Page 2 

fate and potential ecological effects of orthosulfamuron. 
1 

 

Problem Formulation for the 

Environmental Fate and Ecological Risk, Endangered 

Species, and Drinking Water Assessments 

in Support of the Registration Review of 

Orthosulfamuron 

Orthosulfamuron (CAS 213464-77-8)

Prepared by:

Mary Clock-Rust, Biologist 

Katrina White, Ph.D., Biologist 

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Cheryl Sutton, Ph.D., Environmental Scientist 

Thomas Steeger, PhD., Senior Biologist 

Marietta Echeverria, Branch Chief 

December 1, 2011

O

N

CH3

H C3

N

H

S

N

H

N

H

O

O

O

N

N

O CH3

O CH3
2 

Table of Contents 

I. Purpose ....................................................................................................................................... 5

II. Description of Regulatory Action .............................................................................................. 5

III. Conclusions from Previous Risk Assessments ........................................................................ 5

IV. Mechanism of Action .............................................................................................................. 6

V. Overview of Pesticide Usage .................................................................................................... 7

VI. Environmental Fate and Transport ........................................................................................ 10

A. Monitoring Data ............................................................................................................. 19

B. Clean Water Act .................................................................................................................. 20

VII. Receptors .............................................................................................................................. 20

A. Effects to Aquatic Organisms ............................................................................................. 23

B. Effects to Terrestrial Organisms ......................................................................................... 25

C. Degradate Toxicity .............................................................................................................. 27

D. Ecological Incidents ............................................................................................................ 27

VIII. Evaluation of Non-definitive Toxicity Values ............................................................... 27

IX. Ecosystems Potentially at Risk .............................................................................................. 29

X. Assessment Endpoints ............................................................................................................. 29

XI. Identification of Stressors of Concern ................................................................................... 29

XII. Conceptual Model ................................................................................................................. 36

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

B. Conceptual Diagram ............................................................................................................ 37

XIII. Analysis Plan........................................................................................................................ 41

A. Measures of Exposure .................................................................................................... 42

1. Exposure to Aquatic Organisms in the Rice Paddy ......................................................... 42

2. Exposure to Terrestrial Animals via Residues on Food Items .......................................... 43

3. Exposure to Terrestrial Animals via Drinking Water ....................................................... 43

4. Exposure to Terrestrial Plants from Spray Drift ............................................................... 44

5. Exposure to Terrestrial Plants from Residues in Irrigation Water .................................... 44

6. Exposure to Aquatic Organisms based on Monitoring Data ............................................ 44

7. Exposure to Spray Drift .................................................................................................... 44

B. Measures of Effect ......................................................................................................... 44

C. Integration of Exposure and Effects ............................................................................... 45

1. Deterministic and Probabilistic Assessment Methods ..................................................... 46

D. Endangered Species Assessments .................................................................................. 46

E. Human Health Drinking Water Assessment ........................................................................ 46

F. Endocrine Disruptor Screening Program ........................................................................... 47

XIV. Preliminary Identification of Data Gaps .............................................................................. 48

A. Fate ................................................................................................................................. 48

1. Rationales for Requesting Fate Studies .......................................................................... 50

B. Effects ............................................................................................................................. 53

1. Rationales for Requesting Effects Studies ....................................................................... 55

2. Rationales for Not Requesting Effects Studies ................................................................ 56

3. Degradate Toxicity Data .................................................................................................. 58

4. Testing on Typical end-use products (TEP) .................................................................... 59

XV. Other Information Needs...................................................................................................... 60
3 

XV. References ............................................................................................................................ 61

 

List of Tables

Table 1. Summary of currently registered products of orthosulfamuron. ...................................... 8

Table 2. Summary of physical-chemical properties of orthosulfamuron1 .................................... 11

Table 3. Summary of other environmental fate and transport properties of orthosulfamuron. ... 12

Table 4. Summary of maximum amount of transformation products observed in fate studies. .. 19

Table 5. Most Sensitive Species Evaluated for Potential Ecological Effects from 

Orthosulfamuron. ........................................................................................................... 21

Table 6. Comparison of Measured Toxicity Endpoints for Orthosulfamuron with Estimated 

Aquatic Toxicity Endpoints for DBS Acid, DBS amide, DB amine, and DOP amine 

(estimated using ECOSAR versioin 1).* ....................................................................... 34

Table 7. Summary of residues of concern for different classes of organisms. ............................ 35

Table 8. Summary of Submitted Environmental Fate Studies, Study Classifications and Data 

Gaps for Orthosulfamuron and Its Degradates .............................................................. 48

Table 9. Summary of Submitted Ecological Effects Studies and Data Gaps for Parent 

Orthosulfamuron ............................................................................................................ 53

Table 10. Summary of Submitted Ecological Effects Studies and Data Gaps for 

Orthosulfamuron Degradates ......................................................................................... 58

List of Figures 

Figure 1. Acres Planted in Rice by County for Selected States in the United States. Prepared by 

the National Agricultural Statistics Service (NASS) and downloaded from 

http://www.nass.usda.gov/Charts_and_Maps/Crops_County/ar-pl.asp ......................... 9

Figure 2. Degradation Pathway of Orthosulfamuron (adapted from MRID 46588508, page 40). 

Abbreviations are defined in text above figure. ........................................................... 18

Figure 3. Structures of Orthosulfamuron and O-desmethyl orthosulfamuron ............................. 30

Figure 4. Structures of DOP urea and O-desmethyl DOP urea ................................................... 32

Figure 5. Structures of DBS Acid, DOP Amine, DBS Amide and DB Amine ........................... 34

Figure 6. Conceptual model depicting stressors, exposure pathways, and potential effects to 

aquatic organisms from the use of orthosulfamuron to rice. ........................................ 39

Figure 7. Conceptual model depicting stressors, generic exposure pathways, and potential 

effects to terrestrial organisms (terrestrial plants, terrestrial invertebrates, and dietary 

routes of exposure for terrestrial vertebrates) from the use of orthosulfamuron on rice.

 ...................................................................................................................................... 40

Figure 8. Conceptual model depicting stressors, drinking water and inhalation exposure 

pathways, and potential effects to terrestrial animals from the use of orthosulfamuron 

on rice. .......................................................................................................................... 41

List of Appendices 

Appendix A. Supplemental Environmental Fate Information 

Appendix B. Summary of Relevant Phenyl Urea Toxicity Data and Comparison of Structures to 
4 

DOP Urea and o-desmethyl urea Appendix J. Identification of Transformation 

Products and Listing of the Maximum Amounts Observed in Fate Studies. 

Appendix C. ECOSAR Output 

Appendix D. Ecological Toxicity Summary for Aquatic and Terrestrial Organisms from 

Orthosulfamuron 

Appendix E. Results from Screening Imbibition Program (SIP) and the Screening Tool for 

Inhalation Risk Assessment (STIR) 

Appendix F. Preliminary Estimated Environmental Concentration for the Parent and Degradates 

Using the Tier I Rice Model (version 1, May 8, 2007). 

Appendix G. Example T-Rex Input and Output for Orthosulfamuron. 

Appendix H. Example Terrplant (v. 1.2.2) Input and Output for Orthosulfamuron. 

Appendix I. List of Label Statements Relevant to the Environmental Risk Assessment. 

Appendix J. Identification of Transformation Products and Listing of the Maximum Amounts 

Observed in Fate Studies. 

Appendix K. Calculations for Ground Water Used for Irrigation Exposure 

Appendix L. Preliminary Estimate of Exposure and Risk to Terrestrial Animals for DOP urea 

and O-desmethyl DOP urea.

Appendix M. Data Table for Non-Guideline Studies 
5 

I.  Purpose

The purpose of this problem formulation is to provide an understanding of the environmental fate 

and ecological effects of the registered uses of orthosulfamuron (1-(4,6-Dimethoxypyrimidin-2-

yl)-3-[2-(dimethylcarbamoyl)phenylsulfamoyl]urea). It is a systemic herbicide registered to 

control a variety of annual and perennial broadleaf weeds and sedges in rice production (USEPA, 

2010a). This document will provide a plan for analyzing data relevant to orthosulfamuron and 

for conducting environmental fate and ecological risk, endangered species, and drinking water 

assessments for its registered uses. Additionally, this problem formulation is intended to identify 

data gaps, uncertainties, and potential assumptions used to address those uncertainties, relative to 

characterizing the ecological risk associated with the registered uses of orthosulfamuron. 

II. Description of Regulatory Action

The Food Quality Protection Act of 1996 mandated the Environmental Protection Agency (EPA) 

to implement a new program for assessing the risks of pesticides, i.e., Registration Review 

(http://www.epa.gov/oppsrrd1/registration_review/). All pesticides distributed or sold in the 

United States generally must be registered by EPA. The decision to register a pesticide is based 

on the consideration of scientific data and other factors showing that it will not cause 

unreasonable risks to human health, workers, or the environment when used as directed on 

product labeling. The Registration Review program is intended to ensure that, as the ability to 

assess risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects to human health and the 

environment. Changes in science, public policy, and pesticide use practices will occur over time. 

Through the new Registration Review program, the Agency periodically reevaluates pesticides to 

ensure that as change occurs, products in the marketplace can be used safely. 

As part of the implementation of the new Registration Review program pursuant to Section 3(g) 

of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Agency is beginning its 

evaluation to determine whether orthosulfamuron continues to meet the FIFRA standard for 

registration. This problem formulation for the environmental fate and ecological risk assessment 

chapter in support of the registration review is intended for the initial docket opening the public 

phase of the review process. 

III.  Conclusions from Previous Risk Assessments

The Agency conducted a new chemical ecological risk assessment and drinking water 

assessment on orthosulfamuron in 2006 and the assessments serve as a basis for this problem 

formulation. No other assessments on orthosulfamuron have been completed in EFED. The 

assessments are briefly discussed below. 

Ecological Risk Assessment 

In 2006, EFED completed a New Chemical ecological risk assessment evaluating the potential 

risk posed by use of orthosulfamuron on rice at a maximum application rate of 0.0689 lbs active 
6 

ingredient (a.i.)/acre(A) for water dispersable granule applications and 0.0663 lbs a.i./A for the 

dry granule formulation (USEPA, 2006, D333514). The products could be applied by either 

ground or aerial application once per year. The screening level risk assessment identified the 

potential for direct effects to aquatic vascular plants, dicotyledonous (dicot) terrestrial plants, and 

monocotyledonous (monocot) terrestrial plants. The risk assessment also highlighted the 

potential for indirect effects to all taxa due to direct effects on plants if the taxa rely on plants for 

food or habitat for some portion of their life cycle. 

