• 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

MEMORANDUM Date: August 2, 2012 

Subject: 

To: 

From: 

Approved: 

Registration Review -Ecological Risk, Environmental Fate, and Endangered 

Species Assessment for N,N-diethyl-meta-toluamide (DEET) 

PC Code: 080301 

DP Barcode: D399065 

Susan Bartow, Chemical Review Manager 

Anne Overstreet, Team Leader 

Risk Management and Implementation Branch IV 

Pesticide Re-evaluation Division (PRD) 

Christine Hartless, Ph.D., Wildlife Biologist 

James Lin, Ph.D., Environmental Engineer 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

Jean 

Brian 

Holmes, 

Anderson, 

RAPL 

Branch Chief 

~ )'l ( 1 ~ n 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

The Environmental Fate and Effects Division (EFED) has completed the ecological effect, 

environmental fate, and endangered species risk assessment to be conducted as part of the 

registration review of the insect repellant, N,N-diethyl-meta-toluamide (DEET). An evaluation 

of environmental risk to aquatic and terrestrial organisms as a result of the use of DEET is 

summarized in the Executive Summary and the Risk Characterization sections of the attached 

document. A separate document containing a problem formulation was not prepared for DEET; 

the problem formulation is contained within this risk assessment. At the present time, there are 

no identified data needs for the currently registered uses ofDEET as an insect repellant. 

There are no aquatic LOC exceedances based on low environmental exposure relative to DEET's 

toxicity to aquatic organisms. There are also no terrestrial risk concerns based on lack of a 

complete exposure pathway. In addition to effects on non-listed species, an assessment for 

effects on listed species was also prepared. No direct or indirect effects for any taxonomic groups 

and no habitat modifications were identified for labeled uses ofDEET. 

Page 1 of 41 
Page 2 of 41 

 

Environmental Fate and Ecological Risk Assessment 

for the Registration 

Review of 

N,N-diethyl-m-toluamide (DEET) 

N,N-diethyl-m-toluamide (DEET) (CAS 134-62-3) 

Prepared by:

Christine Hartless, Ph.D., Wildlife Biologist 

James Lin, Ph.D., Environmental Engineer 

U. S. Environmental Protection Agency 

Office of Pesticide Programs 

Environmental Fate and Effects Division

Environmental Risk Branch IV 

1200 Pennsylvania Ave., NW 

Mail Code 7507P 

Washington, DC 20460

Reviewed by: 

Jean Holmes, RAPL 

Brian Anderson, Branch Chief
Page 3 of 41 

Table of Contents 

1. Executive Summary ................................................................................................................ 4

1.1. Nature of Chemical Stressor ............................................................................................ 4

1.2. Potential Risks to Non-target Organisms ......................................................................... 4

1.3. Conclusions - Exposure Characterization ........................................................................ 5

1.4. Conclusions - Effects Characterization ............................................................................ 6

2. Problem Formulation .............................................................................................................. 6

2.1 Conclusions from Previous Risk Assessments................................................................. 6

2.2. Nature of Regulatory Action ............................................................................................ 7

2.3. Stressor Source and Distribution ...................................................................................... 7

2.4. Conceptual Model ............................................................................................................ 9

2.5. Analysis Plan .................................................................................................................. 11

2.6. Endangered Species Assessment .................................................................................... 15

2.7. Endocrine Disruptor Screening Program ....................................................................... 15

3. Analysis.............................................................................................................................. 16

3.1. Exposure Characterization ............................................................................................. 16

3.2. Ecological Effects Characterization ............................................................................... 20

4. Risk Characterization ............................................................................................................ 23

4.1. Risk Estimation .............................................................................................................. 23

4.2. Risk Description ............................................................................................................. 25

4.3. Uncertainties and Data Gaps .......................................................................................... 25

5. Federally Threatened and Endangered (Listed) Species Concerns ....................................... 26

5.1. Action Area .................................................................................................................... 27

5.2. Taxonomic Groups Potentially at Risk .......................................................................... 27

6. References ................................................................................................................................ 29

Appendix A: Environmental Fate and Ecotoxicity Data Requirement Tables ............................. 31

Appendix B: Publically Available Data Table from EPA’s ECOTOX Database ....................... 35

Appendix C: Ecological Incident Reports ................................................................................... 39

 
Page 4 of 41 

1. Executive Summary 

 1.1. Nature of Chemical Stressor 

Registration review is being performed for the insect repellent N,N-diethyl-m-toluamide (DEET, 

CAS Registry Number 134-62-3, PC Code 080301). This document contains the problem 

formulation as well as the environmental fate, ecological risk, and endangered species 

assessments for its registered uses. This risk assessment is intended to identify ecological risks 

associated with the registered uses of DEET as an insect and tick repellent. In addition to the 

repellent registrations, DEET has several industrial uses, as both a resin solvent and as a surface 

plasticizer (Holsten and Neely 1993). These industrial uses will not be evaluated in this risk 

assessment.

DEET is a broad spectrum insect and tick repellent used on the human body and clothing (skin, hair, 

clothing, footwear, shoes, and headgear (caps)) as well as on horses (body treatment). DEET is used 

to repel biting flies, biting midges, black flies, chiggers, deer flies, fleas, gnats, horse flies, 

mosquitoes, no-see-ums, sand flies, stable flies, and ticks. DEET was registered in the United States 

in 1957 for use by the general public after first being developed by the U.S. Army in 1946 for use by 

military personnel in insect-infested areas (USEPA, 1998b). DEET is not registered for any 

agricultural, non-agricultural, or greenhouse applications. It is also not registered for any home, 

residential, or indoor applications in which the chemical is applied to surfaces other than human skin 

and hair, currently worn clothing, footwear, and headgear, or horse skin. 

Currently, DEET is formulated as a microencapsulated, pressurized spray (aerosol), as impregnated 

materials (e.g. towelettes, roll-on), and as a ready-to-use solution (non aerosol pump spray, liquid, 

cream, lotion, or foam). DEET concentrations in end-use products range from 5.0 to 98.25% a.i. 

1.2. Potential Risks to Non-target Organisms 

The results of this assessment on currently registered DEET uses indicate that there are no LOC 

exceedances to listed or non-listed non-target organisms (Table 1.1). Additionally, the Agency 

has determined that there is no habitat modification of any designated critical habitat for listed 

species from the current registered uses of DEET. 

Conclusions regarding aquatic organisms 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; EFED 

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

of DEET and the large margin of safety observed for other aquatic taxonomic groups. In 

addition, no aquatic incidents have been reported. Conclusions regarding terrestrial organisms 

and plants are based on the lack of a complete exposure pathway. Exposure in terrestrial habitats 

would be limited to human skin, clothing, and shoes, as well as horse 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, clothing, and shoes, as well as horse skin and hair). 
Page 5 of 41 

Exposure to listed species is not expected because they would not likely come in close contact 

with humans or domestic horses (i.e., the registered use sites). Even if a non-target organism 

were to come into contact with DEET from over-spray, exposure levels would be expected to be 

low; therefore, given its low toxicity profile, effects to non-target organisms would not be 

anticipated to exceed concern levels even if exposure occurred. 

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

Indirect Effects from the Currently Registered Uses of DEET. 

Listed Taxon Direct Effects Indirect Effects 

Terrestrial and semi-aquatic plants - monocots No No

Terrestrial and semi-aquatic plants - dicots No No

Birds No No

Terrestrial-phase amphibians and reptiles No No

Mammals No No

Terrestrial invertebrates No No 

Aquatic nonvascular plants No No

Aquatic vascular plants No No

Freshwater fish No No

Aquatic-phase amphibians No No

Freshwater invertebrates No No

Marine/estuarine fish No No

Marine/estuarine invertebrates No No

 1.3. Conclusions - Exposure Characterization 

DEET is expected to be moderately mobile in the soil column. In surface waters and soil, DEET 

is expected to degrade at a moderate to rapid rate (its half-life is measured in days to weeks). 

The small amounts of DEET retained in air are subject to rapid photo-oxidation via hydroxy 

radical-mediated degradation with an estimated half-life between 10 to 15 hours. The 

bioaccumulation potential of DEET is low; it is neither a persistent, bioaccumulative toxicant nor 

a persistent organic pollutant. 

Aquatic exposure estimates for DEET are based on washoff after application to skin or clothing 

or to horses. Exposure estimates ranged from 0.005 to 0.42 mg a.i./L depending on the number 

of individuals entering a 20,000,000 L water body (standard farm pond). Surface water 

monitoring data based on multiple studies indicated a median of 0.046 μg a.i./L, and a 

90th percentile of 0.4 μg a.i./L (Aronson et al., 2011). 

Exposure to terrestrial non-target organisms and plants is expected to be inconsequential based 

on the labeled use patterns. 
Page 6 of 41 

 1.4. Conclusions - Effects Characterization 

Aquatic Organisms 

Technical grade DEET is classified as slightly toxic to fish, aquatic-phase amphibians, and 

aquatic invertebrates on an acute exposure basis. Toxicity data were not available for evaluation 

of DEET chronic exposure to freshwater fish and invertebrates. No toxicity data were available 

for estuarine/marine fish and invertebrates or for vascular and non-vascular aquatic plants. 

