UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

PC Code: 028869

DP Barcode: D392988

MEMORANDUM

DATE:

SUBJECT:

TO:

THROUGH:

FROM:

May 8, 2012

Ecological Risk Assessment for Fluoxastrobin for the Proposed New Use on

Rice

Heather Garvie, Risk Manager Reviewer

Fungicide Branch

Registration Division (7504P)

Dana Spatz, Branch Chie~~J13)."" Rosanna Louie-Juzwiak, Risk Assessment Proce eade

Environmental Risk Branch III

Environmental Fate and Effects Division (7507P)

~.;;:-

Melissa Panger, Ph.D., Senior Scientist

Rochelle F. H. Bohaty Ph.D., Chemist~~ Environmental Risk Branch III

Environmental Fate and Effects Division (7507P)

The Environmental Fate and Effects Division (EFED) has completed a review ofthe new use

request for fluoxastrobin for use on rice. Ecological risk assessments have been conducted for

fluoxastrobin and various uses with application rates similar to or higher than those being proposed

for the new use on rice [see USEPA, 2004 (D2891 04); USEPA, 2008 (D349270, D349282);

USEPA, 2009 (D356983, D357729, D366187); USEPA, 2011 (D379112+)]. Therefore, an

abbreviated ecological risk assessment is provided here.

The risk assessment for the proposed new use offluoxastrobin on rice results in level of concern

(LaC) exceedences for listed and non-listed freshwater fish (RQs: acute = 0.21; chronic = 1.7),

freshwater invertebrates (RQs: acute 0.78; chronic = 2.1), and estuarine/marine invertebrates (RQs:

acute = 1.8; chronic = 152) on an acute and chronic exposure basis. The RQ for non-vascular

aquatic plants (RQ = 1.2) also exceeds the listed species LaC. Risks to terrestrial organisms

(animals and plants), estuarine/marine fish, and vascular aquatic plants are not expected from the
2

proposed new use for fluoxastrobin.

Data deficiencies and data gaps described in this assessment are similar to those identified in 

previous assessments (see D349270, D349282, D356983, D357729, D366187, D379112+) and are 

summarized below. The only exception is that new terrestrial plant studies have been submitted that 

had not been included in previous ecological risk assessments, but are considered here. In addition, 

this assessment also considers a recently submitted aquatic field dissipation study conducted on 

rice. This study has several deficiencies, but does provide characterization for the risk assessment.

The two new Tier I terrestrial plant studies show that the EC25 values for seedling emergence and 

vegetative vigor are greater than the concentration tested (i.e., >2.18 lb a.i./acre). The vegetative 

vigor study (MRID 48520002) is classified as acceptable. The seedling emergence study (MRID 

48520001) is classified as acceptable except for the results for lettuce, onion, and ryegrass which 

were invalidated due to poor emergence in the study controls (10%, 66%, and 52% emergence, 

respectively). Although, a seedling emergence study for lettuce, onion, and ryegrass remains a data 

gap for fluoxastrobin, additional plant data are not needed to evaluate the current action (i.e., the 

proposed new use on rice). Previous Tier I plant studies showed no effects at concentrations (i.e., 

0.54 lb a.i./acre) higher than the application rate proposed for the rice use (i.e., 0.18 lb a.i./acre). 

Whole sediment toxicity studies were originally requested as confirmatory data when fluoxastrobin 

was first registered (e.g., see the EPA‟s fluoxastrobin fact sheet from 20051). Two sediment toxicity 

studies were submitted to the EPA, but they were both classified as invalid (MRIDs 45865505 and 

45865506). Additionally, a microcosm study that included benthic organisms (MRID 46404901)

was submitted, but the study was classified as supplemental and does not fulfill guideline 

requirements for a sediment toxicity study. A qualitative description of the microcosm study acute 

endpoints and study deficiencies were provided in an EFED Memorandum (USEPA, 2005, 

D312642) and corresponding Data Evaluation Record. Therefore, EFED has recommended 

requesting sediment toxicity data in each ecological risk assessment conducted for new uses of 

fluoxastrobin since the chemical was first registered for use in the United States. In addition, the 

following studies listed below under the Data Gaps section were requested in a letter from the EPA 

to Arysta LifeScience North America Corporation regarding the master label amendments on 

December 18, 2008. The following studies remain data deficiencies and gaps for fluoxastrobin:

Data deficiencies:

A 96-hour acute study on the toxicity of technical fluoxastrobin to sheepshead minnow (MRID 

458654-17) does not meet guideline solubility limit recommendations for an acute toxicity study

(OCSPP 850.1075). The study may be upgraded to acceptable if documentation on the limit of 

fluoxastrobin solubility in saltwater under test conditions is provided to the EPA for review. The 

registrant previously requested that this study be upgraded to acceptable; however, the request was 

denied (see EFED Memorandum D334233, 2008).

Data gaps:

Whole Sediment: Acute Freshwater Invertebrates (OCSPP 850.1735): A 10-day spiked sediment 

 

1

http://www.epa.gov/opprd001/factsheets/fluoxastrobin.pdf 
3

study can address uncertainties regarding freshwater sediment-dwelling organisms. 

Whole Sediment: Acute Marine Invertebrates (OCSPP 850.1740): A 10-day spiked sediment study 

can address uncertainties regarding estuarine/marine sediment-dwelling organisms. 

Whole Sediment: Chronic Invertebrates Freshwater and Marine (OCSPP 850.1770; OCSPP

850.1760 or OECD 218): A 28-day spiked sediment study can address uncertainties regarding 

freshwater and estuarine/marine sediment-dwelling organisms. 
4

PROBLEM FORMULATION

Fluoxastrobin [(E)-{2-[6-(2-chlorophenoxy)-5-fluoropyrimidin-4-yloxy]phenyl}(5,6-dihydro-1,4,2-

dioxazin-3-yl)methanone O-methyloxime; CAS 361377-29-9; PC code 028869] was first registered 

in the United States in 2005 and is currently registered for use on a number of crops (see Use 

Characterization below). This assessment is for the proposed new use on rice.

Mode of Action

Fluoxastrobin is a “leaf-systemic” strobilurin fungicide. Strobilurin fungicides are site-specific 

compounds that provide significant control of plant diseases caused by pathogens. They work by 

interfering with respiration in plant-pathogenic fungi. These types of fungicides also possess 

translaminar activity, therefore enabling them to move through treated leaves and providing control 

on both leaf surfaces. Fluoxastrobin inhibits spore germination and mycelial growth. The chemical 

identification as well as physical-chemical properties of fluoxastrobin are provided in Table 1.

Table 1. Physical-Chemical Characteristics of Fluoxastrobin 

Chemical Name (E)-{2-[6-(2-chlorophenoxy)-5-fluoropyrimidin-4-yloxy]phenyl}(5,6-dihydro1,4,2-dioxazin-3-yl)methanone O-methyloxime

Chemical Structure

O

N N

O N

O

O

N

Cl F

O

CH3

Chemical Abstracts Service 

(CAS) Registry Number 361377-29-9

Molecular Formula C21H16ClFN4O5

USEPA Pesticide Code (PC #) 028869

Smiles Notation Clc4ccccc4Oc3ncnc(Oc2ccccc2C(=N\OC)/C=1OCCON=1)c3F

Molecular Weight 458.8 g/mol

Vapor Pressure (25 °C) 4.23 x 10-12 torr

Water Solubility

(20 °C)

2.3 mg/L

Henry‟s Law Constant 1.01 x 10-7Pa m3/ mole (9.98 atm - m

3

/mol)

Log Kow 2.86

Use Characterization

Fluoxastrobin is currently registered for use on peanut, tuberous and corm vegetables, leaf petioles,

fruiting vegetables, cucurbits, ornamentals, turf and as a seed treatment on potato, peanut and grass.

Maximum single application rates range from 0.12 to 0.55 lb a.i./a and maximum yearly application 
5

rates range from 0.24 to 2.2 lb a.i./a.2 Application methods currently registered include aerial, 

chemigation, and ground sprays. While the geographic extent of fluoxastrobin use is unknown, it is 

likely widespread based on the wide variety of approved uses. 

Arysta LifeScience North America, LLC has submitted a new use request for fluoxastrobin

[Fluoxastrobin 480 SC Fungicide, EPA Reg. No. 66330-64 (40.3% fluoxastrobin); this master label 

will be the basis of the following products: EVITO® SC Fungicide, DISARMTM 480 SC Fungicide 

(ABN: Armor TechTM DISARMTM 480 SC Fungicide), and Fluoxastrobin 480 SC Fungicide Seed 

Treatment] for use on rice. Fluoxastrobin 480 SC Fungicide is a suspension concentrate 

formulation containing a single active ingredient (40.3% fluoxastrobin). Table 2 presents the 

proposed application rates for the new proposed use and label amendments.

