2

potential risks associated with the use of quinoxyfen as well as uncertainties unique to the risk 

assessment. This document also identifies additional studies that would be beneficial to the 

conduct of the ecological risk assessment. Below is a summary of data needs and uncertainties.

• Based on the environmental fate properties of quinoxyfen, exposure of sediment-dwelling 

organisms is expected. Therefore, toxicity data on the standard set of benthic 

invertebrates are needed.

• For estuarine/marine invertebrates, the potential for chronic risk concerns is uncertain 

because a no-observed-adverse-effects concentration (NOAEC) was not established (i.e., 

adverse effects were observed at all concentrations tested) during a life-cycle toxicity 

study with mysid shrimp (Americamysis bahia); therefore, additional chronic toxicity

data on this species are needed.

• There is uncertainty regarding the potential effects of quinoxyfen on larval (brood)

development of honey bees (Apis mellifera) and other terrestrial invertebrates, since acute 

toxicity data are only available for young adult honey bees but not for developing brood.

EFED is now recommending that a larval toxicity test be performed as part of the new 

tiered screening approach for assessing risk to bees.

2. Introduction

Quinoxyfen is a systemic fungicide and belongs to the phenoxyquinoline class of chemicals. 

Quinoxyfen’s fungicidal activity is reported to be specific to powdery mildews (e.g., Erysiphe 

cichoracearum, Sphaerothecafulginea, Podosphaera clandestina) (USEPA, 2003b). Based on 

information provided by the registrant, quinoxyfen appears to work with a novel mode of action 

which has attributes of a multi-site fungicide and which differs from that of either of the two 

primary classes of synthetic, single-site fungicides (demethylation inhibitors and strobilurins). 

The chemical’s main mode of action occurs at the cellular level and is through inhibition of 

primary appressorial formation (USEPA, 2003b; Wheeler et al. 2003). Quinoxyfen is formulated 

as emulsifiable and suspension concentrates and it is used as a ground and/or aerial spray 

application. The maximum single application rate for quinoxyfen is on stone fruits at 0.130

pounds of active ingredient per acre (lbs a.i./A). 

EFED evaluated the most recent ecological risk assessments for quinoxyfen in association with 

updated toxicity, exposure, and usage information to determine if sufficient data are available 

and if additional data are needed to support registration review. Recent risk assessments include 

a 2012 assessment for the use of quinoxyfen on fruiting vegetables group 8-10B, small fruit vine 

climbing (except fuzzy kiwifruit) subgroup 13-07F and low-growing berry subgroup 13-07G 

(USEPA, 2013c). In addition, EFED considered the latest Agency science policies and risk 

assessment methodologies. 

3. Use Characterization

Quinoxyfen is used as a ground (stone fruits, cherry, grape and hops) and/or aerial spray 

application (artichoke, head and leaf lettuce, melons, pepper, strawberry, gourds and pumpkin 

and winter squash). It is currently registered for use on artichoke, gourds, lettuce, melons, 
3

pepper, pumpkin, stone fruits, strawberry, winter squash, cherry, grapes and hops. The current 

maximum single application rate is 0.130 lbs a.i./A for stone fruits and the maximum annual 

application is 0.57 lbs a.i./A for cherries. During the 2007-2011 timeframe, on average 

approximately 33,000 pounds of quinoxyfen were applied in the U.S. annually to treat 372,000 

acres at an overall average application rate of 0.1 lbs. a.i./acre (USEPA 2013d). The top crops in 

terms of lbs a.i. applied during this period were wine grapes (52%), cherries (14%), table grapes 

(10%), raisin grapes (8%), strawberries (5%), peppers (3%), watermelons (3%), and cantaloupes 

(2%). The top crops in terms of total area treated were wine grapes (54%), cherries (12%), table 

grapes (11%), raisin grapes (8%), and strawberries (5%) Further details on the quinoxyfen usage

profile and history, based partially upon proprietary data sources, are provided in the BEAD 

Chemical Profile (USEPA 2013d).

The chemical profile produced by BEAD, lists the use patterns of maximum exposures for the 

current uses of quinoxyfen. EFED will use application scenarios that result in maximum 

exposure scenarios for a given use for the risk assessment. 

4. Conclusions from Previous Risk Assessments

The Agency has conducted multiple ecological risk assessments on quinoxyfen that serve as a 

basis for this problem formulation, including a reduced risk assessment (USEPA 2013c). The 

major conclusions and uncertainties described in previous risk assessments of quinoxyfen are 

bulleted below and are summarized in Table 1:

• There is the potential for adverse effects to Federally-listed threatened/endangered 

(hereafter referred to as “listed”) and non-listed mammals and estuarine/marine 

invertebrates on a chronic exposure basis. 

• For estuarine/marine invertebrates, the potential for chronic risk is uncertain because a 

definitive no-observed-adverse-effects concentration (NOAEC) was not established (i.e., 

adverse effects were observed at all concentrations tested) during a life-cycle toxicity 

study with mysid shrimp.

• There is uncertainty regarding the potential effects of quinoxyfen on larval development 

of honey bees and other terrestrial invertebrates, since acute toxicity data are only 

available for young adult honey bees but not for developing brood.

• Quinoxyfen is expected to bioaccumulate in the aquatic environment based on available 

environmental fate and bioconcentration studies. However, due to the low application 

rates and low mobility of quinoxyfen, previous risk estimates for birds or mammals that 

feed on aquatic prey contaminated with quinoxyfen were below Agency acute and 

chronic risk levels of concern (LOCs).

• Quinoxyfen is likely to persist in the terrestrial environment (half-lives of >102 days), but 

may be less persistent in the aquatic environment given that its anaerobic aquatic and 

aerobic aquatic metabolism half-lives ranged from 18 to 50 days (slightly to moderately

persistent). 

• In drinking water, quinoxyfen plus its degradate 2-oxo-quinoxyfen, are considered to be 

of human health concern due to its structural similarity to the parent. However, only 

quinoxyfen is currently considered to be of ecological concern since major degradates 
4

DCHQ and 2-oxo-quinoxyfen are considerably less toxic than the parent compounds to 

ecological receptors.

a. Ecological Risk Assessment 

The Agency has conducted multiple ecological risk assessments of quinoxyfen that serve as a 

basis for this scoping document, including a recent reduced risk assessment (USEPA 2013a) and 

recent new use ecological risk assessment (USEPA 2013c). The primary risk issues that have 

been identified have been for mammals on a chronic exposure basis. However, chronic risk has 

also been presumed for estuarine/marine invertebrates due to lack of definitive chronic toxicity 

data based on submitted studies. Potential risk issues identified in previous assessments are 

briefly summarized in Table 1.

Table 1. Summary of Potential Risk Issues Identified for Quinoxyfen in Previous 

Assessments

Birds Mammals Terr.

Plants

Terr.

Inverts Fish BCF Aquatic Inverts

Aquatic 

Plants

Groundwater 

Contamination Persistence Degradates of Concern

No Yes

(chronic) No NA No Yesa Yesb(chronic) Yesc No Yesd No

Yes = at least one LOC has been exceeded in previous assessments; No = LOCs have not been exceeded in previous 

assessments; NA = RQs have not been calculated previously.

a The BCF threshold was passed (above 5000X) however, the risk to bids and mammals that feed on contaminated 

food item is below LOCs. 

b Chronic risk to estuarine/marine invertebrates was assumed in previous risk assessments due to lack of definitive 

chronic toxicity data for mysid shrimp.

c Risk to aquatic plants was assumed in previous risk assessments due to lack of toxicity data on aquatic vascular 

plants; however, the most recent ecological risk assessment (EPA 2013c) did not find any risks of concern for 

aquatic plants based on recently submitted vascular aquatic plant toxicity data for Lemna gibba (MRID 48387901) d Not likely to persist in aquatic environment. However, in terrestrial environments, quinoxyfen is likely to persist, 

with half-lives of >102 days.

b. Drinking Water Exposure Assessments

The EFED conducted a drinking water assessment of quinoxyfen on April 23, 2013 (USEPA

2013b and USEPA 2008). The estimated drinking water concentrations (EDWCs) recommended 

for use in the (human) Health Effects Division’s dietary risk assessment were based on the 

cherry use (highest EDWCs of the agricultural uses). The acute and chronic EDWCs for surface 

water were 9.9 and 0.66 μg a.i./L (parts per billion; ppb), respectively and 0.003 μg a.i./L for 

groundwater. EDWCs represent concentrations of quinoxyfen plus its degradate 3-OH 

quinoxyfen (hereafter 2-oxo-quinoxyfen; USEPA 2010), which is considered to be of human 

health concern due to its structural similarity to the parent (USEPA 2003a).

c. Clean Water Act Programs

Quinoxyfen is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act. No Total Maximum Daily Load (TMDL) criteria 

have been developed for quinoxyfen. 1

 1 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885
5

 

5. Environmental Fate and Transport

Quinoxyfen is likely to persist in the terrestrial environment (half-lives of >102 days), but may 

be less persistent in the aquatic environment given that its anaerobic aquatic and aerobic aquatic 

metabolism half-lives ranged from 18 to 50 days (slightly to moderately persistent based on 

Goring et al. 1975). Quinoxyfen is expected to be relatively immobile in the environment, and is 

expected to readily partition to sediment (Koc=18339-75930 mL/g, FAO scale, 2000). Because of 

its propensity to sorb to sediment and its generally low solubility, quinoxyfen has low potential 

to leach to groundwater. However, quinoxyfen can reach surface waters through spray drift and 

runoff of sediment-bound residues (i.e., erosion). Despite its overall persistence, under ideal 

conditions (e.g. when the compound is present in an unsorbed state in clear, shallow surface 

water under favorable light conditions) the compound may rapidly photodegrade (t1/2<1 day). 

However, such photodegradation can only happen under particular conditions that are not likely 

to occur in most circumstances. A selection of environmental fate and transport properties of 

quinoxyfen is summarized Table 2. Based on its vapor pressure (1.5x 10-7 atm) quinoxyfen is 

not expected to volatilize. The chemical’s solubility in water exhibits pH dependence, with for 

example, the chemical being about three times more soluble at acidic than at neutral pHs (0.128 

mg/L at pH 5, 0.047 mg/L at pH 7 and 0.036 mg/L at pH 9). The variable solubility in water 

across pH values indicates that the compound exhibits acid-base behavior. 

Table 2. Chemical Properties and Environmental Fate Parameters of Quinoxyfen

Parameter Value Description Reference

Chemical 

Classification phenoxyquinoline

Product 

Chemistry

Molecular Formula C15H8Cl2FNO

PC Code 055459

Chemical Name 

(IUPAC)

5,7-dichloro-4-(pfluorophenoxy)quinoline

Chemical Name 

(CAS)

5,7-dichloro-4-(4-

fluorophenoxy)quinoline

CAS Number 124495-18-7

Pesticide 

Classification Fungicide 

Physical/

chemical 

property data

Molecular Weight 308.14 g/mol

Water Solubility at 

20o

C (ppm)

0.116, distilled water

0.128, pH 5 buffer

0.047, pH 7 buffer

0.036, pH 9 buffer

Low solubility at pH 

7

Vapor pressure 

(25o

C) 1.5 x 10-7 torr

Should exist in both 

vapor and particulate 

phases

 
6

Parameter Value Description Reference

Henry's Law 

Constant at pH 7

1.29 x10-6 atm· m 3·mole -1

(Calculated)

Not likely to 

volatilize from water 

or wet surfaces

Log Octanol/Water 

Partition coefficient 

(log Kow)

4.66

Hydrophobicpotential to 

bioaccumulate

45360712

Persistence

Hydrolysis 

At 50°C quinoxyfen was stable at pHs

7 and 9, over a 21 day study period. A 

half-life of 6.35 days was measured at 

pH 4.