Terrestrial Organisms 

DEET is slightly toxic to birds on an acute oral exposure basis and is practically non-toxic to 

mammals on an acute oral exposure basis. No dietary or chronic toxicity data were available for 

birds. A two-generation laboratory rat study resulted in an offspring NOAEC = 500 mg/kg-diet 

based on decreased body weight in female pups; no frank reproductive effects were identified for 

parental survival, growth or reproduction. No toxicity data were available for non-target insects 

or terrestrial plants. 

2. Problem Formulation 

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

ecological risk assessment for the registration review risk assessment for the insect repellant, 

DEET. The problem formulation sets the objectives for the risk assessment, establishes a risk 

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

data and characterizing the risk associated with the uses of DEET (USEPA, 1998b). 

2.1 Conclusions from Previous Risk Assessments 

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

Eligibility Document (RED, signed April 1998) stated that: 

“Environmental risk assessments are not conducted for pesticides with 

exclusively indoor use patterns. N,N-diethyl-m-toluamide (DEET) is considered 

to be an "indoor residential" use rather than an outdoor use because it is only 

applied directly to the human body/clothing, cats, dogs, pet quarters, and 

household/domestic dwellings. Application of DEET to these sites is not likely to 

adversely affect terrestrial wildlife or aquatic organisms. 

A limited set of toxicity data for indoor-use pesticides is required to determine 

precautionary label statements and to assess environmental hazards in case of 

spills. The available data characterize DEET as slightly toxic to birds, fish, and 

aquatic invertebrates and as practically nontoxic to mammals.” 
Page 7 of 41 

2.2. Nature of Regulatory Action 

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

Insecticide, Fungicide, and Rodenticide Act (FIFRA) to ensure that the currently registered 

pesticide DEET is re-evaluated for potential to cause any unreasonable adverse effects to the 

environment. In addition potential effects to listed species (i.e., species on the Federal list of 

endangered and threatened wildlife and plants) and their designated critical habitat are also 

considered under the Endangered Species Act (ESA) in order to ensure that the continued 

registration of DEET is not likely to jeopardize the continued existence of listed species or 

adversely modify their critical habitat. In order to meet the requirements of FIFRA and the ESA, 

this assessment follows EPA guidance on conducting ecological risk assessments (USEPA, 

1998a). 

The end result of the EPA pesticide registration review process (i.e., the FIFRA regulatory 

action) is a set of approved product labels. The label is a legal document that stipulates how and 

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

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

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

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

was prepared to support evaluation of the registration review of DEET as an insect repellant; 

industrial uses of DEET will not be evaluated in this risk assessment.

2.3. Stressor Source and Distribution 

 2.3.1. Nature of Chemical Stressor 

DEET belongs to the chemical class of N,N-dialkylamides. The specific mechanism of action of 

DEET has not been determined. Early research concluded that DEET interfered with receptors in 

mosquito (and other biting insects) antennae that detect L-lactic acid and carbon dioxide, the 

primary attractants emitted by humans and other animals. Insects exposed to DEET are thereby 

unable to effectively locate a host (Davis et al., 1976; McIver et al., 1981; Snow, 1970). Later 

research indicated that DEET had a repellant effect on mosquitos with carbon dioxide as the only 

attractant, thus demonstrating that an interaction between DEET and lactic acid was not 

necessary to repel mosquitoes (Boeckh, et al., 1996; Hoffmann and Miller, 2003). Recent 

mosquito behavior research suggests that repellency is due to direct detection of vapor phase 

DEET by the olfactory receptor neurons (ORNs) in the antenna (Syed and Leil, 2008). Bohbot 

and Dickens (2010) reported that DEET has both excitatory and inhibitory properties on odorant 

receptors (ORs) resulting in the scrambling of cognitive olfactory inputs and ultimately 

behavioral disruption. 

2.3.2. Overview of Pesticide Usage 

It has been previously estimated that approximately 30% of the U.S. population uses DEET on 

their body and/or clothing annually as an insect and tick repellent (USEPA 1998b). Based on 

current DEET registration and use information, there are a total of 123 active registrations, 108 

are DEET only and 15 are co-formulated with both MGK 326 (insecticide, PC Code 047201) and 
Page 8 of 41 

MGK 264 (synergist, PC code 057001). Ten end-use products contain a sunscreen in addition to 

DEET. Percent a.i. in the ready-to-use products ranges from 5 to 98.25%. There is only one 

product registered for horse use, DEET Plus Composite Insect Spray II (packaged in 4 oz can 

with 17.5% a.i.). The approved pests associated with DEET uses are: biting flies, black flies, 

chiggers, deer flies, fleas, gnats, mosquitoes, stable fly, ticks, no-see-ums, biting insects, biting 

midges, greenhead flies, horse flies, mites, punkies, and sand flies. Application of DEET insect 

repellents to the skin and clothing can help prevent bites from mosquitoes, ticks and other vectors 

that may transmit diseases such as Lyme disease, West Nile virus, malaria, yellow fever, dengue 

fever, and encephalitis.

The physical forms of the registered products include: ready-to-use solution, pressurized liquid, 

impregnated materials, emulsifiable concentrate, soluble concentrate, microencapsulated, 

technical chemical and formulation intermediate. The approved use sites are human skin, human 

face area, human neck area, human clothing, human clothing footwear, human clothing 

headgear, shoes and horses. Uses supported at the time of the 1998 RED but that are no longer 

on current labels are households/domestic dwellings, cats (adults/kittens), dogs/canines 

(adults/puppies), and pet living/sleeping quarters. 

The following list provides representative directions for DEET end-use products: 

 Sun Skeeter (Illinois Tool Works, Inc.) (reg# 11694-112: 20% ai). Remove towelette 

and unfold fully. For maximum protection, wipe evenly and completely over all exposed 

skin. Avoid overexposure; frequent reapplication and saturation are unnecessary. Use 

just enough Sun Skeeter to cover exposed skin. After returning indoors, wash treated skin 

with soap and water or bathe. Remove and wash treated clothing before wearing it again.

 CUTTER Original Insect Repellent Pump Spray Formula MMI (Spectrum, United 

Industries) (reg# 121-34: 23% ai). For outdoor use only. Do not spray in enclosed 

areas. Hold bottle 6 - 8 inches from skin and clothing while spraying, keeping sprayer 

pointed away from face. Slightly moisten skin. Use just enough repellent to cover 

exposed skin and/or clothing. Do not use under clothing. For maximum protection on 

skin, spread with hand after application. For extra protection from ticks, chiggers and 

fleas, spray along all openings of clothing, such as neckband, waistband, pant and sleeve 

cuffs, sock tops and other areas where insects may crawl under clothing. Frequent 

reapplication or saturation is unnecessary· Avoid over-application of this product. After 

returning indoors, wash treated skin with soap and water. Wash treated clothing before 

wearing it again. 

 REPEL 15 (United Industries Corp.) (reg# 305-48: 15% ai). Hold container 6 to 8 

inches from skin or clothing and spray with a slow sweeping motion. Do not spray in 

enclosed areas. Use just enough repellent to cover exposed skin and/or clothing. Do not 

use under clothing. Avoid over-application. Works on clothing too: Spray shirts, pants, 

and hats. For ticks, chiggers and fleas apply to tops of socks and around openings of outer 

clothing. After returning indoors, wash treated skin with soap and water. Wash treated 

clothing before wearing it again. 

 Maximum Strength Pump Spray Deep Woods OFF! (S. C. Johnson & Son) (reg# 

4822-276: 98.25% ai). Hold container upright 4 to 6 inches away from skin or clothing. 

Use just enough repellent to cover exposed skin and/or clothing. Avoid over-application 

of this product. Frequent reapplication and saturation are unnecessary. Spray shirts, pants, 
Page 9 of 41 

socks, and hats. For ticks and chiggers also spray cuffs, socks and around other openings 

in outer clothing. 

 CUTTER Maximum Strength Insect Repellent Formula 100 (Spectrum, United 

Industries) (reg# 121-25: 98.11% ai). For outdoor use only. Do not use in enclosed 

areas. To apply, put a few drops in palm of hand, rub palms together, then spread evenly 

over exposed skin. Use just enough repellent to cover exposed skin and/or clothing. Do 

not use under clothing. For extra protection from ticks, chiggers and fleas, apply along all 

openings of clothing, such as neck-band, waistband, pant and sleeve cuffs, sock tops and 

other areas where insects may crawl under clothing. Frequent reapplication is 

unnecessary. Avoid over-application of this product. After returning indoors, wash 

treated skin with soap and water. Wash treated clothing before wearing it again.

 CCL Quick Breaking Insect Repellent Foam (K-G Spray-Pak) (reg# 46813-46: 

8.89% ai). Shake can well. Spray foam into palms of your hands and spread evenly on 

exposed areas of skin such as legs, arms, body, neck and face. Use just enough repellent 

to cover exposed skin and/or clothing. Avoid over-application of this product. After 

returning indoors, wash treated skin with soap and water. Wash treated clothing before 

wearing it again.

2.4. 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. 

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

predicted relationships between DEET, potential routes of exposure, and the predicted effects for 

the assessment endpoint. A conceptual model consists of two major components: risk hypothesis 

and a conceptual diagram (USEPA 1998a). 