Drinking Water Assessment 

A drinking water assessment was completed for the same use pattern as evaluated in the 

ecological risk assessment (USEPA, 2006, 330828). Estimated drinking water concentrations 

(EDWCs) in surface water were estimated using the Interim Rice model and ground water 

concentrations were estimated using Sci-Grow (version 2.3). Peak EDWC were 40.5 μg/L in 

surface water and 0.611 μg/L in ground water. The annual mean EDWCs were <40.5 μg/L and 

<0.611 μg/L in surface water and groundwater, respectively. Whether these values will result in 

a risk concern is determined by comparing these values to toxicity endpoints to determine 

whether exposure is likely to exceed levels were effects are observed. Because of the absence of 

data on orthosulfamuron, the effects of drinking water treatment were not considered in the 

assessment. 

IV.  Mechanism of Action

Orthosulfamuron is associated with the following chemical classes: pyrimidinylsulfonylurea 

(Wood, 2009), sulfonylureas (ISAGRO), and sulfamoylurea (USEPA, 2006, D333514). It is a 

systemic post-emergent herbicide registered to control a variety of annual and perennial 

broadleaf weeds and sedges in rice production (USEPA, 2010a). Its mode of action for plants is 

through inhibition of the plant enzyme acetolactate synthase (ALS inhibitor), also known as 

acetohydroxyacid synthase (Ware and Whitacre, 2004). Inhibition of this enzyme blocks 

biosynthesis of the branch chain amino acids valine, leucine, and isoleucine involved in plant 

growth and leads to plant death. It is applied early post-emergence to the weed and is rapidly 

taken up into leaves and roots and translocated to other plant tissues (USEPA, 2010a). The 

selectivity of the herbicide is due to differential rates of metabolism in different plant species 

(USEPA, 2010a). 

The registrant has proposed the following as the mode of action for orthosulfamuron for 

vertebrates, as cited in the Health Effects Division’s 2007 risk assessment (USEPA, 2007, 

D319264): 

“In rats, orthosulfamuron exposure results in increased incidences of thyroid follicular 

cell adenomas. The registrant has proposed a mitogenic mode of action for the 

tumorigenic effects of orthosulfamuron, which involves induction of uridinediphosphateglucuronosyltransferase (UDP-GT), leading to increased elimination of thyroid hormone 

(T4) and subsequent pituitary release of thyroid stimulating hormone (TSH). The 

prolonged release of TSH results in thyroid hypertrophy, hyperplasia, and eventually, 

tumor formation. The [Cancer Assessment Risk Committee] CARC determined that it is 
7 

possible that exposure to orthosulfamuron could cause thyroid tumors via perturbation of 

thyroid-pituitary functioning, due to enhanced hepatic clearance of thyroxin. However, 

the thyroid hormone data, which are critical to delineating a sequence of key events 

leading to tumor formation, are inadequate. Thus, the available data do not fully support 

the proposed MOA.” 

V.  Overview of Pesticide Usage

Orthosulfamuron was first registered in 2004 under a Section 5 Experimental Use Permit (EUP) 

with the first Section 3 registrations becoming active in 2007. The only currently registered use 

is as an herbicide on rice. It may be used to control barnyardgrass, Echinochloa crus-galli, 

propanil-resistant barnyardgrass, other annual grasses, and certain sedge and broadleaf weeds. It 

may be applied to dry soil of dry-seeded rice before, during, or after planting. It may also be 

applied to foliage, for dry- or wet-seeded rice. For wet-seeded rice applications, some labels 

indicate that rice be flushed after a foliar application to maximize root adsorption. Formulations 

include water dispersable granules and dry granules and both formulations may be applied via 

aerial and ground broadcast. All labels prohibit applications via chemigation or irrigation 

systems. There are currently eight registered labels, i.e., four state special local need Section 

24C labels and four Section 3 labels. Table 1 provides details on the currently registered uses of 

orthosulfamuron.1

 The maximum single application rate is 0.067 lbs a.i./A and one application 

per season or year is allowed. 

 

1

 EPA Registration Number 80289-4 is the only technical product with 99.0% orthosulfamuron . This product is 

not included in Table 1. 
8 

Table 1. Summary of currently registered products of orthosulfamuron. 

Reg#/ 

Product 

Name 

Percent 

a.i. Form. 

Max Seasonal 

Application 

Rate 

(lbs a.i./A) 

Application 

Method Type 

Ground/ 

Aircraft 

Application 

Method Timing 

Geographic 

Limitations 

S

Lim

80289-13/ 

STRADA 

XT 

50.0a WG 0.066 

Broadcast to 

Soil or Foliage / 

wet and dry 

seeded rice 

Ground/ 

Aircraft 

Delayed 

preemergence/ 

Postemergence/ 

Preplant/ 

Preemergence 

Can be used 

in AR, LA, 

MS, MO, TN, 

and TX 

Do not 

or loam

Max w

10 mph 

app an

ae

80289-6/ 

STRADA® 

GR 

0.50 G 0.067 Broadcast/ Wet seeded rice Aircraft/ Ground Foliage of weeds May only be used in CA Max w

aerial a

1

80289-5/ 

STRADA® 

CA 

50.0 WDG 0.067 

Broadcast to 

foliage/ wet and 

dry seeded rice 

Aircraft / 

Ground 

For dry seeded rice, 

early postemergence 

to pre-flood. For 

wet-seeded rice, 

early postemergence 

to middle-late 

postemergence 

May only be 

used in CA 

Drain r

app. 

approv

or su

recom

AR080012/ 

STRADA 

WG 

50.0 WDG 0.067 Broadcast Aircraft Foliar May only be used in AR 

Spray b

may no

feet / 

larger D

LA080007/ 

STRADA 

WG 

50.0 WDG 0.067 Broadcast Aircraft Foliar May only be used in LA 

MO080002

/ STRADA 

WG 

50.0 WDG 0.067 Broadcast Aircraft Foliar May only be used in MO 

TX080007/ 

STRADA 

WG 

50.0 WDG 0.067 Broadcast Aircraft Foliar May only be used in TX 

Abbreviations: Form=formulation; Max=maximum; WDG=water dispersable granule; WG=wettable granule; App=application; DSD=a Packaged with another herbicide product, QuinStar® Herbicide, containing 75% quinclorac. The co-pack is made to be used as a tan
9 

According to the February 3, 2011 “Screening Level Estimates of Agricultural Uses of 

Orthosulfamuron” provided by the Biological and Economic Analysis Division (BEAD), the 

amount of orthosulfamuron used on rice is 2,000 lbs per year2

, a very low application rate 

relative to those for many other herbicides. The percent crop treated was less than 2.5 percent in 

a given year3. Rice is primarily grown in California, Texas, Louisiana, Arkansas, Mississippi, 

and Missouri and orthosulfamuron was primarily used in Arkansas, Missouri, and California 

(USEPA, 2010a). To identify those states with less rice production “Quick Stats” from the 

National Agricultural Statistics Service4 was searched for states where rice was harvested in 

2007. In addition to the primary rice growing states, rice was also harvested in Florida, 

Tennessee, Texas, and Oklahoma. Figure 1 shows the acres planted in rice by county for 

selected states in 2009. These are the areas where the highest amounts of rice are grown in the 

United States and thus the areas where orthosulfamuron would most likely be used. 

 Figure 1. Acres Planted in Rice by County for Selected States in the United States. Prepared by the National 

Agricultural Statistics Service (NASS) and downloaded from 

http://www.nass.usda.gov/Charts_and_Maps/Crops_County/ar-pl.asp

Limitations stated on orthosulfamuron labels that are relevant to the ecological risk assessment 

are listed in Appendix I. 

 

2

 Estimated as an average across 2001-2010 and then rounded. 

3

 This is the maximum value reported across all data sources and all years. 4 http://quickstats.nass.usda.gov/results/90ECABCD-EAC2-3285-A03A-121D372EE6A6
10 

VI.  Environmental Fate and Transport

Summary 

Orthosulfamuron will enter the environment via spray directly onto soil, foliage, or water of rice 

paddies. It may move off-site via spray drift, leaching, runoff, and release of paddy water. 

Orthosulfamuron has five estimated pKa values. Its solubility increases with pH. 

Orthosulfamuron is considered semivolatile from dry non-adsorbing surfaces and non-volatile 

from water and moist soil. It is not likely to bioconcentrate in aquatic or terrestrial organisms. 

Chemicals with half-lives greater than 60 days in soil, water, and sediment are considered 

persistent (USEPA, 2008b). The range of half-lives for orthosulfamuron fall into both the 

persistent and nonpersistent categories. The primary routes of degradation are via hydrolysis, 

aerobic aquatic, and anaerobic aquatic metabolism. Soil metabolism studies are not available. 

Seven major degradates have been observed in environmental fate studies, one of which is 

structurally similar to the parent (i.e., retains the sulfonylurea moiety) and the others are formed 

by splitting the parent molecule, effectively removing the sulfonylurea moiety. Identification of 

which degradates are residues of concern and the pathways of formation of the degradates is 

discussed in Section XI. Identification of Stressors of Concern. Many of the submitted studies 

are considered supplemental and data are still needed to fully understand the environmental fate 

of orthosulfamuron and its degradates. 

Fate Description 

Table 2 summarizes the identity information and physical-chemical properties of 

orthosulfamuron. Table 3 summarizes other environmental fate data. A more complete 

discussion of the environmental fate studies is available in Appendix A. Orthosulfamuron will 

enter the environment via spray directly onto soil, foliage, or water. It may move off-site via 

spray drift, leaching, and runoff, especially during rainfall events. Orthosulfamuron is predicted 

to have five dissociation constants (pKa of -1.4, 0.7, 3.5, 9.6, and 11.5) (MRID 46219011). The 

vapor pressure indicates that some may move offsite via volatilization from dry non-adsorbing 

surface, which could occur with application onto dry soil, as it is classified as a semivolatile 

compound using OPPTS5

 Guideline 835.6100 classification; however, this is expected to be a 

minor transport pathway. It is classified as non-volatile from water and moist soil. 

Orthosulfamuron’s water solubility increases with pH and has a very wide range over 

environmentally relevant pHs (26 mg/L at pH 4.0 and 38,900 at pH 8.5, both measured at 20o

C, 

MRID 446219009). Log octanol-water partition coefficients (Kow) range from 2.02 at pH 4 to 

<0.3 at pH 10 at 20o

C (MRID 46219012). 