Stable at neutral to 

alkaline pH

MRID 

45360620

Direct photolysis in 

water at pH 7

t1/2= <1 day (observed half-life). 

Quinoxyfen was detected only at day 

1, at 0.76% of the applied amount in 

buffer solution. 

CFBPQ (2-chloro-10-

fluoro[l]benzopyrano[2,3,4-

de]quinoline) was found as degradate 

with t1/2= 1.2 day.

Non-persistent

MRID 

45360623 

The aqueous photo-transformation of

dual 14C quinoxyfen was studied at 

25°C in sterile aqueous pH 5 (acetate) 

buffer solutions.

t1/2= 10.81 minutes

MRID 

45360624

Photolysis on soil

t1/2=74 days

degradate 5,7-dichloroquinoline-4-01 

(DCHQ) was present at small amounts 

(<10% AR)

Moderately persistent MRID 

45360625

Aerobic soil 

metabolism

t1/2 = 495 days (sandy clay loam), 433 

days (clay loam), 210 days (loamy 

sand), 577 days (sandy loam) Moderately persistent 

to persistent

MRIDs 

45360626, 

45360627

t1/2 = 102 days (sandy loam), 315 days 

(loam), 110 days (sandy loam), 257 

days (loam)

MRID 

45360628

Anaerobic soil 

metabolism t1/2= 289 days Persistent MRID 45360711

Anaerobic Aquatic 

metabolism t1/2= 18 days Slightly persistent MRID 45360629

Aerobic aquatic 

metabolism

t1/2 = 50 days in aerobic flooded sandy 

loam soil Moderately persistent MRID 45360630

Field Dissipation

Terrestrial field 

dissipation

t1/2= 94 days (sandy loam, CA)

Moderately persistent

MRID 

45360704

t1/2= 65 days (loam, Ontario Canada) MRID 

45360705
7

Parameter Value Description Reference

Half-life not determined (sandy clay 

loam, Ile de France)

Half-life not determined (loamy silt 

Germany)

Half-life not determined (sandy clay 

loam, Oxfordshire England)

The half-life was not 

determined due to 

inadequate sampling 

intervals; only 2-3 

samples were 

collected each year 

of the study.

MRIDs 453607-

08, -09,-10

Mobility

Leaching and 

absorption/desorption

Koc and Kd in mL/g

21,550 and 366, sandy clay loam

18,339 and 385, loamy sand

28,897 and 433, loamy sand

Hardly mobile

MRID 

45360701

53,401 and 252, loam

61,523 and 146, loam 

45,287 and 73, sand

75,178 and 1,803, loam

75,930 and 311, clay

MRID 

45360703

Fish Bioconcentration

Bioconcentration in 

fish (BCF)

5040X

High BCF

MRID 

45360425

9101 X (fish)

26,705X (green algae)*

18,865X (waterfleas)*

MRID 

48488501

AR=Applied Radioactivity

Classification of persistency was based on Goring scale, 1975. 

Mobility was described using FAO, 2000.

*BCF may reflect sorption to surfaces of test organisms.

Quinoxyfen has a high potential to bioconcentrate (BCF range: 5040-9101x) in fish tissue where 

it is not extensively metabolized. However, in one study quinoxyfen depurated rapidly when 

exposure to the compound was halted (half-life=2.7 d, MRID 45360425) and in another study 

depuration was relatively slow (observed half-life ~22 d, MRID 48488501). 

Finally, two non-guideline studies (MRID: 48488501) were submitted to measure the 

bioconcentration factor in the nonvascular aquatic green alga (Pseudokirchneriella subcapitata) 

and the freshwater invertebrate waterflea (Daphnia magna). The bioconcentration factors 

reported for these species at steady state were 26,705x (in algae) and 18,865x (in waterfleas), 

with depuration half-lives of 13.2 hours and 10.6 hours, respectively. 

The calculated BCF values in invertebrates and algae may also reflect sorption of the chemical to 

test surfaces of the organisms, as opposed to bioconcentration per se (SCHER, 2011). The high 

Koc and Kow of quinoxyfen suggest that the compound will partition to benthic sediments and/or 

move into the benthos through run-off of sediment-bound residues and may represent a potential 

source for quinoxyfen to enter aquatic food chains where it may bioconcentrate/bioaccumulate.
8

In two terrestrial field dissipation studies, dissipation half-lives (DT50) ranged from 65 to 94 days 

in loam and sandy loam, respectively. Additionally, three dissipation studies were conducted 

with sandy clay loam soils and loamy silt; however, half-lives could not be derived due to 

inadequate sampling intervals (only 2-3 sampling intervals were collected per year). Although 

these latter three did not provide definitive DT50 values, the studies lasted 5 years and 

quinoxyfen was detected throughout the study period, indicating that quinoxyfen is likely to 

persist in soil.

a. Transformation Products

The predominant degradates of quinoxyfen are: 2-oxo-quinoxyfen (USEPA 2010); 5, 7-

dichloroquinolin-4-ol (DCHQ), 2-chloro-10-fluoro[l]benzopyrano[2,3,4-delquinoline (CFBPQ), 

and 5,7-dichloro-4-methoxyquinoline (DCMQ). Table 3 summarizes the transformation products 

of quinoxyfen and their maximum amounts formed for the respective environmental fate studies 

in which they were detected.

The transformation product DCHQ was identified as a major degradate in the hydrolysis study 

(higher than 10% of the applied radioactivity, AR) and accounted for 85, 3.20 and 0.99% of 

applied radioactivity (AR) at pH 4, 7, and 9, respectively at 21 days. Similarly, this degradate 

was present at up to 17% AR in an aerobic soil metabolism study.

In photolysis in water (MRID 453606-24), CFBPQ accounted for 91.4% of the applied 

radioactivity at 1 hour and declined to 0.1% by 7 days. Numerous minor transformation products 

(<10% AR) were isolated but not all were identified.

Another major degradate is 2-oxo-quinoxyfen (formerly referred to as 3-OH quinoxyfen, USEPA 

2010) which was present in high amounts (>10% AR) in aerobic and anaerobic soil and aquatic 

metabolism studies.

Lastly, DCMQ was detected in aerobic soil metabolism study but only at lower amounts

(<10%AR).
9

Table 3. Quinoxyfen and Its Major Environmental Degradates

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)

PARENT

Quinoxyfen

CAS No.: 124495-18-7

Formula: C15H8Cl2NFO

MW: 308.14 g/mol

Smile string: 

c1c(Cl)cc2nccc(Oc3ccc(F)c

c3)c2c1Cl

TRANSFORMATION PRODUCTS

2-oxo-quinoxyfen*

5,7-dichloro-4-(4-

fluorophenoxy)-2-

(1H)-quinolone

Formula: C15H8Cl2NFO2

MW: 324.14 g/mol

Smile string:

C1(=CC(=CC2=C1C(=CC(

N2[H])=O)OC3=CC=C(C=

C3)F)Cl)Cl

Aerobic soil 

metabolism 45360628

sandy loam 

61 (365) 

62 (365)

sandy loam 

61 (365) 

59.4 (365)

loam 

18.9 (365) 

14.5 (365)

loam 

18.9 (365) 

14.5 (365)

Anaerobic soil 

metabolism 45360711 Sand 

9.13 (32)

Sand 

6.0 (100)

Anaerobic 

aquatic

metabolism

45360629 Sediment

83.2 (378) 

Sediment

83.2 (378)

Aerobic 

aquatic 

metabolism

45360630 40.6 (48) 33.5 (100)

Terrestrial 

field 

dissipation

45360704 0-15 cm 

4.9 (122)

0-15 cm

<4.9 (519)

45360705 0-15 cm 0-15 cm
10

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)

2.5 (372) <LOD (489)

DCHQ

5,7-

dichloroquinolin4-ol 

CAS No.: 171850-29-6

Formula: C9H5Cl2NO

MW:214.05 g/mol

Smile string: 

C1(=CC(=CC2=C1C(=CC=

N2)O[H])Cl)Cl

Hydrolysis 45360620

85 at pH 4

3.2 at pH 7

0.99 at pH 

9

85 at pH 4 (21)

3.2 at pH 7 (21)

0.99 at pH 9 (21)

Photolysis in 

soil 45360625 2.5 (30) 2.5 (30)

Aerobic soil 

metabolism

45360626 

45360627 3.13 (150) 1.54 (200)

Aerobic soil 

metabolism 45360628

sandy loam

0.4 (300)

9.7(240)

Loam

17.1 (365)

sandy loam 

0 (365)

7.7 (365)

Loam

17.1 (365)

Terrestrial 

field 

dissipation

45360704 6.9 (30) <LOD (519)

45360705 9.7 (62) Not reliable 

detection

CFBPQ

2-chloro-10-fluoro7a,11adihydrochromeno[2,

3,4-de]quinoline

Formula: C15H7ClNO

MW: 271.678 g/mol

Smile string: 

C12=C3C=C(C=C1N=CC=

C2OC4=C3C=C(C=C4)F)C

l

Photolysis in 

water 45360623 42.5 (1) Not detected (28)

Photolysis in 

water 45360624 91 (1 hr) 1.7 (7)
11

Code Name/ 

Synonym Chemical Name Chemical Structure Study Type Ref.

(MRID)

Maximum 

%AR (day)

Final %AR 

(study length)

DCMQ

5,7-dichloro-4-

methoxyquinoline

Formula: C10H7Cl2NO

MW:228.08

Smile string: 

C1(=CC(=CC2=C1C(=CC=

N2)OC)Cl)Cl

Aerobic soil 

metabolism 45360628

Sandy loam 

3.3 (300) 

Loam

3.3 (365)

Sandy loam 

0 (365)

Loam 

3.3 (365)

CO2

CAS No: 124-38-9

Formula: CO2

MW: 44.01 g/mol

Smile string: C(=O)=O

Aerobic soil 

metabolism

45360628

Sandy loam

14.5 (365)

4.3 (365)

loam

22.5(365)

5.7 (365)

Sandy loam

14.5 (365)

4.3 (365)

loam

22.5(365)

5.7 (365)

45360626 

& 

45360627

1.89 (150) 1.79 (200)

*Previously called 3-OH-quinoxyfen.
12

6. Receptors

The most sensitive aquatic and terrestrial toxicity data for quinoxyfen and its degradates 

are summarized in Table 4 and Table 5, respectively. Quinoxyfen is very highly toxic to 

aquatic invertebrates including D. magna (freshwater invertebrate), mysid shrimp (A. 

bahia; estuarine/marine crustacean), and Eastern oysters (Crassostrea virginica;

estuarine/marine mollusk) on an acute exposure basis. The compound is highly toxic to

the freshwater rainbow trout (Oncorhynchus mykiss) on an acute exposure basis. 

Definitive acute toxicity endpoints could not be established for the estuarine/marine

sheepshead minnow (Cyprinodon variegatus) and the freshwater bluegill sunfish 

(Lepomis macrochirus) due to the low solubility (0.047 mg/L at 25oC at pH 7) of 

quinoxyfen.

On a chronic exposure basis, freshwater fathead minnows (Pimephales promelas) 

exhibited reductions in growth (body length; NOAEC=13 μg ai/L). In the

estuarine/marine sheepshead minnow, larval survival and growth (standard length and 

blotted wet weight) were the most sensitive measured endpoints (NOAEC=4.09 μg 

a.i./L). The freshwater invertebrate D. magna exhibited reduced growth (length) and 

reduced number of offspring following chronic exposure (NOAEC=27 μg a.i./L). 