Table 2. Proposed Fluoxastrobin Application Rates For Use on Rice

Crop

Single Application 

Rate Range

lb a.i./acre

No. of 

Applications

Minimum 

Retreatment 

Interval

(days)

Max Annual 

Application 

Rate

lb a.i./acre/yr

Application 

Technique

Rice 0.18 2 27 0.36

Air, Ground, 

and 

Chemigation

The proposed use on rice is for a foliar application that can be applied with aerial, chemigation, and 

ground application equipment. The maximum number of proposed fluoxastrobin applications on 

rice is two per season with a maximum single application rate of 0.18 lb a.i./a and a minimum 

application interval of 27 days3(as shown in Table 2). The maximum yearly application rate is 

0.36 lb a.i./a. The label limits applications to 28 days prior to harvest. The label does not limit 

direct applications to flooded fields nor does it require a water holding period prior to discharging 

paddy water after fluoxastrobin applications. The geographic extent of the use is not specifically 

limited by the label; however, the majority of the rice production in the United States occurs in 

Arkansas, California, Mississippi, Missouri, Louisiana, and Texas. Survey data from the National 

Agricultural Statistics Service (NASS) on rice acres planted in the United States for the year 2010 

is provided in Table 3.

4 Rice has also been grown in Florida, Oklahoma, and Tennessee.5

 

2

For turf, the label permits four applications at a rate of 0.50 lb ai/A; however, the maximum yearly application rate is 

2.2 lb a.i./a; therefore, the maximum single application rate is assumed to be 0.55 lb a.i./a. The discrepancy is the result 

of the number of significant figures assumed in application rate conversion calculations. 

3 Email from Heather Garvie (EPA/RD) to Rosanna Louie-Juzwiak (EPA/EFED), March 15, 2012.

4

Survey data from the from the Quick Stats Database of the National Agricultural Statistics Service available at 

http://quickstats.nass.usda.gov/results/6432EC45-FA6F-3DE6-A48F-98F1917AAEA8

5

2007 census data from the Quick Stats Database of the National Agricultural Statistics Service available at 

http://quickstats.nass.usda.gov.
6

Table 3. Summary of Acres Planted With Rice in 20104

State Acreage Planted 

(x 1000) Percent Production(cwt) Percent

Arkansas 1,791 49% 115,675,000 48%

California 558 15% 44,326,000 18%

Louisiana 540 15% 32,625,000 13%

Mississippi 305 8% 20,756,000 9%

Missouri 253 7% 16,254,000 7%

Texas 189 5% 13,468,000 6%

United States 3,636 243,014,000

The following environmental hazards statement is included on the proposed label: 

“This pesticide is toxic to fish and aquatic invertebrates. Drift and runoff may be hazardous to 

aquatic organisms in water adjacent to treated areas. The active ingredient in this product can be 

persistent for several months or longer. Do not apply directly to water or to areas where surface 

water is present or to intertidal areas below the mean high water mark, or other sensitive areas 

that may be exposed to spray drift. Do not contaminate water when disposing of equipment 

washwater or rinsate.” 

Environmental Fate Summary

Based on laboratory studies, fluoxastrobin persists in soils for several months to more than a year,

and is slightly to moderately mobile in soils. As for aquatic environments, fluoxastrobin has been 

shown to be stable to hydrolysis. Fluoxastrobin is slightly susceptible to microbial degradation in 

aquatic environments. Aqueous photolysis of fluoxastrobin has been shown to be a major route of 

fluoxastrobin transformation in sterile water. However, an additional photolysis study performed in 

natural water/sediment systems indicates that the majority of applied fluoxastrobin sorbs to 

sediment and no transformation occurs under pseudo environmental conditions. Thus, the 

dissipation of fluoxastrobin in water is expected to depend on physical characteristics of the water 

(e.g., sediment loading, depth, etc.) which have an effect on sunlight penetration as well as the rate 

of fluoxastrobin sediment partitioning. Partitioning of fluoxastrobin between water and sediment 

was variable between submitted studies. Based on the log Kow fluoxastrobin is not expected to bio 

concentrate. This is supported by the fish bioaccumulation study. Environmental fate properties of 

fluoxastrobin are summarized in Table 4.

Table 4. Environmental Fate and Transport Characteristics of Fluoxastrobin

Parameter Data Study ID Study Status

Hydrolysis Half-life 

(t1/2)

pH 4: Stable

pH 7: Stable

pH 9: Stable

45865304 Acceptable

Aquatic Photolysis 

Half-life (t1/2)

pH 7: 4.1, 20.1, and 28.3 days 45865306 & 

45865403 Acceptable

Soil Photolysis

Half-life (t1/2)

Stable 45865308 Acceptable
7

Parameter Data Study ID Study Status

Aerobic Soil 

Metabolism

Half-life (t1/2)

29.4, 26.2, 30.1, 46.6, 323 and 393 

days1

45865309 & 

45865310 Acceptable

Aerobic Aquatic 

Metabolism Half-life 

(t1/2)

29 and 51 days (water)

363 and 271 (sediment)

190 and 150 days (total system)

45865313

469258062 Acceptable

Anaerobic Soil 

Metabolism half-life 

(t1/2)

No data

Anaerobic Aquatic 

Metabolism half-life 

(t1/2)

147 days (water)

211 days (sediment)

187 (total system)

45865312

469258062 Acceptable

Adsorption Coefficient 

(Kd)

26.26, 12.70, 16.21, and 3.35 mL/g

45865315 Supplemental

Soil Partition 

Coefficient (Koc)

1580, 629, 758, and 424 mL/g

Terrestrial Field 

Dissipation

578, 533, 347, and 239 days

45865318, 

45865320, 

45865323, & 

45865324

Acceptable

Aquatic Field 

Dissipation

Application 1: 6 days (water)3and 20 

days3(total system)

Application 2: 10 days (water)3and 135 

days4(total system)

48532004 Upgradable5

Fish BCF 18 45865421 Supplemental

1. There is a direct correlation with the level of soil microbial activity and the rate of degradation observed 

in the aerobic soil metabolism studies for fluoxastrobin. 

2. On February 1, 2006, the registrant responded (MRID 46925806) to the deficiencies in the data

evaluation report and the acceptability of the aerobic and anaerobic aquatic studies submitted in support 

of the fluoxastrobin registration (MRIDs 45865313 and 45865312, respectively). These studies were 

reevaluated and determined to be acceptable as EFED does not expect fluoxastrobin to sorb to the glass 

test apparatus to a sufficient degree to affect the study results, as demonstrated by the material balance.

3. Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media (final draft 

document December 21, 2011); Nth-Order Rate Model or Indeterminate Order Rate Equation Model 

(IORE) Representative half-life (TR IORE)

4. Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media (final draft 

document December 21, 2011); Double First-Order in Parallel (DFOP) second (“slow”) half-life (t1/2)

5. Data can only be used qualitatively for risk assessment purposes and should not be used as a rationale

for additional refinements. 

The two major soil metabolites of fluoxastrobin identified are HEC5725-E-des-chlorophenyl (HEC 

7155) and HEC5725-carboxylic acid (HEC 7180). The chemical identification as well as chemical 

structures of these transformation products are shown in Table 5. The only major degradate found 

in aqueous studies is HEC5725-oxazepine, which forms through direct photolysis in sterile water. 

An additional photolysis study performed in natural water/sediment systems indicates that the 

majority of applied fluoxastrobin adsorbs to sediment and no oxazepine forms under pseudo 

environmental conditions. This indicates aquatic photolysis of fluoxastrobin in the environment 

may be minimal as sediment partitioning reduces the available fluoxastrobin that may undergo 

photolysis. An aquatic field dissipation study (discussed in more detail below) does not report 
8

transformation products, a study deficiency; therefore, the formation of fluoxastrobin 

transformation products in the environment cannot be corroborated. Transformation is likely to be 

minimal based on the half-life of fluoxastrobin in the total system (water and sediment).