 

5

 Office of Prevention, Pesticides, and Toxic Substances (OPPTS) is now the Office of Chemical Safety and 

Pollution Prevention (OCSPP); however, the guidelines still reference OPPTS and so the guidelines are referenced 

with OPPTS in this document. 
11 

Table 2. Summary of physical-chemical properties of orthosulfamuron1 

Parameter Value and Units Source and/or Comment

PC Code 108209 (USEPA, 2006, D333514) 

CAS Number CAS 213464-77-8 (USNLM, 2009) 

SMILES Code c1cccc(c1NS(=O)(=O)NC(Nc1nc(cc(n1)OC)

OC)=O)C(=O)N(C)C 

(NCI/CADD Group, 2011) 

Chemical Name 1-(4,6-dimethoxypyrimidin-2-yl)-3-[2-

(dimethylcarbamoyl)phenylsulfamoyl]urea 

(IUPAC) 

(USEPA, 2006, D333514) 

Empirical 

Formula 

C16H20N6O6S (USEPA, 2006, D333514) 

Molecular 

Weight 

424.4 g/mole (USEPA, 2006, D333514) 

UV/Visible 

Absorption 

Significant absorbance observed below 300 

nm 

MRID 46559001; Acceptable 

Water Solubility pH 4.0 at 20o

C: 26 mg/L 

pH 7.0 at 20oC: 629 mg/L 

pH 8.5 at 20o

C: 38,900 mg/L 

MRID: 44621909; Acceptable 

Vapor Pressure <1.1 × 10-6 Torr at 25o

C 

8.37× 10-7 Torr at 20o

C 

<1.4 × 10-4 Pa at 25°C 

1.12 × 10-4 Pa at 20°C 

MRID: 46219010; Acceptable, Semivolatile 

from dry nonadsorbing surfaces 

Henry’s Law 

constant 

pH 4, 1.8 x 10-8 atm-m3

/mol 

pH 7, 7.4 x 10-10 atm-m3

/mol 

pH 8.5, 1.2 x 10-11 atm-m3

/mol 

Estimated from vapor pressure 

and water solubility at 20o

C. 

Dissociation 

Constant (pKa) 

-1.4, 0.7, 3.5, 9.6, and 11.5 MRID: 46219011; Acceptable, estimated using 

ACD/I-LAB Web Service 

Log Kow pH 4: 2.02 

pH ~7: 1.31 

pH 10: <0.3 

MRID: 46219012; Acceptable. Temperature 

not reported. Not likely to bioconcentrate. 

Air-water 

partition 

coefficient 

(KAW) 

pH 4: 7.35 x 10-7 (log KAW = -6.13) 

pH 7: 3.04 x 10-8 (log KAW = -7.52) 

Estimated from vapor pressure 

and water solubility at pH 7 and 20oC. Nonvolatile from water. 

Octanol-air 

partition 

coefficient (KOA) 

pH 4: 1.4 x 108 (log KOA = 8.2) 

pH 7: 6.7 x 108 (log KOA = 8.8) 

Estimated from KAW and KOW. Potential to 

accumulate in terrestrial organisms only at pH 

4 and only if transformation is low.2

 

Therefore, it is unlikely to accumulate in 

terrestrial organisms. 

Cwater+soil/Cair pH 4: 2.96 x 106

 to 2.74 x 107

pH 4: 7.17 x 107 to 6.64 x 108

Estimated from KAW, r of 6, and range of 

measured Kd values. Non-volatile from moist 

soil 1

All estimated values were estimated according to “Guidance for Reporting on the Environmental Fate and 

Transport of the Stressors of Concern in Problem Formulations for Registration Review, Registration Review Risk 

Assessments, Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other Relevant Risk 

Assessments” (USEPA, 2010b). 

2 A recent scientific advisory panel (SAP) reported, “Gobas et al (2003) concluded that chemicals with a log KOA > 

5 can biomagnify in terrestrial food chains if log KOW >2 and the rate of chemical transformation is low. However, 
12 

further proof is needed before accepting these limits without reservations” (USEPA, 2009b). This was also 

supported by Armitage and Gobas’s work completed in 2007 (Armitage and Gobas, 2007). 

Table 3. Summary of other environmental fate and transport properties of 

orthosulfamuron. 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Hydrolysis5

Half-life, SFO linear regression1

: 

pH 7 at 25o

C: 24.4 days 

pH 9 at 25o

C: 228 days 

pH 4 at 50o

C: 0.02 days 

pH 7 at 50o

C: 1.5 days 

pH 9 at 50o

C: 8.0 days 

MRID 46219015 

(supplemental) 

Values may be used in risk 

assessment. Values measured at 

50o

C are not used in modeling but 

show that degradation is more 

rapid at pH 4 than at pH 7 and 9. 

Half-life, SFO linear regression1: 

pH 4 at 50o

C: 0.02 days 

pH 7 at 50o

C: 1.2 days 

pH 9 at 50o

C: 8.6 days 

MRID 46219016 

(supplemental) 

May be used quantitatively but not 

for use in modeling as the 

temperature is not environmentally 

relevant. 

Atmospheric 

Degradation 

Half-life: 

0.049 days (estimated) 

Estimated Using 

EPIWeb Version 

4.0 see Appendix 

A. 

Not likely to undergo long range 

transport in vapor phase.3

Aqueous 

Photolysis 

Stable MRID 46588509 

(supplemental) 

Study had many deficiencies but 

was adequate to show that 

photolysis was not a significant 

degradation pathway. 

Soil Photolysis No data submitted Not applicable None 

Aerobic Soil 

Metabolism 

No data submitted Not applicable None 

Anaerobic Soil 

Metabolism 

No data submitted Not applicable None 

Aerobic Aquatic 

Metabolism 4

Half-life, SFO linear regression1

, at 

20o

C: 

Parent Only 

40.6 and 36.3 (AR, loam soil pH 6.9-

7.25, water pH 7.8-6.81) 

24.1 and 21.3 days (CA, clay soil pH 

6.0-6.97, water pH 7.7-7.03) 

Parent+ Unextracted residues: 

70.5 and 59.2 (AR, loam soil pH 6.9-

7.25, water pH 7.8-6.81) 

65.4 and 30.3 days (CA, clay soil pH 

6.0-6.97, water pH 7.7-7.03) 

MRID 46219017 

(supplemental) 

Total system half-lives are shown 

for different rings labeled. 

Unextracted residues ranged from 

not detected to 33% applied 

radioactivity. Reasonable attempt 

to extract all residues was not 

made. Rate may be adjusted to 

standard temperature of 25o

C for 

modeling. 
13 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Anaerobic 

Aquatic 

Metabolism 

Half-life, SFO linear regression1, at 

20oC: 

Parent Only: 

80 and 89 days (AR water-loam soil 

pH 6.9-7.45, water pH 7.8-7.44) 

41 and 41 days (CA pond-water clay 

soil pH 6.0-6.72, water pH 7.7-6.82) 

Parent+Unextracted Residues: 

142 and 217 days (AR water-loam 

soil pH 6.9-7.45, water pH 7.8-7.44) 

88 and 161 days (CA pond-water clay 

soil pH 6.0-6.72, water pH 7.7-6.82) 

MRID 46578967 

(supplemental) 

Several deficiencies. Not 

appropriate for use in modeling. 

Rate may be adjusted to standard 

temperature of 25o

C for 

modeling.6

 

Sorption 

coefficients 

Solid-water distribution Coefficient, 

Kd in L/kg 

6.1, sandy loam, pH 6.3, 1.13%OC 

8.6, silt loam, pH 5.7, 2.03%OC 

6.3, silt loam, pH 6.8, 1.00%OC 

6.1, clay loam, pH 6.1, 2.60% OC 

Organic-carbon normalized 

distribution coefficient, KOC in L/kgOC: 

532, sandy loam, pH 6.29, 1.13%OC 

425, silt loam, pH 5.71, 2.03%OC 

626, silt loam, pH 6.78, 1.00%OC 

266, clay loam, pH 6.11, 2.60% OC 

MRID 46219074 

(supplemental) 

May be used quantitatively. 

Solid-water distribution Coefficient, 

Kd in L/kg 

2.5, sandy loam, pH 6.5, 1.04% OC 

7.5, sandy loam, pH 5.6, 0.35% OC 

3.2, sand, pH 4.70, 1.03% OC 

20.7, clay loam, pH 5.4, 3.01% OC 

2.0, silt loam, pH 7.5, 0.92% OC 

7.0, loam, pH 7.4, 1.8% OC 

Organic-carbon normalized 

distribution coefficient, KOC in L/kgOC: 

238, sandy loam, pH 6.5, 1.04%OC 

2145, sandy loam, pH 5.6, 0.35% OC 

307, sand, pH 4.7, 1.03% OC 

687, clay loam, pH 5.4, 3.01% OC 

215, silt loam, pH 7.5, 0.92% OC 

389, loam, pH 7.4, 1.8% OC 

MRID 46578971 

(supplemental) 

May be used quantitatively. The 

coefficient of variation(CV) for all 

Kd values was 76%, 98% for all 

KOC values, when the outlying 

high Kd and KOC are removed for 

the soil with an OC content of 

0.35%, the CV was 81% for Kd 

values and 42% for KOC values. 
14 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Aged Column 

Leaching 

Orthosulfamuron not observed in 

leachate but was observed in Segment 

D (21 cm depth). DBS-acid, DBS 

amide, DB amine, o-desmethyl 

orthosulfamuron, DOP urea, DOP 

amine, and o-desmethyl DOP urea 

were all detected at lower segments as 

well. 

MRID 46219018 

(acceptable) 

None 

Soil Column 

Leaching 

Orthosulfamuron was the only 

compound found in leachate and 

lower soil segments. DOP urea was 

found in top 0-25 cm of soil and DOP 

amine was not detected in one soil but 

was detected in another. Movement 

through the column indicates that it 

has the potential to move through soil 

in environment. 

MRID 46578968 

(supplemental) 

May be used quantitatively. 

Arkansas sandy loam soil and 

North Dakota sand soil. 

Aquatic Field 

Dissipation 

Dissipation SFO Half-life2, linear 

regression1

Arkansas Site (pH 6.7): 

4.1 days (soil) 

6.2 days (sediment) 

6.4 days (water) 

California Site (pH 7.7): 

2.3 days (soil) 

4.3 days (sediment) 

Not calculated (water) 

MRID 46578985 

(supplemental) 

Associated ECM and ILV are not 

available for soil/sediment and 

water. Field spikes were prepared 

for water, soil, and sediment at one 

sampling interval. These values 

may underestimate the field halflives and should be considered 

with an understanding of the data 

limitations. See AppendixA. 