Sediment toxicity data are available for non-biting midge larvae, Chironomus riparius

(freshwater invertebrate), which show reduced emergence (NOAEC=128 μg a.i./L) 

following a 27-day exposure period; exposure was expressed in terms of water column 

concentrations rather than the preferred sediment pore water concentrations. In a 28-day 

life-cycle toxicity study with mysid shrimp, a definitive NOAEC could not be established 

since effects on reproduction (young per reproductive day) were observed at the lowest 

test level (0.91 μg a.i./L), in which a 19% reduction in mean number of offspring per 

female per reproductive day was observed relative to the negative control. However, it 

should be noted that the mean number of offspring per female per reproductive day in the 

mysid study was higher in the 0.91 μg a.i./L treatment level than in the solvent control, 

indicating a potential solvent effect.

Quinoxyfen exhibits low acute toxicity to terrestrial animals. It is practically non-toxic to 

birds (Northern bobwhite quail, Colinus virginianus, and mallard duck, Anas 

platyrhynchos) on both an acute oral and subacute dietary exposure basis and is 

practically nontoxic to rats (Rattus norvegicus) on an acute oral exposure basis. 

Quinoxyfen is also practically non-toxic to young adult honeybees on an acute contact 

exposure basis. 

Chronic exposure to northern bobwhite quail resulted in decreased numbers of live/viable 

embryos and hatchling survival/eggs set (NOAEC=483 mg a.i./kg-diet). Chronic 

exposure to mallards resulted in decreased survival of 14-day old chicks at both the 

lowest (229 mg a.i./kg-diet) and highest (933 mg a.i./kg-diet) concentrations tested. 

Therefore, the original DER for this study (MRID 45360412) concluded that the NOAEC 

was non-definitive (i.e., NOAEC <229 mg a.i./kg-diet) because significant reductions in 

14-day survivorship were detected at the lowest test level. However, based on current 

EFED policy, 14-day survival is only considered as a ratio with another study measure 
13

such as number of normal hatchlings or eggs set, and the 14-day survival endpoint is no 

longer considered appropriate for risk assessment. Therefore, the most sensitive endpoint 

from this study is currently based on decreased numbers of live/viable embryos and the 

ratio of hatchling survival/eggs set at the highest test level (NOAEC=465 mg a.i./kgdiet). 

A two-generation reproduction study with Sprague-Dawley rats (R. norvegicus) resulted 

in decreased body weights in offspring from chronic exposure (NOAEC=20 mg/kgbw/day).

In pre-emergent (seedling emergence) terrestrial plant toxicity testing, none of the 10 

plant species tested exhibited a phytotoxic response following exposure to quinoxyfen at 

concentrations equivalent to an application rate of 0.5 lbs a.i./A. In vegetative vigor 

testing, only one of the 10 species tested exhibited a statistically significant phytotoxic 

response. The dicotyledonous (dicot) cucumber (Cucumis sativus) was found to exhibit 

reduction in fresh weight when exposed to quinoxyfen, with a effect concentration for 

25% of the plants tested, i.e., EC25, value of 0.37 lbs a.i./A and a NOAEC of 0.06 lbs 

a.i./A. In both the seedling emergence and vegetative vigor studies, all species were 

exposed to a single concentration of 553 g/ha (0.5 lbs a.i./acre), except for cucumber 

which was tested at 0.06, 0.14, 0.26, and 0.5 lbs ai/A.

In a 7-day toxicity study of freshwater vascular plants with Lemna gibba (duckweed), no 

significant differences were observed in frond number, growth rate, or dry weight 

endpoints relative to controls at any of the concentrations tested (NOAEC and EC50 

values are 35 and >35 μg a.i./L, respectively).

Acute toxicity testing on nonvascular aquatic plants using green algae, Raphidocelis 

subcapitata (formerly Pseudokirchneriella subcapitata and Selenastrum capricornutum) 

the freshwater diatom, Navicula pelliculosa, and the saltwater diatom, Skeletonema 

costatum, resulted in EC50 values of 51, 30, and 130 μg a.i./L, respectively, and were 

within the solubility range of quinoxyfen.

Table 4. Summary of the Most Sensitive Toxicity Endpoints for Quinoxyfen.

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

Aquatic Organisms

Freshwater 

Fish§

Oncorhynchus mykiss

(Rainbow Trout)

LC50

(96 hours)

270 μg a.i./L

(Mortality)

45360413

(Supplemental)

Pimephales promelas

(Fathead Minnow)

NOAEC

(28 days)

13 μg a.i./L

(Growth: length)

45360424

(Acceptable)

Freshwater 

Invertebrates

Daphnia magna

(Water Flea)

EC50

(48 hours)

83 μg a.i./L*

(Immobility)

45360417

(Acceptable)

NOAEC

(21 days)

27.8 μg a.i./L

(Growth; reproduction)

45360423

(Supplemental)
14

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

Estuarine/

Marine Fish

Cyprinodon variegatus

(Sheepshead minnow)

LC50

(96 hours)

>168 μg a.i./L

(Mortality)

45360420

(Supplemental)

NOAEC

(39 days)

4.1 μg a.i./L

(Growth; Survival)

48102302

(Acceptable)

Estuarine/

Marine 

Invertebrates

Crassostrea virginica

(Eastern Oyster)

EC50

(96 hours)

72 μg a.i./L

(Shell Deposition)

45360421

(Acceptable)

Americamysis bahia

(Mysid shrimp)

NOAEC

(28 days)

<0.91 μg a.i./L

(Reproduction)

48102301

(Supplemental)

Vascular Plants Lemna gibba

(duckweed)

EC50

(14 Days)

>35 μg a.i./L

(Frond number) 48387901

NOAEC (Acceptable)

(14 Days)

35 μg a.i./L

(Frond number)

Nonvascular 

Plants

Navicula pelliculosa

(freshwater diatom)

EC50

(120 Hours)

30 μg a.i./L

(Cell Density)

45360615

(Acceptable)

Raphidocelis 

subcapitata 

(green algae)

NOAEC

(120 hours)

6.36 μg a.i./L

(Cell Density)

45360610

(Supplemental)

Terrestrial Organisms

Avian‡

Colinus virginianus

(Northern Bobwhite 

Quail)

LD50

(14 days)

>2,292 mg a.i./kg-bw

(Survival)

45360407

(Acceptable)

LC50

(8 days)

>5,620 mg/kg-diet

(Survival)

45360409

(Acceptable)

Anas platyrhynchos

(Mallard Duck)

NOAEC

(27 weeks)

465 mg a.i./kg-diet†

(numbers of live/viable 

embryos and hatchling 

survival/eggs set)

45360412

(Supplemental)

Mammals Rattus norvegicus

(Laboratory Rat)

LD50 >5,000 mg a.i./kg-bw 45360616

(Acceptable)

NOAEL 20 mg a.i./kg-bw

400 mg a.i./kg-diet

45360522

(Acceptable)

Terrestrial 

Invertebrates

Apis mellifera

(European Honeybee)

LD50

(48 hours) >100 μg/bee 45360617(Acceptable)

Plants

(Vegetative 

Vigor)

Dicots

EC25

0.366 lbs a.i./A

(plant weight)

45360607

(Acceptable)

NOAEC 0.064 lbs a.i./A

(plant weight)

Monocots

EC25

>0.5 lbs a.i./A

(no effects at highest 

concentration tested)

NOAEC

0.5 lbs a.i./A

(no effects at highest 

concentration tested)

Plants

(Seedling 

Emergence)

Dicots EC25

>0.5 lbs a.i./A

(no effects at highest 

concentration tested)
15

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

NOAEC

0.5 lbs a.i./A

(no effects at highest 

concentration tested)

Monocots

EC25

>0.5 lbs a.i./A

(no effects at highest 

concentration tested)

NOAEC

0.5 lbs a.i./A

(no effects at highest 

concentration tested)

* Previous risk assessments used the LC50 value from this study of 91 μg a.i./L, however, the EC50 based on 

immobility is more appropriate for risk assessment since immobile daphnids are considered to be dead.

† In a memo date May 8, 2006 (DP Barcode D328427), the NOAEC for this study was changed from <292 

to 465 mg a.i./kg-diet.

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

§ Freshwater are surrogates for aquatic-phase amphibians

Since the last risk assessment of quinoxyfen, a mallard reproduction study with the 

transformation product 2-oxo-quinoxyfen was reviewed (48991801). This study was 

requested because of the likely formation and persistence of 3-OH quinoxyfen coupled 

with its structural similarity to the parent2. At the highest test level in the submitted study 

(464 ppm dietary test concentration), there was a significant (p< 0.05) increase in the 

number of eggs laid (37%) and the number of eggs set (38%) compared to controls. 

Based on the statistically significant increase on the number of eggs laid in the highest 

dietary treatment group, the NOAEC and LOAEC for mallards exposed to the degradate 

are 243 and 464 mg a.i./kg diet, respectively. Since the lowest endpoint for the 2-oxoquinoxyfen avian reproduction study is lower than the lowest endpoint for the parent 

compound, the NOAEC from the 2-oxo-quinoxyfen study will be used to represent the 

toxicity of the parent compound for risk estimation during risk assessment.

Toxicological studies with D. magna indicate that both DCHQ and 2-oxo-quinoxyfen are 

at least five times less toxic than the parent compound. In addition, DCHQ is at least an 

order of magnitude less toxic to green algae as compared to quinoxyfen.

Table 5. Summary of Degradate Toxicity Data

Group Species Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

DCHQ

Freshwater 

Invertebrates Daphnia magna EC50(48 Hours) >500 μg a.i./L 45360419(Supplemental)

Nonvascular 

Plants

Raphidocelis 

subcapitata 

EC25

(96 Hours) >500 μg a.i./L 45360611

(Supplemental)

 2 An avian reproduction study was submitted for 2-oxo-quinoxyfen rather than 3-OH quinoxyfen because 

2-oxo quinoxyfen was initially misidentified as 3-OH quinoxyfen in metabolism studies.
16

Group Species Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

(green algae) NOAEC

(96 Hours) 500 μg a.i./L

2-oxo-Quinoxyfen

Freshwater 

Invertebrates Daphnia magna EC50(48 Hours) >500 μg a.i./L 45360418(Supplemental)

Avian Anas platyrhynchos NOAEC 243 mg a.i./kg-diet* 48991801

(Acceptable)

* 2-oxo-quinoxyfen avian reproduction toxicity endpoint will be used to represent the parent (quinoxyfen) 

in risk estimation since birds were more sensitive to the transformation product as compared to the parent 

on a chronic exposure basis.

a. Ecological Incidents

The Ecological Incident Information System (EIIS) is an OPP database that houses 

ecological incidents that have been reported to the Agency. When available, EIIS 

includes date and location of an incident, type and magnitude of effects observed in 

various species, use(s) of pesticides known or suspected of contributing to the incident, 

and results of any chemical residue analysis or other analyses conducted during incident 

investigation. EIIS incidents are categorized according to the certainty that the incident 

resulted from pesticide exposure. The Avian Monitoring System (AIMS) is a database 

administered by the American Bird Conservancy that contains publicly available data on 

reported avian incidents involving pesticides. Many of the incidents listed in this 

database are also in the EIIS. 