2.4.1. Risk Hypotheses 

For the DEET national-level ecological risk assessment, the following ecological risk hypotheses 

are being employed: 

1) DEET, when used in accordance with current labels, can result in off-site 

movement of the compound via washoff by treated individuals entering water 

bodies as well as from showering/bathing and laundry leading to exposure of 

non-target aquatic plants and animals including federally-listed threatened 

and endangered species. 

2) Direct applications of DEET to human skin, clothing, and horse skin are not 

expected to result in significant exposure to non-target terrestrial plants and 

animals including federally-listed threatened and endangered species. 
Page 10 of 41 

 2.4.2. Conceptual Diagram 

The transport mechanism (washoff from treated individuals by swimming, bathing, and laundry) 

that may result in the movement of DEET into aquatic (water and sediment) habitats is depicted 

in the conceptual model below (Figure 2.1). Based on the use characteristics and environmental 

fate properties of DEET, runoff, spray drift, leaching, and atmospheric deposition are unlikely to 

result in aquatic or terrestrial exposures to non-target plants and organisms. For DEET, the only 

potential exposure pathway is washoff from skin and clothing when treated individuals enter 

recreational water bodies or treated individuals bathe themselves or launder clothing. 

Exposure in terrestrial habitats would be limited to human skin, clothing, and shoes, as well as 

horse 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, clothing, and shoes, as well 

as 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) and the potential attribute changes, i.e., effects such as reduced survival, 

growth and reproduction, in the receptors due to DEET exposure. The amount of DEET resulting 

from human or horse application in the terrestrial environment (air, ground, plants, or non-treated 

animals) is inconsequential. As there is no complete exposure pathway, a conceptual diagram for 

terrestrial exposure and effects was not included in this assessment. 

 

 
Page 11 of 41 

Figure 2.1. Conceptual model for DEET effects on aquatic organisms. 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk.

 

2.5. 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 DEET are characterized and 

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

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

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

quantitative estimate of likelihood and/or magnitude of an adverse effect. The likelihood of 

effects to individual organisms from particular uses of DEET is estimated using the probit doseresponse slope and either the level of concern (discussed below) or actual calculated risk quotient 

value. 

Stressor 

Source

Receptors 

Attribute 

Change 

DEET applied to use site (humans or horses) 

Spray drift 

Fish/aquatic-phase 

amphibians 

Eggs 

Larvae 

Juveniles / Adults 

Individual organisms 

Reduced survival 

Reduced growth 

Reduced reproduction 

Food chain 

Reduction in algae 

Reduction in prey 

Habitat integrity 

Reduction in primary productivity

Reduced cover 

Community change 

Surface water/ 

Sediment 

Runoff 

Aquatic Animals 

Invertebrates 

Vertebrates 

Exposure 

Media 

Uptake/gills 

or integument 

Ingestion Ingestion

Soil Groundwater 

Uptake/gills 

or integument 

Aquatic Plants 

Non-vascular 

Vascular 

Uptake/cell, 

roots, leaves

Washoff Atmosphere
Page 12 of 41 

2.5.1. Residues of Concern 

The parent compound, DEET, is the toxicant that will be assessed. Toxicity of DEET isomers 

and degradates will be assumed to be equivalent to parent compound in the absence of data to 

suggest otherwise. 

 2.5.2. Evaluation of Multiple Active Ingredients, Mixtures and Formulated 

Products 

The Agency does not routinely include in its risk assessments an evaluation of mixtures of active 

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

in the applicator’s tank. In the case of the product formulations of active ingredients (that is, a 

registered product containing more than one active ingredient), each active ingredient is subject 

to an individual risk assessment for regulatory decision regarding the active ingredient on a 

particular use site. If effects data are available for a formulated product containing more than 

one active ingredient, they may be used qualitatively or quantitatively. 

2.5.3. Measures of Exposure 

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

to identify specific ecosystems during the development of a nation-wide ecological risk 

assessment. 

Aquatic ecosystems potentially at risk from DEET exposure include water bodies adjacent to, or 

downstream from, the water bodies that were entered by treated humans or horses. In order to 

estimate risks of DEET exposures in aquatic environments, all exposure modeling and resulting 

risk conclusions will be based on maximum application rates and methods. Measures of aquatic 

exposure are typically based on models that predict estimated environmental concentrations 

(EECs) of DEET such the Pesticide Root Zone Model coupled with the Exposure Analysis 

Modeling System (PRZM/EXAMS). Because of the limited application methods (directly to 

human skin, clothing, shoes, and horse skin), the typical models used for exposure estimation 

will not be used in this assessment. It was assumed that DEET reaches surface water by 

application to humans or horses and the treated individuals enter the water body, and the applied 

DEET is then presumed to wash off the treated humans or horses and remain in the water 

column. Water concentrations in the standard pond will be calculated under the assumption of 10 

treated adults, 100 treated adults, 50 cans of product, or 10 treated horses entering the water body 

on a single day. Given the small size of the modeled water body, 10 and 100 swimming adults 

represent low and moderate aquatic exposures. Application of the equivalent of 50 cans of 

product represents a highly unlikely, very conservative aquatic exposure scenario, as it is not 

expected that such a large number of treated individuals would enter a single 1–hectare water 

body within a 24 hr period. The scenario is presented as a convenient measure to evaluate the 

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

DEET application to ten horses that enter a water body also represents a high exposure scenario 

for the horse use pattern. 
Page 13 of 41 

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

ecosystems potentially at risk could include the area in which treatment (application to human or 

horse) occurred. Exposure to non-target terrestrial organisms and plants is presumed negligible 

(Section 2.4.2) and will not be estimated. 

 2.5.4. Measures of Effect 

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

conducted with a limited number of surrogate test species (Table 2.1). 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 on DEET were located, based on a May 2012 query of the open literature in the 

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

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

potential risks of DEET to non-target organisms. Assessment endpoints represent the actual 

environmental value that is to be protected, defined by an ecological entity (species, community, 

or other entity) and its attribute or characteristics (USEPA, 1998a). The attributes for each of 

these entities may include growth, survival, and reproduction. 
Page 14 of 41 

Table 2.1. Measures of Exposure and Measures of Effect Used in Assessing Potential Risks 

Associated with the Registered Uses of DEET.

Assessment Endpoint Surrogate Species and Measures of 

Ecological Effect1 Measures of Exposure 

Aquatic Animals 

(Freshwater fish and 

invertebrates)2 

Survival Lowest tested LC50 or EC50

(acute toxicity test) 

estimated aquatic 

concentrations after 

treated individuals entered 

water body 

Reproduction 

and Growth 

No data 

Not calculated as no acute 

LOC exceedances and no 

chronic toxicity data 

available 

Aquatic Animals 

(Estuarine/marine fish 

and invertebrates)2 

Survival No data 

Presumed concentrations 

in water equal or less than 

those estimated for small 

freshwater pond 

Reproduction 

and Growth 

No data 

Not calculated as no acute 

LOC exceedances and no 

chronic toxicity data 

available 

Aquatic plants Growth No data 

estimated aquatic 

concentrations after 

treated individuals entered 

water body 

Birds3

Survival 

Lowest acute LD50 (single oral dose test) 

No LC50 (dietary exposure) data available 

Not calculated as no 

exposure expected 

Reproduction 

and Growth 

No data 

Mammals 

Survival Lowest acute LD50 (single oral dose test)

Reproduction 

and Growth 

Lowest NOAEC for frank reproductive effects 

(2-generation reproduction test) 

Insects Survival No data Not calculated as no 

exposure expected 

Terrestrial plants Survival and 

growth No data Not calculated as no exposure expected 

1 The most sensitive species tested within taxonomic groups is used for screening-level risk assessments. 2 Freshwater fish are considered surrogates for aquatic-phase amphibians. 3

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

 

 2.5.6. Integration of Exposure and Effects 

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

effects on non-target species. For the screening-level risk assessment of DEET, the deterministic 

risk quotient (RQ) method is used to compare estimated exposure concentrations with measured 

toxicity values. The RQ method involves dividing point estimates of environmental 

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

compared to the Agency’s Levels of Concern (LOC) (Table 2.2). These criteria are used to 

indicate when applications of DEET, as directed on the proposed labels, have the potential to 

cause adverse effects to listed and non-listed non-target organisms. 
Page 15 of 41 

Table 2.2. 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. 

2.6. Endangered Species Assessment 

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

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

registered uses of DEET. 

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

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

indicated by the exceedance of Agency LOCs used to evaluate direct or indirect effects. The 

action area is defined using the results of the risk assessment to establish boundaries for that 

action area with the understanding that exposures below the Agency’s defined LOCs constitute a 

no-effect threshold. For the purposes of this assessment, attention will be focused on the 

footprint of the action (i.e., the area where DEET application occurs), plus all areas where offsite 

transport may result in potential exposure that exceeds the Agency’s LOCs. Specific measures 

of ecological effect that define the action area for listed species include any direct and indirect 

effects and/or potential modification of its critical habitat, including reduction in survival, 

growth, and reproduction as well as the full suite of sub-lethal effects available in the effects 

literature. Therefore, the action area extends to a point where environmental exposures are below 

any measured lethal or sub-lethal effect threshold for any biological entity at the whole 

organism, organ, tissue, and/or cellular level of organization. In situations where it is not 

possible to determine the threshold for an observed effect, the action area is not spatially limited 

and is assumed to be the entire United States. The action area for DEET will be determined in 

Section 5.1. 

