UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF 

CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

PC Code: 129223 

Chemical: Sedaxane 

DP Barcode: 405155; 

407045 

March 21, 2013 

MEMORANDUM 

SUBJECT: 

TO: 

FROM: 

THROUGH: 

Ecological Risk Assessment for New Seed Treatment Uses of Sedaxane including 

Corn, Sorghum, Dried Shelled Peas and Beans, Chickpeas, Lentils and Fava 

beans, Rapeseed subgroup and Potato Pieces. PC Code: 129223; DP Barcode: 

405155,407045 

Heather Garvie, Reviewer 

Cynthia Giles-Parker, Chief 

Herbicide Branch 

Registration Division (7505P) 

Amy Blankinship, Chemist J. r;/Z._t.;. ~ /' //71- :.A 

James Hetrick, Ph.D., SeniorL§~st ,...:_;~ t/. rr~ I 

Rochelle Bohaty, Ph.D., Chemist 

Environmental Risk Branch III 

Environmental Fate and Effects Division (7507P) 

Dana 

Rosanna 

Spatz, 

Louie

Branch 

-Juzwiak, 

Chie~ RAPL . 

Environmental Risk Branch: 

Environmental Fate and Effects Division (7507P) 

The registrant, Syngenta Crop Protection, Inc. is requesting to revise the Vibrance (EPA Reg. 

No.100-1374; 45.45% sedaxane) label to add the following proposed seed treatment uses: dried 

shelled peas and beans; chickpeas; lentils and fava beans; sorghum, rapeseed subgroup 

(including canola), corn, and potato. 

I. Executive Summary 

The registrant, Syngenta Crop Protection, Inc. is requesting to revise the Vibrance (EPA Reg. 

No.1 00-1374; 45.45% sedaxane) label to add the following proposed seed treatment uses: dried 

shelled peas and beans; chickpeas; lentils and fava beans; sorghum, rapeseed subgroup 

(including canola), corn and potato. 

1 

' 
2

The likelihood of acute and chronic risk to freshwater and estuarine/marine fish and 

invertebrates, freshwater amphibians, and aquatic plants from exposure to sedaxane from the 

proposed uses is anticipated to be low as the calculated RQ values for each taxa did not exceed 

the level of concern (LOC). 

For birds/terrestrial-phase amphibians/reptiles, there were no mortalities in any of the available 

acute and subacute avian studies. No RQs were calculated; however, based on a comparison of 

the calculated EECs and the highest concentration tested, acute risk to non-listed and listed birds 

(surrogates for terrestrial-phase amphibians and reptiles) and mammals is anticipated to be low. 

Chronic avian RQs did not exceed the LOC. For mammals, neither the acute or chronic RQs 

exceeded the LOC. 

The terrestrial plant RQs did not exceed the LOC. 

II. Analysis 

A. Use Characterization 

The proposed changes to Vibrance (EPA Reg. No. 100-1374) label is to add uses for seed 

treatment to dried shelled peas and beans; chickpeas; lentils and fava beans; sorghum, rapeseed 

subgroup (including canola) and corn. Treatment to potato pieces is also included on the 

proposed label. 

Sedaxane is a pyrazole-carboxamide fungicide within the anilide fungicide chemical class and is 

currently registered as a seed treatment. Sedaxane was recently registered in the United States as 

a seed treatment for small grain cereals (barley, wheat, oats, rye and triticale), soybean and 

canola to protect against certain soil-borne and seed-borne diseases. Target fungal pathogens for 

sedaxane include: Fusarium Spp. Pythium spp., Septoria, smut (Ustilago tritici), stink bunt 

(Tilletia caries), loose smut (Ustilago nuda), head smut (Sphacelotheca reiliana) and 

Rhizoctonia spp. In addition to the technical product, three end use products were registered. 

Two of the proposed end use products contain a combination of multiple pesticide active 

ingredients, including difenoconazole, mefenoxam and thiamethoxam. These uses are considered 

widespread. 

 

According to the proposed label, sedaxane would be applied as a water-based slurry to seeds 

which are then planted according to planting practices employed for the respective crops to 

provide protection against certain seed-born and soil-born diseases. The label does not mention 

the use of a sticker agent and as such there may be an increased likelihood of creating dust from 

abraded seed coatings. 

The application rates for each of the proposed uses (dried shelled peas and beans; chickpeas; 

lentils and fava beans; sorghum; rapeseed subgroup (including canola); corn; and potato) are 

provided in Table 1. For potato, the proposed label is that a single application rate resulting in 

0.1 lb a.i./A, using the maximum application rate of 0.08 fl oz. product/100 seed, can be applied 

once every other year. To achieve 0.1 lb a.i./A using the labeled application rate to 100 lb seed, a 
3

maximum seeding rate (lb seed/A) was calculated. Based on information provided by the 

registrant, the optimal size of a potato piece is 2.25 oz, with a maximum size of 2.5 oz.1. If using 

the calculated seeding rate (3,333 lb seed/A) and the optimal size, this equates to 23,701 potato 

pieces per acre. This should represent a high-end estimate of the number of potential potato 

pieces in an acre based on information presented by the registrant. 

 

Label considerations 

On page ten of the proposed VibranceTM label (EPA Reg. No. 100-1374) for potato converting 

the use rate to pounds a.i. per 100 pounds seed (lb a.i./100 lb seed) results in slightly different 

values when using the two use rate methods proposed on the label. If calculating a “lb a.i./100 lb 

seed” use rate using the proposed label rate of 0.08 fl oz product/100 lb seed, then the resulting 

value is 0.0026875 lb a.i./100 lb seed. If the labeled use rate of 2.5 g a.i./100 kg seed is used to 

convert to pounds, then the value is 0.00250 lb a.i./100 lb seed. As the fluid ounce rate resulted 

in a high application rate, this rate was modeled. This slight difference in values also occurs in 

the other labeled uses as well which represents the low end range of the labeled application rate. 

 

1

 Letter addressed to Ms. Heather Garvie, OPP, U.S. EPA from John Keeling of the National Potato Council. Dated 

January 29, 2013. 
4

Table 1. Proposed Sedaxane Application Rates 

Crop 

Maximum 

Application Rate 

lb a.i. 

/100 lb of seed 

Maximum 

Seeding Ratea 

lb seed /A 

Maximum Single 

Application Rate 

lb a.i./A 

(kg a.i./ha) 

Maximum Total 

Application Rate 

Maximum Number 

of Applications

MRI (d)c 

Per Year lb a.i./A Per CCb lb a.i./A Per Year lb a.i./A Per CCb lb a.i./A 

corn 0.04 33e 0.013 (0.015) 0.026 0.026 2 2 3

dried shelled 

pea and bean 

(subgroup 6C; 

except soybean) 

0.005 42f 0.002 (0.002) 0.004 0.004 2 2 3

rapeseed 

(subgroup 20A 

including 

canola) 

0.005 5 0.0003 (0.0003) 0.006 0.006 2 2 30

sorghum 0.005 9 0.0046 (0.0052) 0.0092 0.0092 2 2 3

potato 0.003 3333g 0.1 (0.11) 0.1 0.1 1 1 N

a. The maximum seeding rate was developed based on data provided by BEAD—J. Becker; S. Ratnayake. Acres Planted per Day and Seeding 

in the United States, March 24, 2011. 

b. Reported as per crop cycle or per season on label(s). c. MRI – Minimum retreatment interval d. The minimum planting depth was taken from the USDA’s National Information System for the Regional IPM Centers crop profiles. Bracket

crop profile the value was taken from. 

e. Sweet corn [59,739 seeds/A; 1,800 seeds/lb] f. Southern pea [139,392 seeds/A; 3,200 seeds/lb] g. Rate determined by calculating the necessary lb seed/A to achieve an eventual maximum single application rate of 0.1 lb a.i./A using the pro

application rate of 0.003 lb a.i./100 seed (0.08 fl oz product/100 lb seed) 

h. Except canola 
5

B. Environmental Fate Summary 

Environmental transformation of sedaxane follows two pathways (see D405391 and 407956 for 

more details). Laboratory data indicate that in the environment sedaxane is persistent (Table 2). 