A search of the EIIS for ecological incidents run on April 25, 2013 identified only a 

single incident that may have resulted from exposure to quinoxyfen. Incidents included in 

EIIS are defined by a certainty index associated with the likelihood that the pesticide 

application described resulted in the observed incident. The certainty index defines 

incidents as unrelated, unlikely, possible, probable and highly probable. The only 

incident with quinoxyfen (I019772-008) involved damage to a cherry crop (i.e., plant 

damage) in California that was classified as “possible.” One note of uncertainty 

associated with this database is the nature of reporting of incidents. Many more incidents 

may have occurred due to quinoxyfen exposures but may not have been reported due to 

various factors, such as a lack of reporting, or a lack of observation of effects. Therefore, 

the lack of incident reports does not necessarily indicate the absence of incidents.

No plant or wildlife incidents have been reported through OPP’s aggregate incident 

report database and no avian incidents have been captured in the Avian Incident 

Monitoring System (AIMS; American Bird Conservancy 2009)3 as of April 25, 2013. 

 3 Available at: http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm
17

With respect to the one incident report on cherries, available toxicity data on quinoxyfen 

indicated that terrestrial plants are relatively insensitive to the compound; however, one 

dicot, i.e., cucumber, did provide a definitive EC25 of 0.366 lbs a.i./A.

7. Exposure Pathways of Concern

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

biologically significant concentrations. An exposure pathway is the means by which a 

pesticide moves in the environment from a source to an ecological receptor. For an 

ecological pathway to be complete, it must include a source, a release mechanism, an 

environmental transport medium, a point of exposure for ecological receptors, and a 

feasible route of exposure.

The environmental fate properties of quinoxyfen indicate the following transport 

mechanisms for potential exposure to aquatic and terrestrial organisms:

• Direct contact

• Spray drift

• Runoff

• Ingestion

The environmental fate properties and use patterns of quinoxyfen indicate that direct 

spray, spray drift, and runoff represent potential transport mechanisms of quinoxyfen to 

aquatic and terrestrial organisms. Drinking water and inhalation exposure pathways were 

screened using the SIP Screening Imbibition Program (SIP) and Screening Tool for 

Inhalation Risk (STIR) screening models and were found to be exposure pathways of low 

concern (no LOC exceedances are expected). SIP and STIR are described in detail at: 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm.

Both environmental fate properties (i.e., Kow and Koc) and BCF studies suggest that 

quinoxyfen has the propensity to bioaccumulate in the aquatic environment. Due to 

potential bioaccumulation concerns for quinoxyfen, KABAM (KOW-based Aquatic 

Bioaccumulation Model) version 1.0 will be used to estimate potential bioaccumulation 

of quinoxyfen residues in the aquatic food web and the subsequent risks these residues 

pose to terrestrial organisms consuming aquatic species. The bioaccumulation portion of 

KABAM is based upon work by Arnot and Gobas (2004) who parameterized a 

bioaccumulation model based on polychlorinated biphenyl (PCB) compounds and certain 

pesticides (e.g., lindane, DDT) in freshwater aquatic ecosystems. KABAM relies on a 

chemical's Kow to estimate uptake and elimination constants through respiration and diet 

of organisms in different trophic levels. Pesticide tissue residues are calculated for 

organisms at different trophic levels in aquatic food webs. The model then uses pesticide 

tissue concentrations in aquatic animals to estimate dose- and dietary-based exposures 

and associated risks to mammals and birds (surrogate for terrestrial-phase amphibians 
18

and reptiles) consuming aquatic organisms. Additional information about KABAM can 

be found in the program user guide.4

8. Analysis Plan

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

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

quinoxyfen are characterized and integrated to assess the risks. This is accomplished 

using a risk quotient (ratio of exposure concentration to effects concentration) approach. 

Although risk is often defined as the likelihood and magnitude of adverse ecological 

effects, the risk quotient-based approach does not provide a quantitative estimate of 

likelihood and/or magnitude of an adverse effect. However, as outlined in the Overview 

Document (USEPA, 2004), the likelihood of effects to individual organisms from 

particular uses of quinoxyfen is estimated using the probit dose-response slope and either 

the level of concern (discussed below) or actual calculated risk quotient value.

This analysis plan will be revisited and may be revised depending upon the information 

submitted by the public in response to the opening of the Registration Review docket for 

quinoxyfen.

a. Stressors of Concern

i. Ecological Risk Assessment

The stressors of concern are as follows:

• Terrestrial Environment: quinoxyfen (parent) and 2-oxo-quinoxyfen 

(transformation product)

• Aquatic Environment: quinoxyfen (parent)

The degradate 2-oxo-quinoxyfen (formerly identified as 3-OH quinoxyfen, USEPA 

2010)) was considered a major degradate in the drinking water assessment (USEPA 

2013b) due to the structural similarities with the parent compound. Dow AgroSciences 

(DAS) provided new information (MRIDs: 467613-01, 48133-01C and USEPA 2010) 

that demonstrated that 2-oxo-quinoxyfen is the correct degradate identified in the fate 

studies and not 3-OH-quinoxyfen that was previously identified. Therefore, 2-oxoquinoxyfen is considered a major degradate in the drinking water assessment due to 

structural similarities with the parent compound. Due to the more sensitive endpoint for 

avian reproduction from 2-oxo-quinoxyfen versus the parent, 2-oxo-quinoxyfen is also 

being considered and stressor of concern for terrestrial ecological risk assessment. 

Conversely, for aquatic ecological risk assessment, only the parent is considered to be of

concern due to the demonstrated low toxicity of transformation products as compared 

with the parent. 

 

 4 http://www.epa.gov/oppefed1/models/water/
19

ii. Drinking Water 

The drinking water assessments conducted to support the registration review human 

health risk assessments of quinoxyfen will incorporate model estimates of residues of 

concern, which are parent compound and the 2-oxo-quinoxyfen degradate (USEPA, 

2003; USEPA 2010), in surface and ground water source drinking water. The Health 

Effects Division does not have sufficient data on the 2-oxo-quinoxyfen degradate to 

discount its potential toxicity. Therefore, quinoxyfen and 2-oxo-quinoxyfen will be 

assessed together using a total toxic residues approach.

b. Measures of Exposure 

EFED will use standard available models to evaluate potential exposures to aquatic and 

terrestrial organisms as described at 

http://www.epa.gov/pesticides/science/models_db.htm.

i. Available Monitoring Data

The Agency is not aware of surface or ground water monitoring conducted by federal and 

state agencies. However, if new monitoring data of quinoxyfen becomes available, it will 

be considered in the assessment.

c. Measures of Effect 

Toxicity data presented in Section 3 of this problem formulation will be used to calculate 

risk quotients. Any additional information submitted by the registrant or found in the 

open literature prior to conduct of the risk assessment meeting the standards established 

by the Agency will also be considered. The open literature studies are identified using 

EPA’s ECOTOXicology database (ECOTOX)5

, which employs a literature search engine 

for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The 

evaluation of both sources of data can also provide insight into the direct and indirect 

effects of pesticides on biotic communities from loss of species that are sensitive to the 

chemicals and from changes in structure and functional characteristics of the affected 

communities.

9. Endangered Species Assessments

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

the Agency will evaluate risks to listed species from registered uses of pesticides in 

registration review. The process for evaluating potential risks to listed species is further 

described at http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm.

 5 http://cfpub.epa.gov/ecotox/
20

10. Endocrine Disruptor Screening Program

Quinoxyfen was not included in the first group of 67 chemicals issued an order to 

conduct Tier 1 EDSP testing. For additional information the EDSP program, visit 

http://www.epa.gov/endo/. 

11. Preliminary Identification of Data Gaps 

a. Environmental Fate

Environmental Chemistry Methods (ECM) for Soil and Water and Associated 

Independent Laboratory Validation (ILV), OCSPP Guideline 850.6100 is needed to 

support field dissipation studies.

ECM and ILV are not available for the methods used in the field dissipation studies, 

though this is a requirement for acceptance of such studies. Environmental chemistry 

methods in water as well as soil (along with associated ILV) are required in field 

dissipation and ground water monitoring studies under the OCSPP 835 Environmental 

Fate Test Guidelines, or used in field studies of terrestrial and aquatic organisms and 

plants under the OCSPP 850.

Table 6 identifies environmental fate studies, by MRID, that provide data for each 

guideline requirement, as well as study classifications and whether or not further data are 

needed in order to support risk assessment. No environmental fate data for degradates 

have been submitted; however at this time no studies on quinoxyfen degradates are 

needed for risk assessment.

Table 6. Submitted Environmental Fate Data for Quinoxyfen.

OCSPP

Guideline

Data 

Requirement

Submitted 

MRIDs

Study 

Classification

Are data needed 

to conduct risk 

assessment?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

835.2120 Hydrolysis 45360620 Acceptable No

835.2370 Aqueous 

Photolysis

45360623,

45360624

Supplemental 

Supplemental

No

835.2410 Soil Photolysis 45360625 Acceptable No 

835.4100 Aerobic Soil 

Metabolism 45360626 Supplemental No
21

OCSPP

Guideline

Data 

Requirement

Submitted 

MRIDs

Study 

Classification

Are data needed 

to conduct risk 

assessment?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

45360627 Acceptable

835.4200 Anaerobic Soil 

Metabolism 45360711 Supplemental No

835.4300 Aerobic Aquatic 

Metabolism 45360630 Acceptable No

835.4400 Anaerobic 

Aquatic 

Metabolism

45360629 Acceptable No

835.1230

Adsorption/Deso

rption batch 

equilibrium

45360701 Supplemental No

45360703 Acceptable

835.1240 Aged Column 

Leaching 45360702 Supplemental No

835.1410 Lab Volatility 45461303 Supplemental No 

835.6200 Terrestrial; Field 

Dissipation

45360704 Acceptable

No

45360705 Acceptable

45360708 Supplemental

45360709 Supplemental

45360710 Supplemental

835.6100 Aquatic Field 

Dissipation

45360706 Not reviewed -- 45360707 Not reviewed

850.6100 

Environmental 

Chemistry 

Methods (ECM) 

and Independent 

Laboratory 

Validation (ILV) 

in soil and water

N/A Not submitted Yes

This is a standard 

data requirement for 

field dissipation and 

ground water 

monitoring studies. 

ECM and associated 

ILV are not available 

for the method used 

in the field 

dissipation studies, 

though this is a 

requirement for 

acceptance of such 

studies. 
22

OCSPP

Guideline

Data 

Requirement

Submitted 

MRIDs

Study 

Classification

Are data needed 

to conduct risk 

assessment?

Justification and 

Assumptions EPA 

will Make in 

Absence of Data

850.1730 Bioconcentration 

in Fish

45360425

48488501

48488501

48488501

Acceptable 

Acceptable

Supplemental

Supplemental

No

b. Effects

Table 7 identifies ecological effects studies with quinoxyfen, by MRID, for each 

guideline requirement, as well as study classifications and whether or not additional data 

are needed in order to support risk assessment. Rationale for the additional data 

requested is presented below the tables. Table 8 identifies ecological effects studies with 

transformation products of quinoxyfen.

Table 7. Submitted Ecological Effects Data for Quinoxyfen

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

Avian and Mammalian Testing

850.2100

Avian acute oral 

toxicity, 

waterfowl

—TGAI

None N/A No

Avian acute oral 

toxicity, upland 

game bird 

species

—TGAI

45360407 Acceptable No

Five concentrations tested; no 

treatment-related mortalities. 

Study tests up to doses greater 

than 10 times the dose-based 

EEC across uses and dietary 

items.

Avian acute oral 

toxicity, 

passerine 

species—TGAI

None N/A No

Study is not recommended 

because of low acute oral toxicity 

to upland game birds and low 

dietary toxicity to upland game 

birds and waterfowl

850.2200

Avian dietary 

toxicity, 

waterfowl 

species—TGAI

45360410 Acceptable No

Five concentrations tested; no 

treatment-related mortalities. 

