied 

directly to the skin/animal and spray products would likely be applied at distances of less 

than 10 inches from the intended application sites (human skin/dog, cat, horse skin and 

hair). Thus, exposure to terrestrial organisms is not expected because they would not 

likely come in close contact with humans or domestic animals1

 (i.e., the registered use 

sites). Even if a non-target organism was to come into contact with Morpel® from overspray or through contaminated food items, the exposure levels would be expected to be 

low. Therefore, given its low toxicity profile (for terrestrial animals), effects to non-

 

1

 Throughout this assessment, the term “domestic animals” is defined as dogs, cats, and horses because they 

are the specific use site on the label. 
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target organisms would not be anticipated to exceed concern levels even if exposure 

occurred. 

Data are not available to assess the risk to non-target terrestrial invertebrates; however, 

given that Morpel® is an insect repellent (that is also co-formulated with repellents and/or 

toxicants), the potential exposure is likely only due to chance (e.g., flying through the 10 

inch spray directed at the human/horse or landing on the human/horse). Additionally, 

Morpel® is expected to remain on the target (i.e., it is not expected to volatilize) and the 

repelling action of the formulated active ingredients is expected to reduce the magnitude 

and duration of exposures. Exposure to terrestrial plants is not expected; thus, there is no 

risk expected for plants. 

1. PROBLEM FORMULATION 

Conclusions from Previous Risk Assessments 

EFED has not conducted any ecological risk assessments for Morpel®. The Re-registration 

Eligibility Document (RED) for dipropyl isocinchomeronate, signed September 23, 2003, 

stated that: 

The Agency did not conduct an environmental risk assessment because MGK

® 

Repellent 

326 is an “indoor residential” use pesticide and MGK

® 

Repellent 326 is not likely to 

result in exposures and risks to non-target organisms. 

While Morpel® was previously classified as an “indoor residential” pesticide because of 

the limited potential to reach aquatic and terrestrial environments, this assessment will 

consider potential exposures that may occur from product applications outdoors, from 

people and domestic animals being outdoors subsequent to application, and from release 

of contaminated household wastewater into the environment. 

Nature of Chemical Stressor 

Morpel® is never used as the sole active ingredient (a.i.); rather, it is used to expand the 

spectrum of repellency/efficacy of other formulation components (such as DEET and NOctyl bicycloheptene dicarboximide). The mode of action for repellency is unknown, 

however, in some cases it is used for improving the repellency of DEET products by 

preventing evaporation2

. 

Morpel® repellent products are formulated as emulsifiable/soluble concentrates, ready to 

use spray/pressurized liquids, and as impregnated materials (towelettes). Table 1

provides a summary of the types of registered products. For humans, Morpel® may be 

applied via spray/aerosol mist and towelettes. For domestic animals, applications may be 

 

2

 Brassard, D., Haddad, S., Ranville, M. BEAD Chemical Profile (BCP) for Registration Review: 

Dipropyl isocinchomeronate (PC Code 047201). April 28, 2014. 
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made as a spray, wipe-on, or towelettes. Additionally, for dogs and cats, Morpel® may be 

applied via a pet dip application. The ready-to-use products for human use are 

formulated at or below a concentration of 2.5% a.i. by weight. The dip products for cats 

and dogs are sold as a concentrate (1.94-4% a.i.) which is diluted prior to use. Other 

spray (ready-to-use and concentrated) and wipe-on products for domestic animals are 

formulated at or below a concentration of 2.5% a.i. by weight. There are currently 40 

registered products for Morpel®. 

Table 1 provides information on the 11 registrations that represent the range of Morpel®

end-use products. Three of these 11 products were used to calculate EECs for Morpel®

because they were expected to result in the highest environmental exposures and are 

listed in bold in the table. 

Table 1. Representative Uses for MORPEL 

Product For Use On... EPA Reg. 

Number 

% Active 

Ingredient Formulation Type 

Product 

container 

size 

Towelette horses 10088-97 1.76 Impregnated 

Materials Towelette 

Dip dogs and cats 2382-89 4.0 Soluble Concentrate 1 gallon 

(concentrate) 

Wipe-on horses 270-253 0.5 Ready-to-Use 

Solution Not specified 

Spray mist dogs, cats, 

horses 270-300 1.0 Ready-to-Use Solution Not specified 

Dilute, then 

spray 

dogs, cats, 

horses 270-301 2.5 Emulsifiable Concentrate Not specified 

Dilute, then 

spray 

horses 270-326 2.5 Emulsifiable 

Concentrate Not specified 

Spray dogs, cats, 

horses 270-343 0.5 Ready-to-Use Solution 16 fl. oz. 

Ear lotion dogs, cats, 

horses 270-345 1.0 Ready-to-Use Solution Not specified 

Dip dogs and cats 270-349 1.94 Soluble Concentrate Not specified 

Wipe-on/Spray 

mist horses 40322-2 1.17 Ready-to-Use Solution 32 fl. oz. 