Sedaxane is only susceptible to degradation via aerobic soil metabolism. Laboratory half-life 

values for aerobic soil metabolism are 296-400 (soil) days based on single first order (SFO) 

kinetics; however, aerobic biodegradation of sedaxane in soil does not follow single first order 

kinetics (SFO). In general, sedaxane concentrations decrease over the first 100 days 

(approximate); however, after 100 days, sedaxane concentrations remain steady (approximately 

50% of the applied radioactivity) through study termination (≥365 days). Additional kinetic 

analysis using Nth-Order Rate Model or Indeterminate Order Rate Equation (IORE) and Double 

First-Order in Parallel (DFOP) models resulted in representative half-lives >100 days (often 

>365 days).2

 Sedaxane photolysis studies (laboratory half-life of 46 days for aqueous photolysis 

and 253 days for soil photolysis)3

 also suggest sedaxane is persistence in the environment. 

Hydrolysis, anaerobic soil and aquatic transformation, and aerobic aquatic metabolism are not 

expected to contribute to the dissipation of sedaxane in the environment. Terrestrial field 

dissipation data (DT50 value 114-132 days) suggest sedaxane will persist in the environment 

consistent with laboratory metabolism and photolysis data. 

Trans- and cis- isomers of sedaxane show comparable degradation rates in soil; however, only a 

few submitted studies distinguish the two isomers. There is one aerobic soil metabolism study 

that contains both data for sedaxane degradation after direct soil application, as well as soil 

dissipation and transformation data following soil incorporation of sedaxane treated seeds. In 

addition, the registrant submitted several additional aerobic soil dissipation studies that explored 

the dissipation of sedaxane after planting of treated seeds. While seed treatment studies represent 

the intended use pattern and permit the identification of potential environmental transformation 

products, these studies do not permit the calculation of an aerobic soil metabolism rate (or 

corresponding half-life values), as other dissipation mechanisms may occur [i.e., plant uptake in 

roots or shoots (shoots were analyzed in the submitted studies; however, the roots were analyzed 

as part of the soil matrix), or chemical sorption to seed coat] which cannot be parsed out due to 

the study design. In addition, a large amount of unextracted residues further complicates the 

interpretation of the seed studies. The amount of unextracted residues increases throughout the 

study. Despite these complications, these aerobic dissipation/degradation studies suggest that 

metabolism of sedaxane in soil is faster [laboratory half-life values of 88-181 days (seed)] in the 

presence of germinating seed. This is supported by known literature that describes the influence 

of plant roots and germinating seeds on microbial activity in the rhizosphere. 

 

2

 “Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media” Health Canada, U.S. 

Environmental Protection Agency, December 2011 

3

 The photolysis half-lives were calculated based on the assumption that the average daily solar radiation is 

approximately 75% of the maximum intensity over a 12 hour period. This was taken into account in the comparison 

of the artificial light source and that of natural summer sunlight, conducted by the study authors. Because solar 

intensity of natural summer sunlight is likely not 100% during a 12 hour period, and because the sedaxane is 

proposed as a seed treatment and likely incorporated in the soil, the reviewers did not adjust the half-life values to 

represent 100% soil radiation over the 12 hour period. 
6

Table 2. Chemical Properties and Environmental Fate Parameters of Sedaxane

Parameter Value Source/Classification 

(Comments)

Selected Physical/Chemical Parameters 

Molecular formula C18H19F2N3O Calculated 

using ChemDraw 

Molecular weight 331.37 g/mol Calculated 

using ChemDraw 

Vapor pressure 

20C 6.5 x 10-8 Pa 

1.3 x 10-9 atm 

25C 1.7 x 10-7 Pa 

1.3 x 10-9 mm Hg 

4.9 x 10-10 atm 

MRID 47473326 

Aqueous solubility at 25 C pH 

6.5 14 mg/L MRID 47473326 

Henry’s Law Constant 

calculated based on 14 g/m3

 

and 1.7 x 10-7 Pa at 25 C pH 

6.5 

4.0 x 10-6 Pa m3

/mol 

3.95 x 10-11 atm-m3

/mol 

MRID 47473326 

Calculated 

Log octanol-to-water partition 

coefficient (log KOW) 

at 25°C pH 6.67 

3.3 (KOW=2100) MRID 47473326 

Dissociation constant (pKa) None (pH 1-12) MRID 47473326 

Transformation Mechanisms1,2

Hydrolysis half-life 

at 20C and 50C 

No substantial degradation 

(pH 4, 7, and 9) 

MRID 47473318/ 

Acceptable 

Aqueous photolysis half-life at 

25C 46 days (identified parent only)

MRID 47473319/ 

Upgradable 

(up to 20% of the extracted residues 

were not identified) 

Soil photolysis half-life at 

20C 

253 days (average value)

213 days (pyrazole-label)

292 days (phenyl-label) 

MRID 47473446/ 

Supplemental 

MRID 47473447/ 

Supplemental 

Aerobic soil metabolism halflife at 20°C 

71days (SFO DT50) 

IORE DT50= 63 d; DT90= 400 d; 

tR IORE = 120 d (Gatrenacker loam) 

extracted parent from seed studies

*observed: DT50= 62-84 days DT 90=not observed 

MRID 47473444/ 

Supplemental 

(high application rate; seed treatment)

71 days (SFO DT50)3

IORE DT50= 44 d; DT90= 883 d; 

tR IORE = 266 d (Marsillargues silty clay) 

extracted parent from seed studies

*observed: DT50= 27-49 days DT 90=not observed 

MRID 47473445/ 

Supplemental 

(high application rate; seed treatment)
7

Parameter Value Source/Classification 

(Comments)

54 days (SFO DT50)3

SFO DT50= 64 d; DT90= 212 d; 

SFO tR = 64 d (Gartenacker loam)

extracted parent from seed studies

*observed: DT50= 27-81 days DT 90=123-365 

78 days (SFO DT50) 

SFO DT50= 78 d; DT90= 258 d; 

SFO tR = 78 d (Paperlacker loamy sand) 

extracted parent from seed studies

*observed: DT50= 27-81 days DT 90=not observed 

95 (SFO DT50) 

IORE DT50= 83 d; DT90= 8504 d; 

tR IORE = 2560 d (18 acres sandy clay) 

extracted parent from seed studies

*observed: DT50= 81-123 days DT 90=not observed 

87 days (SFO DT50) 

SFO DT50= 87 d; DT90= 288 d; 

SFO tR = 78 d Gartenacker loam) 

extracted parent from seed studies

*observed: DT50= 31-50 days DT 90=237-365 

MRID 47473448/ 

Supplemental 

[high application rate; high levels of 

unextracted residues; some studies 

were conducted on treated seeds; halflife values are calculated well beyond 

the study termination (up to 365 days)]

78 days (SFO DT50) 

IORE DT50= 34 d; DT90= 3763 d; 

tR IORE = 1130 d (California sand) 

extracted parent from seed studies

*observed: DT50= 31-81 days DT 90=not observed 

133 days [average of 105 (SFO DT50; phenyl) and 160 

(SFO DT50; pyrazole) days] 

DFOP DT50= 49 d; DT90= 894 d; 

DFOP Slow t1/2 = 373 d (North Dakota clay loam, 

pyrazole) 

extracted parent from seed studies

*observed: DT50= 80-122 days DT 90=not observed 

DFOP DT50= 42.4 d; DT90= 1094 d; 