Study tests up to concentrations 

greater than 10 times the dietary 

EEC across uses and dietary 

items.
23

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

Avian dietary 

toxicity, upland 

game bird—

TGAI

45360409 Acceptable No

Five concentrations tested; no 

treatment-related mortalities. 

Study tests up to concentrations 

greater than 10 times dietary 

EEC across uses and dietary 

items.

850.2300

Avian 

reproduction, 

waterfowl 

species—TGAI

45360412 Supplemental No

Avian 

reproduction, 

upland game bird 

species—TGAI

45360411 Acceptable No

850.2400 Wild mammal 

toxicity—TGAI None N/A No

Not triggered based on 

ecotoxicity data, predicted EECs, 

fate properties, and use pattern 

criteria.

850.2500

Simulated or 

actual field 

testing—TEP

None N/A No

Not triggered based on 

ecotoxicity data, predicted EECs, 

fate properties, and use pattern 

criteria.

Aquatic Animal Testing

850.1010

Freshwater 

invertebrate, 

acute toxicity—

TGAI

45360417 Acceptable No

850.1025

Estuarine/Marine 

Mollusk acute 

toxicity—TGAI

45360421 Acceptable No

850.1035 Estuarine/Marine 

crustacean acute 

toxicity—TGAI

45360422 Acceptable No

850.1075

Freshwater fish, 

acute toxicity, 

warm water 

species—TGAI

45360414 Supplemental No

Freshwater fish, 

acute toxicity, 

cold water 

species—TGAI

45360413 Supplemental No
24

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

Freshwater fish, 

acute toxicity, 

additional 

species—TGAI

45360416 Supplemental No

Study performed with Cyprinus 

carpio, which is not a 

recommended species for acute 

toxicity testing; however, results 

may be useful for risk 

assessment.

Estuarine/Marine 

fish acute 

toxicity—TGAI

45360420 Supplemental No

850.1300

Freshwater 

invertebrate,

reproduction 

test—TGAI

45360423 Supplemental No

Replicate data were not provided 

for statistical verification of dry 

weight data.

850.1350

Estuarine/marine 

invertebrate,

reproduction 

test—TGAI

48102301 Supplemental Yes

Study did not establish a 

NOAEC. Effects on number of 

offspring per reproductive day 

were observed at all 

concentrations tested. 

850.1400

Freshwater fish, 

early life stage 

test—TGAI

45360424 Acceptable No

Saltwater fish, 

early life stage 

test—TGAI

48102302 Acceptable No

850.1500

Freshwater fish 

life cycle test None N/A No

Aquatic EECs are < 0.1 of the 

FW fish early life-stage (ELS) 

NOAEC (13 μg a.i./L).

Estuarine/marine 

fish life cycle 

test

None N/A No

Aquatic EECs are < 0.1 of the 

EM fish early life-stage (ELS) 

NOAEC (4.1 μg a.i./L).

850.1950

Simulated or 

actual field 

testing for 

aquatic 

organisms

None N/A No

Higher tier testing to address risk 

uncertainties have not been 

identified at this time.

NonGuideline

Freshwater fish 

21-day subchronic toxicity 

test

45360415 Supplemental No

Subchronic testing with 

freshwater fish is not required, 

but study results may be useful 

for risk assessment.
25

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

Sediment Testing

850.1735

Whole sediment 

10-d freshwater 

invertebrate—

TGAI

None N/A Yes

Data requirement triggered since 

KOC and log Kow values in 

submitted fate studies were 

above 1,000 and 3.0, respectively 

(see Appendix E and data 

justification below table for 

further details) 

850.1740

Whole sediment 

10-d 

estuarine/marine 

invertebrate—

TGAI

None N/A Yes

Data requirement triggered since 

KOC and log Kow values in 

submitted fate studies were 

above 1,000 and 3.0, respectively 

(see Appendix E and data 

justification below table for 

further details)

Agencywide 

guideline

Whole sediment 

chronic 

freshwater and/or 

marine 

invertebrate—

TGAI

None N/A Yes

Data are recommended pending 

the outcome of the 10-day 

sediment toxicity studies 

(850.1735; 850.1740) (see 

Appendix E and data 

justification below table for 

further details)

Insect Pollinator Testing

850.3020

Honeybee acute 

contact 

toxicity—TGAI

45360616 Acceptable No

45360617 Acceptable No

Nonguideline

Honeybee acute 

oral toxicity 

study—TGAI 

453606178 Supplemental No

850.3030

Honeybee 

toxicity of 

residues on 

foliage—TEP

None N/A No Data requirement not triggered

850.3040 Field testing for 

pollinators None N/A No

Field testing to address risk 

uncertainties have not been 

identified at this time
26

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

NonguidelineLarval Toxicity 

Test—TGAI None N/A Yes

Data are only available on the 

toxicity of quinoxyfen to young 

adult bees; no information is 

available on toxicity of 

quinoxyfen to honeybee larvae. 

A honeybee larval toxicity test is 

part of EFEDs current screening 

process for terrestrial 

invertebrates.

A protocol should be submitted 

before conducting this test.

See Appendix E for further 

justification for recommending 

this study.

Terrestrial Plant Testing

850.4100

Seedling 

emergence (10 

species)—TEP 45360607 Acceptable

No Although not noted in the DER, 

quinoxyfen was tested as a 

suspension concentrate which the 

850.4150 study authors described as TEP

Vegetative vigor 

(10 species)—

TEP

No

Aquatic Plant Testing

850.4400

Aquatic plant 

growth, vascular 

plant 

—TGAI

48387901 Acceptable No

Test was conducted up to 

maximum experimental 

solubility limit

45360612 Supplemental No

NOAEC and EC05 could not be 

determined due to significant 

toxicity at all treatment levels.

850.4500*

Aquatic Plant, 

freshwater green 

alga species—

TGAI 

45360610 Supplemental No Extensive cell count variability in 

control groups

Aquatic Plant, 

freshwater 

diatom

—TGAI 

45360615 Acceptable No

Aquatic Plant, 

marine diatom

—TGAI

45360613 Supplemental No
27

Guideline Description—

Test Substance MRID Study Classification

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

850.4550†

Aquatic Plant, 

cyanobacterium

—TGAI 

45360614 Acceptable No

TGAI = Technical Grade Active Ingredient

TEP = technical end product

* Algal toxicity tests are now under guideline OCSPP 850.4500 (formerly 850.5400)

† Cyanobacterium tests are now under guideline 850.4550 (formerly 850.5400)

Table 8. Submitted Ecological Effects Data for Quinoxyfen Transformation 

Products.

Guideline Description—

Test Substance MRID

Study 

Classificatio

n

Are data 

Needed for 

Risk 

Assessment

?

Comments

(Justification and Assumptions 

EPA will Make in Absence of 

Data)

850.2300

Avian 

reproduction, 

waterfowl 

species—2-

OxoQuinoxyfen

48991801 Acceptable No Study review date: June 17, 2013

850.1010

Freshwater 

invertebrate, 

acute toxicity—

3-OH 

Quinoxyfen

45360418 Supplementa

l No Limit test; only nominal concentration was reported

invertebrate, 

acute toxicity—

DCHQ

45360419 Supplementa

l No Limit test; only nominal concentration was reported

850.4500*

Aquatic Plant, 

freshwater 

green alga 

species—

DCHQ 

45360611 Supplementa

l No

Only one limit concentration 

tested and test concentration was 

not measured during study.

* Algal toxicity tests are now under guideline OCSPP 850.4500 (formerly 850.5400)

12. References 

Goring, C.A. I.; Laskowki; D.A., Hamaker, J.H.; and Meikle, R.W. 1975. Principles of pesticide 

degradation in soil. pp. 135-172 in (Haque, R. and Freed, V.H. eds.) Environmental 

dynamics of pesticides. Plenum Press, NY.
28

USDA Crop Profiles. Available online at: http://www.ipmcenters.org/cropprofiles/CP_form.cfm

Food and Agriculture Organization of the United Nations. FAO Pesticide Disposal Series 8. 

Assessing Soil Contamination: A Reference Manual. Appendix 2. Parameters of 

pesticides that influence processes in the soil. Editorial Group, FAO Information 

Division: Rome, 2000. http://www.fao.org/docrep/003/X2570E/X2570E00.htm. 

Jones, R.D. et al., 2000. Guidance for use of the Index Reservoir and Percent Crop Area Factor 

in Drinking Water Assessments (March 21, 2000). Office of Pesticide Programs, 

Environmental Fate and Effects Division, U.S. Environmental Protection Agency. 

Arlington, VA.

SCHER (2011) SCHER (Scientific Committee on Health and Environmental Risks), Opinion on 

draft environmental quality standards under the Water Framework Directive –

quinoxyfen, 15 June 2011.

Wheeler, I. E., Hollomon, D. W., Gustafson, G., Mitchell, J. C., Longhurst, C., Zhang, Z. and 

Gurr, S. J. (2003). Quinoxyfen perturbs signal transduction in barley powdery mildew 

(Blumeria graminis f.sp. hordei). Molecular Plant Pathology, 4: 177–186. doi: 

10.1046/j.1364-3703.2003.00165.x

USEPA. 1999. Guidance for Use of the Index Reservoir in Drinking Water Exposure 

Assessments. Arlington, VA.

USEPA. 2000. Drinking Water Screening Level Assessment. Part A: Applying a Percent Crop 

Area Adjustment to Tier II Surface Water Model Estimates for Pesticide Drinking Water 

Exposure Assessments. FQPA Science Policy Document .Public Comment Draft 

September 1, 2000. Federal Register: October 11, 2000 (volume 65, number 197). 

Electronic copy available at http://www.epa.gov/pesticides/trac/science/ .

USEPA. 2002a. Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides, Version II (February 28, 2002). Office of Pesticide 

Programs, Environmental Fate and Effects Division, U.S. Environmental Protection 

Agency. Arlington, VA.

USEPA. 2002b. Pesticide Root Zone Model (PRZM) Field and Orchard Crop Scenarios: 

Standard Procedures for Conducting Quality Control and Quality Assurance. Office of 

Pesticide Programs, Environmental Fate and Effects Division, U.S. Environmental 

Protection Agency. Arlington, VA.

USEPA 2003a. Quinoxyfen-Health Effects Division (HED) Metabolism Assessment Review 

Committee (MARC) Decision Document. Meeting date March 5, 2003. United States 

Environmental Protection Agency (USEPA). Health and Effects Division. 

USEPA 2003b. Environmental Fate and Ecological Risk Assessment for the

Registration of Quinoxyfen. United States Environmental Protection Agency (USEPA). 

Environmental Fate and Effects Division. Memorandum issue: August 5, 2003.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. United States Environmental Protection Agency (USEPA). Environmental 
29

Fate and Effects Division. Office of Pesticide Programs. Available at 

http://www.epa.gov/espp/consultation/ecorisk-overview.pdf.

USEPA 2008. Quinoxyfen: Tier I Drinking Water Exposure Assessment in Support of the

Proposed New Uses of Quinoxyfen on stone fruits group 12 (excluding cherry), 

artichokes, winter squash, pumpkin and edible gourds. United States Environmental 

Protection Agency (USEPA). Environmental Fate and Effects Division. Memorandum 

issued: October 20, 2008.

USEPA 2010. Response to Data Submission from Dow AgroSciences Dated June 24, 2010: 

Structure of Soil Metabolite. A MEMORANDUM from the Environmental Fate and 

Effects Division to Registration Division. DP Barcode 380219. Dated August 12, 2010.