Table 5. Physical-Chemical Characteristics of Fluoxastrobin Transformation Products HEC

7155 and HEC 7180 

HEC7155

Chemical Name (5,6-dihydro-[1,4,2]dioxazin-3-yl)-[2-(5-fluoro-6-hydroxy-pyrimidin-4-yloxy)-

phenyl]-methanone O methyl-oxime

Chemical Structure

O

N N

O N

O

CH3

Cl F

O

OH

Molecular Formula C16H15FN4O5

Smiles Notation O(C1=C(C(=NC=N1)OC2=C(C=CC=C2)\C(=N/OC)C3=NOCCO3)F)C

Molecular Weight 362.32 g/mol

HEC 7180

Chemical Name {2-[6-(2-chlorophenoxy)-5-fluoropyrimidin-4-yloxy]-phenyl}-methoxyimino acetic 

acid

Chemical Structure

O

N N

O N

O

O

N

Cl F

O

CH3

Molecular Formula C19H13ClFN3O5

Smiles Notation ClC1=C(C=CC=C1)OC2=C(C(=NC=N2)OC3=C(C=CC=C3)\C(=N/OC)C(=O)O[H])F

Molecular Weight 417.78 g/mol

Terrestrial field dissipation studies indicate that fluoxastrobin persists for over a year. However, it 

was not observed to leach through soil. Out of the three major metabolites mentioned above, only 

HEC5725-E-des-chlorophenyl was detected in the terrestrial field studies. The observed 

concentration of HEC5725-E-des-chlorophenyl is below 10% of the total applied. This metabolite 

is also observed in the deeper soil layers, but at less than 1% of the total applied. A recently 

submitted aquatic field dissipation study conducted on rice has several deficiencies that limit its use 

for risk assessment purposes at this time; however, the study suggests fluoxastrobin readily 

dissipates from the water column but may persist in sediment. The rapid dissipation of 

fluoxastrobin from the water column is due to partitioning to sediment; however, the role of 

transformation was not investigated. The route of fluoxastrobin dissipation under aquatic field 

conditions could not be determined as soil and water samples were not analyzed for transformation 

products. The total system (water and soil/sediment) half-life as well as residual residues indicate 

fluoxastrobin persists beyond the study duration. This suggests that accumulation (carry over) of 
9

fluoxastrobin in rice paddies is possible. The mobility of fluoxastrobin in the soil profile could not 

be assessed based on the data included in this study.

EXPOSURE MODELING

Aquatic 

For fluoxastrobin use on rice, applications may lead to direct surface water contamination as a 

result of direct spraying of a flooded rice paddy, spray drift or indirect contamination through 

discharge of the paddy water containing soil sorbed fluoxastrobin and dissolved fluoxastrobin. 

Based on the fate properties of fluoxastrobin it may be persistent in the environment for several 

months to more than a year post-application and may accumulate in soil and sediment. There is no 

required water holding period specified on the proposed fluoxastrobin label. 

Fluoxastrobin is stable to hydrolysis and microbial mediated degradation in aquatic environments; 

however, aqueous photolysis is a major route of degradation. The phototransformation of 

fluoxastrobin in water depends on physical characteristics of the water (e.g., sediment loading, 

depth, etc.) which have an effect on sunlight penetration. In general, paddy water is shallow; 

therefore, aquatic photolysis may be a dissipation route for fluoxastrobin. The relatively short water 

column half-life values in both the aquatic field dissipation study and the aqueous photolysis study 

indicate fluoxastrobin may dissipate rapidly from shallow paddy water. Dissipation is primarily due 

to water:sediment partitioning; however, studies have shown that fluoxastrobin water:sediment 

partitioning is variable. Thus, photolysis may play a role in fluoxastrobin dissipation when 

water:sediment partitioning is not rapid. Both laboratory as well as field studies indicate that 

fluoxastrobin may remain in the sediment for more than a year and has the potential to accumulate 

in the sediment.

Analysis Plan

The EFED Tier 1 Rice Model (v1.0, May 8, 2007)6 was used to estimate aquatic exposures for 

applications directly to water (flooded field). The model estimates exposure in a water body

holding a 10 cm water depth. When a pesticide is applied to a water body, the model assumes that it 

will instantaneously partition between a water phase and a sediment phase based on the partition 

coefficient of the chemical. The formula of the Tier I Rice Model v1.0 is as follows:

d

ai

w

K

m

C

0.00105 0.00013

'

and, if appropriate:

Kd = 0.01Koc

where

Cw water concentration (μg/L)

 

6

USEPA 2007. Guidance for Tier I Estimation of Aqueous Pesticide Concentrations in Rice Paddies. Memo from S. 

Bradbury to Environmental Fate and Effects Division; May 8, 2007. U.S. Environmental Protection Agency, Office of 

Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division, 

Washington, DC. Available at http://www.epa.gov/oppefed1/models/water/index.htm#rice (accessed September 27, 

2010).
10

mai’ mass applied per unit area (kg/ha)

Kd water-sediment partitioning coefficient (L/kg)

Koc organic carbon partitioning coefficient (L/kg)

The Tier I Rice Model was calibrated to generate estimates that are similar to or greater than 

dissolved concentrations measured within rice paddies and in discharged paddy water. The 

calibration involved determination of the sediment interaction depth by calibrating the model to 

maximum residues measured in paddy water in dissipation studies. The model does not account for 

pesticide degradation, volatilization, dilution, foliar interception, or other dissipation processes. The 

model was not evaluated or calibrated for concentrations measured in sediment. 

Detailed descriptions and documentation for the Tier I Rice model can be found on the Office of 

Pesticide Program‟s models website.7

Selecting Input Parameters

The input parameters used in this assessment were selected from the environmental fate data 

submitted to support fluoxastrobin registration in accordance with US EPA-OPP EFED water 

model parameter guidance.8The input values used in the Tier I rice model are provided in Table 6.

Table 6. Input Parameters Used in the Rice Model to Estimate Environmental 

Concentrations of Fluoxastrobin

Parameter Values Source

Soil Adsorption 

Coefficient Koc

Rice Model: 848 mL/g mean Koc value MRID 45865315

Surface Water Exposure Estimates

Modeling Data

The proposed use of fluoxastrobin on rice may result in a surface water peak concentration of 93

μg/L.

9

The Tier I Rice Model only provides a single output value; therefore, this value should be 

used for all exposure durations (i.e., peak, 96-hours, 21-day, and 60-day average concentrations). 

The EEC of 93 μg/L for rice is higher than previously reported EDWCs for other fluoxastrobin 

uses. Previous reported estimated environmental concentrations (EECs) were based on Tier II 

surface water modeling (PRZM-EXAMS).

The Tier I rice model does not consider transformation (i.e., anaerobic and aerobic aquatic 

metabolism and aquatic photolysis); fluoxastrobin is only slightly susceptible to metabolism 

(aquatic metabolism total system half-life values 150-190 days) and photolysis in the environment 

 

7

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

8 Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version 

2.1, October 22, 2009.

9 Calculation: 93 μg/L = 0.20 kg a.i./h/[0.00105+0.00013(0.01 x 848)]
11

is assumed to be minimal. Aquatic photolysis may be a major route of fluoxastrobin dissipation in 

the environment; however, aquatic photolysis is assumed to only occur in a small fraction of the 

water column (top few centimeters) and is heavily affected by physical characteristics of the water 

(e.g., sediment loading, depth, etc.) as well as the canopy coverage and water:sediment partitioning. 

A laboratory aquatic photolysis study conducted with natural water indicates fluoxastrobin 

partitions to sediment, limiting photolysis. Aerobic and anaerobic aquatic metabolism studies show 

that fluoxastrobin readily sorbs to sediment in aquatic environments, reducing the water 

concentration rapidly; however, sorption is considered in the Tier I Rice Model; therefore, sorption 

of fluoxastrobin to sediment is reflected in the reported concentration. Therefore, the reported 

EECs are expected to provide a reasonable upper bound concentration for the potential exposure to 

fluoxastrobin in surface water.

Monitoring Data 

Fluoxastrobin is a fairly new chemical so monitoring data is limited. The National Water-Quality 

Assessment Program (NAWQA) database indicates that surface water and bed sediment samples 

were analyzed for fluoxastrobin at two Georgia sites. The fluoxastrobin concentrations were below 

the limits of detections(4.2 ng/L for water and 1.8 μg/kg for sediment). There is no evidence that 

other monitoring sites or programs are looking for or detecting fluoxastrobin in surface water or 

sediment. 

Terrestrial

Terrestrial exposure estimates for avian and mammalian risk assessments were derived using the TREX model (version 1.3.1, December 22, 2006). The EEC values used for terrestrial animal 

exposure are derived from the Kenaga nomograph, as modified by Fletcher et al. (1994), based on a 

large set of actual field residue data. The upper limit values from the nomograph represent the 95th 

percentile of residue values from actual field measurements (Hoerger and Kenaga, 1972). Risk 

quotients are based on the most sensitive LC50 and NOAEC for birds and LD50 for mammals.

We derive terrestrial EECs for fluoxastrobin using the maximum proposed single and annual

application rates (i.e., 2 applications of 0.18 lb a.i./acre made 27 days apart). The default 35-day 

foliar half-life value was used for modeling EECs on terrestrial food items. A complete description 

of the input parameters and output is contained in APPENDIX A. 