Steady State 

Bioconcentration 

Factor 

Measured at 135.2 μg/L at 22-23oC in 

Bluegill Sunfish (Lepomis 

macrochirus): 

0.29 L/kg wet weight, edible tissue 

0.34 L/kg wet weight, nonedible 

tissue 

32 L/kg wet weight, whole fish 

16 – 29 L/kg-lipid 

Measured at 1391-1550 μg/L at 22-

23o

C: 

0.72 L/kg wet weight, edible tissue 

1.14 L/kg wet weight, nonedible 

tissue 

0.97 L/kg wet weight, whole fish 

52-68 L-kg-lipid 

46588507 

(acceptable) 

None 

Environmental 

Chemistry 

Method: Water 

None submitted NA None 
15 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Environmental 

Chemistry 

Method: Soil 

and Sediment 

None submitted NA None 

Abbreviations: ECM=Environmental Chemistry Method; ILV=Independent Laboratory Validation; SFO=Single 

First Order 

1

Degradation kinetics were calculated using the single first order (SFO) decay equation using either nonlinear 

regression of non-transformed data or linear regression of natural log-transformed data. 

2

 The half-life value may reflect both dissipation and degradation processes. 

3

 The minutes of the Scientific Advisory Panel examining issues related to persistent, bioaccumulative, and toxics 

states, “To protect against long range transport, a two-day degradation half-life in air is used internationally in 

regulations that identify persistent chemicals.” (USEPA, 2009b) 

4

 MRID 46588508 is an unacceptable aerobic aquatic metabolism study. 

5

 MRID 46578970 examined hydrolysis at pH 5 and 25oC. The study is unacceptable. 

6 The anaerobic aquatic metabolism study was conducted using a soil and unextracted residues made up as much as 

43% of applied radioactivity. The degradate profile could change if the identity of the unextracted residues were 

known. Additional data provided on anaerobic aquatic metabolism would allow EFED to more accurately predict 

the rate of anaerobic aquatic metabolism when estimating surface water concentrations.

Orthosulfamuron may be persistent in some aquatic systems and non-persistent in other aquatic 

systems.6

 Hydrolysis rates at pH 7 and aerobic aquatic metabolism rates for parent alone 

indicate that orthosulfamuron is not persistent in aerobic aquatic environments. However, 

hydrolysis rates at pH 9, anaerobic aquatic half-lives and aerobic aquatic half-lives considering 

both the parent and unextracted residues indicate that orthosulfamuron may be persistent in some 

aquatic environments. 

Hydrolysis rates decrease as pH increases (half-life =24 days at pH 7 and 228 days at pH 9 at 

25oC). A hydrolysis rate at an acidic pH is not available at 25oC. Limited data are available to 

understand the behavior of orthosulfamuron in the presence of light as the available aqueous 

photolysis study did not compare the light intensity to natural sunlight; however, the available 

data are adequate to show that aqueous photolysis is not a significant degradation pathway as 

only 6% was lost when exposed to wavelengths where absorbance was observed for seven days 

(MRID 46588509). Soil photodegradation data are not available. 

Data are not available examining aerobic and anaerobic soil metabolism rates. Orthosulfamuron 

did undergo biodegradation in both aerobic and anaerobic aquatic environments. Aerobic 

aquatic metabolism half-lives ranged from 21 to 41 days at 20o

C in two sediments (MRID 

46219017) and anaerobic aquatic half-lives ranged from 41 to 89 days at 20o

C in two soils 

(MRID 46578967). It is not known whether a portion of the unextracted residues, which made 

up a maximum of 43% of applied radioactivity, were the parent compound or degradates of 

concern; therefore half-lives were also calculated assuming that unextracted residues were the 

parent. Aerobic aquatic metabolism half-lives calculated assuming that unextracted residues 

were the parent ranged from 30 to 71 days at 20oC in two sediments (MRID 46219017) and 

anaerobic aquatic half-lives ranged from 88 to 217 days at 20o

C in two sediments (MRID 

46578967). Hydrolysis, which varies with pH, may have contributed to some of the degradation 

 

6

 International half-lives that are considered persistent in soil, water, and sediment range from greater than 60 days 

to greater than 365 days (USEPA, 2008b). 
16 

observed in these studies and this will be considered when using these rates in modeling. 

Orthosulfamuron’s aerobic and anaerobic aquatic half-lives indicate that a small percentage of 

applied orthosulfamuron (~0-31%) may remain in soil/sediment 365 days after application; 

therefore, some accumulation may occur with successive annual applications. Supplemental 

aquatic field dissipation half-lives ranged from two to six days when orthosulfamuron was 

applied to bare ground plots in California (pH 7.7) and Arkansas (pH 6.7) followed by flooding 

(MRID 46578985). Time to ninety percent dissipation ranged from 8 to 21 days. The results are 

questionable as the results from field spikes indicated that some compounds were not stable in 

field spiked soil samples (percent recovery ranged from 16-100%) and validated environmental 

chemistry methods are not available.7 Maximum concentrations of orthosulfamuron and 

transformation products observed in the study are reported in Appendix J. 

Orthosulfamuron is classified as moderately mobile to slightly mobile with organic carbon 

normalized soil-water distribution coefficients (Koc) values ranging from 215 – 2,145 L/kg-OC 

measured in ten soils (MRID 46578971; USEPA, 2010b). Based on orthosulfamuron’s water 

solubilities and estimated pKa values, its affinity to organic materials (and thus KOC values) are 

expected to increase with pH; however, KOC values were not correlated to pH and available 

sorption coefficients did not show a trend with pH. This is likely due to the limited data set that 

does not provide enough information to fully understand the influence of various soil/sediment 

constituents on sorption. It has the potential to reach ground water, especially in vulnerable 

alkaline soils with low organic-carbon content and/or the presence of shallow ground water. 

Based on the high water solubility (629 mg/L at pH 7 and 20oC) and the low Koc values, a higher 

percentage of orthosulfamuron will be found in water as compared to sediment. As its solubility, 

sorption coefficients, and hydrolysis are influenced by its association state and pH, a higher 

percentage will be found in water under higher pH conditions. 

Based on the log Kow (<0.3 – 2.02) and measured bioconcentration factors in bluegill Sunflish 

(Lepomis macrochirus, BCFs, lipid normalized values range from 16 to 68 L/kg-lipid), 

orthosulfamuron is not likely to bioconcentrate in aquatic organisms. Orthosulfamuron’s vapor 

pressure is just high enough to be between the classifications of non-volatile under field 

conditions to intermediate to high volatility under field conditions, using the OPPTS Guideline 

835.6100 classification system. Thus, it is considered a semivolatile compound from dry nonadsorbing surfaces. Based on the Henry’s law-constant, air-water partition coefficient (KAW), 

and solid-water distribution coefficients (Kd), it is classified as non-volatile from water and moist 

soil (USEPA, 2010b). The estimated KOA value (1.4 x 108 at pH 4 and 6.7 × 10-8 at pH 7), 

combined with the log Kow at pH 4 indicate that orthosulfamuron may have the potential to 

accumulate in terrestrial organisms at low pH conditions8,9; however, this potential is only 

 

7

 This study would be more reliable with a complete ILV of the ECMs and if results from field spikes collected at 

each sampling interval were provided. Field spiked samples were only collected at one sampling event and the 

percent recoveries were variable and often low. It is not known if the results of the field spikes for the one sampling 

event are applicable to other sampling events and whether it is appropriate to correct all samples using the field 

spikes from one sampling interval. Finally, the LOQ for the ECM in water was higher than that necessary to detect 

levels that could result in a risk concern (0.02 μg/L) and not all major degradates were looked for in the samples. 

Therefore, the study is not upgradeable to acceptable but may be adequate to assess risk if the ECM and field spike 

recoveries issues are resolved. 

8

 The pH of precipitation may be as low as 4.2 (see USGS National Water Conditions; 

http://water.usgs.gov/nwc/NWC/pH/html/ph.html) and the pH of surface water ranges from 5-10 (USGS Continuous 
17 

observed at low pH where a rapid hydrolysis is expected. Therefore, accumulation in terrestrial 

organisms is not likely to be a risk concern. 

The transformation products resulting from the environmental degradation processes of 

orthosulfamuron are: 

• 2-dimethylcarbamoylphenyl sulfamic acid (DBS acid; IR7863; S1); 

• 2-sulfamoylamino-N,N-dimethylbenzamide (DBS amide; S2); 

• 2-amino-N,N-dimethylbenzamide (DB amine; S4); 

• 1-(4-hydroxy-6-methoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl) 

phenylsulfamoyl]urea (o-desmethyl orthosulfamuron; IR8181; S9); 

• N-(4,6-dimethoxypyrimidin-2-yl)urea (DOP urea; IR7825; S12); 

• 4,6-dimethoxypyrimidin-2-yl amine (DOP amine; S13); and 

• N-(4-hydroxy-6-methoxypyrimidin-2-yl)urea (o-desmethyl DOP urea; S15). 

Two other degradation products S5 and S11 are composed of multiple unresolved compounds. 

Figure 2 shows the degradation pathway of orthosulfamuron. 