USEPA 2013a. Reduced Risk Analysis: Quinoxyfen Use on Fruiting Vegetables Group 8-10B 

(Tomatoes). United States Environmental Protection Agency (USEPA). Environmental 

Fate and Effects Division. Memorandum issued: April 4, 2013.

USEPA 2013b. Tier I Drinking Water Assessment for the IR-4 New Use Petitions for the Use of 

Quinoxyfen on Fruiting Vegetables Group 8-10B, Small Fruit Vine Climbing Except 

Fuzzy Kiwifruit Subgroup 13-07F and Low Growing Berry Subgroup 13-07G. United 

States Environmental Protection Agency (USEPA). Environmental Fate and Effects 

Division. Memorandum issued: April 23, 2013.

USEPA, 2013c. Environmental Fate and Ecological Risk Assessment for Proposed Use of 

Quinoxyfen on Fruiting Vegetables Group 8-10B, Small Fruit Vine Climbing (Except 

Fuzzy Kiwifruit) Subgroup 13-07F and Low Growing Berry Subgroup 13-07G. United 

States Environmental Protection Agency (USEPA). Environmental Fate and Effects 

Division. Memorandum issued: May 22, 2013.

USEPA. 2013d. BEAD Chemical Profile for Registration Review: Quinoxyfen (121027). 

Memorandum From Don Atwood, Jihad Alsadek and Stephen Smearman to Bonnie 

Alder. Biological and Economic Analysis Division to Pesticide Reevaluation Division.
30

Appendix A. Submitted Environmental Fate and Effects Studies

SUBMITTED FATE STUDIES (as of 06/04/13)

161-1 Hydrolysis

MRID Citation Reference

45360619 Cowlyn, T. (1993) XDE-795 (Pure): Determination of Hydrolysis as a Function 

of pH; Amended Final Report: Lab Project Number: GHE-P-3072. 

Unpublished study prepared by Pharmaco-LSR Ltd. 32 p. 

45360620 Reeves, G.; Ghosh, D. (1994) The Hydrolysis of (carbon 14)-XDE-795: Lab 

Project Number: GHE-P-3137. Unpublished study prepared by DowElanco 

Europe. 90 p. 

45461302 Baloch, R. (1997) Effects of Buffer and Co-Solvent on the Hydrolysis of DE795: Lab Project Number: GHE-P-6328: E97-041. Unpublished study prepared 

by DowElanco Europe. 45 p. 

161-2 Photodegradation-water

45360621 Rudel, H. (1995) Determination of the Quantum Yield of XDE-795 in Water: 

Lab Project Number: GHE-P-4429. Unpublished study prepared by 

Umweltchemie und Okotoxikologie--IUCT. 62 p. 

45360622 Portwood, D. (1996) Identification of DE-795 in Photolysis Products: Lab 

Project Number: GHE-P-4721. Unpublished study prepared by DowElanco 

Europe. 68 p. 

45360623 MacDonald, A. (1997) The Photolysis of (carbon 14)-DE-795 Under Natural 

Conditions: Lab Project Number: GHE-P-5932: 26Q. Unpublished study 

prepared by DowElanco Europe. 101 p. 

45360624 Yoder, R.; Schwedler, D. (2001) Aqueous Photolysis of Quinoxyfen in pH 

Buffer Under Xenon Light: Lab Project Number: 000116. Unpublished study 

prepared by Dow AgroSciences LLC. 104 p. 

161-3 Photodegradation-soil

45360625 Reeves, G. (1995) The Soil Photolysis of (carbon 14)-XDE-795: Lab Project 

Number: GHE-P-4111: 16Q. Unpublished study prepared by DowElanco 

Europe. 74 p. 

162-1 Aerobic soil metabolism

45360626 Reeves, G. (1993) The Aerobic Soil Degradation/Metabolism of (carbon 14)-

XDE-795 and the Effect of Environmental Conditions on its Degradation Rate: 

Lab Project Number: GHE-P-2990. Unpublished study prepared by DowElanco 

Europe. 78 p. 

45360627 Ghosh, D.; Portwood, D. (1994) Identification of Soil Metabolism Products of 

XDE-795 by Particle-Beam Liquid Chromatography Mass Spectrometry and 
31

Thermospray Liquid Chromatography Mass Spectrometry: Lab Project 

Number: GHE-P-3079. Unpublished study prepared by DowElanco Europe. 52 

p. 

45360628 Krieger, M.; Smith, K.; Balcer, J. (2001) Aerobic Soil Metabolism of 

Quinoxyfen: Lab Project Number: 990062. Unpublished study prepared by 

Dow AgroSciences LLC. 145 p. 

162-2 Anaerobic soil metabolism

45360711 Phillips, M.; Hall, B. (1995) The Degradation of Radiolabelled XDE-795 in 

Soul Under Anaerobic Conditions: Lab Project Number: GHE-P-4374. 

Unpublished study prepared by Inveresk Research International. 57 p. {OPPTS 

835.3400} 

162-3 Anaerobic aquatic metab.

45360629 Krieger, M.; Smith, K.; Balcer, J. (2001) Anaerobic Aquatic Metabolism of 

Quinoxyfen: Lab Project Number: 990063. Unpublished study prepared by 

Dow AgroSciences LLC. 88 p. 

162-4 Aerobic aquatic metab.

45360630 Batzer, F.; Simon, K. (2001) The Aerobic Aquatic Metabolism of Quinoxyfen: 

Lab Project Number: 000135. Unpublished study prepared by Dow 

AgroSciences LLC. 98 p. 

163-1 Leach/adsorp/desorption

45360701 Reeves, G. (1994) The Adsorption/Desorption of (carbon-14)-XDE-795 in Soil: 

Lab Project Number: GHE-P-3592. Unpublished study prepared by DowElanco 

Europe. 53 p. 

45360702 Reeves, G. (1994) The Leaching Characteristics of Aged (carbon-14)-XDE-795 

Soil Residues: Lab Project Number: GHE-P-3552. Unpublished study prepared 

by DowElanco Europe. 52 p. 

45360703 Sarff, P.; Damon, A. (2001) Soil/Sediment Adsorption Desorption of 

Quinoxyfen, 3-Hydroxyquinoxyfen, and 5,7-Dichloro-4-hydroxyquinoline for 

US Registration: Lab Project Number: 11344088-5029-1: 000372: 46296. 

Unpublished study prepared by ABC Laboratories, Inc. 224 p. 

163-2 Volatility - lab

45461303 Ruedel, H. (1997) Testing of the Volatilisation Potential of XDE-795: 

Volatilisation from Plant Surfaces, Volatilisation from Soil: Lab Project 

Number: DOW-025/7-22 (15Q). Unpublished study prepared by FraunhoferInstitut fuer Umweltchemie und Oekotoxikologie. 62 p. 

164-1 Terrestrial field dissipation
32

45360704 Roberts, D.; Foster, D. (2001) Field Dissipation of Quinoxyfen Under 

California Irrigated Conditions: Lab Project Number: 990025: A020.004. 

Unpublished study prepared by Dow AgroSciences LLC and Excel Research 

Services, Inc. 162 p. 

45360705 Roberts, D.; Foster, D. (2001) Field Dissipation of Quinoxyfen in Ontario, 

Canada: Lab Project Number: 990046. Unpublished study prepared by Dow 

AgroSciences LLC and Vaughn Agricultural Research Services, Ltd. 170 p. 

164-2 Aquatic field dissipation

MRID Citation Reference

45360706 Olberding, E. (2001) Method Validation Report for the Determination of 

XDE-795 (Quinoxyfen) and the 3-Hydroxy Metabolite Residues in Soil Using 

Dow AgroSciences Method ERC 94.27: Lab Project Number: GH-C 5193: 

ERC 94.27. Unpublished study prepared by Dow AgroSciences Europe. 39 p. 

{OPPTS 850.7100} 

45360707 Olberding, E.; Foster, D. (2001) Method Validation Report for the 

Determination of Quinoxyfen and Metabolites in Soil by Gas Chromatography 

with Tandem Mass Spectrometry Detection Using Dow AgroSciences Method 

GRM 00.16: Lab Project Number: 000420: GRM 00.16. Unpublished study 

prepared by Dow AgroSciences LLC. 50 p. {OPPTS 850.7100} 

165-1 Confined rotational crop

45360713

Haq, R.; Brown, G. (1995) Uptake of XDE-795 into Three Succeeding Crops: 

Lab Project Number: GHE-P-4322: 9 Q. Unpublished study prepared by 

DowElanco Europe. 56 p. {OPPTS 860.1850} 

Non-Guideline Study Selections

45360708 Gambie, A. et al. (1999) Residues of Quinoxyfen and its 3-Hydroxy 

Metabolite in Soil Following Five Annual Applications of EF-1186, Northern 

France - 1993: Lab Project Number: GHE-P-7336R: R93-041. Unpublished 

study prepared by Dow AgroSciences. 56 p. 

45360709 Gambie, A. et al. (1999) Residues of Quinoxyfen and its 3-Hydroxy 

Metabolite in Soil Following Five Annual Applications of EF-1186, Germany: 

Lab Project Number: GHE-P-7337R: RF93-42: RL93-42. Unpublished study 

prepared by Dow AgroSciences. 78 p. 

45360710

Khoshab, A. (2000) Residues of Quinoxyfen and its 3-Hydroxy Metabolite in 

Soil Following Five Annual Applications of EF-1186, UK-Final Report: Lab 

Project Number: GHR-P-8686: R93-43. Unpublished study prepared by Dow 

AgroSciences Europe. 65 p. 

45360712 Krieger, M.; Roberts, D. (2001) Environmental Fate Summary of Quinoxyfen: 

Lab Project Number: GH-C 5200. Unpublished study prepared by Dow 
33

AgroSciences LLC. 81 p. 

45360719 Rawle, N.; Gambie, A. (1995) Independent Validation of DowElanco Method 

ERC 94.27 for the Determination of Residues of XDE-795 and its 3-Hydroxy 

Metabolite in Soil: Lab Project Number: REV95-03: GHE-P-4184: ERC 

94.27. Unpublished study prepared by CEM Analytical Services Ltd. 49 p. 

45360725 Gambie, A. (2001) The Stability of XDE-795 and the 3-Hydroxy Metabolite 

in Soil Under Frozen Storage Conditions (30 Months): Lab Project Number: 

GHE-P-7935: ST94-11. Unpublished study prepared by Dow AgroSciences 

Europe. 29 p. 

48133301 Terando, N. (1995) Synthesis of 5,7-Dichloro-4-(4-Fluorophenoxy)-3-

Hydroxyquinoline (X510421, DE-795 Metabolite). Project Number: 

GH/C/3841. Unpublished study prepared by DowElanco. 52 p.

48133302 Terando, N. (1999) Synthesis of 5,7-Dichloro-4-(4-Fluorophenoxy)-3-

Hydroxyquinoline (Quinoxyfen, DE-795 Metabolite). Project Number: 

GH/C/4915. Unpublished study prepared by Dow AgroSciences, LLC. 25 p.

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

45360407 Campbell, S.; Lynn, S. (1992) XDE-795 Fungicide An Acute Oral Toxicity Study with 

the Northern Bobwhite: Lab Project Number: ES-DR-0325-7474-5: ES-2543. 

Unpublished study prepared by Wildlife International Ltd. 21 p. 

45360408 Lehr, K.; Rathkamp, W. (1992) 5,7-Dichloro-4-(4-Fluorophenoxy) Quinoline (XR795): Stability in Prepared Game Bird Starter Ration: Lab Project Number: ES-DR0325-7474-3. Unpublished study prepared by Wildlife International Ltd. 16 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

45360409 Campbell, S.; Lynn, S. (1992) XDE-795 Fungicide A Dietary LC50 Study with the 

Northern Bobwhite: Lab Project Number: 103-377: ES-2541: ES-DR-0325-7474-7. 