DFOP Slow t1/2 = 544 d (North Dakota clay loam, phenyl)

extracted parent from seed studies

*observed: DT50= 31-50 days DT 90=not observed 

tR DFOP Slow t1/2 = 459 d (average of both labels) 

296 days (SFO DT50) 

DFOP DT50= 222 d; DT90= 3005 d; 

DFOP Slow t1/2 = 1200 d (Gartenacker loam) 

extracted parent from soil studies

*observed: DT50= 241-367 days DT 90=not observed 
8

Parameter Value Source/Classification 

(Comments)

373 days (SFO DT50)3

DFOP DT50= 423 d; DT90= 3376 d; 

DFOP Slow t1/2 = 1270 d (California sand) 

extracted parent from soil studies

*observed: DT50= 241->367 days DT 90=not observed 

400 days [average of 422 (SFO DT50;phenyl) and 377 

(SFO DT50;pyrazole) days] 

DFOP DT50= 98 d; DT90= >>365 d; 

DFOP Slow t1/2 = 1280 d (North Dakota clay loam, 

pyrazole) 

extracted parent from soil studies

*observed: DT50= 80-122 days DT 90=not observed 

DFOP DT50= 437 d; DT90= 2306 d; 

DFOP Slow t1/2 = 805 d (North Dakota clay loam, phenyl)

extracted parent from soil studies

*observed: DT50= 241-367 days DT 90=not observed 

tR DFOP Slow t1/2 = 1043 d (average of both labels) 

Aerobic aquatic metabolism 

half-life (20C) 

849 (river; SFO DT50) and 920 (pond; SFO DT50) days 

(whole system) 

MRID 47473468/ 

Supplemental 

[high application rate; >10% applied 

radioactivity present as unextracted 

residues; half-life values are calculated 

well beyond the study termination (360 

days)] 

Anaerobic soil metabolism 

half-life (20C) 

375 days 

**dissipation half-life of extracted parent from seed 

studies** 

MRID 47473443/ 

Supplemental 

[high application rate; >10% applied 

radioactivity present as unextracted 

residues; study was conducted on 

treated seeds; half-life values are 

calculated well beyond the study 

termination (123 days)] 

Anaerobic aquatic metabolism 

half-life (20C) 

4693 (river; SFO DT50) and 1970 (pond; SFO DT50) 

days (whole system) 

MRID 47473468/ 

Supplemental 

[high application rate; >10% applied 

radioactivity present as unextracted 

residues; half-life values are calculated 

well beyond the study termination (360 

days)] 

Mobility

Range of Freundlich soil-water 

partition coefficients (KF); 

1/n value; and 

Freundlich organic carbonnormalized coefficients (KFOC) 

6.7, 2.8, 16.3, 3.1, 2.0, and 12.9 L/kg-soil; 

0.81, 0.85, 0.90, 0.92, 0.87, and 0.83; and 

256.6, 268.5, 587.5, 584.9, 662.5, and 528.9 mL/gOC 

MRID 47473461/ 

Acceptable 
9

Parameter Value Source/Classification 

(Comments)

Field Dissipation 

Terrestrial field dissipation 

half-life 

Washington loamy sand: 31 days 

North Dakota sandy loam: 95 days 

California sandy loam: 31 days 

(seed studies) MRID 47473453/ 

Supplemental Washington loamy sand (in furrow 1.5 g/ha): 119 days 

Washington loamy sand (in furrow 91 g/ha): 132 days 

(soil studies) 

France silt loam: 119 days 

Italy silty clay loam: 131 days 

(seed studies) 

MRID 47473454/ 

Supplemental 

1. Reported half-life values used in this assessment were calculated using the draft NAFTA degradation kinetics2; Single 

First Order (SFO), Nth-Order Rate Model or Indeterminate Order Rate Equation Model (IORE), and Double First-Order 

in Parallel (DFOP); Representative half-life to be used to calculate model input value for IORE (tR IORE). Values reported 

in the new chemical assessment are shown in italic. At the time of the new chemical assessment half-life values provided 

were based on single first order (SFO) rates that may not have represented the “best” fit or representative kinetic model 

for degradation. Selected representative half-life values are shown in bold. 

2. Reported half-life values are for total extracted sedaxane residues [(SYN524464) or SYN508210 (trans-isomer of 

sedaxane) and SYN508211 (cis-isomer of sedaxane) combined]. 

3. Value was incorrectly reported in new chemical assessment. 

As mentioned above, a large amount of unextracted residues were observed in the soil studies 

(up to 42% of the applied radioactivity). At least twice as much unextracted radioactivity was 

observed in some of the seed treatment studies. It is unclear if these residues are non-extracted 

residues or bound residues, or in the case of the seed studies, residues sorbed to the seed coat or 

taken up by the roots (only shoots were examined separately from the soil). The extraction 

method employed in these studies was not verified for soil aged sedaxane residues or the 

transformation products. Furthermore, the uses of different extraction systems (different 

solvents) were not explored in the submitted studies. Therefore, it cannot be determined if 

another solvent system may have been better suited for these studies. 

The application rates used in all the submitted aerobic metabolism (seed and soil) studies are 

much higher (>15X) than the maximum proposed seed treatment application rates for barley, 

canola, oat, rye, soybean, triticale, and wheat. For some chemicals, the application rate has been 

shown to alter the degradation rate. For example, high application rates may adversely impact the 

microbial activity within a soil decreasing metabolism and limiting the potential identification of 

transformation products. The microbial activity of the treated soils was also not reported in the 

submitted studies; therefore, it cannot be determined if the soil remained active throughout the 

study. 

Sedaxane is moderately mobile (mean KF of and mean 7.3 L/kg-soil; 1/n ranged from 0.81-0.92; 

mean KFOC of 481 L/kgOC; n=6). The leaching potential of sedaxane through soil is correlated 

with the organic carbon fraction of the soil. Based on the KOW (log KOW = 3.3) for sedaxane, it is 

not expected to bioaccumulate in aquatic and terrestrial organisms. A fish bioconcentration study 

confirms that accumulation does not occur. Sedaxane is nonvolatile and volatilization is not 

expected to be a route of dissipation for sedaxane in the environment.
10

Under conditions conductive to degradation (aerobic soil metabolism and photolysis), sedaxane 

has been shown to form five major transformation products, including carbon dioxide. Two of 

the major transformation products, CDCD668094 and CDCD668095, retain both the pyrazole 

and the phenyl ring moieties. Both of these transformation products were observed in aquatic 

photolysis experiments conducted with natural water. Two other products, CSCD465008 and 

CSAA798670, are pyrazole ring amide cleavage products with and without the N-methyl group, 

respectively. Both of these transformation products were observed under aerobic soil conditions, 

while only CSAA798670 was observed in photodegradation studies. Several other minor 

degradation products were observed in the degradation studies including: CSCC210616, 

CSCD728931 and CSCD667584. A number of other minor transformation products were not 

identified in the submitted studies. 

C. Ecological Effects Summary 

Based on the available data, sedaxane is highly toxic to freshwater fish; moderately toxic to 

estuarine/marine fish and freshwater and estuarine/marine invertebrates; and practically nontoxic to birds, mammals, and terrestrial invertebrates (contact) on an acute exposure basis (Table 

3). Chronic exposure resulted in reduced post-hatch survival (100%) in freshwater fish (fathead 

minnows). Chronic exposure in freshwater invertebrates resulted in reduced offspring 

production (NOAEC = 0.75 mg a.i./L). Chronic toxicity data are not available for 

estuarine/marine fish or estuarine/marine invertebrates. Chronic exposure in birds resulted in no 

effects at the highest concentration tested, i.e., 1,050 mg a.i./kg-diet. Chronic exposure resulted 

in reduced body weights, reduced weight gain, and food consumption in mammals (NOAEL = 

41 mg a.i./kg-bw). 