 Water Quality Watch; available at http://waterwatch.usgs.gov/wqwatch/). In rice growing areas, surface water pH 

ranged from 5-9 and precipitation pH was ≥4.7. 9

 A recent scientific advisory panel (SAP) reported, “Gobas et al (2003) concluded that chemicals with a log KOA > 

5 can biomagnify in terrestrial food chains if log KOW >2 and the rate of chemical transformation is low. However, 

further proof is needed before accepting these limits without reservations” (USEPA, 2009b). This was also 

supported by Armitage and Gobas’s work completed in 2007 (Armitage and Gobas, 2007). 
Figure 2

40). Abb

DBS aci

were the

observed

the final 

observed

of residu

it is like

dissipatio

orthosulf

both sites

sediment

major de

structure

maximum

 

10 Major de

2. Degradat

breviations 

d, DB amin

e major degr

d for each id

sampling in

d. Additiona

ues were une

ely that som

on study te

famuron. Os. At the Ar

t; DBS acid 

egradate in s

s of these de

m amounts o

 

egradates are th

tion Pathwa

are defined

ne, DOP am

radates.10 T

dentified tran

nterval and 

ally, up to 33

xtracted and

me of these

est sites w

-desmethyl o

rkansas site,

was the maj

soil and sed

egradation pr

observed in l

 

hose present at

ay of Orthos

d in text abo

mine, DOP u

Table 4 sho

nsformation 

if the study

3% of residu

d therefore, u

e maximum 

were analyze

orthosulfam

, DOP urea 

jor degradate

diment; no m

roducts are s

laboratory fa

t ≥10% applied

18 

sulfamuron 

ove figure. 

urea, DBS am

ows the max

product. M

y was extend

ues in the aer

unidentified.

percentage

ed for DO

muron was be

and DBS ac

e in water. 

major degrad

shown in Ap

ate studies. 

d parent equiva

(adapted fr

mide, and o

ximum amo

Many of the m

ded; higher 

robic aquati

. If all resid

es would in

OP urea, D

elow detectio

cid were maj

At the Calif

dates were d

ppendix J al

alents. 

rom MRID 

o-desmethyl 

ount of appl

maximums w

percentages

c metabolism

dues were ful

ncrease. Bo

BS acid, a

on limits in 

jor degradate

fornia site, D

detected in w

long with m

46588508, p

orthosulfam

lied radioac

were observ

s may have 

m study and

lly character

oth aquatic

and o-desm

all samples 

es in the soi

DOP urea wa

water. Chem

ore details o

page 

muron 

tivity 

ved at 

been 

d 43% 

rized, 

field 

methyl 

from 

il and 

as the 

mical 

on the 
19 

Table 4. Summary of maximum amount of transformation products observed in fate 

studies.

Transformation 

Product Study Type MRID Maximum %AR (day) Final %AR (study length) 

DBS Acid 

Hydrolysis 46219015 

58 ( 37 days, pH 7, 25o

C) 

23 (176 days, pH 9, 25o

C) 

86 (5 days, pH 4, 50o

C) 

66 (5 days, pH 7, 50oC) 

12 (5 days, pH 9, 50o

C) 

58 ( 37 days, pH 7, 25o

C) 

23 (176 days, pH 9, 25o

C) 

86 (5 days, pH 4, 50o

C) 

66 (5 days, pH 7, 50oC) 

12 (5 days, pH 9, 50o

C) 

Aerobic Aquatic 46219017 61 (61 days, CA phe) 61 (61 days, CA phe ) 

Anaerobic aquatic 46578967 39 (150 days, CA pyr) 39 (150 days, CA pyr) 

DB Amine 

Hydrolysis 46219015 

2 (37 days, pH 7, 25o

C) 

13 (176 days, pH 9, 25o

C) 

13 (5 days, pH 4, 50o

C) 

11 (5 days, pH 7, 50oC) 

6 (5 days, pH 9, 50o

C) 

2 (37 days, pH 7) 

13 (176 days, pH 9) 

13 (5 days, pH 4, 50o

C) 

11 (5 days, pH 7, 50oC) 

6 (5 days, pH 9, 50o

C) 

Aerobic aquatic 46219017 1 (90 days, CA sediment) 1 (90 days, CA sediment) 

Anaerobic aquatic 46578967 6 (42 days, AR phe) 5 (42 days, AR phe) 

DOP amine 

Hydrolysis 46219016 

4 (1hr, pH 4, 50o

C) 

11 (52 hrs, pH 7, 50oC) 

53 (13 days, pH 9, 50o

C) 

4 (1hr, pH 4, 50o

C) 

11 (52 hrs, pH 7, 50oC) 

53 (13 days, pH 9, 50o

C) 

Aerobic aquatic 46219017 1 (90 days, AR sediment) 1 (90 days, AR sediment) 

Anaerobic Aquatic 46578967 <1 (100 days, AR pyr) <1 (180 days, AR pyr) 

DOP urea 

Hydrolysis 46219016 

78 (1hr, pH 4, 50o

C) 

60 (52 hrs, pH 7, 50o

C) 

13 (13 days, pH 9, 50oC) 

78 (1hr, pH 4, 50o

C) 

60 (52 hrs, pH 7, 50o

C) 

13 (13 days, pH 9, 50oC) 

Aerobic Aquatic 46219017 47 (90 days, AR pyr) 47 (90 days, AR pyr) 

Anaerobic Aquatic 46578967 19 (59 days, CA pyr) 16 (150 days, CA pyr) 

DBS amide 

Hydrolysis 46219015 

7 ( 37 days, pH 7, 25o

C) 

8 (176 days, pH 9, 25oC) 

9 (0.13 days, pH 4, 50oC) 

8 (2 days, pH 7, 50o

C) 

10 (5 days, pH9, 50oC) 

7 ( 37 days, pH 7, 25o

C) 

8 (176 days, pH 9, 25oC) 

1 (0.04 days, pH 9, 50oC) 

5 (5 days, pH 7, 50o

C) 

10 (5 days, pH9, 50oC) 

Anaerobic aquatic 46578967 4 (180 days, AR phe) 4 (180 days, AR phe) 

Aerobic aquatic 46219017 4 (90 days, AR phe) 4 (90 days, AR phe) 

O-desmethyl 

orthosulfamuron 

Aerobic aquatic 46219017 9 (90 days, AR pyr) 9 (90 days, AR pyr) 

Anaerobic Aquatic 46578967 19 (100 days, AR phe) 16 (180 days, AR phe) 

17 (180 days, AR pyr) 17 (180 days, AR pyr) 

O-desmthyl DOP 

urea 

Aerobic aquatic 46219017 4 (44 days, CA) 3 (90 days, CA) 

Anaerobic aquatic 46578967 3 (180 days, AR pyr) 3 (180 days, AR pyr) 

A. Monitoring Data

The following databases and sources were searched for monitoring information on 

orthosulfamuron on July 5, 2011: 
20 

• The United States Environmental Protection Agency (USEPA) STORET Database 

(http://www.epa.gov/storet/dbtop.html) 

• The United States Geological Survey (USGS) National Water-Quality Assessment 

(NAWQA) Program Data Warehouse 

(http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567) 

• The USGS National Stream Quality Accounting Network (NASQAN) program 

(http://water.usgs.gov/nasqan/) 

• Sampling for Pesticides Residues in California Well Water Cumulative Report; EEH03-

08; December 2003 (http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/eh0308.pdf) 

• California Department of Pesticide Regulation (DPR) Surface Water Database 

(http://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm) 

No monitoring data are available as none of the databases reported looking for orthosulfamuron. 

B.  Clean Water Act

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

impaired under section 303(d) of the Clean Water Act, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88

5. In addition, no Total Maximum Daily Loads (TMDL) have been developed for the herbicide, 

based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id

=885&p_pollutant_group_name=PESTICIDES. More information on impaired water bodies and 

TMDLs can be found at http://www.epa.gov/owow/tmdl/. 

The Agency invites submission of water quality data for this pesticide. To the extent possible, 

data should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assessments. 

VII.  Receptors

Consistent with the process described in the Overview Document (USEPA, 2004), the risk 

assessment will rely on a surrogate species approach. Toxicological data generated from 

surrogate test species, which are intended to be representative of broad taxonomic groups, are 

used to extrapolate to potential effects on a variety of species (receptors) included under these 

taxonomic groupings. The most sensitive endpoint for each taxon is evaluated. Assessment 

endpoints include direct toxic effects on the survival, reproduction, and growth of terrestrial and 

aquatic life, as well as indirect effects, such as reduction in prey base and/or modification of 

habitat. The evaluated taxa include freshwater fish, freshwater aquatic invertebrates, birds, small 

mammals, terrestrial invertebrates, algae, and terrestrial plants. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature are used to evaluate the potential direct and indirect effects on aquatic 
21 

and terrestrial receptors. These data include studies on the technical grade active ingredient, 

degradates, and formulated products (e.g. “six-pack” acute toxicity studies). The open literature 

studies are identified using EPA’s ECOTOX database, which employs a literature search engine 

for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife (USEPA, 

2009a). The evaluation of both sources of data can also provide insight into the direct and 

indirect effects of orthosulfamuron on biotic communities from loss of species that are sensitive 

to the chemical and from changes in structure and functional characteristics of the affected 

communities. 

A search using EPA’s ECOTOX database will be performed as a routine course of action for risk 

assessment for orthosulfamuron. 

Acute (short-term) and chronic (long-term) toxicity information is characterized based on 

registrant-submitted studies and a comprehensive review of the open literature on 

orthosulfamuron. Other sources of information, including use of the acute probit dose-response 

relationship to establish the probability of an individual effect and reviews of the Ecological 

Incident Information System (EIIS), are conducted to further refine the characterization of 

potential ecological effects associated with exposure to orthosulfamuron. A summary of the 

available ecotoxicity information and the incident information for orthosulfamuron are provided 

below. 

Table 5 provides a summary of the most sensitive surrogate species tested to characterize the 

potential acute and chronic ecological effects of orthosulfamuron. Interestingly, rice is the most 

sensitive monocot plant (seedling emergence test). 

Table 5. Most Sensitive Species Evaluated for Potential Ecological Effects from 

Orthosulfamuron. 

Exposure Scenario Species 

Acute Toxicity 

-- 

Chronic Toxicity 

Citation 

MRID 

Acute Toxicity 

Classification 

Birds1

Acute 

(Dose-based) 

Mallard duck 

(Anas 

platyrhynchos) 

and 

Bobwhite Quail 

(Colinus 

virginianus) 

LD50 >1960 mg a.i./kg-bw Single oral dose 

46260107 

(Acceptable) 

Slightly Toxic 

Chronic 

 Mallard duck 

and 

Bobwhite Quail3

NOAEC = 1280 mg a.i./kgdiet

Avian reproduction 

46578949 

(Duck-Acceptable) 

46578950 

(Quail-Acceptable) 

-- 

Mammals 

Acute 

Laboratory rat 

(Rattus norvegicus) 

LD50>5000 mg a.i./kg-bw 

Single oral dose 

46219019 

(Acceptable) 

Practically 

Non-toxic 

Chronic 

NOAEL (changes in body wt, 

hepatotox, nephrotox) = 5 

mg/kg/day or 100 mg/kg-diet 

Chronic Toxicity 

Study 

MRID 46578913 

(Acceptable) 

-- 
22 

Exposure Scenario Species 

Acute Toxicity 

-- 

Chronic Toxicity 

Citation 

MRID 

Acute Toxicity 

Classification 

Insects 

Acute (contact) 

Honey bee 

(Apis mellifera L.) 