Spray Human and 

horse use 54287-13 2.5 Ready-to-Use Solution Not specified 

Spray human use 7754-41 2.5 Ready to UseAerosol 12 oz. can 
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Exposure Characterization 

The structure and physicochemical characteristics of Morpel® are summarized in Table 

2. Based on its vapor pressure, Morpel® is not expected to volatilize under field 

conditions. Because of its limited use pattern, the only environmental fate study required 

to be conducted for Morpel® was hydrolysis. Morpel® remains stable under acidic 

conditions, as no degradation was observed at pH 5 during the 30 days of the hydrolysis 

study. However, Morpel® hydrolyzes in neutral (pH 7 half-life=17 days) and alkaline 

environments (pH 9 half-life=14 hours) (MRID 43073601). 

 

Table 2. MORPEL: Structure & Physicochemical Properties 

Parameter Value

Structure 

Molecular formula C13H17NO4

Molecular weight 251.3 g/mol 

Water solubility 892 mg/L at 20oC 

Vapor pressure 4.92 x 10-7 mm Hg at 25°C 

Octanol-water partition coefficient (log Pow) 3.567 

Melting Point n/a – liquid at room temperature 

Boiling Point 150oC 

Dissociation constant (Ka) 0.119 at 25°C 

Residues of Concern 

Based on the hydrolysis study (MRID 43073601), Morpel® produces three degradates: 

 5-propyl, 2,5-pyridine dicarboxylate (35% of the total applied, day 30, pH 7) 

 2-propyl, 2,5-pyridine dicarboxylate (33.1% of the total applied, day 30, pH 7) 

 2,5-pyridine dicarboxylate (95% of the total applied, day 14, pH 9 only) 
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Toxicity data for the transformation products have not been submitted, and this 

assessment assumes that the degradates are to be equal or less toxic than the parent 

compound. In this assessment, exposures are estimated under the conservative 

assumption that Morpel® does not degrade in the environment. This assumption 

addresses any potential concerns regarding exposure of non-target organisms to Morpel®

degradates in the environment. 

Ecological Effects 

The most sensitive endpoint for each taxon is used for risk estimation. For this 

assessment, evaluated taxa include freshwater fish (surrogate for aquatic-phase 

amphibians), freshwater invertebrates, birds (surrogate for terrestrial-phase amphibians 

and reptiles), and mammals. Table 3 provides a summary of the taxonomic groups and 

the surrogate species tested to characterize the potential acute and chronic ecological 

effects of Morpel®. In addition, the table provides a preliminary overview of the 

potential acute toxicity of Morpel® by providing the acute toxicity classifications. 

Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of 

MORPEL and the Associated Acute Toxicity Classification. 

Taxonomic 

Group Study Type 

Tested 

Species 

Toxicity 

Endpoint 

Toxicity 

Classification 

Study MRID 

and 

Classification 

Birds 

Acute Oral 

Bobwhite quail 

(Colinus 

virginianus) 

LD50=1560 

mg/kg- bw 

Slope: 4.3 

Slightly toxic 41882601 

(Acceptable) 

 Avian Subacute 

(5-day dietary) 

Bobwhite quail 

(Colinus 

virginianus) 

LC50 = 5,000 mg 

a.i./kg diet 

Practically 

nontoxic 

41685502 

(Acceptable) 

Mallard duck 

(Anas 

platyrhyncos) 

LC50= >5,620 mg 

a.i./kg diet 

No mortalities. 

NOAEC=3160 

mg a.i./kg diet 

based on reduced 

body weight gain 

at 5630 mg a.i./kg 

diet. 

Practically 

nontoxic 

41685501 

(Acceptable) 

Mammals 

Acute (oral) 

Laboratory rat 

(Rattus 

norvegicus) 

LD50=5120 mg 

a.i./kg (male and 

female)

Practically 

nontoxic 

00155068 

(Acceptable)3

 

Chronic 

(2 generation) 

NOAEL=65 mg 

a.i./kg/day Based 

on decreased pup 

body weight on 

lactation days 14-

21 at 250 mg 

a.i./kg/day 

-- 41547801 

(Acceptable) 3
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Taxonomic 

Group Study Type 

Tested 

Species 

Toxicity 

Endpoint 

Toxicity 

Classification 

Study MRID 

and 

Classification 

Freshwater 

fish2 Acute 

 Bluegill 

Sunfish 

(Lepomis 

macrochirus) 

LC50=0.44 mg 

a.i./L 

NOAEC= 0.17 mg 

a.i./L based on 

signs of toxicity at 

doses ≥0.32 mg 

a.i./L 

 

42174501 

(Acceptable) 

Highly toxic 

Rainbow trout 

(Oncorhynchus 

mykiss) 

LC50=1.0 mg 

a.i./L Slope= 14 

NOAEC= 0.68 mg 

a.i./L based on 

signs of toxicity 

and mortality at 

doses ≥ 1.5 mg 

a.i./L 

 

41911401 

(Acceptable) 

Highly toxic 

Freshwater 

invertebrates Acute 

Daphnid 

(Daphnia 

magna) 

EC50=18 mg 

a.i./L Slope =8 Slightly toxic 41525302 (Acceptable) 

1 Birds are considered surrogates for terrestrial-phase amphibians and reptiles. 

2

 Freshwater fish are considered surrogates for aquatic-phase amphibians. 