ENVIRONMENTAL EFFECTS

Assessment of risk is based on the most sensitive species tested for terrestrial and aquatic 

organisms. The acute and chronic toxicity values for the most sensitive terrestrial and aquatic 

organisms tested are presented in
12

Table 7. These endpoints are based on those presented in the most recent assessment conducted for 

fluoxastrobin (USEPA 2011, D379112+). 
13

Table 7. Toxicity Values Used to Assess Risks from Fluoxastrobin Use

TAXON/SPECIES

ACUTE TOXICITY CHRONIC TOXICITY

Acute Endpoint MRID/

Classification NOAEC 

Affected

Endpoints/

MRID/ 

Classification

Freshwater fish/ 

Rainbow Trout

(Oncorhynchus mykiss)

96-hr LC50 = 0.435

mg a.i./L

458654-14/ 

Acceptable 0.0557 mg a.i./L

No effects at any 

concentration 

tested/458654-20/

Supplemental (no 

LOAEC was 

established)

Freshwater invertebrate/ 

Amphipod

(Gammarus pulex)

48-hr EC50 = 0.12 mg 

a.i./L

460804-02/

Supplemental (the 

study was conducted 

with a non-guideline 

species)

0.045 mg a.i./L

The NOAEC is based 

on an acute-tochronic ratio using

acute/chronic data on 

daphnids

Estuarine/marine fish/ 

Sheepshead minnow

(Cyprinodon variegates)

96-hr LC50 >1.374 mg 

a.i./L

458654-17/

Supplemental1 -- --

Estuarine/marine 

mollusk/ 

Eastern oyster

(Crassostrea virginica)

96-hr EC50 = 0.83 mg 

a.i./L

458654-10/

Supplemental (new 

shell growth did not 

meet minimum 

requirements of 2.0 

mm)

– --

Estuarine/marine 

invertebrate/ 

Mysid shrimp

(Americamysis bahia)

96-hr LC50 = 0.0516

mg a.i./L

458654-11/

Acceptable 0.00061 mg a.i./L

Based on reduced 

survival and 

growth/458654-

19/Supplemental2

Birds/ Northern bobwhite 

quail (Colinus virginianus)

LD50 > 2,000 mg 

a.i./kg-bw

LC50 > 4845 mg 

a.i./kg-diet

458654-22/ 

Acceptable

458654-23/

Acceptable

1029 mg a.i./kgdiet

No effects noted at 

any concentration 

tested/458654-

25/Acceptable

Mammals/ 

Laboratory rat

(Rattus norvegicus)

LD50 > 2,000 mg 

a.i./kg-bw

458656-12/ 

Acceptable 70 mg a.i./kg-bw

Based on reduced 

body weight in adult 

males/458656-

34/Acceptable

Terrestrial invertebrate/ 

Honey bee

(Apis mellifera)

LD50 > 200 μg 

a.i./bee (contact)

458654-27/

Acceptable -- --

Aquatic vascular plant/ 

Duckweed 

(Lemna gibba)

EC50 = 1.2 mg a.i./L

458654-30/ 

Acceptable 0.16 mg a.i./L

Based on reduced 

frond 

number/458654-30/ 

Acceptable
14

TAXON/SPECIES

ACUTE TOXICITY CHRONIC TOXICITY

Acute Endpoint MRID/

Classification NOAEC 

Affected

Endpoints/

MRID/ 

Classification

Aquatic non-vascular 

plant/ 

Green alga

(Selenastrum 

capricornutum)

EC50 = 0.26 mg a.i./L

458654-31/ 

Acceptable 0.076 mg a.i./L

Based on reduced cell 

density/458654-31/ 

Acceptable

Terrestrial plants –

seedling emergence/

Various species

EC25 > 0.54 lb 

a.i./acre

458654-28/ 

Acceptable 0.54 lb a.i./acre

No effects noted at 

the highest 

concentration tested 

(Tier I)/ 458654-28/ 

Acceptable

Terrestrial plants –

vegetative vigor/ Various 

species

EC25 > 0.54 lb 

a.i./acre

458654-28/ 

Acceptable 0.54 lb a.i./acre

No effects noted at 

the highest 

concentration tested 

(Tier I)/ 458654-28/ 

Acceptable

1 Inadequate documentation on solubility of the test substance in the system. The registrant requested that this study 

be upgraded to acceptable; however, the request was denied (see D334233, 2008). No mortality or sublethal effects 

were observed in any control or test group during 96 hours of exposure.

2

Following pairing, male survival data should have been reported; second-generation mysids should have been 

monitored daily for at least 4 days for survival development, and behavior; and terminal growth measurements should 

have been provided in terms of gender.

Aquatic Animals

Fluoxastrobin is highly toxic to freshwater fish and invertebrates; moderately toxic to 

estuarine/marine fish; and very highly toxic to estuarine/marine invertebrates on an acute exposure 

basis. 

No treatment-related effects on hatchability, survival, and/or terminal growth parameters were 

observed in a freshwater fish life-cycle study using fluoxastrobin TGAI and rainbow trout 

(Oncorhynchus mykiss) (MRID 458654-20). The NOAEC was 0.0557 mg a.i./L (the highest 

concentration tested); however, a LOAEC value was not established. Although this study is 

scientifically sound, it was classified as supplemental because a LOAEC value was not determined.

A chronic endpoint is not available for the most acutely sensitive freshwater invertebrate (the 

amphipod, Gammarus pulex). Therefore, a chronic endpoint for freshwater invertebrates is based 

on an ACR using data from daphnids (Daphnia magna). An acute study with TGAI and daphnids 

resulted in an EC50 value of 0.48 mg a.i./L (MRID 458654-06). A life-cycle test using TGAI and 

daphnids (MRID 458654-18) resulted in NOAEC and LOAEC values of 0.18 mg a.i./L and 0.33 

mg a.i./L, respectively, based on reduced reproduction. Therefore, the ACR for daphnids is 2.67 

(0.48/0.18 = 2.67). Applying this ACR to the amphipod acute data, results in a NOAEC of 0.045 

mg a.i./L (0.12/x = 2.67; x = 0.12/2.67 = 0.045).
15

The chronic indoor microcosm study (MRID 464049-01) with the amphipod, G. pulex L., resulted 

in a more sensitive endpoint (15 μg/L) for aquatic invertebrates than that used in this assessment 

(i.e., 45 μg a.i./L). However, the results of a microcosm study are not comparable to submitted 

chronic freshwater invertebrate studies because reproductive endpoints were not measured in the 

microcosm study. A qualitative description of the microcosm study acute endpoints and study 

deficiencies is provided in an EFED Memorandum (USEPA, 2005, D312642) and corresponding 

Data Evaluation Record.

No data are available to assess the chronic toxicity of fluoxastrobin to estuarine/marine fish. 

Because a definitive acute endpoint is not available for estuarine/marine fish, an ACR was not used 

to estimate a NOAEC for this taxon.

One estuarine/marine invertebrate 28-day life cycle test using the TGAI was submitted for 

fluoxastrobin using the mysid shrimp (Americamysis bahia) (MRID 458654-19). All endpoints 

(including survival of first-generation mysids, number of young/female, wet weight, and length of 

surviving first-generation mysids) were affected at all treatment concentrations with the exception 

of the lowest treatment level (0.61 μg a.i./L). The NOAEC and LOAEC values were 0.61 μg a.i./L

and 1.19 μg a.i./L, respectively. This study, although scientifically valid, is classified as 

supplemental because of several deficiencies in monitoring and reporting that are documented in a

previous risk assessment (USEPA, 2004, D289104). 

Terrestrial Animals

Fluoxastrobin is practically non-toxic to birds, mammals, and honeybees on an acute basis. 

The acute oral toxicity of fluoxastrobin to 6-month old bobwhite quail (Colinus virginianus) was 

assessed over 14 days (MRID458654-22). The acute oral LD50 exceeded the highest dose tested 

(>2000 mg a.i./kg bw). There was no mortality or treatment-related effects noted in the study. 

A dietary study with bobwhite quail (MRID 458654-23) resulted in an LC50 greater than the highest 

concentration tested, 4845 mg a.i./kg-diet (there were no mortalities at any test concentration). 

During the 5-day exposure period, treatment-related reductions in percent body weight changes 

were observed at the 2498 and 4845 mg a.i./kg-diet levels, and a treatment-related reduction in food 

consumption was observed at the 4845 mg a.i./kg-diet level. The subsequent NOAEC (based on 

body weight) was 1167 mg a.i./kg-diet for the quail. 

In a mallard duck (Anas platyrhynchos) reproduction study (MRID 458654-26), the NOAEC was 

determined to be 461 mg a.i./kg-diet, based on reduction in female body weight and egg 

production; the LOAEC was 1394 mg a.i./kg-diet. Female body weights, the number of eggs 

laid/hen, and the number of eggs set/hen were all statistically-reduced at the 1,394 mg a.i./kg-diet 

treatment level as compared to the control group. 

Rats exposed to technical grade fluoxastrobin showed no mortality at the highest doses tested. The

LD50 value for the TGAI is >2000 mg a.i./kg-bw (MRIDs 458656-12). 