LD50>100 ug a.i./bee 

48-Hour 

46219046 

(Acceptable) Practically 

Non-toxic 

Acute (oral) LD50>109.4 ug a.i./bee 

48-Hour 

46219046 

(Supplemental) 

Freshwater fish2

Acute 

Rainbow Trout 

(Oncorhynchus 

mykiss)

LC50>122 mg a.i./L 

96-Hour 

46219042 

(Acceptable) 

Practically 

Non-toxic 

Chronic 

Fathead Minnow 

(Pimephales 

promelas) 

NOAEC (dry wt) 

= 6.1 mg a.i./L 

Early Life Stage 

46578953 

(Acceptable) 

-- 

Freshwater Invertebrates

Acute Water Flea 

(Daphnia magna) 

EC50 (mortality/immobility) 

 > 97.3 mg a.i./L 

48-Hour 

46219044 

(Acceptable) 

Practically 

Non-toxic 

Chronic Water Flea 

(Daphnia magna) 

NOAEC (total length) 

= 6.5 mg a.i./L 

21-Day 

46578956 

(Acceptable) 

-- 

Estuarine/Marine Fish

Acute 

Sheepshead 

Minnow 

(Cyprindon 

varigatus) 

LC50>123 mg a.i./L 

96-Hour 

46578951 

(acceptable) 

Practically 

Non-toxic 

Chronic *No studies available* 

Estuarine/Marine Invertebrates

Acute 

Eastern Oyster 

(Crassostrea 

virginica) 

EC50>97 mg a.i./L 

96-Hour 

46578957 

(Acceptable) 

Slightly Toxic 

Chronic 

Mysid Shrimp 

(Americamysis 

bahia) 

NOAEC = 27 mg a.i./L 

29 Days 

46578954 

(Supplemental) 

-- 

Terrestrial Plants 

Monocot 

Rice 

(Oryza sativa) 

EC25 (dry wt) = 0.078 lb 

a.i./A 

---- 

NOAEC = 0.0436 lb a.i./A 

Seedling Emergence 

46578941 

(Acceptable) NA 

Onion 

(Allium cepa)

EC25 (dry wt)=0.0048 lb 

a.i./A 

---- 

NOAEC = 0.00169 lbs a.i./A 

Vegetative Vigor 

46578942 

(Supplemental) NA 

Dicot 

Radish 

(Raphanus sativus) 

EC25=0.040 lb a.i./A 

---- 

NOAEC = 0.015 lb a.i./A 

Seedling Emergence 

46578941 

(Acceptable) 

NA 

Carrot 

(Daucus carota) 

EC25 = 0.00012 lb a.i./A 

EC05 = 0.000027 lb a.i./A 

---- 

NOAEC < 0.0000664 

Vegetative Vigor 

46578942 

(Supplemental) 

NA 

Aquatic Plants 

Aquatic vascular 

Plants 

Duckweed 

(Lemna gibba) 

EC50 (frond number) =0.0007 

mg a.i./L 

------- 

NOAEC = 0.00026 mg a.i./L 

7-Day Study 

46578939 

(Acceptable) 

NA 

EC50 (frond number) = 7-Day Study NA 
23 

Exposure Scenario Species 

Acute Toxicity 

-- 

Chronic Toxicity 

Citation 

MRID 

Acute Toxicity 

Classification 

0.00075 mg a.i./L 

---- 

NOAEC = 0.00022 mg a.i./L 

46578940 

(Acceptable) 

Marine Algae4 Marine Diatom 

(Skeletonema 

costatum) 

EC50 (biomass) 

= 0.08 mg a.i./L 

------- 

NOAEC = 0.021 mg a.i./L 

46578936 

(Supplemental) NA 

1

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

 Freshwater fish may be surrogates for aquatic-phase amphibians. 3

 The NOAEC shown applies to both the mallard duck and bobwhite quail. 4

 The test material was IR5878 50WG containing 49.96% orthosulfamuron. 

A.  Effects to Aquatic Organisms

Summary 

Available ecotoxicity data indicate that orthosulfamuron is characterized as practically non-toxic 

to fish and aquatic invertebrates on an acute exposure basis. Many of the acute toxicity endpoints 

are non-definitive (i.e., “greater than” values) as no mortalities or effects were observed at the 

highest concentrations levels tested. Compared to aquatic animals, aquatic plants are orders of 

magnitude more sensitive to the herbicide orthosulfamuron. 

Freshwater Fish

Based on the most sensitive species of freshwater fish tested, i.e., rainbow trout (Oncorhynchus 

mykiss) with an 96-hr LC50>122 mg a.i./L, orthosulfamuron is classified as practically nontoxic 

to fish on an acute exposure basis. No sublethal effects on fish were reported in the acute 

toxicity studies. 

There are no studies assessing the acute toxicity of orthosulfamuron formulations or degradates 

in freshwater fish. 

A 33-day, early life-stage toxicity study of orthosulfamuron in fathead minnow was submitted by 

the registrant to establish the chronic toxicity of orthosulfamuron to freshwater fish (MRID 

46578953). Fish were monitored for embryo survival, larval survival, terminal length, dry 

weight, wet weight, and clinical signs of toxicity. Following chronic exposure (33 days) to 

fathead minnows (Pimephales promelas), the reported no observed adverse effect concentration 

(NOAEC) and lowest observed adverse effect concentrations (LOAEC) were 6.1 and 13 mg 

a.i./L, respectively, and were based on decreased growth (dry weight). The chronic NOAEC 

value of 6.1 mg a.i./L for effects on growth is the most sensitive chronic endpoint for freshwater 

fish. 

There are no chronic toxicity studies of orthosulfamuron formulations or degradates in 

freshwater fish. 

Freshwater Invertebrates 
24 

The waterflea (Daphnia magna) was the most sensitive freshwater invertebrate tested with a 48-

hr EC50>97.3 mg a.i./L. Based on this endpoint, orthosulfamuron is classified as slightly toxic to 

freshwater invertebrates on an acute exposure basis. No sublethal effects were noted in the acute 

toxicity study. 

There are no acute toxicity studies of orthosulfamuron formulations or degradates in freshwater 

invertebrates. 

A 21-day life-cycle toxicity study with orthosulfamuron with the water flea was used to establish 

the chronic toxicity of orthosulfamuron to freshwater. The NOAEC and LOAEC values of 6.5 

and 14 mg a.i./L, respectively, are based on reductions in growth (mean total length). In addition, 

first-generation survival was reduced at the highest concentration tested (NOAEC = 52 mg a.i./L; 

LOAEC = 105 mg a.i./L;). Reproduction and dry weight were not affected at any concentration 

tested. The NOAEC of 6.5 mg a.i./L is the most sensitive chronic endpoint for freshwater aquatic 

invertebrates exposed to orthosulfamuron. 

There are no chronic toxicity studies of orthosulfamuron formulations or degradates in 

freshwater aquatic invertebrates. 

Estuarine/Marine Fish 

The acute toxicity of orthosulfamuron to estuarine/marine fish was evaluated using the 

sheepshead minnow (Cyprindon varigatus). The study reported a 96-hour LC50 >123 mg a.i./L, 

indicating that orthosulfamuron is practically non-toxic to estuarine/marine fish on an acute 

exposure basis. No sublethal effects were observed in sheepshead minnow exposed up to 123 

mg a.i./L. No acute sublethal effects were observed in sheepshead minnow exposed to 

orthosulfamuron. 

No chronic toxicity studies in estuarine/marine fish with orthosulfamuron were submitted, thus, 

no information is available regarding the sublethal effects of chronic exposure of 

estuarine/marine fish to orthosulfamuron. There are no chronic toxicity tests in estuarine/marine 

fish with orthosulfamuron, formulations, or degradates. 

Estuarine/Marine Invertebrates

The most sensitive estuarine/marine invertebrate evaluated is the Eastern oyster (Crassostrea 

virginica) with a 96-hr EC50>97 mg a.i./L. An acute toxicity study with mysid shrimp resulted in 

a LC50>122 mg a.i./L. Based on these results, orthosulfamuron is characterized as slightly toxic 

to estuarine/marine invertebrates on an acute exposure basis. No sublethal effects were observed 

in acute toxicity studies with orthosulfamuron in the Eastern oyster. 

There are no acute toxicity studies of orthosulfamuron formulations or degradates in 

estuarine/marine invertebrates. 

One life-cycle (29-day) toxicity study with the mysid shrimp was submitted to establish the 

chronic toxicity of orthosulfamuron to estuarine/marine invertebrates. The NOAEC and LOAEC 

values of 27 and >27 mg a.i./L, respectively, were established for orthosulfamuron based on the 

absence of effects on mortality, reproduction, or growth after 29 days. The NOAEC of 27 mg 
25 

a.i./L is the most sensitive chronic endpoint for estuarine/marine invertebrates exposed to 

orthosulfamuron. 

There are no chronic toxicity studies of orthosulfamuron formulations or degradates in 

estuarine/marine invertebrates. 

Benthic Organisms 

There are no toxicity studies of orthosulfamuron TGAI, formulations, or degradates in benthic 

organisms. 

Aquatic Plants 

Studies were submitted for a freshwater vascular plant (duckweed, Lemna gibba), and for the 

nonvascular aquatic plants cyanobacteria (Anabaena flos-aquae), a freshwater diatom (Navicula 

pelliculosa), a green algae (Pseudokirchneriella subcapitata; formerly known as Selenastrum 

capricornutum), and a marine diatom (Skeletonema costatum) exposed to the formulated end-use 

product (EP), IR5878 50WG (water dispersible granule formulation containing approximately 

50% orthosulfamuron). 

Exposure of duckweed to orthosulfamuron TEP resulted in an 7-day EC50 value of 0.7 μg a.i./L 

and a NOAEC of 0.26 μg a.i./L for use in assessing the potential risk of orthosulfamuron to 

aquatic vascular plants. 

The most sensitive 96-hr EC50 value for nonvascular plants is 0.08 mg a.i./L; the associated 

NOAEC of 0.021 mg a.i./L for reductions in biomass in Skeletonema costatum is the most 

sensitive endpoint on orthosulfamuron toxicity to aquatic nonvascular plants. 

 

B.  Effects to Terrestrial Organisms

In general, available ecotoxicity data indicate that orthosulfamuron is characterized by low 

toxicity to mammals, fish, invertebrates and birds. However, the herbicide is highly toxic to 

plants. 

The acute and chronic toxicity reference values associated with orthosulfamuron exposure to 

mammals, birds, and terrestrial plants are summarized in Appendix D. 