3

 Study classification made by Health Effects Division (HED). 

For aquatic organisms, data are available for freshwater fish and invertebrates on an acute 

exposure basis. Morpel® is classified as “highly toxic” to fish [Bluegill (Lepomis 

macrochirus) LC50 = 0.44 mg a.i./L] and “slightly toxic” to invertebrates [Daphnid

(Daphnia magna) EC50=18 mg a.i./L). Toxicity data were not available for evaluation of 

chronic exposure to fish and invertebrates. Additionally, data were not available for 

vascular and non-vascular aquatic plants. However, the ECOSAR (structure activity 

analysis) predicted toxicity values for green algae as well as the chronic toxicity values 

for fish and aquatic invertebrates were within the toxicity values from the submitted data 

for aquatic taxa, thus, in this analysis, the acute endpoints serve as a proxy in the absence 

of data. See Appendix B for ECOSAR output. 

On an acute oral exposure basis, Morpel® is classified as “slightly toxic” to birds [LD50= 

1560 mg a.i./kg-bw] and based on dietary exposure, Morpel® is classified as “practically 

non-toxic” [5-day dietary LD50 value = 5,000 mg a.i./kg diet]. For mammals, Morpel® is 

classified as “practically nontoxic” on an acute exposure basis [acute oral LD50= 

5,120 mg a.i./kg-bw]. On a chronic exposure basis, the reported NOAEL of 65 mg 

a.i./kg/day was based on a decrease in pup body weight at the 250 mg a.i./kg/day 

treatment level. Chronic data are not available for birds. 

Morpel® toxicity data are not available for bees, non-target insects, or terrestrial plants. 

In an attempt to gain a better understanding of the toxicity to terrestrial invertebrates, 

several efficacy studies were reviewed (MRIDs: 47390700, 46580201, 46106200, 
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00067102, 00115944), however, the interpretation was complicated because the products 

tested were often co-formulated with other active ingredients and repellency (rather than 

toxicity) was generally the focus of the studies, thus, no further information was gained. 

Open Literature 

A query of the open literature via the Web of Science Database was conducted for “MGK326”,“dipropyl isocinchomeronate”, and “Morpel”. No studies conducted for ecological 

effects were reported. 

Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological receptors (a biological 

entity) that is exposed to a stressor (USEPA, 1998a) in biologically significant 

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

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

complete, it must have a source, a release mechanism, an environmental transport 

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

Risk Hypotheses

For the Morpel® national-level ecological risk assessment, the following ecological 

exposure and risk hypotheses are being employed: 

1) Morpel®, when used in accordance with current labels, can result in offsite movement of the compound via wash-off by treated individuals 

entering water bodies as well as from showering/bathing and pet dips 

leading to exposure of non-target aquatic plants and animals including 

federally-listed threatened and endangered species. 

2) Based on the proposed use patterns and the sensitivity of non-target 

aquatic species, the proposed uses of Morpel® have the potential to 

reduce survival, reproduction, and/or growth in aquatic animals and 

plants through off-site movement of the compound via wash-off by 

treated individuals entering water bodies as well as from 

showering/bathing and pet dips leading to exposure of non-target 

aquatic plants and animals (including federally-listed threatened and 

endangered species).

3) Direct applications of Morpel® to human skin and domestic animals are 

not expected to result in significant exposure to non-target terrestrial 

plants and animals including federally-listed threatened and 

endangered species. 

Wash-off from treated individuals by swimming, bathing, and pet dips may result in the 

movement of Morpel® into aquatic environments (water and sediment). Based on the use 
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characteristics, runoff, spray drift, leaching, and atmospheric deposition are unlikely to 

result in aquatic or terrestrial exposures to non-target plants and organisms. For Morpel®, 

the potential exposure pathways include wash-off from skin when treated individuals 

enter water bodies (e.g., for recreation), wash-off from treated humans or pets into 

household wastewater (and subsequent release into the environment), and inadvertent 

release of pet dip into household wastewater (and subsequently into the environment) 

during the dipping process. 

Exposure in terrestrial habitats would be limited to human skin as well as domestic pet 

skin and hair. Products formulated as lotions or impregnated wipes would be applied 

directly to the human skin. Many other product labels specify recommended spray 

distances of less than 10 inches from the intended application sites (human skin/horse 

skin and hair). Any movement away from the site of application represents potential 

exposure pathways for a broad range of biological receptors of concern (non-target 

terrestrial animals and plants), however, the amount of Morpel® resulting from human or 

pet applications in the terrestrial environment (air, ground, drinking water, plants, or nontreated animals) is considered negligible. 