The NOAEL for rats is 1,000 mg a.i./kg-diet (70 mg a.i./kg-bw) based on decreasing premating 

body weight gain of the P-generation males and females and decreased absolute body weight of the 
16

F1 males and females. The reproductive toxicity NOAEL is 10,000 mg a.i./kg-diet and the 

reproductive toxicity LOAEL is not identified.

Plants

Two Tier II studies of the freshwater aquatic vascular plant, duckweed (Lemna gibba), were 

completed using the TGAI. In both studies (MRIDs 458654-29 and 458654-30), frond number was 

the most sensitive endpoint with EC50 values ranging from 1.2 to 2.9 mg a.i./L. In the study with 

the lowest EC50 value (MRID 458654-30), frond number was significantly reduced at > 0.39 mg 

a.i./L treatment levels; the NOAEC and EC05 values were 0.16 and 0.019 mg a.i./L, respectively. 

Regarding non-vascular aquatic plants, in a Tier II test with freshwater green alga (Selenastrum 

capricornutum) (MRID 458654-31) and the parent form of fluoxastrobin, there were significant 

differences in the cell densities, growth rates, and biomass at all but the lowest treatment levels. 

The EC50, based on cell density, was 0.26 mg a.i./L, and the NOAEC was 0.076 mg a.i./L for all 

endpoints. 

Seedling emergence and vegetative vigor were studied on 10 different species of plants after 

application of the formulated product of fluoxastrobin (HEC 5725 SC 480), at a single 

concentration of 0.54 lb a.i./A (600 g a.i./ha) (MRID 458654-28). No monocot or dicot species was 

significantly affected by the treatment in either study, and no effects exceeded 25%. The respective 

NOAEC and EC25 values are 0.54 and >0.54 lb a.i./A for all tested species. 

Two additional Tier I terrestrial plant studies were recently submitted (MRIDs 48520001 and 

48520002). These studies resulted in EC25 values for seedling emergence and vegetative vigor that 

were greater than the concentration tested (i.e., >2.18 lb a.i./acre). The vegetative vigor study 

(MRID 48520002) is classified as acceptable. The seedling emergence study (MRID 48520001) is 

classified as acceptable except for the results for lettuce, onion, and ryegrass which were 

invalidated due to poor emergence in the study controls (10%, 66%, and 52% emergence, 

respectively). 

RISK CHARACTERIZATION

Aquatic Organisms

The EECs in surface water generated from the Tier I Rice Model represent acute and chronic 

exposure to fish, aquatic invertebrates, and aquatic plants. As shown in Table 8, the acute RQs 

exceed the EPA‟s acute risk LOC of 0.5 for freshwater invertebrates (RQ = 0.78) and 

estuarine/marine invertebrates (RQ = 1.8) (Table 8). The acute restricted use LOC of 0.10 and the 

acute listed species LOC of 0.05 are exceeded for freshwater fish (RQ = 0.21), freshwater 

invertebrates, and estuarine/marine invertebrates. Additionally, the chronic RQs for freshwater fish 

(RQ = 1.7), freshwater invertebrates (RQ = 2.1), and estuarine/marine invertebrates (RQ = 152)

exceed the EPA‟s chronic risk LOC of 1. For aquatic plants, the only RQ that exceeds an EPA LOC 

is for listed non-vascular aquatic plants (RQ = 1.2). Therefore, based on this screening level risk 

assessment, there is a potential risk for freshwater fish and aquatic invertebrates from acute and 

chronic exposures to fluoxastrobin from the new proposed use on rice. Additionally, there is a 
17

potential risk to listed non-vascular aquatic plants (and those listed species that have an obligate 

relationship with non-vascular aquatic plants). 

Table 8. RQs for Aquatic Organisms Exposed to Fluoxastrobin from the Proposed New Use 

on Rice

Taxa EECs

(μg a.i./L)

Acute Endpoint

(LC50 in μg 

a.i./L)

Chronic 

Endpoint 

(NOAEC in μg 

a.i./L)

Acute RQ Chronic 

RQ

Animals

Freshwater Fish

93

435 55.7 0.21 1.7

Freshwater Invertebrate 120 45 0.78 2.1

Estuarine/Marine 

Invertebrate 51.6 0.61 1.8 152

Plants

Taxa EECs (μg 

a.i./L)

Non-listed 

Species 

Endpoint

(EC50 in μg 

a.i./L)

Listed Species 

Endpoint

(NOAEC in μg 

a.i./L)

Non-listed 

Species RQ

Listed 

Species RQ

Vascular Aquatic Plants

93

1,200 160 0.08 0.58

Non-vascular Aquatic 

Plants 260 76 0.36 1.2

Bolded numbers exceed an EPA LOC.

In the estuarine/marine fish acute toxicity study submitted, there were no mortality or sublethal 

effects at the highest treatment levels tested (i.e., the LC50, value is a „greater than‟ value), 

therefore, this endpoint is not used to calculate RQ values. In order to gain a better understanding 

of how the EEC from the proposed fluoxastrobin use on rice relates to the toxicity data currently 

available for estuarine/marine fish, a RQ was calculated using the conservative assumption that the 

highest concentration tested in the study represents the endpoint [i.e., fish LC50 = 1,374 μg a.i./L 

(sheepshead minnow)]. In this exercise, the acute RQ calculated just exceeds the EPA‟s acute LOC 

for listed fish (RQ = 0.07). The actual RQ would be lower than this because no effects were 

observed at the highest treatment levels. There are no chronic toxicity data available for 

estuarine/marine fish, so chronic RQs for this taxon could not be calculated. 

Fluoxastrobin has a borderline high Kow and it is not expected to rapidly degrade via aerobic or 

anaerobic metabolism. Therefore, although it is not expected to bioaccumulate, fluoxastrobin is 

expected to partition to the sediment where it may persist. Accumulation of fluoxastrobin in

sediment is also possible. Due to the toxicity of fluoxastrobin to other aquatic animals, benthic 

organisms may also be at risk from the new proposed use and use patterns. However, toxicity data 

are not available to assess exposure and potential risk to benthic organisms. 

Terrestrial Organisms

None of the RQs for terrestrial animals, based on the results of T-REX (see APPENDIX A), 

exceed any EPA level of concern (LOC) for the new proposed use of fluoxastrobin on rice. 

Because no mortality or sublethal effects were observed at the highest treatment levels tested in the 

avian and mammalian acute studies, standard RQ values for acute exposure could not be calculated 
18

using T-REX. In order to gain a better understanding of how the EECs from the proposed 

fluoxastrobin foliar use on rice relate to the toxicity data currently available for birds and mammals, 

the T-REX model was used to calculate RQs using the conservative assumption that the highest 

values tested in the studies represent endpoints [i.e., avian acute LD50 = 2,000 mg a.i./kg-bw 

(bobwhite quail); avian sub-acute LC50 = 4,845 mg a.i./kg diet (bobwhite quail); mammalian acute 

LD50 = 2,000 mg a.i./kg-bw (rat)]. In this exercise, all of the acute and sub-acute RQs calculated 

using upper bound Kenaga values are below EPA‟s LOCs for all size and dietary classes. The 

actual RQs would be lower than these because no effects were observed at the highest treatment 

levels. 

Risk to non-target insects is not typically estimated in screening-level assessments; however, 

fluoxastrobin is practically non-toxic to adult honeybees, with an LD50 value greater than 200

μg/bee (acute contact toxicity test).

Risks to terrestrial plants are not expected because there were no effects noted in any of the species 

tested in the seedling emergence and vegetative vigor studies at a concentration higher than those 

being proposed for use here [i.e., the NOAEC values (0.54 lb a.i./acre) are higher than the 

maximum single application rate being proposed for rice (0.18 lb a.i./acre)].

Incidents

A search of the Ecological Incident Information System (EIIS, version 2.1), the Avian Incident 

Monitoring System (AIMS)10, and the Incident Data System (IDS) (for aggregate reports) for 

fluoxastrobin was conducted on February 2, 2012. There are currently no reported fluoxastrobin

incidents in these databases. 

Uncertainties and Data Gaps

The following data gaps and uncertainties were identified in this risk assessment:

Environmental Fate:

The route of fluoxastrobin dissipation under aquatic field conditions could not be determined as soil 

and water samples were not analyzed for transformation products. The total system (water and 

soil/sediment) half-life indicates that fluoxastrobin is relatively persistent. In addition, residual 

residues indicate fluoxastrobin persists beyond the study duration. This suggests that accumulation 

(carry over) of fluoxastrobin in rice paddies or other aquatic systems where fluoxastrobin may sorb 

to sediment is possible. 