Mammals 

An acute oral toxicity study in rats indicates that orthosulfamuron is practically non-toxic to rats 

on an acute oral exposure basis with an LD50 >5000 mg/kg-bw the highest dose tested (MRID 

46219019). 

A combined chronic/carcinogenicity study in rats was used by the Health Effects Division to 

select the dose and endpoint for establishing the chronic reference dose (for use in human 

exposure assessment). The NOAEL of 5 mg/kg/day (100 mg/kg-diet) and the LOAEL of 500 

mg/kg/day were based on changes in body weight gain, hepatotoxicity and nephrotoxicity in both 

sexes (MRID 46578913). 
26 

Birds 

Studies of acute oral (dose-based) toxicity in mallard duck (Anas platyrhynchos) and bobwhite 

quail (Colinus virginianus) indicate that orthosulfamuron is no more than slightly toxic to 

mallard duck and bobwhite quail on an acute oral exposure basis (LD50>1960 mg ai/kg-bw, 

highest dose tested). Orthosulfamuron TGAI is no more than slightly toxic to mallard duck on a 

subacute dietary exposure basis (LC50>4,790 mg ai/kg-diet, highest dose tested). 

There are no acute oral or dietary toxicity studies of orthosulfamuron formulations or 

degradates in avian species. 

No treatment-related effects on adult bird mortality, food consumption, body weight, or 

reproductive parameters and no clinical signs or treatment-related effects in offspring survival or 

body weight were observed in chronic studies of reproductive toxicity of orthosulfamuron in 

mallard duck and bobwhite quail. The NOAEC for both mallard duck and bobwhite quail is 1280 

mg a.i./kg-diet (MRID 46578949 and 46578950). 

There are no chronic toxicity studies for orthosulfamuron formulations or orthosulfamuron 

degradates in avian species. 

Terrestrial Invertebrates 

Results of available toxicity studies indicate that orthosulfamuron is practically non-toxic to 

honey bees on an acute contact and oral exposure basis. The LD50 for acute contact is >100 μg 

a.i./bee and the LD50 for acute oral toxicity is >109.4 μg a.i./bee (MRID 46219046). 

Terrestrial Plants 

Results of the Tier II seedling emergence study identify rice (Oryza sativa) as the most sensitive 

monocot and radish (Raphanus sativus) as the most sensitive dicot plants, with decreased dry 

weight as the most sensitive endpoint affected. The NOAEC and EC25 values of 0.0436 lbs 

a.i./A and 0.078 lbs a.i./A, respectively, for rice, and 0.015 lbs a.i./A and 0.040 lbs a.i./A, 

respectively, for radish is used to assess the effects of exposure to orthosulfamuron on seedling 

emergence in non-listed and listed terrestrial plants. 

Results of the Tier II vegetative vigor studies identify onion (Allium cepa) as the most sensitive 

monocot and carrot (Daucus carota) as the most sensitive dicot, with decreased dry weight as the 

most sensitive endpoint affected. The NOAEC and EC25 values of 0.00169 lbs a.i./A and 0.0048 

lbs a.i./A, respectively, for onion, and the EC25 value of 0.00012 lbs a.i./A, respectively, for 

carrot are were the most sensitive endpoints for orthosulfamuron on vegetative vigor in nonlisted and listed terrestrial plants. A definitive NOAEC for the carrot was not identified; 

therefore, quantitative risks assessment for dicots will be based on the EC05 (<0.0000664 lb 

ai/A). 

Investigations/studies have indicated that a small percentage of the label application rate of low 

dose, high-potency herbicides such as orthosulfamuron may impact the reproduction of nontarget terrestrial plants (Asghari and Evans, 1992a, 1992b; Bhatti et al., 1995; Boutin et al., 

2000; Fletcher et al., 1993; Fletcher et al., 1996a, 1996b; Pfleeger et al., 2011). However, there 
27 

are no available data on adverse reproductive impacts to terrestrial plants from orthosulfamuron 

residues due to spray drift. 

C.  Degradate Toxicity

Toxicity and risk from orthosulfamuron degradates is an area of significant uncertainty. As 

discussed in the environmental fate section (Section VI), several degradates may form via 

hydrolysis, aerobic aquatic metabolism, and anaerobic aquatic metabolism, yet there are no data 

on them. There is an exposure concern for these degradates due to the potential mobility and 

formation rates relative to the parent chemical. Acute oral rat toxicity study on DOP urea 

resulted in an LD50 of 677 mg a.i./kg-bw (male, MRID 47305223) indicating that DOP urea is 

more toxic to rats on an acute basis than parent orthosulfamuron. Degradates are discussed in 

more detail in Section XI, Stressors of Concern. 

D.  Ecological Incidents  

A preliminary review was made on July 19, 2011 of the Ecological Incident Information System 

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

Avian Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservancy. No incidents were found in the EIIS or AIMS database. 

In addition to possible incidents recorded in EIIS, additional incidents may be reported to the 

Agency in aggregated incident reports. Pesticide registrants report certain types of incidents to 

the Agency as aggregate counts of incidents occurring per product per quarter. Ecological 

incidents reported in aggregate reports include those categorized as “minor fish and wildlife” 

(W-B), “minor plant” (P-B), and “other nontarget” (ONT) incidents. “Other nontarget” incidents 

include reports of adverse effects to insects and other terrestrial invertebrates. For 

orthosulfamuron, no minor incidents were reported in the database (accessed July 19, 2011). 

In the risk assessment, these databases will be checked again and any incidents reported will be 

further evaluated to determine if the reported incidents represent current patterns of use for 

orthosulfamuron. Examples of additional considerations are mitigation (e.g., reduced application 

rates), product cancellations, and changes in use patterns that have occurred since the date of the 

reported incident(s). The absence of reported incidents should not be construed as the absence of 

incidents. Incident reports for non-target organisms typically provide information only on 

mortality events and plant damage. Sublethal effects in organisms such as abnormal behavior, 

reduced growth and/or impaired reproduction are rarely reported, except for phytotoxic effects in 

terrestrial plants. 

VIII. Evaluation of Non­definitive Toxicity Values

Many of the acute terrestrial and aquatic animal studies resulted in non-definitive toxicity values, 

meaning that the actual toxicity of the compound is “greater than” the LC50, and thus, unknown. 

This evaluation is specific to the active ingredient as the data for the TGAI may not be 

representative or predictive of toxicity for the end-use product. 
28 

Aquatic Animals 

In an effort to determine whether additional data are needed to evaluate risk to non-target aquatic 

fish and invertebrates, EFED conducted a comparison of the non-definitive toxicity value to the 

estimated aquatic concentration (EEC). The Margin of Safety (MOS) is the ratio of LOC divided 

by the RQ (see below) and represents the factor that the RQ would need to be multiplied by to 

result in a risk concern. The maximum annual application rate was used to calculate a 

conservative EEC value to compare to the toxicity data. 

• The peak EEC using the lowest Kd and the Tier I Rice Model (May 8, 2007) resulted in a 

value of 57 μg/L (See Section XI. Identification of Stressors of Concern) 

• In comparison, the lowest acute non-definitive toxicity value for aquatic animals 

(Daphnia magna) is 97.3 mg a.i./L (EC50). 

The equation shown below is used to calculate a margin of safety (MOS). 

RQ = Peak EEC/LC50

• RQ=0.0006 

• The LOC for acute exposure to listed aquatic organisms is 0.05 

MOS=LOC/RQ 

• For acute exposure to listed aquatic organisms, the MOS=83. In other words, the RQ 

would have to be 83 times higher than the current preliminary RQ to result in a risk 

concern. 

There were no mortalities or sublethal effects in the nondefinitive acute aquatic studies. There 

are no reported incidents for orthosulfamuron Therefore, the risk to aquatic organisms is 

presumed to be low and for the TGAI and additional data are not needed at this time. 

 

Birds and Mammals 

A similar exercise can be performed for birds and mammals using T-REX (v1.4.1 (US EPA, 

2008) to model orthosulfamuron residues on terrestrial plants and insects as an estimate of 

exposure to birds and mammals. The maximum application rate was used to conservatively 

estimate EECs for birds (20 g) and mammals (15 g). Using the same equations as above, the 

MOS for acute exposure to listed birds is 11 and the MOS for acute exposure to listed mammals 

is 33.11 There were no mortalities in the nondefinitive acute aquatic studies and there were no 

 

11 The peak EEC from T-REX for 20 g birds is 18.31 mg/kg-bw; the lowest acute non-definitive toxicity value for birds is 1,960 mg a.i./kg-bw 

(LD50); the equation shown below is used to calculate a MOS; RQ = Peak EEC/LD50; RQ=0.009;tThe LOC for acute exposure to listed birds is 

0.1; MOS=LOC/RQ; for acute exposure to listed birds, the MOS=11. 

The peak EEC from T-REX for 15 g mammals is 15.33 mg/kg-bw; the lowest acute non-definitive toxicity value for mammals is 5,000 mg 

a.i./kg-bw (LD50); the equation shown below is used to calculate a MOS; RQ = Peak EEC/LD50; RQ=0.003; the LOC for acute exposure to listed 

mammals is 0.1; MOS=LOC/RQ; for acute exposure to listed mammals, the MOS=33.
29 

sublethal effects. There are no reported incidents for orthosulfamuron. Therefore, the risk to 

birds and mammals is presumed to be low and additional data for the TGAI are not needed at this 

time. 

IX.  Ecosystems Potentially at Risk

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

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

However, in general terms, terrestrial ecosystems potentially at risk could include the treated 

field and immediately adjacent areas that may receive drift or runoff. Areas adjacent to the 

treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow fields or 

grasslands, woodlands, riparian habitats, and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to, or down stream from the 

treated field and might include impounded bodies such as ponds, lakes and reservoirs, or flowing 

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

marine ecosystems, including estuaries. 

X.  Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (species, community, or other entity) and its attribute or characteristics 

(USEPA, 1998). For orthosulfamuron, the ecological entities include the following: birds, 

reptiles, terrestrial-phase amphibians, mammals, freshwater fish, freshwater aquatic-phase 

amphibians and invertebrates, estuarine/marine fish and invertebrates, terrestrial plants, insects, 

aquatic plants, and algae. The attributes for each of these entities include growth, reproduction, 

and survival. 

XI.  Identification of Stressors of Concern

The identified transformation products in environmental fate studies include DBS acid, DBS 

amide, DB amine, o-desmethyl orthosulfamuron, DOP urea, DOP amine, and o-desmethyl DOP 

urea. All of these degradates may form in aerobic and anaerobic aquatic environments. 