Analysis Plan 

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

environment is estimated. The use, environmental fate, and ecological effects of Morpel®

are characterized and integrated to assess the risks. This is accomplished using a risk 

quotient (ratio of exposure concentration to effects concentration) approach. 

 

Measures of Exposure 

Aquatic ecosystems potentially at risk from Morpel® exposure include (1) water bodies 

entered by treated humans or horses, as well as any water bodies adjacent to, or 

downstream from the water bodies entered, and (2) water bodies into which domestic 

wastewater is ultimately released. 

Measures of aquatic exposure are typically based on models that predict estimated 

environmental concentrations (EECs) of Morpel® such the Pesticide Root Zone 

Model/Variable Volume Water Model (PRZM/VVWM) and Surface Water 

Concentration Calculator (SWCC) Graphic User Interface (GUI). Because of the limited 

application methods (directly to human/domestic pet skin/hair), the typical models used 

for exposure estimation will not be used in this assessment. Additionally, because 

limited laboratory fate data are available for Morpel®, this assessment assumes that 

Morpel® does not degrade in the environment. 

It is assumed that Morpel® reaches surface water when treated humans or horses enter a 

water body and the applied Morpel® is washed off, remaining in the water column. Water 

concentrations are estimated under the assumption that 100% of the applied a.i. (from 10 

or 100 treated adults or 10 horses) is diluted in the standard farm pond on a single day. 

Additionally, water concentrations are estimated under the assumption that 50 cans of 
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product are diluted in the standard farm pond on a single day. 

Given the small size of the modeled water body, 10 and 100 swimming adults and 10 

horses represent low, moderate, and high aquatic exposures, respectively. Application of 

the equivalent of 50 cans of product represents a highly unlikely, very conservative 

aquatic exposure scenario. The scenarios chosen are intended to evaluate the plausibility 

of exposure levels approaching those that may cause concern for aquatic organisms. 

It is also assumed that Morpel® reaches surface water through local wastewater systems 

when humans or pets bathe, or when there is inadvertent release of pet dip down the 

household drain. Water concentrations are estimated using the Exposure and Fate 

Assessment Screening Tool’s (E-FAST v.2.0) Down-the-Drain module, which may be 

accessed at http://www.epa.gov/oppt/exposure/pubs/efast.htm. Additionally, water 

concentrations are estimated using a more conservative approach of diluting several 

gallons of pet dip concentrate or several gallons of pet dip that is diluted per label 

instructions into a single 1–hectare water body. Applying several gallons of dip 

concentrate or dip solution to the farm pond represents an extremely conservative screen 

for aquatic exposures. 

Because of the application method and limited scope of use sites for Morpel®, terrestrial 

ecosystems potentially at risk are limited to the area in which treatment occurred (e.g.,

spray application to human or horse). For this assessment, exposure to non-target 

terrestrial organisms via contact with humans/horses or through overspray is presumed 

negligible and will not be estimated. 

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 3). 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. Birds represent surrogates for 

terrestrial-phase amphibians and reptiles, and freshwater fish represent surrogates for 

aquatic-phase amphibians. No additional non-target ecotoxicity data are available on 

Morpel®. 

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. For the screening-level risk assessment of 

Morpel®, the deterministic risk quotient (RQ) method is used to assess risk to aquatic 

organisms by comparing the estimated exposure concentrations with the 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) (Table 4). These criteria are used to 

indicate when applications of Morpel®, as directed on the proposed labels, have the 
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potential to cause adverse effects to listed and non-listed non-target organisms. The risk 

to terrestrial organisms is considered qualitatively given the limited potential for 

exposure. 

Table 4. Agency Acute Risk Quotient (RQ) Metrics and Levels of Concern (LOC) for 

Aquatic Animals (fish and invertebrates) 

RISK CLASS RISK DESCRIPTION RQ LOC 

Acute Potential for effects to non-listed animals from acute 

exposures 

Peak EEC/LC501 0.5 

Acute Restricted Use 

Potential for effects to animals from acute exposures 

Risks may be mitigated through restricted use 

classification 

Peak EEC/LC501 0.1 

Acute Listed Species Listed species may be potentially affected by acute 

exposures 

Peak EEC/LC501 0.05 

1 LC50 or EC50. 

2. RISK CHARACTERIZATION 

Risk Estimation 

Four representative end-use products were selected for estimating exposures. Bug Barrier 

II, (EPA Reg. No.7754-41, 2.5% a.i.) was selected to represent the highest quantity of 

Morpel® in a single sale container formulated for use on humans. B Free of Flies (EPA 

Reg. No. 40322-2, 1.17% a.i.) was selected to assess the exposure via applications to 

horses because it had an application rate on a per animal basis. DEET PLUS® 

COMPOSITE SPRAY II INSECT REPELLENT (EPA Reg. No. 54287-13, 2.5% a.i.) 

was selected to estimate the exposures from horse applications because it had the highest 

percent a.i. Finally, PYRE-SECT dip (EPA Reg. No. 2382-89, 4% a.i.) was selected to 

assess the pet dip applications because it had the highest percent a.i. for the pet dip uses. 