Ecological Effects: 

The endpoint used to assess acute effects to estuarine/marine fish (OCSPP 850.1075) from 

exposure to fluoxastrobin is based on a study that is classified as supplemental because the 

solubility limit in saltwater (under study conditions) was not determined; therefore, the endpoints 

from the study are potentially based on 'total' concentrations and not necessarily bioavailable 

 

10 http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm
19

concentrations (MRID 458654-17). Therefore, there is some uncertainty regarding the results of 

this study. However, new data are not expected to alter our risk conclusions. Therefore, we do not 

recommend requesting additional data at this time.

A chronic endpoint is not available for the most acutely sensitive freshwater invertebrate (the 

amphipod, Gammarus pulex). Therefore, a chronic endpoint for freshwater invertebrates is based 

on an ACR using data from daphnids (Daphnia magna). 

No data are available to assess the chronic toxicity of fluoxastrobin to estuarine/marine fish. 

Because a definitive acute endpoint is not available for estuarine/marine fish, an ACR could not be 

used to estimate a NOAEC for this taxon. Estuarine/marine fish, based on available data, appear 

less sensitive to fluoxastrobin than freshwater fish (at least on an acute exposure basis). Therefore, 

additional data on estuarine/marine fish are not expected to alter our risk conclusions, and we do 

not recommend requesting these data at this time.

Fluoxastrobin has a borderline high Kow and is not expected to rapidly degrade via anaerobic 

metabolism. Therefore, fluoxastrobin is expected to partition to the sediment where it may persist. 

Due to the toxicity of fluoxastrobin to other aquatic animals, benthic organisms may also be at risk 

from the new proposed use and use patterns. Toxicity data are not available to assess such a risk. 

Therefore, EFED recommends requesting sediment toxicity studies for fluoxastrobin [i.e., Whole 

Sediment: Acute Freshwater Invertebrates (OPPTS 850.1735); Whole Sediment: Acute Marine 

Invertebrates (OCSPP 850.1740); and Whole Sediment: Chronic Invertebrates Freshwater and 

Marine (OCSPP 850.1770; OCSPP 850.1760 or OECD 218]. 

FEDERALLY-LISTED SPECIES

Based on this screening-level assessment, there are potential risks from direct effects to listed and 

non-listed freshwater fish, freshwater invertebrates and estuarine/marine invertebrates and listed 

non-vascular aquatic plants from the new proposed fluoxastrobin rice use. Because of the potential 

risk from direct effects to the listed and non-listed taxa described above, should exposure occur, 

listed species in all taxa may potentially be affected indirectly due to alterations in their habitat 

(e.g., food sources).

To help determine whether sites of pesticide use are geographically associated with known 

locations of listed species [following the convention of the Services, the word „species‟ in this 

assessment may actually apply to a „species‟, „subspecies‟, or an Evolutionary Significant Unit 

(ESU)] a co-location analysis is conducted. At the screening level, this analysis is accomplished 

using the LOCATES (version 2.10.4) database. The database uses location information for listed 

species at the county level and compares it to agricultural census data (from 2002) for crop 

production at the same county level of resolution. The product is a listing of federally-listed species 

that are located within counties known to produce rice. For direct and indirect effects, no taxa could 

be excluded from potential risk (i.e., all taxa are included). 

LOCATES identified a total of 89 listed species that overlapped at the county-level with areas 

where rice is grown (see APPENDIX B for a complete species list). Therefore, at the county-level, 

there is the potential for a total of 89 listed species to be directly and/or indirectly affected by the 
20

proposed fluoxastrobin use on rice. 

This preliminary analysis indicates that there is a potential for the new proposed fluoxastrobin use

on rice to overlap with listed species and that a more refined assessment is warranted. The more 

refined assessment should involve clear delineation of the action area associated with proposed and 

current uses of fluoxastrobin and best available information on the temporal and spatial co-location 

of listed species with respect to the action area. This analysis has not been conducted for this 

assessment.
21

References

USEPA, (2004). New Chemical, Environmental Fate and Effects Science Chapter, Environmental Fate and 

Ecological Risk Assessment for Fluoxatrobin (PC 028869), and End Use Product: HEC 480 SC (40.3% 

active ingredient). Office of Pesticide Programs, United State Environmental Protection Agency, 

Washington, DC. July 27, 2004. D289104. Attached

USEPA, (2005). EFED Review of Fluoxastrobin (EC 100) Chronic Indoor Microcosm Study with the 

Amphipod, Gammarus pulex L.. Office of Pesticide Programs, United State Environmental Protection 

Agency, Washington, DC. September 6, 2005. D312642.

USEPA, (2008). Section 3 Registration for Proposed New Use of Fluoxastrobin on Ornamental Plants. 

Office of Pesticide Programs, United State Environmental Protection Agency, Washington, DC. August 29, 

2008. D349270, D349282.

USEPA, (2008). Response to Comments Concerning the Acceptability of Environmental Fate Studies 

Supporting the Conditions of Registration of Fluoxastrobin (HEC5725), and a Tier I Drinking Water 

Assessment for Uses on Ornamental Plants. Office of Pesticide Programs, United State Environmental 

Protection Agency, Washington, DC. April 2, 2008. D334233, D349285.

USEPA, (2009). Ecological Risk Assessment for the Section 3 New Use Registration of Fluoxastrobin on 

New Food Uses (Berry Subgroup; Field Corn and Soybean; and Sweet Corn and Wheat). Office of 

Pesticide Programs, United State Environmental Protection Agency, Washington, DC. July 17, 2004. 

D356983, D357729, D366187.

USEPA, (2010). Drinking Water Assessment for Fluoxastrobin Use on Squash/Cucumber (Crop Subgroup 

9B) and New In-Furrow and Banded Uses on Tuberous and Corm Vegetables (Crop Subgroup 1C) as Well 

as Peanut. Office of Pesticide Programs, United State Environmental Protection Agency, Washington, DC. 

December 15, 2010. D379114, 384377.
22

Fate MRIDs Cited:

45865304 Hellpointner, E. (1999) Hydrolysis of (Methoxyiminotolyl-Ring-UL-(Carbon 14)) HEC 5725 in 

Sterile Aqueous Buffer Solutions: Lab Project Number: M 1110904-6: MR-058-99: PF-E/MR. 

Unpublished study prepared by Bayer AG. 44 p. 

45865306 Stupp, H. (2001) Photolysis of HEC 5725 in Aqueous Solution: Lab Project Number: MR 072-

00: M 1120905-8. Unpublished study prepared by Bayer AG. 81 p. 

45865403 Schafer, H. (2001) Calculation of a DT-50 Value of HEC5725 Metabolite Oxazepine Generated 

by Photolysis in Aqueous Solution: Lab Project Number: MR-262/0 1: MR262-01: P 668 01 

6521. Unpublished study prepared by Bayer Ag. 16 p. 

45865308 Hellpointner, E. (2001) Photolysis of HEC5725 on Soil Surface: Lab Project Number: M1 

130939-6: MR 347/00. Unpublished study prepared by Bayer AG. 92 p. 

45865309 Brumhard, B.; Eberhardt, R. (2001) Aerobic Degradation of (Methoxyiminotolyl-Ring-UL-

(Carbon 14)) HEC5725 in Soil Laacher Hof AXXa: Lab Project Number: M 125 0886-O: MR 

230/01: THS 4727. Unpublished study prepared by Bayer AG. 58 p. 

45865310 Brumhard, B.; Eberhardt, R. (2001) Aerobic Degradation and Metabolism of 

(Methoxyiminotolyl-Ring-UL-(Carbon 14)-and (Pyrimidine-2-(Carbon 14) HEC5725 in Thre 

Soils: Lab Project Number: M 125 0894-9: MR-231/01: MR-23 1-O 1. Unpublished study 

prepared by Bayer Ag. 124 p. 

45865313 Brumhard, B.; Oi, M. (2002) Aerobic Degradation and Metabolism of (MethoxyiminotolylRing-UL-(Carbon 14)) HEC 5725 in the Water/Sediment System: Lab Project Number: M15 1 

0903-9: MR-396/01: M151 0903-9. Unpublished study prepared by Bayer Ag. 75 p. 

45865312 Hellpointner, E. (2002) Anaerobic Aquatic Degradation and Metabolism of HEC5725: Lab 

Project Number: M152006-3: MR-406/01: HPO-225. Unpublished study prepared by Bayer Ag. 

76 p. 

45865315 Fent, G. (1998) Adsorption/Desorption of (Methoxyiminotolyl-Ring-UL-(Carbon 14)) 

HEC5725 on Four Different Soils: Lab Project Number: BAY27: FM767. Unpublished study 

prepared by Staatliche Lehr-und Forschungsanstalt fuer Landwirtschaft. 46 p. 

45865318 Bauer, M.; Andre, J.; Zielinski, C. (2002) Terrestrial Field Dissipation of HEC 5725 in 

California Soil, 1999: Final Report: Lab Project Number: AG990009: F99568-001: 99.109. 