2.7. Endocrine Disruptor Screening Program 

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide active 

and other ingredients) may have an effect in humans or wildlife similar to an effect produced by 

a “naturally occurring estrogen, or other such endocrine effects as the Administrator may 
Page 16 of 41 

designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, and or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

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

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

 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first 

group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors. 

DEET is not among the group of 58 pesticide active ingredients receiving EDSP test orders. For 

information on the status of the orders issued under the EDSP for each chemical, please visit our 

website at http://www.epa.gov/endo/ and click on the "Status of EDSP Orders/DCIs" in the 

Highlights Box. Additional information on the EDSP, including the policies and procedures, the 

list of 67 chemicals, the test guidelines and the Tier 1 screening battery, can also be found at this 

website. 

3. Analysis 

3.1. Exposure Characterization 

3.1.1. Environmental Fate and Transport Characterization 

DEET is an all-purpose insect repellent which contains a minimum of 95% of the meta isomer, 

the most effective form of diethyl toluamide, as a technical ingredient. The technical DEET is a 

nearly colorless liquid with a faint characteristic odor. It is relatively stable, highly hygroscopic 

and sensitive to light. It is practically insoluble in glycerin but miscible with several organic 

solvents. 

The physicochemical characteristics associated with DEET are summarized in Table 3.1; the 

parameter values are from Weeks, et al. (2011). 

 
Page 17 of 41 

Table 3.1. Physicochemical properties of DEET 

Parameter Value Method 

Molecular formula C12H17NO 

Molecular weight 191.3 g/mol calculated 

Density 1.01 kg/L @ 20o

 C 

1.02 to 0.998 kg/L @ 20o

 C 

OECD 109 

ISO 1183, Method 3 

Water solubility 2072mg/L@ 20o

 C 

11200 mg/L @ 25o

C 

OECD 105 

EPA 830.7840 

Vapor pressure 0.00013 mm Hg @ 25°C 

0.017 Pa @ 25°C 

OECD 104 

EPA 830.7950 

Henry’s law constant 3.4 x 10-8 atm-m3/mol calculated 

Octanol-water partition coefficient 

(log Kow) 

2.02 

2.4 

OECD 107 

EPA 830.7570 

Bioconcentration factor (BCF) in fish 22 L/kg 

13.3 L/kg 

Regression w/ log Kow 

EPISuite v4.10 

Soil sorption coefficient (Koc) 47 to 126 L/kg 

43.3 L/kg 

OECD 106 (5 soils) 

OECD 121 

The only environmental fate study submitted to the Agency is the hydrolysis study (MRID 

40192701). The study demonstrated that DEET is stable to hydrolysis in solutions initially 

buffered to pH 5, 7, and 9. It can be concluded that DEET will be stable to hydrolysis at pH 

levels found in the environment. 

Based on the information from Weeks et al. (2011) presented in Table 3.1, DEET is expected to 

be moderately mobile in the soil column. In surface waters and soil, DEET is expected to 

degrade at a moderate to rapid rate (its half-life is measured in days to weeks). The small 

amounts of DEET retained in air are subject to rapid photo-oxidation via hydroxy radicalmediated degradation with an estimated half-life between 10 to 15 hours. The bioaccumulation 

potential of DEET is low; it is neither a persistent, bioaccumulative toxicant nor a persistent 

organic pollutant according to European Union (EU) regulatory PBT criteria (KemI 2010; Weeks 

et al. 2012). 

3.1.2. Estimated Surface Water Concentrations of DEET 

In order to estimate risks of DEET exposures in aquatic environments, all exposure modeling 

and resulting risk conclusions will be based on maximum application rates and methods. 

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

concentrations (EECs) of DEET such the Pesticide Root Zone Model coupled with the Exposure 

Analysis Modeling System (PRZM/EXAMS). Because use is restricted to direct application to 

human skin, clothing, shoes, and horse skin, the typical models used for exposure estimation will 

not be used in this assessment. 

Aquatic exposure could be expected via two routes: (1) washoff from treated skin and clothing 

when people or horses enter water bodies and (2) washoff from treated skin and clothing when 

people bathe or launder clothing. EFED estimated DEET water concentrations after people or 

horses entered a water body using the approach detailed below. DEET “down-the-drain” water 
Page 18 of 41 

concentrations (result of bathing and laundry) could be estimated using the EPA E-FAST model 

(http://www.epa.gov/oppt/exposure/pubs/efast.htm). Monitoring data indicated that DEET may 

be present in effluent (Section 3.1.3); however, the aquatic exposure assessment methods 

utilized for exposure from treated humans and horses swimming in water bodies are expected to 

account for peak and high-end EECs and would be protective of any potential “down-the-drain” 

exposure. 

Two end-use products for humans containing the highest quantity of DEET in single sale 

containers and the end-use product registered for use on horses will be evaluated for potential 

aquatic exposure. Super Guard Insect Repellant (EPA Reg. No. 54287-2) is 98.11% a.i. and sold 

in a 6 oz ready-to-use solution pump spray. PIC X-100% DEET (EPA Reg. No. 30950-27) is 

98.11% a.i. and sold in a 6 oz ready-to-use pressurized liquid-aerosol spray. Since the density of 

DEET is 0.996 g/l, fluid ounces are approximately equal to ounces as a unit of weight. Therefore, 

both 6 oz packages contain approximately 167,000 mg DEET. The only end-use product 

registered for use on horses is DEET Plus Composite Insect Spray II (EPA Reg. No. 54287-13, 

17.5% a.i.), and it will also be evaluated. 

The standard scenarios used for ecological pesticide assessments assume application to a 10-

hectare agricultural field that drains into an adjacent 1-hectare water body that is 2 meters deep 

(20,000 m3 volume equivalent to 20,000,000 L) with no outlet. PRZM/EXAMS is typically used 

to estimate screening-level exposure of aquatic organisms through runoff and drift. In this 

assessment, it was assumed that DEET reaches surface water by application to humans or horses 

and the treated individuals enter the water body. The applied DEET is then presumed to wash off 

the treated humans or horses and then remain in the water column. Water concentrations in the 

standard pond will be calculated under the assumption of 10 treated adults, 100 treated adults, 50 

cans of product, or 10 treated horses entering the water body on a single day. Given the small 

size of the modeled water body, 10 and 100 swimming adults represent a range of possible 

exposure scenarios, although an assumption of 100 swimming adults is conservative. 

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

conservative aquatic exposure scenario, as it is not expected that such a large number of treated 

individuals would enter a single 1–hectare water body within a 24 hr period. DEET application 

to ten horses also represents a high exposure scenario for the horse use pattern. 

The Standard Operating Procedures for Residential Pesticide Exposure Assessment developed by 

the Health Effects Division (HED) provide methods for assessment of pesticide exposures 

unrelated to employment or dietary intake of food or water (USEPA, 2012). Exposure 

assessment methods in this document include scenarios reflecting individuals who purchase 

pesticides and complete their own applications, such as adult and child application rate 

calculations for insect repellants. Of the different available application methods and 

concentrations of DEET in the individual products, pump sprays and aerosol sprays provide the 

highest application rates per individual. HED’s methodology determines an applied dose (mg 

a.i./kg-day) as well as an absorbed dose (mg a.i./kg-day); however for the purposes of this 

aquatic exposure estimation, the applied dose will be used and converted to a total daily dose per 

individual using an average adult body weight of 80 kg: 

 
Page 19 of 41 

D = ARF * FAI * ET * AppF * SA/BW * FBody * BW

where: 

D = dose (mg/individual-day); 

ARF = formulation-specific application rate (mg product/cm2

 skin); 

FAI = product-specific fraction of active ingredient (mg ai/mg product); 

ET = exposure time (hours/day); 

AppF = application frequency (applications/hour); 

SA/BW = total body surface area to body weight ratio (cm2

/kg); 

FBody = clothing-dependent fraction of body exposed (fraction exposed/application); 

BW = 80 kilograms. 

For adult human applications, ARF, ET, AppF, SA/BW, FBody, and BW were determined using 

default values from HED’s SOP. For horses, the SA/BW and BW values were 100 cm2

/kg and 

500 kg, respectively (http://www.rd1.com/lifestyle/horse-articles/summer-feeding-strategies). 

Using the high concentrations of end-use products for humans (98% a.i.), adult individuals were 

treated with 9453 or 16771 mg a.i./day for pump and aerosol sprays, respectively (Table 3.2). 

Individual horses were treated with 3764 mg a.i./day assuming the same fraction coverage, 

application intervals, and exposure time as humans. 