For terrestrial plants, the EC25 values were greater than the highest application rate of 0.0956 lb 

a.i./acre in the seedling emergence study for both monocots and dicots. The most sensitive 

aquatic plant tested was the green algae P. subcapitata with an EC50 value of 1.6 mg a.i./L based 

on reduced biomass and mean cell density. 

Toxicity data for the degradate CSCD465008 were available for freshwater fish, aquatic 

invertebrates and freshwater algae as well as for mammals. Based on the data for the freshwater 

organisms, CSCD465008 appears to be less toxic than the parent as it is practically non-toxic to 

fish and invertebrates with LC50 and EC50 values of >97 and >91.8 mg a.i./L, respectively. The 

degradate’s EC50 value for green algae was >92.5 mg a.i./L. The acute oral study for mammals 

(rat) resulted in a non-definitive value (LD50>2000 mg/kg bw) for the degradate. As the limit 

concentration for the degradate was lower than the LD50 value for parent (i.e., 5000 mg/kg-bw), 

it is not possible to do a comparison of toxicity. As such, this assessment will focus on parent 

sedaxane. 

 
11

Table 3. Summary of Specific Measurement Endpoints for Animals and Plants Considered 

in this Assessment 

TAXA MEASURE OF EFFECT 

Survival, growth and/ 

or reproduction of: 

Species Toxicity Endpoint 

Freshwater Fish 

Acute 

Cyprinus carpio 

Carp 96-hr LC50 = 0.62 mg a.i./L 

NOAEC = 0.37 mg a.i./L; 

LOAEC = 0.73 mg a.i./L 

based on mortality and 

sub-lethal effects including 

surfacing, lethargy, loss of 

equilibrium, and lying on 

the bottom. 

Chronic 

Cyprinus carpio 

Carp NOAEC = 0.11 mg a.i./L1

Based on an acute-tochronic ratio (ACR=5.5) 

using fathead minnow 

acute and chronic 

endpoints and acute carp 

endpoint; LOAEC in the 

chronic fathead minnow 

study was based on 

reduction in post-hatch 

survival at the 469 μg 

a.i./L test concentration 

(100% mortality for this 

treatment group) 

Freshwater 

Invertebrates

Acute 

Daphnia magna

Water flea 48-hr EC50 = 5.96 mg a.i./L 

NOAEC = 1.6 mg a.i./L 

(based on immobility); no 

other sublethal effects 

noted 

Chronic 

Daphnia magna 

Water flea 

21-d NOAEC = 0.75 mg 

a.i./L 

LOAEC (2.4 mg a.i./L) 

based on reduced offspring 

production (no offspring 

produced at this 

concentration). 

Estuarine/Marine 

Fish

Acute 

Cyprinodon variegates 

Sheepshead minnow 96-hr LC50 = 4.2 mg a.i./L 

NOAEC = 0.67 mg a.i./L 

(based on lethargy, loss of 

equilibrium, and lying on 

the bottom). 

Chronic 

Cyprinodon variegates 

Sheepshead minnow NOAEC = 0.76 mg a.i./L2 

Estuarine/Marine chronic 

fish study not available; 

NOAEC based on an 

acute-to-chronic ratio 

(ACR=5.5) using fathead 

minnow acute and chronic 

endpoints and acute 

sheepshead endpoint 

Estuarine/Marine Acute 
12

TAXA MEASURE OF EFFECT 

Survival, growth and/ 

or reproduction of: 

Species Toxicity Endpoint 

Invertebrates Americamysis bahia 

Mysid shrimp 96-hr LC50 = 1.5 mg a.i./L 

NOAEC = 1.2 mg a.i./L 

(based on surfacing and 

erratic swimming). 

Crassostrea virginica 

Eastern oyster 96-hr EC50 = 3.5 mg a.i./L 

NOAEC = 1.3 mg a.i./L 

(based on inhibition of 

shell growth). 

Chronic 

Americamysis bahia 

Mysid shrimp NOAEC = 0.19 mg a.i./L3 

Estuarine/Marine chronic 

invert study not available; 

NOAEC based on an 

acute-to-chronic ratio 

(ACR=7.9) using Daphnia

acute and chronic 

endpoints and acute mysid 

endpoint 

Aquatic Plants Vascular Plants 

Lemna gibba 

Duckweed 

7-d EC50 = 2.7 mg a.i./L Based on reduced dry 

weight. 

NOAEC = 1.2 mg a.i./L Based on reduced dry 

weight. 

Non-vascular Plants 

Pseudokirchneriella 

subcapitata

Algae 

96-hr EC50 = 1.6 mg a.i./L Based on reduced biomass 

and mean cell density 

96-hr NOAEC = 0.99 mg 

a.i./L 

Based on reduced biomass, 

growth rate, yield, and cell 

density 

Birds 

Acute 

Colinus virginianus 

Northern bobwhite quail 

14-d LD50 >2,250 mg 

a.i./kg-bw 

No effects were noted in 

the study; NOAEL = 

2,250 mg a.i./kg-bw 

Serinus canaria

Canary

14-d LD50 >2,000 mg 

a.i./kg-bw 

 NOAEL < 2,000 mg 

a.i./kg-bw based on 

reduced female body 

weight and sublethal 

effects including loss of 

coordination and lethargy 

Sub-acute 

Colinus virginianus 

Northern bobwhite quail

5-d LC50 >5,870 mg a.i./kgdiet 

NOAEC = 3,370 mg 

a.i./kg-diet based on 

reduced body weight gain 

(LOAEC = 5,870 mg 

a.i./kg-diet) (no mortality) 

Chronic 

Anas platyrhynchos

Mallard duck 

22-wk NOAEC = 1,050 mg 

a.i./kg-diet 

No effects were noted in 

the study 

Mammals 

Acute 

Rattus Norvegicus

Rat LD50 = 5,000 mg a.i./kg-bw No effects were noted in 

the study 

Chronic 
13

TAXA MEASURE OF EFFECT 

Survival, growth and/ 

or reproduction of: 

Species Toxicity Endpoint 

Rattus Norvegicus

Rat 

2-gen NOAEL = 41 mg/kgbw (males) 

LOAEL (120 mg/kg-bw) 

based on decreased body 

weights, body weight 

gains, and food 

consumption 

Terrestrial 

Invertebrates 

Acute Contact 

Apis mellifera

Honey Bee 

48-hr LD50 > 98.2 μg 

a.i./bee 

There was 17.5% 

mortality at the limit dose 

Acute Oral

Apis mellifera

Honey Bee 

48-hr LD50 > 4.22 μg 

a.i./bee 

There was 12.5% 

mortality at the limit dose. 

Sub-acute 

Eisenia fetida 

Earthworm 

LC50 > 1,000 mg a.i./kg dw 

soil 

Increased % weight loss 

at two highest 

concentrations (NOAEC 

= 250 mg a.i./kg dw soil); 

no mortality. 

Terrestrial Plants 

Seedling Emergence

Monocots and dicots 

21-d EC25 >0.0956 lbs 

a.i./acre 

None 

21-d NOAEC = 0.0956 lbs 

a.i./acre 

For corn and tomato there 

was 13 and 10% 

inhibition in dry weight, 

respectively, and 6 and 

8% inhibition in mean 

shoot height, respectively. 1 This value is based on an acute-to-chronic ratio (ACR) using acute data from the carp and acute and chronic data from fathead 

minnow [acute carp LC50 = 0.62 mg a.i./L; acute fathead minnow LC50 = 0.91 mg a.i./L; chronic fathead minnow NOAEC = 

0.165 mg a.i./L; fathead minnow ACR = 5.5 (i.e., 0.91/0.165 = 5.5); carp NOAEC = 0.11 (0.62/x = 5.5)]. 2

 This value is based on an acute-to-chronic ratio (ACR) using acute data from the sheepshead and acute and chronic data from 

fathead minnow [acute sheepshead minnow LC50 = 4.2 mg a.i./L; acute fathead minnow LC50 = 0.91 mg a.i./L; chronic fathead 

minnow NOAEC = 0.165 mg a.i./L; fathead minnow ACR = 5.5 (i.e., 0.91/0.165 = 5.5); sheepshead NOAEC = 0.76 (4.2/x = 

5.5)]. 