Personal Application, Reg. Number: 7754-41: This product represents the highest rate 

of application to humans. It is formulated as a ready to use pressurized liquid (2.5% a.i.) 

that is sold in 12 oz. cans. The other ready-to-use product (also 2.5% a.i.) specified for 

human use does not state the container size; therefore, a 12 oz. can was assumed for this 

product as well. 

In this preliminary assessment, we consider three scenarios. In the first two scenarios, 10 

and 100 people have applied aerosol spray to themselves and then go swimming in the 

farm pond, whereby 100% of the applied a.i. is washed off into the farm pond. In the 

third scenario, 50 cans of product are dumped into the farm pond. These scenarios are 

consistent with those used to assess ecological risk from personal applications of DEET 

products in the DEET Preliminary Risk Assessment (DP399065). 

Table 5 includes the estimate of a.i. applied to one human in one day, while Table 6

includes the estimated exposure concentrations in the farm pond for the three scenarios. 
Page 12 of 21 

Amongst the scenarios, the highest exposure concentration in the farm pond is estimated 

to be 0.0196 mg a.i./L and is based on the scenario where 50 cans of product are dumped 

into the farm pond. 

Horse Application: For product “B Free of Flies” (EPA Reg. No. 40322-2) , the directions 

state to apply up to 2 ounces per head per day using either a soft cloth or a fine mist 

spray. This equates to 597 mg a.i./individual animal per day3

. For the DEET PLUS® 

COMPOSITE SPRAY II INSECT REPELLENT (2.5% a.i.-Reg# 54287-13), the exposure 

estimate for an individual horse is 537 mg a.i./individual animal per day (Table 5). 

In this preliminary assessment for horse applications, we consider a conservative scenario 

where 10 horses are sprayed or wiped with Morpel® formulated products and 

subsequently swim in the farm pond. These scenarios are comparable to those used to 

assess ecological risk from horse applications of DEET products in the DEET 

Preliminary Risk Assessment (DP399065). 

Table 5 includes the estimate of a.i. applied to one horse in one day, while Table 6 

includes the estimated exposure concentrations resulting from 10 horses swimming in the 

farm pond after product application. For both of the products assessed, the exposure 

concentration in the farm pond is estimated to be 0.0003 mg a.i./L. 

Table 5. Amount of MORPEL Applied to One Human or Horse in One Day Repellent Amount of a.i. in product (mg a.i./ mg product) Formulation- Specific Application Ratea (mg product/ cm2 skin) Fraction of Body Exposeda Surface Area to Body Weight Ratioa (cm2/kg) Exposure Timea (hr./day) Application Frequencya (# applications/ hr.) Exposure (mg a.i./ kg-day)b Individual Exposure (mg a.i./ individual/day)c

Human 

(aerosol 

spray, 

Reg# 

7754-41) 

0.025 1.10 0.75 280 3.7 0.25 5.34 427 

Horse 

(pump 

spray 

Reg# 

54287-13 

) 

0.025 0.62 0.75 100 3.7 0.25 1.08 537 

a

 For adult human applications, these values were determined using default values from HED's SOPs as of July 11, 

2011. For horses, the surface area per body weight and body weight values are 100 cm2/kg and 500 kg, 

respectively, based on an online resource cited in the 2011 DEET Preliminary Risk Assessment. 

b Exposure calculated by multiplying the values in the preceding six columns (see Standard Operating Procedures 

for Residential Pesticide Exposure Assessment at http://www.epa.gov/pesticides/science/residential-exposuresop.html for details). 

c

 Individual exposure calculated by multiplying estimated body weight (80 kg for adult humans and 500 kg for 

horses) by exposure (mg a.i./kg-day) from the preceding column. 

 

3 2 fl. oz. product /horse x 1 gal/128 fl. oz. x 7.2 lbs product/gal x 453590 mg/lb *1.17% a.i.=597mg a.i./horse 
Page 13 of 21 

Table 6. Estimated Concentration of MORPEL in the Standard Farm Pond

End-use 

product Scenario Total mg a.i. applied 

Concentration in 

farm pond 

(mg a.i./L) 

Human 

(aerosol 

spray, Reg# 

7754-41) 

10 

adults 4,274 0.0002 

100 

adults 42,735 0.0021 

50 cans 

product 393,875a

 0.0196 

Horse 

(pump spray 

Reg# 54287-

13 ) 

10 

horses 5,377 0.0003 

Horse 

(wipe/spray, 

Reg# 

40322-2) 

10 

horses 5970 0.0003 

a 50 cans x12 oz. product/can x 29.5735ml/oz. x 0.8879 g product/ml x 

1000 mg/g x 2.5% a.i.