Under the assumption that 10 adults, 100 adults, or 10 horses entered a 20,000,000 L waterbody 

and all the applied DEET washed off skin/hair/clothing and was instantaneously mixed into the 

waterbody, the resulting concentrations of DEET in the water ranged between 0.002 and 0.08 mg 

a.i./L (Table 3.3). If the equivalent of 50 containers of product (6 oz of 98% a.i.) were 

instantaneously mixed in the 20,000,000 L waterbody, the resulting DEET concentration was 

calculated to be 0.42 mg a.i./L. These scenarios result in conservative screening level exposure 

estimates for aquatic organisms. 

Table 3.2. Calculations for determining mg a.i./individual/day for DEET spray treatments.

Repellent 

without 

sunscreen 

Amount 

of ai in 

product 

(mg ai/mg 

product) 

Formulationspecific AR 

(mg 

product/cm2

skin) 

Fraction 

Body 

Exposed 

SA to BW 

Ratio 

(cm2/kg) 

Exposure 

Time 

(hr/day) 

Application 

Frequency 

(#/hr) 

Exposure 

(mg a.i./kgday)a

Exposure 

(mg a.i./ 

individual/ 

day)b 

Human 

(pump 

spray) 

0.98 0.62 0.75 280 3.7 0.25 118 9453 

Human 

(aerosol 

spray) 

0.98 1.10 0.75 280 3.7 0.25 210 16771 

Horse 

(pump 

spray) 

0.18 0.62 0.75 100 3.7 0.25 7.5 3764 

a

 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#sops for details). b

 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. 
Page 20 of 41 

Table 3.3. Aquatic exposure estimates of DEET (mg a.i./L) 

End-use product % a.i. Total application Total mg a.i. mg a.i./L in 

ponda 

SUPER GUARD INSECT 

REPELLENT 

(EPA Reg. No. 54287-2), 

pump spray 

98.11 

10 adults 94,530 0.005 

100 adults 945,300 0.05 

50 cans product 8,344,355 0.42 

PIC X-100% DEET 

(EPA Reg. No. 3095-27), 

aerosol spray 

98.11 

10 adults 167,710 0.008 

100 adults 1,677,100 0.08 

50 cans product 8,344,355 0.42 

DEET PLUS COMPOSITE 

INSECT SPRAY II 

(EPA Reg. No. 54287-13), 

aerosol spray 

17.5 10 treated horses 37,600b

 0.002 

a

 Pond volume of 20,000,000 L. 

b

 Calculated using same approach as for adult humans except surface area to body weight ratio was 100 

cm2/kg and body weight was 500 kg (http://www.rd1.com/lifestyle/horse-articles/summer-feedingstrategies). 

3.1.3. Surface Water Concentrations of DEET Based on Monitoring 

Available monitoring data is used to qualitatively characterize exposure and compare with 

modeling results. Surface water concentrations in the United States and elsewhere are reviewed 

and evaluated by Aronson et al. (2011). The distribution of DEET concentrations from multiple 

monitoring studies of wastewater effluents, and streams, and rivers was found to have a median 

of 0.046 μg/L and a 90th percentile of 0.4 μg/L. The expected concentrations across the United 

States depend on the geographical distribution of population, and the factors affecting dilution of 

DEET residues as they travel in wastewater. The locations of waste water treatment plants 

(WWTPs), their effluent volumes, population served, and the network of receiving streams are 

all known to a relatively good degree for the United States. These data are contained in 

databases made available by the USEPA and USGS. Aronson et al. (2011) used two publicly 

available modeling systems (E-FAST and iSTREAM) to predict the pattern of DEET 

concentrations expected throughout the United States. The results show that the known repellent 

use of DEET is consistent with the observed distribution of concentrations seen in monitoring 

studies. 

3.1.4. Estimates of Terrestrial Exposure to DEET 

Exposure to non-target terrestrial organisms and plants is presumed negligible (Section 2.4.2) 

and will not be estimated. 

3.2. Ecological Effects Characterization 

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

effects a pesticide can have on aquatic and terrestrial organisms. To date, toxicity tests for 
Page 21 of 41 

amphibian or reptiles are not required; birds are used as surrogates for reptiles and terrestrialphase amphibians and freshwater fish are used as surrogates for aquatic-phase amphibians. This 

characterization is based on the registrant-submitted toxicity data for birds, mammals, fish, and 

invertebrates. 

This assessment evaluates the potential for DEET to directly or indirectly affect listed species or 

modify designated critical habitat. As previously discussed in Section 2.5, assessment endpoints 

may include direct toxic effects on the survival, reproduction, and growth of listed entities, as 

well as indirect effects, such as reduction of the prey base or modification of habitat. In addition, 

potential modification of critical habitat is assessed by evaluating effects to the primary 

constituent elements (PCEs), which are components of the critical habitat areas that provide 

essential life cycle needs of listed entities. 

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 3.4 provides a summary of the taxonomic groups and the surrogate species tested to 

characterize the potential acute and chronic ecological effects of DEET. In addition, the table 

provides a preliminary overview of the potential acute toxicity of DEET by providing the acute 

toxicity classifications. 

Table 3.4. Test Species Evaluated for Assessing Potential Ecological Effects of DEET 

and the Associated Acute Toxicity Classification. 

Taxonomic Group Tested Species and 

Study Type Toxicity Endpoint 

Study MRID 

and Toxicity 

Classification 

Birds1

 Bobwhite quail 

(Colinus virginianus) 

(acute oral) 

LD50 = 1375 mg a.i./kg-bwt 41159701 

(acceptable) 

Slightly toxic 

 Avian dietary No data -- 

Avian reproduction No data -- 

Mammals 

Laboratory rat 

(Rattus norvegicus) 

(acute oral) 

LD50 = 3900 mg a.i./kg-bwt 

 41678101 

(acceptable3) 

Practically nontoxic 

Laboratory rat 

(2-generation) 

Offspring NOAEC = 500 ppm (NOAEL = 2.5 

mg/kg-bw) based on LOAEC of 2000 ppm for 

decreased body weight in female pups. 

No frank reproductive effects were identified 

for parental survival, growth or reproduction 

(i.e., parental and reproductive NOAEC = 

5000 ppm; NOAEL = 250 mg/kg-bw) 

40979001 

Insects Honey bee No data -- 

Freshwater fish2

Rainbow trout 

(Oncorhynchus 

mykiss)

LC50 = 75 mg a.i./L 

00001026 

(acceptable) 

Slightly toxic 

Freshwater 

invertebrates Daphnia magna EC50 = 75 mg a.i./L 

00243419 

(acceptable) 

Slightly toxic 
Page 22 of 41 

Table 3.4. Test Species Evaluated for Assessing Potential Ecological Effects of DEET 

and the Associated Acute Toxicity Classification. 

Taxonomic Group Tested Species and 

Study Type Toxicity Endpoint 

Study MRID 

and Toxicity 

Classification 

Estuarine/marine 

fish No data -- 

Estuarine/marine 

invertebrates No data -- 

Terrestrial plants No data -- 

Aquatic plants and 

algae No data -- 

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). 

3.2.1. Effects to Aquatic Organisms

Technical grade DEET is classified as slightly toxic to fish, aquatic-phase amphibians, and 

aquatic invertebrates on an acute exposure basis. Toxicity data were not available for evaluation 

of DEET chronic exposure to freshwater fish and invertebrates. No toxicity data were available 

for estuarine/marine fish and invertebrates or for vascular and non-vascular aquatic plants. 

3.2.2. Effects to Terrestrial Organisms

DEET is slightly toxic to birds on an acute oral exposure basis and is practically non-toxic to 

mammals on an acute oral exposure basis. No dietary or chronic toxicity data were available for 

birds. A two-generation laboratory rat study resulted in an offspring NOAEC = 500 ppm 

(NOAEL = 2.5 mg/kg-bw) based on LOAEC of 2000 ppm for decreased body weight in female 

pups and no frank reproductive effects were identified for parental survival, growth or 

reproduction (i.e., parental and reproductive NOAEC = 5000 ppm; NOAEL = 250 mg/kg-bw; 

MRID 40979001). 

No DEET toxicity data were available for bees, non-target insects, or terrestrial plants. Given the 

mode of action of DEET, it is likely that many terrestrial invertebrates would be repelled from 

exposures to DEET. 

3.2.4. Degradate toxicity 

Based on the only available submitted environmental fate study, DEET will be stable to 

hydrolysis at pH levels found in the environment. Therefore no degradates were identified in 

that study. The open literature identified the possible degradates including: 3-methylbenzoate 

and diethylamine. Given the lack of information on degradates, including their toxicity, 

degradates will be presumed to have the same toxicity as the parent. 

 
Page 23 of 41 

3.2.5. ECOTOX Open Literature 

Literature identified in the search of the publically available ECOTOX database resulted in 

several additional citations (Appendix B). The cited aquatic toxicity data did not provide 

endpoints that were more sensitive than the data that was submitted to the Agency. In addition, 

none of the aquatic data filled existing data gaps (e.g., chronic toxicity, estuarine/marine fish and 

invertebrate toxicity). 

The cited terrestrial toxicity data did not either provide endpoints that were more sensitive than 

endpoints of submitted studies or fill existing data gaps for birds, mammals, or plants. One study 

evaluating the toxicity of DEET to mites was identified in the publically available ECOTOX 

database; however, no studies on non-target insects were available. 