3

 This value is based on an acute-to-chronic ratio (ACR) using acute data from the mysid and acute and chronic data from 

daphnia [acute mysid LC50 = 1.5 mg a.i./L; acute daphnia LC50 = 5.96 mg a.i./L; chronic Daphnia NOAEC = 0.75 mg a.i./L; 

Daphnia ACR = 7.9 (i.e., 5.96/0.75 = 7.9); mysid NOAEC = 0.19 (1.5/x = 7.9)]. 

 D. Exposure Characterization 

Aquatic Exposure from Sedaxane Use 

Tier 1 surface water modeling for the proposed sedaxane use rates on corn, dried shelled pea and 

beans, rapeseed and sorghum, and potato, were conducted using environmental fate data shown 

in Table 4. Surface water modeling was conducted using GENEEC (version 2). The application 

rate, number, and interval for sedaxane use on dried shelled pea and beans, rapeseed and 

sorghum are shown in Table 5. Output files for GENEEC model simulations are shown in 

Appendix A. 
14

Table 4. Input Parameters Used in GENEEC Modeling to Estimate Sedaxane 

Concentrations Resulting From the Proposed Uses on Corn, Dried Shelled Pea and Beans, 

Rapeseed and Sorghum, and Potato

Input Parameter (Symbol; Unit) Value for Sedaxane Reference 

Molecular Weight 331.37 g/mol Calculated 

using ChemDraw 

Henry’s constant (25 oC) 3.95 x 10-11 atm-m3/mol MRID 47473326 

Calculated 

Vapor Pressure 

25C 1.7 x 10-7 Pa 

1.3x10-9 torr 

20C 6.5 x 10-8 Pa 

4.9x10-10 torr 

47473326 

Solubility in Water (mg/L at 20 oC) 14 47473326 

Hydrolysis Half-life (t1/2 at pH 7) 0, stable 47473318 

Aquatic Photolysis Half-life (days; t1/2

at pH 7) 461 47473319 

Aerobic Soil Metabolism [upper 90th

percentile confidence bound on the 

mean half-life value (t1/2; days)] 

410 47473448 

Aerobic Aquatic Metabolism Half-life 

[water column; upper 90th percentile 

confidence bound on the mean halflife value (t1/2; days)] 

994 47473468 

Anaerobic Aquatic Metabolism Halflife [benthic; upper 90th percentile 

confidence bound on the mean halflife value (t1/2; days)] 

7522 47473468 

Average Soil Partition Coefficient 

(Koc; mL/g) Kfoc = 481 mL/g 47473461 

Gray shading indicates data that are not considered in GENEEC; however, the parameters are 

provided for completeness for possible Tier II modeling is required in the future. 

1. Dark control-adjusted (rate of irradiated – rate of non-irradiated) as well as adjusted to a 12-hour/day 

photoperiod at 40 °N latitude. The artificial light source used in this experiment was determined to be 

equivalent to 0.9 days at 40 °N latitude. 

Table 5: Application Information for Sedaxane Use on Corn, Dried Shelled Pea and Beans, 

Rapeseed and Sorghum, and Potato 

Use 

Number of 

Applications/ 

Application Rate 

(lb a.i./A) 

Interval 

Between 

Applications 

(days) 

corna 2/0.013 30 or 138 

sorghum 2/0.0046 30 

dried shelled pea and 

bean 2/0.002 30 
15

Use 

Number of 

Applications/ 

Application Rate 

(lb a.i./A) 

Interval 

Between 

Applications 

(days) 

rapeseed 2/0.0003 30 

Potatoa 1/0.1 138 

corn-wheat rotationb 1/0.013 and 1/0.008 138 

a. Since the highest single application is for corn and it can be 

reapplied after crop failure it is the only scenario modeled, 

except for potato which was also modeled. 

b. Wheat is another registered crop for sexadane and may be 

rotated with corn 

Surface Water Modeling for Corn, Dried Shelled Pea and Beans, Rapeseed, and Sorghum Seeds 

and Potato Pieces

From the proposed sedaxane use on corn, dried shelled pea and beans, rapeseed and sorghum 

seeds and potato pieces, use on corn and potato are expected to result in the highest EECs. The 

estimated environmental concentrations (EECs) from use on corn are not expected to exceed 

0.78 μg/L for the daily peak, 0.77 μg/L for the 21 day average, and 0.71 μg/L for the 60 day 

average. For potato, the EECs are 3.09 μg/L for the daily peak, 3.02 μg/L for the 21 day 

average, and 2.90 μg/L for the 60 day average. Sedaxane EECs from corn and potato use are 

shown in Table 6. Model inputs and outputs are presented in Appendix A. 

Table 6. Tier I GENEEC Estimated Environmental Concentrations of Sedaxane in Surface Water 

for Seed Treatment on Corn Seeds (the highest estimated EEC) 

Crop 

Estimated Environmental Concentration 

Peak 21-Day Average 60-Day Average 

μg/L 

Corn 0.78 0.77 0.71 

Potato 3.09 3.02 2.90 

Monitoring Data

No monitoring data is available at this time as sedaxane was only recently registered in the 

United States. 

 
16

Terrestrial Exposure from Sedaxane Use on Corn, Dried Shelled Pea and Beans, Rapeseed 

and Sorghum seeds 

Exposure to terrestrial animals was estimated using T-REX version 1.4.1 (potato) and 1.5.1(corn) 

(Table 7). The following tables provide the terrestrial EECs used in this assessment. For seed 

treatments, T-REX only models a single seed planting per year, therefore, if an additional 

planting per year occurred as allowed by the label, this would underestimate the potential 

exposure to non-target organisms on a yearly basis, except for potatoes. Based on the proposed 

label, application to potato pieces is to occur only every other year. As use on corn and potato 

are anticipated to provide the highest EECs, only these uses were modeled. T-REX v.1.5.1 does 

not allow for custom seeding rates (lb seed/A), but rather uses default values (default for potato 

is 5271 lb seed/A; custom seeding rate in this assessment 3333 lb seed/A), therefore, this version 

could not be used to model potatoes. Therefore, T-REX v1.4.1 was used to model potatoes, 

however, this version only calculates RQ values for small birds and mammals. However, the RQ 

values for small birds and mammals are conservative for the other class sizes. Model inputs and 

outputs are presented in Appendix B. 

Table 7. Terrestrial Avian and Mammalian Estimated Environmental Concentrations for Sedaxane from 

Use on Corn Seeds 

Animal 

Size Crop 

Maximum 

Application 

Rate 

Maximum 

Seed 

Application 

Rate 

Avian Nagy 

Dose 

Mammalian 

Nagy Dose 

Available 

AI 

 (lbs ai/A) 

(mg ai/kg 

seed) 

(mg ai/kgbw/day) (mg ai/kgbw/day) (mg ai ft-2) 

Small 

corn, all or 

unspecified 0.0131 359.23 

90.92 76.11 

0.131 Medium 51.84 52.60 

Large 23.21 12.2 

Small 

potato 0.1 30.00 

7.59 6.36 

Medium 1.04 --2 -- 

Large -- -- 1 Due to rounding and assumptions in product density, T-REX v1.5.1 calculates this rate as 0.012 lb a.i./A which 

slightly influences the max. seed app. rate and Nagy doses. However, this slight difference is not expected to 

significantly influence RQs or risk conclusions in this assessment. 2

 T-REX v1.4.1 only calculates EECs for small birds and mammals, however, this will represent a conservative 

estimate for the other animal size classes. 

EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 

1.2.2, 12/26/2006). TerrPlant estimates potential exposure from a single application using 

default assumptions for runoff and spray drift (Table 8). While the potential for dust from 

abraded seeds during planting may occur, the amount of dust is not known and since it is a seed 

treatment conventional routes of spray drift are not expected, so only the runoff values will be 

used in this assessment. EECs are based upon solubility, application rate and minimum 

incorporation depth. A complete description of the input parameters and output is in Appendix 

C. 
17

Table 8. EECs on Plants from Run-off Following Label-Specified Applications of Sedaxane 

Using the TerrPlant Model (lbs a.i./A) 

Crop 

Application 

Rate (lb 

a.i./acre) 

EEC – Runoff to 

Dry Areas (lb 

a.i./acre) 

EEC – Runoff to 

Semi-aquatic 

Areas (lb 

a.i./acre) 

Corn 0.013 0.00013 0.0013 

Potato 0.1 0.001 0.01 

E. Risk Assessment Summary 

Aquatic Species 

 1. Fish 

Table 9 indicates that neither the acute nor chronic LOCs are exceeded for either freshwater fish 

or aquatic-phase amphibians or estuarine/marine fish with the highest estimated peak and 60-day 

average EEC values. 

Table 9. Summarized Acute and Chronic Fish Risk Quotients for Sedaxane Use on Corn and 

Potato Seeds 

Scenario 

Freshwater 

Fish/Aquatic-Phase 

Amphibians (Acute)1,2,4 

Freshwater Fish 

(Chronic)1,2,4 

Estuarine/Marine 

Fish (Acute)1,3,4

Estuarine/ Marine Fish 

(Chronic)1,3,4 

Corn <0.01 <0.01 <0.01 <0.01 

Potato <0.01 0.03 <0.01 <0.01 

1

 Corn: peak EEC 0.78 μg a.i./L, 60-day average EEC 0.71 μg a.i./L. Potato: peak EEC 3.09 μg a.i./L, 60-day 

average EEC 2.90 μg a.i./L 

2

 Acute and chronic toxicity endpoints were 620 μg a.i./L (LC50) and 110 μg a.i./L (NOAEC), respectively, for 

freshwater fish. 

3

 Acute and chronic toxicity endpoints4200 were μg a.i./L (LC50) and 760 (NOAEC), respectively, for 

estuarine/marine fish. 

4

 Risk Quotients are calculated using the following formulas: EEC/LC50 for acute exposure and EEC/NOAEC 

for chronic exposure 

5

Acute LOC for freshwater fish = 0.05 for endangered species, 0.1 for restricted use, and 0.5 for non-listed 

species

 2. Aquatic Invertebrates 

Table 10 indicates that neither the acute nor chronic levels of concern (LOC) are exceeded for 

freshwater invertebrates. For estuarine/marine invertebrates, the acute and chronic LOC is not 

exceeded. 
18

Summarized Acute and Chronic Aquatic Invertebrate Risk Quotients for Sedaxane Use on Corn and 

Potato Seeds 

Table 10. Summarized Acute and Chronic Aquatic Invertebrate Risk Quotients for Sedaxane Use on 

Corn and Potato Seeds

Scenario Freshwater 

Inv. (Acute)1,2.4 

Freshwater Inv. 

(Chronic)1,2,4

Estuarine/Marine 

Inv. (Acute)1,3,4 

Estuarine/Marine 

Inv. (Chronic)1,3,4

Corn <0.01 <0.01 <0.01 <0.01 

Potato <0.01 <0.01 <0.01 <0.01 

1

 Corn: peak EEC 0.78 μg a.i./L, 21-day average EEC 0.77 μg a.i./L. Potato: peak EEC 3.09 μg a.i./L, 21-

day average EEC 3.02 μg a.i./L 

2

 Acute and chronic toxicity endpoints were 5960 μg a.i./L (LC50) and 750 μg a.i./L (NOAEC), respectively, 

for freshwater invertebrates. 

3

 Acute and chronic toxicity endpoints were 1500 μg a.i./L (LC50) and 190 μg a.i./L (NOAEC), respectively, 

for estuarine/marine invertebrates. 

4

 Risk Quotients are calculated using the following formulas: EEC/LC50 for acute exposure and EEC/NOAEC 

for chronic exposure 

5

Acute LOC for freshwater and marine/estuarine invertebrates = 0.05 for endangered species, 0.1 for restricted 

use, and 0.5 for non-listed species 

 3. Aquatic Plants 

Table 11 indicates that the LOCs for aquatic non-vascular and vascular plants are not exceeded 

for the proposed uses. 

Table 11Aquatic Plant Risk Quotients for Sedaxane Use on Corn and Potato Seeds 

Scenario Non-vascular Plants 

(Non-listed) 

Non-vascular 

Plants (Listed) 

Vascular Plants 

(Non-listed) 

Vascular Plants 

(Listed) 

Corn RQ < 0.01 RQ <0.01 RQ < 0.01 RQ < 0.01 

Potato RQ < 0.01 RQ < 0.01 RQ < 0.01 RQ < 0.01 

1 Corn peak EEC 0.78 μg a.i./L. Potato: peak EEC 3.09 μg a.i./L 

2

 Endpoints are 1600 μg a.i./L (EC50) and 990 μg a.i./L (NOAEC) for non-vascular plants and 2700 μg 

a.i./L (EC50) and 1200 μg a.i./L (NOAEC) for vascular plants . 3

 Risk Quotients are calculated using the following formula: EEC/EC50 4 LOC for aquatic plants = 1 

Terrestrial Species 

4. Birds, Reptiles and Terrestrial-Phase Amphibians 

There are no toxicity studies available for reptiles or terrestrial-phase amphibians. Therefore, 

birds are used as a surrogate. There were no mortalities in any of the available acute and 
19

subacute avian studies. No RQs were calculated; however, EECs were compared to the highest 

test dose to estimate how closely they approach or overlap the LOC. The highest 

dose/concentrations tested in the acute/subacute avian studies were 2,250 mg a.i./kg bodyweight 

and 5,870 mg a.i./kg diet, respectively, both with bobwhite quail. Using comparisons between 

the terrestrial EECs estimated from T-REX v. 1.4.1 or 1.5.1 (Appendix B) and the highest dose 

tested (adjusted for bodyweight of surrogate animal size (20, 100, and 1000 g) in the acute oral 

study, the results show that for all of the application rates, for the proposed uses, all of the EEC 

values are lower than one-half the highest dose tested, which correlates to an LOC of 0.5 for 

non-listed birds. In evaluating risk to listed birds, the EECs are not greater than 1/10th of the 

highest dose tested in the studies, which correlated to the acute listed LOC of 0.1, for small birds 

consuming corn seeds treated with sedaxane. In the acute oral study with canaries, there were 

sublethal effects observed at the limit dose of 2,000 mg a.i./kg-bw including reduced body 

weight, and loss of coordination and lethargy. When comparing this limit dose to the EECs, the 

EECs are approximately 20 times lower than the limit dose. Therefore, while there is 

uncertainty, the likelihood of adverse effects from acute exposure is anticipated to be low. 

Following chronic exposure, the chronic LOC for birds (LOC = 1) is not exceeded for birds 

(Table 12). Therefore, acute and chronic risk to birds (surrogates for terrestrial-phase 

amphibians and reptiles) is anticipated to be low. 