Pet Dip Application, Reg. Number: 2382-89: This is a pet (dog and cat) dip product sold 

as a 1 gallon concentrate solution and has the highest percent a.i. of all pet dip products. 

The directions state that a maximum of 1 fluid ounce of product should be added to 1 

gallon of water prior to use. Additionally, the label establishes a minimum re-application 

interval of 7 days. 

In this preliminary assessment, we consider a conservative “down-the-drain” scenario 

where aquatic exposure concentrations are estimated using E-FAST v.2.0. Conceptually, 

the E-FAST model assumes that in a given year the entire production volume of a 

chemical (i.e., a pesticide) is parceled out on a daily basis to the entire U.S. population 

and converted to a mass release per capita and daily per capita release to a wastewater 

treatment facility (i.e., g/person/day). This mass is then diluted into the average daily 

volume of wastewater released per person to arrive at an estimated concentration of the 

chemical in wastewater prior to entering a treatment facility. The chemical’s 

concentration in untreated wastewater is then reduced by the fraction removed during 

wastewater treatment processes before release into a river or stream where it undergoes 

dilution. The inputs used in this model are described in Table 7, as well as the resulting 

10th percentile surface water exposure estimate, 0.0186 μg/L, which is four orders of 

magnitude lower than the most sensitive toxicological endpoint for aquatic organisms. 

The complete inputs and outputs from the E-FAST v.2.0 model is included in Appendix 

B. 

In addition to the E-FAST modeling, we consider an extremely conservative scenario in 

which 2 gallons of pet dip concentrate are dumped into the standard farm pond. This 

results in a concentration of 0.015 mg a.i./L in the farm pond. With regard to the applied 

pet dip solution (i.e., 1 fluid ounce of concentrate diluted into 1 gallon of water), 
Page 14 of 21 

dumping 1,251 gallons of pet dip solution into the farm pond results in a concentration of 

0.020 mg a.i./L. See Table 8 for estimated exposure concentrations calculated for pet 

dips using this screen. 

Table 7. Pet Dip “Down-the-Drain” Exposure Estimates using E-FAST v.2.0

E-FAST v.2.0 Inputs Value Source 10th Percentile Surface 

Water Exposure Estimate 

Total Expected Wastewater 

Treatment Removal 14.72% EPISUITE v.4.1 

0.0186 μg/L 

Production Volume 898 kg a.i./year Registrant Data 

Bio-Concentration Factor 105.3 L/kg wetweight 

EPISUITE v.4.1 

Regression-Based Method 

of Calculation 

Table 8. Pet Dip Screen: Exposure Estimates via Farm Pond Dilution

Scenario 

Liters of 

Concentrate 

or Solution 

Applied 

Total mg a.i. 

applied 

Total liters in 

farm pond 

Concentration 

in farm pond 

(mg a.i./L) 

328 gallons 

solution 1,251 390,320 20,001,251 0.020 

2 gallons 

concentrate 8 304,640 20,000,008 0.015 

Surface Water Concentrations of Morpel® Based on Monitoring 

Surface water and sediment monitoring data from NAWQA and California Department of 

Pesticide Regulation are not available for Morpel®. 

Potential Risk to Terrestrial Organisms 

Exposure to non-target terrestrial organisms and plants is presumed negligible due to the 

limited exposure potential (terrestrial plants and animals) and relatively low toxicity 

(terrestrial vertebrates), thus, the potential for risk is not estimated. 

Potential Risk to Aquatic Organisms 

The expected concentrations of Morpel® in the aquatic environment are orders of 

magnitude lower than the available aquatic LC50 and EC50s determined for Morpel®

(Table 9), and, thus, the potential for risk to aquatic species is low. 
Page 15 of 21 

Table 9. Aquatic exposure estimates and RQs for Morpel®

End-use product % 

a.i. 

Total 

application 

EEC 

(mg a.i./L in 

pond) 

Acute Fish RQ 

(EndpointLC50=0.44 

mg a.i./L) 

Acute 

Invertebrate RQ 

(Endpoint-EC50

= 18 mg.a.i./L)

Bug Barrier II (EPA 

Reg. No.7754-41); 

Aerosol Spray 

2.5 

10 adults 0.0002 0.0005 1.19 x 10-5

100 adults 0.0021 0.0049 0.0001 

50 cans 0.0196 0.0445 0.0011 

B Free of Flies (EPA 

Reg. No. 40322-2); 

wipe-on/spray

1.17 10 treated 

horses 0.0003 0.0007 1.6 x10-5 

DEET PLUS® 

COMPOSITE 

SPRAY II INSECT 

REPELLENT 

(EPA Reg. No. 