Unpublished study prepared by Wildlife International Ltd. 20 p. 

45360410 Campbell, S. (1992) XDE-795 Fungicide A Dietary LC50 Study with the Mallard: Lab 

Project Number: 103-378: ES-2544: ES-DR-0325-7474-6. Unpublished study prepared 

by Wildlife International Ltd. 21 p. 

71-4 Avian Reproduction

MRID Citation Reference

45360411 Helsten, B. (1999) Avian Reproductive Toxicity Study with Quinoxyfen in Bobwhite 

Quail: Lab Project Number: 153-017-07: 981046. Unpublished study prepared by BioLife Associates, Ltd. 443 p. 
34

45360412 Pedersen, C. (2000) Avian Reproductive Toxicity Study with Quinoxyfen in Mallard 

Ducks: Lab Project Number: 153-019-08: 990104. Unpublished study prepared by BioLife Associates, Ltd. 389 p. 

47682501 Temple, D. (2007) 2-Oxo-Quinoxyfen Metabolite: A Reproduction Study with the 

Mallard. Project Number: 379/031607/MR/100P/4. Unpublished study prepared by 

Wildlife International, Ltd. 16 p.

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

45360413 Woodburn, K.; Hugo, J.; Kirk, H. (1993) The Acute 96-Hour Toxicity of XDE-795 to 

the Rainbow Trout, Oncorhynchus mykiss Walbaum: Lab Project Number: DECO-ES2635. Unpublished study prepared by The Dow Chemical Company. 29 p. 

45360414 Rick, D.; Hugo, J.; Kirk, H. et al. (1993) XDE-795 Fungicide: Acute 96-Hour Flowthrough Toxicity in Bluegill, Lepomis macrochirus Rafinesque: Lab Project Number: 

DECO-ES-2659. Unpublished study prepared by The Dow Chemical Company. 31 p. 

45360415 Rick, D.; Weinberg, J.; Martin, M. et al. (1994) Evaluation of the Prolonged (21-

Day)Toxicity of XDE-795 Fungicide to the Rainbow Trout, Oncorhynchus mykiss 

Walbaum: Lab Project Number: DECO-ES-2668. Unpublished study prepared by The 

Dow Chemical Company. 35 p. 

45360416 Sword, M.; Bowman, J.; Muckerman, M. (1996) Acute Static Renewal Toxicity of 

XDE-795 Fungicide to Common Carp (Cyprinus carpio): Lab Project Number: 42597: 

GHE-T-621. Unpublished study prepared by ABC Laboratories, Inc. 289 p. 

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

45360417 Milazzo, D.; Brown, R.; Servinski, M et al. (1993) XDE-795 Fungicide: Acute Toxicity 

to the Daphnid, Daphnia magna Straus: Lab Project Number: DECO-ES-2600. 

Unpublished study prepared by The Dow Chemical Company. 26 p. 

45360418 Marino, T.; Staley, J. (2000) 5,7-Dichloro-4-(4-Fluorophenoxy)-3-Hydroxyquinoline 

(3-Hydroxy-DE-795): An Acute Toxicity Study with the Daphnid, Daphnia magna 

Straus: Lab Project Number: 001134. Unpublished study prepared by The Dow 

Chemical Company. 23 p. 

45360419 Marino, T.; Staley, J. (2000) 5,7-Dichloro-4-(4-Fluorophenoxy)-3-Hydroxyquinoline 

(3-Hydroxy-DE-795): An Acute Toxicity Study with the Daphnid, Daphnia magna 

Straus: Lab Project Number: 001132. Unpublished study prepared by The Dow 

Chemical Company. 23 p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

45360420 Boeri, R.; Wyskiel, D.; Ward, T. (2000) Quinoxyfen (XDE-795) Technical: Acute 

Toxicity Study to the Sheepshead Minnow, Cyprinodon variegatus: Lab Project 

Number: 000108: 2040-DO. Unpublished study prepared by T.R. Wilbury 

Laboratories, Inc. 25 p. 
35

45360421 Boeri, R.; Wyskiel, D.; Ward, T. (2000) Quinoxyfen (XDE-795) Technical: Oyster 

Shell Deposition Test: Lab Project Number: 2034-DO: 000106. Unpublished study 

prepared by T.R. Wilbury Laboratories, Inc. 24 p. 

45360422 Boeri, R.; Wyskiel, D.; Ward, T. (2000) Quinoxyfen (XDE-795) Technical: Acute 

Toxicity to the Mysid, Americamysis bahia: Lab Project Number: 2033-DO: 000107. 

Unpublished study prepared by T.R. Wilbury Laboratories, Inc. 26 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

45360424 Rhodes, J.; Downing, J.; Muckerman, M. (1996) Early Life-Stage Toxicity of XDE-795 

Technical to the Fathead Minnow (Pimephales promelas) Under Flow-through 

Conditions: Lab Project Number: 42536: GHE-T-590. Unpublished study prepared by 

ABC Laboratories. 634 p. 

48102301 Aufderheide, J. (2006) Quinoxyfen: Life Cycle Toxicity Test of the Saltwater Mysid, 

Americamysis bahia, Conducted Under Flow-Through Test Conditions. Project 

Number: 49242, 040427. Unpublished study prepared by ABC Laboratories, Inc. 68 p.

72-5 Life cycle fish

MRID Citation Reference

45360423 Kirk, H.; Servinski, M.; Milazzo, D. et al. (1995) XDE-795 Fungicide: Evaluation of 

the Chronic Toxicity (21-Day Flow-Through) to Daphnia magna Straus: Lab 

Project Number: DECO-ES-2603. Unpublished study prepared by The Dow 

Chemical Company. 77 p. 

123-1 Seed germination/seedling emergence and vegetative vigor

MRID Citation Reference

A.

45360607 McCormick, R. (2001) Effect of Quinoxyfen on the Emergence and Vegetative Vigor 

of Non-Target Terrestrial Plants (Tier I/II): Lab Project Number: 000127. Unpublished 

study prepared by ABC Labs., Inc. 40 p. 

45360610 Milazzo, D. (1993) XDE-795: The Toxicity to the Green Alga Selenastrum 

capricornutum Printz: Lab Project Number: DECO-ES-2606. Unpublished study 

prepared by The Dow Chemical Co. 32 p. 

123-2 Aquatic plant growth

MRID Citation Reference

45360609 Mallett, M. (1999) The Toxicity of 3-Hydroxy-Quinoxyfen to the Freshwater 

Unicellular Green Alga Selenastrum capricornutum: Lab Project Number: GHE-T-902. 

Unpublished study prepared by CEM Analytical Services Ltd. 65 p. 

45360611 Kirk, H.; Gilles, M. (2000) 5,7-Dichloro-4-(1H)-Quinoline (DCHQ): Growth Inhibition 

Test with the Freshwater Green Alga, Selenastrum capricornutum Printz: Lab Project 

Number: 001140. Unpublished study prepared by The Dow Chemical Co. 23 p. 

45360612 Kirk, H.; Gilles, M.; McClymont, E. et al. (2000) Effects of Quinoxyfen (DE-795) on 

the Growth of the Aquatic Plant, Duckweed, Lemna gibba L. G-3: Lab Project Number: 
36

991225. Unpublished study prepared by The Dow Chemical Co. 37 p. 

45360613 Kirk, H.; Gilles, M.; McClymont, E. et al. (2000) Effects of Quinoxyfen (DE-795) on 

the Growth of the Saltwater Diatom, Skeletonema costatum: Lab Project Number: 

991226. Unpublished study prepared by The Dow Chemical Co. 37 p. 

45360614 Kirk, H.; Gilles, M.; McClymont, E. et al. (2000) Effects of Quinoxyfen (DE-795) on 

the Growth of the Freshwater Bluegreen Alga, Anabaena flos-aquae: Lab Project 

Number: 991227. Unpublished study prepared by The Dow Chemical Co. 36 p. 

45360615 Kirk, H.; Gilles, M.; McClymont, E. et al. (2000) Effects of Quinoxyfen (DE-795) on 

the Growth of the Freshwater Diatom, Navicula pelliculosa: Lab Project Number: 

991228. Unpublished study prepared by The Dow Chemical Co. 40 p.

141-1 Honey bee acute contact

MRID Citation Reference

45360616 Hoxter, K.; Bernard, W.; Smith, G. (1992) XDE-795 Fungicide: An Acute Contact 

Toxicity Study with the Honey Bee: Lab Project Number: 103-380C: ES-2542. 

Unpublished study prepared by Wildlife International Ltd. 21 p. 

45360617 Palmer, S.; Beavers, J. (1993) XDE-795 Fungicide: An Acute Contact Toxicity Study 

with the Honey Bee: Lab Project Number: 103-401D: ES-2562. Unpublished study 

prepared by Wildlife International Ltd. 21 p. 

45360618 Palmer, S.; Beavers, J. (1993) XDE-795 Fungicide: A Dietary Toxicity Study with the 

Honey Bee: Lab Project Number: ES-2676: 103-400. Unpublished study prepared by 

Wildlife International Ltd. 19 p. 

850.1400 Fish early-life stage toxicity test

MRID Citation Reference

48102302 Hicks, S. (2005) Quinoxyfen: Early Life-Stage Toxicity Test with the Sheepshead 

Minnow, Cyprinodon variegatus, under Flow-Through Conditions. Project Number: 

49241, 040426. Unpublished study prepared by ABC Laboratories, Inc. 77 p.

850.2100 Avian acute oral toxicity test

MRID Citation Reference

47783301 Hubbard, P. (2009) MTF-753: An Acute Oral Toxicity Study with the Zebra Finch 

(Poephila guttata). Project Number: 236/011209/ZF/LD/SUB236. Unpublished study 

prepared by Wildlife International, Ltd. 11 p.

850.2300 Avian reproduction test

MRID Citation Reference

47682501 Temple, D. (2007) 2-Oxo-Quinoxyfen Metabolite: A Reproduction Study with the 

Mallard. Project Number: 379/031607/MR/100P/4. Unpublished study prepared by 

Wildlife International, Ltd. 16 p.

850.4400 Aquatic plant toxicity test using Lemna spp. Tiers I and II
37

MRID Citation Reference

48387901 Softcheck, K. (2010) Quinoxyfen - 7-Day Toxicity Test with Duckweed (Lemna 

gibba). Project Number: 11344019, 12550/6574. Unpublished study prepared by 

Smithers Viscient Laboratories. 70 p.

 Non-Guideline Study

MRID Citation Reference

45360426 Ward, T.; Kowaleski, P.; Boeri, R. (1993) Acute Toxicity of XDE-795 Fungicide to the 

Earthworm, Eisenia foetida: Lab Project Number: 85-DO: ES-2584. Unpublished study 

prepared by T.R. Wilbury Laboratories, Inc. 23 p. 

45360427 England, D.; Leak, T. (1996) Chronic Toxicity of (carbon 14)-XDE-795 Technical to 

Chironomus riparius from Aqueous Application in a 27-day Exposure with Sediment: 

Lab Project Number: 42535: GHE-T-641R. Unpublished study prepared by ABC 

Laboratories, Inc. 70 p. {OPPTS 850.1790} 

45360600 Dow AgroSciences LLC. (2001) Submission of Toxicity, Environmental Fate and 

Efficacy Data in Support of the Application for Registration of Quinoxyfen Technical, 

Quinoxyfen Manufacturing Use Concentrate and Quintec. Transmittal of 30 Studies. 
38

Appendix B. Complete Summary of Toxicity Endpoints for Quinoxyfen and 

Degradates.