Jeong et al. (2008) (ECOTOX# 102656) evaluated the toxicity of Thymus vulgaris oil, its main 

components, DEET, and benzyl benzoate, to the Tryophagus putrencentiae, as stored food mite. 

A fabric disk bioassay (test material was dissolved in acetone and applied to disks of black 

cotton fabric) was used. Treated fabric was placed in a petri dish (covering the bottom), mites 

were added, and a lid was placed on top. Treated and control mites were held in the dark for 24 

hours; mortality was then assessed. The resulting LD50 for DEET was 13.7 μg/cm2

 with a 95% 

confidence interval of (13.1, 14.7). The exposure intensity and duration experienced by the mites 

in this study is not comparable to the potential exposures based on currently registered uses of 

DEET. 

4. Risk Characterization 

4.1. Risk Estimation 

Toxicity data and exposure estimates are used to evaluate the potential for adverse ecological 

effects on non-target species. This assessment for DEET relies on the deterministic RQ method 

to provide a metric of potential risks. The RQ provides a comparison of exposure estimates to 

toxicity endpoints (i.e., the estimated exposure concentrations are divided by acute and chronic 

toxicity values). The resulting unitless RQs are compared to the Agency’s LOCs, as shown in 

Table 2.3. LOCs are used by the Agency to indicate when the use of a pesticide, as directed by 

the label, has the potential to cause adverse effects to non-target organisms. 

 

 4.1.1. Aquatic Organisms 

The screening-level aquatic EECs based on the application rates for highest concentration 

products for human use and the only product registered for horse use. The exposure estimates, 

representing concentrations in surface water, and toxicity data were used to calculate RQs (Table 

4.1). The expected concentrations of DEET in the aquatic environment are several orders of 

magnitude lower than the available aquatic LC50 and EC50s determined for DEET, and thus the 

potential for adverse risks is low. 

 
Page 24 of 41 

Table 4.1. Aquatic exposure estimates and RQs for DEET 

End-use product % a.i. Total application mg a.i./L in pond RQ for fish and 

invertebrates1,2 

SUPER GUARD INSECT 

REPELLENT (EPA Reg. No. 

54287-2), pump spray

98.11 

10 adults 0.005 0.00007 

100 adults 0.05 0.0007 

50 cans product 0.42 0.006 

PIC X-100% DEET (EPA Reg. 

No. 3095-27), aerosol spray 98.11 

10 adults 0.008 0.0002 

100 adults 0.08 0.002 

50 cans product 0.42 0.006 

DEET PLUS COMPOSITE 

INSECT SPRAY II (EPA Reg. 

No. 54287-13), aerosol spray 

17.5 10 treated horses 0.002 0.00003 

1

 LC50 for rainbow trout and EC50 for daphids = 75 mg a.i./L; therefore, calculated RQs will be identical. 2

 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

4.1.2. Incident Database Review 

A review of the following databases was completed on May 29, 2012: 

 Ecological Incident Information System (EIIS), 

 ‘Aggregate Incident Reports’ database, 

 Avian Monitoring Information System (AIMS, 

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

 Contaminant Exposure and Effects – Terrestrial Vertebrate (CEE-TV, 

http://www.pwrc.usgs.gov/contaminants-online/pages/CEETV/CEETVintro.htm). 

Incident reports are attached in Appendix C. One incident was listed in the EIIS database and 

one incident was listed in the Aggregate Incident Report database. No additional incidents for 

DEET were identified in the AIMS or the CEE-TV databases. 

One wildlife incident was reported in the EIIS database (I024160-001). A juvenile, female 

screech owl was brought to the Wildlife Disease Laboratory in East Lansing, Michigan, on 

November 10, 2003. The necropsy report indicated the bird was in good physical condition with 

the exception of blood-tinged mucoid material subcutaneously on the flank and lower back areas. 

The ventriculus contents (one beetle and non-descript food material) were analyzed for toxicants 

and a positive result was reported for DEET. The measured DEET concentration and the level of 

detection were not reported based on the GC/MS screen, and the list of other chemicals included 

in the screen was not provided. The written description of “blood-tinged mucoid material” may 

suggest hemorrhaging due to anticoagulants, but the report does not state that anticoagulants 

were included in the toxicity screen conducted on the screech owl. Chemicals, including 

anticoagulants, which have been detected by this laboratory are provided at the following link 

(http://www.animalhealth.msu.edu/sections/toxicology/WEBCD.TOX.REF.001.pdf). The 

necropsy report concluded with a diagnosis of “Poisoning, Deet (Possible).” The legality of the 

use (i.e., registered use or misuse) is unknown. EFED believes that the toxicological properties 

of the chemical and the low exposure potential based on registered uses suggest that it is unlikely 

that legal use of DEET caused the mortality of this screech owl. 

One minor wildlife incident for DEET (specific product not reported) was identified in the 

Aggregate Incident Report database was reported to have occurred between July 1, 2002, and 
Page 25 of 41 

September 30, 2002, by the registrant, SC Johnson (I013475-56). No information regarding 

species, number of individuals, geographic region, habitat, likelihood of exposure, etc., was 

included in the report. Because of the lack of information, the EPA cannot assess the likelihood 

that DEET was indeed the cause of the alleged adverse effect to wildlife. Based on the low 

toxicity and limited exposure potential of DEET, as well as the limited information provided in 

the aggregate report, this reported incident is not adequate to demonstrate the potential for risk to 

wildlife from registered DEET use. 

4.2. Risk Description 

4.2.1 Exposure and Risk to Aquatic Organisms 

The results of risk estimation indicate that registered uses of DEET will not result in LOC 

exceedances for acute risk to fish and invertebrates. Chronic RQs were not calculated; however, 

given the large margin of safety observed for acute effects based on the most conservative 

exposure scenario, it is unlikely that chronic RQs would approach concern levels. 

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 mode of action of DEET 

and the large margin of safety demonstrated for other aquatic organisms. Also, there are no 

reported incidents for aquatic organisms or plants. 

4.2.2 Risks to Terrestrial Organisms 

Exposure in terrestrial habitats would be limited to human skin, clothing, and shoes, as well as 

horse 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, clothing, and shoes, as well 

as 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) and the potential attribute changes, i.e., effects such as reduced survival, 

growth and reproduction, in the receptors due to DEET exposure. The amount of DEET resulting 

from human or horse application in the terrestrial environment (air, ground, plants, or non-treated 

animals) is inconsequential. As there is no complete exposure pathway under the currently 

registered uses, EFED presumed risk was discountable to terrestrial organisms. 

4.3. Uncertainties and Data Gaps 

With only one acceptable hydrolysis study submitted to the Agency, there are many data gaps for 

fate and transport parameters. However, the available open literature and monitoring data 

suggest DEET does exist in aquatic environments (especially the wastewater streams) with low 

concentrations. The calculated exposures based on washoff from treated humans and horses into 

a pond and the monitoring data suggest that potential aquatic exposures are several orders of 

magnitude less than levels of concern. 
Page 26 of 41 

Few ecotoxicity studies have been submitted to the Agency, and there are many data gaps for the 

effects data. However, under the currently registered use patterns, EFED has concluded (1) low 

likelihood of risk to aquatic organisms (2) no complete exposure pathway for non-target 

terrestrial organisms. 

Unless the use patterns of DEET change through proposed registrations of new labels, EFED 

does not consider that filling any of these data gaps is necessary at this time. 

5. Federally Threatened and Endangered (Listed) Species 

Concerns 

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2), requires all federal 

agencies to consult with the National Marine Fisheries Service (NMFS) for marine and 

anadromous listed species, and/or the United States Fish and Wildlife Service (USFWS) for 

listed wildlife and freshwater organisms, if they are proposing an "action" that may affect listed 

species or their designated critical habitat. Each federal agency is required under the Act to 

ensure that any action they authorize, fund, or carry out is not likely to jeopardize the continued 

existence of a listed species or result in the destruction or adverse modification of designated 

critical habitat. To jeopardize the continued existence of a listed species means "to engage in an 

action that reasonably would be expected, directly or indirectly, to reduce appreciably the 

likelihood of both the survival and recovery of a listed species in the wild by reducing the 

reproduction, numbers, or distribution of the species" (50 C.F.R. § 402.02). 

To facilitate compliance with the requirements of the Endangered Species Act (subsection 

(a)(2)), the Office of Pesticide Programs has established procedures to evaluate whether a 

proposed registration action may directly or indirectly appreciably reduce the likelihood of both 

the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, 

or distribution of any listed species. After the Agency’s screening level risk assessment is 

conducted, if any of the Agency’s listed species’ LOCs are exceeded for either direct or indirect 

effects, an analysis is conducted to determine if any listed or candidate species may co-occur in 

the area of the proposed pesticide use or areas downstream or downwind that could be 

contaminated from drift or runoff/erosion. If listed or candidate species may be present in the 

proposed action area, further biological assessment is undertaken. The extent to which listed 

species may be at risk is considered, which then determines the need for the development of a 

more comprehensive consultation package, as required by the Endangered Species Act. 

The federal action addressed herein is the proposed registration renewal of DEET for human and 

horse use and it is expected that the use could occur nationwide. 
Page 27 of 41 

5.1. Action Area 

For listed species assessment purposes, the action area is considered to be the area affected 

directly or indirectly by DEET use and not merely the immediate area where DEET is applied. 

At the initial baseline, the risk assessment considers broadly described taxonomic groups and 

conservatively assumes that listed species within those broad groups are co-located with the 

pesticide treatment area. This means that listed terrestrial plants and wildlife are assumed to be 

located on or adjacent to the treated site and listed aquatic organisms are assumed to be located 

in a surface water body adjacent to the treated site. The assessment also assumes that the listed 

species are located within an assumed area, which has the relatively highest potential exposure to 

the pesticide, and that exposures are likely to decrease with distance from the treatment area. 

Sections 2.3.2 and 3.1 of this risk assessment present the proposed pesticide use sites that are 

used to establish initial co-location of species with treatment areas. An action area is defined as 

the spatial extent where effects may occur; therefore, no action area is defined for this risk 

assessment because no LOCs were exceeded. As there is no defined action area, a “no effect” 

determination is made for all listed species.

5.2. Taxonomic Groups Potentially at Risk 

 

If RQs are below the listed species LOCs, a "no effect" determination conclusion is made with 

respect to listed species in that taxon, and no further refinement of the action area is necessary. 

Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no 

concern for indirect effects on listed species that depend upon the taxonomic group for which the 

RQ was calculated. However, in situations where the screening assumptions lead to RQs in 

excess of the listed species LOCs for a given taxonomic group, a potential for a "may affect" 

conclusion exists and may be associated with direct effects on listed species belonging to that 

taxonomic group or may extend to indirect effects upon listed species that depend upon that 

taxonomic group as a resource. In such cases, additional information on the biology of listed 

species, the locations of these species, and the locations of use sites are considered to determine 

the extent to which screening assumptions regarding an action area apply to a particular listed 

organism. These subsequent refinement steps will consider how this information would impact 

the action area for a particular listed organism and potentially include areas of exposure that are 

downwind and downstream of the pesticide use site. 

Assessment endpoints, exposure pathways, and the conceptual models addressing existing DEET 

uses, and the associated exposure and effects analyses conducted for the DEET baseline risk 

assessment are in Sections 2 to 3. The assessment endpoints used in the baseline risk assessment 

include those defined operationally as reduced survival for aquatic animal species from direct 

acute exposures. These assessment endpoints are intended to address the standard set forth in the 

Endangered Species Act requiring federal agencies to ensure that any action they authorize does 

not appreciably reduce the likelihood of both the survival and recovery of a listed species in the 

wild by reducing the reproduction, numbers, or distribution of the species. Risk estimates (RQs) 

which, integrating exposure and effects, are calculated for broad based taxonomic groups in the 

screening-level risk assessment presented in Section 4.
Page 28 of 41 

Both acute endangered species and chronic risk LOCs are considered in the baseline risk 

assessment to identify direct and indirect effects to taxa of listed species. This section identifies 

direct effect concerns, by taxa that are triggered by exceeding endangered LOCs in the baseline 

risk assessment, with an evaluation of the potential of individual effects for exposures that may 

occur at the established endangered species LOC. Data on exposure and effects collected under 

field and laboratory conditions are evaluated to make determinations on the predictive utility of 

the direct effect screening assessment findings to listed species. 

For the uses of DEET, risk from acute exposure is not expected for any non-target animals or 

plants (Table 5.1). Additionally, the Agency has determined that there will be no habitat 

modification of any designated critical habitat for listed species from the current registered uses 

of DEET. Inference regarding aquatic organisms and plants are based on the risk conclusions 

that registered uses of DEET will not result in LOC exceedances for acute risk to fish and 

invertebrates. 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 mode of 

action of DEET, the large margin of safety observed for other aquatic organisms, and the lack of 

any reported incidents. Similarly, no chronic data were available to allow for chronic RQ 

calculations. However, given the large margin of safety observed for acute effects based on the 

most conservative exposure scenario, chronic RQs are unlikely to exceed concern levels. 

Conclusions regarding terrestrial organisms and plants are based on the lack of a complete 

exposure pathway. Exposure in terrestrial habitats would be limited to human skin, clothing, and 

shoes, as well as horse 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, clothing, and 

shoes, as well as horse skin and hair). Exposure to listed species is not expected because they 

would not likely come in close contact with humans or domestic horses (i.e., the registered use 

sites). 

Table 5.1. Potential Effects to Federally Listed Taxa Associated with Direct or Indirect 

Effects from the Currently Registered Uses of DEET. 

Listed Taxon Direct Effects Indirect Effects 

Terrestrial and semi-aquatic plants - monocots No No

Terrestrial and semi-aquatic plants - dicots No No

Birds No No

Terrestrial-phase amphibians and reptiles No No

Mammals No No

Terrestrial invertebrates No No

Aquatic nonvascular plants No No

Aquatic vascular plants No No

Freshwater fish No No

Aquatic-phase amphibians No No

Freshwater invertebrates No No

Marine/estuarine fish No No

Marine/estuarine invertebrates No No
Page 29 of 41 

6. References 

Aronson D., J Weeks, B Meylan, P Guiney, and P H Howard. 2011. Environmental Release, 

Environmental Concentrations, and Ecological Risk of N,N-Diethyl-m-Toluamide (DEET). 

Integrated Environmental Assessment and Management. Volume 8, Number 1: p135-166. 

Boeckh J, et al. (1996) Acylated 1,3-aminopropanols as repellents against bloodsucking 

arthropods. Pestic Sci 48:359–373. 

Bohbot JD, Dickens JC (2010) Insect Repellents: Modulators of Mosquito Odorant Receptor 

Activity. PLoS ONE 5(8): e12138. doi:10.1371/journal.pone.0012138 

Davis, E. E.; Sokolove, P. G. Lactic Acid-sensitive Receptors on the Antennae of the Mosquito, 

Aedes aegypti. J. Comp. Physiol. 1976, 105, 43-54. 

Hoffmann EJ, Miller JR (2003) Reassessment of the role and utility of wind in suppression of 

mosquito (Diptera: Culicidae) host finding: Stimulus dilution supported over flight limitation. J 

Med Entomol 40:607–614 

Holsten JR, Neely NE. 1993. Method for dyeing aromatic polyamide fibrous materials: N,Ndiethyl(meta-toluamide) dye carrier. Washington (DC): US Patent Office. Patent 5207803. 

[accessed 2012 May 29]. Available from: http://www.freepatentsonline.com/5207803.html

Jeong, E.Y., J.H. Lim, H.G. Kim, and H.S. Lee. 2008. Acaricidal Activity of Thymus vulgaris

Oil and Its Main Components Against Tyrophagus putrescentiae, a Stored Food Mite. J. Food 

Prot.71(2): 351-355 ECOTOX Ref. No. 102656 

KemI. 2010. Assessment report, N,N-diethyl-meta-toluamide (DEET), Product-type 19 

(repellents and attractants). Sundbyberg (SE): KemI, Swedish Chemicals Agency, Rapporteur 

Member State. 11 March 2010. [cited 2011 May 25]. Available from: 

http://www.kemi.se/default____550.aspx

McIver, S. B. A model for the mechanism of action of the repellent DEET on the Aedes Aegypti 

(Diptera: Culicidae). J. Med. Entomol. 1981, 18 (5), 357-361. 

Snow, W. F. The effect of a reduction in expired carbon dioxide on the attractiveness of human 

subjects to mosquitoes. Bull. Ent. Res. 1970, 60, 43-48. 

Syed Z, Leal WS. 2008. Mosquitoes smell and avoid the insect repellent DEET. Proc Natl Acad 

Sci USA 105:13598–13603. 

USEPA, 1980. Pesticide Registration Standard - DEET. Registration Division and Special 

Pesticide Review Division, U.S. Environmental Protection Agency. Washington, D.C. NTIS No. 

PB81-207722. 

USEPA. 1998a. Guidelines for Ecological Risk Assessment. United States Environmental 
Page 30 of 41 

Protection Agency (USEPA). Risk Assessment Forum. Office of Research and Development. 

Available at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12460 (Accessed June 19, 

2009). 

USEPA. 1998b. EPA Reregistration Eligibility Decision (RED). United States Environmental 

Protection Agency, Washington DC 20460. http://www.epa.gov/oppsrrdlIREDs/0002red.pdf

USEPA 2012. Standard Operating Procedures for Residential Pesticide Exposure Assessment. 

U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics, Office of 

Pesticide Programs, Health Effects Division. Washington DC. 

http://www.epa.gov/pesticides/science/residential-exposure-sop.html

USFWS/NMFS/NOAA.2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act 

Section 7 Consultation Regulations; Final Rule. Federal Register Volume 69. Number 20. Pages 

47731-47762. August 5, 2004. 

Weeks J, Guiney P, Nikiforov A. 2012. Assessment of the environmental fate and ecotoxicity of 

N,N-diethyl-m-toluamide (DEET). Integr Environ Assess Manag 8:118–132.

 
Page 31 of 41 

Appendix A: Environmental Fate and Ecotoxicity Data 

Requirement Tables 
Page 32 of 41 

Table A-1. Available environmental fate data for DEET and remaining data gaps. 