Unpublished study prepared by Battelle Memorial Institute and Plant Services, Inc. 236 p. 

45865320 Bauer, M.; Andre, J.; Zielinski, C. (2002) Terrestrial Field Dissipation of HEC 5725 in New 

York Soil, 1999: Final Report: Lab Project Number: AG990011: F99565-001: AR99352. 

Unpublished study prepared by Battelle Memorial Institute and A.C.D.S. Research, Inc. 241 p. 

45865323 Bauer, M.; Andre, J.; Zielinski, C. (2002) Terrestrial Field Dissipation of HEC 5725 in 

California Turf, 1999: Final Report: Lab Project Number: AG990014: HC022701: 200219. 

Unpublished study prepared by Battelle Memorial Institute and Plant Sciences, Inc. 253 p. 

45865324 Bauer, M.; Andre, J.; Zielinski, C. (2002) Terrestrial Field Dissipation of HEC 5725 in New 

York Turf, 1999: Final Report: Lab Project Number: AG990015: F99565-001: HC022702. 

Unpublished study prepared by Battelle Memorial Institute and A.C.D.S. Research, Inc. 261 p.
23

48532004 Culligan, J.F. 2009. Aquatic field soil dissipation of Evito 480 SC fungicide following 

application to flooded rice field in Arkansas. Unpublished study performed by G & H 

Associates, Stuttgart, Arkansas; Ag Research Associates, LLC, Sycamore, Georgia and ALS 

Laboratory Group, Edmonton, Alberta, Canada (pp. 1, 7); sponsored and submitted by Arysta 

LifeScience North America, LLC, Cary, North Carolina. Study Number: ARAP-07A-004. 

Experiment initiation June, 2007 (Appendix IV, p. 132) and completion October 8, 2009 

(Appendix III, p. 62). Final report issued October 12, 2009.

Effects MRIDs Cited:

45865422 Barfknecht, R. (2000) HEC 5725 Techn. Ai: Acute Oral Toxicity for Bobwhite Quail: Lab 

Project Number: E 292 1560-5: BAR/LD032. Unpublished study prepared by Bayer Ag. 38 p. 

{OPPTS 850.2100} 

45865423 Barfknecht, R. (2001) HEC 5725 Techn.: 5-Day Dietary LC50 for Bobwhite Quail (Colinus 

virginianus): Lab Project Number: E 295 1558-5: BAR/LC007. Unpublished study prepared by 

Bayer Ag. 34 p. {OPPTS 850.2200} 

45865425 Frieling, W. (2001) Reproduction Study in Bobwhite Quail with HEC 5725 Techn.: (By Dietary 

Admixture): Lab Project Number: 259774. Unpublished study prepared by Notox B.V. 211 p. 

{OPPTS 850.2300} 

45865414 Dorgerloh, M. (1999) HEC 5725 Acute Toxicity (96 Hours) to Rainbow Trout (Oncorhynchus 

mykiss) in a Static Test: Lab Project Number: E 250 1605-9: DOMA 99065: 00579. 

Unpublished study prepared by Bayer Ag. 48 p. {OPPTS 850.1075} 

45865406 Heimbach, F. (1999) Acute Toxicity of HEC 5725 (tech.) to Water Fleas (Daphnia magna): Lab 

Project Number: HBF/DM 211: E 320 1674-3. Unpublished study prepared by Bayer Ag. 47 p. 

{OPPTS 850.1010} 

45865410 Ward, T.; Wyskiel, D.; Boeri, R. (2002) HEC 5725: A 96-Hour Shell Deposition Test with the 

Eastern Oyster (Crassostrea virginica): Lab Project Number: 99-B-133: HC831501: 2357-BR. 

Unpublished study prepared by T.R. Wilbury Laboratories, Inc. 30 p. 

45865411 Boeri, R.; Wyskiel, D.; Ward, T. (2002) HEC 5725: A 96-Hour Flow-Through Acute Toxicity 

Test with the Saltwater Mysid, (Americamysis bahia): Lab Project Number: 99-B-131: 

HC833101: 2358-BR. Unpublished study prepared by T.R. Wilbury Laboratories, Inc. 31 p. 

45865417 Kern, M.; Woodard, D.; Mattern, G. (2002) Acute Toxicity of HEC 5725 (Technical) to the 

Sheepshead Minnow (Cyprinodon variegatus) Under Static Conditions: Lab Project Number: 

HC830901: 110322. Unpublished study prepared by Bayer CropScience. 30 p. 

45865418 Hendel, B. (2000) Influence of HEC 5725 (tech.) on the Reproduction Rate of Water Fleas 

(Daphnia magna): Lab Project Number: E 321 1798-1: HDB/RDM 64. Unpublished study 

prepared by Bayer Ag. 80 p. {OPPTS 850.1300} 

45865419 Ward, T.; Wyskiel, D.; Boeri, R. (2002) HEC 5725: A Flow-Through Life Cycle Toxicity Test 

with the Saltwater Mysid (Americamysis bahia): Lab Project Number: 99-B-132: HC843101: 

2359-BR. Unpublished study prepared by T.R. Wilbury Laboratories, Inc. 48 p. 

45865420 Scheerbaum, D. (2001) HEC 5725--Fish (Rainbow Trout), Early-Life Stage Toxicity Test, Under 

Flow-Through Conditions: (Final Report): Lab Project Number: 991028BD: FSR69122. 

Unpublished study prepared by Dr. U. Noack-Laboratorium. 84 p. {OPPTS 850.1400} 
24

45865612 Krotlinger, F. (1996) HEC 5725: Study for Acute Oral Toxicity in Rats: Lab Project Number: 

25231: T8060660: 109158. Unpublished study prepared by Bayer Ag. 29 p. {OPPTS 870.1100} 

45865634 Young, A.; Christenson, W. (2001) A Two-Generation Reproductive Toxicity Study with HEC 

5725 in the Wistar Rat: Lab Project Number: 99-R72-BW: 110249. Unpublished study prepared 

by Bayer Corporation and Pathology Associates International. 1473 p. {OPPTS 870.3800} 

45865428 Bowers, L. (2003) Tier 1 Seedling Emergence and Vegetative Vigor Nontarget Phytotoxicity 

Study Using HEC 5725 SC 480: Lab Project Number: 200313: HC451601: HC451602. 

Unpublished study prepared by Bayer CropScience. 97 p. 

45865430 Kern, M.; Lam, C. (2002) Toxicity of HEC 5725 Technical to Duckweed (Lemna gibba G3): 

Lab Project Number: HC883701: 200340. Unpublished study prepared by Bayer CropScience. 

36 p. {OPPTS 850.4400} 

45865431 Dorgerloh, M. (2000) HEC 5725--Influence on the Growth of the Green Alga, Selenastrum 

capricornutum: Lab Project Number: E 323 1609-4: DOM 99061. Unpublished study prepared 

by Bayer Ag. 38 p. {OPPTS 850.5400} 

45865427 Bruhnke, C. (2000) HEC 5725 A.I.--Acute Effects on the Honeybee Apis mellifera 

(Hymenoptera, Apidae); Limit Test: Lab Project Number: 990222BN: IBA64041. Unpublished 

study prepared by Noack-Laboratorium. 30 p. {OPPTS 850.3020} 

46080402 van Wijngaarden, R.; (2003) Acute Toxicity of Fluoxastrobin to Freshwater Invertebrates: Final 

Report. Project Number: ALT/RW/2003/1, ALTERRA/RW/2003/1. Unpublished study prepared 

by Alterra, Green World Research. 93 p.

46404901 Liebig, M. (2003) A Long-Term Indoor Microcosm Study on the Toxicity of Fluoxastrobin (EC 

100) to the Amphipod Gammarus pulex L. in a Natural Water-Sediment System. Project 

Number: P1MG. Unpublished study prepared by ECT Oekotoxikologie Gmbh. 135 p.
25

APPENDIX A

T-REX Input and Output Parameters for the Proposed New Use of Fluoxastrobin on Rice.