Table B1. Toxicity Profile for Quinoxyfen.

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

Aquatic Organisms

Freshwater 

Fish¶

Oncorhynchus 

mykiss

(Rainbow Trout)

LC50

(96 hours)

270 μg a.i./L

(Mortality)

45360413

(Supplemental)

LC50

(21 days)

73.4 μg a.i./L

(Mortality) 45360415

NOAEC (Supplemental)

(21 days)

22 μg a.i./L

(Mortality and 

weight)

Lepomis 

macrochirus

(Bluegill Sunfish)

LC50

(96 hours)

>280 μg a.i./L

(Mortality)

45360414

(Supplemental)

Cyprinus carpio

(Common Carp)

LC50

(96 hours)

410 μg a.i./L

(Mortality)

45360416

(Supplemental)

Pimephales 

promelas

(Fathead Minnow)

NOAEC

(28 days)

13

(Growth: length)

45360424

(Acceptable)

Freshwater 

Invertebrates

Daphnia magna

(Water Flea)

EC50

(48 hours)

83 μg a.i./L‡

(Immobility)

45360417

(Acceptable)

NOAEC

(21 days)

27.8 μg a.i./L

(Growth; 

reproduction)

45360423

(Supplemental)

Chironomus riparius

(Non-Biting Midge)

EC50

(27 days) >508 μg a.i./L 45360427

NOAEC (Supplemental)

(27 days)

128 μg a.i./L

(emergence)

Estuarine/

Marine Fish

Cyprinodon 

variegatus

(Sheepshead 

minnow)

LC50

(96 hours)

>168 μg a.i./L

(Mortality)

45360420

(Supplemental)

NOAEC

(39 days)

4.1 μg a.i./L

(Growth; Survival)

48102302

(Acceptable)

Estuarine/

Marine 

Invertebrates

Crassostrea 

virginica

(Eastern Oyster)

EC50

(96 hours)

72 μg a.i./L

(Shell Deposition)

45360421

(Acceptable)

Americamysis bahia

(Mysid shrimp)

LC50

(96 hours)

74.3 μg a.i./L

(Survival)

45360422

(Acceptable)

NOAEC

(28 days)

<0.91 μg a.i./L

(Reproduction)

48102301

(Supplemental)
39

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

Vascular 

Plants

Lemna gibba

(duckweed)

EC50

(14 Days)

>35 μg a.i./L

(Frond number) 48387901

NOAEC (Acceptable)

(14 Days)

35 μg a.i./L

(Frond number)

Nonvascular 

Plants

Raphidocelis 

subcapitata 

(green algae)

EC50

(120 Hours)

51 μg a.i./L

(Cell Density) 45360610

NOAEC (Supplemental)

(120 hours)

6.36 μg a.i./L

(Cell Density)

Navicula pelliculosa

(freshwater diatom)

EC50

(120 Hours)

30 μg a.i./L

(Cell Density) 45360615

NOAEC (Acceptable)

(120 hours)

17.7 μg a.i./L

(Cell Density)

Skeletonema 

costatum

(marine diatom)

EC50

(120 Hours)

130 μg a.i./L

(Cell Density) 45360613

NOAEC (Supplemental)

(120 hours)

<54.6* μg a.i./L

(Cell Density)

Anabaena flos-aquae

(cyanobacterium)

EC50

(120 Hours) >1,240 μg a.i./L 45360614

NOAEC (Acceptable)

(120 hours) 1,240 μg a.i./L

Terrestrial Organisms

Avian§

Colinus virginianus

(Northern Bobwhite 

Quail)

LD50

(14 days)

>2,292 mg a.i./kg-bw

(Survival)

45360407

(Acceptable)

LC50

(8 days)

>5,620 mg/kg-diet

(Survival)

45360409

(Acceptable)

NOAEC

483 mg/kg-diet

(live 3-week 

embryos/viable 

embryos

45360411

(Acceptable)

Anas platyrhynchos

(Mallard Duck)

LC50

(8 days)

>5,620 mg/kg-diet

(Survival)

45360410

(Acceptable)

NOAEC

(27 weeks)

465 mg a.i./kg-diet†

(numbers of 

live/viable embryos 

and hatchling 

survival/eggs set)

45360412

(Supplemental)

Mammals Rattus norvegicus

(Laboratory Rat)

LD50 >5,000 mg a.i./kg-bw 45360616

(Acceptable)

NOAEL 20 mg a.i./kg-bw

400 mg a.i./kg-diet

45360522

(Acceptable)

Terrestrial 

Invertebrates

Apis mellifera

(European 

Honeybee)

LD50

(46 hours) >25 μg/bee 45360616(Acceptable)

LD50

(48 hours) >100 μg/bee 45360617(Acceptable)
40

Group Species

(Common Name)

Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

LD50

(48 hours) >1,000 μg/bee 45360618(Supplemental)

Eisenia fetida

(Earthworm)

LC50

(14 days) >923 mg/kg 45360426(Supplemental)

Plants

Dicots

EC25

0.366 lbs a.i./A

(plant weight)

45360607

(Acceptable)

NOAEC 0.064 lbs a.i./A

(plant weight)

Monocots

EC25

>0.5 lbs a.i./A

(no effects at highest 

concentration tested)

NOAEC

0.5 lbs a.i./A

(no effects at highest 

concentration tested)

* EC05 = 5.6 μg a.i./L

† In a memo date May 8, 2006 (DP Barcode D328427), the NOAEC for this study was changed 

from <292 to 465 mg a.i./kg-diet.

‡

Previous risk assessments used the LC50 value from this study of 91 μg a.i./L, however, the EC50

based on immobility is more appropriate for risk assessment since immobile daphnids are 

considered to be dead.

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

¶ Freshwater are surrogates for aquatic-phase amphibians

Table B2. Summary of Degradate Toxicity Data 

Group Species Endpoint

(Duration)

Toxicity Value

(Measured Effect)

MRID

(Study 

Classification)

DCHQ

Freshwater 

Invertebrates Daphnia magna EC50(48 Hours) >500 μg a.i./L 45360419(Supplemental)

Nonvascular 

Plants

Raphidocelis 

subcapitata 

(green algae)

EC25

(96 Hours) >500 μg a.i./L 45360611

NOAEC (Supplemental)

(96 Hours) 500 μg a.i./L

3-OH Quinoxyfen

Freshwater 

Invertebrates Daphnia magna EC50(48 Hours) >500 μg a.i./L 45360418(Supplemental)

2-oxo Quinoxyfen

Avian Anas platyrhynchos NOAEC 243 mg a.i./kg-diet 489918-01

(Acceptable)
41

Appendix C. Results from the Screening Tool for Inhalation Risk Assessment 

(STIR)
42

Appendix D. Results from Screening Imbibition Program (SIP)
43

Appendix E. Data Call-In Justification Tables

Study Title: Honeybee Larval Toxicity Study

Guideline Number: Non-guideline

Test Substance: Quinoxyfen—TGAI

Rationale for Requiring the Data

Although quinoxyfen is practically non-toxic to adult worker bees on an acute contact exposure 

basis, a larval toxicity study is needed to determine the toxicity of the compound to developing 

brood. This study is part of EFED’s current screening level process for determining potential 

effects to terrestrial invertebrates. Therefore, a non-guideline honeybee larval toxicity study is 

recommended. The registrant should submit a proposed protocol for review and approval by 

EFED prior to initiation of the study.

Practical Utility of the Data

How will the data be used?

Data will be used to assess risk to non-target listed and non-listed terrestrial invertebrate species. 

This study would allow the Agency to refine the screening-level hazard assessment for beneficial 

terrestrial invertebrates. The effects data will be used to determine the potential for adverse effects 

on beneficial terrestrial invertebrates through direct effects on larval bees. 

How could the data impact the Agency’s future decision-making?

EPA is required by section 7(a)(2) of the Endangered Species Act (ESA) to ensure that any action 

it authorizes or takes “...is not likely to jeopardize the continued existence of any endangered or 

threatened species or result in the destruction or adverse modification of critical habitat” and “to 

use the best scientific data available” in carrying out this obligation. The data EPA intends to call 

in are necessary to inform the determination required by ESA as to whether continued registration 

of a pesticide is or is not likely to jeopardize the species or its designated critical habitat. The lack 

of these data will limit the flexibility that the Agency has in coming into compliance with ESA 

and could result in use restrictions that are unnecessarily severe. In addition, the lack of these data 

may result in an uncertain assumed risk and potential mitigation of quinoxyfen formulations under 

FIFRA.

Study Title: Whole sediment chronic freshwater and/or marine invertebrate (3 Studies)

Guideline Number: Agency-wide Guideline

Test Substance: Quinoxyfen—TGAI

Rationale for Requiring the Data

The use pattern, chemical properties, estimated exposure, and toxicity profile of quinoxyfen

indicate need for chronic (life cycle) sediment toxicity tests to fully evaluate potential risks to 

benthic invertebrates. These sediment toxicity studies include two freshwater species (the midge, 

Chironomus dilutus and the amphipod, Hyalella azteca) and one saltwater species (the amphipod, 

Leptocheirus plumulosus). Multiple species are being recommended in order to account for 

differential sensitivity and exposure potential of benthic invertebrates to quinoxyfen. This 

recommendation is being made because some KOC and log Kow values in submitted fate studies 

were above the thresholds of 1,000 and 3.0, respectively. The registrant should submit a proposed 

protocol for review and approval by EFED prior to initiation of the study.

(Note: As an alternative to the conduct of three chronic (life cycle) sediment toxicity tests, EFED 
44

would also consider a tiered testing approach for sediment toxicity testing. In this approach, 

sediment toxicity testing would first be conducted with the aforementioned species using the 10-d 

(subchronic) sediment toxicity test guidelines (OSCPP 850.17356 and 850.17407). Then, pending 

a comparison of estimated environmental concentrations (EEC) in sediment and pore water with 

toxicity results from the 10-d sediment toxicity studies, the need for one or more chronic sediment 

toxicity studies would be determined. This tiered testing approach has the potential advantage of 

reducing the number of chronic (life cycle) studies that would be needed when results of the 10-d 

(subchronic) tests in conjunction with sediment EECs indicate chronic testing is not likely to alter 

risk assessment conclusions. In some cases, however, this tiered testing approach may result in 

the conduct of both a 10-d (subchronic) and a chronic (life cycle) study. If the tiered test approach 

described above is not preferred, then chronic life-cycle sediment toxicity studies be carried out on 

the three preferred species, C. dilutus, H. azteca, and L. plumulosus.)

Practical Utility of the Data

How will the data be used?

Data from sediment toxicity studies will be used to estimate potential risks to benthic organisms 

associated with uses of quinoxyfen. The data will reduce uncertainties associated with the current 

risk assessment for benthic species and will improve our understanding of the potential effects of 

quinoxyfen on aquatic ecosystems.

How could the data impact the Agency’s future decision-making?

If the data indicates that registered quinoxyfen uses may pose a risk of adverse effects to nontarget benthic organisms above the Agency Level of Concern, the Agency may explore decision 

options to mitigate this risk. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act, and could result in 

use restrictions for quinoxyfen which may otherwise be avoided, or which are unnecessarily 

severe.

 6 USEPA. 1996. 

http://www.epa.gov/opptsmnt/pubs/frs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Gu

idelines/Drafts/850-1735.pdf 7 USEPA. 1996. 

http://www.epa.gov/opptsmnt/pubs/frs/publications/OPPTS_Harmonized/850_Ecological_Effects_Test_Gu

idelines/Drafts/850-1740.pdf