54287-13)

2.5 10 treated 

horses 0.0003 0.0007 1.6 x10-5

PYRE-SECT dip 

(EPA Reg. No 2382-

89); dog and cat dip 

4.0 

898 kg a.i./yr 

1.86 x 10-5

(concentration 

released to a 

water body) 

4.23 x 10-5 1.03 x 10-6

328 gallons 

solution 0.020 0.04 0.001 

2 gallons 

concentrate 0.015 0.03 8 x 10-4

No LOC exceedances 

Acute risk to non-listed species LOC for aquatic organisms is 0.5 

Acute risk to listed species LOC for aquatic organisms is 0.05 

Incident Database Review 

A review of the following databases was completed in April (2014): 

 Ecological Incident Information System (EIIS) 

 OPP Aggregate Incident Reports database 

 Avian Monitoring Information System (AIMS) 

http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims) 

There were no reported incidents for Morpel®. 
Page 16 of 21 

Risk Description 

Aquatic Organisms 

The results of risk estimation indicate that registered uses of Morpel® will not result in 

LOC exceedances for acute risk to fish and invertebrates. Chronic RQs were not 

calculated; however, given the ECOSAR-estimated toxicity values were similar (within 

an order of magnitude) for the acute and chronic endpoints and that RQs were only 

approaching an exceedance in the most conservative and highly unlikely scenarios, 

chronic risk to fish and invertebrates is not expected. 

RQs were not calculated for aquatic plants as toxicity data were not available. EFED 

presumed direct risks were lower than concern levels to aquatic plants given the 

ECOSAR-estimated toxicity and lack of exceedances for other aquatic organisms. Also, 

there are no reported incidents for aquatic organisms or plants. 

Terrestrial Organisms 

Exposure in terrestrial habitats is not expected as the products formulated as lotions or 

impregnated wipes would be applied directly to the skin/animal and spray products would 

likely be applied at distances of less than 10 inches from the intended application sites 

(human skin/horse skin and hair). Thus, exposure to terrestrial organisms is not expected 

because they would not likely come in close contact with humans or domestic animals 

(i.e., the registered use sites). Even if a non-target organism were to come into contact 

with Morpel® from over-spray or through contaminated food items the exposure levels 

would be expected to be low; therefore, given its low toxicity profile (for terrestrial 

animals), effects to non-target organisms would not be anticipated to exceed concern 

levels even if exposure occurred. 

Data are not available to assess the risk to terrestrial invertebrates; however, given that 

Morpel® is an insect repellent (that is also co-formulated with other repellents), the 

potential exposure is likely only due to chance (e.g., flying through the 10 inch spray 

directed at the human/horse or landing on the human/horse). Additionally, the repelling 

action of the formulated active ingredients will also reduce the likelihood of such 

occurances. Exposure to terrestrial plants is not expected, thus, there is no risk expected 

for plants. 

Uncertainties and Data Gaps 

Although only a hydrolysis study was required by and submitted to the EPA, additional 

fate data would not change the risk conclusions in this assessment. The exposure 

modeling conducted assumed that Morpel® is stable to all degradation and dissipation 

processes. 

 
Page 17 of 21 

Few ecotoxicity studies have been submitted to the EPA. However, under the currently 

registered use patterns, EFED has concluded (1) low likelihood of risk to aquatic 

organisms and (2) highly unlikely exposure to terrestrial organisms. Unless the use 

patterns of Morpel® change through proposed registrations of new products, EFED 

considers the current ecotoxicity database to be sufficient. 

3. ENDANGERED SPECIES ASSESSMENT 

The results of this assessment on currently registered Morpel® uses indicate that there are 

no level of concern (LOC) exceedances to listed or non-listed fish or aquatic 

invertebrates, and no reasonable expectation of effects to birds, reptiles, amphibians, 

mammals and plants. The EPA makes a No Effects (NE) determination for all Federallylisted species and a No Habitat Modification determination for all designated critical 

habitats for the currently registered uses of Morpel®.
Page 18 of 21 

Appendix A: E-FAST v.2.0 Model Output 

INITIAL REVIEW EXPOSURE REPORT 

CHEMICAL ID: tmpcas 

ENVIRONMENTAL RELEASES OF CHEMICALS IN HOUSEHOLD PRODUCTS 

SCENARIO #: 1 EXPOSED POPULATION:Adult 

WWT 

REMOVAL 

(%) 

PRODUCTION 

VOLUME 

(kg/yr) 

HOUSEHOLD

RELEASE 

DAYS 

PRETREATMENT 

RELEASE 

(g/person/day) 

POSTTREATMENT 

RELEASE 

(g/person/day) 

BODY 

WEIGHT 

(kg) 

BCF 

(L/kg) 

14.72 898.00 365.00 8.46E-06 7.21E-06 71.80 105.30 

 

10th PERCENTILE DRINKING WATER AND FISH INGESTION EXPOSURE ESTIMATES 

Exposure 

Units 

Drinking 

Water 

Results 

Fish 

Ingestion 

Results

ASSUMPTIONS 

ED 

(years) 

AT 

(years) 

DW IR 

(L/day) 