Input Parameters

Chemical Name: Fluoxastrobin

 Use Rice

Application Rate 0.18 lb a.i./acre

Half-life 35 days 

Application Interval 27 days

Maximum # Apps./Year 2

Length of Simulation 1 year

Endpoints

Avian

Mallard duck LD50 (mg/kg-bw) 2000.00

Bobwhite quail LC50 (mg/kg-diet) 4845.00

Mallard duck NOAEL(mg/kg-bw) 0.00

Bobwhite quail NOAEC (mg/kg-diet) 1029.00

Mammals

LD50 (mg/kg-bw) 2000.00

LC50 (mg/kg-diet) 0.00

NOAEL (mg/kg-bw) 70.00

NOAEC (mg/kg-diet) 1000.00

Output Parameters

Dietary-based EECs (ppm) Kenaga

Values

Short Grass 69

Tall Grass 31

Broadleaf plants/sm Insects 39

Fruits/pods/seeds/lg insects 4.3
26

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs

Upper Bound Kenaga, Acute Avian Dose-Based Risk Quotients

Size 

Class

(grams)

Adjusted

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 2000.00 78.02 0.04 35.76 0.02 43.89 0.02 4.88 0.00 1.08 0.00

100 2000.00 44.49 0.02 20.39 0.01 25.03 0.01 2.78 0.00 0.62 0.00

1000 2000.00 19.92 0.01 9.13 0.00 11.20 0.01 1.24 0.00 0.28 0.00

Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50

EECs and RQs

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

4845 68.51 0.01 31.40 0.01 38.54 0.01 4.28 0.00

Size class not used for dietary risk quotients

Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

NOAEC 

(ppm)

EECs and RQs

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

1029 68.51 0.07 31.40 0.03 38.54 0.04 4.28 0.00

Size class not used for dietary risk quotients

Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients 

Size 

Class

(grams)

Adjusted

LD50

EECs and RQs

Short Grass Tall Grass Broadleaf Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 4395.66 65.32 0.01 29.94 0.01 36.74 0.01 4.08 0.00 0.91 0.00

35 3556.56 45.14 0.01 20.69 0.01 25.39 0.01 2.82 0.00 0.63 0.00

1000 1538.32 10.47 0.01 4.80 0.00 5.89 0.00 0.65 0.00 0.15 0.00

Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC 

(ppm)

EECs and RQs

Short Grass Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

1000 68.51 0.07 31.40 0.03 38.54 0.04 4.28 0.00

Size class not used for dietary risk quotients
27

Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients

Size 

Class

(grams)

Adjusted 

NOAEL

EECs and RQs

Short Grass Tall Grass Broadleaf Plants/

Small Insects

Fruits/Pods/

Seeds/

Large Insects

Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 153.85 65.32 0.42 29.94 0.19 36.74 0.24 4.08 0.03 0.91 0.01

35 124.48 45.14 0.36 20.69 0.17 25.39 0.20 2.82 0.02 0.63 0.01

1000 53.84 10.47 0.19 4.80 0.09 5.89 0.11 0.65 0.01 0.15 0.00
28

APPENDIX B

List of Listed Species that Overlap at the County Level with Rice

Inverse Name Species Taxon 

Frog, California Red-legged Rana aurora draytonii Amphibian 

Salamander, California Tiger Ambystoma californiense Amphibian 

Toad, Houston Bufo houstonensis Amphibian 

Crane, Whooping Grus americana Bird 

Mucket, Pink (Pearlymussel) Lampsilis abrupta Bivalve 

Mussel, Scaleshell Leptodea leptodon Bivalve 

Mussel, snuffbox Epioblasma triquetra Bivalve 

Mussel, Winged Mapleleaf Quadrula fragosa Bivalve 

Pearlshell, Louisiana Margaritifera hembeli Bivalve 

Pearlymussel, Curtis' Epioblasma florentina curtisii Bivalve 

Pearlymussel, Fat Pocketbook Potamilus capax Bivalve 

Rock-pocketbook, Ouachita (=Wheeler's 

pm) Arkansia wheeleri Bivalve 

Crayfish, Shasta Pacifastacus fortis Crustacean 

Fairy Shrimp, Conservancy Fairy Branchinecta conservatio Crustacean 

Fairy Shrimp, Longhorn Branchinecta longiantenna Crustacean 

Fairy Shrimp, Vernal Pool Branchinecta lynchi Crustacean 

Shrimp, California Freshwater Syncaris pacifica Crustacean 

Tadpole Shrimp, Vernal Pool Lepidurus packardi Crustacean 

Adobe Sunburst, San Joaquin Pseudobahia peirsonii Dicot 

Allocarya, Calistoga Plagiobothrys strictus Dicot 

Aster, Decurrent False Boltonia decurrens Dicot 

Bird's-beak, Palmate-bracted Cordylanthus palmatus Dicot 

Bird's-beak, Soft Cordylanthus mollis ssp. mollis Dicot 

Butterweed, Layne's Senecio layneae Dicot 

Catchfly, Spalding's Silene spaldingii Dicot 

Chaffseed, American Schwalbea americana Dicot 

Checker-mallow, Keck's Sidalcea keckii Dicot 

Clover, Fleshy Owl's Castilleja campestris ssp. succulenta Dicot 

Clover, Running Buffalo Trifolium stoloniferum Dicot 

Dawn-flower, Texas Prairie (=Texas 

Bitterweed) Hymenoxys texana Dicot 

Evening-primrose, Antioch Dunes Oenothera deltoides ssp. howellii Dicot 

Evening-primrose, San Benito Camissonia benitensis Dicot 

Fiddleneck, Large-flowered Amsinckia grandiflora Dicot 

Fruit, Earth (=geocarpon) Geocarpon minimum Dicot 

Golden Sunburst, Hartweg's Pseudobahia bahiifolia Dicot 

Goldfields, Contra Costa Lasthenia conjugens Dicot 

Gourd, Okeechobee Cucurbita okeechobeensis ssp. Dicot 
29

Inverse Name Species Taxon 

Grass, Hairy Orcutt Orcuttia pilosa Dicot 

Grass, Sacramento Orcutt Orcuttia viscida Dicot 

Grass, Slender Orcutt Orcuttia tenuis Dicot 

Jacquemontia, Beach Jacquemontia reclinata Dicot 

Jewelflower, California Caulanthus californicus Dicot 

Meadowfoam, Butte County Limnanthes floccosa ssp. californica Dicot 

Milk-vetch, Clara Hunt's Astragalus clarianus Dicot 

Navarretia, Few-flowered Pauciflora Navarretia leucocephala ssp. Dicot 

Paintbrush, Tiburon Castilleja affinis ssp. neglecta Dicot 

Pawpaw, Four-petal Asimina tetramera Dicot 

Phlox, Texas Trailing Phlox nivalis ssp. texensis Dicot 

Polygala, Tiny Polygala smallii Dicot 

Pondberry Lindera melissifolia Dicot 

Potato-bean, Price's Apios priceana Dicot 

Pussypaws, Mariposa Calyptridium pulchellum Dicot 

Sand-verbena, Large-fruited Abronia macrocarpa Dicot 

Spurge, Hoover's Chamaesyce hooveri Dicot 

Thistle, Suisun Cirsium hydrophilum var. Dicot 

Tuctoria, Green's Tuctoria greenei Dicot 

Woolly-threads, San Joaquin Monolopia (=Lembertia) congdonii Dicot 

Goby, Tidewater Eucyclogobius newberryi Fish 

Salmon, Chinook Oncorhynchus (=Salmo) tshawytscha Fish 

Salmon, Coho Oncorhynchus (=Salmo) kisutch Fish 

Sawfish, Smalltooth Pristis pectinata Fish 

Smelt, Delta Hypomesus transpacificus Fish 

Steelhead Oncorhynchus (=Salmo) mykiss Fish 

Sturgeon, Gulf Acipenser oxyrinchus desotoi Fish 

Sturgeon, North American green Acipenser medirostris Fish 

Sturgeon, Pallid Scaphirhynchus albus Fish 

Sucker, Modoc Catostomus microps Fish 

Trout, Bull Salvelinus confluentus Fish 

Trout, Lahontan Cutthroat Oncorhynchus clarki henshawi Fish 

Trout, Paiute Cutthroat Oncorhynchus clarki seleniris Fish 

Beetle, Delta Green Ground Elaphrus viridis Insect 

Dragonfly, Hine's Emerald Somatochlora hineana Insect 

Cladonia, Florida Perforata Cladonia perforata Lichen 

Bat, Gray Myotis grisescens Mammal

Bat, Indiana Myotis sodalis Mammal 

Bat, Ozark Big-eared 

Corynorhinus (=Plecotus) townsendii 

ingens Mammal 

Manatee, West Indian Trichechus manatus Mammal 

Mouse, Southeastern Beach Peromyscus polionotus niveiventris Mammal 
30

Inverse Name Species Taxon 

Whale, Gray Eschrichtius robustus Mammal 

Bluegrass, Napa Poa napensis Monocot 

Grass, Colusa Neostapfia colusana Monocot 

Grass, San Joaquin Valley Orcutt Orcuttia inaequalis Monocot 

Grass, Solano Tuctoria mucronata Monocot 

Ladies'-tresses, Navasota Spiranthes parksii Monocot 

Ladies'-tresses, Ute Spiranthes diluvialis Monocot 

Seagrass, Johnson's Halophila johnsonii Monocot 

Alligator, American Alligator mississippiensis Reptile 

Crocodile, American Crocodylus acutus Reptile 

Snake, Giant Garter Thamnophis gigas Reptile