Table 12. RQs for Avian and Mammalian Species from Dietary Exposure to Sedaxane from Seed Treatments 

to Corn and Potato 

Crop 

Risk Quotients† 

Avian (20 g) Mammalian (15 g) 

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic 

corn, all or 

unspecified NA1 NA1 0.34 0.01 <0.01 0.84 

 Avian (100 g) Mammalian (35 g) 

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic 

corn, all or 

unspecified NA1 NA1 0.34 0.01 <0.01 0.72 

 Avian (1000 g) Mammalian (1000 g) 

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic 

corn, all or 

unspecified NA1 NA1 0.34 <0.01 <0.01 0.39 

 Avian (20 g) Mammalian (15 g) 

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic 

Potato2 NA1 NA1 0.03 <0.01 0.01 0.073 

1

 RQs not calculated due to non-definitive endpoint (LD50 greater than highest concentration tested) 

2

 RQs not calculated for medium and large avian and mammalian class sizes due to model limitations in T-REX 

versions. However, RQs for small birds and mammals is conservative for other class sizes, and RQs for small 

animals do not exceed the LOC. 

3

 T-REX v1.4.1 calculates the chronic mammalian RQ using the chronic dietary NOAEC whereas T-REX v1.5.1 

adjusts for body weight using the NOAEL, therefore this RQ was recalculated to account for body weight 

 

Acute RQ #1 = (mg ai /kg-bw/day) / LD50 

Acute RQ #2 = mg ai ft-2 /(LD50*bw) 
20

Avian Chronic RQ = mg kg-1 seed / NOAEL Mammalian Chronic RQ = mg a.i./kg-bw/day / adjusted NOAEL 

5. Mammals 

Acute and chronic RQs did not exceed the LOC for mammals (Table 12). 

6. Terrestrial invertebrates 

The acute contact LD50 for honey bees is >98.2 μg a.i./bee; there was 17.5% mortality observed 

at this limit dose. Based on the acute contact toxicity study to honeybees, sedaxane is classified 

as practically non-toxic to honeybees. Toxicity information for beneficial insects in screeninglevel risk assessments is used to develop precautionary label language where necessary. Based 

on the available data, precautionary label language for bees is not necessary. However, the 

potential effects to larvae/pupae life stages of honeybees are unknown as the available data tested 

adult honeybees. 

7. Terrestrial Plants

Terrestrial plants adjacent to the treatment area are considered in this assessment. 

The LOCs for risk to listed and non-listed terrestrial plants were not exceeded for monocots or 

dicots (Table 13). However, there is some uncertainty regarding the results for listed species. 

For corn and tomato there was 13 and 10% inhibition in dry weight, respectively, and 6 and 8% 

inhibition in mean shoot height, respectively, in the available seedling emergence study at the 

limit concentration. For dry weight, the minimum significant difference that can be detected in 

the study, based on a power analysis, is approximately 20% for corn and 44% for tomato. 

Therefore, there is uncertainty regarding whether or not the true NOAEC is the limit 

concentration. The NOAEC or EC05 is used to evaluate effects to listed terrestrial plants. 

Currently, the proposed single application rate for seed treatment for corn and potato is 

approximately 74X and 9.6X lower than the application rate used in the study. Therefore, 

additional testing for corn and tomato is not needed at this time. However, if additional 

uses/rates are proposed, this will be re-evaluated and it may be recommended that a Tier II 

seedling emergence study be conducted to better understand the potential effects to listed 

terrestrial plants. 

Table 13. RQ values for plants in dry and semi-aquatic areas exposed to sedaxane from corn and potato seed 

use through runoff 

Plant Type Listed Status Dry Semi-Aquatic 

Monocot listed <0.1 0.10 

Dicot listed <0.1 0.10 

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group. 
21

8. Uncertainties 

Exposure to dust from abraded seeds during planting may be a possibility. If the assumption is 

that all of the sedaxane applied to the seeds is abraded and released as dust, then the maximum 

concentration that may be then deposited on dietary items is 0.013 lb a.i./A (calculated from the 

maximum seeding rate for corn). This application rate was used as the application rate for foliar 

application in T-REX and the EECs were compared to the limit concentration. For terrestrial 

invertebrates, the resulting arthropod EEC was 1.9 mg/kg and the limit concentration was 767 μg 

a.i./g (converted to μg a.i./g based on the weight of one bee (0.128 g)), therefore the EEC is 420 

times lower than the limit dose. For birds and mammals consuming dietary items exposed to the 

dust, the application rate of 0.013 lb a.i./A was used as a foliar application, and all the resulting 

RQs were less than the LOC. For terrestrial plants, the application rate of 0.013 lb a.i./A is 

approximately at least 10X lower than the limit concentration used in the terrestrial plants 

toxicity testing. For aquatic organisms, the assumption was that all of the available sedaxane 

was available for entry into the aquatic environment therefore, the application rate of 0.013 lb 

a.i./A was used in deriving the RQs and no LOC exceedances were observed. Therefore, the 

likelihood for adverse effect from exposure to dust is anticipated to be low. 

In the new chemical screening risk assessment for sedaxane (D386380), other effects 

uncertainties such as avian chronic and aquatic plant toxicity data as well as the observation of 

degradation products and their potential toxicity were discussed. However, those uncertainties 

are not anticipated to affect the risk conclusions in this assessment, except for possibly the 

chronic avian evaluation. The chronic reproduction study with Northern bobwhite quail (Colinus 

virginianus) was classified as unacceptable (MRID 47473475) because control mortality was 

13% in the parental group, which is greater than the allowable 10%. Two females in the control 

died during the study with one found with head caught in caging; however, due to their deaths, 

their penmates were sacrificed which resulted in less than 90% overall survival at test 

termination (87%). Based on the study results the reported NOAEC for the bobwhite quail (337 

mg a.i./kg-diet) was lower than the mallard duck NOAEC used in this assessment (1050 mg 

a.i./kg-diet). As such, it appears that the bobwhite quail may be the more sensitive of the two 

tested species. If this NOAEC is used in the RQ calculation for corn, then the RQ (1.19) would 

be slightly greater than the chronic LOC of 1. The RQs for the other uses are less than the LOC. 

For corn, a reduction of 17% in the exposure rate would result in an RQ less than the LOC. In 

modeling exposure via treated seeds, the assumption is that there are enough seeds available for 

consumption to reach the LOC. Based on the information, it appears that the planting depth of 

corn is 2 inches, which may limit access to some seeds which should require the birds to glean a 

greater area to acquire enough seeds to reach the LOC. Based on the proposed label for corn, 

there is 0.1 mg a.i./seed and using a seeding rate of 33 lb seed/A that is 59,400 seeds/A which 

appears to be a high end estimate based on the BEAD memo. Using the application rate, the 

EEC is 400 mg a.i./kg seed which means that it would take 4,000 seeds to reach this EEC. A 

bird would need to glean every available seed in 2,900 sq. feet to consume enough a.i. to reach 

the EEC. As the seeds are anticipated to be buried, not all seeds should be available for 

gleaning. Additionally, the ability of the bird to consume 4,000 seeds in duration necessary to 

elicit a response may not be feasible. It is recognized that the energy requirements for birds in 

the lab are probably not the same as in the field and the birds in the lab are fed a high nutrient 
22

diet, therefore the toxic response in a bird in the field may be different than one in the lab. 

However, it seems that based on the necessary area and potentially available seeds, that the birds 

may not consume enough a.i. to reach the EEC. Therefore, an additional chronic study with 

bobwhite quail is not requested at this time. 