FISH IR 

 (g/day) 

Cancer 

LADDpot 3.47E-08 mg/kg/day 1.56E-08 mg/kg/day 57.00 75.00 1.40 6.00 

LADCpot 1.78E-06 mg/L 1.87E-04 mg/kg 57.00 75.00 NA NA 

Acute 

ADRpot 8.63E-07 mg/kg/day 1.95E-06 mg/kg/day NA 1 day 6.00 129.00 

 

 
Page 19 of 21 

50th PERCENTILE DRINKING WATER AND FISH INGESTION EXPOSURE ESTIMATES 

Exposure 

Units 

Drinking 

Water 

Results 

Fish 

Ingestion 

Results

ASSUMPTIONS 

ED 

(years) 

AT 

(years) 

DW IR 

(L/day) 

FISH IR 

 (g/day) 

Cancer 

LADDpot 2.04E-09 mg/kg/day 9.22E-10 mg/kg/day 57.00 75.00 1.40 6.00 

LADCpot 1.05E-07 mg/L 1.10E-05 mg/kg 57.00 75.00 NA NA 

Acute 

ADRpot 3.92E-08 mg/kg/day 8.87E-08 mg/kg/day NA 1 day 6.00 129.00 

 

50th PERCENTILE AQUATIC EXPOSURE ESTIMATES - SURFACE WATER 

DESCRIPTOR Harmonic Mean 30Q5 7Q10 1Q10 

STREAM DILUTION 

FACTOR 

134.85 39.66 24.22 20.08 

CONCENTRATION (μg/L) 1.38E-04 4.69E-04 7.68E-04 9.26E-04 

10th PERCENTILE AQUATIC EXPOSURE ESTIMATES - SURFACE WATER 

DESCRIPTOR Harmonic Mean 30Q5 7Q10 1Q10 

STREAM DILUTION 

FACTOR 

7.95 1.80 1.00 1.00 

CONCENTRATION (μg/L) 2.34E-03 1.03E-02 1.86E-02 1.86E-02 
Page 20 of 21 

Appendix B: ECOSAR Model Output 

ECOSAR Version 1.11 Results Page 

 

SMILES : c1(C(=O)(OCCC))ccc(C(=O)(OCCC))nc1 

CHEM : 

CAS Num: 

ChemID1: 

MOL FOR: C13 H17 N1 O4 

MOL WT : 251.28 

Log Kow: 2.124 (EPISuite Kowwin v1.68 Estimate) 

Log Kow: (User Entered) 

Log Kow: 3.57 (PhysProp DB exp value - for comparison only) 

Melt Pt: (User Entered for Wat Sol estimate) 

Melt Pt: (deg C, PhysProp DB exp value for Wat Sol estimate) 

Wat Sol: 20.8 (mg/L, EPISuite WSKowwin v1.43 Estimate) 

Wat Sol: (User Entered) 

Wat Sol: (PhysProp DB exp value) 

 -------------------------------------- 

Values used to Generate ECOSAR Profile 

-------------------------------------- 

Log Kow: 2.124 (EPISuite Kowwin v1.68 Estimate) 

Wat Sol: 20.8 (mg/L, EPISuite WSKowwin v1.43 Estimate) 

 ------------------------------------------------ 

Available Measured Data from ECOSAR Training Set 

No Data Available 

ECOSAR v1.1 Class-specific Estimations-------------------------------------- 

Esters 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== 

========== 

Esters : Fish 96-hr LC50 28.435 * 

Esters : Daphnid 48-hr LC50 58.329 * 

Esters : Green Algae 96-hr EC50 24.342 * 

Esters : Fish ChV 2.084 

Esters : Daphnid ChV 38.485 * 

Esters : Green Algae ChV 6.49 

Esters : Fish (SW) 96-hr LC50 42.929 * 

Esters : Mysid 96-hr LC50 39.721 * 

Esters : Fish (SW) ChV 6.293 

Esters : Mysid (SW) ChV 2270.193 * 

Esters : Earthworm 14-day LC50 2988.053 * 

=========================== ================== ======== ====== 

========== 
Page 21 of 21 

Neutral Organic SAR : Fish 96-hr LC50 159.735 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 91.743 * 

 : Green Algae 96-hr EC50 71.653 * 

 : Fish ChV 15.826 

 : Daphnid ChV 9.237 

 : Green Algae ChV 19.249 

 Note: * = asterisk designates: Chemical may not be soluble enough to 

 measure this predicted effect. If the effect level exceeds the 

 water solubility by 10X, typically no effects at saturation (NES) 

 are reported. 

 

 

------------------------------ 

Class Specific LogKow Cut-Offs 

------------------------------ 

If the log Kow of the chemical is greater than the endpoint specific cut-offs 

presented below, then no effects at saturation are expected for those endpoints. 

 

Esters: 

------ 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50, Mysid LC50) 

Maximum LogKow: 6.0 (Earthworm LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV)