REGISTRATION REVIEW

ECOLOGICAL RISK ASSESSMENT AND EFFECTS 

DETERMINATION

Quizalofop-P-Ethyl

CAS Number 100646-51-3

USEPA PC CODE 128709 

ethyl (2R)-2-[4-[(6-chloro-2-quinoxalinyl)oxy]phenoxy]propanoate

Prepared by:

Meghan Radtke, Ph.D., Biologist

Stephen Wente, Ph.D., Biologist

Environmental Risk Branch I

Reviewed by:

Anita Ullagaddi, M.S., Biologist

Michael Lowit; Ph.D., Biologist

Environmental Risk Branch I

Environmental Fate and Effects Division

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460
iv

Executive Summary

Quizalofop-p-ethyl is the active ingredient in quizalofop-ethyl herbicides. “Quizalofopethyl” is commonly used to refer to a pesticide composed of a 50/50 racemic mixture of Rand S-enantiomers (PC 128711). “Quizalofop-p-ethyl” is used to refer to a pesticide 

composed almost exclusively of the R-enantiomer (PC 128709). The R- enantiomer is the 

isomer with pesticidal properties. Both isomers were first registered in 1988, but only 

quizalofop-p-ethyl (PC 128709) has current active registrations.

E.1 Nature of Stressor

Quizalofop-p-ethyl is a systemic herbicide for the control of annual and perennial grasses

that is registered for use on numerous crops such as cotton, soybeans, dry beans, lentils, 

sunflower, flax, wheat, and barley. Affected plant tissues become necrotic/chlorotic and die 

leaving treated plants stunted and non-competitive. Products are applied as liquid sprays 

(aerial and ground application equipment) and the timing corresponds with weed control at 

all stages of agricultural production (e.g., pre-emergence, during planting, post-emergence, 

pre-harvest, and burn down). Products are sold as emulsifiable concentrates and ready-to-use 

solutions that are 1.4% or 10.3% active ingredient.

Quizalofop-p-ethyl degrades into quizalofop acid (the actual active ingredient; sometimes 

referred to as “quizalofop”), a major degradate, which further degrades into 3-OH-quizalofop 

acid (another major degradate) and several minor degradates. The quizalofop-p-ethyl 

molecule is better able to penetrate the waxy cuticle of a leaf because of its relatively 

lipophilic nature, while quizalofop acid is better able to penetrate the cell wall and cell 

membrane because of its semi-lipophilic nature (less lipophilic, but not hydrophilic either). 

Quizalofop-p-ethyl, quizalofop acid, and 3-OH-quizalofop acid (because of its structural 

similarities to quizalofop acid) are considered the stressors for this risk assessment.

E.2 Assessment of Risk

Fate and effects data are largely available only for the parent chemical, quizalofop-p-ethyl. 

A total residues approach was used to adjust exposure half-lives to account for the duration 

of exposure to all three chemicals of concern. This issue affects the certainty of the risk 

conclusions.

E.2.1 Physico-Chemical and Environmental Fate Properties

Quizalofop-p-ethyl is relatively stable to hydrolysis at pHs of 5 and 7, but degrades much 

faster at pH 9 with a half life of 2 days. Quizalofop-p-ethyl is relatively stable to photolysis 

in water and soil (t1/2 > 40 days). Laboratory aerobic soil metabolism studies show that 

quizalofop-p-ethyl degrades with a half-life of ~30 days to quizalofop acid, 3-OH-quizalofop 
v

acid, and phenolic compounds. This compares with the terrestrial field dissipation (TFD) 

study producing quizalofop-p-ethyl half-lives of 1 to 12 days with quizalofop acid and 3-OHquizalofop acid as degradates. (Note that field dissipation encompasses more transport and 

degradation pathways than laboratory degradation studies.) Laboratory anaerobic aquatic 

metabolism studies indicate half-lives of 95 and 107 days. (No studies have been submitted 

for anaerobic soil and aerobic aquatic metabolism.) Based on available fate studies

conducted on the parent, quizalofop acid appears to be less persistent than the parent under 

aerobic conditions, but similar in mobility to the parent compound. As for mobility, the 

mean adsorption Koc of quizalofop acid is 256 ml/g, whereas the mean adsorption Koc value 

of quizalofop-p-ethyl is 298 (both classified as moderately mobile). No data are available for 

3-OH-quizalofop acid, but it is assumed to have properties similar to quizalofop acid, based 

on structural similarities.

E.2.2 Ecological Risk Conclusions

The specific taxa that may be at risk from quizalofop-p-ethyl are dependent on the specific 

registered quizalofop-p-ethyl use. In general, registered uses of quizalofop-p-ethyl may 

cause direct adverse effects to mammals (chronic) and terrestrial monocots. EECs from 

scenarios that indicated potential chronic risks to mammals were 1 to 4 times the value of the 

LOAEC. The pineapple use may cause direct adverse effects to freshwater fish (chronic –

EECs were half of the LOAEC and twice the NOAEC), freshwater invertebrates (acute), and 

estuarine/marine invertebrates (acute). It should be noted that the “paved area” scenario also 

indicated potential risk to aquatic organisms, but the scenario was very conservative because 

it assumed a spot treatment for weeds in paved areas would be applied over an entire acre. 

By assuming a more realistic percentage (treating 25% of an acre), risks were eliminated. 

Direct effects are not expected for other taxonomic groups. 

Given that there are possible direct effects to mammals, freshwater fish, aquatic 

invertebrates, and plants, indirect effects to other organisms could occur. Indirect effects 

could include changes to food, shelter, seed dispersal/pollination, or other alterations of 

habitat. 

A spray drift analysis indicated that risks to terrestrial monocots from ground applications of 

quizalofop-p-ethyl could be eliminated through the implementation of buffers (52 to 394 ft). 

These buffers only apply to risks from spray drift as a result of ground applications; risks to 

terrestrial monocots from runoff and/or aerial applications may be lessened through the use 

of these buffers, but not necessarily eliminated.

Tables E.1 – E.3 list the potential direct and indirect effects to listed and non-listed species, 

based on risk quotients exceeding the level of concern, as well as the organism group and 
vi

size classes potentially at risk from the highest application rate for each use of quizalofop-pethyl.

Table E.1. Potential direct effects to listed and non-listed terrestrial organisms from 

exposure to quizalofop-p-ethyl1

Quizalofop-p-ethyl Listed Terrestrial Species Non-listed Terrestrial Species

Birds2 Mammals Plants Birds2 Mammals Plants

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

ID, MT, WA, OR, 

WY, only

Non-food/non-feed 

seed production: 

alfalfa, carrot, Chinese 

cabbage, garlic, onion, 

radish, red beets, 

spinach, Swiss chard

N N N Y 

(S,M,L)

Y N N N Y 

(S,M,L)

Y

Except NY: barley, 

wheat

N N N Y (S,M) Y N N N Y (S,M) Y

Canola/rape, crambe, 

soybeans, sunflowers

N N N Y 

(S,M,L)

Y N N N Y 

(S,M,L)

Y

Field corn seed 

production (herbicidetolerant)

N N N Y (S,M) Y N N N Y (S,M) Y

Sorghum (herbicidetolerant)N N N Y 

(S,M,L)

Y N N N Y 

(S,M,L)

Y

Cotton N N N Y

(S,M)

Y N N N Y

(S,M)

Y

Dry beans N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

Dry and succulent 

peas, lentils, snap 

beans

N N N Y

(S,M)

Y N N N Y

(S,M)

Y

TX, OK, KS, CO, 

only: fallow

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

Flax, garbanzos 

(including chick peas)

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

ME, MN, only: hybrid 

cottonwood/ poplar 

plantations

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

Mint (spearmint and 

peppermint)

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

Non-crop areas N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

Puerto Rico only: 

pineapple

HI only: pineapple 

and ornamental and/or 

shade trees

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y
vii

Quizalofop-p-ethyl Listed Terrestrial Species Non-listed Terrestrial Species

Birds2 Mammals Plants Birds2 Mammals Plants

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Paved areas N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

MN only: perennial 

ryegrass grown for 

seed

N N N Y

(S,M,L)

Y N N N Y

(S,M,L)

Y

1 Y= Potential direct effects (RQ ≥ LOC); N = Potential direct effects not expected (RQ < LOC); S, M or L 

indicate which size class is potentially affected; S = small bird (20 g) or mammal (15 g); M = medium bird (100 

g) or mammal (35 g); L = large bird (1000 g) or mammal (1000 g). For mammals, chronic size classes are for 

dose-based exposure only. Dietary-based acute and chronic exposure for birds and mammals is not evaluated 

using body weights. RQ values were determined for these specific weights only, therefore, it is expected that 

potential direct effects may exist between two size classes in which the lower size class exceeded the LOC but 

the next size class did not. Therefore, for example, if small birds (20 g) exceeded the LOC but medium birds 

(100 g) did not, then potential direct effects may exist for all birds less than 100 g at any life stage until can be 

shown otherwise.

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

Table E.2. Potential direct effects to listed aquatic organisms from exposure to 

quizalofop-p-ethyl1

Quizalofop-p-ethyl

Freshwater Fish Estuarine/Marine 

Fish

Vascular 

Aquatic 

Plants

Freshwater 

Invertebrates

Estuarine/Marine 

Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

ID, MT, WA, OR, WY, 

only

Non-food/non-feed seed 

production: alfalfa, 

carrot, Chinese cabbage, 

garlic, onion, radish, red 

beets, spinach, Swiss 

chard

N N N N N N N N N

Except NY: barley, 

wheat

N N N N N N N N N

Canola/rape, crambe, 

soybeans, sunflowers

N N N N N N N N N

Field corn seed 

production (herbicidetolerant)

N N N N N N N N N

Sorghum (herbicidetolerant)

N N N N N N N N N
viii

Quizalofop-p-ethyl

Freshwater Fish Estuarine/Marine 

Fish

Vascular 

Aquatic 

Plants

Freshwater 

Invertebrates

Estuarine/Marine 

Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Cotton N N N N N N N N N

Dry beans N N N N N N N N N

Dry and succulent peas, 

lentils, snap beans

N N N N N N N N N

TX, OK, KS, CO, only: 

fallow

N N N N N N N N N

Flax, garbanzos 

(including chick peas)

N N N N N N N N N

ME, MN, only: hybrid 

cottonwood/ poplar 

plantations

N N N N N N N N N

Mint (spearmint and 

peppermint)

N N N N N N N N N

Non-crop areas N N N N N N N N N

Puerto Rico only: 

pineapple

HI only: pineapple and 

ornamental and/or shade 

trees

N Y N N N Y N Y N

Paved areas N N N N N N N N N

MN only: perennial 

ryegrass grown for seed

N N N N N N N N N

1 Y= Potential direct effects; N = Potential direct effects not expected

Table E.3. Potential direct effects to non-listed aquatic organisms from exposure to 

quizalofop-p-ethyl1

Quizalofop-p-ethyl

Freshwater Fish Estuarine/Marine 

Fish

Vascular 

Aquatic 

Plants

Freshwater 

Invertebrates

Estuarine/Marine 

Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic
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Quizalofop-p-ethyl

Freshwater Fish Estuarine/Marine 

Fish

Vascular 

Aquatic 

Plants

Freshwater 

Invertebrates

Estuarine/Marine 

Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

ID, MT, WA, OR, WY, 

only

Non-food/non-feed seed 

production: alfalfa, 

carrot, Chinese cabbage, 

garlic, onion, radish, red 

beets, spinach, Swiss 

chard

N N N N N N N N N

Except NY: barley, 

wheat

N N N N N N N N N

Canola/rape, crambe, 

soybeans, sunflowers

N N N N N N N N N

Field corn seed 

production (herbicidetolerant)

N N N N N N N N N

Sorghum (herbicidetolerant)

N N N N N N N N N

Cotton N N N N N N N N N

Dry beans N N N N N N N N N

Dry and succulent peas, 

lentils, snap beans

N N N N N N N N N

TX, OK, KS, CO, only: 

fallow

N N N N N N N N N

Flax, garbanzos 

(including chick peas)

N N N N N N N N N

ME, MN, only: hybrid 

cottonwood/ poplar 

plantations

N N N N N N N N N

Mint (spearmint and 

peppermint)

N N N N N N N N N

Non-crop areas N N N N N N N N N

Puerto Rico only: 

pineapple

HI only: pineapple and 

ornamental and/or shade 

trees

N Y N N N N N N N

Paved areas N N N N N N N N N

MN only: perennial 

ryegrass grown for seed

N N N N N N N N N

1 Y= Potential direct effects; N = Potential direct effects not expected

E.3 Uncertainties
x

Certain data and other supporting information were not available to the Agency as it 

conducted the preliminary risk assessment for quizalofop-p-ethyl. As such, certain 

assumptions were made and conclusions were based on the information that was available. 

For some taxa, this may have resulted in the use of overly conservative approaches for 

evaluating risk. EFED has identified the information it believes may help best resolve these 

uncertainties. Additional information may allow EFED to refine its risk conclusions for 

certain species. Below is a summary of the uncertainties associated with the risk assessment 

of quizalofop-p-ethyl.

E.3.1 Ecotoxicity Data Gaps and Uncertainties

There were several ecotoxicity endpoints for which data were not available or available data 

were non-definitive. 

Estuarine/Marine Fish (Acute) OPPTS 850.1075. In the Problem Formulation, data 

were not requested because a registrant study had recently been submitted for this 

endpoint. A detailed review of the study at a later date indicated that it was “invalid” 

and thus not useable for risk assessments. To compensate for this data gap, 

freshwater and estuarine/marine acute fish toxicity studies for two structurally similar 

chemicals (fenoxaprop-p-ethyl and fenoxaprop-ethyl) were reviewed. The 

fenoxaprop-ethyl data indicated that freshwater fish are more sensitive than 

estuarine/marine fish. A comparison of quizalofop-p-ethyl acute freshwater fish data 

to fenoxaprop-ethyl indicated that quizalofop-p-ethyl is more toxic than fenoxapropethyl. Thus it was determined that acute freshwater fish data from quizalofop-p-ethyl 

would be a protective surrogate for the missing estuarine/marine data. 

Estuarine/Marine Invertebrate (Chronic) OPPTS 850.1350. In the Problem 

Formulation, data were not requested because it was possible to calculate an acute-tochronic ratio using freshwater invertebrates (waterflea) as a surrogate. An acute-tochronic ratio will be used in the registration review risk assessment as well.

Freshwater Fish (Chronic) OPPTS 850.1400. Chronic data are available for the 

fathead minnow; however, the most sensitive acute freshwater fish endpoint is for the 

rainbow trout. Acute toxicity information is not available for the fathead minnow. 

To ensure that the most sensitive chronic endpoint for freshwater fish was employed 

in the risk assessment, the acute to chronic ratio methodology was applied. An acutechronic pair of data was available for the fathead minnow for fenoxaprop-p-ethyl, a 

structurally similar chemical to quizalofop-p-ethyl. The ratio between the 

fenoxaprop-p-ethyl fathead minnow endpoints was applied to the quizalofop-p-ethyl 

acute freshwater fish endpoint to derive a protective freshwater fish chronic endpoint.

Avian (Acute) (LD50) OPPTS 850.2100. Definitive data were not available for the 

LD50, and the NOAEL was reported as a “less than” value because effects were 

observed. EECs, based on the highest application rate, were less than one tenth of the 
xi

highest dose tested (2000 mg ai/kg-bw), indicating that more refined, definitive data 

were not necessary for this assessment.

Passerine Birds (Acute) (LD50) OPPTS 850.2100. Data were not available. At the 

time the Problem Formulation was written, passerine bird data were not required. In 

lieu of this endpoint, the acute oral toxicity of quizalofop-p-ethyl to the mallard duck 

and common quail was used to evaluate risk. 

Avian (Chronic) (NOAEC) OPPTS 850.2300. The mallard duck study presented a 

non-definitive (less than) NOAEC. Given that the NOAEC was a “less than” value it 

presents uncertainty as to the true NOAEC and cannot be used in the risk assessment 

to calculate risk quotients. Mallard duck data from two structurally similar chemicals 

(fenoxaprop-p-ethyl and fenoxaprop-ethyl) were considered as potential surrogates 

for the toxicity data. Fenoxaprop-ethyl yielded a NOAEC (180 mg ai/kg-diet) that 

was below the quizalofop-p-ethyl value (< 296 mg ai/kg-diet). Given the similarity 

between fenoxaprop and quizalofop, it was decided that the fenoxaprop-ethyl mallard 

duck NOAEC could be used in place of the non-definitive quizalofop-p-ethyl value. 

Aquatic Non-Vascular Plants (EC50) OPPTS 850.5400. Three of the four Tier 2 

studies for non-vascular plants were non-definitive (greater than); these were also the 

most sensitive toxicity values. To justify the use of a less sensitive endpoint, nonvascular studies from two structurally similar chemicals (fenoxaprop-p-ethyl and 

fenoxaprop-ethyl) were considered. These chemicals also presented non-definitive 

toxicity values at the lowest concentrations tested and definitive toxicity numbers at 

higher concentrations. In addition, the fenoxaprop toxicity values were within the 

same order of magnitude as the quizalofop values. Thus, it was determined that using 

the definitive quizalofop-p-ethyl toxicity value was a reasonable approach, given that 

the lower toxicity values were all “greater than” values.

E.3.2 Application Rates

Several labels did not include the seasonal and/or annual maximum application rate of 

quizalofop-p-ethyl. In these cases, seasonal maximum application rates were assumed based 

on other information from the label or similar application patterns for uses that did contain 

the complete information. The Biological and Economic Division (BEAD) of OPP was 

consulted for their expertise. The following scenarios were affected:

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, 

and other similar areas) – seasonal maximum application rate assumed to be 

equivalent to twice the maximum single application rate

Paved areas (private roads/sidewalks) – seasonal maximum application rate assumed 

to be equivalent to single maximum application rate

Hybrid cottonwood/poplar plantations – seasonal maximum application rate assumed 

to be equivalent to two applications at the single maximum application rate
xii

E.3.3 Fate Data Gaps

A quizalofop-p-ethyl hydrolysis study was submitted to address deficiencies in the 

previously submitted study. However, the second hydrolysis study was not performed under 

Agency guidelines (elevated temperature without quantification of degradates). Studies have 

not been provided for anaerobic soil and aerobic aquatic metabolism. Additionally, the 

parent fish bioconcentration study was not performed under conditions that allowed the fish 

to be continuously exposed to the parent compound. The highest BCF was seen in viscera in 

the first few days of the study, presumably when the parent had not yet degraded. As the test 

progressed, the BCFs declined. 

Few data are available for the degradates of concern. For quizalofop acid and 3-OHquizalofop acid, information is unavailable on aqueous and soil photolysis, aerobic and 

anaerobic soil metabolism, and aerobic and anaerobic aquatic metabolism (terrestrial field 

dissipation studies are typically not performed on degradates because these studies are based 

on formulated products). Additionally, hydrolysis and adsorption/desorption studies are not 

available for 3-OH-quizalofop acid.

E.3.4 Incomplete Life Histories of Listed Species

Currently, a database of life histories for each of the listed animals and plants is not available 

for use by EFED. These life histories would include information such as body size at each 

life stage, food sources, relationships with other taxa, habitat, and reproductive habits. As 

such, conservative (protective) assumptions were made concerning the potential relationships 

between species in that each species was assumed to have a relationship with the other taxa. 

This is assumed to be an overestimation of the actual species that have a species dependant 

relationship. 

E.3.5 Locations of Listed Species

In addition, the specific occurrences of listed species are not known in some cases beyond the 

county-level. If the location of a species was not known in greater detail than the county 

level, the species was assumed to occur anywhere within that county at any time. Likewise, 

crop location data are also uncertain. Crops may rotate every year and some spatial datasets 

combine several crop types, making it impossible to distinguish one crop from another. 

Further, timing may play a role in the location of species and whether it overlaps with the 

time that a particular crop is in a field. These assumptions may lead to an overestimation of 

co-occurrence with quizalofop-p-ethyl exposure and overestimation of the number of species 

potentially at risk.
xiii

Table of Contents

Introduction............................................................................................................................. 18

Purpose of Assessment........................................................................................................ 18

Problem Formulation........................................................................................................... 19

Previous Risk Assessments ............................................................................................. 20

Stressor Source and Distribution ..................................................................................... 20

Mechanism of Action and Side Effects .................................................................................. 20

Overview of Pesticide Use and Usage .................................................................................... 21

Environmental Fate and Transport .................................................................................. 29

Summary of Environmental Fate ............................................................................................ 29

Receptors......................................................................................................................... 33

Effects to Organisms............................................................................................................... 33

Incident Database Review....................................................................................................... 33

Data Gaps Identified ............................................................................................................... 34

Ecosystems Potentially at Risk ............................................................................................... 34

Conceptual Model............................................................................................................ 35

Risk Hypothesis............................................................................................................... 37

Analysis Plan ................................................................................................................... 37

Measures to Evaluate the Risk Hypothesis and Conceptual Model ....................................... 37

Measures of Effect .................................................................................................................. 38

Integration of Exposure and Effects ....................................................................................... 38

Analysis of Co-occurance of Federally Listed Species with Quizalofop-p-ethyl................... 39

Exposure Assessment.............................................................................................................. 40

Aquatic Exposure Assessment ............................................................................................ 40

Monitoring Data .................................................................................................................. 40

Aquatic Exposure Modeling................................................................................................ 40

TIER II PRZM/EXAMS Model.............................................................................................. 40

Aquatic Exposure Modeling Results................................................................................... 42

Terrestrial Exposure ............................................................................................................ 48

Dietary-Based Quizalofop-P-Ethyl Residue Levels........................................................ 48

Off-Field Terrestrial and Wetland/Riparian Plant Quizalofop-P-Ethyl Exposure .......... 58

Effects Characterization.......................................................................................................... 62

Terrestrial Vertebrate Toxicology....................................................................................... 62

Effects on Birds............................................................................................................... 62

Effects on Mammals........................................................................................................ 63

Terrestrial Invertebrate Toxicology .................................................................................... 65

Aquatic Vertebrate (Fish) Toxicology ................................................................................ 66

Effects to Freshwater Fish and Aquatic-Phase Amphibians ........................................... 66

Effects to Estuarine-Marine Fish..................................................................................... 67

Aquatic Invertebrate Toxicology ........................................................................................ 68

Effects to Freshwater Invertebrates................................................................................. 68

Effects to Estuarine-Marine Invertebrates....................................................................... 69

Terrestrial Plant Toxicology................................................................................................ 70

Aquatic Plant Toxicology.................................................................................................... 73

Results: Risk Characterization................................................................................................ 75

Risk Estimation ................................................................................................................... 75
xiv

Direct Effects to Non-Target Terrestrial Vertebrates...................................................... 75

Direct Effects to Birds, Reptiles, and (land-phase) Amphibians............................................ 75

Direct Effects to Mammals..................................................................................................... 79

Direct Effects to Non-Target Terrestrial Invertebrates.................................................... 83

Direct Effects to Terrestrial and Wetland/Riparian Plants.............................................. 83

Direct Effects to Freshwater Fish (Amphibians), Invertebrates and Estuarine-Marine 

Fish (Amphibians) and Invertebrates, and Aquatic Plants.............................................. 86

Probit Slope Response Analysis of LOC Values and Acute RQ Values....................... 106

Risk Description................................................................................................................ 107

Direct Effects to Terrestrial Birds, Reptiles, and Amphibians ............................................. 108

Direct Effects to Terrestrial Mammals ................................................................................. 110

Direct Effects to Terrestrial Invertebrates............................................................................. 112

Direct Effects to Terrestrial Plants........................................................................................ 113

Direct Effects to Aquatic Fish, Invertebrates, and Plants..................................................... 117

Listed Species Effects Analysis..................................................................................... 120

Action Area........................................................................................................................... 127

Effects Area Determination .................................................................................................. 127

Uncertainties......................................................................................................................... 131

Effects and Risk Assessment Uncertainties ...................................................................... 131

Ecotoxicity Data Gaps................................................................................................... 131

Application Rates .......................................................................................................... 132

Fate Data Gaps............................................................................................................... 133

Incomplete Life Histories of Listed Species.................................................................. 133

Locations of Listed Species........................................................................................... 133

Other Routes of Exposure.............................................................................................. 133

Foliar Dissipation Half-life............................................................................................ 134

Species Sensitivity......................................................................................................... 134

Endocrine Disruptor Screening Program (EDSP) ......................................................... 134

 Spatial Analyses...................................................................................133

References............................................................................................................................. 136

Appendix B – Aryloxyphenoxypropionate Chemical Family (“FOPs”) .............................. 146

Appendix C – Chemical Structures and Maximum Degradate Formation ........................... 147

Appendix D – ECOTOX Literature Search .......................................................................... 151

Appendix E – SIP and STIR Model Output.......................................................................... 165

Appendix F – Risk Quotient Method and Levels of Concern .............................................. 168

Appendix G – Surface Water Model Results and Sample Input and Outputs...................... 170

Appendix H – TerrPlant Output............................................................................................ 173

Appendix I – T-REX Output................................................................................................. 175
xv

List of Abbreviated Terms and Symbols

@ symbol for “at”

% symbol for “percent”

> symbol for “greater than”

< symbol for “less than”

μg/L symbol for “micrograms per liter”

oC symbol for “degrees Celsius”

ai active ingredient

Acc# accession number

BEAD Biological and Economical Analysis Division

bw body weight

CI confidence interval

CL confidence limit

DP# data package

EC emulsifiable concentrate

EC25 25% effect concentration

EC50 50% (or median) effect concentration

ECOTOX EPA managed database

EEC estimated environmental concentration

EFED Environmental Fate and Effects Division

e.g. Latin exempli gratia (“for example”)

et al. Latin et alii (“and others”)

etc. Latin et cetera (“and the rest” or “and so forth”)

FESTF FIFRA Endangered Species Task Force

FIFRA Federal Insecticide Fungicide and Rodenticide Act

FQPA Food Quality Protection Act

ft feet

g gram

GENEEC Generic Estimated Exposure Concentration model

IC50 50% (or median) inhibition concentration

i.e. Latin for id est (“that is”)

IMS information management system

Kg kilogram(s)

Km kilometer(s)

Koc symbol for the organic carbon partitioning coefficient

LAA likely to adversely affect

Lbs pounds

lb ai/A pound(s) of active ingredient per acre

LC50 50% (or median) lethal concentration

LD50 50% (or median) lethal dose
xvi

LOAEC lowest observable adverse effect concentration

LOAEL lowest observable adverse effect level

LOC level of concern

LOD level of detection

LOEC lowest observable effect concentration

Kow symbol for the octanol water partitioning coefficient

LOQ level of quantitation

LUIS label use information system

m meter(s)

MA may affect

mg milligram(s)

mg/kg milligrams per kilogram (equivalent to ppm, except in the 

case of discussing dose such as mg/kg-bw)

mg/L milligrams per liter (equivalent to ppm)

mi mile(s)

MM may modify primary constituent element

MM/NSF may modify primary constituent element/no shapefile

mmHg millimeter of mercury

MRID master record identification number

MW molecular weight

NASS National Agricultural Statistics Service

NAWQA National Water Quality Assessment

NE no effect

NLAA not likely to adversely affect

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric Administration

NOAEC no observable adverse effect concentration

NOAEL no observable adverse effect level

NOEC no observable effect concentration

OCSPP Office of Chemical Safety and Pollution Prevention

OPP Office of Pesticide Programs

OPPTS Office of Prevention, Pesticides and Toxic Substances

pH symbol for the negative logarithm of the hydrogen ion 

activity in an aqueous solution, dimensionless

pKa symbol for the negative logarithm of the acid dissociation 

constant, dimensionless

ppb parts per billion (equivalent to μg/L or μg/kg)

ppm parts per million (equivalent to mg/L or mg/kg)

SLUA screening level usage analysis

USDA United States Department of Agriculture
xvii

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey

Wt weight
18

Introduction

Purpose of Assessment

The purpose of this assessment is to evaluate the potential risks of quizalofop-p-ethyl’s 

registered uses on federally listed endangered and threatened (“listed”) species and all other 

non-target plant and animal (“non-listed”) species. This risk assessment incorporates the 

available effects data, modeling, and risk methodologies, some of which may not have been 

available at the time when previous quizalofop-p-ethyl registration actions occurred. Risks 

from direct and indirect effects are derived and evaluated in accordance with the risk 

assessment methodology described in the Agency’s Overview Document (USEPA, 2004). 

These risk findings are then used as part of an “effects determination” for listed species. The 

Agency will reach one of the following three conclusions regarding the potential for the 

registered quizalofop-p-ethyl use on food and non-food crops to affect federally listed 

species:

“No effect”; 

“May affect, but not likely to adversely affect”; or

“May affect, and likely to adversely affect”. 

If the results of the risk assessment show no indirect effects and the levels of concern (LOC) 

are not exceeded for direct effects for a given listed species taxonomic grouping (e.g., 

freshwater fish, small herbivorous mammal), a “no effect” (NE) determination is made, 

based on quizalofop-p-ethyl’s use within the action area for “species” with the given 

taxonomic group. If, however, there is a potential for indirect effects and/or exposure 

exceeds the listed species LOC values for direct effects for a given group, the Agency 

concludes a preliminary “may affect” (MA) “species” within the taxonomic group. The 

Agency then considers additional lines of evidence such as the geographical nature of the 

exposure, as well as more in-depth evaluations of the toxicological and ecological 

requirements to determine a rationale for a “not likely to adversely affect” (NLAA) or “likely 

to adversely affect” (LAA) determination.

Similarly the Agency will reach one of the following conclusions regarding the potential for 

quizalofop-p-ethyl uses to result in destruction or adverse modification of critical habitat:

“No effect”; 

“May Modify Primary Constituent Elements”

The Agency uses the risk assessment analysis for direct effects to categories of biological 

resource requirements to draw conclusions about effects to principle constituent elements of 
19

critical habitat. The Agency is limited in a practical sense to those principle constituent 

elements of critical habitat that are of a biological nature. If the results of the risk assessment 

show that no LOC is exceeded for all taxonomic groups a “no effect” (NE) determination for 

habitat modification is made. If a LOC is exceeded for one or more taxonomic groupings the 

Agency then considers additional lines of evidence such as direct effects to the species, the 

type and degree of effect on the taxonomic groupings, expected resultant effects on 

biologically mediated environmental processes (e.g., increased sedimentation from loss of 

vegetation) as compared to baseline environmental conditions, co-occurrence of the action 

area with critical habitat, the type of principle constituent elements associated with critical 

habitat for listed species in a taxonomic grouping to determine a rationale for a “may modify 

primary constituent elements”.

Problem Formulation

The problem formulation for this assessment and effects determination was provided in the 

USEPA Registration Review – EFED Problem Formulation for Quizalofop-p-ethyl 

Registration Review November 7, 2007 document. Data were requested for four studies; 

classifications after EFED evaluation are listed in parentheses:

850.4225 – Seedling emergence tier II (“supplemental” classification)

850.2300 – Vegetative vigor tier II (“supplemental” classification)

850.4100 – Algal toxicity tiers I and II (“acceptable” classification)

Special Study – Aquatic emergent study conducted on rice (“acceptable” 

classification)

All submitted studies for quizalofop-ethyl and quizalofop-p-ethyl are listed in the MRID 

bibliography in Appendix A.

There were two modifications to the risk assessment process originally proposed in the 

problem formulation.

Registrations for rapeseed subgroup 20A, herbicide-tolerant field corn seed 

production, and herbicide-tolerant sorghum were added to the quizalofop-p-ethyl 

label. These were added to the uses assessed in this risk assessment. 

3-OH-quizalofop acid was added as a degradate of concern and therefore, included in 

the total residue EECs. This degradate was only identified in one relatively recently 

submitted fate study (MRID 43235603).

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

distributed or sold in the United States generally must be registered by the United States 
20

Environmental Protection Agency (USEPA). To determine whether a pesticide can be 

registered, the USEPA evaluates its safety to non-target species based on a wide range of 

environmental and health effects studies. In 1996, FIFRA was amended by the Food Quality 

Protection Act (FQPA), and EPA was mandated to implement a new program for the 

periodic review of pesticides, i.e., registration review1. The registration review program is 

intended to ensure that as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no unreasonable 

adverse effects to human health and the environment. Changes in science, public policy, and 

pesticide use practices will occur over time. Through the registration review program, the 

Agency periodically reevaluates pesticides to make sure that as change occurs, products in 

the marketplace can be used safely.

Previous Risk Assessments

The most recent completed screening level risk assessments for use on rapeseed subgroup 

20a, sorghum containing the DuPontTM InzenTM AII Herbicide Tolerance Trait, and corn 

containing DAS-4027809 (USEPA 2011a, DP Barcode D384583/386679) identified direct

risks to mammals and terrestrial plants. In the absence of data, direct risks were assumed for 

aquatic vascular plants and estuarine/marine fish. Indirect risks were assumed for all listed 

taxa because of their potential dependence on monocots for survival.

Stressor Source and Distribution

MECHANISM OF ACTION AND SIDE EFFECTS

Quizalofop-p-ethyl is an organic phenoxy herbicide that belongs to a subclass of phenoxy 

compounds known as aryloxyphenoxys (fops; Appendix B). Herbicides categorized as 

aryloxyphenoxys have several modes of action in terrestrial and aquatic vascular and non 

vascular plants: (1) inhibition of acetyl CoA carboxylase (ACCase), a key enzyme in lipid 

biosynthesis; (2) inhibition of cell mitosis or immediate termination of mitosis once exposure 

has been known to occur; and (3) inhibition of Acetyl-CoA carboxylase and the fatty acid 

synthesis pathway causes an inhibition of thylakoid membrane formation, chloroplast 

formation and multiplication, and finally a halt of cell membrane formation and cell division.

Quizalofop-p-ethyl is absorbed from the leaf surface and moved throughout the plant. It 

accumulates in the active growing regions of stems and roots. Through ingestion, 

quizalofop-p-ethyl can affect the muscle membranes of terrestrial mammals causing 

increased irritability and rigidity followed by paralysis. Also, quizalofop-p-ethyl, like many 

of the other phenoxy herbicides, may induce severe gastrointestinal effects in mammals after 

moderate toxic exposure. Gastrointestinal effects often include: (1) vomiting; 

(2) unquenchable thirst; (3) severe diarrhea (with the appearance of specks of blood); and (4) 

frequent urination (Adams, 1999). Quizalofop-p-ethyl is known to initiate muscular control 

 

1

http://www.epa.gov/oppsrrd1/registration_review/
21

problems in aquatic organisms (fish, invertebrates, and amphibians) once these organisms 

have been exposed to certain dose levels (Adams, 1999).

OVERVIEW OF PESTICIDE USE AND USAGE

Quizalofop-p-ethyl, also known by the trade names Assure II, Matador, Quizalofop, and 

Targa, is an herbicide that is currently registered for application to a number of food and nonfood crops to control monocot weeds, including some varieties of volunteer monocot crops 

(e.g., sorghum, corn). It was recently registered on herbicide-tolerant corn for seed 

production and herbicide-tolerant sorghum. Registered application methods for quizalofopp-ethyl are aerial, ground, low-pressure ground, band, tractor-mounted, and hooded sprayer. 

It is registered for use on a number of food and non-food crops including grains, noncultivated areas, beans, cotton, mint, ornamental trees, soybean, and grasses. Five different 

companies currently have registered products with quizalofop-p-ethyl concentrations ranging 

from 1.4 to 10.3 percent (Tables 1 and 2). 

An average of 53,500 pounds of quizalofop-p-ethyl (averaged from 2003-2010) is applied on 

agricultural crops in the United States each year with the majority being applied to dry 

beans/peas and soybeans (20,000 lb each). Quizalofop-p-ethyl is also used on sunflowers 

(4000 lb), sugar beets (3000 lb), canola/rapeseed (2000 lb), alfalfa and cotton (1000 lb each), 

and barley, green beans, garlic, onions, and green peas (<500 lb each) (USEPA 2011b)

2

. 

 

2 Based on USDA-NASS (United States Department of Agriculture’s National Agricultural Statistics Service) 

and Private Pesticide Market Research
22

Table 1. Current registrations for quizalofop-p-ethyl

Product Name Registrant

EPA 

Registration #

(latest label 

date)

Active 

Ingredient

(% w/w)

Form Use(s)

Targa Herbicide Nissan Chemical 

Industries, Ltd.

33906-9

4/6/10 10.3 Emulsifiable concentrate

Alfalfa (non-food/non-feed for seed production), barley, 

canola/rape, carrot (non-food/non-feed for seed 

production), Chinese cabbage (non-food/non-feed for 

seed production), cotton, crambe, dry beans, dry and 

succulent peas, fallow, flax, garlic (non-food/non-feed 

for seed production), lentils, mint (spearmint and 

peppermint), non-crop areas (uncultivated areas, fence 

rows, roadsides, equipment storage areas, and other 

similar areas), onion (non-food/non-feed for seed 

production), ornamental and/or shade trees, paved areas 

(private roads/sidewalks), perennial ryegrass grown for 

seed, pineapple, radish (non-food/non-feed for seed 

production), red beets (non-food/non-feed for seed 

production), snap beans, soybeans, spinach (nonfood/non-feed for seed production), sugar beets, 

sunflowers, Swiss chard (non-food/non-feed for seed 

production), wheat
23

Product Name Registrant

EPA 

Registration #

(latest label 

date)

Active 

Ingredient

(% w/w)

Form Use(s)

DuPont Assure II 

Herbicide

E. I. Du Pont de 

Nemours and 

Company

352-541

4/12/12 10.3 Emulsifiable concentrate

Alfalfa (non-food/non-feed for seed production), 

canola/rape, carrot (non-food/non-feed for seed 

production), Chinese cabbage (non-food/non-feed for 

seed production), cotton, crambe, dry beans, dry and 

succulent peas, flax, garbanzos (including chick peas), 

garlic (non-food/non-feed for seed production), Hybrid 

cottonwood/poplar plantations, lentils, mint (spearmint 

and peppermint), non-crop areas (uncultivated areas, 

fence rows, roadsides, equipment storage areas, and 

other similar areas), onion (non-food/non-feed for seed 

production), ornamental and/or shade trees, Perennial 

ryegrass grown for seed, pineapple, radish (nonfood/non-feed for seed production), red beets (nonfood/non-feed for seed production), snap beans, 

sorghum (herbicide tolerant), soybeans, spinach (nonfood/non-feed for seed production), sugar beets, 

sunflowers, Swiss chard (non-food/non-feed for seed 

production)
24

Product Name Registrant

EPA 

Registration #

(latest label 

date)

Active 

Ingredient

(% w/w)

Form Use(s)

Quizalofop EC Sharda USA, LLC 83529-15

3/11/09 10.3 Emulsifiable concentrate

Alfalfa (non-food/non-feed for seed production), 

canola/rape, carrot (non-food/non-feed for seed 

production), Chinese cabbage (non-food/non-feed for 

seed production), cotton, crambe, dry beans, dry and 

succulent peas, flax, garbanzos (including chick peas), 

garlic (non-food/non-feed for seed production), hybrid 

cottonwood/poplar plantations, lentils, mint (spearmint 

and peppermint), non-crop areas (uncultivated areas, 

fence rows, roadsides, equipment storage areas, and 

other similar areas), onion (non-food/non-feed for seed 

production), ornamental and/or shade trees, paved areas 

(private roads/sidewalks), perennial ryegrass grown for 

seed, pineapple, radish (non-food/non-feed for seed 

production), red beets (non-food/non-feed for seed 

production), snap beans, soybeans, spinach (nonfood/non-feed for seed production), sugar beets, 

sunflowers, Swiss chard (non-food/non-feed for seed 

production)

Mon 78746 Herbicide Monsanto 

Company

524-523

8/28/00 1.4 Ready-to-use Cotton, soybeans

Matador Herbicide

FMC Corp. 

Agricultural 

Products Group

279-3183

2/13/97 10.3 Emulsifiable concentrate

Cotton, soybeans

DuPont Assure II 

Herbicide

E. I. Du Pont de 

Nemours and 

Company

HI110001

11/16/11

IL110001

6/9/11

IN110003

5/3/11

Section 24c

10.3 Emulsifiable 

concentrate

Field corn seed production (herbicide-tolerant)

DuPont Assure II 

Herbicide

Agro Servicios, 

Inc.

PR110002

11/3/11 10.3 Emulsifiable concentrate

Field corn seed production (herbicide-tolerant)
25

Product Name Registrant

EPA 

Registration #

(latest label 

date)

Active 

Ingredient

(% w/w)

Form Use(s)

DuPont Assure II 

Herbicide

E. I. Du Pont de 

Nemours and 

Company

ME050002

8/19/05

MN000006

11/29/00

10.3 Emulsifiable 

concentrate

Hybrid cottonwood/poplar plantations
26

Table 2. Use and application rate information for quizalofop-p-ethyl

Crop

Maximum 

Application 

Rate

Application 

Method

Shortest 

Application 

Interval

(days)

Reg. #1

Idaho, Montana, Washington, 

Oregon, and Wyoming only

Non-food/non-feed for seed 

production: 

Alfalfa, carrot, Chinese cabbage, 

garlic, onion, radish, red beets, 

spinach, Swiss chard 

All states, food item:

Sugar beets

Single max = 

0.0834 lb ai/A

Seasonal max = 

0.174 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

Except New York

Barley, wheat

Single max = 

0.0695 lb ai/A 

Seasonal max = 

0.0695 lb ai/A

Spray (aerial 

and ground)

N/A 33906-9

Canola/rape, crambe, soybeans, 

sunflowers

Single max = 

0.0834 lb ai/A

Seasonal max = 

0.125 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

524-523 (soybean)

279-3183 (soybean)

Field corn seed production 

(herbicide-tolerant)

Single max = 

0.0834 lb ai/A

Seasonal max = 

0.0834 lb ai/A 

(corn)

Spray (aerial 

and ground)

N/A HI110001

IL110001

IN110003

PR110002

352-541

Cotton Single max = 

0.034 lb ai/A

Seasonal max = 

0.125 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

524-523

279-3183

Dry beans Single max = 

0.0834 lb ai/A

Seasonal max = 

0.195 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

Dry and succulent peas, lentils, snap 

beans

Single max = 

0.0834 lb ai/A

Seasonal max = 

0.0973 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15
27

Crop

Maximum 

Application 

Rate

Application 

Method

Shortest 

Application 

Interval

(days)

Reg. #1

Texas, Oklahoma, Kansas, and 

Colorado only

Fallow

Single max = 

0.0834 lb ai/A

Seasonal max = 

0.21 lb ai/A

Spray (aerial 

and ground)

7 33906-9

Flax, garbanzos (including chick 

peas)

Single max = 

0.0834 lb ai/A 

Seasonal max =

0.167 lb ai/A

Spray (aerial 

and ground)

7 33906-9 (garbanzos 

excluded)

352-541

83529-15

Maine and Minnesota only

Hybrid cottonwood/poplar 

plantations

Single max = 

0.0695 lb ai/A

Seasonal max = 

NS3

Spray (aerial 

and ground)

7 352-541

83529-15

ME050002

MN000006

Mint (spearmint and peppermint) Single max = 

0.0834 lb ai/A

Seasonal max = 

0.209 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

Non-crop areas (uncultivated areas, 

fence rows, roadsides, equipment 

storage areas, and other similar 

areas)

Single max = 

0.111 lb ai/A

Seasonal max = 

0.222 lb ai/A3

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

Puerto Rico (pineapple only) and 

Hawaii only

Ornamental and/or shade trees, 

pineapple

Single max = 

0.208 lb ai/A

Seasonal max = 

0.417 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15

Paved areas (private roads/sidewalks) Single max = 

0.108 lb ai/A 

Seasonal max = 

NS2

Spray (aerial 

and ground)

N/A 33906-9

352-541

83529-15

Minnesota only

Perennial ryegrass grown for seed

Single max = 

0.0695 lb ai/A

Seasonal max = 

0.139 lb ai/A

Spray (aerial 

and ground)

7 33906-9

352-541

83529-15
28

Crop

Maximum 

Application 

Rate

Application 

Method

Shortest 

Application 

Interval

(days)

Reg. #1

Sorghum (herbicide-tolerant) Single max = 

0.0834 lb ai/A

Seasonal max = 

0.14 lb ai/A

Spray (aerial) 

and ground

7 352-541

N/A- not applicable

NS - not specified on label

1Application rates represent maximum application rate for a least one of the EPA Reg. # listed. Other labels 

may have slightly different application rates.

2Assuming the seasonal maximum is equivalent to the single application rate

3Assuming two applications at the highest rate for the seasonal maximum
29

Environmental Fate and Transport

SUMMARY OF ENVIRONMENTAL FATE

Quizalofop-p-ethyl is relatively stable to hydrolysis at pHs of 5 and 7, but degrades much 

faster at pH 9 with a half life of 2 days. At pHs 5, 7, and 9, the only degradate formed was 

quizalofop acid (the active ingredient). Therefore, quizalofop acid is stable to abiotic 

hydrolysis. 

Quizalofop-p-ethyl is relatively stable to photolysis in water and soil (t1/2 > 40 days). 

Laboratory aerobic soil metabolism studies show that quizalofop-p-ethyl degrades with a 

half-life of ~30 days to quizalofop acid, 3-OH-quizalofop acid, and phenolic compounds. 

This compares with the terrestrial field dissipation (TFD) study that produced quizalofop-pethyl half-lives of 1 to 12 days with degradates of quizalofop acid and 3-OH-quizalofop acid. 

Based on available fate studies, quizalofop acid appears to be less persistent than both the 

parent and 3-OH-quizalofop acid under aerobic conditions, but similar in mobility to the 

parent compound. As for mobility, the mean adsorption Koc of quizalofop acid is 256 ml/g, 

whereas the mean adsorption Koc value of quizalofop-p-ethyl is 298 (both classified as 

moderately mobile). 

The submitted fish bioaccumulation study was conducted under static conditions (not flowthrough). Given that quizalofop-p-ethyl degraded to quizalofop acid during the study (99% 

quizalofop acid in water at 28 days) and the highest accumulation of radioactive residues 

occurred in the first few days of the 28-day exposure period, it is EFED’s interpretation that 

the initial peak exposures (3900x and 4600x for the 0.004 and 0.04 mg ai/L exposures, 

respectively) are likely more reflective of quizalofop-p-ethyl’s ability to bioaccumulate, the 

28-day values (1X and 4X for exposure concentrations of 0.004 and 0.04 mg ai/L exposures, 

respectively) are more reflective of quizalofop acid’s ability to bioaccumulate (Table 3). 

Quizalofop acid and 3-OH-quizalofop acid are degradates of concern for aquatic exposures. 

Quizalofop acid is the active ingredient. For chemicals in the Aryloxyphenoxypropionate 

Chemical Family (“FOPs”), the relatively non-polar parent molecule undergoes hydrolysis to 

form a more polar (“semi-polar”) acid. Having a non-polar parent molecule (quizalofop-pethyl) aids in penetrating the waxy cuticle of a plant leaf, while the semi-polar quizalofop 

acid is better able to cross the cell wall and cell membrane. Quizalofop acid has also been 

detected in livestock tissues and is included in the tolerance expression and the HED risk 

assessment. The mammalian toxicity level was determined by HED to be equivalent to or 

less than that of the parent. 

Appendix B compares the structures of the parent and acid degradates for all of the FOPs. 

The right half of the acid degradates is the structurally similar, which helps explain the 

similar mode of action across the FOP family. The oxygen of the rightmost hydroxy group 

of the degradates is attached to various non-polar substituent groups in the parent molecules.
30

3-OH-quizalofop acid is included as a residue of concern because of its similar structure to 

quizalofop acid. The only registrant-submitted laboratory study that identified this degradate 

(maximum of 21% of applied radioactivity at 60 days) was an aerobic soil metabolism study 

(MRID 43235603). The only registrant-submitted field study that identified this degradate 

(maximum of 5.4 ng/g at 58 days) was a terrestrial field dissipation study (MRID 47408416). 

Chemical structures and information on the maximum amount of degradate formation in each 

of the environmental fate studies can be found in Appendix C.

For ecological risk assessment purposes, the toxicity of quizalofop-p-ethyl, quizalofop acid,

and 3-OH-quizalofop acid will be considered to be roughly equivalent. This assumption is 

conservative; a review of the European Footprint Database 

(http://sitem.herts.ac.uk/aeru/footprint/en/index.htm) indicates that major degradates are of 

similar toxicity, or in many cases, less toxic than the parent. Given that the Agency has not 

reviewed the studies from which these database entries were made, a total toxic residues 

(TTR) approach will be used in this risk assessment. The TTR approach models the three 

chemicals (parent and two degradates) and un-extracted residues as one chemical by

adjusting the parent exposure half-lives to account for the duration of exposure to all three 

chemicals of concern (and their un-extracted residues). 
31

Table 3. Physical, chemical, and environmental fate properties of quizalofop-p-ethyl, quizalofop acid and 3-OH-quizalofop 

acid

Quizalofop-P-Ethyl Quizalofop Acid 3-OH-quizalofop Acid

Parameter Value Source/MRID # Value Source/MRID # Value Source/MRID #

Chemical name

Ethyl (R)-2-[4-(6-

chloroquinoxalin-2-yl 

oxy)-phenoxy]propionate

Assure II Label

2-[4-[(6-chloro-2-

quinoxalinyl)oxy]phenoxy

]propanoic acid

PPDB (CAS

name)

(R)-2-[4-(6-chloro-3-

hydroxyquinoxalin-2-

yloxy)phenoxy]pro-pionic 

acid

PPDB (CAS name)

Chemical family Aryloxyphenoxys PPDB

Aryloxyphenoxypropionic 

acid PPDB

Aryloxyphenoxypropionic 

acid PPDB

Empirical formula C19H17ClN2O4 PPDB C17H13ClN2O4 PPDB C17H13ClN2O5 EPI Suite 4.1

Structure

Molecular mass 372.8 g/mol PPDB 344.76 g/mol EPI Suite 4.1 360.76 g/mol EPI Suite 4.1

Water solubility (20 C) 0.4 mg/L Product Chemistry 0.3 mg/L Tomlin, C. 1994 115.7 mg/L EPI Suite 4.1 

(WSKOW v1.41)

Vapor pressure 3 × 10-7 mm Hg @ 20 C Product Chemistry

5.72 × 10-8 mm Hg @ 

25 C

EPI Suite 4.1 

(Modified Grain 

Method)

4.03 × 10-12 mm Hg @ 

25 C

EPI Suite 4.1 

(Modified Grain

Method)

Octanol/water partition 

coefficient (Log Kow)

4.61 PPDB 3.57 EPI Suite 4.1 

(KowWIN v1.67) 3.09 EPI Suite 4.1 (KowWIN v1.67)

Hydrolysis (t1/2)

>600 days @ pH5

30 days @ pH7

2 days @ pH9

MRID 00131583 Stable1 MRID 00131583 Unknown

Direct Aqueous

Photolysis (t1/2)

69 days MRID 00146693 Unknown Unknown

Soil Photolysis 41 days MRID 40336002 Unknown Unknown

Aerobic Soil 

Metabolism (t1/2)

30 days

37 days

MRID 00146695

MRID 43235603 Unknown2 Unknown

N

N

Cl

O

O C

H

CH3

C

O

O C

H2

CH3 N

N

Cl

O

O C

H

CH3

C

O

OH N

N

Cl

O

O C

H

CH3

C

O

OH

HO
32

Quizalofop-P-Ethyl Quizalofop Acid 3-OH-quizalofop Acid

Parameter Value Source/MRID # Value Source/MRID # Value Source/MRID #

Anaerobic Soil 

Metabolism (t1/2)

Unknown MRID 00146696 is 

unacceptable. Unknown Unknown

Aerobic Aquatic 

Metabolism (t1/2)

Unknown No study 

submitted Unknown Unknown

Anaerobic Aquatic 

Metabolism (t1/2)

107 and 95 days MRID 00146697 Unknown Unknown

Soil Partition 

Coefficient (Koc)

298 ml/g

Mean quizalofopacid Koc (436, 267, 

302, and 187) 

(MRID 00146698)

256 ml/g

Mean quizalofopacid Koc (136, 90, 

372, 425) (MRID 

00146947)

Unknown

Terrestrial Field 

Dissipation (t1/2)

United Kingdom – 2.2 

days

Germany – 1.6 days

Southern France – 1 day

Spain – 12 days

MRID 474084146 Unknown2 Unknown

Fish Bioconcentration 

Factor

(Static exposure 

conditions – 99% of 

applied quizalofopethyl had converted to 

quizalofop acid by day 

28 in the water.) 

0.004 μg/L Exposure

Muscle BCF = 16

Viscera BCF =3900

Carcass BCF =31

Whole Fish BCF = 290

0.04 μg/L Exposure

Muscle BCF = 10

Viscera BCF = 4600

Carcass BCF = 37

Whole Fish BCF = 380

MRID 00131583

(Peak BCF 

occurred in the 

first few days of 

the experiment and 

decreased 

presumably as 

quizalofop acid 

formed.)

Unknown, but presumably 

much lower than 

quizalofop-ethyl

MRID 00131583 Unknown

PPDB = Pesticide Properties Database (http://sitem.herts.ac.uk/aeru/projects/ppdb/index.htm)

1 No degradates formed in the quizalofop-p-ethyl hydrolysis study (MRID 00131583) other than quizalofop acid, which indicates the quizalofop acid formed did 

not degrade.

2 Data appears in the footprint database (a pesticide data base used by the European Union - http://sitem.herts.ac.uk/aeru/footprint/en/index.htm) that may or may 

not be suitable for risk assessment that has not been submitted to the Agency for review. 
33

Receptors

EFFECTS TO ORGANISMS

Studies are available for both quizalofop-p-ethyl (the concentrated active isomer) and 

quizalofop-ethyl (50/50 racemic mixture of active and inactive isomers). The most sensitive 

toxicity value was selected for the risk analysis, regardless of the chemical form.

Registrant Submitted Studies for Quizalofop-P-Ethyl

The registrant(s) have submitted a number of studies in support of quizalofop-p-ethyl new 

use registrations and registration review that are considered scientifically sound for use in 

risk assessments. Seven acute freshwater fish studies indicate quizalofop-p-ethyl (3 studies) 

and quizalofop-ethyl (4 studies) is slightly to highly toxic. Chronic freshwater and 

estuarine/marine fish studies also are available. Four acute freshwater invertebrate studies (2 

each for quizalofop-p-ethyl and quizalofop-ethyl) show the chemical to be slightly toxic to 

highly toxic to the waterflea. Acute estuarine/marine invertebrate toxicity testing indicates

quizalofop-p-ethyl (1 study) and quizalofop-ethyl (2 studies) to be highly toxic. Five nonvascular plant studies and two vascular aquatic plant studies are available for quizalofop-pethyl.

For terrestrial organisms, acute toxicity studies are available for birds, with quizalofop-ethyl 

(5 studies), that indicate it is practically non-toxic to birds. Two chronic studies with 

quizalofop-p-ethyl are also available. Rat studies with quizalofop-ethyl indicate it is slightly 

toxic on an acute oral basis; a two generation rat study is also available. Quizalofop-p-ethyl 

is classified as practically non-toxic to honeybees. A number of studies were performed on 

terrestrial plants with both quizalofop-p-ethyl (3 studies) and quizalofop-ethyl (2 studies) 

typical end-use products that documented the toxicity to dicots and monocots.

Open Literature Studies

Open literature studies from the ECOTOX database were reviewed for inclusion in the risk 

assessment. Studies were screened to determine if they provided information about species 

for which EFED does not usually receive information, or lower toxicity endpoints than 

registrant-submitted studies. No additional studies from ECOTOX were identified. All 

ECOTOX papers and rationales of why they were not included in the risk assessment are 

listed in Appendix D.

INCIDENT DATABASE REVIEW

A review of the Ecological Incident Information System on September 26, 2012 (EIIS, 

version 2.1.1), which is maintained by the Agency’s Office of Pesticide Programs, the 

Aggregate Summary Module of OPP’s Incident Database, and the Avian Monitoring 

Information System (AIMS), which is maintained by the American Bird Conservancy, was 

conducted for both quizalofop-p-ethyl and quizalofop-ethyl.
34

According to Office of Pesticides Program Ecological Incident Information System (EIIS), 

one incident for quizalofop-p-ethyl has been reported. The incident (I016677-001) occurred 

when spray drift from an application of Assure II (quizalofop-p-ethyl) and Flexstar (sodium 

fomesafen) to soybeans came into contact with a garden in the vicinity of the soybean field. 

Hundreds of herbaceous plants in a home herb garden (20 ft away) and various vegetables in 

another garden (150 ft away) were reported to have been damaged (leaf burn and spotting). 

The incident occurred on 8/2/05 in Missouri and is classified as “possible” to have been 

caused by quizalofop-p-ethyl; however there is some uncertainty given that sodium 

fomesafen was also applied. 

There was one minor incident listed in the Aggregate Summary Module of OPP’s Incident 

Database for quizalofop-p-ethyl. The formulation, Assure II, was associated with minor 

plant damage between 7/1/01 and 9/30/01. No further information was available. There 

were no quizalofop incidents reported in the AIMS database and EFED is unaware of other 

incidents outside of these three databases.

DATA GAPS IDENTIFIED

The following toxicity data gaps have been identified:

OPPTS 850.1075- Acute Estuarine/Marine Fish Toxicity Test

OPPTS 850.1350- Chronic Estuarine/Marine Invertebrate Toxicity Test

OPPTS 850.2100- Acute Oral Toxicity Test with a Passerine Species

These data were not identified as gaps in the quizalofop-p-ethyl problem formulation. At the 

time, an acute estuarine/marine fish study had been submitted by the registrant. The study 

was assumed to be acceptable, but was found to be invalid when it was formally reviewed 

several years later. Data were not requested for chronic effects to estuarine/marine 

invertebrates because it was possible to calculate an acute-to-chronic ratio to estimate that 

toxicity value. Finally, the acute oral toxicity test with a passerine species did not become a 

data requirement until after the data call-in was issued.

ECOSYSTEMS POTENTIALLY AT RISK

The ecosystems at risk are often extensive in scope, and as a result it may not be possible to 

be specific at the screening level. Quizalofop-p-ethyl is registered on a variety of food (e.g., 

grains, beans, mint, pineapple) and non-food (cotton, non-agricultural areas, ornamentals, 

seed production) uses. In general terms, terrestrial ecosystems potentially at risk could 

include the areas next to treated fields, plantations, roadsides, fencerows, equipment storage 

areas, and paved areas. These areas could include cultivated fields, fencerows and 

hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats and other 

uncultivated areas. 
35

Aquatic ecosystems potentially at risk include water bodies adjacent to or downstream from 

the treated area and might include impounded bodies such as ponds, lakes and reservoirs, or 

flowing waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also 

includes marine ecosystems and estuaries. 

All of the uses apply quizalofop-p-ethyl as a foliar spray (ground or aerial) to vegetation. 

Given the diversity of uses (corn to pineapple), it is expected that quizalofop-p-ethyl 

applications could occur in most areas of the United States. 

Conceptual Model

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

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

the environment from a source to an ecological receptor. For an ecological exposure 

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 (Figures 1 and 2) depicts the potential pathways for ecological risk 

associated with quizalofop-p-ethyl (including its degradates) use. The conceptual model 

provides an overview of the expected exposure routes for organisms within the quizalofop-pethyl action area. For terrestrial organisms, the major route of exposure considered is the 

dietary route; consumption of food items such as plant leaves or insects that have quizalofopp-ethyl residues as a result of spraying and drift. Exposure through inhalation is unlikely 

given quizalofop-p-ethyl’s low vapor pressure and the results of EFED’s Screening Tool for 

Inhalation Risk (STIR v. 1.0). EFED’s Screening Imbibition Program (SIP v. 1.0) indicated 

that drinking water exposure alone was not a potential concern for birds or mammals (acute 

and chronic exposures) (Appendix E). 

For aquatic animal species, the major routes of exposure are considered to be via the 

respiratory surface (gills) or the integument.

Direct contact and/or root uptake is the major route of exposure for terrestrial and wetland 

(riparian) plants, while aquatic plants may be exposed via direct uptake and adsorption. 

Estimated exposure concentrations for all organisms are obtained through the use of several 

Agency exposure models.
36

** Route of exposure includes only ingestion of fish and aquatic invertebrates

Stressor

Source

Receptors

Attribute

Change

Quizalofop-P-Ethyl ( and Degradates) Applications for All Registered Uses

Spray drift

Aquatic animals

Invertebrates 

Vertebrates

**Piscivorous mammals 

and birds

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae and 

vascular plants

Reduction in prey

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to 

habitat

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Atmospheric 

transport

Wet/dry deposition

Soil Leaching to

Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves Riparian plants

terrestrial 

exposure 

pathways see 

Figure 2

Figure 1. Conceptual model for the aquatic effects of quizalofop-p-ethyl applications. 

Dotted lines indicate the pathway is not expected to be significant. 

Stressor

Source

Attribute

Change

Quizalofop-P-Ethyl (and Degradates) Applications for All Registered Uses

Direct

application

Spray drift

Terrestrial 

vertebrates

Terrestrial 

Inverts

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

to habitat

Terrestrial plants

grasses/forbs, fruit, seeds 

(trees, shrubs)

Runoff

Terrestrial 

vertebrates 

Exposure Media 

& Receptors Soil

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport

Root uptake/contact

Wet/dry deposition

Ingestion

Leaching to

Groundwater

Irrigation 

water

Figure 2. Conceptual model for the terrestrial effects of quizalofop-p-ethyl applications.
37

Risk Hypothesis

For quizalofop-p-ethyl and its degradates, the following ecological risk hypotheses are being 

tested in this baseline risk assessment: 

Terrestrial Environment

Exposure to quizalofop-p-ethyl and degradate residues on insects, seeds, foliage, and 

other plant parts from direct deposition or spray drift from the labeled use of the 

pesticide has the potential to cause reduced survival, growth and reproduction to 

terrestrial vertebrates (birds, mammals, reptiles, terrestrial-phase amphibians) and 

terrestrial invertebrates.

Exposure to quizalofop-p-ethyl and degradate residues on foliage, roots, or other 

plant parts from spray drift alone or from runoff from labeled use of the pesticide has 

the potential to result in reduced survival and biomass to upland plants and 

riparian/wetland plants in areas adjacent to a treated area. 

Aquatic Environment

Exposure to quizalofop-p-ethyl and degradate residues in water from spray drift or 

runoff from the labeled uses of the herbicide has the potential to cause reduced 

survival, growth and reproduction to aquatic invertebrates, fish, and plants (vascular 

and non-vascular) in surface waters adjacent to a treated area.

Analysis Plan

In registration review, pesticide ecological risk assessments will follow the Agency’s 

Guidelines for Ecological Risk Assessment and will be in compliance with the paper entitled 

“Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, 

U.S. Environmental Protection Agency” (US EPA, 2004).

The focus of an ecological risk assessment is on both the toxic effects of a pesticide to nontarget organisms and the potential routes of the pesticide’s exposure to non-target organisms. 

In addition to addressing a pesticide’s toxic effects and potential routes of exposure, an 

ecological risk assessment addresses the uncertainties associated with a pesticide’s risk to 

non-target organisms.

MEASURES TO EVALUATE THE RISK HYPOTHESIS AND CONCEPTUAL MODEL

Measures of exposure are based on aquatic and terrestrial models that predict estimated 

environmental concentrations (EECs) of quizalofop-p-ethyl using maximum labeled

application rates and methods of application. The model used to predict aquatic EECs is the 

PRZM [Pesticide Root Zone Model (PRZM v3.12.2)] and EXAMS [EXposure Analysis 
38

Modeling System (v2.98.4.6)] models. The model used to predict terrestrial EECs on food 

items is T-REX [Terrestrial Residue Exposure Model version 1.5 (Mar. 22, 2012)]. The 

model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant [Version 

1.2.2 (10/29/09)].

MEASURES OF EFFECT

Data identified in the Effects Characterization Section are used as measures of effect for 

direct and indirect effects to non-target organisms. Data were obtained from registrant 

submitted studies or from open literature studies identified by ECOTOX. The 

ECOTOXicology database (ECOTOX) was searched to provide more ecological effects data 

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

data for aquatic life, terrestrial plants, and wildlife. ECOTOX was created and is maintained 

by the USEPA, Office of Research and Development, and the National Health and 

Environmental Effects Research Laboratory's Mid-Continent Ecology Division.

The acute measures of effect used for animals in this screening level assessment are the LD50, 

LC50 and EC50. LD stands for “Lethal Dose”, and LD50 is the amount of a material, given all 

at once, that is estimated to cause the death of 50% of the test organisms. LC stands for 

“Lethal Concentration” and LC50 is the concentration of a chemical that is estimated to kill 

50% of the test organisms. EC stands for “Effective Concentration” and the EC50 is the 

concentration of a chemical that is estimated to produce a specific effect in 50% of the test 

organisms. Endpoints for chronic measures of exposure for listed and non-listed animals are 

the NOAEL/NOAEC and NOEC. NOAEL stands for “No Observed-Adverse-Effect-Level” 

and refers to the highest tested dose of a substance that has been reported to have no harmful 

(adverse) effects on test organisms. The NOAEC (i.e., “No-Observed-Adverse-EffectConcentration”) is the highest test concentration at which none of the observed effects were 

statistically different from the control. The NOEC is the No-Observed-EffectsConcentration. For non-listed plants, only acute exposures are assessed (i.e., EC25 for 

terrestrial plants and EC50 for aquatic plants). 

INTEGRATION OF EXPOSURE AND EFFECTS

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

determine the potential ecological risk from agricultural and non-agricultural uses of 

quizalofop-p-ethyl, and the likelihood of direct and indirect effects to non-target organisms in 

aquatic and terrestrial habitats. The exposure and toxicity effects data are integrated to 

evaluate the risks of adverse ecological effects on non-target species. For the assessment of 

quizalofop-p-ethyl risks, the risk quotient (RQ) method is used to compare exposure and 

measured toxicity values. EECs are divided by acute and chronic toxicity values. The 

resulting RQs are then compared to the Agency’s levels of concern (LOCs) (US EPA, 2004). 
39

There is no established acute listed or non-listed LOC for terrestrial invertebrates. The LOCs 

currently in use for birds, mammals and aquatic species are based on 1975 regulations for the 

enforcement of FIFRA (40 CFR Part 154: 49005; 49007; 49016). Refer to Appendix F for 

addition information on the LOCs.

ANALYSIS OF CO-OCCURANCE OF FEDERALLY LISTED SPECIES WITH QUIZALOFOP-PETHYL

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

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

from registered uses of quizalofop-p-ethyl. This assessment will be conducted in accordance 

with the Overview Document (US EPA, 2004), provisions of the ESA, and the Services’ 

Endangered Species Consultation Handbook (U.S. FWS/NMFS, 1998).

In the case of a nation-wide risk assessment conducted under Registration Review, the action 

area will encompass the entire U.S. and its territories. The purpose of defining the action 

area as the entire U.S. and its territories is to ensure that the initial area of consideration 

encompasses all areas where the pesticide may be used now and in the future, including the 

potential for off-site transport via spray drift and downstream dilution. Additionally, the 

concept of a nationwide action area takes into account the potential for direct and indirect 

effects and any potential modification to critical habitat based on ecological effect measures 

associated with reduction in survival, growth, and reproduction, as well as the full suite of 

sub-lethal effects available in the effects literature. 

It is important to note that the nation-wide action area does not imply that direct and/or 

indirect effects and critical habitat modification are expected to or are likely to occur over the 

full extent of the action area, but rather to identify all listed species and critical habitat that 

may potentially be affected by the action. The Agency will use more rigorous analysis 

including consideration of available land cover data, toxicity data, and exposure information 

to determine areas where individual listed species and designated critical habitat may be 

affected or modified via endpoints associated with reduced survival, growth, or reproduction. 

The Information Management System (IMS), a work product of the industry-based FIFRA 

Endangered Species Task Force (FESTF) will be used to evaluate the co-occurrence of listed 

species and critical habitat within the quizalofop-p-ethyl action area. FESTF was formed to 

fulfill data requirements relative to species/pesticide use proximity. 
40

Exposure Assessment

Aquatic Exposure Assessment

Monitoring Data

Quizalofop-p-ethyl, quizalofop acid, and 3-OH-quizalofop acid do not appear to be included 

in the list of the analytes monitored in the U.S. surface and groundwater under the USGS’s 

National Water Quality Assessment (NAWQA) program. There were no available 

monitoring data at the time of this assessment (October 2012).

Aquatic Exposure Modeling

Tier II screening-level surface water exposures for aquatic risk assessment were conducted 

for all registered uses. Modeled application rates represent the maximum use pattern of the 

proposed label for all uses. The aquatic exposure estimates presented in this assessment were 

based on the use of models because no surface or groundwater monitoring data are available 

for quizalofop-p-ethyl within the continental U.S. Two major environmental degradates, 

quizalofop acid and 3-OH-quizalofop acid, were identified in the environmental fate and 

terrestrial field dissipation studies. There are no Agency-reviewed toxicity data related to 

aquatic species for these major degradates that can be used to exclude any of the degradates 

listed above (Europe’s Footprint database3does have data that support the premise that the 

degradates may be less toxic than the parent, but EPA does not have access to these studies 

for evaluation). Therefore, a total residue (parent plus degradates of concern) approach is 

used and expected to provide protective exposure estimation for aquatic organisms exposed 

to the major degradates of quizalofop-p-ethyl. Essentially, this method simply extends the 

duration of the predicted EECs to account for the time it would take for both the parent and 

degradates of concern to dissipate in the environment. It assumes that the degradates have 

equivalent fate and ecotoxicity properties as the parent – a conservative assumption (Table 

4).

TIER II PRZM/EXAMS Model

The Tier II model Pesticide Root Zone Model (PRZM v3.12.2) linked with EXposure 

Analysis Modeling System (EXAMS v2.98.4.6) via the model shell PRZM/EXAMS (PE 

v5.0, Nov. 15, 2006) was used to estimate baseline-level exposures for representative crop 

scenarios. The PRZM model simulates pesticide movement and transformation on and across 

the agricultural field resulting from crop applications. The EXAMS model simulates 

pesticide loading via runoff, erosion, and spray drift assuming a “standard” 1-ha pond, 2-m 

 

3

http://sitem.herts.ac.uk/aeru/footprint/en/index.htm
41

deep (20,000 m3) with no outlet that borders a 10-ha treated field. Simulations are run for 

multiple (usually 30) years, and the Agency estimates peak and running mean values that are 

expected once every ten years based on the daily values generated during the simulation. 

The coupled PE models and users manuals are available from the U.S. Environmental 

Protection Agency Water Models Web-page (U.S. EPA, 2011).

Exposure estimates generated using this “standard” pond are intended to represent a wide 

variety of vulnerable water bodies that occur in the upper reaches of watersheds including 

prairie pot holes, playa lakes, wetlands, vernal pools, man-made and natural ponds, and 

intermittent and first-order streams. As a group, there are factors that make these water 

bodies more or less vulnerable than the standard surrogate pond. Static water bodies that 

have larger ratios of pesticide-treated drainage area to water body volume would be expected 

to have higher peak EECs than the standard pond. These water bodies will be either smaller 

in size or have large drainage areas. Smaller water bodies have limited storage capacity and 

thus may overflow and carry pesticide in the discharge, whereas the standard pond has no 

discharge. As watershed size increases, it becomes increasingly unlikely that the entire 

watershed is planted with a non-major single crop that is all treated simultaneously with the 

pesticide. Headwater streams can also have peak concentrations higher than the standard 

pond, but they likely persist for only short periods of time and are then carried and dissipated 

downstream. 

Table 4. PRZM-EXAMS input parameter values for quizalofop-p-ethyl

Input Parameter Value Comment Source

Single Application Rate (kg 

ai/ha)

See Table 2

Applications per Year

Application Interval (days)

CAM Input 2 Foliar Labels

1

IPSCND Input 1 Default

Input parameter 

guidance 

(USEPA, 2009)

Spray Drift Fraction 1% - ground; 5% - 

aerial Default

Application Efficiency 99% - ground; 95% - 

aerial Default

Molecular Mass (g/mol) 344.8 Quizalofop acid EPI Suite 4.1

Vapor Pressure at 25°C 

(torr)

3 × 10-7Parent quizalofop-pethyl

Product Chemistry

Solubility in Water at 25oC 

(mg/L)

0.4 Parent quizalofop-pethyl

Product Chemistry

Organic Carbon Partition 256 Mean quizalofop-acid MRID 
42

Input Parameter Value Comment Source

Coefficient (KOC) (L/kgOC) Koc (136, 90, 372, 

425)

00146947

Aerobic Soil Metabolism 

Half-life (days)

407 Combined parent, 

quizalofop-acid, 3-

OH-quizalofop acid, 

and bound residues2

MRID 

00146697 

MRID 

43235603

Aerobic Aquatic 

Metabolism Half-life (days)

814 days 2 × aerobic soil

metabolism t1⁄2

Input parameter 

guidance 

(USEPA, 2009)

Anaerobic Aquatic 

Metabolism Half-life (days)

420 Combined parent, 

quizalofop-acid, and 

bound residues2

MRID 

00146697

Hydrolysis Half-lives (days) Stable (pH 7) Combined parent and 

quizalofop-acid 

residues2

MRID 

00131583

Aqueous Photolysis

Half-life (days)

85.4 days Combined parent and 

quizalofop-acid2

MRID 

00146693

1LUIS Report. 1/6/2012. Quizalofop-p-ethyl (128709).

2The TTR approach sums residues of concern at each time point in each of the fate studies and fits degradation 

curves through this residue sum. These comments indicate the residues summed for each study.

Aquatic Exposure Modeling Results

The aquatic EECs for the various scenarios and application methods are listed in Table 5. 

For some uses, the maximum seasonal application rate was not an integer multiple of the 

maximum individual application rate. Table 6 provides additional detail indicating how the 

maximum seasonal application rate was distributed between the individual applications. 

The Agency has developed only a limited number of model scenarios. Some of the scenarios 

used to model a particular use are from regions outside of the geographic restrictions for that 

use. In these cases, EECs will necessarily be more uncertain than in those cases in which the 

scenario locations and geographic use restrictions better align.

Two scenarios require further clarification. First, EFED does not currently have a suitable 

scenario (or surrogate scenario) for applications to pineapple. To provide a high-end estimate 

of potential exposure from applications to pineapple, the Mississippi cotton scenario was 

selected because it has a meteorological file associated with it that is representative of areas 

with high amounts of rainfall. Hawaii and Puerto Rico receive large amounts of rain; rainfall 

is a driving force in the generation of EECs.
43

The second scenario in need of further clarification is the paved area scenario. EFED’s 

understanding of this scenario is that paved areas would be sprayed to control weeds that 

would be growing in the cracks in the pavement. The EECs calculated are for a completely 

paved watershed draining into the standard pond. The EEC can be linearly scaled to the 

proportion of the watershed that is paved. For example, if 10% of the watershed is paved, 

then the appropriate exposure values are 10% of the values provided under the paved areas 

entry in Table 5 (see sample model output in Appendix G).

Table 5. Aquatic quizalofop-p-ethyl EEC values

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Peak 21-day 

average

60-day 

average

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production

2 apps @ 0.0834 lb ai/A (7-day interval)

Alfalfa

(MN alfalfa OP)

A

G

3.2439

2.3641

3.1591

2.2989

3.0262

2.2357

Carrot

(CA Row Crop RLF)

A

G

2.9219

2.3906

2.8308

2.3066

2.7275

2.1727

Chinese cabbage

(CA Cole Crop RLF)

A

G

6.5102

5.9816

6.3749

5.8582

6.1363

5.6347

Garlic

(CA Garlic RLF)

A

G

3.1903

2.5178

3.1109

2.4413

2.9776

2.3342

Onion and Radish

(CA onion W/irrig STD)

A

G

1.7975

1.1664

1.7556

1.1215

1.7089

1.057

Red beets

(CA Row Crop RLF)

A

G

2.9219

2.3906

2.8308

2.3066

2.7275

2.1727

Spinach

(CA lettuce STD)

A

G

4.7683

4.1377

4.6423

4.0219

4.5518

3.9295

Swiss chard

(CA lettuce STD)

A

G

4.7683

4.1377

4.6423

4.0219

4.5518

3.9295

All states, food item

2 apps @ 0.0834 lb ai/A (7-day interval)

Sugar beets

(CA sugar beet W/irrig OP)

A

G

1.7585

1.00725

1.7034

0.97215

1.6504

0.92407

Sugar beets

(MN sugar beet STD)

A

G

4.9319

4.1284

4.7972

4.0171

4.5858

3.8903
44

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Peak 21-day 

average

60-day 

average

Except New York

1 app at 0.0695 lb ai/A

Barley and Wheat

(CA Wheat RLF)

A

G

2.0586

1.7928

1.9951

1.7317

1.8964

1.6435

Barley and Wheat

(ND wheat STD)

A

G

2.1658

1.8393

2.0984

1.7886

2.0012

1.7234

Barley and Wheat

(OR wheat OP)

A

G

1.4209

1.1225

1.3929

1.1009

1.3693

1.0792

Barley and Wheat

(TX wheat OP)

A

G

2.0762

1.8911

2.0123

1.8305

1.8002

1.5982

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Canola/rape

(ND canola STD)

A

G

2.5532

1.9196

2.4777

1.8743

2.3773

1.7927

Crambe

(CA Row Crop RLF)

A

G

2.3499

1.8572

2.2986

1.8183

2.2133

1.758

Crambe

(MI beans STD)

A

G

3.962

3.422

3.8821

3.3373

3.7321

3.2005

Soybeans

(MS soybean STD)

A

G

6.8374

6.498

6.5753

6.2511

6.2246

5.9149

Sunflowers

(CA corn OP)

A

G

2.0317

1.6713

1.9878

1.651

1.9277

1.6096

Sunflowers

(IL Corn STD)

A

G

3.9877

3.5359

3.8931

3.4455

3.8193

3.3792

Sunflowers

(IN Corn Std)

A

G

3.2332

2.8219

3.1178

2.7235

3.0022

2.6291

Sunflowers

(KS Corn Std)

A

G

5.8264

5.4552

5.7292

5.3695

5.554

5.204

Sunflowers

(MS corn STD)

A

G

5.5477

5.2201

5.3746

5.0559

5.2468

4.9238

Sunflowers

(NC corn E STD)

A

G

2.4737

1.9695

2.409

1.9062

2.2865

1.8052

Sunflowers

(NC corn W OP)

A

G

4.6154

4.1596

4.4916

4.0464

4.3731

3.9362

Sunflowers

(ND corn OP)

A

G

3.7274

3.1419

3.6242

3.0556

3.5196

2.988
45

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Peak 21-day 

average

60-day 

average

Sunflowers

(OH Corn STD)

A

G

4.1211

3.6426

3.9882

3.5189

3.7995

3.3558

Sunflowers

(PA corn STD)

A

G

3.4193

2.8912

3.3448

2.8137

3.2278

2.7128

Sunflowers

(TX corn OP)

A

G

4.7586

4.4377

4.6189

4.3101

4.4175

4.1261

1 app at 0.0834 lb ai/A

Field Corn

(CA corn OP)

A

G

1.3485

1.0866

1.3184

1.074

1.2708

1.04658

Field Corn

(IL Corn STD)

A

G

2.5371

2.2367

2.4861

2.1826

2.4345

2.1387

Field Corn

(IN Corn Std)

A

G

2.002

1.6963

1.9378

1.6881

1.8533

1.6329

Field Corn

(KS Corn Std)

A

G

3.9031

3.6589

3.8406

3.6041

3.6753

3.4161

Field Corn

(MS corn STD)

A

G

3.6028

3.3847

3.5287

3.2985

3.4206

3.2057

Field Corn

(NC corn E STD)

A

G

1.7521

1.3971

1.6936

1.346

1.6334

1.3045

Field Corn

(NC corn W OP)

A

G

2.9839

2.6822

2.8907

2.5947

2.8026

2.5098

Field Corn

(ND corn OP)

A

G

2.4124

2.0243

2.3455

1.9684

2.2785

1.9213

Field Corn

(OH Corn STD)

A

G

2.5186

2.1711

2.4386

2.1024

2.3673

2.0508

Field Corn

(PA corn STD)

A

G

2.1426

1.8389

2.0767

1.7764

2.01

1.6904

Field Corn

(TX corn OP)

A

G

2.9889

2.7755

2.8942

2.677

2.7204

2.5142

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Sorghum

(TXsorghumOP)

A

G

6.102

5.7445

5.9538

5.6002

5.6358

5.3044

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Cotton

(CA cotton W/irrig STD)

A

G

1.1651

0.57519

1.1303

0.56616

1.0876

0.54549
46

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Peak 21-day 

average

60-day 

average

Cotton

(MS cotton STD)

A

G

5.0259

4.646

4.8656

4.4933

4.6414

4.2777

Cotton

(NC cotton STD)

A

G

5.1579

4.7392

5.0175

4.6114

4.8381

4.4581

Cotton

(TX cotton OP)

A

G

4.184

3.8324

4.083

3.7307

3.8877

3.5516

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Dry beans

(CA Row Crop RLF)

A

G

3.4743

2.8456

3.3538

2.7449

3.1636

2.5842

Dry beans

(MI beans STD)

A

G

6.0823

5.2971

5.9518

5.1838

5.8049

5.0563

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Dry and succulent peas and

lentils (CA Row Crop RLF)

A

G

1.9447

1.5878

1.9058

1.5563

1.8241

1.4925

Snap beans

(CA Row Crop RLF)

A

G

3.0984

2.5369

2.9924

2.4472

2.863

2.3062

Snap beans

(MI beans STD)

A

G

5.4748

4.7557

5.3693

4.6575

5.1845

4.5155

Texas, Oklahoma, Kansas, and Colorado, only

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Fallow

(CA Turf RLF)

A

G

2.7513

1.9472

2.6784

1.9236

2.6034

1.8834

2 apps at 0.0834 lb ai/A (7-days)

Flax

(CA Row Crop RLF)

A

G

2.9219

2.3906

2.8308

2.3066

2.7275

2.1727

Garbanzos (including chick 

peas) (CA Row Crop RLF)

A

G

2.9219

2.3906

2.8308

2.3066

2.7275

2.1727

Garbanzos (including chick 

peas) (MI beans STD)

A

G

5.168

4.4906

5.083

4.4037

4.9093

4.265

Maine and Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Hybrid cottonwood/poplar 

plantations

(PA apple STD V2)

A

G

2.9575

2.2796

2.8853

2.2243

2.8009

2.1669

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)
47

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Peak 21-day 

average

60-day 

average

Mint (spearmint and 

peppermint)

(CA lettuce STD)

A

G

5.8014

5.176

5.6622

4.9992

5.4516

4.7857

2 apps at 0.111 lb ai/A (7-days)

Non-crop areas 

(uncultivated areas, fence 

rows, roadsides, equipment 

storage areas, and other 

similar areas)

(CA right-of-way RLF)

A

G

6.9661

6.3427

6.8076

6.1987

6.2444

5.7362

Non-crop areas

(CA Turf RLF)

A

G

3.0643

2.1487

2.988

2.0988

2.9062

2.0586

Non-crop areas

(FL turf STD)

A

G

1.5729

0.68379

1.5197

0.65138

1.4449

0.6071

Non-crop areas

(PA turf STD)

A

G

2.4248

1.2399

2.3779

1.2116

2.2869

1.1741

Puerto Rico (pineapple only) and Hawaii, only

2 apps at 0.208 lb ai/A (7-days)

Ornamental and/or shade 

trees (CA nursery STD)

A

G

4.3858

2.5917

4.2487

2.5068

4.1297

2.4053

Pineapple

(MS cotton STD)

A

G

19.073

17.804

18.664

17.371

18.185

16.934

1 app at 0.108 lb ai/A

Paved areas (private 

roads/sidewalks)

(CA Impervious RLF)

A

G

19.649

19.959

19.207

19.516

18.327

18.624

Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Perennial ryegrass grown 

for seed (ND wheat STD)

A

G

4.4857

3.8345

4.335

3.7289

4.1339

3.5787

RLF = red legged frog

OP = organophosphate

STD = standard
48

Terrestrial Exposure

Dietary-Based Quizalofop-P-Ethyl Residue Levels

The Agency uses the T-REX model (v1.5, USEPA, Mar. 22, 2012) to estimate the terrestrial 

animal exposure values resulting from possible dietary ingestion of quizalofop-p-ethyl 

residues on vegetative matter and insects present on non-food and food crops from exposure 

to quizalofop-p-ethyl. It is assumed that the degradates from quizalofop-p-ethyl are 

equivalent in their toxicity and this automatically incorporated into the model. In all 

screening-level assessments, the organisms are assumed to consume 100% of their diet as 

one food type. This model incorporates the Kenaga nomograph, as modified by Fletcher et 

al. (1994), which is based on a large set of actual field residue data. The upper limit values 

from the nomograph represented the 95th percentile of residue values from actual field 

measurements (Hoerger and Kenaga, 1972). The Terrestrial Residue Exposure Model 

version 1.5 (T-REX) was employed to estimate (1) EECs for different food items for birds 

and mammals, (2) dose/diet based risk to birds as well as dose based risk to mammals, and 

(3) EECs for small and large insects to estimate risk to terrestrial invertebrates from direct 

contact. The short grass EECs were used to evaluate risk from acute oral exposure for 

terrestrial invertebrates (Table 6). 

Results of the T-REX v1.5 modeling of quizalofop-p-ethyl residue levels on those dietary 

food items which potentially occur on some treated fields, for mammals and birds4are 

provided in Tables 7 and 8. Residue levels for dietary items were calculated for all foliage 

spray applications.

Results include dietary-based values (i.e., milligrams of quizalofop-p-ethyl per kilogram of 

diet (mg/kg-diet)), and both an upper-bound and mean estimate of these exposure levels. The 

upper-bound values are derived using the upper-bound Kenaga nomogram which used the 

highest of the highest normalized residue values from a number of studies, as a tolerance 

limit approach.

As birds are also used as a surrogate for reptiles and terrestrial-phase amphibians within this 

assessment, it is assumed that dose-based exposure levels for these animals are the same as 

birds (i.e., food ingestion rate per body weight for a bird is the same as for an amphibian and 

reptile). However, reptiles and amphibians have a lower ingestion rate for a given body 

weight than birds (US EPA, 1993). Therefore, the dose-based EECs presented here represent 

an overestimate of exposure for reptiles and amphibians of a given body size (see sample 

output in Appendix I).

 

4 Birds are also used as a surrogate for reptiles and terrestrial-phase amphibians.
49

Table 6. T-REX modeling scenarios

Use Maximum 

Application Rate 

(lb ai/A)

Number of 

Applications 

(Interval between 

Applications, days)

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese 

cabbage, garlic, onion, radish, red beets, spinach, Swiss 

chard

All states, food item: sugar beets

0.0834 2 

(7-days)

Except New York

Barley, wheat

0.0695 1

Canola/rape, crambe, soybeans, sunflowers 0.0834 1 at 0.0834 and

1 at 0.042

(7-days)

Field corn seed production (herbicide-tolerant) 0.0834 1

Sorghum (herbicide-tolerant) 0.0834 1 at 0.0834 and

1 at 0.057

(7-days)

Cotton 0.034 3 at 0.034 and

1 at 0.023

(7-days)

Dry beans 0.0834 2 at 0.0834 and

1 at 0.03

(7-days)

Dry and succulent peas, lentils, snap beans 0.0834 1 at 0.0834 and

1 at 0.01

(7-days)

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

0.0834 2 at 0.0834 and 

1 at 0.04

(7-days)

Flax, garbanzos (including chick peas) 0.0834 2

(7-days)
50

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

0.0695 2

2

(7-days)

Mint (spearmint and peppermint) 0.0834 2 at 0.0834 and

1 at 0.04

Non-crop areas (uncultivated areas, fence rows, roadsides, 

equipment storage areas, and other similar areas)

0.111 2

2

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

0.208 2

(7-days)

Paved areas (private roads/sidewalks) 0.108 1

3

Minnesota, only

Perennial ryegrass grown for seed

0.0695 2

(7-days)

Parameters used in T-REX Model: Foliar half life = 35 days; Avian NOAEC – 180 mg ai/kg-diet (mallard

duck)1; Mammal LD50 = 870 mg ai/kg-bw (rat); Mammal NOEL = 5 mg ai/kg-bw (rat)

1

Surrogate data from fenoxaprop-ethyl because quizalofop-p-ethyl NOAEC was non-definitive (< 269 mg 

ai/kg-diet.

2Assuming two applications at the highest rate for the seasonal maximum.

3Assuming the seasonal maximum is equivalent to the single application rate

Table 7. Avian quizalofop-p-ethyl upper bound EEC values 

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(20 g)

Medium

(100 g)

Large

(1000 g)

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, radish, 

red beets, spinach, Swiss chard

All states, food item: sugar beets

2 apps at 0.0834 lb ai/A (7-day interval)

Short grass 37.44 42.64 24.32 10.89

Tall grass 17.16 19.54 11.14 4.99

Broadleaf plants 21.06 23.99 13.68 6.12

Fruits/pods 2.34 2.67 1.52 0.68

Arthropods 14.66 16.70 9.52 4.26

Seeds - 0.59 0.34 0.15

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A

Short grass 16.68 19.00 10.83 4.85

Tall grass 7.65 8.71 4.97 2.22
51

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(20 g)

Medium

(100 g)

Large

(1000 g)

Broadleaf plants 9.38 10.69 6.09 2.73

Fruits/pods 1.04 1.19 0.68 0.30

Arthropods 6.53 7.44 4.24 1.90

Seeds - 0.26 0.15 0.07

Canola/rape, crambe, soybeans, sunflowers

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Short grass 27.50 31.33 17.86 8.00

Tall grass 12.61 14.36 8.19 3.67

Broadleaf plants 15.47 17.62 10.05 4.50

Fruits/pods 1.72 1.96 1.12 0.50

Arthropods 10.77 12.27 7.00 3.13

Seeds - 0.44 0.25 0.11

Field corn seed production (herbicide-tolerant)

1 app at 0.0834 lb ai/A

Short grass 20.02 22.80 13.00 5.82

Tall grass 9.17 10.45 5.96 2.67

Broadleaf plants 11.26 12.82 7.31 3.27

Fruits/pods 1.25 1.42 0.81 0.36

Arthropods 7.84 8.93 5.09 2.28

Seeds - 0.32 0.18 0.08

Sorghum (herbicide-tolerant)

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Short grass 31.10 35.43 20.20 9.04

Tall grass 14.26 16.24 9.26 4.15

Broadleaf plants 17.50 19.93 11.36 5.09

Fruits/pods 1.94 2.21 1.26 0.57

Arthropods 12.18 13.87 7.91 3.54

Seeds - 0.49 0.28 0.13

Cotton

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Short grass 24.19 27.55 15.71 7.03

Tall grass 11.09 12.63 7.20 3.22

Broadleaf plants 13.61 15.50 8.84 3.96

Fruits/pods 1.51 1.72 0.98 0.44
52

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(20 g)

Medium

(100 g)

Large

(1000 g)

Arthropods 9.47 10.79 6.15 2.76

Seeds - 0.38 0.22 0.10

Dry beans

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Short grass 39.79 45.32 25.84 11.57

Tall grass 18.24 20.77 11.85 5.30

Broadleaf plants 22.38 25.49 14.54 6.51

Fruits/pods 2.49 2.83 1.62 0.72

Arthropods 15.59 17.75 10.12 4.53

Seeds - 0.63 0.36 0.16

Dry and succulent peas, lentils, snap beans

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Short grass 20.02 22.80 13.00 5.82

Tall grass 9.17 10.45 5.96 2.67

Broadleaf plants 11.26 12.82 7.31 3.27

Fruits/pods 1.25 1.42 0.81 0.36

Arthropods 7.84 8.93 5.09 2.28

Seeds - 0.32 0.18 0.08

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 42.19 48.06 27.40 12.27

Tall grass 19.34 22.03 12.56 5.62

Broadleaf plants 23.73 27.03 15.41 6.90

Fruits/pods 2.64 3.00 1.71 0.77

Arthropods 16.53 18.82 10.73 4.81

Seeds - 0.67 0.38 0.17

Flax, garbanzos (including chick peas)

2 apps at 0.0834 lb ai/A (7-days)

Short grass 37.44 42.64 24.32 10.89

Tall grass 17.16 19.54 11.14 4.99

Broadleaf plants 21.06 23.99 13.68 6.12

Fruits/pods 2.34 2.67 1.52 0.68

Arthropods 14.66 16.70 9.52 4.26
53

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(20 g)

Medium

(100 g)

Large

(1000 g)

Seeds - 0.59 0.34 0.15

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

2 apps at 0.0695 lb ai/A (7-days)

Short grass 31.20 35.53 20.26 9.07

Tall grass 14.30 16.29 9.29 4.16

Broadleaf plants 17.55 19.99 11.40 5.10

Fruits/pods 1.95 2.22 1.27 0.57

Arthropods 12.22 13.92 7.94 3.55

Seeds - 0.49 0.28 0.13

Mint (spearmint and peppermint)

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 42.19 48.06 27.40 12.27

Tall grass 19.34 22.03 12.56 5.62

Broadleaf plants 23.73 27.03 15.41 6.90

Fruits/pods 2.64 3.00 1.71 0.77

Arthropods 16.53 18.82 10.73 4.81

Seeds - 0.67 0.38 0.17

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, and 

other similar areas)

2 apps at 0.111 lb ai/A (7-days)

Short grass 49.83 56.75 32.36 14.49

Tall grass 22.84 26.01 14.83 6.64

Broadleaf plants 28.03 31.92 18.20 8.15

Fruits/pods 3.11 3.55 2.02 0.91

Arthropods 19.52 22.23 12.68 5.67

Seeds - 0.79 0.45 0.20

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

2 apps at 0.208 lb ai/A (7-days)

Short grass 93.38 106.35 60.64 27.15

Tall grass 42.80 48.74 27.80 12.44

Broadleaf plants 52.53 59.82 34.11 15.27

Fruits/pods 5.84 6.65 3.79 1.70
54

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(20 g)

Medium

(100 g)

Large

(1000 g)

Arthropods 36.57 41.65 23.75 10.63

Seeds - 1.48 0.84 0.38

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A

Short grass 25.92 29.52 16.83 7.54

Tall grass 11.88 13.53 7.72 3.45

Broadleaf plants 14.58 16.61 9.47 4.24

Fruits/pods 1.62 1.85 1.05 0.47

Arthropods 10.15 11.56 6.59 2.95

Seeds - 0.41 0.23 0.10

Minnesota, only

Perennial ryegrass grown for seed

2 apps at 0.0695 lb ai/A (7-days)

Short grass 31.20 35.53 20.26 9.07

Tall grass 14.30 16.29 9.29 4.16

Broadleaf plants 17.55 19.99 11.40 5.10

Fruits/pods 1.95 2.22 1.27 0.57

Arthropods 12.22 13.92 7.94 3.55

Seeds - 0.49 0.28 0.13

Table 8. Mammalian quizalofop-p-ethyl upper bound EEC values

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(15 g)

Medium

(135 g)

Large

(1000 g)

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, radish, 

red beets, spinach, Swiss chard

All states, food item: sugar beets

2 apps @ 0.0834 lb ai/A (7-day interval)

Short grass 37.44 35.70 24.67 5.72

Tall grass 17.16 16.36 11.31 2.62

Broadleaf plants 21.06 20.08 13.88 3.22

Fruits/pods 2.34 2.23 1.54 0.36
55

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(15 g)

Medium

(135 g)

Large

(1000 g)

Arthropods 14.66 13.98 9.66 2.24

Seeds - 0.50 0.34 0.08

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A

Short grass 16.68 15.90 10.99 2.55

Tall grass 7.65 7.29 5.04 1.17

Broadleaf plants 9.38 8.95 6.18 1.43

Fruits/pods 1.04 0.99 0.69 0.16

Arthropods 6.53 6.23 4.30 1.00

Seeds - 0.22 0.15 0.04

Canola/rape, crambe, soybeans, sunflowers

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Short grass 27.50 26.22 18.12 4.20

Tall grass 12.61 12.02 8.31 1.93

Broadleaf plants 15.47 14.75 10.19 2.36

Fruits/pods 1.72 1.64 1.13 0.26

Arthropods 10.77 10.27 7.10 1.65

Seeds - 0.36 0.25 0.06

Field corn seed production (herbicide-tolerant)

1 app at 0.0834 lb ai/A

Short grass 20.02 19.08 13.19 3.06

Tall grass 9.17 8.75 6.05 1.40

Broadleaf plants 11.26 10.73 7.42 1.72

Fruits/pods 1.25 1.19 0.82 0.19

Arthropods 7.84 7.47 5.17 1.20

Seeds - 0.27 0.18 0.04

Sorghum (herbicide-tolerant)

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Short grass 31.10 29.66 20.50 4.75

Tall grass 14.26 13.59 9.39 2.18

Broadleaf plants 17.50 16.68 11.53 2.67

Fruits/pods 1.94 1.85 1.28 0.30

Arthropods 12.18 11.62 8.03 1.86
56

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(15 g)

Medium

(135 g)

Large

(1000 g)

Seeds - 0.41 0.28 0.07

Cotton

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Short grass 24.19 23.06 15.94 3.70

Tall grass 11.09 10.57 7.31 1.69

Broadleaf plants 13.61 12.97 8.97 2.08

Fruits/pods 1.51 1.44 1.00 0.23

Arthropods 9.47 9.03 6.24 1.45

Seeds - 0.32 0.22 0.05

Dry beans

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Short grass 39.79 37.94 26.22 6.08

Tall grass 18.24 17.39 12.02 2.79

Broadleaf plants 22.38 21.34 14.75 3.42

Fruits/pods 2.49 2.37 1.64 0.38

Arthropods 15.59 14.86 10.27 2.38

Seeds - 0.53 0.36 0.08

Dry and succulent peas, lentils, snap beans

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Short grass 20.02 19.08 13.19 3.06

Tall grass 9.17 8.75 6.05 1.40

Broadleaf plants 11.26 10.73 7.42 1.72

Fruits/pods 1.25 1.19 0.82 0.19

Arthropods 7.84 7.47 5.17 1.20

Seeds - 0.27 0.18 0.04

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 42.19 40.23 27.80 6.45

Tall grass 19.34 18.44 12.74 2.95

Broadleaf plants 23.73 22.63 15.64 3.63

Fruits/pods 2.64 2.51 1.74 0.40

Arthropods 16.53 15.76 10.89 2.52

Seeds - 0.56 0.39 0.09
57

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(15 g)

Medium

(135 g)

Large

(1000 g)

Flax, garbanzos (including chick peas)

2 apps at 0.0834 lb ai/A (7-days)

Short grass 37.44 35.70 24.67 5.72

Tall grass 17.16 16.36 11.31 2.62

Broadleaf plants 21.06 20.08 13.88 3.22

Fruits/pods 2.34 2.23 1.54 0.36

Arthropods 14.66 13.98 9.66 2.24

Seeds - 0.50 0.34 0.08

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

2 apps at 0.0695 lb ai/A (7-days)

Short grass 31.20 29.75 20.56 4.77

Tall grass 14.30 13.63 9.42 2.18

Broadleaf plants 17.55 16.73 11.56 2.68

Fruits/pods 1.95 1.86 1.28 0.30

Arthropods 12.22 11.65 8.05 1.87

Seeds - 0.41 0.29 0.07

Mint (spearmint and peppermint)

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 42.19 40.23 27.80 6.45

Tall grass 19.34 18.44 12.74 2.95

Broadleaf plants 23.73 22.63 15.64 3.63

Fruits/pods 2.64 2.51 1.74 0.40

Arthropods 16.53 15.76 10.89 2.52

Seeds - 0.56 0.39 0.09

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, and 

other similar areas)

2 apps at 0.111 lb ai/A (7-days)

Short grass 49.83 47.51 32.84 7.61

Tall grass 22.84 21.78 15.05 3.49

Broadleaf plants 28.03 26.72 18.47 4.28

Fruits/pods 3.11 2.97 2.05 0.48

Arthropods 19.52 18.61 12.86 2.98

Seeds - 0.66 0.46 0.11
58

Feeding Category

Dietarybased EECs 

(mg/kg-food 

item)

Dose-based EECs (mg/kg-bw)

Small

(15 g)

Medium

(135 g)

Large

(1000 g)

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

2 apps at 0.208 lb ai/A (7-days)

Short grass 93.38 89.03 61.53 14.27

Tall grass 42.80 40.80 28.20 6.54

Broadleaf plants 52.53 50.08 34.61 8.02

Fruits/pods 5.84 5.56 3.85 0.89

Arthropods 36.57 34.87 24.10 5.59

Seeds - 1.24 0.85 0.20

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A

Short grass 25.92 24.71 17.08 3.96

Tall grass 11.88 11.33 7.83 1.82

Broadleaf plants 14.58 13.90 9.61 2.23

Fruits/pods 1.62 1.54 1.07 0.25

Arthropods 10.15 9.68 6.69 1.55

Seeds - 0.34 0.24 0.06

Minnesota, only

Perennial ryegrass grown for seed

2 apps at 0.0695 lb ai/A (7-days)

Short grass 31.20 29.75 20.56 4.77

Tall grass 14.30 13.63 9.42 2.18

Broadleaf plants 17.55 16.73 11.56 2.68

Fruits/pods 1.95 1.86 1.28 0.30

Arthropods 12.22 11.65 8.05 1.87

Seeds - 0.41 0.29 0.07

Off-Field Terrestrial and Wetland/Riparian Plant Quizalofop-P-Ethyl Exposure 

TerrPlant 1.2.2 (10/29/09) was used as a Tier 1 model for screening level assessments of 

pesticides. The model provides estimates of exposure to terrestrial plants from single 

pesticide applications; the model does not consider exposures to plants from multiple 

pesticide applications. TerrPlant derives pesticide EECs in runoff and in spray drift, and 

develops risk quotients for non-listed and listed species of monocots and dicots inhabiting 

dry and semi-aquatic areas. 
59

The estimated exposure concentrations of quizalofop-p-ethyl for terrestrial plants are 

presented below (Table 9). The most protective ground and aerial application scenarios for 

each use were selected, based on information from the label (see Appendix H for sample 

output). 

Table 9. Terrestrial plant exposure concentration estimates for quizalofop-p-ethyl

Description Equation

EEC (lb ai/A)

Ground Aerial

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, 

radish, red beets, spinach, Swiss chard

1 app at 0.0834 lb ai/A

Runoff to dry areas (A/I)*R 0.000834 0.000834

Runoff to semi-aquatic areas (A/I)*R*10 0.00834 0.00834

Spray drift A*D 0.000834 0.00417

Total for dry areas ((A/I)*R)+(A*D) 0.001668 0.005004

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.009174 0.01251

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A

Runoff to dry areas (A/I)*R 0.000695 0.000695

Runoff to semi-aquatic areas (A/I)*R*10 0.00695 0.00695

Spray drift A*D 0.000695 0.003475

Total for dry areas ((A/I)*R)+(A*D) 0.00139 0.00417

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.007645 0.010425

Canola/rape, crambe, soybeans, sunflowers, field corn seed production (herbicidetolerant), sorghum (herbicide-tolerant), dry beans, dry and succulent peas, lentils, snap 

beans, flax, garbanzos (including chick peas), mint (peppermint and spearmint), sugar 

beet

1 app at 0.0834

Runoff to dry areas (A/I)*R 0.000834 0.000834

Runoff to semi-aquatic areas (A/I)*R*10 0.00834 0.00834

Spray drift A*D 0.000834 0.00417

Total for dry areas ((A/I)*R)+(A*D) 0.001668 0.005004

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.009174 0.01251

Cotton

1 app at 0.034

Runoff to dry areas (A/I)*R 0.00034 0.00034

Runoff to semi-aquatic areas (A/I)*R*10 0.0034 0.0034
60

Description Equation

EEC (lb ai/A)

Ground Aerial

Spray drift A*D 0.00034 0.0017

Total for dry areas ((A/I)*R)+(A*D) 0.00068 0.00204

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.00374 0.0051

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

1 app at 0.0834

Runoff to dry areas (A/I)*R 0.000834 0.000834

Runoff to semi-aquatic areas (A/I)*R*10 0.00834 0.00834

Spray drift A*D 0.000834 0.00417

Total for dry areas ((A/I)*R)+(A*D) 0.001668 0.005004

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.009174 0.01251

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

1 app at 0.0695 lb ai/A

Runoff to dry areas (A/I)*R 0.000695 0.000695

Runoff to semi-aquatic areas (A/I)*R*10 0.00695 0.00695

Spray drift A*D 0.000695 0.003475

Total for dry areas ((A/I)*R)+(A*D) 0.00139 0.00417

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.007645 0.010425

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, 

and other similar areas)

1 app at 0.111 lb ai/A

Runoff to dry areas (A/I)*R 0.00111 0.00111

Runoff to semi-aquatic areas (A/I)*R*10 0.0111 0.0111

Spray drift A*D 0.00111 0.00555

Total for dry areas ((A/I)*R)+(A*D) 0.00222 0.00666

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.01221 0.01665

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

1 app at 0.208 lb ai/A

Runoff to dry areas (A/I)*R 0.00208 0.00208

Runoff to semi-aquatic areas (A/I)*R*10 0.0208 0.0208

Spray drift A*D 0.00208 0.0104

Total for dry areas ((A/I)*R)+(A*D) 0.00416 0.01248

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.02288 0.0312

Paved areas (private roads/sidewalks)
61

Description Equation

EEC (lb ai/A)

Ground Aerial

1 app at 0.108 lb ai/A

Runoff to dry areas (A/I)*R 0.00108 0.00108

Runoff to semi-aquatic areas (A/I)*R*10 0.0108 0.0108

Spray drift A*D 0.00108 0.0054

Total for dry areas ((A/I)*R)+(A*D) 0.00216 0.00648

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.01188 0.0162

Minnesota, only

Perennial ryegrass grown for seed

1 app at 0.0695 lb ai/A

Runoff to dry areas (A/I)*R 0.000695 0.000695

Runoff to semi-aquatic areas (A/I)*R*10 0.00695 0.00695

Spray drift A*D 0.000695 0.003475

Total for dry areas ((A/I)*R)+(A*D) 0.00139 0.00417

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.007645 0.010425

A = application rate

I = incorporation

R = runoff fraction

D = drift fraction
Chapter 3 Effects Characterization

62

Effects Characterization

There are two enantiomers for quizalofop. Quizalofop-p-ethyl is the R-enantiomer and the 

isomer with pesticidal properties. Quizalofop-ethyl is a 50/50 racemic mixture of R- and Senantiomers. Toxicity information has been submitted for both enantiomers. Given that the 

toxicity of quizalofop-ethyl is driven by the R-enantiomer in the mixture, the lowest toxicity 

endpoint for an organism was used in the assessment, regardless of the chemical tested 

(quizalofop-p-ethyl or quizalofop-ethyl).

Many quizalofop-p-ethyl toxicity studies were submitted by the registrant since the 

Registration Review Quizalofop Final Work Plan (US EPA, 2008) and have been 

incorporated into the chemical’s toxicity profile. Of particular note are the studies that were 

requested in the DCI: vegetative vigor, seedling emergence, non-vascular aquatic plant, and 

a special aquatic monocot study with rice. The aquatic monocot and non-vascular plant 

studies were classified as “acceptable” and filled data gaps in the ecotoxicological risk 

picture. Several seedling emergence and vegetative vigor studies were submitted and 

classified as “supplemental” or “acceptable.” Combined, they complete the risk picture for 

terrestrial plants. 

No additional information was available from the open literature. The toxicity endpoints of 

the registrant-submitted studies were lower than those found in the open literature and there 

were not any open literature studies that addressed taxa not currently considered with the 

Agency-required data. A list of the quizalofop-p-ethyl open literature studies that were 

screened as part of this assessment is provided in Appendix D.

One data gap remains for quizalofop-p-ethyl – acute toxicity to estuarine/marine fish. In 

addition, there are several instances where the lowest toxicity endpoint is non-definitive 

(acute and chronic avian toxicity, and algal toxicity). In these instances, surrogate data from 

the structurally-similar chemicals fenoxaprop-p-ethyl and fenoxaprop-ethyl were considered. 

Finally, an acute-to-chronic ratio was employed to derive a chronic NOAEC for the most 

sensitive (on an acute-basis) species of freshwater fish. A summary of the quizalofop studies 

and surrogate data used in this risk assessment are described below.

Terrestrial Vertebrate Toxicology

Effects on Birds

There was one acute avian oral toxicity study with quizalofop-ethyl (MRID 00128210). The 

study was classified as “supplemental” because it tested the common quail in lieu of the 

bobwhite quail and there was uncertainty about the weight-measured doses received by the 

birds. The acute oral LD50 of quizalofop-ethyl was reported as >2000 mg/kg-bw in the 

mallard duck and common quail. The toxicity value is non-definitive and was compared to 
Chapter 3 Effects Characterization

63

toxicity values for fenoxaprop-p-ethyl and fenoxaprop-ethyl, two herbicides with similar 

chemical structures to quizalofop. The reported LD50s for these chemicals were similar to 

quizalofop-ethyl (LD50 > 2000 and 2510 mg ai/kg-bw, fenoxaprop-p-ethyl and fenoxapropethyl, respectively). Sublethal effects included a decrease in food consumption and body 

weight. A passerine bird study was not available; thus the most sensitive mallard duck and 

common quail toxicity data will be used instead (Table 10).

Two dietary studies were available for quizalofop-ethyl. MRID 00128211 determined the 

LC50 to be > 5000 mg ai/kg-diet for both the bobwhite quail and mallard duck. Decreases in 

food consumption and weight loss were observed. Similarly, MRID 00147574 studied the 

bobwhite quail and yielded an LC50 of > 5620 mg ai/kg-diet. Weight loss was observed. 

Together, the acute oral dose and dietary studies indicate that quizalofop is practically nontoxic on an acute basis to birds (Table 10). 

There were two avian chronic studies available. Quizalofop-p-ethyl was found to be more 

toxic to the mallard duck (NOAEC < 269 mg ai/kg-diet) compared to the bobwhite quail 

(NOAEC = 1030 mg ai/kg-diet). The mallard duck’s NOAEC is based on the proportion of 

eggs set. No adult parameters were affected; however a reduction in hatchability (31%), 

percent of eggs laid and set, and 14-day old survivors was noted in the 1030 mg ai/kg-diet 

treatment group. Hatchling weight also decreased by 5% at this treatment level. No 

sublethal effects were observed in the bobwhite quail study. Both studies were classified as 

“supplemental” because they did not verify the frozen storage stability of quizalofop-p-ethyl 

feed mixtures that had been prepared in advance, frozen, and then thawed for use. In 

addition, the non-definitive (less than) value of the mallard’s toxicity endpoint lends 

uncertainty to estimating the true toxicity of quizalofop-p-ethyl. To decrease this

uncertainty, the mallard NOAECs for fenoxaprop-p-ethyl and fenoxaprop-ethyl, two 

structurally-similar herbicides to quizalofop-p-ethyl, were examined. Fenoxaprop-p-ethyl 

yielded a NOAEC of 512 mg ai/kg-diet whereas the NOAEC for fenoxaprop-ethyl was 180 

mg ai/kg-diet. Both of these values are similar to the quizalofop-p-ethyl NOAEC; it was 

determined that using the fenoxaprop-ethyl NOAEC of 180 mg ai/kg-diet would be a 

conservative definitive number to use in the risk assessment (Table 10).

Effects on Mammals

An acute oral mammal toxicity study yielded LD50s of 870 and 1088 mg ai/kg-bw for female 

and male rats, respectively (MRID 41206105). Quizalofop-ethyl was assigned a toxicity 

class of “slightly toxic”, based on these data. No sublethal effects were reported (Table 10). 

A two-generation rat reproduction study yielded a NOAEC of 5 mg ai/kg-bw and a LOAEC 

of 20 mg ai/kg-bw. At 20 mg ai/kg-bw, there was a reduction in live pup births for both the 

F1 and F2 generations. Clinical observations of the offspring revealed an increase in the 
Chapter 3 Effects Characterization

64

incidence of hematomas, but it was not a dose-responsive effect. Decreases in pup body 

weight were also observed at the LOAEC. Specifically, there were decreases in the weight 

of the liver, kidney, heart, and spleen (Table 10). 

Table 10. Summary of specific measurement endpoint values selected to evaluate risk 

for birds and mammal assessment endpoints

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity

and Effect(s)

Chemical / 

Source / 

Study 

Classification

Survival and 

Reproduction of 

Birds, Reptiles 

and Amphibians

Mortality: acute oral 

avian LD50

Mallard duck 

(Anas 

platyrhynchos)

Common quail 

(Coturnix 

coturnix)

LD50 > 2000 mg ai/kg-bw 

NOAEL < 500 mg ai/kg-bw

Decrease in food consumption and weight 

gain.

Quizalofop-ethyl 

technical grade, % 

purity not reported

MRID 00128210

Supplemental

Mortality: subacute 

avian LC50

Mallard duck 

(Anas 

platyrhynchos)

Bobwhite quail 

(Colinus 

virginianus) 

8-day LC50 > 5,000 mg ai/kg-diet 

Decrease in food consumption and weight 

gain.

Quizalofop-ethyl 

technical grade, % 

purity not reported

MRID 00128211 

Acceptable

Mortality: subacute 

avian LC50

Bobwhite quail 

(Colinus 

virginianus)

8-day LC50 > 5620 mg ai/kg-diet

NOAEC = 3160 mg ai/kg-diet

Decrease in weight gain.

Quizalofop-ethyl 

technical grade, 

99% ai

MRID 00147574

Acceptable

Reproduction: 

chronic 

reproduction 

NOAEC

Mallard duck 

(Anas 

platyrhynchos) 

NOAEC = <269 mg ai/kg-diet

LOAEC = 269 mg ai/kg-diet

The most sensitive parameter was a reduction 

in the proportion of eggs set.

Other effects included a reduction in 

hatchability, percent of eggs laid and set, 14-

day old survivors, and weight in the 1030 mg 

ai/kg-diet groups.

Quizalofop-p-ethyl 

technical grade, 

98.4%

MRID 46607102

Supplemental

Reproduction: 

chronic 

reproduction 

NOAEC

Bobwhite quail 

(Colinus 

virginianus)

NOAEC = 1030 mg ai/kg-diet

LOAEC = >1030 mg ai/kg-diet

No effects.

Quizalofop-p-ethyl 

technical grade 

98.4% ai

MRID 4660701

Supplemental
Chapter 3 Effects Characterization

65

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity

and Effect(s)

Chemical / 

Source / 

Study 

Classification

Survival and 

Reproduction of 

Mammals

Mortality: acute oral 

LD50

Rat (Rattus 

norvegicus)

Female LD50 = 870 mg ai/kg-bw

Male LD50 = 1088 mg ai/kg-bw

Unsteady gait, loss of righting reflex, 

piloerection, coma, hypothermia, respiratory 

stress, and urinary incontinence appeared after 

1-hour of dosing.

Quizalofop-ethyl 

technical grade, 97 

% 

MRID 41206105

Acceptable

Reproduction: 

chronic 

reproduction 

NOAEC

Rat (Rattus 

norvegicus)

NOAEC = 100 mg/kg-diet (5 mg/kg-bw)

(2 generation reproduction study)

LOAEC = 400 mg/kg-diet (20 mg/kg-bw)

Decreases in male and female pup body weight

and reduced number of live pup births in F1

and F2 generations.

Quizalofop-ethyl 

technical grade, 

99.1%

MRID 00153351

Acceptable

Terrestrial Invertebrate Toxicology

There was one acute contact toxicity study available for the honeybee (Table 11). The LD50

was > 50 μg ai/bee, which classifies quizalofop-ethyl as “practically non-toxic” to bees. No 

sublethal effects were observed and there were two mortalities (one in the lowest dose group 

and one in the highest dose group), that were considered incidental. The study was classified 

as “supplemental” because raw data were not included with the submission to verify the 

study’s results. 

Table 11. Summary of specific measurement endpoint values selected to evaluate risk 

for honey bees

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity,

and Effect(s) (μg ai/bee)

Chemical / 

Source / 

Acute Contact 

Toxicity

Mortality: acute 

contact LD50

Honey Bee 

(Apis mellifera)

LD50 > 50

No effects.

Quizalofop-ethyl 

technical grade, 

99.1%

MRID 00150942

Supplemental
Chapter 3 Effects Characterization

66

Aquatic Vertebrate (Fish) Toxicology

Effects to Freshwater Fish and Aquatic-Phase Amphibians

Data from seven studies are available for acute effects of quizalofop-p-ethyl and quizalofopethyl to warm and cold water species of freshwater fish. The most sensitive endpoint (LC50 = 

0.21 mg ai/L (MRID 47408413) was derived from a rainbow trout study that used a 

quizalofop-p-ethyl typical end-use product. Endpoints from aquatic studies that use a typical 

end-use product are not used for risk quotient calculations; therefore, MRID 47408402 was 

used instead with its LC50 of 0.72 mg ai/L for the rainbow trout. Sub-lethal effects (e.g., 

quiescence, sounding, weak, ceased swimming, loss of balance, dark discoloration and 

irregular respiration) were documented. Based on this toxicity value, quizalofop-p-ethyl is 

classified as “highly toxic” on an acute basis to freshwater fish. In addition to the two 

rainbow trout studies already described, there were three other studies performed with 

rainbow trout, which yielded toxicity endpoints that were higher (quizalofop-p-ethyl – MRID 

47408405; quizalofop-ethyl – MRIDs 00128207, 00146680). Two bluegill sunfish studies 

were available (MRIDs 00128207, 00128208), both conducted with quizalofop-ethyl. 

Toxicity values ranged from < 0.46 to < 0.28 mg ai/L (Table 12).

Chronic data were available from an early-life stage study with the fathead minnow (MRID 

00150109). The most sensitive endpoints were length and wet weight. Length was reduced 

by 10% at the LOAEC (0.030 mg ai/L) and weight by 18%. Larval survival was affected at 

the highest dose level (0.157 mg ai/L). Chronic data were not available for the rainbow trout, 

the most sensitive acute toxicity species. In these circumstances, an acute-to-chronic ratio 

(ACR) is calculated using the relationship between the acute and chronic toxicity endpoints 

for a pair of species. In the case of quizalofop, chronic data were only available for the 

fathead minnow and there was not an acute study available for this species. Instead, 

freshwater fish data for fenoxaprop-p-ethyl, a structurally similar chemical, were considered 

to derive a NOAEC for the rainbow trout with quizalofop-p-ethyl. In general, the 

fenoxaprop-p-ethyl acute toxicity data for rainbow trout was slightly more sensitive than that 

for quizalofop (quizalofop-p-ethyl LC50 = 0.72 mg ai/L compared with fenoxaprop-p-ethyl 

LC50 = 0.46 mg ai/L). Thus the use of fenoxaprop-p-ethyl data to derive the ACR was 

considered reasonable and protective. The chronic quizalofop-p-ethyl NOAEC was derived 

as follows:

LC50(fenox. fathead) = LC50 (quiz. trout) = 0.466 = 0.72 = 0.068 = NOAEC(quiz. trout)

NOAEC(fenox. fathead) NOAEC(quiz. trout) 0.044 X

However, when the ACR-derived NOAEC for rainbow trout was compared with the NOAEC 

from the quizalofop fathead minnow study, it was found to be more sensitive (0.010 mg 

ai/L). Consequently, the fathead minnow NOAEC was used in the risk assessment for risk 

quotient calculations.
Chapter 3 Effects Characterization

67

Effects to Estuarine-Marine Fish

There were no estuarine/marine fish acute toxicity data available for quizalofop. To fill the 

data gap, toxicity information from fenoxaprop-p-ethyl and fenoxaprop-ethyl (two 

structurally similar chemicals) were examined. Neither chemical had an appropriate set of 

acute and chronic toxicity information for estuarine/marine fish that could be used to derive 

an ACR. Fenoxaprop-ethyl was the only chemical with an acute estuarine/marine value. Its 

LC50 was less toxic than the most sensitive value for freshwater fish. It was assumed that this 

same toxicity relationship would hold true for quizalofop-p-ethyl; thus it was considered 

protective and appropriate to use the quizalofop-p-ethyl acute toxicity value for rainbow trout 

as a surrogate for an estuarine/marine fish LC50 (Table 12).

One study is available for the chronic effects of quizalofop-p-ethyl to estuarine/marine fish 

(MRID 47910503). The endpoints are based on effects to larval survival and hatchability. 

No treatment-related effects were detected for time to hatch, but larval survival was affected 

in the 0.167 mg ai/L treatment group. The study was classified as “supplemental” because 

the solvent appeared to promote growth in fish. The hatchability and survival endpoints were 

not affected by the solvent, thus only these endpoints are considered valid for consideration 

in the risk assessment. The effect of quizalofop-p-ethyl on the growth of estuarine/marine 

fish remains uncertain, although based on the results of the chronic freshwater fish study, a 

decrease in growth could be expected (Table 12).
Chapter 3 Effects Characterization

68

Table 12. Summary of specific measurement endpoint values selected to evaluate risk 

for fish and amphibian assessment endpoints

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity,

and Effect(s) (mg ai/L)

Chemical/

Source /

Study

Classification

Survival and 

reproduction of 

freshwater fish

Acute mortality: 

most sensitive acute 

freshwater fish 96-

hour LC50

Rainbow trout 

(Oncorhynchus 

mykiss)

96-hour LC50 = 0.72 

Quiescence, sounding, 

weakness, swimming cessation, 

loss of balance, dark 

discoloration, and irregular 

respiration.

Quizalofop-p-ethyl

MRID 47408402 

Acceptable

Chronic Early Life 

Stage:

most sensitive 

NOAEC

Fathead minnow 

(Pimphales 

promelas)

NOAEC = 0.010

LOAEC = 0.030

Decreased length and weight, 

and larval mortality.

Quizalofop-p-ethyl

MRID 00150109

Acceptable

Rainbow trout 

(Oncorhynchus 

mykiss)

Acute-to-Chronic Ratio

NOAEC = 0.068

Fenoxaprop-p-ethyl

MRIDs 48417901, 

48492501

Survival and 

reproduction of 

estuarine/marine 

fish

Acute mortality: 

most sensitive acute 

estuarine/marine 

fish 96-hour LC50

N/A

Rainbow trout 

(Oncorhynchus 

mykiss) data used 

instead

48-hour LC50 = 0.72 Quizalofop-p-ethyl

MRID 47408402 

Acceptable

Chronic Early Life 

Stage: most 

sensitive NOAEC

Sheepshead 

minnow 

(Cyprinodon 

variegatus)

NOAEC = 0.083

Survival, decreased larval size, 

and larval lethargy

Quizalofop-p-ethyl

MRID 47910503

Supplemental

Aquatic Invertebrate Toxicology

Effects to Freshwater Invertebrates

Information is available for four acute toxicity studies conducted using D. magna – two with 

quizalofop-p-ethyl and two with quizalofop-ethyl. The lowest toxicity endpoint was 

generated by MRID 47408410. The EC50 was 0.35 mg ai/L, and sublethal effects (slow 

swimming and lying on the bottom of the test vessel) were observed at the 0.28 and 0.51 mg 

ai/L treatment levels. The study was classified as “supplemental” because it did not provide 

measured concentrations for all of the treatment solutions; however, the toxicity values are 

considered reliable because the quizalofop-p-ethyl recovery concentrations in the chambers 

that were tested were within acceptable limits (86% to 113%). The two studies with 
Chapter 3 Effects Characterization

69

quizalofop-ethyl (MRIDs 00128109, 00146951) were classified as “supplemental” because 

precipitate was observed in the test solutions. Measured samples were not centrifuged before 

quantitation, thus there is uncertainty surrounding the EC50 values (2.12 and 6.4 mg ai/L). 

Finally, MRID 47408407 was classified as “acceptable,” but yielded a much less toxic value 

(EC50 = 51.9 mg ai/L). Sublethal effects were confined to one daphnid floating in the 11.8 

and 22.9 mg ai/L treatment groups. Together, these studies classify quizalofop as “slightly 

toxic to highly toxic” (Table 13).

Two chronic freshwater invertebrate studies were available for quizalofop-p-ethyl. Both 

studies were scientifically sound, but classified as “supplemental” because they did not 

measure certain chronic endpoints (MRID 47408409 – growth; MRID 47910501 – growth, 

time to first brood, and offspring immobility). Consequently, it is possible that one of these 

endpoints (growth, in particular, since neither study measured it) could be the most sensitive 

endpoint. Both studies found that parental survival was the most sensitive endpoint. Effects 

were also noted in the number of offspring per adult; there was a 34% reduction in offspring 

at 72-74 mg ai/L (Table 13).

Effects to Estuarine-Marine Invertebrates

Three studies examined the acute effects of quizalofop-p-ethyl (MRID 40242204) and 

quizalofop-ethyl (MRIDs 40242205, 40242207) on estuarine/marine invertebrates. All of the 

studies were classified as “supplemental” – the two shrimp studies because of uncertainty 

regarding the rate of hydrolysis of the test compound and the oyster study because of 

observations of precipitate in the diluter chamber. The LC50s from the studies produced a 

tight range of 0.15 to 0.25 mg ai/L. The most sensitive endpoint for these studies was 

mortality; sublethal effects were not observed for either the shrimp or the oyster. All three 

studies classify quizalofop as “highly toxic” to estuarine/marine invertebrates on an acute 

basis (Table 13).

Estuarine/marine invertebrate chronic toxicity data were not available. A toxicity value can 

be estimated based on the assumption that the acute-to-chronic ratio (ACR) for freshwater 

invertebrates applies to estuarine/marine invertebrates also. Thus, the following equation 

was used to estimate a NOAEC for mysid shrimp, the most sensitive estuarine/marine species 

on an acute basis (Table 13).

LC50(mysid) = EC50 (waterflea) = 0.15 = 0.35 = 0.34 = NOAEC(mysid)

NOAEC(mysid) NOAEC(waterflea) X 0.787
Chapter 3 Effects Characterization

70

Table 13. Summary of specific measurement endpoint values selected to evaluate risk 

for aquatic invertebrate assessment endpoints

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity,

and Effect(s) (mg ai/L)

Chemical/

Source /

Study

Classification

Survival and 

reproduction of 

freshwater 

invertebrates

Acute mortality: 

most sensitive acute 

freshwater 

invertebrate 48-hour 

EC50

Water flea (D. 

magna)

48-hour EC50 = 0.35

Slow swimming, lying on the bottom of 

the test chamber

Quizalofop-p-ethyl, 

technical grade, 

5.07%

MRID 47408410

Supplemental

Chronic effects: 

most sensitive 

NOAEC

Water flea (D. 

magna)

NOAEC = 26.6

Parental mortality

Quizalofop-p-ethyl, 

technical grade, 

96.9%

MRID 4740809

Supplemental

Survival and 

reproduction of 

estuarine/marine 

invertebrates

Acute mortality: 

most sensitive 

estuarine/marine 

invertebrate 96-hour 

EC50

Mysid shrimp 

(Americamysis 

bahia)

EC50 = 0.15

Mortality

Quizalofop-p-ethyl, 

technical grade, 

99.1%

MRID 40242204

Supplemental

Acute growth: most 

sensitive 

estuarine/marine 

invertebrate 96-hour 

EC50

Eastern oyster 

(Crassostrea 

virginianus)

EC50 = 0.19*

Shell growth

Quizalofop-ethyl, 

technical grade, 

99.1%

MRID 40242207

Supplemental

Chronic effects: 

most sensitive 

NOAEC

Mysid shrimp 

(Americamysis 

bahia)

Acute-to-Chronic Ratio

NOAEC = 0.34

Quizalofop-p-ethyl, 

technical grade, 5.07-

99.1%.

MRIDs 47408410, 

40242204, 4740809

Supplemental

*Used in the Risk Description section of the assessment.

Terrestrial Plant Toxicology

Several plant studies were available for quizalofop typical end-use products (quizalofop-pethyl – MRIDs 48038101, 47910505, 48038102; quizalofop-ethyl – MRIDs 47408411, 

47408412); only the most sensitive endpoints are presented in Table 14. MRID 47910505 
Chapter 3 Effects Characterization

71

yielded the most sensitive vegetative vigor endpoints. Wheat was the most sensitive 

monocot, based on dry weight. Similarly, dry weight was the most sensitive parameter in 

dicots (cucumber). Plant height was also affected in both the cucumber and wheat. Signs of 

phytotoxicity included: necrosis, chlorosis, and leaf curl. 

For seedling emergence, MRID 4708411 presented the lowest monocot endpoints. Fresh 

weight in corn (23-78% reduction) and oat (3-35%) was the most sensitive parameter. 

Seedling inhibition and survival ranged from -3 to 12% in treated plants compared to the 

controls. Some phytotoxic effects were also observed (chlorosis, necrosis, and growth 

reduction). The study was classified as “supplemental” because it only tested three monocot 

species whereas the guidelines require data on four species.

MRID 4708411 also presented the most sensitive toxicity data for dicot seedling emergence; 

however, the values were non-definitive. Given that no effects were observed in the species 

tested, the other seedling emergence study (MRID 48038101) was considered. This study 

tested higher concentrations of quizalofop; however, it also reached a non-definitive EC25

and based its NOAEC on the highest concentration tested. The study was classified 

supplemental in part because only four species of dicots were tested instead of six (including 

soybean, which is a required species). Given that no effects were seen and that quizalofop is 

an herbicide that targets monocots, the less sensitive toxicity values will be used in the risk 

assessment as it is believed that they more accurately reflect the true toxicity of quizalofop 

on dicots.
Chapter 3 Effects Characterization

72

Table 14. Summary of specific measurement endpoint values selected to evaluate risk 

for terrestrial plant assessment endpoints

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity,

and Effect(s) (lb ai/A)

Chemical/

Source /

Study

Classification

Effects to 

terrestrial plants

Vegetative vigor: 

dicot EC25 and 

NOAEC 

Cucumber 

(Cucumis sativa)

EC25 = 0.0931

NOAEC = 0.0477

Dry weight.

Quizalofop-p-ethyl 

typical end-use 

product, 10.13%

MRID 47910505

Acceptable

Vegetative vigor: 

monocot EC25 and 

NOAEC

Wheat (Triticum 

aestivum)

EC25 = 0.00146

NOAEC = 0.000791

Dry weight.

Quizalofop-p-ethyl 

typical end-use 

product, 10.13%

MRID 47910505

Acceptable

Effects to 

terrestrial plants

Seedling 

emergence: dicot 

EC25 and NOAEC

Cabbage (Brassica 

oleracea), carrot 

(Daucus carota), 

cucumber

(Cucumis sativa), 

soybean (Glycine 

max), sunflower 

(Helianthus 

annuus), cotton 

(Gossypium 

hirsutum), and flax 

(Linum 

usitatissimum)

EC25 > 0.086

NOAEC = 0.086

None.

Quizalofop-ethyl 

typical end-use 

product, 5.07%

MRID 47408411

Supplemental

Seedling 

emergence: dicot 

EC25 and NOAEC 

Cabbage (Brassica 

oleracea), 

sunflower 

(Helianthus 

annuus), carrot 

(Daucus carota), 

cucumber 

(Cucumis sativa)

EC25 > 0.127

NOAEC = 0.127

Quizalofop-p-ethyl 

typical end-use 

product, 5%

MRID 48038101

Supplemental

Seedling 

emergence: 

monocot EC25 and 

NOAEC

Corn (Zea mays) EC25 = 0.019

NOAEC = 0.0096

Fresh weight

Quizalofop-ethyl 

typical end-use 

product, 5.07%

MRID 47408411

Supplemental
Chapter 3 Effects Characterization

73

Aquatic Plant Toxicology

Aquatic plant toxicity data (Table 15) are available for quizalofop-p-ethyl from five studies 

(green algae – 2; freshwater diatom – 1; blue-green algae – 1; and estuarine/marine diatom –

1). A limit test (Tier 1) with a freshwater diatom showed 3.66% inhibition at 0.098 mg ai/L 

(MRID 43270901). Four Tier 2 studies were available for quizalofop-p-ethyl, given that it is 

an herbicide. Three of these studies yielded non-definitive (greater than) toxicity values; the 

EC50s ranged from > 0.082 to > 1.09 mg ai/L (MRIDs 48041401, 43235602, 43270902). No 

effects were documented in these studies and it was believed that the non-definitive values 

were much more conservative than a definitive value would be. To justify the use of a less 

sensitive endpoint, non-vascular plant studies from two structurally similar chemicals 

(fenoxaprop-p-ethyl and fenoxaprop-ethyl) were considered. These chemicals showed a 

similar trend – non-definitive toxicity values at low test concentrations and definitive 

numbers at higher test concentrations. In addition, the fenoxaprop toxicity values were 

within the same order of magnitude as the quizalofop values. The European Footprint 

database5reported a toxicity value (EC50 = 23 μg ai/L) that was lower than the most sensitive 

definitive toxicity value for algae (4100 μg ai/L). This value could not be used in this risk 

assessment because the Agency did not have access to the original study for an independent 

evaluation. Although substantially lower, the 23 μg ai/L does not result in a risk quotient 

above the LOC for non-vascular plants. Thus, it was determined that using the definitive 

quizalofop-p-ethyl toxicity value was a reasonable approach. 

The most sensitive definitive quizalofop-p-ethyl value was from a green algae study. The 

EC50 of 41 mg ai/L was based on a reduction in cell density. Biomass and growth rate were 

also affected. The study was classified as “supplemental” because the duration of the study 

was 72 hours (per OECD guidelines). A 96-hour value would likely be only slightly more 

sensitive than a 72 hour EC50 (MRID 48037501).

Two studies with quizalofop-p-ethyl were available for non-vascular plants. A special study 

(MRID 48356801) on a monocot aquatic plant (rice) was requested because quizalofop-pethyl is an herbicide that primarily targets monocots. This study yielded the most sensitive 

EC50 of 34.5 μg ai/L for dry weight. Number of leaves per plant, number of tillers per plant, 

and plant height also were affected (EC50s = 41, 58, and 66 μg ai/L, respectively). Other 

effects included chlorosis, necrosis, leaf curl, and mortality. A duckweed study (MRID 

48037504) was also available, but was considered incomplete because of a solvent effect in 

frond development and frond growth rate; these endpoints were not useable. In this study, 

frond biomass was the most sensitive parameter (consistent with the rice study); however, the 

EC50 was much higher (>658 μg ai/L). The greater sensitivity of aquatic monocots to 

quizalofop compared to dicots parallels the pattern seen in terrestrial plants (Table 15). 

 

5

http://sitem.herts.ac.uk/aeru/footprint/en/index.htm
Chapter 3 Effects Characterization

74

Table 15. Summary of specific measurement endpoint values selected to calculate risk 

quotient values to evaluate risk for aquatic plant assessment endpoints

Assessment

Endpoint

Measurement

Endpoint

Selected Measurement Endpoint Value and Source

Species Endpoint, Toxicity,

and Effect(s) (μg ai/L)

Chemical/

Source /

Study

Classification

Survival and 

biomass of 

aquatic vascular 

and non-vascular 

plants

Non-vascular species: the 

most sensitive productivity 

EC50 

Green algae 

(Selenastrum 

capricornutum)

72-hour EC50 = 41000

Cell density

Quizalofop-p-ethyl, 

technical grade, 

95.9%

MRID 48037501

Supplemental

Vascular species: 

endpoints based on 

mortality EC50

Rice (Oryza 

sativa)

EC50 = 34.5

Dry weight

Quizalofop-p-ethyl, 

typical end-use 

product, 10.4%

MRID 48356801

Acceptable
75

Results: Risk Characterization

Risk Estimation

As described in the Quizalofop-P-Ethyl Work Plan, estimates of exposure and ecotoxicity of 

quizalofop-p-ethyl are integrated using standard risk quotient (RQ) methods to evaluate the 

potential for adverse ecological effects to mammalian, avian, and other non-target species. 

Risk quotient results for non-target terrestrial and aquatic animals and plants are described in 

this section. Risk quotient results in this case represent expected direct effects to organisms 

(i.e. effects from direct toxicity to quizalofop-p-ethyl exposure) in contrast to indirect effects 

to an organism resulting from a modification of a resource such as loss of their prey or 

habitat.

Direct Effects to Non-Target Terrestrial Vertebrates

DIRECT EFFECTS TO BIRDS, REPTILES, AND (LAND-PHASE) AMPHIBIANS

Risk quotients were not calculated for acute dose-based or acute dietary-based risks because 

all of the toxicity data were non-definitive. Risks from these potential exposure pathways are 

evaluated and discussed in the Risk Description Section. 

Chronic dietary risk quotients were calculated with T-REX for the maximum usage rates of 

quizalofop-p-ethyl for all uses (Table 16). Risk quotients ranged from 0.01 to 0.52; no uses 

yielded risk quotients that exceeded the chronic LOC of 1.

Table 16. Upper bound chronic dietary-based risk quotients for birds derived from TREX 

Risk Quotients Based on Kenaga Upper 

Bound EEC

Chronic Dietary-Based Risk Quotients

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, 

radish, red beets, spinach, Swiss chard

All states, food item: sugar beets

2 apps at 0.0834 lb ai/A (7-day interval)

Short grass 0.21

Tall grass 0.10

Broadleaf plants 0.12

Fruits/pods/seeds 0.01

Arthropods 0.08

Except New York

Barley, wheat
76

Risk Quotients Based on Kenaga Upper 

Bound EEC

Chronic Dietary-Based Risk Quotients

1 app at 0.0695 lb ai/A

Short grass 0.09

Tall grass 0.04

Broadleaf plants 0.05

Fruits/pods/seeds 0.01

Arthropods 0.04

Canola/rape, crambe, soybeans, sunflowers

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Short grass 0.15

Tall grass 0.07

Broadleaf plants 0.09

Fruits/pods/seeds 0.01

Arthropods 0.06

Field corn seed production (herbicide-tolerant)

1 app at 0.0834 lb ai/A

Short grass 0.11

Tall grass 0.05

Broadleaf plants 0.06

Fruits/pods/seeds 0.01

Arthropods 0.04

Sorghum (herbicide-tolerant)

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Short grass 0.17

Tall grass 0.08

Broadleaf plants 0.10

Fruits/pods/seeds 0.01

Arthropods 0.07

Cotton

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Short grass 0.13

Tall grass 0.06

Broadleaf plants 0.08

Fruits/pods/seeds 0.01

Arthropods 0.05

Dry beans

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)
77

Risk Quotients Based on Kenaga Upper 

Bound EEC

Chronic Dietary-Based Risk Quotients

Short grass 0.22

Tall grass 0.10

Broadleaf plants 0.12

Fruits/pods/seeds 0.01

Arthropods 0.09

Dry and succulent peas, lentils, snap beans

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Short grass 0.11

Tall grass 0.05

Broadleaf plants 0.06

Fruits/pods/seeds 0.01

Arthropods 0.04

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 0.23

Tall grass 0.11

Broadleaf plants 0.13

Fruits/pods/seeds 0.01

Arthropods 0.09

Flax, garbanzos (including chick peas)

2 apps at 0.0834 lb ai/A (7-days)

Short grass 0.21

Tall grass 0.10

Broadleaf plants 0.12

Fruits/pods/seeds 0.01

Arthropods 0.08

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

2 apps at 0.0695 lb ai/A (7-days)

Short grass 0.17

Tall grass 0.08

Broadleaf plants 0.10

Fruits/pods/seeds 0.01

Arthropods 0.07

Mint (spearmint and peppermint)
78

Risk Quotients Based on Kenaga Upper 

Bound EEC

Chronic Dietary-Based Risk Quotients

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 0.23

Tall grass 0.11

Broadleaf plants 0.13

Fruits/pods/seeds 0.01

Arthropods 0.09

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, and

other similar areas)

2 apps at 0.111 lb ai/A (7-days)

Short grass 0.28

Tall grass 0.13

Broadleaf plants 0.16

Fruits/pods/seeds 0.02

Arthropods 0.11

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

2 apps at 0.208 lb ai/A (7-days)

Short grass 0.52

Tall grass 0.24

Broadleaf plants 0.29

Fruits/pods/seeds 0.03

Arthropods 0.20

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A

Short grass 0.14

Tall grass 0.07

Broadleaf plants 0.08

Fruits/pods/seeds 0.01

Arthropods 0.06

Minnesota, only

Perennial ryegrass grown for seed

2 apps at 0.0695 lb ai/A (7-days)

Short grass 0.17

Tall grass 0.08

Broadleaf plants 0.10

Fruits/pods/seeds 0.01
79

Risk Quotients Based on Kenaga Upper 

Bound EEC

Chronic Dietary-Based Risk Quotients

Arthropods 0.07

No scenarios exceeded the chronic LOC of 1.

DIRECT EFFECTS TO MAMMALS 

Acute Effects

Acute dose-based risk quotients were calculated for the maximum application rates for all 

quizalofop-p-ethyl uses (Table 17). Risk quotients ranged from < 0.01 to 0.05; none of the 

uses produced risk quotients that exceeded the acute listed species LOC of 0.1.

Chronic Effects

Chronic dose-based risk quotients ranged from 0.01 to 8.10 (Table 17). All uses exceeded 

the LOC (1) for small and medium-sized mammals consuming diets of short grass. Most 

uses exceeded the LOC for large mammals and/or additional food items in the small and 

medium-sized mammal classes as well. Risk quotients for mammals consuming fruits, pods, 

or seeds never exceeded the LOC of 1. Chronic dietary-based risk quotients were also 

calculated. These ranged from 0.01 to 0.93; none of the uses produced risk quotients that 

exceeded the LOC of 1.

Table 17. Dietary upper bound risk quotients for mammals 

Risk Quotients 

Based

on Kenaga

Upper Bound EEC

Dose-Based RQs Chronic 

DietaryBased RQs

15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, radish, red 

beets, spinach, Swiss chard

All states, food item: sugar beets

2 apps at 0.0834 lb ai/A (7-day interval)

Short grass 0.02 3.25*** 0.02 2.77*** 0.01 1.49*** 0.37

Tall grass 0.01 1.49*** 0.01 1.27*** <0.01 0.68 0.17

Broadleaf plants 0.01 1.83*** 0.01 1.56*** <0.01 0.84 0.21

Fruits/pods <0.01 0.20 <0.01 0.17 <0.01 0.09 0.02

Arthropods 0.01 1.27*** 0.01 1.09*** <0.01 0.58 0.15

Seeds <0.01 0.05 <0.01 0.04 <0.01 0.02 0.02

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A
80

Risk Quotients 

Based

on Kenaga

Upper Bound EEC

Dose-Based RQs Chronic 

DietaryBased RQs

15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Short grass 0.01 1.45*** 0.01 1.24*** <0.01 0.66 0.17

Tall grass <0.01 0.66 <0.01 0.57 <0.01 0.30 0.08

Broadleaf plants <0.01 0.81 <0.01 0.70 <0.01 0.37 0.09

Fruits/pods <0.01 0.09 <0.01 0.08 <0.01 0.04 0.01

Arthropods <0.01 0.57 <0.01 0.48 <0.01 0.26 0.07

Seeds <0.01 0.02 <0.01 0.02 <0.01 0.01 0.01

Canola/rape, crambe, soybeans, sunflowers

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Short grass 0.01 2.39*** 0.01 2.04*** 0.01 1.09*** 0.28

Tall grass 0.01 1.09*** 0.01 0.93 <0.01 0.50 0.13

Broadleaf plants 0.01 1.34*** 0.01 1.15*** <0.01 0.61 0.15

Fruits/pods <0.01 0.15 <0.01 0.13 <0.01 0.07 0.02

Arthropods 0.01 0.93 <0.01 0.80 <0.01 0.43 0.11

Seeds <0.01 0.03 <0.01 0.03 <0.01 0.02 0.02

Field corn seed production (herbicide-tolerant)

1 app at 0.0834 lb ai/A

Short grass 0.01 1.74*** 0.01 1.48*** <0.01 0.80 0.20

Tall grass <0.01 0.80 <0.01 0.68 <0.01 0.36 0.09

Broadleaf plants 0.01 0.98 <0.01 0.83 <0.01 0.45 0.11

Fruits/pods <0.01 0.11 <0.01 0.09 <0.01 0.05 0.01

Arthropods <0.01 0.68 <0.01 0.58 <0.01 0.31 0.08

Seeds <0.01 0.02 <0.01 0.02 <0.01 0.01 0.01

Sorghum (herbicide-tolerant)

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Short grass 0.02 2.70*** 0.01 2.31*** 0.01 1.24*** 0.31

Tall grass 0.01 1.24*** 0.01 1.06*** <0.01 0.57 0.14

Broadleaf plants 0.01 1.52*** 0.01 1.30*** <0.01 0.70 0.17

Fruits/pods <0.01 0.17 <0.01 0.14 <0.01 0.08 0.02

Arthropods <0.01 1.06*** 0.01 0.90 <0.01 0.48 0.12

Seeds <0.01 0.04 <0.01 0.03 <0.01 0.02 0.02

Cotton

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Short grass 0.01 2.10*** 0.01 1.79*** 0.01 0.96 0.24

Tall grass 0.01 0.96 <0.01 0.82 <0.01 0.44 0.11
81

Risk Quotients 

Based

on Kenaga

Upper Bound EEC

Dose-Based RQs Chronic 

DietaryBased RQs

15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Broadleaf plants 0.01 1.18*** 0.01 1.01*** <0.01 0.54 0.14

Fruits/pods <0.01 0.13 <0.01 0.11 <0.01 0.06 0.02

Arthropods <0.01 0.82 <0.01 0.70 <0.01 0.38 0.09

Seeds <0.01 0.03 <0.01 0.02 <0.01 0.01 0.02

Dry beans

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Short grass 0.02 3.45*** 0.02 2.95*** 0.01 1.58*** 0.40

Tall grass 0.01 1.58*** 0.01 1.35*** <0.01 0.72 0.18

Broadleaf plants 0.01 1.94*** 0.01 1.66*** 0.01 0.89 0.22

Fruits/pods <0.01 0.22 <0.01 0.18 <0.01 0.10 0.02

Arthropods 0.01 1.35*** 0.01 1.16*** <0.01 0.62 0.16

Seeds <0.01 0.05 <0.01 0.04 <0.01 0.02 0.02

Dry and succulent peas, lentils, snap beans

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Short grass 0.01 1.74*** 0.01 1.48*** <0.01 0.80 0.20

Tall grass <0.01 0.80 <0.01 0.68 <0.01 0.36 0.09

Broadleaf plants 0.01 0.98 <0.01 0.83 <0.01 0.45 0.11

Fruits/pods <0.01 0.11 <0.01 0.09 <0.01 0.05 0.01

Arthropods <0.01 0.68 <0.01 0.58 <0.01 0.31 0.08

Seeds <0.01 0.02 <0.01 0.02 <0.01 0.01 0.01

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 0.02 3.66*** 0.02 3.13*** 0.01 1.68*** 0.42

Tall grass 0.01 1.68*** 0.01 1.43*** <0.01 0.77 0.19

Broadleaf plants 0.01 2.06*** 0.01 1.76*** 0.01 0.94 0.24

Fruits/pods <0.01 0.23 <0.01 0.20 <0.01 0.10 0.03

Arthropods 0.01 1.43*** 0.01 1.22*** <0.01 0.66 0.17

Seeds <0.01 0.05 <0.01 0.04 <0.01 0.02 0.03

Flax, garbanzos (including chick peas)

2 apps at 0.0834 lb ai/A (7-days)

Short grass 0.02 3.25*** 0.02 2.77*** 0.01 1.49*** 0.37

Tall grass 0.01 1.49*** 0.01 1.27*** <0.01 0.68 0.17

Broadleaf plants 0.01 1.83*** 0.01 1.56*** <0.01 0.84 0.21
82

Risk Quotients 

Based

on Kenaga

Upper Bound EEC

Dose-Based RQs Chronic 

DietaryBased RQs

15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Fruits/pods <0.01 0.20 <0.01 0.17 <0.01 0.09 0.02

Arthropods 0.01 1.27*** 0.01 1.09*** <0.01 0.58 0.15

Seeds <0.01 0.05 <0.01 0.04 <0.01 0.02 0.02

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

2 apps at 0.0695 lb ai/A (7-days)

Short grass 0.02 2.71*** 0.01 2.31*** 0.01 1.24*** 0.31

Tall grass 0.01 1.24*** 0.01 1.06*** <0.01 0.57 0.14

Broadleaf plants 0.01 1.52*** 0.01 1.30*** <0.01 0.70 0.18

Fruits/pods <0.01 0.17 <0.01 0.14 <0.01 0.08 0.02

Arthropods 0.01 1.06*** 0.01 0.91 <0.01 0.49 0.12

Seeds <0.01 0.04 <0.01 0.03 <0.01 0.02 0.02

Mint (spearmint and peppermint)

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Short grass 0.02 3.66*** 0.02 3.13*** 0.01 1.68*** 0.42

Tall grass 0.01 1.68*** 0.01 1.43*** <0.01 0.77 0.19

Broadleaf plants 0.01 2.06*** 0.01 1.76*** 0.01 0.94 0.24

Fruits/pods <0.01 0.23 <0.01 0.20 <0.01 0.10 0.03

Arthropods 0.01 1.43*** 0.01 1.22*** <0.01 0.66 0.17

Seeds <0.01 0.05 <0.01 0.04 <0.01 0.02 0.03

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, and other 

similar areas)

2 apps at 0.111 lb ai/A (7-days)

Short grass 0.02 4.32*** 0.02 3.69*** 0.01 1.98*** 0.50

Tall grass 0.01 1.98*** 0.01 1.69*** 0.01 0.91 0.23

Broadleaf plants 0.01 2.43*** 0.01 2.08*** 0.01 1.11*** 0.28

Fruits/pods 0.00 0.27 0.00 0.23 0.00 0.12 0.03

Arthropods 0.01 1.69*** 0.01 1.45*** 0.00 0.78 0.20

Seeds 0.00 0.06 0.00 0.05 0.00 0.03 0.03

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

2 apps at 0.208 lb ai/A (7-days)

Short grass 0.05 8.10*** 0.04 6.92*** 0.02 3.71*** 0.93

Tall grass 0.02 3.71*** 0.02 3.17*** 0.01 1.70*** 0.43
83

Risk Quotients 

Based

on Kenaga

Upper Bound EEC

Dose-Based RQs Chronic 

DietaryBased RQs

15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Broadleaf plants 0.03 4.56*** 0.02 3.89*** 0.01 2.09*** 0.53

Fruits/pods <0.01 0.51 <0.01 0.43 <0.01 0.23 0.06

Arthropods 0.02 3.17*** 0.02 2.71*** 0.01 1.45*** 0.37

Seeds <0.01 0.11 <0.01 0.10 <0.01 0.05 0.06

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A

Short grass 0.01 2.25*** 0.01 1.92*** 0.01 1.03*** 0.26

Tall grass 0.01 1.03*** 0.01 0.88 <0.01 0.47 0.12

Broadleaf plants 0.01 1.26*** 0.01 1.08*** <0.01 0.58 0.15

Fruits/pods <0.01 0.14 <0.01 0.12 <0.01 0.06 0.02

Arthropods 0.01 0.88 <0.01 0.75 <0.01 0.40 0.10

Seeds <0.01 0.03 <0.01 0.03 <0.01 0.01 0.02

Minnesota, only

Perennial ryegrass grown for seed

2 apps at 0.0695 lb ai/A (7-days)

Short grass 0.02 2.71*** 0.01 2.31*** 0.01 1.24*** 0.31

Tall grass 0.01 1.24*** 0.01 1.06*** <0.01 0.57 0.14

Broadleaf plants 0.01 1.52*** 0.01 1.30*** <0.01 0.70 0.18

Fruits/pods <0.01 0.17 <0.01 0.14 <0.01 0.08 0.02

Arthropods 0.01 1.06*** 0.01 0.91 <0.01 0.49 0.12

Seeds <0.01 0.04 <0.01 0.03 <0.01 0.02 0.02

Bold text indicates an LOC was exceeded.

* Exceeds the acute listed species LOC of 0.1

**Exceeds the acute non-listed species LOC of 0.5

***Exceeds the chronic LOC of 1

Direct Effects to Non-Target Terrestrial Invertebrates

Only non-definitive honeybee toxicity data were available for quizalofop-p-ethyl. Risk 

quotients cannot be calculated from non-definitive values. A qualitative description of the 

risk is available in the Risk Description Section of this document. 

Direct Effects to Terrestrial and Wetland/Riparian Plants

TerrPlant was used to model potential runoff and spray drift effects from the different 

quizalofop-p-ethyl uses (Table 18). The maximum application rate for each crop was used to 

calculate risk quotients for semi-aquatic and upland terrestrial plants. Insufficient data were 
84

available to calculate risk quotients for non-listed monocots; thus this group is discussed in 

the Risk Description Section.

Monocots were more sensitive than dicots. Ground application risk quotients ranged from < 

0.01 to 1.42 while aerial application risk quotients ranged from 0.11 to 13.15. All ground 

and aerial spray drift scenarios exceeded the LOC (1) for listed and non-listed monocots. 

Application rates of 0.0695 lb ai/A and higher yielded risk quotients that exceeded the LOCs 

in additional scenarios. Dicots did not exceed the LOC of 1 for any scenario. For ground 

applications, risk quotients ranged from < 0.01 to 0.18. For aerial applications, risk quotients 

ranged from 0.01 to 0.25.

Table 18. Summary of risk quotient values for plants in dry and semi-aquatic areas 

exposed to quizalofop-p-ethyl through runoff and spray drift

Plant 

Type

Listed 

Status

Dry Semi-Aquatic Spray Drift

Ground Aerial Ground Aerial Ground Aerial

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production: alfalfa, carrot, Chinese cabbage, garlic, onion, 

radish, red beets, spinach, Swiss chard

1 app at 0.0834 lb ai/A

Monocot non-listed <0.1 0.26 0.48 0.66 0.57 2.86*

Monocot listed 0.17 0.52 0.96 1.30* 1.05* 5.27*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A

Monocot non-listed <0.1 0.22 0.40 0.55 0.48 2.38*

Monocot listed 0.14 0.43 0.80 1.09* 0.88 4.39*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Canola/rape, crambe, soybeans, sunflowers, field corn seed production (herbicidetolerant), sorghum (herbicide-tolerant), dry beans, dry and succulent peas, lentils, snap 

beans, flax, garbanzos (including chick peas), mint (spearmint and peppermint), sugar 

beet

1 app at 0.0834

Monocot non-listed <0.1 0.26 0.48 0.66 0.57 2.86*

Monocot listed 0.17 0.52 0.96 1.30* 1.05* 5.27*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
85

Plant 

Type

Listed 

Status

Dry Semi-Aquatic Spray Drift

Ground Aerial Ground Aerial Ground Aerial

Cotton

1 app at 0.034

Monocot non-listed <0.1 0.11 0.20 0.27 0.23 1.16*

Monocot listed <0.1 0.21 0.39 0.53 0.43 2.15*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Texas, Oklahoma, Kansas, and Colorado, only

Fallow

1 app at 0.0834

Monocot non-listed <0.1 0.26 0.48 0.66 0.57 2.86*

Monocot listed 0.17 0.52 0.96 1.30* 1.05* 5.27*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

1 app at 0.0695 lb ai/A

Monocot non-listed <0.1 0.22 0.40 0.55 0.48 2.38*

Monocot listed 0.14 0.43 0.80 1.09* 0.88 4.39*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, 

and other similar areas)

1 app at 0.111 lb ai/A

Monocot non-listed 0.12 0.35 0.64 0.88 0.76 3.80*

Monocot listed 0.23 0.69 1.27* 1.73* 1.40* 7.02*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 0.13 <0.1 <0.1

Puerto Rico (pineapple only) and Hawaii, only

Ornamental and/or shade trees, pineapple

1 app at 0.208 lb ai/A

Monocot non-listed 0.22 0.66 1.20* 1.64* 1.42* 7.12*

Monocot listed 0.43 1.30* 2.38* 3.25* 2.63* 13.15*

Dicot non-listed N/A N/A N/A N/A <0.1 0.11

Dicot listed <0.1 <0.1 0.18 0.25 <0.1 <0.1

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A
86

Plant 

Type

Listed 

Status

Dry Semi-Aquatic Spray Drift

Ground Aerial Ground Aerial Ground Aerial

Monocot non-listed 0.11 0.34 0.63 0.85 0.74 3.70*

Monocot listed 0.23 0.68 1.24* 1.69* 1.37* 6.83*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 0.13 <0.1 <0.1

Minnesota, only

Perennial ryegrass grown for seed

1 app at 0.0695 lb ai/A

Monocot non-listed <0.1 0.22 0.40 0.55 0.48 2.38*

Monocot listed 0.14 0.43 0.80 1.09* 0.88 4.39*

Dicot non-listed N/A N/A N/A N/A <0.1 <0.1

Dicot listed <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

N/A – RQ could not be calculated because of a non-definitive EC25

Bold text indicates an LOC was exceeded.

*Exceeds LOC of 1.

Direct Effects to Freshwater Fish (Amphibians), Invertebrates and EstuarineMarine Fish (Amphibians) and Invertebrates, and Aquatic Plants

Risk quotients for aquatic organisms are calculated using aquatic EECs derived as described 

in the exposure analysis using PRZM/EXAMS in conjunction with selected acute and 

chronic fish, aquatic invertebrate, and aquatic plant toxicity values. The calculated risk 

quotients are based on total toxic residue exposure from the parent quizalofop-p-ethyl and its 

major degradates (quizalofop acid and 3-OH-quizalofop acid) for the aquatic environment.

Freshwater Fish and Aquatic-Phase Amphibians – Acute Risk

For freshwater fish (surrogate for aquatic-phase amphibians), acute risk quotients ranged 

from 0.001 to 0.028 and did not exceed the listed species acute LOC of 0.05 for any 

registered quizalofop-p-ethyl uses (Table 19). 

Freshwater Fish and Aquatic-Phase Amphibians – Chronic Risk

For freshwater fish (surrogate for aquatic-phase amphibians), chronic risk quotients ranged 

from 0.069 to 1.86. Two uses exceeded the chronic LOC (1): pineapple (ground and aerial), 

and paved areas (ground and aerial). All other quizalofop-p-ethyl uses were below the LOC 

of 1 (Table 19).

Estuarine/Marine Fish – Acute Risk
87

For estuarine/marine fish, acute risk quotients ranged from 0.001 to 0.028 and did not exceed 

the listed species acute LOC of 0.05 for any registered quizalofop-p-ethyl uses (Table 19). 

Estuarine/Marine Fish – Chronic Risk

For estuarine/marine fish, chronic risk quotients ranged from 0.007 to 0.224 and did not 

exceed the chronic LOC of 1 (Table 19). 

Table 19. Acute and chronic risks from quizalofop-p-ethyl to freshwater fish, 

estuarine/marine fish, and amphibians

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production

2 apps @ 0.0834 lb ai/A (7-day interval)

Alfalfa

(MN alfalfa OP)

A

G

0.005

0.003

0.303

0.223

0.005

0.003

0.037

0.027

Carrot

(CA Row Crop RLF)

A

G

0.004

0.003

0.273

0.217

0.004

0.003

0.033

0.026

Chinese cabbage

(CA Cole Crop RLF)

A

G

0.009

0.008

0.614

0.563

0.009

0.008

0.074

0.068

Garlic

(CA Garlic RLF)

A

G

0.004

0.004

0.298

0.233

0.004

0.004

0.036

0.028

Onion and Radish

(CA onion W/irrig

STD)

A

G

0.003

0.002

0.171

0.106

0.003

0.002

0.021

0.013

Red beets

(CA Row Crop RLF)

A

G

0.004

0.003

0.273

0.217

0.004

0.003

0.033

0.026

Spinach

(CA lettuce STD)

A

G

0.007

0.006

0.455

0.393

0.007

0.006

0.055

0.047

Swiss chard

(CA lettuce STD)

A

G

0.007

0.006

0.455

0.393

0.007

0.006

0.055

0.047

All states, food item

2 apps @ 0.0834 lb ai/A (7-day interval)
88

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Sugar beets

(CA sugar beet W/irrig

OP)

A

G

0.002

0.001

0.165

0.092

0.002

0.001

0.020

0.011

Sugar beets

(MN sugar beet STD)

A

G

0.007

0.006

0.459

0.389

0.007

0.006

0.055

0.047

Except New York

1 app at 0.0695 lb ai/A

Barley and Wheat

(CA Wheat RLF)

A

G

0.003

0.002

0.190

0.164

0.003

0.002

0.023

0.020

Barley and Wheat

(ND wheat STD)

A

G

0.003

0.003

0.200

0.172

0.003

0.003

0.024

0.021

Barley and Wheat

(OR wheat OP)

A

G

0.002

0.002

0.137

0.108

0.002

0.002

0.017

0.013

Barley and Wheat

(TX wheat OP)

A

G

0.003

0.003

0.180

0.160

0.003

0.003

0.022

0.019

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Canola/rape

(ND canola STD)

A

G

0.004

0.003

0.238

0.179

0.004

0.003

0.029

0.022

Crambe

(CA Row Crop RLF)

A

G

0.003

0.003

0.221

0.176

0.003

0.003

0.027

0.021

Crambe

(MI beans STD)

A

G

0.006

0.005

0.373

0.320

0.006

0.005

0.045

0.039

Soybeans

(MS soybean STD)

A

G

0.010

0.009

0.622

0.591

0.010

0.009

0.075

0.071

Sunflowers

(CA corn OP)

A

G

0.003

0.002

0.193

0.161

0.003

0.002

0.023

0.019

Sunflowers

(IL Corn STD)

A

G

0.006

0.005

0.382

0.338

0.006

0.005

0.046

0.041

Sunflowers

(IN Corn Std)

A

G

0.004

0.004

0.300

0.263

0.004

0.004

0.036

0.032

Sunflowers

(KS Corn Std)

A

G

0.008

0.008

0.555

0.520

0.008

0.008

0.067

0.063
89

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Sunflowers

(MS corn STD)

A

G

0.008

0.007

0.525

0.492

0.008

0.007

0.063

0.059

Sunflowers

(NC corn E STD)

A

G

0.003

0.003

0.229

0.181

0.003

0.003

0.028

0.022

Sunflowers

(NC corn W OP)

A

G

0.006

0.006

0.437

0.394

0.006

0.006

0.053

0.047

Sunflowers

(ND corn OP)

A

G

0.005

0.004

0.352

0.299

0.005

0.004

0.042

0.036

Sunflowers

(OH Corn STD)

A

G

0.006

0.005

0.380

0.336

0.006

0.005

0.046

0.040

Sunflowers

(PA corn STD)

A

G

0.005

0.004

0.323

0.271

0.005

0.004

0.039

0.033

Sunflowers

(TX corn OP)

A

G

0.007

0.006

0.442

0.413

0.007

0.006

0.053

0.050

1 app at 0.0834 lb ai/A

Field Corn

(CA corn OP)

A

G

0.002

0.002

0.127

0.105

0.002

0.002

0.015

0.013

Field Corn

(IL Corn STD)

A

G

0.004

0.003

0.243

0.214

0.004

0.003

0.030

0.026

Field Corn

(IN Corn Std)

A

G

0.003

0.002

0.185

0.163

0.003

0.002

0.022

0.020

Field Corn

(KS Corn Std)

A

G

0.005

0.005

0.368

0.342

0.005

0.005

0.044

0.041

Field Corn

(MS corn STD)

A

G

0.005

0.005

0.342

0.321

0.005

0.005

0.041

0.039

Field Corn

(NC corn E STD)

A

G

0.002

0.002

0.163

0.130

0.002

0.002

0.020

0.016

Field Corn

(NC corn W OP)

A

G

0.004

0.004

0.280

0.251

0.004

0.004

0.034

0.030

Field Corn

(ND corn OP)

A

G

0.003

0.003

0.228

0.192

0.003

0.003

0.027

0.023
90

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Field Corn

(OH Corn STD)

A

G

0.004

0.003

0.237

0.205

0.004

0.003

0.029

0.025

Field Corn

(PA corn STD)

A

G

0.003

0.003

0.201

0.169

0.003

0.003

0.024

0.020

Field Corn

(TX corn OP)

A

G

0.004

0.004

0.272

0.251

0.004

0.004

0.033

0.030

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Sorghum

(TXsorghumOP)

A

G

0.008

0.008

0.564

0.530

0.008

0.008

0.068

0.064

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Cotton

(CA cotton W/irrig

STD)

A

G

0.002

0.001

0.109

0.055

0.002

0.001

0.013

0.007

Cotton

(MS cotton STD)

A

G

0.007

0.006

0.464

0.428

0.007

0.006

0.056

0.052

Cotton

(NC cotton STD)

A

G

0.007

0.007

0.484

0.446

0.007

0.007

0.058

0.054

Cotton

(TX cotton OP)

A

G

0.006

0.005

0.389

0.355

0.006

0.005

0.047

0.043

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Dry beans

(CA Row Crop RLF)

A

G

0.005

0.004

0.316

0.258

0.005

0.004

0.038

0.031

Dry beans

(MI beans STD)

A

G

0.008

0.007

0.580

0.506

0.008

0.007

0.070

0.061

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Dry and succulent peas

and lentils (CA Row

Crop RLF)

A

G

0.003

0.002

0.182

0.149

0.003

0.002

0.022

0.018

Snap beans

(CA Row Crop RLF)

A

G

0.004

0.004

0.286

0.231

0.004

0.004

0.034

0.028

Snap beans

(MI beans STD)

A

G

0.008

0.007

0.518

0.452

0.008

0.007

0.062

0.054
91

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Texas, Oklahoma, Kansas, and Colorado, only

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Fallow

(CA Turf RLF)

A

G

0.004

0.003

0.260

0.188

0.004

0.003

0.031

0.023

2 apps at 0.0834 lb ai/A (7-days)

Flax

(CA Row Crop RLF)

A

G

0.004

0.003

0.273

0.217

0.004

0.003

0.033

0.026

Garbanzos (including 

chick peas) (CA Row 

Crop RLF)

A

G

0.004

0.003

0.273

0.217

0.004

0.003

0.033

0.026

Garbanzos (including 

chick peas) (MI beans 

STD)

A

G

0.007

0.006

0.508

0.440

0.007

0.006

0.059

0.051

Maine and Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Hybrid 

cottonwood/poplar 

plantations

(PA apple STD V2)

A

G

0.004

0.003

0.289

0.222 0.004

0.003

0.034

0.026

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Mint (spearmint and 

peppermint)

(CA lettuce STD)

A

G

0.008

0.007

0.566

0.500

0.008

0.007

0.066

0.058

2 apps at 0.111 lb ai/A (7-days)
92

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Non-crop areas 

(uncultivated areas, 

fence rows, roadsides, 

equipment storage 

areas, and other similar 

areas)

(CA right-of-way 

RLF)

A

G

0.010

0.009

0.624

0.574

0.010

0.009

0.075

0.069

Non-crop areas

(CA Turf RLF)

A

G

0.004

0.003

0.291

0.206

0.004

0.003

0.035

0.025

Non-crop areas

(FL turf STD)

A

G

0.002

0.001

0.144

0.061

0.002

0.001

0.017

0.007

Non-crop areas

(PA turf STD)

A

G

0.003

0.002

0.229

0.117

0.003

0.002

0.028

0.014

Puerto Rico (pineapple only) and Hawaii, only

2 apps at 0.208 lb ai/A (7-days)

Ornamental and/or 

shade trees (CA

nursery STD)

A

G

0.006

0.004

0.425

0.251

0.006

0.004

0.050

0.029

Pineapple

(MS cotton STD)

A

G

0.03

0.02

1.82***

1.70***

0.03

0.02

0.220

0.204

1 app at 0.108 lb ai/A

Paved areas (private 

roads/sidewalks)

(CA Impervious RLF)

A

G

0.027

0.028

1.83***

1.86***

0.027

0.028

0.220

0.224

Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Perennial ryegrass 

grown for seed (ND 

wheat STD)

A

G

0.006

0.005

0.413

0.358

0.006

0.005

0.500

0.431
93

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Fish Acute 

RQ (Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L1

Freshwater Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 10 μg 

ai/L2

Estuarine / 

Marine Fish 

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 720 μg 

ai/L

Estuarine / 

Marine Fish 

Chronic RQ 

(60-Day EEC/ 

NOAEC) 

NOAEC = 83 

μg ai/L

Bold text indicates an LOC was exceeded.

*Exceeds acute listed species LOC (0.05)

**Exceeds acute non-listed species LOC (0.5)

***Exceeds chronic LOC (1)

RLF = red legged frog

OP = organophosphate

STD = standard
94

Freshwater Invertebrates – Acute Risk

For freshwater invertebrates, the acute risk quotients ranged from 0.002 to 0.057. Two uses 

exceeded the acute listed species LOC (0.05): pineapple (ground and aerial), and paved areas 

(ground and aerial). All other quizalofop-p-ethyl uses were below the LOC of 0.05 (Table 

20).

Freshwater Invertebrates – Chronic Risk

For freshwater invertebrates, the chronic risk quotients were all < 0.001. None of them 

exceeded the chronic LOC (1) for any registered use of quizalofop-p-ethyl (Table 20).

Estuarine/Marine Invertebrates – Acute Risk

For estuarine/marine invertebrates, the acute risk quotients ranged from 0.004 to 0.133. Two 

uses exceeded the acute listed species LOC (0.05): pineapple (ground and aerial), and paved 

areas (ground and aerial). All other quizalofop-p-ethyl uses were below the LOC of 0.05 

(Table 20).

Estuarine/Marine Invertebrates – Chronic Risk

For estuarine/marine invertebrates, the chronic risk quotients ranged from 0.002 to 0.057. 

None of them exceeded the chronic LOC (1) for any registered use of quizalofop-p-ethyl 

(Table 20).

Table 20. Acute and chronic risks from quizalofop-p-ethyl to freshwater and 

estuarine/marine invertebrates

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production

2 apps @ 0.0834 lb ai/A (7-day interval)

Alfalfa

(MN alfalfa OP)

A

G

0.009

0.007

<0.001

<0.001

0.022

0.016

0.009

0.007

Carrot

(CA Row Crop RLF)

A

G

0.008

0.007

<0.001

<0.001

0.019

0.016

0.008

0.007
95

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Chinese cabbage

(CA Cole Crop RLF)

A

G

0.019

0.017

<0.001

<0.001

0.043

0.040

0.019

0.017

Garlic

(CA Garlic RLF)

A

G

0.009

0.007

<0.001

<0.001

0.021

0.017

0.009

0.007

Onion and Radish

(CA onion W/irrig

STD)

A

G

0.005

0.003

<0.001

<0.001

0.012

0.008

0.005

0.003

Red beets

(CA Row Crop RLF)

A

G

0.008

0.007

<0.001

<0.001

0.019

0.016

0.008

0.007

Spinach

(CA lettuce STD)

A

G

0.014

0.012

<0.001

<0.001

0.032

0.028

0.014

0.012

Swiss chard

(CA lettuce STD)

A

G

0.014

0.012

<0.001

<0.001

0.032

0.030

0.014

0.012

All states, food item

2 apps @ 0.0834 lb ai/A (7-day interval)

Sugar beets

(CA sugar beet W/irrig

OP)

A

G

0.005

0.003

<0.001

<0.001

0.012

0.007

0.005

0.003

Sugar beets

(MN sugar beet STD)

A

G

0.014

0.012

<0.001

<0.001

0.033

0.028

0.014

0.012

Except New York

1 app at 0.0695 lb ai/A

Barley and Wheat

(CA Wheat RLF)

A

G

0.006

0.005

<0.001

<0.001

0.014

0.012

0.006

0.005

Barley and Wheat

(ND wheat STD)

A

G

0.006

0.005

<0.001

<0.001

0.014

0.012

0.006

0.005

Barley and Wheat

(OR wheat OP)

A

G

0.004

0.004

<0.001

<0.001

0.009

0.007

0.004

0.003

Barley and Wheat

(TX wheat OP)

A

G

0.006

0.005

<0.001

<0.001

0.014

0.013

0.006

0.005

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)
96

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Canola/rape

(ND canola STD)

A

G

0.007

0.005

<0.001

<0.001

0.017

0.013

0.007

0.006

Crambe

(CA Row Crop RLF)

A

G

0.007

0.005

<0.001

<0.001

0.016

0.012

0.007

0.005

Crambe

(MI beans STD)

A

G

0.011

0.010

<0.001

<0.001

0.026

0.022

0.011

0.010

Soybeans

(MS soybean STD)

A

G

0.020

0.019

<0.001

<0.001

0.046

0.043

0.019

0.018

Sunflowers

(CA corn OP)

A

G

0.006

0.005

<0.001

<0.001

0.014

0.011

0.006

0.005

Sunflowers

(IL Corn STD)

A

G

0.011

0.010

<0.001

<0.001

0.027

0.024

0.011

0.010

Sunflowers

(IN Corn Std)

A

G

0.009

0.008

<0.001

<0.001

0.022

0.019

0.009

0.008

Sunflowers

(KS Corn Std)

A

G

0.017

0.016

<0.001

<0.001

0.039

0.036

0.017

0.016

Sunflowers

(MS corn STD)

A

G

0.016

0.015

<0.001

<0.001

0.037

0.035

0.016

0.015

Sunflowers

(NC corn E STD)

A

G

0.007

0.006

<0.001

<0.001

0.016

0.013

0.007

0.006

Sunflowers

(NC corn W OP)

A

G

0.013

0.012

<0.001

<0.001

0.031

0.028

0.013

0.012

Sunflowers

(ND corn OP)

A

G

0.011

0.009

<0.001

<0.001

0.025

0.021

0.011

0.009

Sunflowers

(OH Corn STD)

A

G

0.012

0.010

<0.001

<0.001

0.027

0.024

0.012

0.010

Sunflowers

(PA corn STD)

A

G

0.010

0.008

<0.001

<0.001

0.022

0.019

0.010

0.008

Sunflowers

(TX corn OP)

A

G

0.014

0.013

<0.001

<0.001

0.032

0.030

0.014

0.013

1 app at 0.0834 lb ai/A
97

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Field Corn

(CA corn OP)

A

G

0.004

0.003

<0.001

<0.001

0.009

0.007

0.004

0.003

Field Corn

(IL Corn STD)

A

G

0.007

0.006

<0.001

<0.001

0.017

0.015

0.007

0.006

Field Corn

(IN Corn Std)

A

G

0.006

0.005

<0.001

<0.001

0.013

0.011

0.006

0.005

Field Corn

(KS Corn Std)

A

G

0.011

0.010

<0.001

<0.001

0.026

0.024

0.011

0.010

Field Corn

(MS corn STD)

A

G

0.010

0.010

<0.001

<0.001

0.024

0.023

0.010

0.010

Field Corn

(NC corn E STD)

A

G

0.005

0.004

<0.001

<0.001

0.012

0.009

0.005

0.004

Field Corn

(NC corn W OP)

A

G

0.009

0.008

<0.001

<0.001

0.020

0.018

0.008

0.007

Field Corn

(ND corn OP)

A

G

0.007

0.006

<0.001

<0.001

0.016

0.013

0.007

0.006

Field Corn

(OH Corn STD)

A

G

0.007

0.006

<0.001

<0.001

0.017

0.014

0.007

0.006

Field Corn

(PA corn STD)

A

G

0.006

0.005

<0.001

<0.001

0.014

0.012

0.006

0.005

Field Corn

(TX corn OP)

A

G

0.028

0.008

<0.001

<0.001

0.020

0.019

0.009

0.008

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Sorghum

(TXsorghumOP)

A

G

0.017

0.016

<0.001

<0.001

0.041

0.038

0.018

0.016

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)

Cotton

(CA cotton W/irrig

STD)

A

G

0.003

0.002

<0.001

<0.001

0.008

0.004

0.003

0.002

Cotton

(MS cotton STD)

A

G

0.014

0.013

<0.001

<0.001

0.034

0.031

0.014

0.013
98

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Cotton

(NC cotton STD)

A

G

0.015

0.014

<0.001

<0.001

0.034

0.032

0.015

0.014

Cotton

(TX cotton OP)

A

G

0.012

0.011

<0.001

<0.001

0.028

0.026

0.012

0.011

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Dry beans

(CA Row Crop RLF)

A

G

0.010

0.008

<0.001

<0.001

0.023

0.019

0.010

0.008

Dry beans

(MI beans STD)

A

G

0.017

0.015

<0.001

<0.001

0.041

0.035

0.018

0.015

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Dry and succulent peas

and lentils (CA Row

Crop RLF)

A

G

0.006

0.005

<0.001

<0.001

0.013

0.011

0.006

0.005

Snap beans

(CA Row Crop RLF)

A

G

0.009

0.007

<0.001

<0.001

0.021

0.017

0.009

0.007

Snap beans

(MI beans STD)

A

G

0.016

0.014

<0.001

<0.001

0.036

0.032

0.016

0.014

Texas, Oklahoma, Kansas, and Colorado, only

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Fallow

(CA Turf RLF)

A

G

0.008

0.006

<0.001

<0.001

0.018

0.013

0.008

0.006

2 apps at 0.0834 lb ai/A (7-days)

Flax

(CA Row Crop RLF)

A

G

0.008

0.007

<0.001

<0.001

0.019

0.016

0.008

0.007

Garbanzos (including 

chick peas) (CA Row 

Crop RLF)

A

G

0.008

0.007

<0.001

<0.001

0.019

0.016

0.008

0.007

Garbanzos (including 

chick peas) (MI beans 

STD)

A

G

0.015

0.013

<0.001

<0.001

0.037

0.030

0.015

0.013
99

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Maine and Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Hybrid 

cottonwood/poplar 

plantations

(PA apple STD V2)

A

G

0.008

0.007

<0.001

<0.001

0.020

0.015

0.009

0.007

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Mint (spearmint and 

peppermint)

(CA lettuce STD)

A

G

0.017

0.014

<0.001

<0.001

0.039

0.035

0.017

0.015

2 apps at 0.111 lb ai/A (7-days)

Non-crop areas 

(uncultivated areas, 

fence rows, roadsides, 

equipment storage 

areas, and other similar 

areas)

(CA right-of-way 

RLF)

A

G

0.020

0.018

<0.001

<0.001

0.046

0.042

0.020

0.018

Non-crop areas

(CA Turf RLF)

A

G

0.009

0.006

<0.001

<0.001

0.020

0.014

0.009

0.006

Non-crop areas

(FL turf STD)

A

G

0.004

0.002

<0.001

<0.001

0.010

0.005

0.004

0.002

Non-crop areas

(PA turf STD)

A

G

0.007

0.004

<0.001

<0.001

0.016

0.008

0.007

0.004

Puerto Rico (pineapple only) and Hawaii, only

2 apps at 0.208 lb ai/A (7-days)

Ornamental and/or 

shade trees (CA

nursery STD)

A

G

0.013

0.007

<0.001

<0.001

0.029

0.017

0.012

0.007
100

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs (μg/L)

Freshwater 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 350 μg 

ai/L

Freshwater 

Invertebrates

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

26600 μg ai/L

Estuarine / 

Marine 

Invertebrates

Acute RQ 

(Peak 

EEC/LC50) 

LC50 = 150 μg 

ai/L

Estuarine / 

Marine 

Invertebrates 

Chronic RQ 

(21-Day EEC/ 

NOAEC) 

NOAEC = 

340 μg ai/L

Pineapple

(MS cotton STD)

A

G

0.055*

0.051*

<0.001

<0.001

0.130*

0.119*

0.055

0.051

1 app at 0.108 lb ai/A

Paved areas (private 

roads/sidewalks)

(CA Impervious RLF)

A

G

0.056*

0.057*

<0.001

<0.001

0.131*

0.133*

0.056

0.057

Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Perennial ryegrass 

grown for seed (ND 

wheat STD)

A

G

0.013

0.011

<0.001

<0.001

0.030

0.026

0.013

0.011

Bold text indicates an LOC was exceeded.

*Exceeds acute listed species LOC (0.05)

**Exceeds acute non-listed species LOC (0.5)

***Exceeds chronic LOC (1)

RLF = red legged frog

OP = organophosphate

STD = standard

Aquatic Vascular and Non-vascular Plants 

Aquatic vascular plant risk quotients ranged from 0.015 to 0.580. Aquatic non-vascular plant 

risk quotients were all < 0.001. None of the aquatic plant risk quotients exceeded the LOC of 

1 for any registered use of quizalofop-p-ethyl (Table 21).

Table 21. Risks from quizalofop-p-ethyl to aquatic vascular and non-vascular plants

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)
101

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Idaho, Montana, Washington, Oregon, and Wyoming, only

Non-food/non-feed seed production

2 apps @ 0.0834 lb ai/A (7-day interval)

Alfalfa

(MN alfalfa OP)

A

G

0.090

0.068

<0.001

<0.001

Carrot

(CA Row Crop RLF)

A

G

0.085

0.069

<0.001

<0.001

Chinese cabbage

(CA Cole Crop RLF)

A

G

0.189

0.173

<0.001

<0.001

Garlic

(CA Garlic RLF)

A

G

0.092

0.073

<0.001

<0.001

Onion and Radish

(CA onion W/irrig

STD)

A

G

0.052

0.034

<0.001

<0.001

Red beets

(CA Row Crop RLF)

A

G

0.085

0.069

<0.001

<0.001

Spinach

(CA lettuce STD)

A

G

0.138

0.120

<0.001

<0.001

Swiss chard

(CA lettuce STD)

A

G

0.138

0.120

<0.001

<0.001

All states, food item

2 apps @ 0.0834 lb ai/A (7-day interval)

Sugar beets

(CA sugar beet W/irrig

OP)

A

G

0.051

0.029

<0.001

<0.001

Sugar beets

(MN sugar beet STD)

A

G

0.143

0.120

<0.001

<0.001

Except New York

1 app at 0.0695 lb ai/A

Barley and Wheat

(CA Wheat RLF)

A

G

0.060

0.052

<0.001

<0.001

Barley and Wheat

(ND wheat STD)

A

G

0.063

0.053

<0.001

<0.001
102

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Barley and Wheat

(OR wheat OP)

A

G

0.041

0.032

<0.001

<0.001

Barley and Wheat

(TX wheat OP)

A

G

0.060

0.055

<0.001

<0.001

1 app at 0.0834 and 1 app at 0.042 lb ai/A (7-days)

Canola/rape

(ND canola STD)

A

G

0.074

0.056

<0.001

<0.001

Crambe

(CA Row Crop RLF)

A

G

0.068

0.054

<0.001

<0.001

Crambe

(MI beans STD)

A

G

0.115

0.099

<0.001

<0.001

Soybeans

(MS soybean STD)

A

G

0.198

0.188

<0.001

<0.001

Sunflowers

(CA corn OP)

A

G

0.059

0.048

<0.001

<0.001

Sunflowers

(IL Corn STD)

A

G

0.116

0.103

<0.001

<0.001

Sunflowers

(IN Corn Std)

A

G

0.094

0.082

<0.001

<0.001

Sunflowers

(KS Corn Std)

A

G

0.169

0.158

<0.001

<0.001

Sunflowers

(MS corn STD)

A

G

0.161

0.151

<0.001

<0.001

Sunflowers

(NC corn E STD)

A

G

0.072

0.057

<0.001

<0.001

Sunflowers

(NC corn W OP)

A

G

0.134

0.121

<0.001

<0.001

Sunflowers

(ND corn OP)

A

G

0.108

0.091

<0.001

<0.001

Sunflowers

(OH Corn STD)

A

G

0.119

0.106

<0.001

<0.001
103

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Sunflowers

(PA corn STD)

A

G

0.099

0.084

<0.001

<0.001

Sunflowers

(TX corn OP)

A

G

0.138

0.129

<0.001

<0.001

1 app at 0.0834 lb ai/A

Field Corn

(CA corn OP)

A

G

0.039

0.032

<0.001

<0.001

Field Corn

(IL Corn STD)

A

G

0.074

0.065

<0.001

<0.001

Field Corn

(IN Corn Std)

A

G

0.058

0.049

<0.001

<0.001

Field Corn

(KS Corn Std)

A

G

0.113

0.106

<0.001

<0.001

Field Corn

(MS corn STD)

A

G

0.104

0.098

<0.001

<0.001

Field Corn

(NC corn E STD)

A

G

0.051

0.041

<0.001

<0.001

Field Corn

(NC corn W OP)

A

G

0.086

0.078

<0.001

<0.001

Field Corn

(ND corn OP)

A

G

0.070

0.059

<0.001

<0.001

Field Corn

(OH Corn STD)

A

G

0.073

0.063

<0.001

<0.001

Field Corn

(PA corn STD)

A

G

0.062

0.053

<0.001

<0.001

Field Corn

(TX corn OP)

A

G

0.087

0.081

<0.001

<0.001

1 app at 0.0834 and 1 app at 0.057 lb ai/A (7-days)

Sorghum

(TXsorghumOP)

A

G

0.177

0.166

<0.001

<0.001

3 apps at 0.034 and 1 app at 0.023 lb ai/A (7-days)
104

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Cotton

(CA cotton W/irrig

STD)

A

G

0.034

0.017

<0.001

<0.001

Cotton

(MS cotton STD)

A

G

0.146

0.135

<0.001

<0.001

Cotton

(NC cotton STD)

A

G

0.150

0.137

<0.001

<0.001

Cotton

(TX cotton OP)

A

G

0.121

0.111

<0.001

<0.001

2 apps at 0.0834 and 1 app at 0.03 lb ai/A (7-days)

Dry beans

(CA Row Crop RLF)

A

G

0.101

0.083

<0.001

<0.001

Dry beans

(MI beans STD)

A

G

0.176

0.154

<0.001

<0.001

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-days)

Dry and succulent peas

and lentils (CA Row

Crop RLF)

A

G

0.056

0.046

<0.001

<0.001

Snap beans

(CA Row Crop RLF)

A

G

0.090

0.074

<0.001

<0.001

Snap beans

(MI beans STD)

A

G

0.159

0.138

<0.001

<0.001

Texas, Oklahoma, Kansas, and Colorado, only

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Fallow

(CA Turf RLF)

A

G

0.080

0.057

<0.001

<0.001

2 apps at 0.0834 lb ai/A (7-days)

Flax

(CA Row Crop RLF)

A

G

0.085

0.069

<0.001

<0.001
105

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Garbanzos (including 

chick peas) (CA Row 

Crop RLF)

A

G

0.085

0.069

<0.001

<0.001

Garbanzos (including 

chick peas) (MI beans 

STD)

A

G

0.015

0.130

<0.001

<0.001

Maine and Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Hybrid 

cottonwood/poplar 

plantations

(PA apple STD V2)

A

G

0.086

0.066

<0.001

<0.001

2 apps at 0.0834 and 1 app at 0.04 lb ai/A (7-days)

Mint (spearmint and 

peppermint)

(CA lettuce STD)

A

G

0.168

0.150

<0.001

<0.001

2 apps at 0.111 lb ai/A (7-days)

Non-crop areas 

(uncultivated areas, 

fence rows, roadsides,

equipment storage 

areas, and other similar 

areas)

(CA right-of-way 

RLF)

A

G

0.202

0.184

<0.001

<0.001

Non-crop areas

(CA Turf RLF)

A

G

0.089

0.062

<0.001

<0.001

Non-crop areas

(FL turf STD)

A

G

0.046

0.020

<0.001

<0.001
106

Use (Scenario) Ariel (A) or 

Ground (G)

1-in-10-year Aquatic EECs 

(μg/L)

Aquatic 

Vascular 

Plants RQ 

(Peak 

EEC/EC50) 

EC50 = 34.5 μg 

ai/L

Aquatic NonVascular Plants

RQ (Peak 

EEC/EC50) 

EC50 = 41000 μg 

ai/L

Non-crop areas

(PA turf STD)

A

G

0.070

0.036

<0.001

<0.001

Puerto Rico (pineapple only) and Hawaii, only

2 apps at 0.208 lb ai/A (7-days)

Ornamental and/or 

shade trees (CA

nursery STD)

A

G

0.127

0.075

<0.001

<0.001

Pineapple

(MS cotton STD)

A

G

0.554

0.516

<0.001

<0.001

1 app at 0.108 lb ai/A

Paved areas (private 

roads/sidewalks)

(CA Impervious RLF)

A

G

0.568

0.580

<0.001

<0.001

Minnesota, only

2 apps at 0.0695 lb ai/A (7-days)

Perennial ryegrass 

grown for seed (ND 

wheat STD)

A

G

0.130

0.111

<0.001

<0.001

***Exceeds the LOC (1)

RLF = red legged frog

OP = organophosphate

STD = standard

Probit Slope Response Analysis of LOC Values and Acute RQ Values

As part of the risk estimation, the probability of mortality associated with the listed acute 

LOC values is estimated along with the probability of acute mortality occurring if exposure 

at the EEC actually occurs. The probability of mortality calculations are based on the probit 

slope dose-response relationship. The probability of mortality for an exposed individual is 

calculated using an Excel spreadsheet tool IECV1.1 (Individual Effect Chance Model 
107

Version 1.1) developed by EFED of the U.S. EPA, OPP, Environmental Fate and Effects 

Division (June 22, 2004).

The model provides the option of inserting taxa-specific probit slopes and confidence 

intervals. If specific information is not available, the model uses a default value of 4.5 for 

the probit slope and 2 and 9 for the upper and lower 95% confidence interval bounds. For 

quizalofop-p-ethyl, taxa-specific data were only available for freshwater invertebrates; 

default values were used for other taxonomic groups. 

Probabilities of mortality were only calculated for scenarios where the risk quotient exceeded 

the acute listed species LOC. For quizalofop-p-ethyl there were only two groups that met 

this criterion – freshwater invertebrates and estuarine/marine invertebrates. All scenarios 

with risk quotients that exceeded the acute LOC were modeled (Table 22).

Table 22. Odds of mortality for an individual freshwater or estuarine/marine 

invertebrate for quizalofop-p-ethyl

RQ Slope 95% Confidence 

Interval

Odds 

(1 in...)

Freshwater invertebrates 

(pineapple - aerial)

0.055 7.82 4.56-11.1 2.93 x 1022

Freshwater invertebrates 

(pineapple - ground)

0.051 7.82 4.56-11.1 3.88 x 1023

Freshwater invertebrates 

(paved areas - aerial)

0.056 7.82 4.56-11.1 1.60 x 1022

Freshwater invertebrates 

(paved areas - ground)

0.057 7.82 4.56-11.1 8.82 x 1021

Estuarine/marine invertebrates 

(pineapple - aerial)

0.130 4.5 2-9 29,900

Estuarine/marine invertebrates 

(pineapple - ground)

0.119 4.5 2-9 62,900

Estuarine/marine invertebrates 

(paved areas)

0.131 4.5 2-9 28,100

Estuarine/marine invertebrates 

(paved areas)

0.133 4.5 2-9 24,800

Risk Description

The following risk description explains the overall direct effect conclusions regarding the 

potential ecological risk from the various uses of quizalofop-p-ethyl. The risk conclusions 

take into consideration all lines of evidence, such as the risk estimates (risk quotient results); 

information on the odds of mortality for the acute risk quotient values; comparisons of non-
108

definitive endpoints (i.e., limit tests) to EECs; information such as monitoring data, field 

studies, and incident data that may provide additional insights into the likelihood of 

exposure; and other factors that modify the likelihood of exposure such as timing of 

application, overlap of area affected and the degree of effect with the presence/absence of 

taxa, species sensitivity distribution, and presence/absence of dietary items.

 DIRECT EFFECTS TO TERRESTRIAL BIRDS, REPTILES, AND AMPHIBIANS

Acute Risk

Acute dose-based and dietary-based risk quotients could not be calculated to evaluate the 

risks to birds because only non-definitive acute toxicity data were available. Instead, the 

non-definitive toxicity values were directly compared to the EECs (Table 23). In all cases, 

none of the dietary EECs were larger than the non-definitive toxicity values for mallard duck, 

the most sensitive. Thus, the potential for risk is considered to be low for acute dose-based 

and dietary-based exposure of birds, reptiles, and land-phase amphibians from quizalofop-pethyl for all registered uses. 

Table 23. Comparison of the highest calculated EEC for each use of quizalofop-p-ethyl 

to the most sensitive avian acute toxicity values

Application Scenario Dietary 

Item EEC (mg ai/kg-bw)

LD50 

(mallard) mg 

ai/kg-bw

EEC 

(mg 

ai/kgdiet)

LC50

(mallard) mg 

ai/kg-diet

Idaho, Montana, Washington, Oregon, and 

Wyoming, only

Non-food/non-feed seed production: alfalfa, 

carrot, Chinese cabbage, garlic, onion, 

radish, red beets, spinach, Swiss chard

All states, food item: sugar beets

2 apps at 0.0834 lb ai/A (7-day interval)

Short 

grass

42.64 >2000 37.44 >5000

Except New York

Barley, wheat

1 app at 0.0695 lb ai/A

Short 

grass 19.00 >2000 16.68 >5000

Canola/rape, crambe, soybeans, sunflowers

1 app at 0.0834 and 1 app at 0.042 lb ai/A 

(7-days)

Short 

grass 31.33 >2000 27.50 >5000

Field corn seed production (herbicidetolerant)

1 app at 0.0834 lb ai/A

Short 

grass 22.80 >2000 20.02 >5000

Sorghum (herbicide-tolerant)

1 app at 0.0834 and 1 app at 0.057 lb ai/A 

(7-days)

Short 

grass 35.43 >2000 31.10 >5000

Cotton

3 apps at 0.034 and 1 app at 0.023 lb ai/A 

(7-days)

Short 

grass 27.55 >2000 24.19 >5000
109

Application Scenario Dietary 

Item EEC (mg ai/kg-bw)

LD50 

(mallard) mg 

ai/kg-bw

EEC 

(mg 

ai/kgdiet)

LC50

(mallard) mg 

ai/kg-diet

Dry beans

2 apps at 0.0834 and 1 app at 0.03 lb ai/A 

(7-days)

Short 

grass 45.32 >2000 39.79 >5000

Dry and succulent peas, lentils, snap beans

1 app at 0.0834 and 1 app at 0.01 lb ai/A (7-

days)

Short 

grass 22.80 >2000 20.02 >5000

Texas, Oklahoma, Kansas, and Colorado, 

only

Fallow

2 apps at 0.0834 and 1 app at 0.04 lb ai/A 

(7-days)

Short 

grass

48.06 >2000 42.19 >5000

Flax, garbanzos (including chick peas)

2 apps at 0.0834 lb ai/A (7-days)

Short 

grass

42.64 >2000 37.44 >5000

Maine and Minnesota, only

Hybrid cottonwood/poplar plantations

1 app at 0.0695 lb ai/A

Short 

grass 35.53 >2000 31.20 >5000

Mint (spearmint and peppermint)

2 apps at 0.0834 and 1 app at 0.04 lb ai/A 

(7-days)

Short 

grass 48.06 >2000 42.19 >5000

Non-crop areas (uncultivated areas, fence 

rows, roadsides, equipment storage areas, 

and other similar areas)

1 app at 0.111 lb ai/A

Short 

grass 30.34 >2000 26.64 >5000

Puerto Rico (pineapple only) and Hawaii, 

only

Ornamental and/or shade trees, pineapple

2 apps at 0.208 lb ai/A (7-days)

Short 

grass 106.35 >2000 93.38 >5000

Paved areas (private roads/sidewalks)

1 app at 0.108 lb ai/A

Short 

grass

29.52 >2000 25.92 >5000

Minnesota, only

Perennial ryegrass grown for seed

2 apps at 0.0695 lb ai/A (7-days)

Short 

grass 35.53 >2000 31.20 >5000

Chronic Risk

Risk quotients were calculated for dietary-based chronic risks. None of the uses exceeded 

the LOC of 1; consequently, effects to listed and non-listed avian, reptile, and terrestrialphase amphibian species are considered unlikely. 

Summary of Risks from Direct Effects

A summary of the potential for acute and chronic risks to birds (surrogates for reptiles and 

land-phase amphibians) is listed below:

The potential for acute risk to non-listed birds (surrogates for reptiles and land-phase 

amphibians) is low, based on comparisons between dose-based and dietary-based 
110

EECs and toxicity data. For all uses, the EECs are much lower than the toxicity 

value. 

The potential for chronic risk to birds (reptiles and land-phase amphibians) is low for 

all quizalofop-p-ethyl uses, based on risk quotients not exceeding the LOC (1). 

 DIRECT EFFECTS TO TERRESTRIAL MAMMALS

Acute Risk

Risk quotients were calculated for dietary and dose-based acute exposures. None of the 

quizalofop-p-ethyl uses exceeded the LOC of 0.1, for listed species. Therefore, effects to 

listed and non-listed mammals are not expected.

Chronic Risk

Risk quotients were calculated for dietary and dose-based chronic exposures. None of the 

quizalofop-p-ethyl uses yielded chronic dietary RQs that exceeded the LOC (1); however, all 

uses had multiple scenarios that exceeded the chronic dose-based LOC of 1. Specifically, all 

uses had risk quotients that exceeded the LOC for small (15 g) and medium-sized (35 g)

mammals consuming diets of short grass. Most uses yielded risk quotients that exceeded the 

LOC for other food items and the large (1000 g) mammal size class (Table 24). The NOAEL 

for mammals is 5 mg ai/kg-bw and the LOAEL is 20 mg ai/kg-bw. For scenarios with risk 

quotients that exceeded the LOC, EECs ranged from 17.08 to 89.03 mg ai/kg-bw. 

Essentially, the EECs are approximately 1 to 4 times the lowest dose tested in which effects 

were observed (3 to 18 times higher than the dose at which no effects were observed). 

Effects included decreases in male and female pup body weight and reduced number of live 

pup births in F1 and F2 generations. Chronic risk quotients for mammals consuming fruits, 

pods, or seeds never exceeded the LOC of 1. 
111

Table 24 Quizalofop-p-ethyl uses that exceeded the chronic dose-based LOC (1) for mammals

Use Dose-based RQs

Short grass Tall grass Broadleaf plants Arthropods

15 g 35 g 1000 g 15 g 35 g 1000 g 15 g 35 g 1000 g 15 g 35 g 1000 g

ID, MT, WA, OR, WY, only:

Non-food/non-feed seed production: alfalfa, carrot, 

Chinese cabbage, garlic, onion, radish, red beets, 

spinach, Swiss chard

TX, OK, KS, CO, only: fallow

All states, food item: sugar beets, dry beans, flax, 

garbanzos (including chick peas), mint (spearmint and 

peppermint)

Yes Yes Yes Yes Yes No Yes Yes No Yes Yes No

Except New York: barley, wheat

All states: field corn seed production (herbicidetolerant), dry and succulent peas, lentils, snap beans

Yes Yes No No No No No No No No No No

Canola/rape, crambe, soybeans, sunflowers, paved 

areas (private roads/sidewalks) Yes Yes Yes Yes No No Yes Yes No No No No

Non-crop areas (uncultivated areas, fence rows, 

roadsides, equipment storage areas, and other similar 

areas)

Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes No

ME, MN, only: hybrid cottonwood/poplar plantations 

MN, only: perennial ryegrass grown for seed 

All states: sorghum (herbicide-tolerant)

Yes Yes Yes Yes Yes No Yes Yes No Yes No No

Cotton Yes Yes No No No No Yes Yes No No No No

Puerto Rico, only: pineapple

HI, only: pineapple, ornamental and/or shade trees Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
112

Summary of Risks from Direct Effects

A summary of the potential for acute and chronic risks to mammals is listed below:

The potential for acute risk to mammals is low for all quizalofop-p-ethyl uses, based 

on risk quotients not exceeding the listed species LOC (0.1). 

There is the potential for chronic risk to listed and non-listed mammals for all 

quizalofop-p-ethyl uses based on the dose-based risk quotients exceeding the LOC 

(1).

DIRECT EFFECTS TO TERRESTRIAL INVERTEBRATES

There is no defined LOC for non-listed terrestrial insects; the interim listed terrestrial 

invertebrate LOC is 0.05. Currently, there is no established threshold for risk to terrestrial 

invertebrates. As such, the level of direct effects to terrestrial invertebrates necessary to 

indirectly affect other taxa that rely on terrestrial invertebrates as a food source or for 

pollination has not been established on a national level, and the use of the interim LOC of 

0.05 will apply to all terrestrial invertebrates without the demarcation of non-listed and listed.

The acute contact toxicity value for the honeybee study with quizalofop-p-ethyl was nondefinitive (LD50 > 50 μg ai/bee); therefore, risk quotients were not calculated. The toxicity 

value was converted to mg/kg-bee, based on the weight of one bee (0.128 g). The 

extrapolated acute contact LD50 values for terrestrial invertebrates was calculated as > 391 

mg ai/kg-diet6and compared to the arthropod predicted EEC. The highest EEC (36.57 mg 

ai/kg-diet) was derived from the pineapple and ornamental and/or shade trees application 

scenario (two applications at 0.208 lb ai/A, 7-days apart). This value was much lower than 

the extrapolated acute contact LD50 (391 mg ai/kg-diet) that was calculated for the honeybee. 

Given that the other quizalofop-p-ethyl application rates are lower, it is unlikely that the 

registered uses will adversely affect terrestrial insects

Summary of Risks from Direct Effects

A summary of the potential for acute risks terrestrial invertebrates is listed below:

The potential for acute risk to terrestrial invertebrates is not expected, based on 

honeybee acute contact LD50 data.

 

6 391 ppm

g

g

0.128

50 50 50 sec

honey bee

honey bee

terrestria l in t

BW

LD

Extrapolat ed LD
113

 DIRECT EFFECTS TO TERRESTRIAL PLANTS

Risk quotients were calculated for listed dicots and listed and non-listed monocots. For 

dicots, risk quotients did not exceed the LOC (1) for listed species. The most sensitive EC25

for dicots was non-definitive; consequently, risk quotients could not be calculated for nonlisted dicot species. However; given that a NOAEC was available for the dicot listed species 

calculations and that the risk quotients from these scenarios did not exceed the LOC, nonlisted dicots are also not expected to be at risk from any of the registered quizalofop-p-ethyl 

uses.

All ground and aerial spray drift scenarios exceeded the LOC (1) for listed and non-listed 

monocots. Application rates of 0.0695 lb ai/A and higher yielded risk quotients that

exceeded the LOCs in additional scenarios (Table 25). Further, there was one major incident 

reported in the EIIS database for quizalofop-p-ethyl. The incident (# I016677-001) occurred 

when spray drift from an application of Assure II (quizalofop-p-ethyl) and Flexstar (sodium 

fomesafen) to soybeans came into contact with a garden in the vicinity of the soybean field. 

Hundreds of herbaceous plants in a home herb garden (20 ft away) and various vegetables in 

another garden (150 ft away) were reported to have been damaged (leaf burn and spotting). 

The incident occurred on 8/2/05 in Missouri and is classified as “possible” to have been 

caused by quizalofop-p-ethyl; however there is some uncertainty given that sodium 

fomesafen was also applied. There was one minor incident listed in the Aggregate Summary 

Module of OPP’s Incident Database for quizalofop-p-ethyl. The formulation, Assure II, was 

associated with minor plant damage between 7/1/01 and 9/30/01. No further information was 

available. 
114

Table 25. Quizalofop-p-ethyl application scenarios that exceeded the LOC for listed and non-listed monocots

Use Non-listed monocot Listed monocot

Dry Semi-aquatic Spray drift Dry Semi-aquatic Spray drift

Ground Aerial Ground Aerial Ground Aerial Ground Aerial Ground Aerial Ground Aerial

ID, MT, WA, OR, WY, only:

Non-food/non-feed seed 

production: alfalfa, carrot, 

Chinese cabbage, garlic, onion, 

radish, red beets, spinach, Swiss 

chard

TX, OK, KS, CO, only: fallow

All states: canola/rape, crambe, 

soybeans, sunflowers, field corn 

seed production (herbicidetolerant), sorghum (herbicidetolerant), dry beans, dry and 

succulent peas, lentils, snap 

beans, flax, garbanzos 

(including chick peas), mint 

(spearmint and peppermint), 

sugar beet)

No No No No No Yes No No No Yes Yes Yes

ME, MN, only: hybrid 

cottonwood/poplar plantations

MN only: perennial ryegrass 

grown for seed

Except NY: barley, wheat

No No No No No Yes No No No Yes No Yes

Cotton No No No No No Yes No No No No No Yes

Non-crop areas, paved areas No No No No No Yes No No Yes Yes Yes Yes

Puerto Rico only: pineapple

HI only: pineapple and 

ornamental and/or shade trees

No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes
115

Buffers may offer a potential mitigation strategy to reduce the concentration of quizalofop-pethyl that reaches non-target monocots. Spray drift from ground and aerial applications was 

modeled to estimate the distance that spray applications can drift from the treated area and 

still be present at concentrations that exceed levels of concern. A quantitative analysis of 

spray drift distances was completed using AgDRIFT (v. 2.11) using default inputs for ground 

applications (i.e., high boom, ASAE droplet size distribution = Very Fine to Fine, 90th data 

percentile) and aerial applications (i.e., ASAE Very Fine to Fine). The results indicate that 

buffers could be set to mitigate adverse effects to non-target species from ground 

applications (spray drift only – runoff is not considered); however, buffers for aerial 

application would need to be greater than 1000 ft (Table 26). These results should be 

considered with the caveat that the most conservative application assumptions were used as 

inputs to the model.

Table 26. Buffer distances for terrestrial monocot scenarios with risk quotients that 

exceeded the spray drift LOC

Use Single 

application Rate 

(lb ai/A)

Fraction of 

Applied

Buffer Distance 

(ft)

Ground Aerial

Listed Monocots

ID, MT, WA, OR, WY, only

Non-food/non-feed seed production: alfalfa, carrot, 

Chinese cabbage, garlic, onion, radish, red beets, 

spinach, Swiss chard

TX, OK, KS, CO, only: fallow

All states:

canola/rape, crambe, soybeans, sunflowers, field 

corn seed production (herbicide-tolerant), sorghum 

(herbicide-tolerant), dry beans, dry and succulent 

peas, lentils, snap beans, flax, garbanzos (including 

chick peas) mint (spearmint and peppermint), sugar 

beet

0.0834 0.009 213 >1000

ME, MN, only: hybrid cottonwood/poplar 

plantations

MN only: perennial ryegrass grown for seed

Except New York: barley, wheat

0.0695 0.011 180

>1000

Cotton 0.034 0.023 95 >1000

Non-crop areas 0.111 0.007 262 >1000

Puerto Rico: pineapple

HI, only: pineapple and ornamental and/or shade 

0.208 0.004 394

>1000
116

trees

Paved areas 0.108 0.007 262 >1000

Non-Listed Monocots

ID, MT, WA, OR, WY, only

Non-food/non-feed seed production: alfalfa, carrot, 

Chinese cabbage, garlic, onion, radish, red beets, 

spinach, Swiss chard

TX, OK, KS, CO, only: fallow

All states:

canola/rape, crambe, soybeans, sunflowers, field 

corn seed production (herbicide-tolerant), sorghum 

(herbicide-tolerant), dry beans, dry and succulent 

peas, lentils, snap beans, flax, garbanzos (including 

chick peas) mint (spearmint and peppermint), sugar 

beet

0.0834 0.018 118 >1000

ME, MN, only: hybrid cottonwood/poplar 

plantations

MN only: perennial ryegrass grown for seed

Except New York: barley, wheat

0.0695 0.021 102

>1000

Cotton 0.034 0.043 52 >1000

Non-crop areas 0.111 0.013 157 >1000

Puerto Rico: pineapple

HI, only: pineapple and ornamental and/or shade 

trees

0.208 0.007 262

>1000

Paved areas 0.108 0.014 148 >1000

Summary of Risks from Direct Effects

A summary of the potential for risks terrestrial plants is listed below:

The potential for direct effects to listed and non-listed terrestrial dicot plants from all 

registered uses of quizalofop-p-ethyl is not expected, based on the risk quotients not 

exceeding the LOC (1).

The potential for direct effects to listed and non-listed terrestrial monocots plants is 

expected to occur for all registered uses of quizalofop-p-ethyl, based on the risk 

quotients exceeding the LOC (1) and plant incident data. 
117

DIRECT EFFECTS TO AQUATIC FISH, INVERTEBRATES, AND PLANTS

Freshwater Fish and Amphibians (Aquatic-Phase), and Estuarine-Marine Fish

Acute Risk

Acute risk quotients for freshwater fish did not exceed the LOCs for listed (0.05) or nonlisted (0.5) species. No incidents with freshwater fish or aquatic-phase amphibians were 

reported, thus adverse effects to freshwater fish on an acute exposure basis are not expected

for registered quizalofop-p-ethyl uses.

Acute data were not available for estuarine/marine fish; however the freshwater fish acute 

data were determined to be sufficiently protective to use as a surrogate (see Effects 

Characterization Section). As with the freshwater fish, risk quotients for estuarine/marine 

fish did not exceed the LOCs for listed (0.05) or non-listed (0.5) species. No incidents with 

estuarine/marine fish were reported, thus adverse effects to estuarine/marine fish on an acute 

exposure basis are not expected from the registered uses of quizalofop-p-ethyl.

Chronic Risk

Chronic freshwater fish data were available and used to represent aquatic-phase amphibians 

in addition to fish. Specifically, data from the fathead minnow were used, although the 

rainbow trout presented a more sensitive acute toxicity value. When the acute-to-chronic 

ratio method was used to estimate a NOAEC for the rainbow trout, it was less conservative 

than the NOAEC in the existing fathead minnow study. Two uses exceeded the chronic LOC 

(1): pineapple (ground and aerial), and paved areas (ground and aerial). 

The pineapple use is geographically restricted to Hawaii and Puerto Rico. The NOAEC and 

LOAEC for freshwater fish was 10 and 30 μg ai/L, respectively. Risk quotients that 

exceeded the LOC had EECs ranging from 17.8 to 19.1 μg ai/L – about half the value of the 

LOAEC and double the value of the NOAEC. Effects for freshwater fish included decreased 

length and weight, and larval mortality.

The paved area use is nation-wide; however, the model was run with the conservative 

assumption that 100% of the quizalofop-p-ethyl applied to an acre was available for off-site 

transport. In reality, this number is probably much lower. Quizalofop is being used as a spot 

treatment for weeds that are present in cracks within a paved area. It is unlikely that it would 

be applied over an entire acre of paved area. EECs for risk quotients that exceeded the LOC 

(100% paved area treated) ranged from 19.6 to 20.0 μg ai/L – about half the value of the 

LOAEC and double the value of the NOAEC (see above paragraph on pineapple use). Table 

27 compares the risk quotients for ground and aerial paved area scenarios with less 

conservative assumptions. Using an assumption that 50% of an acre is treated with 

quizalofop (still a very conservative assumption), the EECs fall below the LOC, indicating 

risk to listed and non-listed species is unlikely from the paved area use. 
118

All other quizalofop-p-ethyl uses were below the LOC of 1 and do not present a chronic 

concern for freshwater fish.

Chronic estuarine/marine fish data were available for risk analysis. Risk quotients did not 

exceed the LOC of 1 and no incidents have been reported. Therefore, adverse effects to 

estuarine/marine fish on a chronic basis are not expected from the registered uses of 

quizalofop-p-ethyl.

Table 27. Risk quotients for alternative quizalofop-p-ethyl offsite transport availability 

for the paved area scenario [bolded values exceed the LOC (acute = 0.05; chronic = 1)]

Scenario 100% 75% 50% 25%

EEC RQ EEC RQ EEC RQ EEC RQ

Aerial (freshwater fish – chronic) 18.33 1.83 13.74 1.37 9.17 0.917 4.58 0.458

Ground (freshwater fish- chronic) 18.62 1.86 13.97 1.40 9.31 0.931 4.66 0.458

Aerial (freshwater invert – acute) 19.65 0.056 14.73 0.042 9.83 0.028 4.91 0.014

Ground (freshwater invert – acute) 19.96 0.057 14.97 0.043 9.98 0.029 4.99 0.014

Aerial (estuarine/ marine invert – acute) 19.65 0.131 14.73 0.098 9.83 0.066 4.91 0.033

Ground (estuarine/ marine invert – acute) 19.96 0.133 14.97 0.100 9.98 0.067 4.99 0.033

Freshwater and Estuarine-Marine Invertebrates

Acute Risk

Acute quizalofop-p-ethyl toxicity data for freshwater invertebrates were available. Two uses 

exceeded the acute listed species LOC (0.05), but none exceeded the acute non-listed species 

LOC (0.5). The first use, pineapple, is geographically restricted to Hawaii and Puerto Rico. 

The other use, paved areas, is nation-wide. The paved area scenario was modeled using the 

conservative assumption that 100 percent of the applied material is available for off-site 

transport. In reality, it is probably a much lower percentage. Quizalofop is being used as a 

spot treatment for weeds that are present in cracks within a paved area. It is unlikely that it 

would be applied over an entire acre of paved area. Table 27 presents the EECs and risk 

quotients that would be derived from less conservative scenarios. Given that a 75% offsite 

transport assumption (still very conservative) results in risk quotients below the LOC, it is 

unlikely that quizalofop-p-ethyl applications to paved areas would result in adverse acute 

risks to freshwater invertebrates. There was a 1 in 2.93 x 1022 chance of an individual being 

affected by the pineapple use and a 1 in 8.82 x 1021 chance of an individual being affected by 

the paved area use. All other quizalofop-p-ethyl uses presented risk quotients below the 

LOC of 0.05, indicating these uses are not expected to affect freshwater invertebrates on an 

acute basis.

Acute quizalofop-p-ethyl toxicity data for estuarine/marine invertebrates were available. 

Two uses exceeded the acute listed species LOC (0.05), but none exceeded the acute non-
119

listed species LOC (0.5). The first use, pineapple, is geographically restricted to Hawaii and 

Puerto Rico. The other use, paved areas, is nation-wide. The paved area scenario was 

modeled using the conservative assumption that 100 percent of the applied material is 

available for off-site transport. In reality, it is probably a much lower percentage. 

Quizalofop is being used as a spot treatment for weeds that are present in cracks within a 

paved area. It is unlikely that it would be applied over an entire acre of paved area. Table 27 

presents the EECs and risk quotients that would be derived from less conservative scenarios. 

Given that a 25% offsite transport assumption (reasonably conservative assumption) results 

in risk quotients below the LOC, it is unlikely that quizalofop-p-ethyl applications to paved 

areas would result in adverse acute risks to estuarine/marine invertebrates. There is a 1 in 

29,900 chance of an individual being affected by the pineapple use and a 1 in 24,800 chance 

of an individual being affected by the paved area use. All other quizalofop-p-ethyl uses 

presented risk quotients below the LOC of 0.05, indicating these uses are not expected to 

affect estuarine/marine invertebrates on an acute basis.

Acute toxicity data were available for estuarine/marine mollusks (Eastern oyster). The data 

were based on shell growth and were not the most sensitive endpoint (EC50 = 0.19 mg ai/L), 

thus risk quotients were not calculated. However, to refine the risk assessment, the oyster 

endpoint was considered to determine if mollusks could be removed from the pool of species 

potential at-risk from registered quizalofop uses. In particular, pineapple is the only use 

where risk quotients exceeded the LOC for acute exposures to freshwater and 

estuarine/marine invertebrates. The difference between the most sensitive EC50 (mysid 

shrimp = 0.15 mg ai/L) and the oyster EC50 is small and still results in risk quotients above 

the LOC for the pineapple use. The value is used as a surrogate for freshwater mollusks 

because data are not otherwise available. Consequently, freshwater and estuarine/marine 

mollusks may be adversely affected by the pineapple use on an acute basis.

As with plants, AgDrift (ver. 2.11) was used to determine a buffer distance at which 

quizalofop-p-ethyl residues from spray drift would be below the acute listed species LOC 

(0.05). The default inputs for ground applications (i.e., high boom, ASAE droplet size 

distribution = Very Fine to Fine, 90th data percentile) and aerial applications (i.e., ASAE 

Very Fine to Fine) were used. The results (0 ft buffers) indicated that spray drift is not the 

driving force for the scenarios that produced risk quotients that exceeded the LOC (Table 

28).

 

Table 28. Buffer distances for freshwater and estuarine/marine invertebrate scenarios 

with risk quotients that exceeded the LOC

Use Single 

application Rate 

(lb ai/A)

Initial Average Concentration (ng ai/L) at 

acute listed LOC (0.05). FW = 17500; E/M = 

7500
120

Freshwater Invert. 

Buffer (ft)

Estuarine/ Marine 

Invert. Buffer (ft)

Paved areas (ground) 0.108 0 0

Paved areas (aerial) 0.108 0 0

Pineapple (ground) 0.208 0 0

Pineapple (aerial) 0.208 0 0

Chronic Risk

Quizalofop-p-ethyl chronic toxicity data for freshwater invertebrates were available. Risk 

quotients were all quite low (< 0.001) and did not exceed the LOC of 1 for any registered 

quizalofop-p-ethyl uses.

Quizalofop-p-ethyl chronic toxicity data for estuarine/marine invertebrates were not 

available; thus, the acute-to-chronic ratio method was used to estimate a NOAEC. The risk 

quotients did not exceed the LOC (1) for any of the registered quizalofop-p-ethyl uses.

Aquatic Plants – Vascular and Non-vascular

Data were available for aquatic vascular and non-vascular plants. Risk quotients for both 

groups were below the LOC of 1. Thus adverse effects to listed species from registered 

quizalofop-p-ethyl uses are not expected to occur. 

Summary of Risk from Direct Effects

A summary of the potential for risks to aquatic organisms is listed below:

Risk is unlikely for acute exposures to freshwater fish, aquatic-phase amphibians, and 

estuarine/marine fish.

Risk is unlikely for chronic exposures to freshwater invertebrates, estuarine/marine 

invertebrates, and estuarine/marine fish.

There is the potential for acute risks for freshwater invertebrates for the pineapple 

(Hawaii and Puerto Rico) and the paved areas (nation-wide) uses.

There is the potential for acute risks for estuarine/marine invertebrates for the 

pineapple (Hawaii and Puerto Rico) and paved areas (nation-wide) uses.

There is the potential for chronic risks for freshwater fish for the pineapple (Hawaii 

and Puerto Rico) and paved areas (nation-wide) uses.

 

Listed Species Effects Analysis

The direct and indirect effects analysis for general taxa of listed species is summarized in 

Table 29, for quizalofop-p-ethyl uses. The analysis is based on the direct and indirect effects 

concluded from the analysis of risk estimates. 
121

Table 29. Summary of indirect and direct effects to listed species and preliminary effects determination for quizalofop-p-ethyl 

uses 

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Non-vascular 

Aquatic Plant 

Species

Primary productivity No Effect – risk 

quotients below 

LOC. 

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat near aquatic 

environments. It could affect non-vascular plant habitat by changing the 

water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, 

indirect effects to aquatic non-vascular plants from effects to terrestrial plants 

may occur.

However, currently, there are no listed non-vascular aquatic plant species, 

therefore adverse effects to listed non-vascular plants are not expected. 

No Effect

Vascular 

Aquatic Plant 

Species

Primary productivity 

assessed from effects on 

main stem length, total 

stem length (main + 

laterals), and fresh 

weight

No Effect – risk 

quotients below 

LOC. 

Direct effects to non-listed and listed monocots terrestrial may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat near aquatic 

environments. It could affect vascular plant habitat by changing the water 

temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect 

effects to aquatic vascular plants from effects to terrestrial plants may occur.

May affect and likely affected based on indirect effects from direct effects on 

terrestrial monocots.

May Affect, Likely to 

Adversely Affect 

Freshwater 

Fish and 

Amphibians

Acute mortality No Effect – risk 

quotients below 

LOC.

Adverse direct effects may be expected to aquatic organisms [fish (chronic), 

invertebrates (acute), terrestrial monocots] as potential food sources. 

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat near aquatic 

environments. It could affect freshwater fish and amphibian habitat by 

May Affect, Likely to 

Adversely Affect 
122

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Chronic survival, growth 

and reproduction 

May Affect, Likely 

to Adversely Effectrisk quotients above 

LOC. 

changing the water temperature, dissolved oxygen levels, sedimentation, etc. 

Therefore, indirect effects to freshwater fish and amphibians from effects to 

terrestrial monocots may occur.

Indirect effects to aquatic habitats from terrestrial monocots could indirectly 

affect aquatic organism availability as a food source for other organisms. 

This could adversely affect freshwater fish and amphibians by altering prey 

populations. 

The may affect, likely to adversely affect determination is based on direct 

chronic effects to freshwater fish and amphibians as well as indirect effects 

from direct effects on aquatic organisms (fish, invertebrates, terrestrial 

monocots), if the species is dependent on them as a food source, and from 

adverse effects on terrestrial monocots which may affect habitat and/or 

aquatic prey populations

Freshwater 

Invertebrates

Acute mortality May Affect, Likely 

to Adversely Affect –

risk quotients above 

LOC.

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. It could result in reduced growth of 

non-target plants and modify the structural habitat near aquatic environments. 

This could affect freshwater invertebrate habitat by changing the water 

temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect 

effects to freshwater invertebrates from effects to terrestrial monocots may 

occur.

Indirect effects to aquatic habitats from terrestrial monocots could indirectly 

affect aquatic organism availability as a food source for other organisms. 

This could adversely affect freshwater invertebrates affected by changing 

prey populations. 

The may affect and likely to adversely affect determination is based on direct 

acute effects to freshwater invertebrates and indirect effects from direct 

effects on terrestrial monocots, which may affect habitat and and/or aquatic 

prey populations.

May Affect, Likely to 

Adversely Affect 

Chronic survival and 

reproduction 

No Effect – risk 

quotients below 

LOC. 
123

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Estuarine/ 

Marine Fish

Acute mortality No Effect – risk 

quotients below LOC 

(based on surrogate 

data). 

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat near aquatic 

environments. It could affect estuarine/marine fish habitat by changing the 

water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, 

indirect effects to estuarine/marine fish from effects to terrestrial monocots 

may occur.

Indirect effects to aquatic habitats from terrestrial monocots could indirectly 

affect aquatic organism availability as a food source for other organisms. 

This could adversely affect estuarine/marine fish by altering prey 

populations. 

Direct effects to estuarine/marine invertebrates on an acute basis could 

decrease the food supply for estuarine/marine fish.

The may affect and likely to adversely affect determination is based on 

indirect effects from direct effects to terrestrial monocots and aquatic 

organisms, which may affect habitat and and/or aquatic prey populations.

May Affect, Likely to 

Adversely Affect

Assessment of chronic 

growth and survival

No Effect – risk 

quotients below 

LOC. 

Estuarine/ 

Marine 

Invertebrates

Acute mortality May Affect, Likely 

to Adversely Affectrisk quotients above 

LOC

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat near aquatic 

environments. It could affect estuarine/marine invertebrate habitat by 

May Affect, Likely to 

Adversely Affect
124

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Assessment of chronic 

growth and reproductive 

effects

May Affect, Likely 

to Adversely Affect –

risk quotients above 

LOC (based on 

acute-to-chronic 

ratio).

changing the water temperature, dissolved oxygen levels, sedimentation, etc. 

Therefore, indirect effects to estuarine/marine invertebrates from effects to 

terrestrial monocots may occur.

Indirect effects to aquatic habitats from terrestrial plants could indirectly 

affect aquatic organism availability as a food source for other organisms. 

Thus, estuarine/marine invertebrates may be adversely affected by changes in 

prey populations. 

The may affect and likely to adversely affect determination is based on direct 

acute and chronic risks to estuarine/marine invertebrates and indirect effects 

from direct effects on terrestrial monocots, which may affect habitats and/or 

aquatic prey populations

Non-target 

plants in 

terrestrial and 

semi-aquatic 

areas

Primary productivity 

assessed from effects on 

biomass as measured 

using survival and dry 

weight; incident data.

May Affect and 

Likely to Adversely 

Affect –

Risk quotients above 

LOC for monocots

Direct chronic effects to mammals may adversely affect plants because some 

mammals act as seed dispersers and pollinators. A reduction in these 

services could affect plant reproduction and establishment. 

The may affect and likely to adversely affect determination is based on direct 

risks to terrestrial monocots and indirect effects from direct effects to 

mammals (chronic), which may act as pollinators and seed dispersers.

May Affect, Likely to 

Adversely Affect

Birds, 

Reptiles, and 

Land-Phase 

Acute mortality No Effect – EECs 

below LOC.

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat. Resources for nests, 

May Affect, Likely to 

Adversely Affect
125

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Amphibians Chronic reproduction No Effect – risk 

quotients below 

LOC. 

food, or camouflage may be diminished. Therefore, indirect effects to birds, 

reptiles, and land-phase amphibians from effects to terrestrial monocots may 

occur.

Direct chronic effects to mammals may reduce prey availability for birds, 

reptiles, and land-phase amphibians. These mammals may also provide 

habitat by modifying the environment (e.g., building a burrow that is later 

used by a reptile). 

Aquatic food sources may also be affected because of direct effects to aquatic 

invertebrates (acute), and freshwater fish (chronic). This may decrease food 

availability for those birds, reptiles, and land-phase amphibians that rely on 

aquatic organisms.

The may affect and likely adversely affect determination is based on indirect 

effects from direct effects to terrestrial monocots, mammals (chronic), 

aquatic invertebrates (acute), and freshwater fish (chronic). 

Mammals Acute mortality No Effect – risk 

quotients below 

LOC. 

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift or runoff. This could result in reduced growth 

of non-target plants and modify the structural habitat. Resources for nests, 

food, or camouflage may be diminished. Therefore, indirect effects to 

mammals from effects to terrestrial monocots may occur.

Aquatic food sources may also be affected because of direct effects to aquatic 

invertebrates (acute), and freshwater fish (chronic). This may decrease food 

availability for those mammals that rely on aquatic organisms.

The may affect and likely to adversely affect determination is based on 

indirect effects from direct effects to terrestrial monocots, aquatic 

invertebrates (acute), and freshwater fish (chronic).

May Affect, Likely to 

Adversely Affect 

Chronic Reproduction May Affect, Likely 

to Adversely Affect –

risk quotients above 

LOC.
126

Listed species 

group

Direct Effect 

Assessment Endpoints

Direct Effects Indirect

Effects

Effects Determination

Terrestrial 

Insects

Acute mortality based on 

contact

No Effect – EECs 

below LOC.

Direct effects to non-listed and listed terrestrial monocots may occur from 

quizalofop-p-ethyl spray drift and runoff exposure; therefore, indirect effects 

could occur from an alteration in habitat in which a species relies on for 

forage, shelter, and/or reproduction needs.

The may affect and likely to adversely affect determination is based on 

indirect effects from direct effects to terrestrial monocots.

May Affect, Likely to 

Adversely Affect
127

ACTION AREA

In the case of a nation-wide risk assessment conducted under registration review, the action 

area will encompass the entire U.S. and its territories. The purpose of defining the action 

area as the entire U.S. and its territories is to ensure that the initial area of consideration 

encompasses all areas where the pesticide may be used now and in the future, including the 

potential for off-site transport via spray drift and downstream dilution. Additionally, the 

concept of a nation-wide action area takes into account the potential for direct and indirect 

effects and any potential modification to critical habitat based on ecological effect measures 

associated with reduction in survival, growth, and reproduction, as well as the full suite of 

sub-lethal effects available in the effects literature. 

It is important to note that the nationwide action area does not imply that direct and/or 

indirect effects and critical habitat modification are expected to or are likely to occur over the 

full extent of the action area, but rather to identify all listed species and critical habitat that 

may potentially be affected by the action. The Agency will use more rigorous analysis 

including consideration of available land cover data, toxicity data, and exposure information 

to determine areas where individual listed species and designated critical habitat may be 

affected or modified via endpoints associated with reduced survival, growth, or reproduction.

 

 EFFECTS AREA DETERMINATION

The potential for direct and/or indirect effects is possible to listed species from exposure to 

quizalofop-p-ethyl. 

Direct Effects

There are potential direct effects to listed species for the following taxa:

Mammals (based on chronic risk quotients exceeding the LOC)

Terrestrial Monocots (based on risk quotients exceeding the LOC)

Freshwater Fish (based on chronic risk quotients exceeding the LOC)

Freshwater Invertebrates (based on acute risk quotients exceeding the LOC)

Estuarine/Marine Invertebrates (based on acute risk quotients exceeding the LOC)
128

Indirect Effects

As there are potential direct effects to mammals, terrestrial monocots, freshwater fish, 

freshwater invertebrates, and estuarine/marine invertebrates, indirect effects could occur to 

other taxa.

Indirect effects to listed fish, aquatic invertebrates, amphibians, reptiles, and other 

terrestrial organisms (e.g. birds, mammals and other invertebrates) that are dependent 

on aquatic invertebrates and plants for food.

Indirect effects to terrestrial plants for which terrestrial animals (e.g. birds and 

mammals) are needed for reproduction (e.g. pollination, seed dispersal) as there may 

be a potential change in terrestrial animal communities/populations. 

Indirect effects to a listed species that is dependent on a mammal, freshwater fish, or 

aquatic invertebrate.

Indirect effects to listed species that are dependent on a monocot in terrestrial or 

semi-aquatic areas during some phase of their life-cycle for things such as food, 

shelter, and reproductive habitats. 

The following table shows the potential taxa indirectly affected by direct effects (Table 30) 

Table 30. Organism groups that are potentially indirectly affected by direct effects to 

other organisms (specific to quizalofop-p-ethyl uses)

Taxon Directly Affected Taxon Indirectly Affected Reason for Indirect Effect

Mammals Reptiles, Birds, Plants, Amphibians Change in prey population (food 

source); Reduction in potential 

pollinators/seed dispersers

Aquatic Invertebrates Fish, Reptiles, Amphibians, Plants, 

Mammals

Change in prey population (food 

source)

Fish Reptiles, Fish, Amphibians, 

Mammals, Birds

Change in prey population (food 

source)

Terrestrial Monocots All taxa (birds, mammals, reptiles, 

amphibians, fish, aquatic and 

terrestrial invertebrates)

Change in food sources; change in 

habitats

Based on this screening-level assessment, there are potential risks of direct effects to listed 

mammals, monocots, freshwater invertebrates, estuarine/marine invertebrates, and freshwater 

fish and non-listed monocots, mammals, and freshwater fish from the use of quizalofop-pethyl on some of its registered use sites. Listed species of all taxa may also be affected 

through indirect effects because of the potential direct effects on listed and non-listed species. 

Potential direct effects on listed mammals, monocots, freshwater invertebrates, 

estuarine/marine invertebrates, and freshwater fish and non-listed monocots, mammals, and 

freshwater fish from the use of quizalofop-p-ethyl may be associated with modification of 

primary constituent elements of designated critical habitats, where such designations have 

been made. However, at this current stage of the Registration Review process, it is 
129

premature to make effects determinations for listed species until further refinements are 

conducted. To make effects determinations for individual species, useful refinements may 

include analyses of 1) more detailed, species-specific ecological and biological data; 2) more 

detailed and accurate information on quizalofop-p-ethyl use patterns; and 3) sub-county level 

spatial proximity data for the co-occurrence of potential effects areas and listed species and 

any designated critical habitat. Examples of such refinements are described below.

EFED is currently developing tools that are expected to further refine the assessment and are 

designed to support effects determinations for individual federally listed species and their 

designated critical habitats (where applicable). Scientific information obtained from the U.S. 

Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and other 

reliable sources is being collated by EFED to address all currently listed species. The 

information will be stored in an Office of Pesticide Programs Pesticide Registration 

Information SysteM (PRISM) knowledgebase. The listed species knowledgebase will 

consist of an information repository that houses biological and behavioral information 

relevant to individual species (e.g., habitat, diet, and life history, including specific temporal 

and spatial associations) and a document repository that contains supporting documents (e.g., 

USFWS recovery plans) and electronic information (e.g., GIS data files). For terrestrial taxa, 

the biological information relevant to risk quotient (RQ) calculations (e.g., diet and body 

weight) will be used to parameterize exposure estimates to derive species-specific RQs using 

a method consistent with currently used methods in the T-REX and T-HERPS models. 

Refinements may also include more detailed analyses of the registered uses and their use 

patterns that result in LOC exceedances for federally listed species in the screening-level 

assessment. The analyses may include more information on where, when, and how 

quizalofop-p-ethyl is used on all use sites. Actual usage data (when available) and national 

land-cover datasets that indicate potential use sites [e.g., national land cover dataset (NLCD), 

crop data layer (CDL)] may be used to support a more refined analysis of where quizalofopp-ethyl is reasonably expected to be used. Similarly, refinements for the timing of 

applications and how quizalofop-p-ethyl is used may be based on the analysis of additional 

usage data, beyond what were available at the time of the screening-level assessment, and a 

more in-depth exploration of agronomic practices. 

In addition, a committee of the National Research Council (NRC) has been tasked with 

providing advice on ecological risk assessment tools and scientific approaches under ESA 

and FIFRA (Project Identification Number DELS-BEST-11-01). The committee has been 

asked to review the use of “best available data;” methods for evaluating sublethal, indirect, 

and cumulative effects; the state of the science regarding assessment of mixtures and 

pesticide inert ingredients; the development, application, and interpretation of results from 

predictive models; uncertainty factors; and what constitutes authoritative geospatial and 

temporal information for the assessment of individual species and habitat effects. The 

Agency anticipates that this NRC report, tentatively expected in Spring 2013, will provide 

recommendations to ensure the scientific soundness and maximize the utility of risk 

assessment refinements for listed species.
130

The refinements based on individual species data; additional, detailed usage information, 

when available; and further recommendations from the NRC report are expected to help to 

more accurately identify potential areas of effect and to better inform effects and habitat 

determinations for listed species and any designated critical habitats. For example, if 

quizalofop-p-ethyl is used when a particular species of concern is not present (e.g., it is 

migratory) or is not co-located in space, then risk of potential direct effects to the species 

may often be precluded. If LOCs are still exceeded for monocots, mammals, freshwater 

invertebrates, estuarine/marine invertebrates, and freshwater fish after conducting the refined 

analyses, further analyses of the potential spatial and temporal co-occurrence of listed species 

of concern (and any designated critical habitat) may be conducted. The extent of possible 

refinement in the analyses of spatial/temporal co-occurrence will largely depend on the scale 

and quality of the available sub-county level use site (e.g., NLCD, CDL) and species location 

data.

The Agency has made several refinements to the list of endangered and threatened species 

that may be affected by quizalofop-p-ethyl uses. To date, there are 1442 listed species 

identified in the LOCATES database (v. 2.2.4, derived from USFWS and NMFS). For 1295 

of these, a “no effect” determination for direct and indirect effects can be made based on a 

lack of geographical overlap, based on a county level of resolution, between the species and 

quizalofop-p-ethyl uses (Appendix J, Table J-1). A further 26 species can be eliminated from 

consideration of direct effects (i.e., “no effects”) based on species specific ecological and 

biological information from listed species trustee agencies (Appendix J, Table J-2). The 

remaining 121 species will need to be considered in more depth before effects calls are made

(Appendix J, Table J-3). The biological, geographical, and use pattern information outlined 

above will be necessary to refine the assessment.
131

Uncertainties

A description of assumptions, uncertainties, strengths, and limitations of the basic risk 

assessment performed is described in Chapter 6 of the Agency’s Overview Document (EPA, 

2004) and includes those related to exposure for all taxa, those related to exposure for aquatic 

species, those related to exposure for terrestrial animals, those related to the effects 

assessment, and those associated with the acute LOC values. This Chapter discusses 

additional uncertainties associated with refinements made to the basic risk assessment.

Effects and Risk Assessment Uncertainties

Ecotoxicity Data Gaps

There were several ecotoxicity endpoints for which data were not available or available data 

were non-definitive. 

Estuarine/Marine Fish (Acute) OPPTS 850.1075. In the Problem Formulation, data 

were not requested because a registrant study had recently been submitted for this 

endpoint. A detailed review of the study at a later date indicated that it was “invalid” 

and thus not useable for risk assessments. To fill this data gap, freshwater and 

estuarine/marine acute fish toxicity studies for two structurally similar chemicals 

(fenoxaprop-p-ethyl and fenoxaprop-ethyl) were reviewed. The fenoxaprop-ethyl 

data indicated that freshwater fish are more sensitive than estuarine/marine fish. A 

comparison of quizalofop-p-ethyl acute freshwater fish data to fenoxaprop-ethyl 

indicated that quizalofop-p-ethyl is more toxic than fenoxaprop-ethyl. Thus it was 

determined that acute freshwater fish data from quizalofop-p-ethyl would be a 

protective surrogate for the missing estuarine/marine data. 

Estuarine/Marine Invertebrate (Chronic) OPPTS 850.1350. In the Problem 

Formulation, data were not requested because it was possible to calculate an acute-tochronic ratio using freshwater invertebrates (waterflea) as a surrogate. 

Freshwater Fish (Chronic) OPPTS 850.1400. Chronic data are available for the 

fathead minnow; however, the most sensitive acute freshwater fish endpoint is for the 

rainbow trout. Acute toxicity information is not available for the fathead minnow. 

To ensure that the most sensitive chronic endpoint for freshwater fish was employed 

in the risk assessment, the acute to chronic ratio methodology was applied. An acutechronic pair of data was available for the fathead minnow for fenoxaprop-p-ethyl, a 

structurally similar chemical to quizalofop-p-ethyl. The ratio between the 

fenoxaprop-p-ethyl fathead minnow endpoints was applied to the quizalofop-p-ethyl 

acute freshwater fish endpoint to derive a protective freshwater fish chronic endpoint.

Avian (Acute) (LD50) OPPTS 850.2100. Definitive data were not available for either 

the LD50 or NOEL. EECs, based on the highest application rate, were less than one 
132

tenth of the LD50 (>2000 mg ai/kg-bw), indicating that more refined, definitive data 

were not necessary for this assessment.

Passerine Birds (Acute) (LD50) OPPTS 850.2100. Data were not available. At the 

time the Problem Formulation was written, passerine bird data were not required. In 

lieu of this endpoint, the acute oral toxicity of quizalofop-p-ethyl to the mallard duck 

and common quail was used to evaluate risk. 

Avian (Chronic) (NOAEC) OPPTS 850.2300. The mallard duck study presented a 

non-definitive (less than) NOAEC. Given that the NOAEC was a “less than” value it 

presents uncertainty as to the true NOAEC and cannot be used in the risk assessment 

to calculate risk quotients. Mallard duck data from two structurally similar chemicals 

(fenoxaprop-p-ethyl and fenoxaprop-ethyl) were considered as potential surrogates 

for the toxicity data. Fenoxaprop-ethyl yielded a NOAEC (180 mg ai/kg-diet) that 

was below the quizalofop-p-ethyl value (< 296 mg ai/kg-diet). Given the similarity 

between fenoxaprop and quizalofop, it was decided that the fenoxaprop-ethyl mallard 

duck NOAEC could be used in place of the non-definitive quizalofop-p-ethyl value. 

Aquatic Non-Vascular Plants (EC50) OPPTS 850.5400. Three of the four Tier 2 

studies for non-vascular plants were non-definitive (greater than); these were also the 

most sensitive toxicity values. To justify the use of a less sensitive endpoint, nonvascular studies from two structurally similar chemicals (fenoxaprop-p-ethyl and 

fenoxaprop-ethyl) were considered. These chemicals showed a similar trend – nondefinitive toxicity values for the more toxic endpoints and definitive numbers at 

higher values. In addition, the fenoxaprop toxicity values were within the same order 

of magnitude as the quizalofop values. Thus, it was determined that using the 

definitive quizalofop-p-ethyl toxicity value was a reasonable approach, given that the 

lower toxicity values were all “greater than” values.

Application Rates

Several labels did not include the seasonal maximum application rate for quizalofop-p-ethyl. 

In these cases, seasonal maximum application rates were assumed based on other information 

from the label or similar application patterns for uses that did contain the complete 

information. The Biological and Economic Division (BEAD) of OPP was consulted and they 

concurred with the assumptions. The following scenarios were affected:

Non-crop areas (uncultivated areas, fence rows, roadsides, equipment storage areas, 

and other similar areas) – seasonal maximum application rate assumed to be 

equivalent to twice the single maximum application rate

Paved areas (private roads/sidewalks) – seasonal maximum application rate assumed 

to be equivalent to single maximum application rate

Hybrid cottonwood/poplar plantations – seasonal maximum application rate assumed 

to be equivalent to two applications at the single maximum application rate
133

Fate Data Gaps

Little data are available for the degradates of concern. Potentially, degradate fate data could 

be estimated from parent studies. However, the resulting estimates might be highly 

uncertain. The 3-OH-quizalofop acid degradate was only found in more recent studies. 

Potentially, this degradate of concern is unaccounted for in the TTR calculated from older 

fate studies and therefore represents an additional source of uncertainty.

Additionally, the parent fish bioconcentration study was not performed under conditions that 

did not allow the fish to be continuously exposed to the parent compound. The highest BCF 

was seen in viscera in the first few days of the study, presumably when the parent had not yet 

degraded. As the test progressed, the BCFs declined. 

Incomplete Life Histories of Listed Species

Currently, a database of life histories for each of the listed animals and plants is not available 

for use by EFED. These life histories would include information such as body size at each 

life stage, food sources, relationships with other taxa, habitat, and reproductive habits. As 

such, conservative (protective) assumptions were made concerning the potential relationships 

between species in that each species was assumed to have a relationship with the other taxa. 

This is assumed to be an overestimation of the actual species that have a species dependant 

relationship. 

Locations of Listed Species

In addition, the specific occurrences of listed species are not known in some cases beyond the 

county-level. If the location of a species was not known in greater detail than the county 

level, the species was assumed to occur anywhere within that county at any time. Likewise, 

crop location data are also uncertain. Crops may rotate every year and some spatial datasets 

combine several crop types, making it impossible to distinguish one crop from another. 

Further, timing may play a role in the location of species and whether it overlaps with the 

time that a particular crop is in a field. These assumptions may lead to an overestimation of 

co-occurrence with quizalofop-p-ethyl exposure and overestimation of the number of species 

potentially at risk.

Other Routes of Exposure

Screening-level risk assessments for applications of pesticides consider dietary exposure 

alone. Other routes of exposure, not considered in this assessment, are discussed below:

Incidental soil ingestion exposure - This risk assessment does not consider incidental soil 

ingestion. Available data suggest that up to 15% of the diet can consist of incidentally 

ingested soil depending on the species and feeding strategy (Beyer et al., 1994). This route 
134

of exposure may be important for applications of quizalofop-p-ethyl for spray applications, 

especially before crops are planted.

Dermal Exposure - The screening assessment does not consider dermal exposure, except as it 

is indirectly included in calculations of risk quotient’s based on lethal doses per unit of 

pesticide treated area. Dermal exposure may occur through three potential sources: (1) direct 

application of spray to terrestrial wildlife in the treated area or within the drift footprint, (2) 

incidental contact with contaminated vegetation, or (3) contact with contaminated water or 

soil. As foliar applications are primary application routes on the registered labels for 

quizalofop-p-ethyl, dermal contact with quizalofop-p-ethyl to non-target animals may occur.

Foliar Dissipation Half-life

An additional source of uncertainty is the foliar dissipation half-life, which is useful for spray 

applications to foliage. No half-life data were provided, thus a default of 35 days was used. 

It is not known if this half-life over or under-estimates the true half-life for quizalofop-pethyl. 

Species Sensitivity

Although the screening-level risk assessment relies on a selected toxicity endpoint from the 

most sensitive species tested, it does not necessarily mean that the selected toxicity endpoints 

reflect the sensitivity of the most sensitive species existing in a given environment. The 

relative position of the most sensitive species tested in the distribution of all possible species 

is a function of the overall variability among species to a particular chemical. In the case of 

listed species, there is uncertainty regarding the relationship of the listed species’ sensitivity 

and the most sensitive species tested.

The Agency is not limited to a base set of surrogate toxicity information in establishing risk 

assessment conclusions. The Agency also considers toxicity data on non-standard test 

species when available.

Endocrine Disruptor Screening Program (EDSP) 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential 

adverse outcomes from exposure to chemicals. Collectively, these studies include acute, 

subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, 

developmental, reproductive, and general or systemic toxicity. These studies include 

endpoints which may be susceptible to endocrine influence, including effects on endocrine 

target organ histopathology, organ weights, estrus cycling, sexual maturation, fertility, 

pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard 

assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental 

and reproductive effects in different taxonomic groups. As part of its recent registration on 
135

herbicide-tolerant corn and sorghum, EPA reviewed these data and selected the most 

sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. 

However, as required by FFDCA section 408(p), quizalofop-p-ethyl is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the 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 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, 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. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. 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. 

Quizalofop-p-ethyl is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Accordingly, as part of registration review, EPA will issue 

future EDSP orders/data call-ins, requiring the submission of EDSP screening assays for

quizalofop-p-ethyl. For further information on the status of the EDSP, the policies and 

procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening 

battery, please visit our website: http://www.epa.gov/endo/.

Spatial Analysis

Data are not available for the percent of cropped areas and changes in crops (e.g., crop 

rotation or permanent shifts) over time. This remains an uncertainty, particularly for the 

proximity analysis for listed species. Additionally, future expansions in the use of 

quizalofop-p-ethyl are not considered. For example, many labels have geographical 

restrictions (e.g., ryegrass grown for seed in Minnesota). Likewise, expansions to other crops 

(e.g., expansion to use on herbicide-tolerant field corn; current label only allows herbicidetolerant field corn grown for seed). As labels change and uses are expanded, the result may 

be a larger geographical area in which quizalofop-p-ethyl can be used. 
136

References

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Pesticides in Pesticide Toxicology Reviews 100: 33-73.

Beyer, W.N., E. Connor, and S. Gerould. 1994. Estimates of soil ingestion by wildlife. 

Journal of Wildlife Management, 58:375-382.

Fletcher, J., Nellessen, J., & Pfleeger, T. (1994). Literature review and evaluation of the 

EPA Food-Chain (Kenaga) Nomogram, an Instrument for Estimating Pesticide Residues 

on Plants. Environ. Tox. Chem., 13, 1383-1391.

Hoerger, F., & Kenaga, E.E.. (1972). Pesticide residues on plants: Correlation of 

representative data as a basis for estimation of their magnitude in the environment. In F. 

Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, 

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

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Crop Protection Council, 49 Downing St, Farnham, Survey GU9 7PH, United Kingdom

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Handbook, Volume I of II. Office of Research and Development, Washington, DC. 

EPA/600/R-93/187a.

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Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental 

Protection Agency, Endangered and Threatened Species Effects Determination. Office of 

Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, 

D.C., January 23, 2004.

United States Environmental Protection Agency (EPA). 2007. EFED problem formulation 

for quizalofop-p-ethyl registration review PC code: quizalofop-ethyl (PC 128711) and 

quizalofop-p-ethyl (128709) DP Barcode: D344060, D544156. Environmental Fate ane 

Effects Division, Office of Pesticide Programs, United States Environmental Protection 

Agency.

United States Environmental Protection Agency (EPA). 2008. Quizalofop final work plan 

registration review. Office of Pesticide Programs, United States Environmental 

Protection Agency.
137

United States Environmental Protection Agency (EPA). 2011a. EFED environmental risk 

assessment of proposed label for Assure II (quizalofop-p-ethyl), new uses on rapeseed 

subgroup 20a, sorghum containing the DupontTM InzenTM AII herbicide tolerance trait, 

and corn containing DAS-4027809 (amended). Environmental Fate and Effects Division, 

Office of Pesticide Programs, United States Environmental Protection Agency.

United States Environmental Protection Agencye (EPA). 2011b. Quizalofop-p-ethyl 

screening level usage analysis (SLUA). Biological and Economic Analysis Division, 

Office of Pesticide Programs, United States Environmental Protection Agency.

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

Final Draft. March 1998.
138

Appendix A – Bibliography of MRIDs

Ecological Effects Studies

MRID 00128207. Cameron, B.; McDougall, J.; Craig, W.; et al. (1982) The Determina- tion 

of the Acute Toxicity (LC50) of NC 302 to Fish (96 Hours, Static): Report No. 2461. 

(Unpublished study received May 2, 1983 under 352-EX-112; prepared by Inveresk 

Research Interna- tional, Scot., submitted by E.I. du Pont de Nemours & Co., Inc., 

Wilmington, DE; CDL:250071-L)

MRID 00128208. Hutton, D.; Hall, C. (1983) 96-hour LC50 to Bluegill Sunfish: ?INY6202-6: Haskell Laboratory Report No. 17-83. (Unpublished study received May 2, 1983 

under 352-EX-112; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, DE; 

CDL:250071-M) 

MRID 00128209. Cameron, B.; McDougall, J.; Craig, W.; et al. (1983). The Determination 

of the Acute Toxicity (LC50) of NC 302 to Daphnia (96 Hours): Report No. 2460. 

(Unpublished study received May 2, 1983 under 352-EX-112; prepared by Inveresk 

Research Interna- tional, Scot., submitted by E.I. du Pont de Nemours & Co., Inc., 

Wilmington, DE; CDL:250071-N) 

MRID 00128210. Cameron, B.D., and J. McDougall. 1982. The Determination of the 

Acute Toxicity (LD50) of NC 302 to Birds Single Oral Administration (Capsule). 

Unpublished study performed by Inveresk Research International, Musselburgh, 

Scotland. Laboratory Project No. 130194. Study sponsored by Nissan Chemical 

Industries Limited, Chiyoda-ku, Tokyo, Japan. Study initiated August 25, 1982 and 

submitted November 1982. 

MRID 00128211. Cameron, B.; McDougall, J.; Dick, A.; et al. (1983) The Determina- tion 

of the Short Term Cumulative (Sub-acute) Toxicity of NC 302 to Birds: Dietary 

Administration: Report No. 2446. (Unpublished study received May 2, 1983 under 352-

EX-112; prepared by Inver- esk Research International, Scot., submitted by E.I. du Pont 

de Nemours & Co., Inc., Wilmington, DE; CDL:250071-P) 

MRID 00146680. Hall, C. (1984) 96-Hour LC50 to Rainbow Trout: INY-6202-15: Report 

No. 466-84. Unpublished study prepared by E. I. du Pont de Nemours & Co., Inc. 7 p. 

MRID 00146951. Wetzel, J. (1985). 48-Hour EC50 to Daphnia magna: NC-302 Technical 

and DPX-Y6202: Haskell Laboratory Report No. 458-84. Unpub- lished study prepared 

by E. I. du Pont de Nemours and Co, Inc. 7 p. 

MRID 00147574. Beavers, J.B., and M. Jaber. 1984. A Dietary LC50 Study in the 

Bobwhite with H # 15,562. Unpublished study performed by Wildlife International Ltd., 

St. Michaels, Maryland. Laboratory Report Number 12-158. Study sponsored by E.I. du 

Pont de Nemours & Co., Newark, DE. Study initiated October 2, 1984 and submitted 

December 10, 1984. 
139

MRID 00150109. Hutton, D. (1985) Early Life Stage Toxicity of Propanoic Acid, 2- [4-(6-

Chloroquinoxalin-2-yloxy)phenoxy]-, Ethyl Ester to Fathead Minnow: Haskell 

Laboratory Report No. 164-85: Medical Research Project No. 4581-253. Unpublished 

study prepared by E. I. du Pont de Nemours & Co., Inc. 23 p.

MRID 00150942. Meade, Alston B. 1984. Acute Contact LD50 Toxicity Study in Honey 

Bees (Apis mellifera) with INY6202. Laboratory report number ABM-84-1. 

Unpublished study by E.I. Du Pont De Nemours and Co., Wilmington, DE, sponsored by 

E.I. Du Pont De Nemours and Co., Wilmington, DE.

MRID 00153351. Mullin, L. 1985. Two-generation reproduction study in rats with INY6202 (HLR-633-85): Report number 633-85. Unpublished study prepared by Haskell 

Laboratory for Toxicology and Industrial Medicine. E. I du Pont de Nemours & Co., 

Newark, DE. 

MRID 40242204. Ward, T. (1986) Acute Toxicity of Haskell Sample #15,889 to Mysids 

Mysidopsis bahia: Report No. HLO-564-85. Rev. Unpublished study prepared by 

ERCO/A Division ENSEC Inc. 19 p.

MRID 40242205. Barrows, M.E. 1987. Acute toxicity of H-16,481 to mysid shrimp 

(Mysidopsis bahia). Laboratory report number HLO 100-87. Unpublished study 

prepared by Battelle, New England Marine Research Lab. Sponsored by E. I. DuPont de 

Demours & Company, Newark, DE.

MRID 40242207. Barrows, M. (1986) The Oyster Shell Deposition Test to Assess the Acute 

Effects of H-16,481 on Eastern Oysters (Crassostrea virgi- nica): Project No. N-0799-

8303. Unpublished study prepared by Battelle, New England Marine Research Lab. 27 p. 

MRID 43235602. Hughes, J.S. and T.L. Williams. 1994. Quizalofop-p-ethyl (DPX 79376): 

Toxicity to Anabaena flos-aquae. Unpublished study performed by Malcolm Pirnie, Inc., 

Tarrytown, NY. Laboratory report number B382-167-2. Study sponsored by E.I. du 

Pont de Nemours and Company, Agricultural Products, Wilmington, DE. Study 

completed April 26, 1994.

MRID 43270901. Hughes, J.; Williams, T. (1994) Quizalofop-p-ethyl (DPX 79376): 

Toxicity to Navicula pelliculosa: Lab Project Number: B382-167-3: AMR 2842-93. 

Unpublished study prepared by Malcolm Pirnie, Inc. 29 p. 

MRID 43270902. Hughes, J.S. and T.L. Williams. 1994. Quizalofop-p-ethyl (DPX 79376): 

Toxicity to Skeletonema costatum. Unpublished study performed by Malcolm Pirnie, 

Inc., Tarrytown, NY. Laboratory report number B382-167-4. Study sponsored by E.I. du 

Pont de Nemours and Company, Agricultural Products, Wilmington, DE. Study 

completed May 16, 1994.
140

MRID 46607101. Frey, L., K. Martin, J. Beavers, et al. 1999. Quizalofop-p-ethyl: a 

reproduction study with the northern bobwhite. Project number: 

221/112,071598/QR/WC/SUB221. Unpublished study prepared by Wildlife 

International, Ltd.

MRID 46607102. Frey, L., K. Martin, J. Beavers, et al. 1999. Quizalofop-p-ethyl: a 

reproduction study with the mallard. Project number: 

221/113,071598/MR/WC/SUB221. Unpublished study prepared by Wildlife 

International, Ltd.

MRID 47408402. Croudace, C.P. 1992. Quizalofop-Ethyl Technical D+ Isomer: Acute 

Toxicity to Rainbow Trout (Oncorhynchus mykiss). Unpublished study performed by 

Imperial Chemical Industries PLC, Brixham Devon TQ5 8BA, UK, Laboratory report 

number W326/C. Study sponsored by Schering Agrochemicals Ltd., Chesterford Park 

Research Station, Saffron Walden, Essex CB10 1XL, UK. Study completed May 1, 1992

MRID 47408405. Jenkins, C. (1997) Quizalofop-P: Acute Toxicity to Rainbow Trout: 

Determination of 96-Hour (Lethal Concentrations 50): Final Report. Project Number: 

NAS/213, NAS213/970303, 970303. Unpublished study prepared by Huntingdon Life 

Sciences, Ltd. 28 p.

MRID 47408407. Jenkins, C.A. 1997. Quizalofop-P: Acute toxicity to Daphnia magnaDetermination of 48-hour EC50 under static conditions. Unpublished study performed by 

Huntingdon Life Sciences Ltd., Suffolk, England. Laboratory report number 

NAS214/970304. Study sponsored by Nissan Chemical Industries, Ltd., Agricultural 

Division, Tokyo, Japan. Study completed June 6, 1997.

MRID 47408409. Jenkins, C.A. 1999. Quizalofop-P: Daphnia Magna Reproduction Test 

Final Report. Unpublished study performed by Huntingdon Life Sciences Ltd., Eye, 

Suffolk, England. Laboratory Study No. NAS240. Study sponsored by Nissan Chemical 

Industries, Ltd., Chiyoda-ku, Tokyo, Japan. Study initiated October 20, 1998 and 

submitted February 25, 1999. 

MRID 47408410. Sowig, P. and H. Gosch. 2002. Acute toxicity to Daphnia magna

(Waterflea) under static testing conditions- Quizalofop-P-ethyl 50 g ai/L EC. 

Unpublished study performed by Bayer CropScience GmbH, Ecotoxicology, D-65926 

Frankfurt am Main, Federal Republic of Germany. Laboratory report number CE02/019. 

Study sponsored by Nissan Chemical Industries, Ltd., Tokyo, Japan. Study completed on 

October 31, 2002.

MRID 47408411. Spatz, B. 2003. Effects of Targa Super (Quizalofop-P-ethyl 50 g/L EC) 

on Terrestrial (Non-Target) Plants: Seedling Emergence and Seedling Growth Test. 

Unpublished study performed by Institut fur Biologische Analytik und Consulting 

IBACON GmbH, Rossdorf, Germany. Laboratory Project No.: 13841086. Study 

submitted by Nissan Chemical Industries, Ltd, Tokyo, Japan. Study completed January 

30, 2003. 
141

MRID 47408412. Spatz, B. (2003) Effects of Targa Super (Quizalofop-P-Ethyl 50 g/L EC) 

on Terrestrial (Non-Target) Plants: Vegetative Vigour Test: Final Report. Project 

Number: 13842087. Unpublished study prepared by Institut fuer Biologische Analytik 

und Consulting IBACON. 64 p.

MRID 47408413. Sowig, P.; Gosch, H. (2002) Acute Toxicity to Oncorhynchus mykiss 

(Rainbow Trout) Under Static Testing Conditions: Quizalofop-P-Ethyl 50g ai/L EC. 

Project Number: CE02/018. Unpublished study prepared by Bayer Cropscience Gmbh. 

33 p.

MRID 47910501. Jenkins, C.A. 1999. Quizalofop-P: Daphnia magna Reproduction Test. 

Unpublished study performed by Huntington Life Sciences Ltd., Suffolk, England. 

Laboratory Report No. NAS240/992114. Study sponsored by Nissan Chemical 

Industries, Ltd., Chiyoda-ku, Tokyo, Japan. Final report submitted February 25, 1999. 

MRID 47910503. Minderhout, T., J.A. MacGregor, and H.O. Krueger. 2009. QuizalofopP-Ethyl: An Early Life-Stage Toxicity Test with the Sheepshead Minnow (Cyprinodon 

variegatus). Unpublished study performed by Wildlife International, Ltd., Easton, MD. 

Laboratory Project No. 221A-101. Study submitted by Nissan Chemical Industries, Ltd., 

Chiyoda-ku, Tokyo, Japan. Study initiated October 17, 2007 and completed June 1, 

2009. 

MRID 47910505. Porch, J.R., Martin, K.H., and Krueger, H.O. 2009. Quizalofop-P-ethyl 

10.3% EC (Targa): A toxicity test to determine the effects of the test substance on 

vegetative vigor of ten species of plants. Unpublished study performed by Wildlife 

International, Ltd., Easton, Maryland. Laboratory Project Number: 221-116. Study 

sponsored by Nissan Chemical Industries, Ltd., Tokyo, Japan. Study completed July 23, 

2009.

MRID 48037501. Jenkins, C.A. 1997. Quizalofop-P: Determination of 72-hour EC50 to 

Selenastrum capricornutum. Unpublished study performed by Huntingdon Life Sciences 

Ltd., Suffolk, England. Laboratory project no.: NAS212/970302. Study sponsored by 

Nissan Chemical Industries, Ltd., Tokyo, Japan. Study completed June 6, 1997.

MRID 48037504. Cockroft, R. 2004. Quizalofop-P-Ethyl: Higher Plant (Lemna) Growth 

Inhibition Test. Unpublished study performed by Huntingdon Life Sciences Ltd., 

Cambridgeshire, England. Laboratory project no.: NAS/647. Study sponsored by Nissan 

Chemical Industries, Ltd., Chiyoda-ku, Tokyo, Japan. Study completed October 29, 

2004.

MRID 48038101. Friedrich, Sabine. 2009. Terrestrial (non-target) plant test with 

Quizalofop-P-Ethyl 5% EC: Seedling emergence and seedling growth test. Unpublished 

study performed by BioChem agrar, Gerichshain, Germany. Laboratory project no.: 08 

10 48 012 S. Study sponsored by Sharda Worldwide Exports Pvt. Ltd., Mumbai, India. 

Study completed March 31, 2009.
142

MRID 48038102. Friedrich, S. (2009) Terrestrial (Non-Target) Plant Test with QuizalofopP-Ethyl 5% EC: Vegetative Vigour Test: Final Report. Project Number: 08/10/48/013/S. 

Unpublished study prepared by Biochem Agrar, Labor fuer Biologische und Chemische. 

79 p.

MRID 48041401. Sloman, T.; Leva, S. (1998) Quizalofop P-Ethyl 10.9% EC Formulation: 

Influence on Growth and Growth Rate of the Green Alga Selenastrum Capricornutum. 

Project Number: AMR/4468/97, MR/11401. Unpublished study prepared by E.I. du Pont 

de Nemours and Company. 33 p.

MRID 48356801. Porch, J.R. and T.Z. Kendall. 2011. Quizalofop P-Ethyl (DPX-79376) 

10EC: A Greenhouse Study to Investigate the Effects on the Vegetative Vigor of an 

Emergent Macrophyte under Static-Renewal Conditions. Unpublished study performed 

by Wildlife International, Ltd., Easton, Maryland. Study Project Number: 112-671. 

Study sponsored by E.I. du Pont de Nemours and Company, Wilmington, Delaware and 

Nissan Chemical Industries, Ltd., Chiyoda-ku, Tokyo, Japan. Study completed January 

14, 2011.

MRID 48417901. Bomke, C. 2008. Early-Life Stage Toxicity of Fenoxaprop-P-ethyl 

(technical) to Fish (Pimephales promelas). Unpublished study performed by Bayer 

CropScience AG, Development-Environmental SafetyEcotoxicology (BCS-D-EnSaETX), 40789. Monheim am Rhein, Germany. Laboratory Study Number: EBFPL009. 

Study sponsored/submitted by Bayer CropSciences AG. Study initiated on Nov 15, 2010 

and completed on March 8, 2011 (MRID 484179-01).

MRID 48492501. Bomke, C. 2011. Acute toxicity of fenoxaprop-p-ethyl to fish (Pimphales 

promelas) under flow-through conditions. Laboratory project number: EBFPL012/E 280 

3970-9. Bayer CropScience AG Development – Environmental Safety – Ecotoxicoloty, 

Monheim, Germany.

Environmental Fate Studies

Quizalofop-p-ethyl Studies (PC 128709)

MRID 43235603. McMillan, J. (1994) Aerobic Soil Metabolism of (Quinoxaline(U)-(carbon 

14))Quizalofop P-Ethyl: Lab Project Number: AMR 2656-93. Unpublished study 

prepared by E. I. du Pont de Nemours & Co., Global Technology Div. 76 p.

MRID 47408414. Farrell, P. (2003) Quizalofop-P-Ethyl: Terrestrial Field Dissipation Study 

with Quizalofop-P-Ethyl 50g AS/L EC Applied to Bare Soil in the United Kingdom, 

Germany, Spain and South France, 2001/2002. Project Number: NAS/347/024371, 

NAS/347. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 149 p.
143

MRID 47408415. Farrell, P. (2003) Quizalofop-P-Ethyl: Terrestrial Field Dissipation Study 

with Quizalofop-P-Ethyl 50 G ASL EC Applied to Bare Soil in the United Kingdom, 

Germany, Spain and South France, 2001/2002 (Report Amendment 1). Project Number: 

NAS/347/024371, NAS/347. Unpublished study prepared by Huntingdon Life Sciences, 

Ltd. 16 p.

MRID 47408416. Farrell, P. (2003) Quizalofop-P-Ethyl: Terrestrial Field Dissipation Study 

with Quizalofop-P-Ethyl 50 G AS/L EC Applied to Bare Soil in Spain, 2002. Project 

Number: NAS/404/033001, NAS/404. Unpublished study prepared by Huntingdon Life 

Sciences, Ltd. 97 p.

MRID 47408417. Tate, S. (2003) Quizalofop-P-Ethyl: Development and Validation of 

Methodology for the Determination of Residues of Quizalofop-P-Ethyl and Its Two 

Major Metabolites Quizalofop and 3-OH-Quizalofop in Soil. Project Number: 

NAS/351/022689, NAS/351. Unpublished study prepared by Huntingdon Life Sciences 

Ltd. 119 p.

Quizalofop-ethyl Studies (PC 128711)

MRID 00128214. Cadwgan, G. (1983) Hydrolysis of [14C]-quinoxaline-labeled DPXY6202: Document No. AMR-127-83. (Unpublished study received May 2, 1983 under 

352-EX-112; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, DE; 

CDL:250071-S)

MRID 00131585. E.I. du Pont de Nemours & Co., Inc. (1983) (Study--Residue: DPXY6202 on Soybeans and Other Rotational Crops). (Compilation; unpublished study 

received Oct 14, 1983 under 352-EX-115; CDL: 072026-B)

MRID 00146693. Ryan, D. (1984?) Photolysis of [Carbon 14]-DPX-Y6202 in Water: AMR275-84. Unpublished study prepared by E. I. du Pont de Nemours & Co., Inc. 19 p.

MRID 00146694. Wakabayashi, T.; Hirata, H.; Takano, S. (1985) Environmental Chemistry of NC-302--Photolysis of NC-302 on Soil. Unpublished study prepared by Nissan 

Chemical Industries, Ltd. 14 p.

MRID 00146948. Ryan, D. (1985) Photodegradation of [Quinoxaline-[Carbon 14]] DPXY6202 on Soil: Document No. AMR-289-84. Unpublished study pre- pared by E. I. du 

Pont de Nemours & Co., Inc. 21 p.

MRID 40336002. Ryan, D.; Atkins, B. (1986) Photodegradation of [Phenyl(U)-[Carbon 14] 

DPX-Y6202 and [Quinoxaline(U)-[Carbon 14] DPX-Y6202 on Soil: Laboratory Project 

ID: AMR-576-86. Unpublished study prepared by E. I. du Pont de Nemours & Co., Inc. 

38 p.
144

MRID 00128213. Nissan Chemical Industries, Ltd. (19??) Aerobic Soil Metabolism of 

[

14C]-phenyl-labeled DPX-Y6202: ?Submitter| Document No. AMR- 126-83. 

(Unpublished study received May 2, 1983 under 352-EX- 112; submitted by E.I. du Pont 

de Nemours & Co., Inc., Wilming- ton, DE; CDL:250071-R)

MRID 00131585. E.I. du Pont de Nemours & Co., Inc. (1983) (Study--Residue: DPXY6202 on Soybeans and Other Rotational Crops). (Compilation; unpublished study 

received Oct 14, 1983 under 352-EX-115; CDL: 072026-B)

MRID 00146695. Cadwgan, G.; McFetridge, R. (1985?) Aerobic Soil Metabolism of 

[Phenyl-[carbon 14](U)] DPX-Y6202: AMR-329-85. Unpublished study prepared by E. 

I. du Pont de Nemours & Co., Inc. 43 p.

MRID 00146696. Hirata, H.; Wakabayashi, T.; Takano, S.; et al. (1985) Environmen- tal 

Chemistry of NC-302--Degradation of NC-302 in Soil. Unpub- lished study prepared by 

Nissan Chemical Industries, Ltd. 27 p.

MRID 00150937. Cadwgan, G. (1984) Aerobic Soil Metabolism of [Carbon-14-Quinoxaline-Labeled]-DPX-Y6202. Unpublished study prepared by E.I. du- Pont de Nemours and 

Co. Inc. 46 p.

MRID 00146696. Hirata, H.; Wakabayashi, T.; Takano, S.; et al. (1985) Environmental 

Chemistry of NC-302--Degradation of NC-302 in Soil. Unpub- lished study prepared by 

Nissan Chemical Industries, Ltd. 27 p.

MRID 00146697. Cadwgan, G.; McFetridge, R. (1985?) Anaerobic Aquatic Metabolism of 

[Quinoxaline-carbon 14] DPX-Y6202 and [Phenyl-carbon 14(U)] DPX- Y6202: AMR350-85. Unpublished study prepared by E. I. du Pont de Nemours & Co., Inc. 51 p.

MRID 00146698. Priester, T. (1985?) Batch Equilibrium (Absorption/Desorption) and Soil 

Thin-layer Chromatography Studies with [Quinoxaline-phenyl- carbon 14(U)] DPXY6202: AMR-314-85. Unpublished study prepared by E. I. du Pont de Nemours & Co., 

Inc. 32 p.

MRID 00146700. Wakabayashi, T.; Hirata, H.; Takano, S. (1985) Environmental Chemistry of NC-302--Soil Adsorption and Desorption of NC-302 in Soil. Unpublished study 

prepared by Nissan Chemical Industries, Ltd. 17 p.

MRID 00146699. Wakabayashi, T.; Hirata, H.; Takano, S. (1985) Environmental Chemistry 

of NC-302--Mobility of NC-302 in Soil. Unpublished study prepared by Nissan Chemical 

Industries, Ltd. 20 p.

MRID 00146947. Priester, T. (1985) Batch Equilibrium (Adsorption/Desorption) and Soil 

Thin-Layer Chromatography Studies with [Quinoxaline-[Carbon 14]] 2-[4-(6-

Chloroquinoxalin-2-yloxy)Phenoxy] Propanoic Acid ("DPX-Y6202 Acid"): Document 
145

No. AMR-336-85. Unpublished study prepared by E. I. du Pont de Nemours & Co., Inc. 

57 p.

MRID 00146949. Monson, K. (1985) Soil Column Leaching Behavior of [Quinoxaline-

[Carbon 14]] DPX-Y6202: Document No. AMR-357-85. Unpublished study prepared by 

E. I. du Pont de Nemours & Co., Inc. 30 p.

MRID 00146698. Priester, T. (1985?) Batch Equilibrium (Absorption/Desorption) and Soil 

Thin-layer Chromatography Studies with [Quinoxaline-phenyl- carbon 14(U)] DPXY6202: AMR-314-85. Unpublished study prepared by E. I. du Pont de Nemours & Co., 

Inc. 32 p.

MRID 00128215. E.I. du Pont de Nemours & Co., Inc. (1983) [Soil Recovery Analyses: 

DPX-Y6202]. (Unpublished study received May 2, 1983 under 352- EX-112; 

CDL:250071-T)

MRID 00146950. Cadwgan, G.; Atkins, B. (1985) Field Soil Dissipation [Phenyl-[Carbon 

14](U)] and [Quinoxaline-[Carbon 14]] DPX-Y6202 in Delaware, North Carolina, 

Illinois and Mississippi: Document No. AMR-333- 85. Unpublished study prepared by E. 

I. du Pont de Nemours & Co., Inc. 39 p.

MRID 40336001. Ryan, K. (1987) Field Dissipation of DPX-Y6202 (Assure): Laboratory 

Project ID: AMR-921-87. Unpublished study prepared by Bio- spherics Inc. 191 p.

MRID 00131583. Hutton, D.G. 1983. DPX-Y6202 Residue studies with Bluegill sunfish.
146

Appendix B – Aryloxyphenoxypropionate Chemical Family (“FOPs”)

Table B-1. Structures of the Aryloxyphenoxypropionate Chemical Family parents and corresponding 

primary degradate, which is the active ingredient.

Parent Primary Degradate (Active Ingredient)

Clodinafop-propargyl Clodinafop

Cyhalofop-butyl Cyhalofop

Diclofop-methyl Diclofop

Fenoxaprop-P-ethyl Fenoxaprop-P

Fluazifop-P-butyl Fluazifop-P

Haloxyfop-R-methyl Haloxyfop-R

Propaquizafop Quizalofop

Quizalofop-P-ethyl Quizalofop

Based on pesticides included as aryloxyphenoxypropionate herbicides 

(http://pested.okstate.edu/pdf/herbicide%20moa.pdf).

N O

O C

H

CH3

C

O

O

Cl F C

H2

C CH

N O

O C

H

CH3

C

O

OH Cl F

O

O C

H

CH3

C

O

O

C F C

H2

H2

C C

H2

N

CH3

O

O C

H

CH3

C

O

OH N C F

O

O C

H

CH3

C

O

O

Cl Cl CH3

O

O C

H

CH3

C

O

OH Cl Cl

O

O C

H

CH3

C

O

O C

H2

CH3

O

N

Cl

O

O C

H

CH3

C

O

OH

O

N

Cl

N

O

O C

H

CH3

C

O

O

F3C

C

H2

H2

C C

H2

CH3

N

O

O C

H

CH3

C

O

OH F3C

N O

O C

H

CH3

C

O

O

F3C Cl CH3

N O

O C

H

CH3

C

O

OH F3C Cl

N

N

Cl

O

O C

H

CH3

C

O

O

H2

C

C

H2

O N C

CH3

CH3

N

N

Cl

O

O C

H

CH3

C

O

OH

N

N

Cl

O

O C

H

CH3

C

O

O C

H2

CH3

N

N

Cl

O

O C

H

CH3

C

O

OH
147

Appendix C – Chemical Structures and Maximum Degradate 

Formation

Table C-1. Chemical Names and Structures of Quizalofop-P-Ethyl and its Degradates

Chemical Name Structure

Quizalofop-p-ethyl

IUPAC name: ethyl (R)-2-[4-(6-

chloroquinoxalin-2-

yloxy)phenoxy]propionate

CAS name: ethyl (2R)-2-[4-[(6-

chloro-2-

quinoxalinyl)oxy]phenoxy]propanoate

Quizalofop acid

IUPAC name: (RS)-2-[4-(6-

chloroquinoxalin-2-

yloxy)phenoxy]propionic acid

CAS name: 2-[4-[(6-chloro-2-

quinoxalinyl)oxy]phenoxy]propanoic 

acid

3-OH-quizalofop acid

CAS name: (R)-2-[4-(6-chloro-3-

hydroxyquinoxalin-2-

yloxy)phenoxy]propionic acid

Phenol 1

Hydroxylated Phenol 1

Phenol 2

Hydroxy phenol 2

CAS name: 6-chloroquinoxaline-2,3-

diol

N

N

Cl

O

O C

H

CH3

C

O

O C

H2

CH3

N

N

Cl

O

O C

H

CH3

C

O

OH N

N

Cl

O

O C

H

CH3

C

O

OH

HO

N

N

Cl

O

OH

N

N

Cl

O

OH

HO

N

N

Cl

OH

N

N

Cl

OH

HO
148

Chemical Name Structure

Phenol 3

Phenol 4

HO

O C

H

CH3

C

O

O C

H2

CH3

HO

O C

H

CH3

C

O

OH
149

Table C-2. Maximum Reported Amounts of Quizalofop-p-ethyl Degradation Products.

Degradate

Maximum % of Applied 

(μg/L or μg/kg in Field 

Studies) Study Type MRID

Quizalofop acid Laboratory studies

~100%

4.1% (28 d)

7.2% (15 d)

78.3% (2 d)

62.6% (15 d)

80.2% (2 d)

51% of residues in viscera

Hydrolysis

Aqueous photolysis

Soil photolysis

Aerobic soil metabolism

Aerobic soil metabolism

Anaerobic soil metabolism

Fish bioaccumulation

00131583

00146693

40336002

00146695

43235603

00146697

00131583

Terrestrial field dissipation studies

79.7 ng/g Southern France Soil 474084146

3-OHquizalofop acid

Laboratory studies

20.8% (60 d) Aerobic soil metabolism 43235603

Terrestrial field dissipation studies

5.4 ng/g United Kingdom Soil 474084146

Phenol 1 Laboratory studies

5.1% (28 d)

6.1% (24 d)

2.3% (30 d)

9.5% (52 d)

Aqueous photolysis

Aerobic soil metabolism

Aerobic soil metabolism

Anaerobic soil metabolism

00146693

00146695

43235603

00146697

Phenol 2 Laboratory studies

2.7% (22 d)

5.0% (60 d)

13.2% (6 d)

Aqueous photolysis

Aerobic soil metabolism

Anaerobic soil metabolism

00146693

43235603

00146697

Hydroxy phenol 

2

Laboratory studies

11.2% (91 d)

25.4% (52 d)

Aerobic soil metabolism

Anaerobic soil metabolism

43235603

00146697

Phenol 3 Laboratory studies

2.0% (53 d) Aerobic soil metabolism 00146695

Phenol 4 Laboratory studies

31.1% (5 d) Aerobic soil metabolism 00146695

Unextracted 

Residue

Laboratory studies

29.9% (53 d)

26.6% (91 d)

34.0% (30 d)

Aerobic soil metabolism

Aerobic soil metabolism

Anaerobic soil metabolism

00146695

43235603

00146697

Carbon Dioxide Laboratory studies

22.3% (32 d)

41.1% (53 d)

8.3% (91 d)

Soil photolysis

Aerobic soil metabolism

Aerobic soil metabolism

40336002

00146695

43235603

d = days; m = months
150
151

Appendix D – ECOTOX Literature Search

Papers That Were Accepted

Ahemad, M. and Khan, M. S. Toxicity Assessment of Herbicides Quizalafop-p-Ethyl and Clodinafop Towards 

Rhizobium Pea Symbiosis. BCM,GRO,REPSOIL,ENV; 2009; 82, (6): 761-766. 

Notes: EcoReference No.: 150237

Chemical of Concern: QZFPE

Rejected because units were not convertable to lb ai/A.

De, R. K.; Mandal, R. K.; Sarkar, S., and Ghorai, A. K. Non-Target Effect of Herbicides on Macrophomina 

phaseolina Causing Stem Rot of Jute. POPENV; 2007; 25S, (2): 475-478. 

Notes: EcoReference No.: 100606

Chemical of Concern: QZFE,TFN

Rejected because the units are not convertable to lb ai/A

Dear, B. S.; Sandral, G. A., and Wilson, B. C. D. Tolerance of Perennial Pasture Grass Seedlings to Pre- and 

Post-Emergent Grass Herbicides. GRO,PHYSOIL,ENV; 2006; 46, (5): 637-644. 

Notes: EcoReference No.: 86670

Chemical of Concern: 

ATZ,CLT,CSF,CZE,DFPM,FNPPE,FZFB,MBZ,PDM,PZM,QZFE,SXD,SZ,TFN,TKY,TRL,TS

F

Rejected because the units are not convertible to lb ai/A

Eleftherohorinos, I. G. and Dhima, K. V. Red Rice (Oryza sativa) Control in Rice (O. sativa) with 

Preemergence and Postemergence Herbicides. POPAQUA; 2002; 16, (3): 537-540. 

Notes: EcoReference No.: 95840

Chemical of Concern: ACO,ACR,DMM,GFS,GYP,MTL,PQT,QZFE

Rejected because the test duration was too long.

Hall, L. M.; Moss, S. R., and Powles, S. B. Mechanisms of Resistance to Aryloxyphenoxypropionate 

Herbicides in Two Resistant Biotypes of Alopecurus myosuroides (Blackgrass): Herbicide 

Metabolism as a Cross-Resistance Mechanism. GROSOIL,ENV; 1997; 57, (2): 87-98. 

Notes: EcoReference No.: 108307

Chemical of Concern: DFPM,FNPE,QZFE,SXD,TKY

Rejected because an EC25 endpoint was needed

Heap, I. M. and Morrison, I. N. Resistance to Aryloxyphenoxypropionate and Cyclohexanedione Herbicides in 

Green Foxtail (Setaria viridis). GRO,POPSOIL,ENV,MIXTURE; 1996; 44, (1): 25-30. 

Notes: EcoReference No.: 120407

Chemical of Concern: CLFP,CLT,CTL,DFPM,EFL,FNPPE,QZFE,SXD,TKY

Rejected because an EC25 endpoint was needed

Kuk, Y. I.; Wu, J.; Derr, J. F., and Hatzios, K. K. Mechanism of Fenoxaprop Resistance in an Accession of 

Smooth Crabgrass (Digitaria ischaemum). ACC,BCM,GROSOIL,ENV; 1999; 64, (2): 112-123. 

Notes: EcoReference No.: 109535

Chemical of Concern: FNPE,FNPPE,QZFPE,SXD
152

Rejected because the endpoint was not an EC25

Matthews, N.; Powles, S. B., and Preston, C. Mechanisms of Resistance to Acetyl-Coenzyme A CarboxylaseInhibiting Herbicides in a Hordeum leporinum Population. ACC,BCM,MORSOIL,ENV; 2000; 

56, 441-447. 

Notes: EcoReference No.: 63953

Chemical of Concern: CLT,DFP,FZFB,QZFPE,SXD,TKY

Rejected because the endpoint was not an EC25

Pannacci, E.; Graziani, F., and Covarelli, G. Use of Herbicide Mixtures for Pre and Post-Emergence Weed 

Control in Sunflower (Helianthus annuus). PHY,POPSOIL,ENV,MIXTURE; 2007; 26, (8): 

1150-1157. 

Notes: EcoReference No.: 101888

Chemical of Concern: FFC,LNR,MTC,OXF,PDM,QZFPE

Rejected because it was not the lowest endpoint

Rea, B. L.; Mayes, A. J., and Marshall, J. FBC 32197 for Annual and Perennial Grass Weed Control in Oilseed 

Rape. POPSOIL,ENV,MIXTURE; 1984; 6, 191-198. 

Notes: EcoReference No.: 31475

Chemical of Concern: CPR,FZFB,QZFE

Rejected because the test duration was too long

Sakata, G.; Makino, K.; Kusano, K.; Satow, J.; Ikai, T., and Suzuki, K. Preparation of Optically Pure Ethyl (R)-

(+) and (S)-(-)-2-(4-(6-Chloro-2-Quinoxalinyloxy)Phenoxy]Propanoate by Resolution Method 

and Their Herbicidal Activities. GROSOIL,ENV; 1985; 10, 75-79. 

Notes: EcoReference No.: 100574

Chemical of Concern: QZFE,QZFPE

Rejected because the units were not convertible to lb ai/A

Sakata, G.; Makino, K.; Morimoto, K.; Ikai, T., and Hasebe, S. Synthesis and Herbicidal Activity of Optically 

Active Ethyl 2-[4-(6-Chloro-2-Quinoxalinyloxy)Phenoxy]Propanoate. GROSOIL,ENV; 1985; 

10, (1): 69-73. 

Notes: EcoReference No.: 100572

Chemical of Concern: QZFE,QZFPE

Rejected because the units were not convertible to lb ai/A

Soltani, N.; Robinson, D. E.; Shropshire, C., and Sikkema, P. H. Adzuki Bean (Vigna angularis) Responses to 

Post-Emergence Herbicides. BCM,GRO,PHY,POPSOIL,ENV,MIXTURE; 2006; 25, (6): 613-

617. 

Notes: EcoReference No.: 100593

Chemical of Concern: BT,FSF,IZX,QZFPE,SXD

Rejected because there was already a lower endpoint

Zhang, X.; Wang, S.; Wang, Y.; Xia, T.; Chen, J., and Cai, X. Differential Enantioselectivity of Quizalofop 

Ethyl and Its Acidic Metabolite: Direct Enantiomeric Separation and Assessment of Multiple 

Toxicological Endpoints. PHY,POPAQUA; 2011; 186, (1): 876-882. 

Notes: EcoReference No.: 154896

Chemical of Concern: QZFE,QZFPE
153

Rejected because it was not the lowest endpoint

Papers That Were Not Accepted

Accepted for EcoTox but not OPP

De Prado, R. ; Gonzalez-Gutierrez, J.; Menendez, J.; Gasquez, J.; Gronwald, J. W., and Gimenez-Espinosa, R. 

Resistance to Acetyl CoA Carboxylase-Inhibiting Herbicides in Lolium multiflorum, 

ACC,MOR: SOIL,ENV,TOP; 2000UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 59397

Chemical of Concern: CLT,DFPM,HFPM,QZFE,SXD

Hanin, O.; Rubin, B.; Applebaum, S. W., and Rafaeli, A. Structure-Activity Relationships of Pheromonostasis 

Induced by ACCase-Inhibitor Herbicides in the Moth Helicoverpa armigera, MOR: ORAL; 

2008UR

ECOTOX,EFED,INSECT.

Notes: EcoReference No.: 154892

Chemical of Concern: DFP,DFPM,QZFE,TKY

Hautier, L.; Jansen, J. P.; Mabon, N., and Schiffers, B. Selectivity Lists of Pesticides to Beneficial Arthropods 

for IPM Programs in Carrot - First Results, MOR,POP: ENV,MIXTURE; 2005TV [Okapi]

ECOTOX,EFED,BEES,INSECT.

Notes: EcoReference No.: 104765

Chemical of Concern: 

AZX,CMZ,CPP,DFC,DM,DMT,FZFB,IPD,LCYT,LNR,MYC,PIM,PQT,PRIG,QZFPE,SFR,TE

Z

Hidayat, I. and Preston, C. Enhanced Metabolism of Fluazifop Acid in a Biotype of Digitaria sanguinalis 

Resistant to the Herbicide Fluazifop-P-Butyl, ACC,BCM,MOR. 

cpreston@walte.adelaide.edu.au//C. Preston, CRC for Weed Management Systems, Department 

of Crop Protection, University of Adelaide, Glen Osmond, SA 5064, Australia//: 

SOIL,ENV,MIXTURE,TOP; 1997UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 64594

Chemical of Concern: CLT,FZFB,HFPM,MLN,PPB,QZFPE,SXD,TKY

Kawahigashi, H.; Hirose, S.; Inui, H.; Ohkawa, H., and Ohkawa, Y. Enhanced Herbicide Cross-Tolerance in 

Transgenic Rice Plants Co-Expressing Human CYP1A1, CYP2B6, and CYP2C19, 

CEL,GRO,REP: SOIL,ENV,MIXTURE; 2005UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 115263

Chemical of Concern: ACO,MTL,NFZ,QZFE

Kawahigashi, H.; Hirose, S.; Ohkawa, H., and Ohkawa, Y. Transgenic Rice Plants Expressing Human CYP1A1 

Exude Herbicide Metabolites from Their Roots, REP: SOIL,ENV; 2003UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 101467

Chemical of Concern: ATZ,NFZ,QZFE

Kawahigashi, H.; Hirose, S.; Ohkawa, H., and Ohkawa, Y. Evaluation of Herbicide Metabolism in Transgenic 

Rice Plants Expressing CYP1A1 and CYP2B6, ACC: SOIL,ENV; 2005UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 101418

Chemical of Concern: ACO,ACR,CPP,Kusanagi, T. Herbicides: Upland Crops, NOC: 
154

SOIL,ENV,MIXTURE; 1985UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 117867

Chemical of Concern: ACR,BT,DU,FSF,LNR,MTL,ODZ,PMT,QZFE,TRB 

DU,MTL,NFZ,PDM,QZFE,TFN

Kawahigashi, H.; Hirose, S.; Ohkawa, H., and Ohkawa, Y. Transgenic Rice Plants Expressing Human P450 

Genes Involved in Xenobiotic Metabolism for Phytoremediation, GRO: SOIL,ENV; 2008UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 118859

Chemical of Concern: ACO,ACR,ATZ,DU,MTL,NFZ,QZFE,SZ,TFN

Luo, X. Y.; Sunohara, Y., and Matsumoto, H. Fluazifop-Butyl Causes Membrane Peroxidation in the HerbicideSusceptible Broad Leaf Weed Bristly Starbur (Acanthospermum hispidum), BCM,GRO,PHY. 

hmatsu@biol.tsukuba.ac.jp//H. Matsumoto, Institute of Applied Biochemistry, University of 

Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan//: SOIL,ENV; 2004UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 109549

Chemical of Concern: AVIG,FNPE,FZFB,QZFE,SXD

Makino, K.; Sakata, G.; Kawamura, Y., and Ikai, T. Quantitative Structure-Activity Relationships of 2-[4-(2-

Quinoxalinyloxy)Phenoxy]Propanoic Acid Derivatives, Using a Convenient Parameter, 

Retention Volume, in High-Performance Liquid Chromatography, GRO: SOIL,ENV; 1986UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 100573

Chemical of Concern: QZFE

Qasem, J. R. Chemical Weed Control in Seedbed Sown Onion (Allium cepa L.), POP: SOIL,ENV; 2006UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 87396

Chemical of Concern: DCPA,MBZ,ODZ,OXF,PAQT,PDM,PMT,PQT,PYZ,PZM,QZFE,TFN

Samsoe-Petersen, L. Effects of 67 Herbicides and Plant Growth Regulators on the Rove Beetle Aleochara 

bilineata (Col.: Staphylinidae) in the Laboratory, MOR,REP: ENV,MIXTURE; 1995TV 

[BMN, DPP2, EFS, FZFB, MCPA, NAA, NAD, TSF, Gallant super, quinmerac, Starane 180, rh 

0265, Goltix, Tribunil, Ustinex PA, pyridate-terbuthylazine mixt., pyridate-terbuthylazinemetolachlor mixt., fluoroglycofen, cga 1136872, Ioxynil, Faneron]

ECOTOX,EFED,INSECT.

Notes: EcoReference No.: 63490

Chemical of Concern: 

ATZ,BMC,BMN,BT,CBL,CQTC,DFPM,DMDP,DPP1,DPP2,EFS,FXP,FZFB,GFSNH,GYPI,

MCPA,MCPP1,MCPP2,MLNR,MTL,MTSM,NAA,NAD,PDM,PYD,PZM,QZFE,SZ,TKY,TSF

Schumacher, C. E. and Hatterman-Valenti, H. M. Effect of Dose and Spray Volume on Early-Season 

Broadleaved Weed Control in Allium Using Herbicides, GRO,POP: SOIL,ENV,MIXTURE; 

2007UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 154894

Chemical of Concern: BMN,CLT,MZB,OXF,PDM,QZFPE

Soltani, N.; Shropshire, C., and Sikkema, P. H. Control of Volunteer Glyphosate-Tolerant Maize (Zea mays) in 

Glyphosate-Tolerant Soybean (Glycine max), GRO,POP: SOIL,ENV; 2006UR

ECOTOX,EFED,P.

Notes: EcoReference No.: 114183

Chemical of Concern: CLT,FNPPE,GYP,QZFPE,SXD
155

Excluded

3 - Toxic and Dangerous Properties. Oxford: William Andrew Publishing; 2011: 81-213. 

Notes: Chemical of Concern: QZFPE

Aliferis, Konstantinos A. and Jabaji, Suha. Metabolomics : a robust bioanalytical approach for the discovery of 

the modes-of-action of pesticides: A review. 2011 Jun; 100, (2 ): 105-117. 

Notes: Chemical of Concern: QZFPE

Alikhanidi, Sokratis and Takahashi, Yoshimasa. Pesticide persistence in the environment - collected data and 

structure-based analysis. 2004; 3, (2): 59-70. 

Notes: Chemical of Concern: QZFPE

Appendix B - Toxicity values for five ECOTOX data sets for pesticide. Emilio Benfenati and Emilio Benfenati. 

Amsterdam: Elsevier; 2007: 323-461. 

Notes: Chemical of Concern: QZFPE

Barnwell, Philip and Cobb, Andrew H. An investigation of aryloxyphenoxypropionate antagonism of auxintype herbicide action on proton-efflux. 1993; 47, (2): 87-97. 

Notes: Chemical of Concern: QZFPE

Belfroid, A. C.; van Drunen, M.; Beek, M. A.; Schrap, S. M.; van Gestel, C. A. M., and van Hattum, B. Relative 

risks of transformation products of pesticides for aquatic ecosystems. 1998; 222, (3): 167-183. 

Notes: Chemical of Concern: QZFPE

Bolognesi, C. and Merlo, F. D. Pesticides: Human Health Effects. Editor-in-Chief:-á-áJerome O. Nriagu. 

Burlington: Elsevier; 2011: 438-453. 

Notes: Chemical of Concern: QZFPE

Borreani, Giorgio; Chion, Andrea Revello; Colombini, Stefania; Odoardi, Miriam; Paoletti, Renato, and 

Tabacco, Ernesto. Fermentative profiles of field pea (Pisum sativum), faba bean (Vicia faba) 

and white lupin (Lupinus albus) silages as affected by wilting and inoculation. 2009 May 26-; 

151, (3-4): 316-323. 

Notes: Chemical of Concern: QZFPE

Bourgeois, Luc and Morrison, Lan N. Mapping risk areas for resistance to ACCase inhibitor herbicides in 

Manitoba. 1997; 77, (1): 173-179. 

Notes: Chemical of Concern: QZFPE

Butz, S. and Stan, H.-J. Screening of 265 Pesticides in Water by Thin-Layer Chromatography with Automated 

Multiple Development. 1995; 67, (3): 620-30. 

Notes: Chemical of Concern: QZFPE

Cao, X. H.; Li, S. Y.; Wang, C. L., and Lu, M. F. Potential Use of the Herbicide Quizalofop-P-Ethyl for 

Eicosapentaenoic Acid Overproduction by the Diatom Nitzschia Laevis. 2007; 23, (5): 885-

890(CHI) (ENG ABS). 139414.

Notes: Chemical of Concern: QZFPE

Chen, Guoqiang; Cao, Pengying, and Liu, Renjiang. A multi-residue method for fast determination of pesticides 

in tea by ultra performance liquid chromatography electrospray tandem mass spectrometry 

combined with modified QuEChERS sample preparation procedure. 2011 Apr 15-; 125, (4): 

1406-1411. 

Notes: Chemical of Concern: QZFPE

Chu, Xiao-Gang; Hu, Xiao-Zhong, and Yao, Hui-Yuan. Determination of 266 pesticide residues in apple juice 

by matrix solid-phase dispersion and gas chromatography-mass selective detection. 2005; 
156

1063, (1-2): 201-210. 

Notes: Chemical of Concern: QZFPE

Colbach, N.; Kurstjens, D. A. G.; Munier-Jolain, N. M.; Dalbies, A., and Dore, T. Assessing Non-Chemical 

Weeding Strategies Through Mechanistic Modelling of Blackgrass (Alopecurus myosuroides 

Huds.) Dynamics. SOIL; 2010; 32, (3): 205-218. 

Notes: Chemical of Concern: CMZ,CPR,FXP,MCPA,NPP,QZFE,TFN

Curini, R.; Gentili, A.; Marchese, S.; Marino, A., and Perret, D. Solid-phase extraction followed by highperformance liquid chromatography-ionspray interface-mass spectrometry for monitoring of 

herbicides in environmental water. 2000; 874, (2): 187-198. 

Notes: Chemical of Concern: QZFPE

D'Ascenzo, Giuseppe; Gentili, Alessandra; Marchese, Stefano, and Perret, Daniela. Determination of 

arylphenoxypropionic herbicides in water by liquid chromatography-electrospray mass 

spectrometry. 1998; 813, (2): 285-297. 

Notes: Chemical of Concern: QZFPE

de Julian-Ortiz, J. V.; Garcia-Domenech, R.; Galvez, J., and Pogliani, L. Predictability and prediction of lowest 

observed adverse effect levels in a structurally heterogeneous set of chemicals. 2005; 16, (3): 

263-272. 

Notes: Chemical of Concern: QZFPE

Dogan, Ergun; Kirnak, Halil, and Copur, Osman. Deficit irrigations during soybean reproductive stages and 

CROPGRO-soybean simulations under semi-arid climatic conditions. 2007 Aug 30-; 103, (2): 

154-159. 

Notes: Chemical of Concern: QZFPE

Elefsiniotis, I. S.; Liatsos, G. D.; Stamelakis, D., and Moulakakis, A. Case Report: Mixed 

Cholestatic/Hepatocellular Liver Injury Induced by the Herbicide Quizalofop-P-Ethyl. 2007; 

115, 1479-1481. 143010.

Notes: Chemical of Concern: QZFPE

European Commission DG Environment. Endocrine Disrupters: Study on Gathering Information on 435 

Substances with Insufficient Data. 2002: 279 p. 

Notes: EcoReference No.: 110504

Chemical of Concern: 

24DB,ABM,ADC,AMZ,AZD,Al,BAP,BFT,BMC,BMN,BMY,BTN,CBF,CBL,CPY,CPZ,CT

Z,CZE,Cd,Cu,DDT,DDVP,DFC,DFZ,DM,DMBA,DMT,ECZ,EDB,EFV,EFX,ETU,FGSNH,

FML,FNB,FNT,FPN,FRM,FRN,FTF,FVL,FYC,FZFB,GFS,GYP,Hg,ILL,IODN,LCYT,MBZ

,MEM,MLT,MOM,MVP,MXC,MYC,MZB,NATL,Nabam,OXD,OXN,OYZ,PAH,PCL,PCP,

PCZ,PDM,PHTH,PL,PMR,PMT,PPB,PPCP,PPHD,PYN,Pb,QZFE,RSM,SMT,TCF,TDM,TE

Z,TFN,TPZ,TVP,TZA

Fratev, F.; Lo Piparo, E.; Benfenati, E., and Mihaylova, E. Toxicity study of allelochemical-like pesticides by a 

combination of 3D-QSAR, docking, Local Binding Energy (LBE) and GRID approaches. 

2007; 18, (7&8): 675-692. 

Notes: Chemical of Concern: QZFPE

Garcia-Domenech, R.; Julian-Ortiz, J. V., and Besalu, E. True prediction of lowest observed adverse effect 

levels. 2006; 10, (2): 159-168. 

Notes: Chemical of Concern: QZFPE

Gebhardt, W.; Genin, E.; Ghosh, D.; Churchill, M.; Klein, J., and Alder, L. Detection of 88 pesticides on the 

Finnigan TSQ quantum discovery using a novel LC-MS/MS method. Water Contamination 
157

Emergencies. 2006: 324-327. 

Notes: Chemical of Concern: QZFPE

Gelsomino, Antonio; Petrovicova, Beatrix; Tiburtini, Simona; Magnani, Ermenegildo, and Felici, Marcello. 

Multiresidue analysis of pesticides in fruits and vegetables by gel permeation chromatography 

followed by gas chromatography with electron-capture and mass spectrometric detection. 

1997; 782, (1): 105-122. 

Notes: Chemical of Concern: QZFPE

Gupta, P.K. Chapter 39 - Herbicides and fungicides. Ramesh C. Gupta. San Diego: Academic Press; 2011: 503-

521. 

Notes: Chemical of Concern: QZFPE

Hajslova, J.; Pudil, F.; Jehlickova, Z.; Viden, I., and Davidek, J. Gas chromatographic-mass spectrometric 

investigation of phenoxypropanoic acid derivatives possessing herbicidal activity. 1988; 438, 

(1): 55-60. 

Notes: Chemical of Concern: QZFPE

Hatzios, K. K . Cases and mechanisms of resistance to ACCase-inhibiting herbicides. 2002; 808, (Agrochemical 

Resistance): 135-149. 

Notes: Chemical of Concern: QZFPE

Hernandez, F. ; Pozo, O. J.; Sancho, J. V.; Bijlsma, L.; Barreda, M., and Pitarch, E. Multiresidue liquid 

chromatography tandem mass spectrometry determination of 52 non gas chromatographyamenable pesticides and metabolites in different food commodities. 2006; 1109, (2): 242-252. 

Notes: Chemical of Concern: QZFPE

Hiroyuki, Kawahigashi. Transgenic plants for phytoremediation of herbicides: Food biotechnology / Plant 

biotechnology. 2009 Apr; 20, (2): 225-230. 

Notes: Chemical of Concern: QZFPE

Hu, Jian-Ying ; Aizawa, Takako, and Magara, Yasumoto. Analysis of pesticides in water with liquid 

chromatography/atmospheric pressure chemical ionization mass spectrometry. 1998; 33, (2): 

417-425. 

Notes: Chemical of Concern: QZFPE

Hu, Xiaozhong ; Yu, Jianxin; Yan, Zhigang; Ni, Lansun; Lin, Yanfei; Wang, Peng; Jing, Li; Xin, Huang; Chu, 

Xiaogang, and Zhang, Yibin. Determination of multiclass pesticide residues in apple juice by 

gas chromatography-mass selective detection after extraction by matrix solid-phase 

dispersion. 2004; 87, (4): 972-985. 

Notes: Chemical of Concern: QZFPE

Huijbregts, Mark A. J.; Rombouts, Linda J. A.; Ragas, Ad M. J., and van de Meent, Dik. Human toxicological 

effect and damage factors of carcinogenic and noncarcinogenic chemicals for life cycle 

impact assessment. 2005; 1, (3): 181-244. 

Notes: Chemical of Concern: QZFPE

Hull, M. R. and Cobb, A. H. The effect of graminicides on plant plasma membrane H+-ATPase activity in vitro. 

1997(Vol. 2): 819-824. 

Notes: Chemical of Concern: QZFPE

Hull, M. R. and Cobb, A. H. An Investigation of Herbicide Interaction with the H+-ATPase Activity of Plant 

Plasma Membranes. SOIL; 1998; 53, (2): 155-164. 

Notes: Chemical of Concern: 

24D,24DXY,ACR,BT,CPR,CSF,DFPM,DPPI,EPTC,FNPE,FXP,HFPM,IZT,MCPA,MCPPI,
158

MTSM,PHMD,QZFE,SXD,TFN,TRL

Huuskonen, Jarmo. Prediction of Soil Sorption Coefficient of a Diverse Set of Organic Chemicals From 

Molecular Structure. 2003; 43, (5): 1457-1462. 

Notes: Chemical of Concern: QZFPE

Huwe, Janice K.; Clark, George C.; Chu, Andrew C., and Garry, Vincent. CALUX and high resolution GC/MS 

analysis of dioxin-like compounds in chlorophenoxy pesticide formulations . 2003; 60, 227-

230. 

Notes: Chemical of Concern: QZFPE

Inui, Hideyuki; Shiota, Noriaki; Motoi, Yukiko; Ido, Yoshiko; Inoue, Tomomi; Kodama, Takuya; Ohkawa, 

Yasunobu, and Ohkawa, Hideo. Metabolism of herbicides and other chemicals in human 

cytochrome P450 species and in transgenic potato plants co-expressing human CYP1A1, 

CYP2B6 and CYP2C19. 2001; 26, (1): 28-40. 

Notes: Chemical of Concern: QZFPE

Itoh, T. TARGA, a New Post Emergence Grass Killer. SOIL; 1986; 48, 13-15. 

Notes: EcoReference No.: 31261

Chemical of Concern: QZFE

Jehlickova, Zuzana; Hajslova, Jana; Poustka, Jan; Pudil, Frantisek, and Davidek, Jiri. Determination of 

aryloxyphenoxypropanoic acid derivatives in crops treated with herbicidal sprays. 1990; 190, 

(5): 436-40. 

Notes: Chemical of Concern: QZFPE

Jiang, Xiao-Xue; Shi, Hai-Yan; Wu, Ni, and Wang, Ming-Hua. Development of an enzyme-linked 

immunosorbent assay for diniconazole in agricultural samples. 2011 Apr 15-; 125, (4): 1385-

1389. 

Notes: Chemical of Concern: QZFPE

Kamrin, M. A. Pesticide Profiles Toxicity Environmental Impact and Fate. 1997; London, england, uk. Isbn 1-

56670-190-2.; 0, (0): Xix+676p. 

Notes: Chemical of Concern: QZFPE

Kawahigashi, H.; Hirose, S.; Ohkawa, H., and Ohkawa, Y. Herbicide Resistance of Transgenic Rice Plants 

Expressing Human CYP1A1. SOIL; 2007; 25, (1): 75-84. 

Notes: Chemical of Concern: ATZ,CPP,DU,NFZ,PDM,QZFE,SZ

Khalaf, Ali; Gr+_e, Danielle; Abdallah, Hassan; Jaber, Nada ; Hachem, Ali, and Gr+_e, Ren+. A new flexible 

strategy for the synthesis of gem-difluoro-bisarylic derivatives and heterocyclic analogues. 

2011 May 27-; 67, (21): 3881-3886. 

Notes: Chemical of Concern: QZFPE

Klein, Jeannette and Alder, Lutz. Applicability of gradient liquid chromatography with tandem mass 

spectrometry to the simultaneous screening for about 100 pesticides in crops. 2003; 86, (5): 

1015-1037. 

Notes: Chemical of Concern: QZFPE

Knudsen, Thomas B.; Houck, Keith A.; Sipes, Nisha S.; Singh, Amar V.; Judson, Richard S.; Martin, Matthew 

T.; Weissman, Arthur; Kleinstreuer, Nicole C.; Mortensen, Holly M.; Reif, David M.; 

Rabinowitz, James R.; Setzer, R. Woodrow; Richard, Ann M.; Dix, David J., and Kavlock, 

Robert J. Activity profiles of 309 ToxCast äó chemicals evaluated across 292 biochemical 

targets. 2011 Mar 28-; 282, (1-2): 1-15. 

Notes: Chemical of Concern: QZFPE
159

Lewosz, W. The Influence of Some Post-Emergence Herbicides on the Incidence of Blackleg and Soft Rot in 

the Potato. 1989(1): 241-242. 152172.

Notes: Chemical of Concern: QZFPE

Liao, Wenta; Joe, Ton, and Cusick, William G. Multiresidue screening method for fresh fruits and vegetables 

with gas chromatographic/mass spectrometric detection. 1991; 74, (3): 554-65. 

Notes: Chemical of Concern: QZFPE

Liman, Recep; Aky-_l, Dilek; Eren, Yasin, and Konuk, Muhsin . Testing of the mutagenicity and genotoxicity 

of metolcarb by using both Ames/Salmonella and Allium test. 2010 Aug; 80, (9): 1056-1061. 

Notes: Chemical of Concern: QZFPE

Linden, Rafael; Feltraco, Lilian L.; Comerlato, Luana Christine; Kellermann, Estef+ónio, and Antunes, Marina 

V. Computer assisted substance identification in systematic toxicological analysis: New life 

for old methods? 2010 Oct 10-; 202, (1-3): e53-e60. 

Notes: Chemical of Concern: QZFPE

Liu, Zhen-Jiang; Yu, Peng-Min; Fang, Song; Fan, Jia-qin, and Wang, Ming-Hua. Development of an enzymelinked immunosorbent assay for determination of pretilachlor in water and soil. 2011 Sep; 74, 

(6): 1595-1599. 

Notes: Chemical of Concern: QZFPE

Louie, Theola ; Goodman, C. Dean; Holloway, Georgina A.; McFadden, Geoffrey I.; Mollard, Vanessa, and 

Watson, Keith G. Dimeric cyclohexane-1,3-dione oximes inhibit wheat acetyl-CoA 

carboxylase and show anti-malarial activity. 2010 Aug 1-; 20, (15): 4611-4613. 

Notes: Chemical of Concern: QZFPE

Lupwayi, N. Z.; Hanson, K. G.; Harker, K. N.; Clayton, G. W.; Blackshaw, R. E.; O ÇÖDonovan, J. T.; 

Johnson, E. N.; Gan, Y.; Irvine, R. B., and Monreal, M. A. Soil microbial biomass, functional 

diversity and enzyme activity in glyphosate-resistant wheat canola rotations under lowdisturbance direct seeding and conventional tillage. 2007 Jul; 39, (7): 1418-1427. 

Notes: Chemical of Concern: QZFPE

Mac+_, Karen; Morlon, Pierre; Munier-Jolain, Nicolas, and Qu+_r+_, Lionel. Time scales as a factor in 

decision-making by French farmers on weed management in annual crops. 2007 Mar; 93, (1-

3): 115-142. 

Notes: Chemical of Concern: QZFPE

Makino, Kenzi ; Sakata, Gozyo; Kuramoto, Junji, and Nakayama, Mitsuru. Crystal structure of a new herbicide, 

ethyl 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propanoate. 1986; 11, (2): 237-43. 

Notes: Chemical of Concern: QZFPE

Marchese, Stefano; Perret, Daniela; Gentili, Alessandra; Curini, Roberta, and Marino, Aldo. Development of a 

method based on accelerated solvent extraction and liquid chromatography/mass spectrometry 

for determination of arylphenoxypropionic herbicides in soil. 2001; 15, (6): 393-400. 

Notes: Chemical of Concern: QZFPE

Martens, D. A. and Bremner, J. M. Effects of preemergence and postemergence herbicides on urea hydrolysis 

and nitrification of urea nitrogen in soil. 1994; 17, (4): 309-13. 

Notes: Chemical of Concern: QZFPE

McDuffie, Helen H.; Pahwa, Punam; Robson, Diane; Dosman, James A.; Fincham, Shirley; Spinelli, John J., 

and McLaughlin, John R. Insect Repellents, Phenoxyherbicide Exposure, and Non-Hodgkin's 

Lymphoma. 2005; 47, (8): 806-816. 

Notes: Chemical of Concern: QZFPE
160

Menard, C+ line; Heraud, Fanny; Nougadere, Alexandre; Volatier, Jean-Luc, and Leblanc, Jean-Charles. 

Relevance of integrating agricultural practices in pesticide dietary intake indicator. 2008 Oct; 

46, (10): 3240-3253. 

Notes: Chemical of Concern: QZFPE

Miyake, K.; Araki, O., and Matsumura, M. Crystallization behaviors of a- and b-quizalofop-ethyl polymorphs 

in homogeneous nucleation. 1997; 667, (Separation and Purification by Crystallization): 101-

110. 

Notes: Chemical of Concern: QZFPE

Montoro, Elena Pastor; Gonzalez, Roberto Romero; Frenich, Antonia Garrido; Torres, M. Elena Hernandez, 

and Vidal, Jose Luis Martinez. Fast determination of herbicides in waters by ultraperformance liquid chromatography/tandem mass spectrometry. 2007; 21, (22): 3585-3592. 

Notes: Chemical of Concern: QZFPE

Mueller, Markus D. and Bosshardt, Hans Paul. Enantiomer resolution and assay of propionic acid-derived 

herbicides in formulations by using chiral liquid chromatography and achiral gas 

chromatography. 1988; 71, (3): 614-17. 

Notes: Chemical of Concern: QZFPE

Mumtaz, M. M. ; Knauf, L. A.; Reisman, D. J.; Peirano, W. B. ; DeRosa, C. T.; Gombar, V. K.; Enslein, K.; 

Carter, J. R.; Blake, B. W., and et al. Assessment of effect levels of chemicals from 

quantitative structure-activity relationship (QSAR) models. I. Chronic lowest-observedadverse-effect level (LOAEL). 1995; 79 , (1-3): 131-43. 

Notes: Chemical of Concern: QZFPE

Nakahira, Kunimitsu. Mode of action of a herbicide, quizalofop-ethyl. 1998; 23, (3): 357-366. 

Notes: Chemical of Concern: QZFPE

Nakahira, Kunimitu; Haga, Megumi; Uchiyama, Masaaki, and Suzuki, Koichi. Action Mechanism of the 

herbicide quizalofop-ethyl. IV. Comparative effects of quizalofop and its esters on acetylCoA carboxylase and fatty acid biosynthesis in corn leaf chloroplasts. 1990; 15, (2): 189-97. 

Notes: Chemical of Concern: QZFPE

Nilsson, Hjalmar. Persistence and mobility of herbicides in arable soils. Investigations during 1984-1985. 1987; 

28th, (1): 207-14. 

Notes: Chemical of Concern: QZFPE

Nougad+żre, Alexandre; Reninger, Jean-C+ dric; Volatier, Jean-Luc, and Leblanc, Jean-Charles. Chronic 

dietary risk characterization for pesticide residues: A ranking and scoring method integrating 

agricultural uses and food contamination data. 2011 Jul; 49, (7 ): 1484-1510. 

Notes: Chemical of Concern: QZFPE

Omote, M.; Harayama, K.; Sasaki, T.; Mochizuki, N., and Yamashita, H. Analysis of simultaneous screening 

for 277 pesticides in malt and beer by liquid chromatography with tandem mass spectrometry. 

2006; 64, (3): 139-150. 

Notes: Chemical of Concern: QZFPE

Ono, Yukiko; Yamagami, Takashi; Nishina, Takeshi, and Tobino, Toshiaki. Pesticide multiresidue analysis of 

303 compounds using supercritical fluid extraction. 2006; 22, (11): 1473-1476. 

Notes: Chemical of Concern: QZFPE

Pang, G.-F.; Fan, C.-L.; Liu, Y.-M.; Cao, Y.-Z.; Zhang, J.-J.; Fu, B.-L.; Li, X.-M.; Li, Z.-Y., and Wu, Y.-P. 

Multi-residue method for the determination of 450 pesticide residues in honey, fruit juice and 

wine by double-cartridge solid-phase extraction/gas chromatography-mass spectrometry and 
161

liquid chromatography-tandem mass spectrometry. 2006; 23, (8): 777-810. 

Notes: Chemical of Concern: QZFPE

Pang, Guo-Fang; Cao, Yan-Zhong; Zhang, Jin-Jie; Fan, Chun-Lin; Liu, Yong-Ming; Li, Xue-Min; Jia, GuangQun; Li, Zeng-Yin; Shi, Yu-Qiu; Wu, Yan-Ping, and Guo, Tong-Tong. Validation study on 

660 pesticide residues in animal tissues by gel permeation chromatography cleanup/gas 

chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. 

2006; 1125, (1): 1-30. 

Notes: Chemical of Concern: QZFPE

Pang, Guo-Fang; Fan, Chun-Lin; Liu, Yong-Ming; Cao, Yan-Zhong; Zhang, Jin-Jie; Li, Xue-Min; Li, ZengYin; Wu, Yan-Ping, and Guo, Tong-Tong. Determination of residues of 446 pesticides in 

fruits and vegetables by three-cartridge solid-phase extraction-gas chromatography-mass 

spectrometry and liquid chromatography-tandem mass spectrometry. 2006; 89, (3): 740-771. 

Notes: Chemical of Concern: QZFPE

Pang, Guo-Fang; Liu, Yong-Ming; Fan, Chun-Lin; Zhang, Jin-Jie; Cao, Yan-Zhong; Li, Xue-Min; Li, ZengYin; Wu, Yan-Ping, and Guo, Tong-Tong. Simultaneous determination of 405 pesticide 

residues in grain by accelerated solvent extraction then gas chromatography-mass 

spectrometry or liquid chromatography-tandem mass spectrometry. 2006; 384, (6): 1366-

1408. 

Notes: Chemical of Concern: QZFPE

Papa, Ester; Castiglioni, Sara; Gramatica, Paola; Nikolayenko, Victor; Kayumov, Odil, and Calamari, Davide. 

Screening the leaching tendency of pesticides applied in the Amu Darya Basin (Uzbekistan). 

2004; 38, (16): 3485-3494. 

Notes: Chemical of Concern: QZFPE

Pesticide tolerance for quizalofop ethyl. 1988; 53, (120): 23391-3. 

Notes: Chemical of Concern: QZFPE

Pesticide tolerance for quizalofop-p ethyl ester. 1992; 57, (112): 24553-4. 

Notes: Chemical of Concern: QZFPE

Quizalofop ethyl; Pesticide tolerance. 2006; 71, (187): 56374-56378. 

Notes: Chemical of Concern: QZFPE

Quizalofop ethyl; tolerance for use on pineapple. 1996; 61, (119): 31041-31042. 

Notes: Chemical of Concern: QZFPE

Quizalofop-p ethyl ester; pesticide tolerance. 1998; 63, (115): 32753-32760. 

Notes: Chemical of Concern: QZFPE

Quizalofop-P ethyl ester; pesticide tolerance and feed additive regulation. 1996; 61, (116): 30171-30175. 

Notes: Chemical of Concern: QZFPE

Rao, A. N.; Johnson, D. E.; Sivaprasad, B.; Ladha, J. K., and Mortimer, A. M. Weed Management in 

Direct Seeded Rice. Donald L. SparksVolume 93 ed. Academic Press; 2007: 153-255. 

Notes: Chemical of Concern: QZFPE

Rissato, Sandra R.; Galhiane, Mario S.; Apon, Benhard M., and Arruda, Maria S. P. Multiresidue Analysis of 

Pesticides in Soil by Supercritical Fluid Extraction/Gas Chromatography with ElectronCapture Detection and Confirmation by Gas Chromatography-Mass Spectrometry. 2005; 53, 

(1): 62-69. 

Notes: Chemical of Concern: QZFPE
162

Rissato, Sandra Regina; Galhiane, Mario Sergio; de Souza, Antonio G., and Apon, Bernhard M. Development 

of a supercritical fluid extraction method for simultaneous determination of 

organophosphorus, organohalogen, organonitrogen and pyretroids pesticides in fruit and 

vegetables and its comparison with a conventional method by GC-ECD and GC-MS. 2005; 

16, (5): 1038-1047. 

Notes: Chemical of Concern: QZFPE

Rissato, Sandra R.; Galhiane, Mario S.; Knoll, Fatima R. N., and Apon, Bernhard M. Supercritical fluid 

extraction for pesticide multiresidue analysis in honey: determination by gas chromatography 

with electron-capture and mass spectrometry detection. 2004; 1048, (2): 153-159. 

Notes: Chemical of Concern: QZFPE

Roebuck, J. F. and Flint, C. E. A review of agricultural development and advisory service trials for recently 

introduced specific grass weed herbicides for winter oilseed rape and the effect on yield of the 

timing of removal of volunteer cereals. 1983-1985. 1985(1): 199-207. 

Notes: Chemical of Concern: QZFPE

Ruizzo, Michael A. and Gorski, Stanley F. Inhibition of chloroplast-mediated reactions by quizalofop herbicide. 

1988; 36, (6): 713-18. 

Notes: Chemical of Concern: QZFPE

Russom, C. L. ; Bradbury, S. P., and Carlson, A. R. Use of knowledge bases and QSARS to estimate the 

relative ecological risk of agrichemicals: a problem formulation exercise. 1995; 4, (2-3): 83-

95. 

Notes: Chemical of Concern: QZFPE

Sanchez-Bayo, Francisco. Comparative acute toxicity of organic pollutants and reference values for 

crustaceans. I. Branchiopoda, Copepoda and Ostracoda. 2006; 139, (3): 385-420. 

Notes: Chemical of Concern: QZFPE

Sandra, Pat; Tienpont, Bart, and David, Frank. Stir bar sorptive extraction (Twister) RTL-CGC-MS. A versatile 

method to monitor more than 400 pesticides in different matrices (water, beverages, fruits, 

vegetables, baby food). New Horizons and Challenges in Environmental Analysis and 

Monitoring, [Workshop], Gdansk, Poland, Aug. 18-29, 2003 . 2003: 338-354. 

Notes: Chemical of Concern: QZFPE

Santier, S. and Chamel, A. Penetration of Triolein and Methyl Oleate Through Isolated Plant Cuticles and Their 

Effect on Penetration of (14C)Quizalofop-Ethyl and (14C)Fenoxaprop-Ethyl. Lab. Transferts 

dans les Systemes Veg., CEArenoble, DBMS, 17 rue des Martyrs, 38054 Grenoble Cedex 9, 

France////: SOIL; 1996; 36, (2): 167-174. 

Notes: Chemical of Concern: FNP,QZFE

Serafimova, R.; Walker, J., and Mekenyan, O. Androgen receptor binding affinity of pesticide \"active\" 

formulation ingredients. QSAR evaluation by COREPA method. 2002; 13 , (1): 127-134. 

Notes: Chemical of Concern: QZFPE

Serre, I.; Cabanne, F., and Gauvrit, C. Behavior of alkyl oleates on leaf surfaces in relation to their influence on 

herbicide penetration. 1996(Vol. 3): 807-812. 

Notes: Chemical of Concern: QZFPE

Shiroishi, Akihiro; Hashiba, Isao; Kokubo, Ryo; Miyake, Kazuo, and Kawamura, Yuji. Semi-batch cooling 

crystallization of quizalofop-ethyl with polymorphism. 1990; 438, (Cryst. Sep. Process): 261-

70. 

Notes: Chemical of Concern: QZFPE
163

Simon, S.; Defrance, H., and Sauphanor, B. Effect of Codling Moth Management on Orchard Arthropods. 2007; 

122, (3): 340-348. 

Notes: Chemical of Concern: 

24D,24DXY,ACP,ALSV,AMTL,AZ,CPY,CYF,Captan,Cu,DMT,DOD,DU,FRM,GFSNH,G

YP,HCZ,IMC,MOIL,MP,MZB,OXD,PHSL,PRB,QZFE,RTN,SFR,SZ,TDF,THM,TPM

Stan, Hans-Jurgen. Pesticide residue analysis in foodstuffs applying capillary gas chromatography with mass 

spectrometric detection. State-of-the-art use of modified DFG-multi-method S19 and 

automated data evaluation. 2000; 892, (1+2): 347-377. 

Notes: Chemical of Concern: QZFPE

Stan, Hans-Juergen and Linkerhaegner, Manfred. Pesticide residue analysis in foodstuffs applying capillary gas 

chromatography with atomic emission detection. State-of-the-art use of modified multimethod 

S19 of the Deutsche Forschungsgemeinschaft and automated large-volume injection with 

programmed-temperature vaporization and solvent venting. 1996; 750, (1+2, 4th International 

Symposium on Hyphenated Techniques in Chromatography and Hyphenated 

Chromatographic Analyzers, 1996): 369-390. 

Notes: Chemical of Concern: QZFPE

Tao, Shu; Piao, Haishan; Dawson, R.; Lu, Xiaoxia, and Hu, Haiying. Estimation of Organic Carbon Normalized 

Sorption Coefficient (KOC) for Soils Using the Fragment Constant Method. 1999; 33, (16): 

2719-2725. 

Notes: Chemical of Concern: QZFPE

Tetsuo, Satoh. Chapter 8 - Global Epidemiology of Organophosphate and Carbamate Poisonings. Ramesh C. 

Gupta. Burlington: Academic Press; 2006: 89-100. 

Notes: Chemical of Concern: QZFPE

Tian, Qin; Lv, Chunguang; Wang, Peng; Ren, Liping; Qiu, Jing; Li, Li, and Zhou, Zhiqiang. Enantiomeric 

separation of chiral pesticides by high performance liquid chromatography on cellulose tris3,5-dimethyl carbamate stationary phase under reversed phase conditions. 2007; 30, (3): 310-

321. 

Notes: Chemical of Concern: QZFPE

Tice, Colin M . Selecting the right compounds for screening: use of surface-area parameters. 2002; 58, (3): 219-

233. 

Notes: Chemical of Concern: QZFPE

Tolerances for quizalofop ethyl. 1988; 53, (120): 23386-7. 

Notes: Chemical of Concern: QZFPE

Undevia, Samir D.; Innocenti, Federico; Ramirez, Jacqueline; House, Larry; Desai, Apurva A.; Skoog, Linda 

A.; Singh, Deepti A.; Karrison, Theodore; Kindler, Hedy L., and Ratain, Mark J. A phase I 

and pharmacokinetic study of the quinoxaline antitumour Agent R(+)XK469 in patients with 

advanced solid tumours. 2008 Aug; 44, (12): 1684-1692. 

Notes: Chemical of Concern: QZFPE

Vilar, Santiago; Quezada, Elias; Alcaide, Carlos; Orallo, Francisco; Santana, Lourdes, and Uriarte, Eugenio. 

Quantitative structure vasodilatory activity relationship - synthesis and \"in silico\" and \"in 

vitro\" evaluation of resveratrol-coumarin hybrids. 2007; 26, (3): 317-332. 

Notes: Chemical of Concern: QZFPE

Volante, Marco; Pontello, Mirella; Valoti, Laura; Cattaneo, Manuela; Bianchi, Mascia, and Colzani, Luisa. 

Application of solid phase micro-extraction (SPME) to the analysis of pesticide residues in 

vegetables. 2000; 56, (7): 618-636. 
164

Notes: Chemical of Concern: QZFPE

Wang, C. J. and Liu, Z. Q. Foliar uptake of pesticides ÇöPresent status and future challenge. 2007 Jan; 87, (1): 

1-8. 

Notes: Chemical of Concern: QZFPE

Wang, Jian-Hua; Zhang, Yi-Bing, and Wang, Xiu-Lin. Determination of multiclass pesticide residues in apple 

juice by gas chromatography-mass spectrometry with large-volume injection. 2006; 29, (15): 

2330-2337. 

Notes: Chemical of Concern: QZFPE

Wang, Jun-Dong; Bao, Hua-Jun; Shi, Hai-Yan, and Wang, Ming-Hua. Development of an enzyme-linked 

immunosorbent assay for quantitative determination of cyhalofop-butyl. 2010 Sep; 98, (1): 

68-72. 

Notes: Chemical of Concern: QZFPE

Wang, Peng; Jiang, Shuren; Liu, Donghui; Shan, Weili; Zhang, Hongjun, and Zhou, Zhiqiang. Chiral 

separations of pesticide enantiomers by high-performance liquid chromatography using 

cellulose triphenylcarbamate chiral stationary phase. 2006; 44, (10): 602-606. 

Notes: Chemical of Concern: QZFPE

Wang, Peng; Liu, Donghui; Jiang, Shuren; Xu, Yangguang; Gu, Xu, and Zhou, Zhiqiang. The chiral resolution 

of pesticides on amylose-tris(3,5-dimethylphenylcarbamate) CSP by HPLC and the 

enantiomeric identification by circular dichroism. 2008; 20, (1): 40-46. 

Notes: Chemical of Concern: QZFPE

Y-_ld-_z, Mustafa; Ci- erci, brahim Hakk; Konuk, Muhsin ; Fatih Fidan, A., and Terzi, Hakan. Determination 

of genotoxic effects of copper sulphate and cobalt chloride in Allium cepa root cells by 

chromosome aberration and comet assays. 2009 May; 75, (7): 934-938. 

Notes: Chemical of Concern: QZFPE

Zeng, Deyi; Shi, Haiyan; Li, Bo; Wang, Minghua, and Song, Baoan. Development of an Enzyme-Linked 

Immunosorbent Assay for Quantitative Determination of Quizalofop-p-ethyl. 2006; 54, (23): 

8682-8687. 

Notes: Chemical of Concern: QZFPE

Zuther, E.; Johnson, J. J.; Haselkorn, R.; McLeod, R., and Gornicki, P. Growth of Toxoplasma gondii is 

inhibited by aryloxyphenoxypropionate herbicides targeting acetyl-CoA carboxylase. 1999; 

96, (23): 13387-13392. 

Notes: Chemical of Concern: QZFPE
165

Appendix E – SIP and STIR Model Output

STIR

Input

Application and Chemical Information

Enter Chemical Name

Quizalofop-pethyl

Enter Chemical Use

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) ground

Enter Chemical Molecular Weight (g/mole) 372.8

Enter Chemical Vapor Pressure (mmHg) 3.00E-07

Enter Application Rate (lb a.i./acre) 0.667

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2000

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 870

Enter Lowest Rat Inhalation LC50 (mg/L) 5119

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 6.02E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 7.57E-04

Adjusted Inhalation LD50 4.73E+04

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.60E-08 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 7.05E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 1.49E-06 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 6.02E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 9.51E-04

Adjusted Inhalation LD50 3.05E+05

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.12E-09 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 8.86E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 2.91E-07 Exposure not Likely Significant
166

LD50

SIP

Table 1. Inputs

Parameter Value

Chemical name Quizalofop-p-ethyl

Solubility (in water at 25oC; mg/L) 0.4

Mammalian LD50 (mg/kg-bw) 870

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 5

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Avian LD50 (mg/kg-bw) 2000

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 180

Bobwhite quail NOAEC (mg/kg-diet) 1030

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird 

species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.0688 0.0688

Adjusted toxicity value (mg/kg-bw) 669.1697 3.8458

Ratio of exposure to toxicity 0.0001 0.0179

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.3240 0.3240

Adjusted toxicity value (mg/kg-bw) 1038.4508 8.9303
167

Ratio of exposure to acute toxicity 0.0003 0.0363

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. 

Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through 

drinking water may contribute to a total exposure that has potential for effects to non-target animals.
168

Appendix F – Risk Quotient Method and Levels of Concern

The Risk Quotient Method is the means by which the Environmental Fate and Effects 

Division (EFED) integrates the results of exposure and ecotoxicity data. In this method, both 

acute and chronic risk quotients are calculated by dividing exposure estimates by the most 

sensitive ecotoxicity values derived from the studies. Calculated risk quotients are then 

compared to OPP's levels of concern. The levels of concern are the criteria used by OPP to 

indicate potential risk to non-target organisms and the need to consider regulatory action. 

EFED has defined levels of concern for acute risk, potential restricted use, and for listed 

species. Risk presumptions, along with the corresponding risk quotients and levels of concern 

are summarized in the table below.

Levels of Concern for Assessed Taxa

Risk Presumption Risk Quotient Level of 

Concern

Birds

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 

50 mg/kg)

0.2

Acute Listed Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Mammals

Acute Risk EEC/LC50 or LD50/sqft or LD50/day 0.5

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 

50 mg/kg)

0.2

Acute Listed Species EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOAEC 1

Aquatic Animals

Acute Risk EEC/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Listed Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOAEC 1

Terrestrial and Semi-Aquatic Plants 

Acute Risk EEC/EC25 1

Acute Listed Species EEC/EC05 or NOAEC 1
169

Risk Presumption Risk Quotient Level of 

Concern

Aquatic Plants

Acute Risk EEC/EC50 1

Acute Listed Species EEC/EC05 or NOAEC 1
170

Appendix G – Surface Water Model Results and Sample Input and 

Outputs

This expample output (inputs included at end of output) is for the first scenario presented in 

Table 5, the aerial alfalfa scenario (MN alfalfa OP; 2 applications at 0.0834 lb ai/A with a 7-

day re-application interval).

stored as Quiz.out

Chemical: Quizalofop

PRZM environment: MNalfalfaOP.txt modified Thuday, 14 June 2007 at 11:21:44

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:08

Metfile: w14914.dvf modified Tueday, 26 August 2008 at 06:15:16

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day60 Day90 DayYearly

1961 0.6225 0.6176 0.6011 0.5749 0.5616 0.297

1962 1.816 1.798 1.744 1.72 1.692 1.145

1963 1.978 1.965 1.927 1.833 1.818 1.578

1964 2.714 2.694 2.616 2.471 2.419 1.953

1965 2.43 2.421 2.385 2.303 2.267 2.079

1966 2.217 2.206 2.165 2.079 2.048 1.916

1967 2.08 2.07 2.037 1.967 1.919 1.737

1968 1.853 1.843 1.808 1.743 1.7 1.528

1969 2.361 2.346 2.283 2.185 2.119 1.733

1970 2.316 2.303 2.264 2.214 2.16 1.994

1971 2.657 2.642 2.587 2.479 2.407 2.17

1972 2.417 2.406 2.358 2.267 2.231 2.077

1973 2.137 2.128 2.086 2.001 1.96 1.857

1974 2.65 2.633 2.565 2.446 2.399 2.032

1975 3.615 3.597 3.496 3.303 3.197 2.588

1976 2.884 2.871 2.816 2.712 2.649 2.46

1977 3.295 3.272 3.185 3.029 2.946 2.539

1978 3.201 3.183 3.112 3.001 2.948 2.665

1979 2.835 2.822 2.772 2.716 2.715 2.553

1980 2.694 2.681 2.629 2.544 2.481 2.407

1981 3.243 3.223 3.142 3.001 2.924 2.448

1982 2.569 2.558 2.513 2.445 2.407 2.314

1983 2.614 2.6 2.557 2.502 2.498 2.336

1984 3.198 3.177 3.096 2.943 2.845 2.473

1985 3.244 3.226 3.161 3.06 3.019 2.681
171

1986 2.969 2.954 2.899 2.825 2.789 2.587

1987 2.908 2.892 2.838 2.722 2.691 2.451

1988 2.452 2.438 2.383 2.287 2.221 2.163

1989 2.483 2.47 2.422 2.325 2.265 2.144

1990 2.625 2.611 2.553 2.496 2.436 2.156

Sorted results

Prob. Peak 96 hr 21 Day60 Day90 DayYearly

0.032258064516129 3.615 3.597 3.496 3.303 3.197 2.681

0.0645161290322581 3.295 3.272 3.185 3.06 3.019 2.665

0.0967741935483871 3.244 3.226 3.161 3.029 2.948 2.588

0.129032258064516 3.243 3.223 3.142 3.001 2.946 2.587

0.161290322580645 3.201 3.183 3.112 3.001 2.924 2.553

0.193548387096774 3.198 3.177 3.096 2.943 2.845 2.539

0.225806451612903 2.969 2.954 2.899 2.825 2.789 2.473

0.258064516129032 2.908 2.892 2.838 2.722 2.715 2.46

0.290322580645161 2.884 2.871 2.816 2.716 2.691 2.451

0.32258064516129 2.835 2.822 2.772 2.712 2.649 2.448

0.354838709677419 2.714 2.694 2.629 2.544 2.498 2.407

0.387096774193548 2.694 2.681 2.616 2.502 2.481 2.336

0.419354838709677 2.657 2.642 2.587 2.496 2.436 2.314

0.451612903225806 2.65 2.633 2.565 2.479 2.419 2.17

0.483870967741936 2.625 2.611 2.557 2.471 2.407 2.163

0.516129032258065 2.614 2.6 2.553 2.446 2.407 2.156

0.548387096774194 2.569 2.558 2.513 2.445 2.399 2.144

0.580645161290323 2.483 2.47 2.422 2.325 2.267 2.079

0.612903225806452 2.452 2.438 2.385 2.303 2.265 2.077

0.645161290322581 2.43 2.421 2.383 2.287 2.231 2.032

0.67741935483871 2.417 2.406 2.358 2.267 2.221 1.994

0.709677419354839 2.361 2.346 2.283 2.214 2.16 1.953

0.741935483870968 2.316 2.303 2.264 2.185 2.119 1.916

0.774193548387097 2.217 2.206 2.165 2.079 2.048 1.857

0.806451612903226 2.137 2.128 2.086 2.001 1.96 1.737

0.838709677419355 2.08 2.07 2.037 1.967 1.919 1.733

0.870967741935484 1.978 1.965 1.927 1.833 1.818 1.578

0.903225806451613 1.853 1.843 1.808 1.743 1.7 1.528

0.935483870967742 1.816 1.798 1.744 1.72 1.692 1.145

0.967741935483871 0.6225 0.6176 0.6011 0.5749 0.5616 0.297

0.1 3.2439 3.2257 3.1591 3.0262 2.9478 2.5879
172

Average of yearly averages: 2.10203333333333

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: Quiz

Metfile: w14914.dvf

PRZM scenario: MNalfalfaOP.txt

EXAMS environment file: pond298.exv

Chemical Name: Quizalofop

Description Variable Name Value Units Comments

Molecular weight mwt 344.8 g/mol

Henry's Law Const. henry atm-m^3/mol

Vapor Pressure vapr 3e-7 torr

Solubility sol 0.4 mg/L

Kd Kd mg/L

Koc Koc 256 mg/L

Photolysis half-life kdp 85.4 days Half-life

Aerobic Aquatic Metabolism kbacw 814 days Halfife

Anaerobic Aquatic Metabolism kbacs 420 days Halfife

Aerobic Soil Metabolism asm 390 days Halfife

Hydrolysis: pH 7 0 days Half-life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI cm

Application Rate: TAPP .093 kg/ha

Application Efficiency: APPEFF .95 fraction

Spray Drift DRFT .05 fraction of application rate applied to pond

Application Date Date 15-05 dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 1 interval 7 days Set to 0 or delete line for single app.

app. rate 1 apprate kg/ha

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run) 
173

Appendix H – TerrPlant Output

Example output for a single application of quizalofop-p-ethyl at 0.108 lb ai/A (paved 

areas, private roadways)

Table 1. Chemical Identity.

Parameter User Inputs

Chemical Name quizalofop-p-ethyl

PC code 128709

Use Herbicide for grasses

Application Method Spray

Application Form Liquid 

Solubility in Water 

(ppm) 0.4

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol

Value (user 

inputs) Units

Application Rate A 0.108

Incorporation I 1 none

Runoff Fraction R 0.01 none

Drift Fraction D 0.05 none

Table 3. EECs for quizalofop-p-ethyl. Units in .

Description Equation EEC

Runoff to dry areas (A/I)*R 0.00108

Runoff to semi-aquatic areas (A/I)*R*10 0.0108

Spray drift A*D 0.0054

Total for dry areas ((A/I)*R)+(A*D) 0.00648

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.0162

Table 4. Plant survival and growth data used for RQ derivation. Units are in . All values are user 

inputs

Seedling Emergence Vegetative Vigor

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 0.019 0.0096 0.00146 0.000791

Dicot 0.127 0.0931 0.0477

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to quizalofop-p-ethyl through 

runoff and/or spray drift.*

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed 0.34 0.85 3.70

Monocot listed 0.68 1.69 6.83

Dicot non-listed #DIV/0! #DIV/0! <0.1
174

Dicot listed <0.1 0.13 <0.1

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.
175

Appendix I – T-REX Output

Example output from application of quizalofop-p-ethyl at 0.0695 lb ai/A, 2 applications, 

7 days apart

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs

Table X. Upper Bound Kenaga, Acute Avian Dose-Based Risk Quotients

Size 

Class

(grams)

Adjuste

d

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants

Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 0.00 35.53

#DI

V/0! 16.29

#DI

V/0! 19.99 ##### 2.22

#DIV

/0! 13.92

####

# 0.49

###

##

100 0.00 20.26

#DI

V/0! 9.29

#DI

V/0! 11.40 ##### 1.27

#DIV

/0! 7.94

####

# 0.28

###

##

1000 0.00 9.07

#DI

V/0! 4.16

#DI

V/0! 5.10 ##### 0.57

#DIV

/0! 3.55

####

# 0.13

###

##

Table X. Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0 31.20 #DIV/0! 14.30 #DIV/0! 17.55 #DIV/0! 1.95 ##### 12.22 #DIV/0!

Size class not used for dietary risk quotients 

Table X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

NOAEC 

(ppm)

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ
176

180 31.20 0.17 14.30 0.08 17.55 0.10 1.95 0.01 12.22 0.07

Table X. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients 

Size 

Class

(grams)

Adjusted

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants

Fruits/Pods

/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 1912.11 29.75 0.02 13.63 0.01 16.73 0.01 1.86 0.00 11.6511 0.0061 0.4132 0.0002

35 1547.10 20.56 0.01 9.42 0.01 11.56 0.01 1.28 0.00 8.05249 0.0052 0.2855 0.0002

1000 669.17 4.77 0.01 2.18 0.00 2.68 0.00 0.30 0.00 1.867 0.0028 0.0662 1E-04

Table X. Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients

LC50 

(ppm)

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0

31.2

0

#DIV/0

!

14.3

0

#DIV/0

!

17.5

5

#DIV/0

! 1.95 #####

12.2

2

#DIV/0

!

Size class not used for dietary risk quotients

Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC 

(ppm)

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants

Fruits/Pods/Seeds/Lar

ge Insects Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

100

31.2

0 0.31

14.3

0 0.14

17.5

5 0.18 1.95 0.02

12.2

2 0.12

Size class not used for dietary risk quotients 

Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients

Size 

Class

(grams)

Adjusted 

NOAEL

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants

Fruits/Pods

/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 10.99 29.75 2.71 13.63 1.24 16.73 1.52 1.86 0.17 11.65 1.06 0.41 0.04

35 8.89 20.56 2.31 9.42 1.06 11.56 1.30 1.28 0.14 8.05 0.91 0.29 0.03
177

1000 3.85 4.77 1.24 2.18 0.57 2.68 0.70 0.30 0.08 1.87 0.49 0.07 0.02
178

APPENDIX J – Listed Species Analysis

Table J-1. “No Effects” (Direct and Indirect Effects) Determination for Listed Species 

Outside the Geographical Range of Quizalofop-P-Ethyl Uses

Common and Scientific Name

(ncn) Tetraplasandra bisattenuata

(ncn) Tetraplasandra lydgatei

(ncn) Platydesma cornuta var. cornuta

(ncn) Platydesma cornuta var. decurrens

(ncn) Lysimachia vinosa

(ncn) Phyllostegia hispida

(ncn) Schiedea attenuata

(ncn) Stenogyne kealiae

(ncn) Keysseria (=Lagenifera) erici

(ncn) Keysseria (=Lagenifera) helenae

(ncn) Cyanea kolekoleensis

(ncn) Lysimachia iniki

(ncn) Lysimachia pendens

(ncn) Lysimachia scopulensis

(ncn) Phyllostegia renovans

(ncn) Tetraplasandra flynnii

(ncn) Diellia mannii

(ncn) Doryopteris takeuchii

(ncn) Doryopteris angelica

Abalone, Black Haliotis cracherodii

Abalone, White Haliotis sorenseni

Abutilon eremitopetalum (ncn) Abutilon eremitopetalum

Abutilon sandwicense (ncn) Abutilon sandwicense

Achyranthes mutica (ncn) Achyranthes mutica

Achyranthes splendens var. rotundata (ncn) Achyranthes splendens var. rotundata

Adobe Sunburst, San Joaquin Pseudobahia peirsonii

a'e Zanthoxylum oahuense

A'e (Zanthoxylum dipetalum var. tomentosum) Zanthoxylum dipetalum var. tomentosum

A'e (Zanthoxylum hawaiiense) Zanthoxylum hawaiiense

'Aiea (Nothocestrum breviflorum) Nothocestrum breviflorum

'Aiea (Nothocestrum peltatum) Nothocestrum peltatum

Akekee Loxops caeruleirostris

'Akepa, Hawaii Loxops coccineus coccineus

'Akepa, Maui Loxops coccineus ochraceus

'Akia Loa, Kauai (Hemignathus procerus) Hemignathus procerus

'Akia Pola'au (Hemignathus munroi) Hemignathus munroi

Akoko Chamaesyce remyi var. kauaiensis

'akoko Chamaesyce eleanoriae

'Akoko (Chamaesyce celastroides var. kaenana) Chamaesyce celastroides var. kaenana

'Akoko (Chamaesyce deppeana) Chamaesyce deppeana

'Akoko (Chamaesyce herbstii) Chamaesyce herbstii

'Akoko (Chamaesyce kuwaleana) Chamaesyce kuwaleana

'Akoko (Chamaesyce rockii) Chamaesyce rockii

'Akoko (Chamaesyce skottsbergii var. skottsbe Chamaesyce skottsbergii var. kalaeloana

'Akoko (Euphorbia haeleeleana) Euphorbia haeleeleana

Alabama pearlshell Margaritifera marrianae
179

Common and Scientific Name

alani Melicope christophersenii

alani Melicope degeneri

alani Melicope makahae

alani Melicope paniculata

alani Melicope hiiakae

alani Melicope puberula

Alani (Melicope adscendens) Melicope adscendens

Alani (Melicope balloui) Melicope balloui

Alani (Melicope haupuensis) Melicope haupuensis

Alani (Melicope knudsenii) Melicope knudsenii

Alani (Melicope lydgatei) Melicope lydgatei

Alani (Melicope mucronulata) Melicope mucronulata

Alani (Melicope munroi) Melicope munroi

Alani (Melicope ovalis) Melicope ovalis

Alani (Melicope pallida) Melicope pallida

Alani (Melicope quadrangularis) Melicope quadrangularis

Alani (Melicope reflexa) Melicope reflexa

Alani (Melicope saint-johnii) Melicope saint-johnii

Alani (Melicope zahlbruckneri) Melicope zahlbruckneri

Albatross, Short-tailed Phoebastria (=Diomedea) albatrus

Alligator, American Alligator mississippiensis

Allocarya, Calistoga Plagiobothrys strictus

Alsinidendron obovatum (ncn) Alsinidendron obovatum

Alsinidendron trinerve (ncn) Alsinidendron trinerve

Alsinidendron viscosum (ncn) Alsinidendron viscosum

Amaranth, Seabeach Amaranthus pumilus

Amaranthus brownii (ncn) Amaranthus brownii

Ambersnail, Kanab Oxyloma haydeni kanabensis

Ambrosia, San Diego Ambrosia pumila

Ambrosia, South Texas Ambrosia cheiranthifolia

Amphianthus, Little Amphianthus pusillus

Amphipod, Hay's Spring Stygobromus hayi

Amphipod, Illinois Cave Gammarus acherondytes

Amphipod, Noel's Gammarus desperatus

Amphipod, Peck's Cave Stygobromus (=Stygonectes) pecki

'Anaunau (Lepidium arbuscula) Lepidium arbuscula

Anole, Culebra Island Giant Anolis roosevelti

'Anunu (Sicyos alba) Sicyos alba

Asplenium fragile var. insulare (ncn) Asplenium fragile var. insulare

Aster, Decurrent False Boltonia decurrens

Aster, Florida Golden Chrysopsis floridana

Aster, Ruth's Golden Pityopsis ruthii

Auerodendron pauciflorum (ncn) Auerodendron pauciflorum

aumakua, Palapalai Dryopteris crinalis podosorus

Aupaka (Isodendrion hosakae) Isodendrion hosakae

Aupaka (Isodendrion laurifolium) Isodendrion laurifolium

Aupaka (Isodendrion longifolium) Isodendrion longifolium

Avens, Spreading Geum radiatum

awikiwiki Canavalia napaliensis

'Awikiwiki (Canavalia molokaiensis) Canavalia molokaiensis

'Awiwi (Centaurium sebaeoides) Centaurium sebaeoides

'Awiwi (Hedyotis cookiana) Hedyotis cookiana
180

Common and Scientific Name

Ayenia, Texas Ayenia limitaris

Baccharis, Encinitas Baccharis vanessae

Bankclimber, Purple Elliptoideus sloatianus

Barbara Buttons, Mohr's Marshallia mohrii

Barberry, Island Berberis pinnata ssp. insularis

Barberry, Nevin's Berberis nevinii

Bariaco Trichilia triacantha

Bat, Little Mariana Fruit Pteropus tokudae

Bat, Mariana Fruit (=Mariana Flying Fox) Pteropus mariannus mariannus

Bear, American Black Ursus americanus

Bear, polar Ursus maritimus

Bearclaw poppy, Dwarf Arctomecon humilis

Beardtongue, Penland Penstemon penlandii

Bedstraw, El Dorado Galium californicum ssp. sierrae

Bedstraw, Island Galium buxifolium

Beetle, American Burying Nicrophorus americanus

Beetle, Casey's June Dinacoma caseyi

Beetle, Coffin Cave Mold Batrisodes texanus

Beetle, Comal Springs Dryopid Stygoparnus comalensis

Beetle, Comal Springs Riffle Heterelmis comalensis

Beetle, Delta Green Ground Elaphrus viridis

Beetle, Helotes Mold Batrisodes venyivi

Beetle, Hungerford's Crawling Water Brychius hungerfordi

Beetle, Kretschmarr Cave Mold Texamaurops reddelli

Beetle, Mount Hermon June Polyphylla barbata

Beetle, Northeastern Beach Tiger Cicindela dorsalis dorsalis

Beetle, Ohlone Tiger Cicindela ohlone

Beetle, Puritan Tiger Cicindela puritana

Beetle, Salt Creek Tiger Cicindela nevadica lincolniana

Beetle, Tooth Cave Ground Rhadine persephone

Beetle, Valley Elderberry Longhorn Desmocerus californicus dimorphus

Bellflower, Brooksville Campanula robinsiae

Birch, Virginia Round-leaf Betula uber

Bird's-beak, Palmate-bracted Cordylanthus palmatus

Bird's-beak, Pennell's Cordylanthus tenuis ssp. capillaris

Bird's-beak, salt marsh Cordylanthus maritimus ssp. maritimus

Bird's-beak, Soft Cordylanthus mollis ssp. mollis

Birds-in-a-nest, White Macbridea alba

Bittercress, Small-anthered Cardamine micranthera

Blackbird, Yellow-shouldered Agelaius xanthomus

blackline Hawaiian damselfly Megalagrion nigrohamatum nigrolineatum

Bladderpod, Dudley Bluffs Lesquerella congesta

Bladderpod, Kodachrome Lesquerella tumulosa

Bladderpod, Lyrate Lesquerella lyrata

Bladderpod, Missouri Lesquerella filiformis

Bladderpod, San Bernardino Mountains Lesquerella kingii ssp. bernardina

Bladderpod, Spring Creek Lesquerella perforata

Bladderpod, White Lesquerella pallida

Bladderpod, Zapata Lesquerella thamnophila

Blazing Star, Ash Meadows Mentzelia leucophylla

Blazing Star, Heller's Liatris helleri

Blazing Star, Scrub Liatris ohlingerae
181

Common and Scientific Name

Bluecurls, Hidden Lake Trichostema austromontanum ssp. compactum

Blue-star, Kearney's Amsonia kearneyana

Bluet, Roan Mountain Hedyotis purpurea var. montana

Boa, Mona Epicrates monensis monensis

Boa, Puerto Rican Epicrates inornatus

Boa, Virgin Islands Tree Epicrates monensis granti

Bobwhite, Masked Colinus virginianus ridgwayi

Bonamia menziesii (ncn) Bonamia menziesii

Bonamia, Florida Bonamia grandiflora

Boxwood, Vahl's Buxus vahlii

Broom, San Clemente Island Lotus dendroideus ssp. traskiae

Buckwheat, Cushenbury Eriogonum ovalifolium var. vineum

Buckwheat, Ione (incl. Irish Hill) Eriogonum apricum (incl. var. prostratum)

Buckwheat, Scrub Eriogonum longifolium var. gnaphalifolium

Buckwheat, Southern Mountain Wild Eriogonum kennedyi var. austromontanum

Buckwheat, Steamboat Eriogonum ovalifolium var. williamsiae

Bush-mallow, San Clemente Island Malacothamnus clementinus

Bush-mallow, Santa Cruz Island Malacothamnus fasciculatus var. nesioticus

Buttercup, Autumn Ranunculus aestivalis (=acriformis)

Butterfly [Cassius Blue, Ceraunus Blue, Nickerbean 

Blue] Leptotes and Hemiargus and Cyclargus genus

Butterfly Plant, Colorado Gaura neomexicana var. coloradensis

Butterfly, Bay Checkerspot (Wright's euphydryas) Euphydryas editha bayensis

Butterfly, Behren's Silverspot Speyeria zerene behrensii

Butterfly, Callippe Silverspot Speyeria callippe callippe

Butterfly, Ceranus Blue Hemiargus ceraunus antibubastus

Butterfly, El Segundo Blue Euphilotes battoides allyni

Butterfly, Fender's Blue Icaricia icarioides fenderi

Butterfly, Karner Blue Lycaeides melissa samuelis

Butterfly, Lange's Metalmark Apodemia mormo langei

Butterfly, Lotis Blue Lycaeides argyrognomon lotis

Butterfly, Miami Blue Cyclargus thomasi bethunebakeri

Butterfly, Mission Blue Icaricia icarioides missionensis

Butterfly, Mitchell's Satyr Neonympha mitchellii mitchellii

Butterfly, Myrtle's Silverspot Speyeria zerene myrtleae

Butterfly, Nickerbean Blue Cyclargus ammon

Butterfly, Oregon Silverspot Speyeria zerene hippolyta

Butterfly, Palos Verdes Blue Glaucopsyche lygdamus palosverdesensis

Butterfly, Quino Checkerspot Euphydryas editha quino (=E. e. wrighti)

Butterfly, Saint Francis' Satyr Neonympha mitchellii francisci

Butterfly, San Bruno Elfin Callophrys mossii bayensis

Butterfly, Schaus Swallowtail Heraclides aristodemus ponceanus

Butterfly, Smith's Blue Euphilotes enoptes smithi

Butterfly, Uncompahgre Fritillary Boloria acrocnema

Butterweed, Layne's Senecio layneae

Butterwort, Godfrey's Pinguicula ionantha

Button-celery, San Diego Eryngium aristulatum var. parishii

Cactus, Arizona Hedgehog Echinocereus triglochidiatus var. arizonicus

Cactus, Bakersfield Opuntia treleasei

Cactus, Black Lace Echinocereus reichenbachii var. albertii

Cactus, Brady Pincushion Pediocactus bradyi

Cactus, Bunched Cory Coryphantha ramillosa
182

Common and Scientific Name

Cactus, Chisos Mountain Hedgehog Echinocereus chisoensis var. chisoensis

Cactus, Cochise Pincushion Coryphantha robbinsorum

Cactus, Colorado hookless Sclerocactus glaucus

Cactus, Key Tree Pilosocereus robinii

Cactus, Knowlton Pediocactus knowltonii

Cactus, Kuenzler Hedgehog Echinocereus fendleri var. kuenzleri

Cactus, Lee Pincushion Coryphantha sneedii var. leei

Cactus, Lloyd's Mariposa Echinomastus mariposensis

Cactus, Mesa Verde Sclerocactus mesae-verdae

Cactus, Nellie Cory Coryphantha minima

Cactus, Nichol's Turk's Head Echinocactus horizonthalonius var. nicholii

Cactus, Pariette Sclerocactus brevispinus

Cactus, Peebles Navajo Pediocactus peeblesianus peeblesianus

Cactus, Pima Pineapple Coryphantha scheeri var. robustispina

Cactus, San Rafael Pediocactus despainii

Cactus, Siler Pincushion Pediocactus (=Echinocactus,=Utahia) sileri

Cactus, Sneed Pincushion Coryphantha sneedii var. sneedii

Cactus, Star Astrophytum asterias

Cactus, Tobusch Fishhook Ancistrocactus tobuschii

Cactus, Uinta Basin hookless Sclerocactus wetlandicus

Cactus, Winkler Pediocactus winkleri

Cactus, Wright Fishhook Sclerocactus wrightiae

Calyptranthes Thomasiana (ncn) Calyptranthes thomasiana

Campeloma, Slender Campeloma decampi

Campion, Fringed Silene polypetala

Capa Rosa Callicarpa ampla

Caracara, Audubon's Crested Polyborus plancus audubonii

Catchfly, Spalding's Silene spaldingii

Catesbaea Melanocarpa (ncn) Catesbaea melanocarpa

Catfish, Yaqui Ictalurus pricei

Cat's-eye, Terlingua Creek Cryptantha crassipes

Cavefish, Alabama Speoplatyrhinus poulsoni

Cavefish, Ozark Amblyopsis rosae

Cavesnail, Tumbling Creek Antrobia culveri

Ceanothus, Coyote Ceanothus ferrisae

Ceanothus, Pine Hill Ceanothus roderickii

Ceanothus, Vail Lake Ceanothus ophiochilus

Centaury, Spring-loving Centaurium namophilum

Chaffseed, American Schwalbea americana

Chamaecrista glandulosa (ncn) Chamaecrista glandulosa var. mirabilis

Chamaesyce Halemanui (ncn) Chamaesyce halemanui

Checker-mallow, Keck's Sidalcea keckii

Checker-mallow, Kenwood Marsh Sidalcea oregana ssp. valida

Checker-mallow, Nelson's Sidalcea nelsoniana

Checker-mallow, Pedate Sidalcea pedata

Checker-mallow, Wenatchee Mountains Sidalcea oregana var. calva

Choctaw Bean Villosa choctawensis

Chub, Bonytail Gila elegans

Chub, Borax Lake Gila boraxobius

Chub, Chihuahua Gila nigrescens

Chub, Gila Gila intermedia

Chub, Humpback Gila cypha
183

Common and Scientific Name

Chub, Hutton Tui Gila bicolor ssp.

Chub, Mohave Tui Gila bicolor mohavensis

Chub, Oregon Oregonichthys crameri

Chub, Owens Tui Gila bicolor snyderi

Chub, Pahranagat Roundtail Gila robusta jordani

Chub, Slender Erimystax cahni

Chub, Sonora Gila ditaenia

Chub, Spotfin Erimonax monachus

Chub, Virgin River Gila seminuda (=robusta)

Chub, Yaqui Gila purpurea

Chucky Madtom Noturus crypticus

Chumbo, Higo Harrisia portoricensis

Chupacallos Pleodendron macranthum

Cladonia, Florida Perforate Cladonia perforata

Clarkia, Pismo Clarkia speciosa ssp. immaculata

Clarkia, Presidio Clarkia franciscana

Clarkia, Springville Clarkia springvillensis

Clarkia, Vine Hill Clarkia imbricata

Cliffrose, Arizona Purshia (=cowania) subintegra

Clover, Fleshy Owl's Castilleja campestris ssp. succulenta

Clover, Leafy Prairie Dalea foliosa

Clover, Monterey Trifolium trichocalyx

Clover, Prairie Bush Lespedeza leptostachya

Clover, Running Buffalo Trifolium stoloniferum

Clover, Showy Indian Trifolium amoenum

Cobana Negra Stahlia monosperma

Combshell, Southern (=Penitent mussel) Epioblasma penita

Combshell, Upland Epioblasma metastriata

Condor, California Gymnogyps californianus

Coneflower, Smooth Echinacea laevigata

Coot, Hawaiian (=Alae keo keo) Fulica americana alai

Coral, Elkhorn Acropora palmata

Coral, Staghorn Acropora cervicornis

Cordia bellonis (ncn) Cordia bellonis

Coyote-thistle, Loch Lomond Eryngium constancei

Crane, Mississippi Sandhill Grus canadensis pulla

Crane, Whooping Grus americana

Crayfish, Cave (Cambarus aculabrum) Cambarus aculabrum

Crayfish, Cave (Cambarus zophonastes) Cambarus zophonastes

Crayfish, Nashville Orconectes shoupi

Crayfish, Shasta Pacifastacus fortis

Creeper, Hawaii Oreomystis mana

Creeper, Molokai (Kakawahie) Paroreomyza flammea

Creeper, Oahu (Alauwahio) Paroreomyza maculata

Crimson Hawaiian damselfly Megalagrion leptodemas

Crocodile, American Crocodylus acutus

Crow, Hawaiian ('Alala) Corvus hawaiiensis

Crow, Mariana Corvus kubaryi

Crownbeard, Big-leaved Verbesina dissita

Crownscale, San Jacinto Valley Atriplex coronata var. notatior

Cui-ui Chasmistes cujus

Cumberland darter Etheostoma susanae
184

Common and Scientific Name

Curlew, Eskimo Numenius borealis

Cyanea undulata (ncn) Cyanea undulata

Cycladenia, Jones Cycladenia jonesii (=humilis)

Cypress, Gowen Cupressus goveniana ssp. goveniana

Cypress, Santa Cruz Cupressus abramsiana

Dace, Ash Meadows Speckled Rhinichthys osculus nevadensis

Dace, Blackside Phoxinus cumberlandensis

Dace, Clover Valley Speckled Rhinichthys osculus oligoporus

Dace, Desert Eremichthys acros

Dace, Foskett Speckled Rhinichthys osculus ssp.

Dace, Independence Valley Speckled Rhinichthys osculus lethoporus

Dace, Kendall Warm Springs Rhinichthys osculus thermalis

Dace, Moapa Moapa coriacea

Daisy, Lakeside Hymenoxys herbacea

Daisy, Parish's Erigeron parishii

Daisy, Willamette Erigeron decumbens var. decumbens

Damselfly, Flying Earwig Hawaiian Megalagrion nesiotes

Damselfly, Pacific Hawaiian Megalagrion pacificum

Daphnopsis hellerana (ncn) Daphnopsis hellerana

Darter, Amber Percina antesella

Darter, Bayou Etheostoma rubrum

Darter, Bluemask (=jewel) Etheostoma sp.

Darter, Boulder Etheostoma wapiti

Darter, Cherokee Etheostoma scotti

Darter, Duskytail Etheostoma percnurum

Darter, Etowah Etheostoma etowahae

Darter, Fountain Etheostoma fonticola

Darter, Goldline Percina aurolineata

Darter, Leopard Percina pantherina

Darter, Maryland Etheostoma sellare

Darter, Niangua Etheostoma nianguae

Darter, Okaloosa Etheostoma okaloosae

Darter, Relict Etheostoma chienense

Darter, Slackwater Etheostoma boschungi

Darter, Snail Percina tanasi

Darter, Vermilion Etheostoma chermocki

Darter, Watercress Etheostoma nuchale

Dawn-flower, Texas Prairie (=Texas Bitterweed) Hymenoxys texana

DeBeque phacelia Phacelia submutica

Delissea rhytodisperma (ncn) Delissea rhytidosperma

Diellia erecta (ncn) Diellia erecta

Diellia falcata (ncn) Diellia falcata

Diellia pallida (ncn) Diellia pallida

Diellia unisora (ncn) Diellia unisora

Diplazium molokaiense (ncn) Diplazium molokaiense

Dogweed, Ashy Thymophylla tephroleuca

Dragonfly, Hine's Emerald Somatochlora hineana

Dropwort, Canby's Oxypolis canbyi

Dubautia latifolia (ncn) Dubautia latifolia

Dubautia pauciflorula (ncn) Dubautia pauciflorula

Duck, Hawaiian (Koloa) Anas wyvilliana

Duck, Laysan Anas laysanensis
185

Common and Scientific Name

Dudleya, Conejo Dudleya abramsii ssp. parva

Dudleya, Marcescent Dudleya cymosa ssp. marcescens

Dudleya, Santa Clara Valley Dudleya setchellii

Dudleya, Santa Cruz Island Dudleya nesiotica

Dudleya, Santa Monica Mountains Dudleya cymosa ssp. ovatifolia

Dudleya, Verity's Dudleya verityi

Dugong Dugong dugon

Dwarf-flax, Marin Hesperolinon congestum

Eider, Spectacled Somateria fischeri

Eider, Steller's Polysticta stelleri

Elepaio, Oahu Odocoileus virginianus clavium

Elepaio, Oahu Chasiempis sandwichensis ibidis

Elimia, Lacy Elimia crenatella

Elktoe, Appalachian Alasmidonta raveneliana

Erubia Solanum drymophilum

Eugenia Woodburyana Eugenia woodburyana

Evening-primrose, Antioch Dunes Oenothera deltoides ssp. howellii

Evening-primrose, Eureka Valley Oenothera avita ssp. eurekensis

Evening-primrose, San Benito Camissonia benitensis

Fairy Shrimp, Conservancy Fairy Branchinecta conservatio

Fairy Shrimp, Longhorn Branchinecta longiantenna

Fairy Shrimp, Riverside Streptocephalus woottoni

Fairy Shrimp, San Diego Branchinecta sandiegonensis

Fairy Shrimp, Vernal Pool Branchinecta lynchi

Falcon, Northern Aplomado Falco femoralis septentrionalis

Fanshell Cyprogenia stegaria

Fatmucket, Arkansas Lampsilis powelli

Fern, Adiantum vivesii Adiantum vivesii

Fern, Alabama Streak-sorus Thelypteris pilosa var. alabamensis

Fern, Aleutian Shield Polystichum aleuticum

Fern, American hart's-tongue Asplenium scolopendrium var. americanum

Fern, Elaphoglossum serpens Elaphoglossum serpens

Fern, Pendant Kihi (Adenophorus periens) Adenophorus periens

Fern, Thelypteris inabonensis Thelypteris inabonensis

Fern, Thelypteris verecunda Thelypteris verecunda

Fern, Thelypteris yaucoensis Thelypteris yaucoensis

Fiddleneck, Large-flowered Amsinckia grandiflora

Finch, Laysan Telespyza cantans

Finch, Nihoa Telespyza ultima

Flannelbush, Mexican Fremontodendron mexicanum

Flannelbush, Pine Hill Fremontodendron californicum ssp. decumbens

Fleabane, Zuni Erigeron rhizomatus

Fly, Delhi Sands Flower-loving Rhaphiomidas terminatus abdominalis

Fly, Hawaiian picture-wing Drosophila aglaia

Fly, Hawaiian picture-wing Drosophila heteroneura

Fly, Hawaiian picture-wing Drosophila montgomeryi

Fly, Hawaiian picture-wing Drosophila mulli

Fly, Hawaiian picture-wing Drosophila musaphilia

Fly, Hawaiian picture-wing Drosophila neoclavisetae

Fly, Hawaiian picture-wing Drosophila obatai

Fly, Hawaiian picture-wing Drosophila substenoptera

Fly, Hawaiian picture-wing Drosophila tarphytrichia
186

Common and Scientific Name

Fly, Hawaiian picture-wing Drosophila hemipeza

Fly, Hawaiian picture-wing Drosophila ochrobasis

Fly, Hawaiian picture-wing Drosophila differens

Flycatcher, Southwestern Willow Empidonax traillii extimus

Four-o'clock, Macfarlane's Mirabilis macfarlanei

Frankenia, Johnston's Frankenia johnstonii

Fringe Tree, Pygmy Chionanthus pygmaeus

Fringepod, Santa Cruz Island Thysanocarpus conchuliferus

Frog, California Red-legged Rana aurora draytonii

Frog, Chiricahua Leopard Rana chiricahuensis

Frog, Dusky Gopher (Mississippi DPS) Rana capito sevosa

Frog, Mountain Yellow-legged Rana muscosa

Fruit, Earth (=geocarpon) Geocarpon minimum

fuzzy pigtoe Pleurobema strodeanum

Gahnia Lanaiensis (ncn) Gahnia lanaiensis

Gambusia, Big Bend Gambusia gaigei

Gambusia, Clear Creek Gambusia heterochir

Gambusia, Pecos Gambusia nobilis

Gambusia, San Marcos Gambusia georgei

Gecko, Monito Sphaerodactylus micropithecus

Geranium, Hawaiian Red-flowered Geranium arboreum

Gerardia, Sandplain Agalinis acuta

Gesneria pauciflora (ncn) Gesneria pauciflora

Gilia, Hoffmann's Slender-flowered Gilia tenuiflora ssp. hoffmannii

Gilia, Monterey Gilia tenuiflora ssp. arenaria

Gnatcatcher, Coastal California Polioptila californica californica

Goby, Tidewater Eucyclogobius newberryi

Goetzea, Beautiful (Matabuey) Goetzea elegans

Golden Sunburst, Hartweg's Pseudobahia bahiifolia

Goldenrod, Blue Ridge Solidago spithamaea

Goldenrod, Houghton's Solidago houghtonii

Goldenrod, Short's Solidago shortii

Goldenrod, White-haired Solidago albopilosa

Goldfields, Burke's Lasthenia burkei

Goldfields, Contra Costa Lasthenia conjugens

Goose, Hawaiian (Nene) Branta (=Nesochen) sandvicensis

Gooseberry, Miccosukee Ribes echinellum

Gouania hillebrandii (ncn) Gouania hillebrandii

Gouania meyenii (ncn) Gouania meyenii

Gouania vitifolia (ncn) Gouania vitifolia

Gourd, Okeechobee Cucurbita okeechobeensis ssp. okeechobeensis

Grass, Hairy Orcutt Orcuttia pilosa

Grass, Sacramento Orcutt Orcuttia viscida

Grass, Slender Orcutt Orcuttia tenuis

Grasshopper, Zayante Band-winged Trimerotropis infantilis

Ground-plum, Guthrie's Astragalus bibullatus

Groundsel, San Francisco Peaks Senecio franciscanus

Gumplant, Ash Meadows Grindelia fraxino-pratensis

ha`iwale Cyrtandra kaulantha

ha`iwale Cyrtandra sessilis

Haha Cyanea lanceolata

Haha Cyanea calycina
187

Common and Scientific Name

haha Cyanea purpurellifolia

Haha Cyanea kuhihewa

haha Cyanea eleeleensis

Haha Cyanea dolichopoda

Haha (Cyanea acuminata) Cyanea acuminata

Haha (Cyanea asarifolia) Cyanea asarifolia

Haha (Cyanea copelandii ssp. copelandii) Cyanea copelandii ssp. copelandii

Haha (Cyanea copelandii ssp. haleakalaensis) Cyanea copelandii ssp. haleakalaensis

Haha (Cyanea Crispa) (=Rollandia crispa) Cyanea (=Rollandia) crispa

Haha (Cyanea dunbarii) Cyanea dunbarii

Haha (Cyanea glabra) Cyanea glabra

Haha (Cyanea grimesiana ssp. grimesiana) Cyanea grimesiana ssp. grimesiana

Haha (Cyanea grimesiana ssp. obatae) Cyanea grimesiana ssp. obatae

Haha (Cyanea hamatiflora ssp. carlsonii) Cyanea hamatiflora ssp. Carlsonii

Haha (Cyanea hamatiflora ssp. hamatiflora) Cyanea hamatiflora ssp. hamatiflora

Haha (Cyanea humboldtiana) Cyanea humboldtiana

Haha (Cyanea koolauensis) Cyanea koolauensis

Haha (Cyanea lobata) Cyanea lobata

Haha (Cyanea longiflora) Cyanea longiflora

Haha (Cyanea Macrostegia var. gibsonii) Cyanea macrostegia ssp. gibsonii

Haha (Cyanea mannii) Cyanea mannii

Haha (Cyanea mceldowneyi) Cyanea mceldowneyi

Haha (Cyanea pinnatifida) Cyanea pinnatifida

Haha (Cyanea platyphylla) Cyanea platyphylla

Haha (Cyanea procera) Cyanea procera

Haha (Cyanea recta) Cyanea recta

Haha (Cyanea remyi) Cyanea remyi

Haha (Cyanea shipmanii) Cyanea shipmannii

Haha (Cyanea stictophylla) Cyanea stictophylla

Haha (Cyanea St-Johnii) (=Rollandia St-Johnii) Cyanea st-johnii

Haha (Cyanea superba) Cyanea superba

Haha (Cyanea truncata) Cyanea truncata

haiwale Cyrtandra waiolani

haiwale Cyrtandra gracilis

haiwale Cyrtandra paliku

Ha'Iwale (Cyrtandra crenata) Cyrtandra crenata

Ha'Iwale (Cyrtandra dentata) Cyrtandra dentata

Ha'Iwale (Cyrtandra giffardii) Cyrtandra giffardii

Ha'Iwale (Cyrtandra limahuliensis) Cyrtandra limahuliensis

Ha'Iwale (Cyrtandra munroi) Cyrtandra munroi

Ha'iwale (Cyrtandra oenobarba) Cyrtandra oenobarba

Ha'Iwale (Cyrtandra polyantha) Cyrtandra polyantha

Ha'Iwale (Cyrtandra subumbellata) Cyrtandra subumbellata

Ha'Iwale (Cyrtandra tintinnabula) Cyrtandra tintinnabula

Ha'Iwale (Cyrtandra viridiflora) Cyrtandra viridiflora

Haplostachys Haplostachya (ncn) Haplostachys haplostachya

Harebells, Avon Park Crotalaria avonensis

Harperella Ptilimnium nodosum

Harvestman, Bee Creek Cave Texella reddelli

Harvestman, Bone Cave Texella reyesi

Harvestman, Cokendolpher Cave Texella cokendolpheri

Hau Kauhiwi (Hibiscadelphus woodi) Hibiscadelphus woodii
188

Common and Scientific Name

Hau Kuahiwi (Hibiscadelphus distans) Hibiscadelphus distans

Hau Kuahiwi (Hibiscadelphus giffardianus) Hibiscadelphus giffardianus

Hau Kuahiwi (Hibiscadelphus hualalaiensis) Hibiscadelphus hualalaiensis

Hawaiian picture-wing Fly Drosophila sharpi

Hawk, Hawaiian (Io) Buteo solitarius

Hawk, Puerto Rican Broad-winged Buteo platypterus brunnescens

Hawk, Puerto Rican Sharp-shinned Accipiter striatus venator

Hayun Lagu (Tronkon Guafi) Serianthes nelsonii

Heartleaf, Dwarf-flowered Hexastylis naniflora

Heather, Mountain Golden Hudsonia montana

Heau (Exocarpos luteolus) Exocarpos luteolus

Hedyotis degeneri (ncn) Hedyotis degeneri

Hedyotis parvula (ncn) Hedyotis parvula

Hedyotis St.-Johnii (ncn) Hedyotis st.-johnii

Hesperomannia arborescens (ncn) Hesperomannia arborescens

Hesperomannia arbuscula (ncn) Hesperomannia arbuscula

Hesperomannia lydgatei (ncn) Hesperomannia lydgatei

Hibiscus, Clay's Hibiscus clayi

Higuero De Sierra Crescentia portoricensis

ho'awa Pittosporum napaliense

Holei (Ochrosia kilaueaensis) Ochrosia kilaueaensis

Holly, Cook's Ilex cookie

Honeycreeper, Crested ('Akohekohe) Palmeria dolei

Hornsnail, rough Pleurocera foremani

Howellia, Water Howellia aquatilis

Hypericum, Highlands Scrub Hypericum cumulicola

Iguana, Mona Ground Cyclura cornuta stejnegeri

'Ihi'Ihi (Marsilea villosa) Marsilea villosa

Ilex sintenisii (ncn) Ilex sintenisii

Iliau (Wilkesia hobdyi) Wilkesia hobdyi

Ipomopsis, Holy Ghost Ipomopsis sancti-spiritus

Isopod, Lee County Cave Lirceus usdagalun

Isopod, Madison Cave Antrolana lira

Isopod, Socorro Thermosphaeroma thermophilus

Ivesia, Ash Meadows Ivesia kingii var. eremica

Jacquemontia, Beach Jacquemontia reclinata

Jewelflower, California Caulanthus californicus

Jewelflower, Metcalf Canyon Streptanthus albidus ssp. albidus

Jewelflower, Tiburon Streptanthus niger

Joint-vetch, Sensitive Aeschynomene virginica

kamakahala Labordia helleri

kamakahala Labordia pumila

Kamakahala (Labordia cyrtandrae) Labordia cyrtandrae

Kamakahala (Labordia lydgatei) Labordia lydgatei

Kamakahala (Labordia tinifolia var. lanaiensis) Labordia tinifolia var. lanaiensis

Kamakahala (Labordia tinifolia var. wahiawaen) Labordia tinifolia var. wahiawaensis

Kamakahala (Labordia triflora) Labordia triflora

Kanaloa kahoolawensis (ncn) Kanaloa kahoolawensis

Kauai creeper Oreomystis bairdi

Kauila (Colubrina oppositifolia) Colubrina oppositifolia

kaulu Pteralyxia macrocarpa

Kaulu (Pteralyxia kauaiensis) Pteralyxia kauaiensis
189

Common and Scientific Name

Kidneyshell, Triangular Ptychobranchus greenii

Kingfisher, Guam Micronesian Halcyon cinnamomina cinnamomina

Kio'Ele (Hedyotis coriacea) Hedyotis coriacea

Kiponapona (Phyllostegia racemosa) Phyllostegia racemosa

Kite, Everglades Snail Rostrhamus sociabilis plumbeus

ko`oko`olau Bidens amplectens

Koki'o (Kokia drynarioides) Kokia drynarioides

Koki'o (Kokia kauaiensis) Kokia kauaiensis

Koki'o Ke'oke'o (Hibiscus arnottianus ssp. 

immaculatus) Hibiscus arnottianus ssp. immaculatus

Koki'o Ke'oke'o (Hibiscus waimeae ssp. hannerae) Hibiscus waimeae ssp. hannerae

Koki'o, Cooke's (Kokia cookei) Kokia cookie

kolea Myrsine mezii

Kolea Myrsine knudsenii

Kolea (Myrsine juddii) Myrsine juddii

Kolea (Myrsine linearifolia) Myrsine linearifolia

Ko'oko'olau (Bidens micrantha ssp. kalealaha) Bidens micrantha ssp. kalealaha

Ko'oko'olau (Bidens wiebkei) Bidens wiebkei

Ko'oloa'ula (Abutilon menziesii) Abutilon menziesii

Kopa (Hedyotis schlechtendahliana var. remyi) Hedyotis schlechtendahliana var. remyi

kopiko Psychotria grandiflora

kopiko Psychotria hobdyi

Kuawawaenohu (Alsinidendron lychnoides) Alsinidendron lychnoides

Kulu'I (Nototrichium humile) Nototrichium humile

Larkspur, Baker's Delphinium bakeri

Larkspur, San Clemente Island Delphinium variegatum ssp. kinkiense

Larkspur, Yellow Delphinium luteum

Laukahi Kuahiwi (Plantago hawaiensis) Plantago hawaiensis

Laukahi Kuahiwi (Plantago princeps) Plantago princeps

Laulihilihi (Schiedea stellarioides) Schiedea stellarioides

Laurel dace Chrosomus aylori

Layia, Beach Layia carnosa

Lead-plant, Crenulate Amorpha crenulata

Leather-flower, Alabama Clematis socialis

Leather-flower, Morefield's Clematis morefieldii

lehua makanoe Lysimachia daphnoides

Leptocereus grantianus (ncn) Leptocereus grantianus

Lessingia, San Francisco Lessingia germanorum (=L.g. var. germanorum)

Lichen, Rock Gnome Gymnoderma lineare

Liliwai (Acaena exigua) Acaena exigua

Limpet, Banbury Springs Lanx sp.

Lipochaeta venosa (ncn) Lipochaeta venosa

Liveforever, Laguna Beach Dudleya stolonifera

Liveforever, Santa Barbara Island Dudleya traskiae

Lizard, Blunt-nosed Leopard Gambelia silus

Lizard, Coachella Valley Fringe-toed Uma inornata

Lizard, Island Night Xantusia riversiana

Lizard, St. Croix Ground Ameiva polops

Lo`ulu (Pritchardia munroi) Pritchardia munroi

Lo`ulu (Pritchardia remota) Pritchardia remota

Lobelia monostachya (ncn) Lobelia monostachya

Lobelia niihauensis (ncn) Lobelia niihauensis
190

Common and Scientific Name

Lobelia oahuensis (ncn) Lobelia oahuensis

Locoweed, Fassett's Oxytropis campestris var. chartacea

Logperch, Conasauga Percina jenkinsi

Logperch, Roanoke Percina rex

Lomatium, Bradshaw's Lomatium bradshawii

Lomatium, Cook's Lomatium cookii

Loosestrife, Rough-leaved Lysimachia asperulaefolia

Lousewort, Furbish Pedicularis furbishiae

Lupine, Clover Lupinus tidestromii

Lupine, Kincaid's

Lupinus sulphureus (=oreganus) ssp. kincaidii 

(=var. kincaidii)

Lupine, Nipomo Mesa Lupinus nipomensis

Lupine, Scrub Lupinus aridorum

Lyonia truncata var. proctorii (ncn) Lyonia truncata var. proctorii

Lysimachia filifolia (ncn) Lysimachia filifolia

Lysimachia lydgatei (ncn) Lysimachia lydgatei

Lysimachia maxima (ncn) Lysimachia maxima

Madtom, Neosho Noturus placidus

Madtom, Pygmy Noturus stanauli

Madtom, Scioto Noturus trautmani

Madtom, Smoky Noturus baileyi

Madtom, Yellowfin Noturus flavipinnis

Mahoe (Alectryon macrococcus) Alectryon macrococcus

Makou (Peucedanum sandwicense) Peucedanum sandwicense

Malacothrix, Island Malacothrix squalida

Malacothrix, Santa Cruz Island Malacothrix indecora

Mallow, Kern Eremalche kernensis

Mallow, Peter's Mountain Iliamna corei

Manioc, Walker's Manihot walkerae

Manzanita, Del Mar Arctostaphylos glandulosa ssp. crassifolia

Manzanita, Ione Arctostaphylos myrtifolia

Manzanita, Morro Arctostaphylos morroensis

Manzanita, Pallid Arctostaphylos pallida

Manzanita, Presidio (=Raven's) Arctostaphylos hookeri var. ravenii

Manzanita, Santa Rosa Island Arctostaphylos confertiflora

Ma'o Hau Hele (Hibiscus brackenridgei) Hibiscus brackenridgei

Ma'oli'oli (Schiedea apokremnos) Schiedea apokremnos

Ma'oli'oli (Schiedea kealiae) Schiedea kealiae

Mapele (Cyrtandra cyaneoides) Cyrtandra cyaneoides

Marstonia, Royal (=Royal Snail) Pyrgulopsis ogmorhaphe

Meadowfoam, Butte County Limnanthes floccosa ssp. californica

Meadowfoam, Large-flowered Woolly Limnanthes floccosa ssp. Grandiflora

Meadowfoam, Sebastopol Limnanthes vinculans

Meadowrue, Cooley's Thalictrum cooleyi

Megapode, Micronesian (La Perouse's) Megapodius laperouse

Mehamehame (Flueggea neowawraea) Flueggea neowawraea

Meshweaver, Braken Bat Cave Cicurina venii

Meshweaver, Government Canyon Bat Cave Cicurina vespera

Meshweaver, Madla's Cave Cicurina madla

Meshweaver, Robber Baron Cave Cicurina baronia

Milkpea, Small's Galactia smallii

Milk-vetch, Applegate's Astragalus applegatei
191

Common and Scientific Name

Milk-vetch, Ash Meadows Astragalus phoenix

Milk-vetch, Braunton's Astragalus brauntonii

Milk-vetch, Clara Hunt's Astragalus clarianus

Milk-vetch, Coachella Valley Astragalus lentiginosus var. coachellae

Milk-vetch, Coastal Dunes Astragalus tener var. titi

Milk-vetch, Cushenbury Astragalus albens

Milk-vetch, Deseret Astragalus desereticus

Milk-vetch, Fish Slough Astragalus lentiginosus var. piscinensis

Milk-vetch, Heliotrope Astragalus montii

Milk-vetch, Holmgren Astragalus holmgreniorum

Milk-vetch, Jesup's Astragalus robbinsii var. jesupi

Milk-vetch, Lane Mountain Astragalus jaegerianus

Milk-vetch, Mancos Astragalus humillimus

Milk-vetch, Osterhout Astragalus osterhoutii

Milk-vetch, Pierson's Astragalus magdalenae var. peirsonii

Milk-vetch, Sentry Astragalus cremnophylax var. cremnophylax

Milk-vetch, Shivwits Astragalus ampullarioides

Milk-vetch, Triple-ribbed Astragalus tricarinatus

Milk-vetch, Ventura Marsh Astragalus pycnostachyus var. lanosissimus

Milkweed, Mead's Asclepias meadii

Milkweed, Welsh's Asclepias welshii

Millerbird, Nihoa Acrocephalus familiaris kingi

Minnow, Devils River Dionda diaboli

Minnow, Loach Tiaroga cobitis

Minnow, Rio Grande Silvery Hybognathus amarus

Mint, Garrett's Dicerandra christmanii

Mint, Lakela's Dicerandra immaculata

Mint, Longspurred Dicerandra cornutissima

Mint, Otay Mesa Pogogyne nudiuscula

Mint, San Diego Mesa Pogogyne abramsii

Mint, Scrub Dicerandra frutescens

Mitracarpus Maxwelliae Mitracarpus maxwelliae

Mitracarpus Polycladus Mitracarpus polycladus

Monardella, Willowy Monardella linoides ssp. viminea

Monkey-flower, Michigan Mimulus glabratus var. michiganensis

Monkshood, Northern Wild Aconitum noveboracense

Moorhen, Hawaiian Common Gallinula chloropus sandvicensis

Moorhen, Mariana Common Gallinula chloropus guami

Morning-glory, Stebbins Calystegia stebbinsii

Moth, Blackburn's Sphinx Manduca blackburni

Moth, Kern Primrose Sphinx Euproserpinus euterpe

Mountainbalm, Indian Knob Eriodictyon altissimum

Mountain-mahogany, Catalina Island Cercocarpus traskiae

Mouse, Key Largo Cotton Peromyscus gossypinus allapaticola

Mucket, Orange-nacre Lampsilis perovalis

Mucket, Pink (Pearlymussel) Lampsilis abrupta

Munroidendron racemosum (ncn) Munroidendron racemosum

Murrelet, Marbled Brachyramphus marmoratus

Mussel, Acornshell Southern Epioblasma othcaloogensis

Mussel, Alabama Moccasinshell Medionidus acutissimus

Mussel, Black (=Curtus' Mussel) Clubshell Pleurobema curtum

Mussel, Clubshell Pleurobema clava
192

Common and Scientific Name

Mussel, Coosa Moccasinshell Medionidus parvulus

Mussel, Cumberland Combshell Epioblasma brevidens

Mussel, Cumberland Elktoe Alasmidonta atropurpurea

Mussel, Cumberland Pigtoe Pleurobema gibberum

Mussel, Dark Pigtoe Pleurobema furvum

Mussel, Dwarf Wedge Alasmidonta heterodon

Mussel, Fat Threeridge Amblema neislerii

Mussel, Fine-lined Pocketbook Lampsilis altilis

Mussel, Fine-rayed Pigtoe Fusconaia cuneolus

Mussel, Flat Pigtoe (=Marshall's Mussel) Pleurobema marshalli

Mussel, Georgia pigtoe Pleurobema hanleyianum

Mussel, Gulf Moccasinshell Medionidus penicillatus

Mussel, Heavy Pigtoe (=Judge Tait's Mussel) Pleurobema taitianum

Mussel, Heelsplitter Carolina Lasmigona decorata

Mussel, Heelsplitter Inflated Potamilus inflatus

Mussel, Ochlockonee Moccasinshell Medionidus simpsonianus

Mussel, Oval Pigtoe Pleurobema pyriforme

Mussel, Ovate Clubshell Pleurobema perovatum

Mussel, Oyster Epioblasma capsaeformis

Mussel, Ring Pink (=Golf Stick Pearly) Obovaria retusa

Mussel, Rough Pigtoe Pleurobema plenum

Mussel, Scaleshell Leptodea leptodon

Mussel, Shiny Pigtoe Fusconaia cor

Mussel, Shiny-rayed Pocketbook Lampsilis subangulata

Mussel, snuffbox Epioblasma triquetra

Mussel, Southern Clubshell Pleurobema decisum

Mussel, Southern Pigtoe Pleurobema georgianum

Mussel, Speckled Pocketbook Lampsilis streckeri

Mussel, Winged Mapleleaf Quadrula fragosa

Mustard, Carter's Warea carteri

Mustard, Penland Alpine Fen Eutrema penlandii

Mustard, Slender-petaled Thelypodium stenopetalum

Myrcia Paganii Myrcia paganii

Na`ena`e Dubautia waialealae

na`ena`e Dubautia imbricata imbricata

na`ena`e Dubautia plantaginea magnifolia

Naenae Dubautia kalalauensis

Naenae Dubautia kenwoodii

Na'ena'e (Dubautia herbstobatae) Dubautia herbstobatae

Na'ena'e (Dubautia plantaginea ssp. humilis) Dubautia plantaginea ssp. humilis

Nani Wai'ale'ale (Viola kauaensis var. wahiawaensis) Viola kauaiensis var. wahiawaensis

Nanu (Gardenia mannii) Gardenia mannii

Narrow Pigtoe Fusconaia escambia

Na'u (Gardenia brighamii) Gardenia brighamii

Naucorid, Ash Meadows Ambrysus amargosus

Naupaka, Dwarf (Scaevola coriacea) Scaevola coriacea

Navarretia, Few-flowered Navarretia leucocephala ssp. Pauciflora

Navarretia, Many-flowered Navarretia leucocephala ssp. plieantha

Navarretia, Spreading Navarretia fossalis

Nehe (Lipochaeta fauriei) Lipochaeta fauriei

Nehe (Lipochaeta kamolensis) Lipochaeta kamolensis

Nehe (Lipochaeta lobata var. leptophylla) Lipochaeta lobata var. leptophylla
193

Common and Scientific Name

Nehe (Lipochaeta micrantha) Lipochaeta micrantha

Nehe (Lipochaeta tenuifolia) Lipochaeta tenuifolia

Nehe (Lipochaeta waimeaensis) Lipochaeta waimeaensis

Neraudia angulata (ncn) Neraudia angulata

Neraudia ovata (ncn) Neraudia ovata

Neraudia sericea (ncn) Neraudia sericea

Nesogenes rotensis (ncn) Nesogenes rotensis

Nightjar, Puerto Rico Caprimulgus noctitherus

Nioi (Eugenia koolauensis) Eugenia koolauensis

Niterwort, Amargosa Nitrophila mohavensis

nohoanu Geranium kauaiense

Nohoanu (Geranium multiflorum) Geranium multiflorum

Nuku Pu'u, Kauai Hemignathus lucidus hanapepe

Nuku Pu'u, Maui Hemignathus lucidus affinus

Oahu wild coffee Psychotria hexandra ssp. Oahuensis

Oak, Hinckley Quercus hinckleyi

Oceanic Hawaiian damselfly Megalagrion oceanicum

'Oha (Delissea rivularis) Delissea rivularis

'Oha (Delissea subcordata) Delissea subcordata

'Oha (Delissea undulata) Delissea undulata

'Oha (Lobelia gaudichaudii koolauensis) Lobelia gaudichaudii ssp. koolauensis

'Oha Wai (Clermontia drepanomorpha) Clermontia drepanomorpha

'Oha Wai (Clermontia lindseyana) Clermontia lindseyana

'Oha Wai (Clermontia oblongifolia ssp. brevipes) Clermontia oblongifolia ssp. brevipes

'Oha Wai (Clermontia oblongifolia ssp. mauiensis) Clermontia oblongifolia ssp. mauiensis

'Oha Wai (Clermontia peleana) Clermontia peleana

'Oha Wai (Clermontia pyrularia) Clermontia pyrularia

'Oha Wai (Clermontia samuelii) Clermontia samuelii

'Ohai (Sesbania tomentosa) Sesbania tomentosa

'Ohe'ohe (Tetraplasandra gymnocarpa) Tetraplasandra gymnocarpa

'Olulu (Brighamia insignis) Brighamia insignis

'O'o, Kauai (='A'a) Moho braccatus

Opuhe (Urera kaalae) Urera kaalae

Osmoxylon mariannense (ncn) Osmoxylon mariannense

Otter, Northern Sea Enhydra lutris kenyoni

'O'u (Honeycreeper) Psittirostra psittacea

Owl, Mexican Spotted Strix occidentalis lucida

Owl, Northern Spotted Strix occidentalis caurina

Oxytheca, Cushenbury Oxytheca parishii var. goodmaniana

Ozark Hellbender Cryptobranchus alleganiensis bishopi

Pagosa Skyrocket Ipomopsis polyantha

Paintbrush, Ash-grey Indian Castilleja cinerea

Paintbrush, Golden Castilleja levisecta

Paintbrush, San Clemente Island Indian Castilleja grisea

Paintbrush, Soft-leaved Castilleja mollis

Paintbrush, Tiburon Castilleja affinis ssp. neglecta

Palila Loxioides bailleui

Palo Colorado (Ternstroemia luquillensis) Ternstroemia luquillensis

Palo de Jazmin Styrax portoricensis

Palo de Nigua Cornutia obovata

Palo de Ramon Banara vanderbiltii

Palo de Rosa Ottoschulzia rhodoxylon
194

Common and Scientific Name

Pamakani (Viola chamissoniana ssp. chamissoniana) Viola chamissoniana ssp. chamissoniana

Papala Charpentiera densiflora

Parachute Beardtongue Penstemon debilis

Parrot, Puerto Rican Amazona vittata

Parrotbill, Maui Pseudonestor xanthophrys

Pauoa (Ctenitis squamigera) Ctenitis squamigera

Pawpaw, Beautiful Deeringothamnus pulchellus

Pawpaw, Four-petal Asimina tetramera

Pawpaw, Rugel's Deeringothamnus rugelii

Pearlshell, Louisiana Margaritifera hembeli

Pearlymussel, Alabama Lamp Lampsilis virescens

Pearlymussel, Appalachian Monkeyface Quadrula sparsa

Pearlymussel, Birdwing Lemiox rimosus

Pearlymussel, Cracking Hemistena lata

Pearlymussel, Cumberland Bean Villosa trabalis

Pearlymussel, Cumberland Monkeyface Quadrula intermedia

Pearlymussel, Curtis' Epioblasma florentina curtisii

Pearlymussel, Dromedary Dromus dromas

Pearlymussel, Fat Pocketbook Potamilus capax

Pearlymussel, Green-blossom Epioblasma torulosa gubernaculum

Pearlymussel, Higgins' Eye Lampsilis higginsii

Pearlymussel, Little-wing Pegias fibula

Pearlymussel, Orange-footed Plethobasus cooperianus

Pearlymussel, Pale Lilliput Toxolasma cylindrellus

Pearlymussel, Purple Cat's Paw Epioblasma obliquata obliquata

Pearlymussel, Tubercled-blossom Epioblasma torulosa torulosa

Pearlymussel, Turgid-blossom Epioblasma turgidula

Pearlymussel, White Cat's Paw Epioblasma obliquata perobliqua

Pearlymussel, White Wartyback Plethobasus cicatricosus

Pearlymussel, Yellow-blossom Epioblasma florentina florentina

Pebblesnail, Flat Lepyrium showalteri

Penny-cress, Kneeland Prairie Thlaspi californicum

Pennyroyal, Todsen's Hedeoma todsenii

Penstemon, Blowout Penstemon haydenii

Pentachaeta, Lyon's Pentachaeta lyonii

Pentachaeta, White-rayed Pentachaeta bellidiflora

Peperomia, Wheeler's Peperomia wheeleri

Peppergrass, Slick Spot Lepidium papilliferum

Petrel, Hawaiian Dark-rumped Pterodroma phaeopygia sandwichensis

Phacelia, Clay Phacelia argillacea

Phacelia, Island Phacelia insularis ssp. insularis

Phacelia, North Park Phacelia formosula

Phlox, Texas Trailing Phlox nivalis ssp. texensis

Phlox, Yreka Phlox hirsuta

Phyllostegia hirsuta (ncn) Phyllostegia hirsuta

Phyllostegia kaalaensis (ncn) Phyllostegia kaalaensis

Phyllostegia knudsenii (ncn) Phyllostegia knudsenii

Phyllostegia mannii (ncn) Phyllostegia mannii

Phyllostegia mollis (ncn) Phyllostegia mollis

Phyllostegia parviflora (ncn) Phyllostegia parviflora

Phyllostegia velutina (ncn) Phyllostegia velutina

Phyllostegia waimeae (ncn) Phyllostegia waimeae
195

Common and Scientific Name

Phyllostegia warshaueri (ncn) Phyllostegia warshaueri

Phyllostegia wawrana (ncn) Phyllostegia wawrana

Pigeon, Puerto Rican Plain Columba inornata wetmorei

Pilo (Hedyotis mannii) Hedyotis mannii

pilo kea lau li`i Platydesma rostrata

Pinkroot, Gentian Spigelia gentianoides

Pitaya, Davis' Green Echinocereus viridiflorus var. davisii

Pitcher-plant, Alabama Canebrake Sarracenia rubra alabamensis

Pitcher-plant, Green Sarracenia oreophila

Pitcher-plant, Mountain Sweet Sarracenia rubra ssp. jonesii

Plover, Piping Charadrius melodus

Plover, Western Snowy Charadrius alexandrinus nivosus

Plum, Scrub Prunus geniculata

Po'e (Portulaca sclerocarpa) Portulaca sclerocarpa

Polygala, Lewton's Polygala lewtonii

Polygala, Tiny Polygala smallii

Polygonum, Scott's Valley Polygonum hickmanii

Polystichum calderonense (ncn) Polystichum calderonense

Pondberry Lindera melissifolia

Pondweed, Little Aguja Creek Potamogeton clystocarpus

Poolfish, Pahrump (= Pahrump Killifish) Empetrichthys latos

Po'ouli Melamprosops phaeosoma

Popcornflower, Rough Plagiobothrys hirtus

Popolo 'Aiakeakua (Solanum sandwicense) Solanum sandwicense

Popolo Ku Mai (Solanum incompletum) Solanum incompletum

Poppy, Sacramento Prickly Argemone pleiacantha ssp. pinnatisecta

Poppy-mallow, Texas Callirhoe scabriuscula

Potato-bean, Price's Apios priceana

Potentilla, Hickman's Potentilla hickmanii

Prairie-chicken, Attwater's Greater Tympanuchus cupido attwateri

Prickly-apple, Fragrant Cereus eriophorus var. fragrans

Prickly-ash, St. Thomas Zanthoxylum thomasianum

Primrose, Maguire Primula maguirei

Pseudoscorpion, Tooth Cave Tartarocreagris texana

Pteris lidgatei (ncn) Pteris lidgatei

Pua'ala (Brighamia rockii) Brighamia rockii

Pupfish, Ash Meadows Amargosa Cyprinodon nevadensis mionectes

Pupfish, Comanche Springs Cyprinodon elegans

Pupfish, Desert Cyprinodon macularius

Pupfish, Devils Hole Cyprinodon diabolis

Pupfish, Leon Springs Cyprinodon bovinus

Pupfish, Owens Cyprinodon radiosus

Pupfish, Warm Springs Cyprinodon nevadensis pectoralis

Purple Bean Villosa perpurpurea

Pussypaws, Mariposa Calyptridium pulchellum

Quillwort, Black-spored Isoetes melanospora

Quillwort, Louisiana Isoetes louisianensis

Quillwort, Mat-forming Isoetes tegetiformans

Rabbit, Lower Keys Marsh Sylvilagus palustris hefneri

Rabbitsfoot, Rough Quadrula cylindrica strigillata

Rail, California Clapper Rallus longirostris obsoletus

Rail, Guam Rallus owstoni
196

Common and Scientific Name

Rail, Light-footed Clapper Rallus longirostris levipes

Rail, Yuma Clapper Rallus longirostris yumanensis

Rattlesnake, New Mexican Ridge-nosed Crotalus willardi obscurus

Rattleweed, Hairy Baptisia arachnifera

Rayed Bean Villosa fabalis

Reed-mustard, Barneby Schoenocrambe barnebyi

Reed-mustard, Clay Schoenocrambe argillacea

Reed-mustard, Shrubby Schoenocrambe suffrutescens

Remya kauaiensis (ncn) Remya kauaiensis

Remya montgomeryi (ncn) Remya montgomeryi

Remya, Maui Remya mauiensis

Rhadine exilis (ncn) Rhadine exilis

Rhadine infernalis (ncn) Rhadine infernalis

Rhododendron, Chapman Rhododendron chapmanii

Rice Rat (=Silver Rice Rat) Oryzomys palustris natator

Ridge-cress (=Pepper-cress), Barneby Lepidium barnebyanum

Riffleshell, Northern Epioblasma torulosa rangiana

Riffleshell, Tan Epioblasma florentina walkeri (=E. walkeri)

Riversnail, Anthony's Athearnia anthonyi

Rock-cress, Braun's Arabis perstellata E. L. Braun var. ampla Rollins

Rock-cress, Hoffmann's Arabis hoffmannii

Rock-cress, McDonald's Arabis mcdonaldiana

Rock-cress, Santa Cruz Island Sibara filifolia

Rock-cress, Shale Barren Arabis serotina

Rock-cress, Small

Arabis perstellata E. L. Braun var. perstellata 

Fernald

Rockfish, Bocaccio Sebastes paucispinis

Rockfish, Canary Sebastes pinniger

Rock-pocketbook, Ouachita (=Wheeler's pm) Arkansia wheeleri

Rocksnail, interrupted Leptoxis foremani

Rocksnail, Painted Leptoxis taeniata

Rocksnail, Plicate Leptoxis plicata

Rocksnail, Round Leptoxis ampla

Rosemary, Apalachicola Conradina glabra

Rosemary, Cumberland Conradina verticillata

Rosemary, Etonia Conradina etonia

Rosemary, Short-leaved Conradina brevifolia

Roseroot, Leedy's Sedum integrifolium ssp. leedyi

Round Ebonyshell Fusconaia rotulata

Rush darter Etheostoma phytophilum

Rush-pea, Slender Hoffmannseggia tenella

Rush-rose, Island Helianthemum greenei

Salamander, Barton Springs Eurycea sosorum

Salamander, California Tiger Ambystoma californiense

Salamander, Cheat Mountain Plethodon nettingi

Salamander, Desert Slender Batrachoseps aridus

Salamander, Frosted Flatwoods Ambystoma cingulatum

Salamander, Red Hills Phaeognathus hubrichti

Salamander, Reticulated flatwoods Ambystoma bishopi

Salamander, San Marcos Eurycea nana

Salamander, Santa Cruz Long-toed Ambystoma macrodactylum croceum

Salamander, Shenandoah Plethodon shenandoah
197

Common and Scientific Name

Salamander, Sonora Tiger Ambystoma tigrinum stebbinsi

Salamander, Texas Blind Typhlomolge rathbuni

Salmon, Atlantic Salmo salar

Salmon, Chinook Oncorhynchus (=Salmo) tshawytscha

Salmon, Chum Oncorhynchus (=Salmo) keta

Salmon, Coho Oncorhynchus (=Salmo) kisutch

Salmon, Sockeye Oncorhynchus (=Salmo) nerka

San Francisco manzanita Arctostaphylos franciscana

Sandalwood, Lanai (='Iliahi) Santalum freycinetianum var. lanaiense

Sandlace Polygonella myriophylla

Sand-verbena, Large-fruited Abronia macrocarpa

Sandwort, Bear Valley Arenaria ursina

Sandwort, Cumberland Arenaria cumberlandensis

Sandwort, Marsh Arenaria paludicola

Sanicula mariversa (ncn) Sanicula mariversa

Sanicula purpurea (ncn) Sanicula purpurea

Sawfish, Smalltooth Pristis pectinata

Schiedea haleakalensis (ncn) Schiedea haleakalensis

Schiedea helleri (ncn) Schiedea helleri

Schiedea hookeri (ncn) Schiedea hookeri

Schiedea kaalae (ncn) Schiedea kaalae

Schiedea kauaiensis (ncn) Schiedea kauaiensis

Schiedea lydgatei (ncn) Schiedea lydgatei

Schiedea membranacea (ncn) Schiedea membranacea

Schiedea nuttallii (ncn) Schiedea nuttallii

Schiedea sarmentosa (ncn) Schiedea sarmentosa

Schiedea spergulina var. leiopoda (ncn) Schiedea spergulina var. leiopoda

Schiedea spergulina var. spergulina (ncn) Schiedea spergulina var. spergulina

Schiedea verticillata (ncn) Schiedea verticillata

Schiedea, Diamond Head (Schiedea adamantis) Schiedea adamantis

Schoepfia arenaria (ncn) Schoepfia arenaria

Scrub-Jay, Florida Aphelocoma coerulescens

Sculpin, Pygmy Cottus paulus (=pygmaeus)

Sea turtle, green Chelonia mydas

Sea turtle, hawksbill Eretmochelys imbricata

Sea turtle, Kemp's ridley Lepidochelys kempii

Sea turtle, leatherback Dermochelys coriacea

Sea turtle, loggerhead Caretta caretta

Sea turtle, olive ridley Lepidochelys olivacea

Sea-blite, California Suaeda californica

Sheepnose mussel Plethobasus cyphyus

Shiner, Arkansas River Notropis girardi

Shiner, Beautiful Cyprinella formosa

Shiner, Blue Cyprinella caerulea

Shiner, Cahaba Notropis cahabae

Shiner, Cape Fear Notropis mekistocholas

Shiner, Palezone Notropis albizonatus

Shiner, Pecos Bluntnose Notropis simus pecosensis

Shiner, Topeka Notropis topeka (=tristis)

Shrike, San Clemente Loggerhead Lanius ludovicianus mearnsi

Shrimp, Alabama Cave Palaemonias alabamae

Shrimp, California Freshwater Syncaris pacifica
198

Common and Scientific Name

Shrimp, Kentucky Cave Palaemonias ganteri

Shrimp, Squirrel Chimney Cave Palaemonetes cummingi

Silene alexandri (ncn) Silene alexandri

Silene hawaiiensis (ncn) Silene hawaiiensis

Silene lanceolata (ncn) Silene lanceolata

Silene perlmanii (ncn) Silene perlmanii

Silverside, Waccamaw Menidia extensa

Silversword, Haleakala ('Ahinahina) Argyroxiphium sandwicense ssp. macrocephalum

Silversword, Ka'u (Argyroxiphium kauense) Argyroxiphium kauense

Silversword, Mauna Kea ('Ahinahina) Argyroxiphium sandwicense ssp. sandwicense

Skink, Blue-tailed Mole Eumeces egregius lividus

Skink, Sand Neoseps reynoldsi

Skipper, Carson Wandering Pseudocopaeodes eunus obscurus

Skipper, Laguna Mountain Pyrgus ruralis lagunae

Skipper, Pawnee Montane Hesperia leonardus montana

Skullcap, Florida Scutellaria floridana

Skullcap, Large-flowered Scutellaria montana

Slabshell, Chipola Elliptio chipolaensis

Smelt, Delta Hypomesus transpacificus

Snail, Armored Pyrgulopsis (=Marstonia) pachyta

Snail, Bliss Rapids Taylorconcha serpenticola

Snail, Chittenango Ovate Amber Succinea chittenangoensis

Snail, Flat-spired Three-toothed Triodopsis platysayoides

Snail, Iowa Pleistocene Discus macclintocki

Snail, Lioplax Cylindrical Lioplax cyclostomaformis

Snail, Morro Shoulderband Helminthoglypta walkeriana

Snail, Noonday Mesodon clarki nantahala

Snail, O'ahu Tree (Achatinella abbreviata) Achatinella abbreviata

Snail, O'ahu Tree (Achatinella apexfulva) Achatinella apexfulva

Snail, O'ahu Tree (Achatinella bellula) Achatinella bellula

Snail, O'ahu Tree (Achatinella buddii) Achatinella buddii

Snail, O'ahu Tree (Achatinella bulimoides) Achatinella bulimoides

Snail, O'ahu Tree (Achatinella byronii) Achatinella byronii

Snail, O'ahu Tree (Achatinella caesia) Achatinella caesia

Snail, O'ahu Tree (Achatinella casta) Achatinella casta

Snail, O'ahu Tree (Achatinella cestus) Achatinella cestus

Snail, O'ahu Tree (Achatinella concavospira) Achatinella concavospira

Snail, O'ahu Tree (Achatinella curta) Achatinella curta

Snail, O'ahu Tree (Achatinella decipiens) Achatinella decipiens

Snail, O'ahu Tree (Achatinella decora) Achatinella decora

Snail, O'ahu Tree (Achatinella dimorpha) Achatinella dimorpha

Snail, O'ahu Tree (Achatinella elegans) Achatinella elegans

Snail, O'ahu Tree (Achatinella fulgens) Achatinella fulgens

Snail, O'ahu Tree (Achatinella fuscobasis) Achatinella fuscobasis

Snail, O'ahu Tree (Achatinella juddii) Achatinella juddii

Snail, O'ahu Tree (Achatinella juncea) Achatinella juncea

Snail, O'ahu Tree (Achatinella lehuiensis) Achatinella lehuiensis

Snail, O'ahu Tree (Achatinella leucorraphe) Achatinella leucorraphe

Snail, O'ahu Tree (Achatinella lila) Achatinella lila

Snail, O'ahu Tree (Achatinella livida) Achatinella livida

Snail, O'ahu Tree (Achatinella lorata) Achatinella lorata

Snail, O'ahu Tree (Achatinella mustelina) Achatinella mustelina
199

Common and Scientific Name

Snail, O'ahu Tree (Achatinella papyracea) Achatinella papyracea

Snail, O'ahu Tree (Achatinella phaeozona) Achatinella phaeozona

Snail, O'ahu Tree (Achatinella pulcherrima) Achatinella pulcherrima

Snail, O'ahu Tree (Achatinella pupukanioe) Achatinella pupukanioe

Snail, O'ahu Tree (Achatinella rosea) Achatinella rosea

Snail, O'ahu Tree (Achatinella sowerbyana) Achatinella sowerbyana

Snail, O'ahu Tree (Achatinella spaldingi) Achatinella spaldingi

Snail, O'ahu Tree (Achatinella stewartii) Achatinella stewartii

Snail, O'ahu Tree (Achatinella swiftii) Achatinella swiftii

Snail, O'ahu Tree (Achatinella taeniolata) Achatinella taeniolata

Snail, O'ahu Tree (Achatinella thaanumi) Achatinella thaahumi

Snail, O'ahu Tree (Achatinella turgida) Achatinella turgida

Snail, O'ahu Tree (Achatinella valida) Achatinella valida

Snail, O'ahu Tree (Achatinella viridans) Achatinella viridans

Snail, O'ahu Tree (Achatinella vittata) Achatinella vittata

Snail, O'ahu Tree (Achatinella vulpina) Achatinella vulpina

Snail, Painted Snake Coiled Forest Anguispira picta

Snail, Pecos Assiminea Assiminea pecos

Snail, Snake River Physa Physa natricina

Snail, Stock Island Tree Orthalicus reses (not incl. nesodryas)

Snail, Tulotoma Tulotoma magnifica

Snail, Virginia Fringed Mountain Polygyriscus virginianus

Snake, Atlantic Salt Marsh Nerodia clarkii taeniata

Snake, Eastern Indigo Drymarchon corais couperi

Snake, Giant Garter Thamnophis gigas

Snake, Northern Copperbelly Water Nerodia erythrogaster neglecta

Snake, San Francisco Garter Thamnophis sirtalis tetrataenia

Snakeroot Eryngium cuneifolium

Sneezeweed, Virginia Helenium virginicum

Snowbells, Texas Styrax texanus

Southern Kidneyshell Ptychobranchus jonesi

Southern Sandshell Hamiota australis

Sparrow, Cape Sable Seaside Ammodramus maritimus mirabilis

Sparrow, Florida Grasshopper Ammodramus savannarum floridanus

Sparrow, San Clemente Sage Amphispiza belli clementeae

Spectaclecase mussel Cumberlandia monodonta

Spermolepis hawaiiensis (ncn) Spermolepis hawaiiensis

Spider, Government Canyon Bat Cave Neoleptoneta microps

Spider, Kauai Cave Wolf Adelocosa anops

Spider, Spruce-fir Moss Microhexura montivaga

Spider, Tooth Cave Leptoneta myopica

Spikedace Meda fulgida

Spinedace, Big Spring Lepidomeda mollispinis pratensis

Spinedace, Little Colorado Lepidomeda vittata

Spinedace, White River Lepidomeda albivallis

Spineflower, Ben Lomond Chorizanthe pungens var. hartwegiana

Spineflower, Howell's Chorizanthe howellii

Spineflower, Monterey Chorizanthe pungens var. pungens

Spineflower, Orcutt's Chorizanthe orcuttiana

Spineflower, Robust Chorizanthe robusta va r. robusta

Spineflower, Scotts Valley Chorizanthe robusta var. hartwegii

Spineflower, Slender-horned Dodecahema leptoceras
200

Common and Scientific Name

Spineflower, Sonoma Chorizanthe valida

Spinymussel, Altamaha Elliptio spinosa

Spinymussel, James River Pleurobema collina

Spinymussel, Tar River Elliptio steinstansana

Spiraea, Virginia Spiraea virginiana

Springfish, Hiko White River Crenichthys baileyi grandis

Springfish, Railroad Valley Crenichthys nevadae

Springfish, White River Crenichthys baileyi baileyi

Springsnail, Alamosa Tryonia alamosae

Springsnail, Bruneau Hot Pyrgulopsis bruneauensis

Springsnail, Chupadera Pyrgulopsis chupaderae

Springsnail, Koster's Juturnia kosteri

Springsnail, Roswell Pyrgulopsis roswellensis

Springsnail, San Bernardino Pyrgulopsis bernardina

Springsnail, Socorro Pyrgulopsis neomexicana

Springsnail, Three Forks Pyrgulopsis trivialis

Spurge, Deltoid Chamaesyce deltoidea ssp. deltoidea

Spurge, Garber's Chamaesyce garberi

Spurge, Hoover's Chamaesyce hooveri

Spurge, Telephus Euphorbia telephioides

Squawfish, Colorado Ptychocheilus lucius

Starling, Ponape Mountain Aplonis pelzelni

Steelhead Oncorhynchus (=Salmo) mykiss

Stenogyne angustifolia (ncn) Stenogyne angustifolia var. angustifolia

Stenogyne bifida (ncn) Stenogyne bifida

Stenogyne campanulata (ncn) Stenogyne campanulata

Stenogyne kanehoana (ncn) Stenogyne kanehoana

Stickleback, Unarmored Threespine Gasterosteus aculeatus williamsoni

Stickseed, Showy Hackelia venusta

Stickyseed, Baker's Blennosperma bakeri

Stilt, Hawaiian (=Ae'o) Himantopus mexicanus knudseni

Stirrupshell Quadrula stapes

Stonecrop, Lake County Parvisedum leiocarpum

Stork, Wood Mycteria americana

Sturgeon, Alabama Scaphirhynchus suttkusi

Sturgeon, Gulf Acipenser oxyrinchus desotoi

Sturgeon, North American green Acipenser medirostris

Sturgeon, Pallid Scaphirhynchus albus

Sturgeon, Shortnose Acipenser brevirostrum

Sturgeon, Shovelnose Scaphirhynchus platorynchus

Sturgeon, White Acipenser transmontanus

Sucker, June Chasmistes liorus

Sucker, Lost River Deltistes luxatus

Sucker, Modoc Catostomus microps

Sucker, Razorback Xyrauchen texanus

Sucker, Santa Ana Catostomus santaanae

Sucker, Shortnose Chasmistes brevirostris

Sucker, Warner Catostomus warnerensis

Sumac, Michaux's Rhus michauxii

Sunflower, Pecos Helianthus paradoxus

Sunflower, San Mateo Woolly Eriophyllum latilobum

Sunflower, Schweinitz's Helianthus schweinitzii
201

Common and Scientific Name

Sunray, Ash Meadows Enceliopsis nudicaulis var. corrugata

Swiftlet, Mariana Gray (=Vanikoro) Aerodramus vanikorensis bartschi

Tadpole Shrimp, Vernal Pool Lepidurus packardi

Tapered Pigtoe Fusconaia burkei

Taraxacum, California Taraxacum californicum

Tarplant, Gaviota Deinandra increscens ssp. villosa

Tarplant, Otay Deinandra (=Hemizonia) conjugens

Tarplant, Santa Cruz Holocarpha macradenia

Tectaria Estremerana Tectaria estremerana

Tern, California Least Sterna antillarum browni

Tern, Interior (population) Least Sterna antillarum

Tern, Roseate Sterna dougallii dougallii

Ternstroemia subsessilis (ncn) Ternstroemia subsessilis

Tetramolopium arenarium (ncn) Tetramolopium arenarium

Tetramolopium capillare (ncn) Tetramolopium capillare

Tetramolopium filiforme (ncn) Tetramolopium filiforme

Tetramolopium lepidotum ssp. lepidotum (ncn) Tetramolopium lepidotum ssp. lepidotum

Tetramolopium remyi (ncn) Tetramolopium remyi

Tetramolopium rockii (ncn) Tetramolopium rockii

Thelypody, Howell's Spectacular Thelypodium howellii spectabilis

Thistle, Chorro creek Bog Cirsium fontinale var. obispoense

Thistle, Fountain Cirsium fontinale var. fontinale

Thistle, La Graciosa Cirsium loncholepis

Thistle, Pitcher's Cirsium pitcher

Thistle, Sacramento Mountains Cirsium vinaceum

Thistle, Suisun Cirsium hydrophilum var. hydrophilum

Thornmint, San Diego Acanthomintha ilicifolia

Thornmint, San Mateo Acanthomintha obovata ssp. duttonii

Thrush, Large Kauai Myadestes myadestinus

Thrush, Molokai (Oloma'o) Myadestes lanaiensis rutha

Thrush, Small Kauai (Puaiohi) Myadestes palmeri

Toad, Arroyo Southwestern Bufo californicus (=microscaphus)

Toad, Houston Bufo houstonensis

Toad, Wyoming Bufo baxteri (=hemiophrys)

Topminnow, Gila (Yaqui) Poeciliopsis occidentalis

Torreya, Florida Torreya taxifolia

Tortoise, Desert Gopherus agassizi

Tortoise, Gopher Gopherus polyphemus

Towhee, Inyo Brown Pipilo crissalis eremophilus

Townsendia, Last Chance Townsendia aprica

Tree Fern, Elfin Cyathea dryopteroides

Trematolobelia singularis (ncn) Trematolobelia singularis

Trout, Apache Oncorhynchus apache

Trout, Bull Salvelinus confluentus

Trout, Gila Oncorhynchus gilae

Trout, Greenback Cutthroat Oncorhynchus clarki stomias

Trout, Lahontan Cutthroat Oncorhynchus clarki henshawi

Trout, Little Kern Golden Oncorhynchus aguabonita whitei

Trout, Paiute Cutthroat Oncorhynchus clarki seleniris

Tuctoria, Green's Tuctoria greenei

Turtle, Alabama Red-bellied Pseudemys alabamensis

Turtle, Bog Clemmys muhlenbergii
202

Common and Scientific Name

Turtle, Flattened Musk Sternotherus depressus

Turtle, Plymouth Red-bellied Pseudemys rubriventris bangsi

Turtle, Ringed Map Graptemys oculifera

Turtle, Yellow-blotched Map Graptemys flavimaculata

Twinpod, Dudley Bluffs Physaria obcordata

Uhiuhi (Caesalpinia kavaiensis) Caesalpinia kavaiense

Ulihi (Phyllostegia glabra var. lanaiensis) Phyllostegia glabra var. lanaiensis

Umbel, Huachuca Water Lilaeopsis schaffneriana var. recurva

Uvillo Eugenia haematocarpa

Vernonia Proctorii (ncn) Vernonia proctorii

Vervain, California Verbena californica

Vetch, Hawaiian (Vicia menziesii) Vicia menziesii

Vigna o-wahuensis (ncn) Vigna o-wahuensis

Viola helenae (ncn) Viola helenae

Viola lanaiensis (ncn) Viola lanaiensis

Viola oahuensis (ncn) Viola oahuensis

Vireo, Black-capped Vireo atricapilla

Vireo, Least Bell's Vireo bellii pusillus

Wahane (Pritchardia aylmer-robinsonii) Pritchardia aylmer-robinsonii

Wahine Noho Kula (Isodendrion pyrifolium) Isodendrion pyrifolium

Wallflower, Ben Lomond Erysimum teretifolium

Wallflower, Contra Costa Erysimum capitatum var. angustatum

Wallflower, Menzie's Erysimum menziesii

Warbler (=Wood), Golden-cheeked Dendroica chrysoparia

Warbler (=Wood), Kirtland's Dendroica kirtlandii

Warbler, Bachman's Vermivora bachmanii

Warbler, nightingale reed (old world warbler) Acrocephalus luscinia

Warea, Wide-leaf Warea amplexifolia

Watercress, Gambel's Rorippa gambellii

Water-willow, Cooley's Justicia cooleyi

Wawae'Iole (Phlegmariurus (=Huperzia) mannii) Huperzia mannii

Wawae'Iole (Phlegmariurus (=Lycopodium) nutans) Lycopodium (=Phlegmariurus) nutans

Whale, Blue Balaenoptera musculus

Whale, Bowhead Balaena mysticetus

Whale, North Pacific right Eubalaena japonica

Whipsnake (=Striped Racer), Alameda Masticophis lateralis euryxanthus

White-eye, Bridled (Nossa) Zosterops conspicillatus conspicillatus

White-eye, Ponape greater Rukia longirostra

White-eye, Rota Bridled Zosterops rotensis

Whitlow-wort, Papery Paronychia chartacea

Wild-buckwheat, Clay-loving Eriogonum pelinophilum

Wild-buckwheat, Gypsum Eriogonum gypsophilum

Wings, Pigeon Clitoria fragrans

Wire-lettuce, Malheur Stephanomeria malheurensis

Wireweed Polygonella basiramia

Woodland-star, San Clemente Island Lithophragma maximum

Woodpecker, Ivory-billed Campephilus principalis

Woodpecker, Red-cockaded Picoides borealis

Woodrat, Key Largo Neotoma floridana smalli

Woolly-star, Santa Ana River Eriastrum densifolium ssp. sanctorum

Woolly-threads, San Joaquin Monolopia (=Lembertia) congdonii

Woundfin Plagopterus argentissimus
203

Common and Scientific Name

Xylosma crenatum (ncn) Xylosma crenatum

Yellowcheek darter Etheostoma moorei

Yellowhead, Desert Yermo xanthocephalus

Yerba Santa, Lompoc Eriodictyon capitatum

Ziziphus, Florida Ziziphus celata

Table J-2. “No Effects” (Direct Effects Only) Determination for Listed Species Within 

Geographical Range of Quizalofop-P-Ethyl Uses, Based on Species Ecology and Biology

Common and Scientific Name Location Taxon Basis for “No Effects”

Bat, Lesser 

(=Sanborn's) 

Long-nosed

Leptonycteris 

curasoae 

yerbabuenae Arizona, New Mexico Mammal

Diet is seeds.1 This dietary item does 

not produce EECs that yield RQs 

above the LOC.

Gray Wolf Canis lupus

Michigan, Nebraska, 

Nevada, New Mexico, 

North Dakota, 

Washington, Wisconsin Mammal

Diet is mammals and fish.2 Not 

likely to be exposed to residues 

through diet.

Jaguar Panthera onca

Arizona, California, 

New Mexico Mammal

Diet is fish, mammals, reptiles, 

birds.3 Unlikely to be exposed to 

residues through diet route.

Jaguarundi, 

Gulf Coast

Herpailurus (=Felis) 

yagouaroundi 

cacomitli Texas Mammal

Diet is mammals, birds, and reptiles.4 

Unlikely to be exposed to residues 

through diet route.

Jaguarundi, 

Sinaloan

Herpailurus (=Felis) 

yagouaroundi tolteca Arizona Mammal

Diet is amphibian, fish, birds, seeds, 

mammals, and reptiles.5 Unlikely to 

be exposed to residues through diet 

route.

Killer whale, 

Southern 

Resident DPS Orcinus orca Washington Mammal

Diet is fish, mammals, and aquatic 

invertebrates.6 Not likely to be 

exposed to residues through diet.

Lynx, Canada Lynx canadensis

Colorado, Idaho, 

Maine, Michigan, 

Minnesota, Montana, 

New Hampshire, 

Oregon, Utah, 

Vermont, Washington, 

Wisconsin, Wyoming Mammal

Diet is mammals, carrion, and fish.7 

Unlikely to be exposed to residues 

through diet route.
204

Common and Scientific Name Location Taxon Basis for “No Effects”

Manatee, West 

Indian Trichechus manatus

Alabama, Florida, 

Georgia, Louisiana, 

Mississippi, North 

Carolina, Puerto Rico, 

South Carolina, Texas Mammal

Diet is aquatic plants.8 Unlikely to 

be exposed to residues through diet 

route.

Ocelot

Leopardus (=Felis) 

pardalis Arizona, Texas Mammal

Diet is mammals, birds, and reptiles.9 

Unlikely to be exposed to residues 

through diet route.

Otter, 

Southern Sea Enhydra lutris nereis California Mammal

Diet is aquatic invertebrates and 

fish.10 Unlikely to be exposed to 

residues through diet route.

Panther, 

Florida

Puma (=Felis) 

concolor coryi Arkansas, Florida Mammal

Diet is mammals and reptiles.11 

Unlikely to be exposed to residues 

through these food sources.

Seal, 

Guadalupe Fur

Arctocephalus 

townsendi California Mammal

Diet is aquatic invertebrates and 

fish.12 Unlikely to be exposed to 

residues through diet route.

Seal, Hawaiian 

Monk

Monachus 

schauinslandi Hawaii Mammal

Diet is aquatic invertebrates and 

fish.13 Unlikely to be exposed to 

residues through diet route.

Seal, spotted Phoca largha Alaska Mammal

Diet is aquatic invertebrates and 

fish.14 Unlikely to be exposed to 

residues through diet route.

Sea-lion, 

Steller Eumetopias jubatus California Mammal

Diet is aquatic invertebrates and fish, 

may also include some mammals and 

birds.15 Unlikely to be exposed to 

residues through diet route.

Squirrel, 

Mount 

Graham Red

Tamiasciurus 

hudsonicus 

grahamensis Arizona Mammal

Diet is carrion and seeds.16 Carrion 

is not likely to be a source of residue 

exposures. Seeds yielded EECs that 

produced RQs below the LOC.

Whale, beluga

Delphinapterus 

leucas Alaska Mammal

Diet is aquatic invertebrates and 

fish.17 Unlikely to be exposed to 

residues through diet route.

Whale, 

Finback

Balaenoptera 

physalus California Mammal

Diet is aquatic invertebrates and 

fish.18 Unlikely to be exposed to 

residues through diet route.
205

Common and Scientific Name Location Taxon Basis for “No Effects”

Whale, Gray Eschrichtius robustus

Alaska, California, 

Oregon, Washington Mammal

Diet is aquatic invertebrates.19 

Unlikely to be exposed to residues 

through diet route.

Whale, 

Humpback

Megaptera 

novaeangliae California, Georgia Mammal

Diet is aquatic invertebrates and 

fish.20 Unlikely to be exposed to 

residues through diet route.

Whale, North 

Atlantic right

Eubalaena glacialis 

(incl. australis) California, Georgia Mammal

Diet is aquatic invertebrates.21 

Unlikely to be exposed to residues 

through diet route.

Whale, Sei

Balaenoptera 

borealis California Mammal

Diet is aquatic invertebrates and 

fish.22 Unlikely to be exposed to 

residues through diet route.

Whale, Sperm

Physeter catodon 

(=macrocephalus) California Mammal

Diet is aquatic invertebrates and 

fish.23 Unlikely to be exposed to 

residues through diet route.

Wolf, Red Canis rufus

Kentucky, North 

Carolina Mammal

Diet is mammals.24 Unlikely to be 

exposed to residues through diet.

Guajon

Eleutherodactylus 

cooki Puerto Rico Amphibian

Lives in caves.25 Unlikely to be 

exposed to residues.

Amphipod, 

Kauai Cave

Spelaeorchestia 

koloana Hawaii Crustacean

Lives in caves.26 Unlikely to be 

exposed to residues.

1USFWS. 1994. Recovery plan for the lesser long-nosed bat.

2USFWS. 1982. Mexican wolf recovery plan.

2USFWS. 1987. Northern rocky mountain wolf recovery plan.

2USFWS. 1992. Recovery plan for the eastern timber wolf.

2USFWS. 2012. Gray wolf (Canis lupus).

3USFWS. 2010. Species profile for the jaguar.

4USFWS. 2001. Jaguarundi general species information.

5Arizona Game and Fish Department. 2004. Herpailurus yaguarondi tolteca. Unpublished abstract compiled and edited by the Heritage 

Data Management System.

6USNMFS. 2006. Designation of critical habitat for southern resident killer whale. Federal register. 71. No. 229.

7USFWS. 2012. Canada lynx (Lynx canadensis)

8USFWS. 2007. West indian manatee (Trichechus manatus) 5-year review: summary and evaluation.

8USFWS. 2001. Florida manatee (Trichechus manatus latirostris) recovery plan, third revision.

8USFWS. Recovery plan for the Puerto Rico population of the west indian (Antillean) manatee (Trichechus manatus manatus).

9USFWS. 2010. Ocelot (Leopardus pardalis) recovery plan, draft first revision.

10USFWS. 2003. Final revised recovery plan for the southern sea otter (Enhydra lutris nereis).

11USFWS. 2008. Third revision of the florida panther recovery plan.

12USNMFS. Species profile: Guadalupe fur seal. NOAA Fisheris Office of Protected Resources.

13USNMFS. 2007. Recovery plan for the Hawaiian monk seal (revision).

14USNMFS. 2010. Threatened status for the southern distinct population segment of the spotted seal. Federal Register. 75. No. 204.

15USNMFS. 2008. Recovery plan for the steller sea lion eastern and western distinct population segments (Eumetopias jubatus)

16USFWS. 2011. Draft mount graham red squirrel recovery plan, first revision. USFS.

17USNMFS. 2013. Species profile for the beluga whale. Office of Protected Resources, NOAA Fisheries. 

18USNMFS. 2010. Recovery plan for the fin whale (Baalaenoptera physalus).

19USNMFS. 1991. Endangered fish and wildlife, gray whale. Federal Register. 56. No. 226.

20USNMFS. 1991. Final recovery plan for the humpback whale (Megaptera novaeangliae). Prepared by the Humpback Whale 

Recovery Team for the National Marine Fisheries Service, Silver Spring, MD.

21USFWS. 2010. North Atlantic right whale recovery plan.

22USNMFS. 2012. Sei whale (Balaenoptera borealis). NOAA Fisheries.
206

Common and Scientific Name Location Taxon Basis for “No Effects”

23USNMFS. 2012. Sperm whales (Physeter macrocephalus). NOAA Fisheries.

24USFWS. 1995. FR Notice of critical habitat. Federal Register. 60. No. 71.

24Paradiso, J. L. and R. M. Nowak. 1972. Canus rufus. The American Society of Mammologists, Mammalian Species.

25USFWS. 2004. Recovery plan for the guajon or Puerto Rican demon (Eleutherodactylus cooki).

26USFWS. 2006. Final recovery plan for the Kaua’I cave arthropods: the Kaua’I cave wolf spider (Adelocosa anops) and the Kaua’I 

cave amphipod (Spelaeorchestia koloana).

Table J-3. Listed Species Within Geographical Range of Quizalofop-P-Ethyl Uses that 

Require Additional Information for Effects Calls

Common and Scientific Name Habit Location Taxon

Coqui, Golden

Eleutherodactylus 

jasperi

Terrestrial, 

Freshwater Puerto Rico Amphibian

Llanero coqui

Eleutherodactylus 

juanariveroi Terrestrial Puerto Rico Amphibian

Toad, Puerto 

Rican Crested Peltophryne lemur

Terrestrial, 

Freshwater Puerto Rico Amphibian

Snail, Newcomb's Erinna newcombi Freshwater Hawaii Gastropod

Bat, Gray Myotis grisescens

Terrestrial, 

Subterraneous

Alabama, Arkansas, 

Florida, Georgia, 

Illinois, Indiana, 

Kansas, Kentucky, 

Mississippi, Missouri, 

North Carolina, 

Oklahoma, Tennessee, 

Virginia Mammal

Bat, Hawaiian 

Hoary

Lasiurus cinereus 

semotus

Terrestrial, 

Subterraneous Hawaii Mammal

Bat, Indiana Myotis sodalis

Terrestrial, 

Subterraneous

Alabama, Arkansas, 

Connecticut, Florida, 

Georgia, Illinois, 

Indiana, Iowa, 

Kentucky, Maryland, 

Massachusetts, 

Michigan, Mississippi, 

Missouri, New Jersey, 

New York, North 

Carolina, Ohio, 

Oklahoma, 

Pennsylvania, 

Tennessee, Vermont, 

Virginia, West Virginia Mammal

Bat, Mexican 

Long-nosed

Leptonycteris 

nivalis

Terrestrial, 

Subterraneous New Mexico, Texas Mammal

Bat, Ozark Bigeared

Corynorhinus 

(=Plecotus) 

townsendii ingens

Terrestrial, 

Subterraneous

Arkansas, Oklahoma, 

Virginia Mammal
207

Common and Scientific Name Habit Location Taxon

Bat, Virginia Bigeared

Corynorhinus 

(=Plecotus) 

townsendii 

virginianus

Terrestrial, 

Subterraneous

Kentucky, North 

Carolina, West Virginia Mammal

Bear, Grizzly

Ursus arctos 

horribilis Terrestrial

Idaho, Montana, 

Washington Mammal

Bear, Louisiana 

Black

Ursus americanus 

luteolus Terrestrial

Louisiana, Mississippi, 

Texas Mammal

Bison, Wood

Bison bison 

athabascae Terrestrial Alaska Mammal

Caribou, 

Woodland

Rangifer tarandus 

caribou Terrestrial Idaho, Washington Mammal

Deer, Columbian 

White-tailed

Odocoileus 

virginianus 

leucurus Terrestrial Oregon, Washington Mammal

Ferret, Blackfooted Mustela nigripes Terrestrial

Arizona, Colorado, 

Kansas, Montana, 

Nebraska, New 

Mexico, North Dakota, 

South Dakota, Utah, 

Wyoming Mammal

Fox, San Joaquin 

Kit

Vulpes macrotis 

mutica Terrestrial California Mammal

Fox, San Miguel 

Island

Urocyon littoralis 

littoralis Terrestrial California Mammal

Fox, Santa 

Catalina Island

Urocyon littoralis 

catalinae Terrestrial California Mammal

Fox, Santa Cruz 

Island

Urocyon littoralis 

santacruzae Terrestrial California Mammal

Fox, Santa Rosa 

Island

Urocyon littoralis 

santarosae Terrestrial California Mammal

Kangaroo Rat, 

Fresno

Dipodomys 

nitratoides exilis Terrestrial California Mammal

Kangaroo Rat, 

Giant Dipodomys ingens Terrestrial California Mammal

Kangaroo Rat, 

Morro Bay

Dipodomys 

heermanni 

morroensis Terrestrial California Mammal

Kangaroo Rat, 

San Bernardino 

Merriam's

Dipodomys 

merriami parvus Terrestrial California Mammal

Kangaroo Rat, 

Stephens'

Dipodomys 

stephensi (incl. D. 

cascus) Terrestrial California Mammal

Kangaroo Rat, 

Tipton

Dipodomys 

nitratoides 

nitratoides Terrestrial California Mammal

Mountain Beaver, 

Point Arena

Aplodontia rufa 

nigra

Terrestrial, 

Freshwater California Mammal
208

Common and Scientific Name Habit Location Taxon

Mouse, Alabama 

Beach

Peromyscus 

polionotus 

ammobates

Terrestrial, 

Coastal Alabama Mammal

Mouse, Anastasia 

Island Beach

Peromyscus 

polionotus phasma

Terrestrial, 

Coastal Florida Mammal

Mouse, 

Choctawhatchee 

Beach

Peromyscus 

polionotus 

allophrys

Terrestrial, 

Coastal Florida Mammal

Mouse, Pacific 

Pocket

Perognathus 

longimembris 

pacificus Terrestrial California Mammal

Mouse, Perdido 

Key Beach

Peromyscus 

polionotus 

trissyllepsis

Terrestrial, 

Coastal Alabama, Florida Mammal

Mouse, Preble's 

Meadow Jumping

Zapus hudsonius 

preblei Terrestrial Colorado, Wyoming Mammal

Mouse, Salt 

Marsh Harvest

Reithrodontomys 

raviventris Terrestrial California Mammal

Mouse, 

Southeastern 

Beach

Peromyscus 

polionotus 

niveiventris

Terrestrial, 

Coastal Florida Mammal

Mouse, St. 

Andrew Beach

Peromyscus 

polionotus 

peninsularis

Terrestrial, 

Coastal Florida Mammal

Prairie Dog, Utah Cynomys parvidens

Terrestrial, 

Subterraneous Utah Mammal

Pronghorn, 

Sonoran

Antilocapra 

americana 

sonoriensis Terrestrial Arizona Mammal

Puma (=Cougar), 

Eastern

Puma (=Felis) 

concolor (all subsp. 

except coryi) Terrestrial

Florida, North 

Carolina, Rhode Island Mammal

Rabbit, Pygmy

Brachylagus 

idahoensis Terrestrial Washington Mammal

Rabbit, Riparian 

Brush

Sylvilagus 

bachmani riparius Terrestrial California Mammal

Sheep, Peninsular 

Bighorn

Ovis canadensis 

nelsoni Terrestrial California Mammal

Sheep, Sierra 

Nevada Bighorn

Ovis canadensis 

sierrae Terrestrial California Mammal

Shrew, Buena 

Vista Lake Ornate

Sorex ornatus 

relictus Terrestrial California Mammal

Squirrel, Carolina 

Northern Flying

Glaucomys 

sabrinus coloratus Terrestrial

North Carolina, 

Tennesee, Virginia Mammal

Squirrel, 

Delmarva 

Peninsula Fox

Sciurus niger 

cinereus Terrestrial

Delaware, Maryland, 

Virginia Mammal

Squirrel, Northern 

Idaho Ground

Spermophilus 

brunneus brunneus Terrestrial Idaho Mammal
209

Common and Scientific Name Habit Location Taxon

Squirrel, Virginia 

Northern Flying

Glaucomys 

sabrinus fuscus Terrestrial Virginia Mammal

Vole, Amargosa

Microtus 

californicus 

scirpensis Terrestrial California Mammal

Vole, Florida Salt 

Marsh

Microtus 

pennsylvanicus 

dukecampbelli

Terrestrial, 

Brackish Florida Mammal

Vole, Hualapai 

Mexican

Microtus mexicanus 

hualpaiensis Terrestrial Arizona Mammal

Woodrat, Riparian

Neotoma fuscipes 

riparia Terrestrial California Mammal

Alopecurus, 

Sonoma

Alopecurus 

aequalis var. 

sonomensis

Unattributed 

Wetland Status California Monocot

Amole, Cammatta 

Canyon

Chlorogalum 

purpureum var. 

reductum

Unattributed 

Wetland Status California Monocot

Amole, Purple

Chlorogalum 

purpureum var. 

purpureum

Unattributed 

Wetland Status California Monocot

Aristida chaseae 

(ncn) Aristida chaseae

Unattributed 

Wetland Status Puerto Rico Monocot

Arrowhead, 

Bunched

Sagittaria 

fasciculata Wetland

North Carolina, South 

Carolina Monocot

Beaked-rush, 

Knieskern's

Rhynchospora 

knieskernii Wetland New Jersey Monocot

Beargrass, 

Britton's Nolina brittoniana

Unattributed 

Wetland Status Florida Monocot

Beauty, Harper's Harperocallis flava Wetland Florida Monocot

Bluegrass, 

Hawaiian Poa sandvicensis Wetland Hawaii Monocot

Bluegrass, Mann's 

(Poa mannii) Poa mannii Wetland Hawaii Monocot

Bluegrass, Napa Poa napensis Wetland California Monocot

Bluegrass, San 

Bernardino Poa atropurpurea Wetland California Monocot

Brodiaea, Chinese 

Camp Brodiaea pallida Wetland California Monocot

Brodiaea, Threadleaved Brodiaea filifolia Wetland California Monocot

Bulrush, 

Northeastern 

(=Barbed Bristle)

Scirpus 

ancistrochaetus Wetland

Alabama, Maryland, 

Massachusetts, New 

Hampshire, 

Pennsylvania, 

Vermont, Virginia, 

West Virginia Monocot
210

Common and Scientific Name Habit Location Taxon

Cranichis Ricartii Cranichis ricartii

Unattributed 

Wetland Status Puerto Rico Monocot

Fritillary, 

Gentner's Fritillaria gentneri

Unattributed 

Wetland Status Oregon Monocot

Grass, California 

Orcutt Orcuttia californica Wetland California Monocot

Grass, Colusa

Neostapfia 

colusana Wetland California Monocot

Grass, Eureka 

Dune

Swallenia 

alexandrae

Unattributed 

Wetland Status California Monocot

Grass, Fosberg's 

Love Eragrostis fosbergii

Unattributed 

Wetland Status Hawaii Monocot

Grass, San 

Joaquin Valley 

Orcutt Orcuttia inaequalis Wetland California Monocot

Grass, Solano Tuctoria mucronata Wetland California Monocot

Grass, Tennessee 

Yellow-eyed Xyris tennesseensis Wetland

Alabama, Georgia, 

Tennessee Monocot

Hala Pepe 

(Pleomele 

hawaiiensis)

Pleomele 

hawaiiensis

Unattributed 

Wetland Status Hawaii Monocot

Hilo Ischaemum 

(Ischaemum 

byrone) Ischaemum byrone Wetland Hawaii Monocot

Iris, Dwarf Lake Iris lacustris Wetland Michigan, Wisconsin Monocot

Irisette, White

Sisyrinchium 

dichotomum

Unattributed 

Wetland Status

North Carolina, South 

Carolina Monocot

Kamanomano 

(Cenchrus 

agrimonioides)

Cenchrus 

agrimonioides

Unattributed 

Wetland Status Hawaii Monocot

Ladies'-tresses, 

Canelo Hills

Spiranthes 

delitescens Wetland Arizona Monocot

Ladies'-tresses, 

Navasota Spiranthes parksii

Unattributed 

Wetland Status Texas Monocot

Ladies'-tresses, 

Ute

Spiranthes 

diluvialis Wetland

Arkansas, Colorado, 

Idaho, Montana, 

Nebraska, Nevada, 

Utah, Washington, 

Wyoming Monocot

Lau'ehu (Panicum 

niihauense)

Panicum 

niihauense

Unattributed 

Wetland Status Hawaii Monocot

Lepanthes 

eltorensis (ncn)

Lepanthes 

eltoroensis

Unattributed 

Wetland Status Puerto Rico Monocot

Lily, Minnesota 

Trout

Erythronium 

propullans

Unattributed 

Wetland Status Minnesota Monocot

Lily, Pitkin Marsh

Lilium pardalinum 

ssp. pitkinense

Unattributed 

Wetland Status California Monocot
211

Common and Scientific Name Habit Location Taxon

Lily, Tiburon 

Mariposa

Calochortus 

tiburonensis

Unattributed 

Wetland Status California Monocot

Lily, Western Lilium occidentale Wetland California, Oregon Monocot

lo`ulu Pritchardia hardyi Wetland Hawaii Monocot

Lo`ulu 

(Pritchardia 

affinis) Pritchardia affinis Wetland Hawaii Monocot

Lo`ulu 

(Pritchardia 

kaalae) Pritchardia kaalae Wetland Hawaii Monocot

Lo`ulu 

(Pritchardia 

napaliensis)

Pritchardia 

napaliensis

Unattributed 

Wetland Status Hawaii Monocot

Lo`ulu 

(Pritchardia 

schattaueri)

Pritchardia 

schattaueri

Unattributed 

Wetland Status Hawaii Monocot

Lo`ulu 

(Pritchardia 

viscosa) Pritchardia viscosa Wetland Hawaii Monocot

Manaca, palma de

Calyptronoma 

rivalis Wetland Puerto Rico Monocot

Mariscus fauriei 

(ncn) Mariscus fauriei

Unattributed 

Wetland Status Hawaii Monocot

Mariscus 

pennatiformis 

(ncn)

Mariscus 

pennatiformis

Unattributed 

Wetland Status Hawaii Monocot

Onion, Munz's Allium munzii

Unattributed 

Wetland Status California Monocot

Orchid, Eastern 

Prairie Fringed

Platanthera 

leucophaea Wetland

Illinois, Indiana, Iowa, 

Maine, Michigan, New 

York, Ohio, Oklahoma, 

Virginia, Wisconsin Monocot

Orchid, Western 

Prairie Fringed

Platanthera 

praeclara

Unattributed 

Wetland Status

Iowa, Kansas, 

Minnesota, Missouri, 

Nebraska, North 

Dakota, Oklahoma, 

South Dakota, 

Wyoming Monocot

Pa'iniu Astelia waialealae Wetland Hawaii Monocot

Panicgrass, 

Carter's (Panicum 

fauriei var.carteri)

Panicum fauriei 

var. carteri

Unattributed 

Wetland Status Hawaii Monocot

Pelos del Diablo

Aristida 

portoricensis

Unattributed 

Wetland Status Puerto Rico Monocot

Pink, Swamp Helonias bullata Wetland

Georgia, Maryland, 

New Jersey, North 

Carolina, South 

Carolina, Virginia Monocot

Piperia, Yadon's Piperia yadonii

Unattributed 

Wetland Status California Monocot
212

Common and Scientific Name Habit Location Taxon

Platanthera 

holochila (ncn)

Platanthera 

holochila Wetland Hawaii Monocot

Poa siphonoglossa 

(ncn) Poa siphonoglossa Wetland Hawaii Monocot

Pogonia, Small 

Whorled Isotria medeoloides Wetland

Connecticut, Delaware, 

Georgia, Illinois, 

Maine, Massachusetts, 

Michigan, New 

Hampshire, New 

Jersey, New York, 

North Carolina, Ohio, 

Pennsylvania, Rhode 

Island, South Carolina, 

Tennessee, Vermont, 

Virginia, West Virginia Monocot

Pu'uka'a (Cyperus 

trachysanthos)

Cyperus 

trachysanthos Wetland Hawaii Monocot

Seagrass, 

Johnson's Halophila johnsonii Wetland Florida Monocot

Sedge, Golden Carex lutea

Unattributed 

Wetland Status North Carolina Monocot

Sedge, Navajo Carex specuicola Wetland Arizona, Utah Monocot

Sedge, White Carex albida Wetland California Monocot

Trillium, 

Persistent Trillium persistens

Unattributed 

Wetland Status

Georgia, South 

Carolina Monocot

Trillium, Relict Trillium reliquum

Unattributed 

Wetland Status

Alabama, Georgia, 

South Carolina Monocot

Walnut, Nogal Juglans jamaicensis

Unattributed 

Wetland Status Puerto Rico Monocot

Water-plantain, 

Kral's

Sagittaria 

secundifolia Wetland Alabama, Georgia Monocot

Wild-rice, Texas Zizania texana Wetland Texas Monocot