 
23

Appendix A 

GENEEC output 

 
24

APPENDIX B 

T-REX v. 1.5.1 

Corn 

 

Chemical:

Name of seed treatment formulation:

Percent AI in formulation: 46% 0 8.33

Tested Body

Weight (g)

Avian LD50: 2000.00 26 1922.82 Small (20g)

Avian repro. NOAEC: 1050.00 2447.85 Medium (100g)

3457.67 Large (1000g)

Mammalian LD50: 5000.00 350 10989.15 Small (15g)

Mammalian NOAEL: 820.00 8891.40 Medium (35g)

3845.80 Large (1000g)

Small (15g) 90.11

Medium (35g) 72.91

Large (1000g) 31.54

Crop

Maximum 

Application 

Rate

Maximum Seed 

Application Rate Avian Nagy Dose

Mammalian Nagy 

Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg-bw/day) (mg ai/kg-bw/day) (mg ai ft-2)

Small 90.92 76.11

Medium 51.84 52.60

Large 23.21 12.20

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.05 0.003 0.34 0.01 0.00 0.84

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.02 0.001 0.34 0.01 0.00 0.72

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified 0.01 0.00 0.34 0.00 0.00 0.39

† Acute RQ #1 = (mg ai /kg-bw/day) / LD50

Acute RQ #2 = mg ai ft-2 /(LD50*bw)

Avian Chronic RQ = mg kg-1 seed / NOAEL

Mammalian Chronic RQ = mg a.i./kg-bw/day / adjusted NOAEL

Avian (1000 g) Mammalian (1000 g)

Animal Size

corn, all or unspecified 0.012 359.23 0.12

Crop

sedaxane

vibrance

Density of product (lbs/gal):

Data inputs are in blue

Avian (100 g) Mammalian (35 g)

Avian (20 g) Mammalian (15 g)

Risk Quotients†

Endpoints Adjusted LD50 Size class for 

adjusted LD50 Reported

Adjusted NOAEL for Mammals
25

Potato (potato not listed as a crop in T-REX 1.4.1, so inputs entered into barley row) 

 

Chemical:

Name of seed treatment formulation:

Percent AI in formulation: 46% 0 8.33

Tested Body

Weight (g)

Avian LD50: 2000.00 26 1922.82

Avian repro. NOAEC: 1050.00

Mammalian LD50: 5000.00 350 10989.15

Mammalian NOAEC: 820.00

Crop

Maximum 

Seeding Rate 

(lbs/acre)

Application 

Rate

Application 

Rate

(fl oz/cwt) (lbs. Ai/cwt)

Barley 3333 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0.08 0.0030

beans 160 http://www.ext.nodak.edu/extpubs/plantsci/rowcrops/a1133-1.htm#Planting 0 0.0000

dried beans 160 http://www.ext.nodak.edu/extpubs/plantsci/rowcrops/a1133-1.htm#Planting 0 0.0000

lima beans (succulent) 100 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

snap beans 100 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Canola 5 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Corn 25 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Cotton 18 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Oats 87 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Onion 15 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

cowpeas/ blackeyed peas 50 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Pea 180 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

lupine 170 http://www.hort.purdue.edu/newcrop/afcm/lupine.html 0 0.0000

grain lupine 170 http://www.hort.purdue.edu/newcrop/afcm/lupine.html 0 0.0000

field peas 225 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Peanuts 135 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Rice 160 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Rye 109 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0

Safflower 100 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Sorghum 8 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Soybeans 167 http://www.nsrl.uiuc.edu/aboutsoy/production02.html 0 0.0000

soybeans, edible 100 http://www.nsrl.uiuc.edu/aboutsoy/production02.html 0 0.0000

Sugar beets 8 http://www.agecon.ucdavis.edu/outreach/crop/Archives/SugarBeets.pdf 0 0.0000

Triticale 109 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0 0.0000

Wheat 156 http://www.ipmcenters.org/cropprofiles/CP_form.cfm 0

Crop

Maximum 

Application Rate

Maximum Seed 

Application 

Rate

Avian Nagy 

Dose

Mammalian 

Nagy Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg-bw/day)(mg ai/kg-bw/day) (mg ai ft-2)

Barley 0.1000 30.00 7.59 6.36 1.04

beans 0.00 0.00 0.00 0.00 0.00

dried beans 0.00 0.00 0.00 0.00 0.00 20 g Bird 5.061777181

lima beans (succulent) 0.00 0.00 0.00 0.00 0.00 15 g Mammal 3.178078065

snap beans 0.00 0.00 0.00 0.00 0.00

Endpoints Reported Adjusted LD50

Nagy allometry

Food ingestion value g/day

sedaxane

Reference

Density of product (lbs/gal):

Data inputs are in blue

Animal

Questions? 

Comments? 

Click here

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

Barley 0.004 0.027 0.03 0.001 0.01 0.04

beans 0.00 0.00 0.00 0.00 0.00 0.00

dried beans 0.00 0.00 0.00 0.00 0.00 0.00

lima beans (succulent) 0.00 0.00 0.00 0.00 0.00 0.00

snap beans 0.00 0.00 0.00 0.00 0.00 0.00

Crop Avian (20 g) Mammalian (15 g)

Risk Quotients†
26

APPENDIX C 

TERRPLANT v. 1.2.2 

 

TerrPlant v. 1.2.2

Green values signify user inputs (Tables 1, 2 and 4). 

Input and output guidance is in popups indicated by red arrows.

Chemical Name

PC code

Use

Application Method

Application Form 

Solubility in Water (ppm)

Input Parameter Symbol Value Units

Application Rate A 0.013 lb a.i./A

Incorporation I 1 none

Runoff Fraction R 0.02 none

Drift Fraction D 0 none

Equation EEC

(A/I)*R 0.00026

(A/I)*R*10 0.0026

A*D 0

((A/I)*R)+(A*D) 0.00026

((A/I)*R*10)+(A*D) 0.0026

Plant type EC25 NOAEC EC25 NOAEC 

Monocot x 0.0956 x x

Dicot x 0.0956 x x

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed #VALUE! #VALUE! #DIV/0!

Monocot listed <0.1 <0.1 <0.1

Dicot non-listed #VALUE! #VALUE! #DIV/0!

Dicot listed <0.1 <0.1 <0.1

Table 3. EECs for sedaxane. Units in lb a.i./A.

Runoff to dry areas

Runoff to semi-aquatic areas

Spray drift

Total for dry areas

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

Seedling Emergence Vegetative Vigor

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to sedaxane through runoff 

and/or spray drift.*

Table 4. Plant survival and growth data used for RQ derivation. Units are in lb a.i./A.

Description

Total for semi-aquatic areas

Table 1. Chemical Identity.

sedaxane

corn seeds

Table 2. Input parameters used to derive EECs.

ground

granule

14

129223
27

TerrPlant v. 1.2.2

Green values signify user inputs (Tables 1, 2 and 4). 

Input and output guidance is in popups indicated by red arrows.

Chemical Name

PC code

Use

Application Method

Application Form 

Solubility in Water (ppm)

Input Parameter Symbol Value Units

Application Rate A 0.1 lb a.i./A

Incorporation I 2 none

Runoff Fraction R 0.02 none

Drift Fraction D 0 none

Equation EEC

(A/I)*R 0.001

(A/I)*R*10 0.01

A*D 0

((A/I)*R)+(A*D) 0.001

((A/I)*R*10)+(A*D) 0.01

Plant type EC25 NOAEC EC25 NOAEC 

Monocot x 0.0956 x x

Dicot x 0.0956 x x

Plant Type Listed Status Dry Semi-Aquatic Spray Drift

Monocot non-listed #VALUE! #VALUE! #DIV/0!

Monocot listed <0.1 0.10 <0.1

Dicot non-listed #VALUE! #VALUE! #DIV/0!

Dicot listed <0.1 0.10 <0.1

Description

Total for semi-aquatic areas

Table 1. Chemical Identity.

sedaxane

potato seeds

Table 2. Input parameters used to derive EECs.

ground

granule

14

129223

Table 3. EECs for sedaxane. Units in lb a.i./A.

Runoff to dry areas

Runoff to semi-aquatic areas

Spray drift

Total for dry areas

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

Seedling Emergence Vegetative Vigor

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to sedaxane through runoff 

and/or spray drift.*

Table 4. Plant survival and growth data used for RQ derivation. Units are in lb a.i./A.