158 Guideline 

(OPPTS) Description MRID Classification Data Gap? Comments 

835.1230 

(163-1) 

 Leaching No data No* 

835.1240 

(163-1) 

Adsorption/desorption No data No* 

 835.1410 

(163-2) 

Laboratory volatility No data No* 

 835.2120 

(161-1) 

Hydrolysis MRID 40192701 No 

 835.2240 

(161-2) 

Photodegradation in water No data No* 

835.2370 

(161-4) 

Photodegradation in air No data No* 

835.2410 

(161-3) 

Photodegradation on soil No data No* 

 835.4100 

(162-1) 

Aerobic soil metabolism No data No* 

835.4200 

(162-2) 

Anaerobic soil metabolism No data No* 

 835.4300 

(162-4) 

Aerobic aquatic metabolism No data No* 

 835.4400 

(162-3) 

Anaerobic aquatic 

metabolism 

No data No* 

 835.6100 

(164-1) 

Terrestrial field dissipation No data No* 

835.6200 

(164-2) 

Aquatic field dissipation No data No* 

835-6300 

(164-3) 

Forestry field dissipation No data No* 

850.1730 

(165-4) 

Fish bioconcentration factor No data No* 

NGS Drinking water treatment No data No* 

* Not identified as a data gap under currently registered uses. Proposal of new uses may change the data requirements. 
Page 33 of 41 

Table A-2. Available ecological effects data for terrestrial animals exposed to technical DEET and remaining 

data gaps. 

158 

Guideline 

(OPPTS) 

Description MRID/ 

Accession Classification Data Gap? Comments 

 850.2100 

(71-1) Avian oral toxicity MRID 41159701 Acceptable No 

. 

 850.2200 

(71-2) Avian dietary toxicity No data No* 

 850.2300 

(71-4) Avian reproduction No data No* 

 850.3020 

(141-1) 

Honeybee acute contact 

toxicity 

No data 

 No* 

 850.3040 

(141-5) 

Field testing for 

pollinators 

No data 

 No* 

* Not identified as a data gap under currently registered uses. Proposal of new uses may change the data requirements. 

Table A-3. Available ecological effects data for aquatic animals exposed to technical DEET and remaining 

data gaps. 

Guideline Description MRID/ 

Accession 

Classification Data Gap? Comments 

 850.1075 

(72-1) 

Freshwater fish – 

acute toxicity 

Acc. 

00001026 Acceptable No 

 850.1075 

(72-3) 

Saltwater fish – 

acute toxicity 

No data 

 No* 

 850.1010 

(72-2) 

Freshwater invertebrates – 

acute toxicity 

Acc. 

00243419 Acceptable No 

 850.1025 

s850.1035 

(72-3) 

Saltwater invertebrates – 

acute toxicity 

No data 

 No* 

 850.1300 

(72-4) 

Freshwater invertebrate – 

 life cycle test 

No data 

 No* 

 850.1350 

(72-4) 

Saltwater invertebrates – 

life cycle test 

No data 

 No* 

 850.1400 

(72-4) Freshwater fish – 

early life stage test 

No data 

 No* 

 850.1400 

(72-4) 

Saltwater fish – 

early life stage test 

No data 

 No* 

 850.1500 

(72-5) 

Fish – 

life cycle test 

No data No* 

* Not identified as a data gap under currently registered uses. Proposal of new uses may change the data requirements. 
Page 34 of 41 

Table A-4. Available ecological effects data for plants exposed to DEET and remaining data gaps. 

Guideline Description MRID Classification Data Gap? Comments 

 850.4100 

(122-1) 

Terrestrial plant toxicity: tier 

1 seedling emergence 

No data No*

 850.4225 

(123-1) 

Terrestrial plant toxicity: tier 

2 seedling emergence 

No data No*

 850.4150 

(122-1) 

Terrestrial plant toxicity: tier 

I vegetative vigor 

No data No*

 850.4150 

(123-1) 

Terrestrial plant toxicity: tier 

2 vegetative vigor 

No data No*

 850.4400 

(123-2) 

Aquatic plant growth: algae No data No* 

 850.4400 

(123-2) 

Aquatic plant growth: 

vascular plants 

No data No*

* Not identified as a data gap under currently registered uses. Proposal of new uses may change the data requirements. 

 
Page 35 of 41 

Appendix B: Publically Available Data Table from EPA’s 

ECOTOX Database 

 
Page 36 of 41 

Table B-1. Aquatic Ecotoxicity references provided in the publically available ECOTOX database. 

CAS Number 

Species Scientific Name 

Species Common Name Endpoint 

Conc 1 Mean Op (ug/L) 

Conc 1 Mean (ug/L) 

Conc 1 Units (ug/L) 

Reference Number Author Title Source 

134623 

Daphnia magna Water Flea EC50 75000 ug/L 344 

Office of Pesticide Programs 

Pesticide Ecotoxicity Database (Formerly: Environmental Effects Database (EEDB)) 

Environmental Fate and Effects DivisioU.S.EPA, Washington, D.C.: 

134623 

Gammarus fasciatus Scud LC50 > 100000 ug/L 6797 

Mayer,F.L.,Jr., and M.R. Ellersieck 

Manual of Acute Toxicity: Interpretation and Data Base for 410 Chemicals and 66 Species of Freshwater Animals 

Resour.Publ.No.16U.S.Dep.Interior, Fish Wildl.Serv., Washington, DC:50p. 

134623 

Gammarus fasciatus Scud LC50 > 100000 ug/L 6797 

Mayer,F.L.,Jr., and M.R. Ellersieck 

Manual of Acute Toxicity: Interpretation and Data Base for 410 Chemicals and 66 Species of Freshwater Animals 

Resour.Publ.No.16U.S.Dep.Interior, Fish Wildl.Serv., Washington, DC:50p. 

134623 

Gambusia affinis 

Western Mosquitofish LC50 235000 ug/L 944 

Michael,A.G., and G.S. Grant 

Toxicity of the Repellent DEET (N,N-DiethylMetatoluamide) to Gambusia affinis (Baird and Girard) 

Mosq. News34(1): 32-35 

134623 

Gambusia affinis 

Western Mosquitofish LC50 235000 ug/L 944 

Michael,A.G., and G.S. Grant 

Toxicity of the Repellent DEET (N,N-DiethylMetatoluamide) to Gambusia affinis (Baird and Girard) 

Mosq. News34(1): 32-35 
Page 37 of 41 

CAS Number 

Species Scientific Name 

Species Common Name Endpoint 

Conc 1 Mean Op (ug/L) 

Conc 1 Mean (ug/L) 

Conc 1 Units (ug/L) 

Reference Number Author Title Source 

134623 

Oncorhynchus mykiss 

Rainbow Trout LC50 71250 ug/L 344 

Office of Pesticide Programs 

Pesticide Ecotoxicity Database (Formerly: Environmental Effects Database (EEDB)) 

Environmental Fate and Effects DivisioU.S.EPA, Washington, D.C.: 

134623 

Pimephales promelas 

Fathead Minnow LC50 110000 ug/L 12448 

Brooke,L.T., D.J. Call, D.L. Geiger, and C.E. Northcott 

Acute Toxicities of Organic Chemicals to Fathead Minnows (Pimephales promelas), Vol. 1 

Center for Lake Superior Environmental Studies, University Wisconsin-SuperioSuperior, WI:414 p

134623 

Oreochromis mossambicus 

Mozambique Tilapia NR 120000 ug/L 3073 

Mathai,A.T., K.S. Pillai, and P.B. Deshmukh 

Acute Toxicity of Deet to a Freshwater Fish, Tilapia mossambica: Effect on Tissue Glutathione Levels 

J. Environ. Biol.10(2): 87-91 

134623 

Oreochromis mossambicus 

Mozambique Tilapia NR NR ug/L 3073 

Mathai,A.T., K.S. Pillai, and P.B. Deshmukh 

Acute Toxicity of Deet to a Freshwater Fish, Tilapia mossambica: Effect on Tissue Glutathione Levels 

J. Environ. Biol.10(2): 87-91 
Page 38 of 41 

Table B-2. Terrestrial Ecotoxicity references provided in the publically available ECOTOX database. 

CAS Number 

Species Group 

Species Scientific Name 

Species Common Name Endpoint 

Observed Response Mean 

Observed Response Units Effect 

Reference Number Source Author Title 

134623 Birds 

Colinus virginianus 

Northern Bobwhite Quail LD50 1375 

mg/kg org MOR 344 

Environmental Fate and Effects Division, U.S.EPA, Washington, D.C.: 

Office of Pesticide Programs 

Pesticide Ecotoxicity Database (Formerly: EnvironmeEffects Database (EEDB)) 

134623 Insects/Spiders 

Tyrophagus putrescentiae 

Copra Mite LD50 13.9 ug/cm2 MOR 102656 

J. Food Prot.71(2): 351-355 

Jeong,E.Y., J.H. Lim, H.G. Kim, and H.S. Lee 

Acaricidal Activity of Thymus vulgaris Oand Its MaComponenAgainst Tyrophaguputrescentia Stored FoMite 
Page 39 of 41 

Appendix C: Ecological Incident Reports 

 
Page 40 of 41 

 
Page 41 of 41