Appendix J provides structure, identity, and fate information on the transformation products. 

Incomplete fate data are available and other degradates or higher percentages of degradates could 

be observed in metabolism studies where unidentified unextracted residues made up 33 to 43% 

of radioactivity. 

Residues of Concern for Drinking Water Consumed by Humans 

The 2007 Health Effects Division (HED) risk assessments states, “Given that HED is unable to 

conclude all these degradates are significantly less toxic than the parent, the drinking water 

assessment should be based on total residues of orthosulfamuron and its major degradates.” 

(USEPA, 2007b). The major degradates of DBS acid, DOP urea, DB amine, and o-desmethyl 
30 

orthosulfamuron are considered residues of concern in drinking water for humans.12

O-desmethyl Orthosulfamuron 

O-desmethyl orthosulfamuron was detected at 16-19% in metabolism studies. Therefore, it may 

be found in both aerobic and anaerobic environments and in soil, water, and sediment. The 

previous ecological risk assessment identified o-desmethyl orthosulfamuron as a residue of 

concern for ecological organisms and indicated that it would be assumed to have equal toxicity 

as the parent compound because it retains the parent compound’s sulfamoylurea structural group 

(USEPA, 2006, D333514), see Figure 3. As this degradate is a sulfonylurea, a total toxic 

residue (TTR) approach is used for evaluating risk for all taxa from exposure to the O-desmethyl 

degradate. 

Orthosulfamuron O-desmethyl orthosulfamuron 

Figure 3. Structures of Orthosulfamuron and O-desmethyl orthosulfamuron 

DOP Urea and O-desmethyl DOP urea 

DOP urea and o-desmethyl DOP urea are substituted ureas. Ureas are a common class of 

herbicides used on a large number of agricultural crops. The DOP urea is a precursor to odesmethyl DOP urea (see Figure 4) and was observed at up to 78% of applied radioactivity in 

the hydrolysis study (pH 4 at 50o

C), 47% of applied radioactivity in the aerobic aquatic 

metabolism study, and 19% of applied radioactivity in the anaerobic aquatic study. This indicates 

that exposure to aquatic and terrestrial organisms is possible as DOP urea will likely be present 

in paddy water and sediment in the rice paddy and may form on food residues or in soil. 

Additionally, DOP urea was detected in soil and sediment in the aquatic field dissipation study 

and estimated dissipation half-lives ranged from 30 to 37 days in sediment to 177 to 330 days in 

soil.13 The absence of detections in water in the aquatic field dissipation study may be related to 

the high limit of quantitation (LOQ) of 5 μg/L14, use of poor analytical methods15, the low 

 

12 HED did not consider DOP amine and DBS amide as major degradates because they were only observed as major 

degradates in hydrolysis studies at 50o

C (Personal Communication with Richard Loranger, Christine Olinger, Karlyn 

Middleton, and Christina Swartz 08/17/2011). 

13 Half-lives for degradates were calculated using the time point beginning with the highest concentration of DOP 

urea measured in the identified media to the final sampling interval where the degradate was observed and using the 

single first order degradation equation. Linear regression was used to fit the single first order model by taking the 

natural log of concentrations measured at each time point. Simultaneous formation and decline of DOP urea was not 

considered in the calculation and thus the estimated rate of degradation is likely slower than the actual value. 14 This LOQ is higher than some of the aquatic life benchmarks available for ureas. 

N

O

NH

S

O

O

NH

O

NH

N

N

O

O

N

NH S NH NH N

N

OH

O

O O

O

O
31 

application rate (33.7% of the theoretical amount), and/or the frequency of sampling. While odesmethyl DOP urea was identified as a minor degradate, the only difference in structure 

between DOP urea and o-desmethyl DOP urea is a methyl group and the toxicity of these 

compounds was assumed to be similar. An analysis of available aquatic toxicity data on ureas 

with a similar structure to these degradates is presented in Appendix B. Vascular plant data 

indicate that orthosulfamuron is more toxic than ureas; however, ureas were an order of 

magnitude higher in toxicity than orthosulfamuron for nonvascular plants. Additionally, 

orthosulfamuron concentrations in paddy water were estimated to determine whether 

concentrations in water could be high enough to result in a risk concern (see Appendix F). A 

preliminary estimate of peak orthosulfamuron EECs using the lowest Kd and the Tier I Rice 

Model resulted in a value of 57 μg/L. Concentrations of urea residues for maximum amounts of 

DOP urea, o-desmethyl DOP urea, and unextracted residues were estimated to range from 10 to 

15 μg/L (Appendix F). Measured nonvascular plant Aquatic Life Benchmarks for ureas range 

from 2.4 to 80 μg/L. This indicates that total urea concentrations have the potential to be present 

at high enough to cause a risk concern for non-vascular aquatic plants. Therefore, data will be 

requested on DOP urea for nonvascular aquatic plants. Finally, acute and chronic Aquatic Life 

Benchmarks (ALB)16 for some ureas are much lower than those for orthosulfamuron. Acute 

ALB of three ureas (diuron, fluometuron, and linuron) are much lower than the benchmark for 

orthosulfamuron. The lower urea acute ALBs for fish were 200, 320, and 1500 μg/L and acute 

ALBs for invertebrates were 60, 80, and 110 μg/L. Acute ALBs for ureas indicate there is a 

small chance that a risk concern (for endangered species only) could result for invertebrates 

(ALB/LOC = 60/0.5 = Toxicity endpoint of 120 μg/L; EEC/Toxicity Endpoint=15/120 = 0.13).17 

Chronic ALBs for ureas (range from 0.09 to 21,800 μg/L) are much lower than those for 

orthosulfuramuron (range from 6,100 to 6,500 μg/L) and some are lower than the urea EECs of 

10 to 15 μg/L; therefore, acute data for aquatic invertebrates and chronic data for fish and 

invertebrates on DOP urea are also needed.18 Without data for DOP urea, risk estimates will be 

calculated using available data for urea herbicides. To estimate exposure to the ureas for aquatic 

organisms, an EEC will be estimated considering exposure to both DOP urea and o-desmethyl 

DOP urea and the EEC will be compared to effects data for DOP urea. 

 15 The ECMs may be adequate for successful ILV validation; however, the quality is currently unknown as the ILVs 

were conducted on ECMs that were not used in the study. Additionally, the LOQ was 0.02 mg/L (20 μg/L) for 

orthosulfamuron. This is higher than the LOQ needed as the lowest toxicity endpoint multiplied by the LOC is 0.2 

μg/L. Finally, the not all major degradates were looked for in the study. 

16 Benchmarks, developed for baseline risk assessments, are estimates of the concentrations below which pesticides 

are not expected to harm aquatic life. Each Aquatic Life Benchmark is based on the most sensitive, scientifically 

acceptable toxicity endpoint available to EPA for a given taxon (for example, freshwater fish) of all scientifically 

acceptable toxicity data available to EPA multiplied by the corresponding level of concern of 0.5 for acute endpoints 

and 1.0 for chronic and plant endpoints. Aquatic life benchmarks may be found at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm. 17 See Appendix B for a summary of the species each ALB is based on. 

18 Three of six chronic values ranged from 0.09 – 26 μg/L and were in the range of EECs estimated for ureas of 10 

to 15 μg/L. 
32 

DOP Urea O-desmethyl DOP urea 

Figure 4. Structures of DOP urea and O-desmethyl DOP urea 

While EFED has uncertainty about the potential toxicity of the DOP urea degradate to terrestrial 

plants, a simple comparison of tier II plant toxicity data for other phenyl urea herbicides (diuron, 

linuron, tebuthiuron and fluometron) indicate that the parent, orthosulfamuron, is likely more 

toxic or has similar toxicity to terrestrial plants than the DOP urea degradate (assuming that the 

DOP urea degradate is of equal toxicity to the phenyl urea herbicides). Therefore, tier II 

terrestrial plant toxicity data are not required for DOP urea or o-desmethyl DOP urea at this time. 

Terrestrial plant data for urea herbicides are summarized in Appendix B. 

Data for DOP urea indicate that it is more toxic to mammals on an acute basis than the parent 

(acute oral LD50 = 677 mg/kg-bw for DOP urea as compared to >5000 mg/kg-bw for 

orthosulfamuron). Additionally, T-REX version 1.4.1 was used to determine whether potential 

exposure to the ureas could be high enough to result in a risk concern (Appendix L). While the 

ratios of EEC to the acute oral LD50 for DOP urea (RQ=0.0029) was higher than the ratio of the 

EEC to the highest level tested in the acute oral study for orthosulfamuron (highest EEC/nondefinitive endpoint ratio < 0.0014), exposure was not high enough to result in a risk concern. 

Data are not available to evaluate and compare chronic risk from exposure to DOP urea and odesmethyl DOP urea to parent orthosulfamuron. The chronic NOAEC for linuron (12.5 mg/kgdiet), a phenyl urea, was used to estimate whether it was likely that chronic toxicity to mammals 

could result from exposure to DOP urea and o-desmethyl DOP urea. A preliminary estimate of 

risk indicated that exposure was high enough to result in a risk concern (Appendix L) and risk 

due to exposure to DOP urea and o-desmestheyl DOP urea could be higher than risk due to 

exposure to orthosulfamuron (linuron endpoint/highest chronic EEC from T-REX = 2.69 versus 

highest RQ for orthosulfamuron of 1.4). Based on acute data on birds, linuron is one of the more 

toxic herbicides of the phenyl urea class and toxicity of DOP urea may be overestimated using 

the linuron endpoint. Additionally, if a more realistic high estimate of the formation of DOP 

urea (47% based on the maximum radioactivity observed as DOP urea in the aerobic aquatic 

metabolism study) the estimated RQ drops to 1.54. This is in the range of RQs estimated for the 

parent. Additional mammalian toxicity data on DOP urea and o-desmethyl DOP urea are not 

needed at this time; however, potential for acute and chronic risk to terrestrial mammals due to 

exposure to the urea degradates will be evaluated in the risk assessment based on available data, 

including data on urea herbicides. If additional uses are proposed resulting in increased 

exposure, data for DOP urea and o-desmethyl DOP urea may be needed for mammals. 

Data are not available on DOP urea or o-desmethyl DOP urea for birds or terrestrial 

invertebrates. Data on urea herbicides were compared to the toxicity endpoints for 

orthosulfamuron to determine whether it was likely that these degradates would be more toxic 

N2 H NH N

N

O

O

O

N

H

O

H2N

N

N O

OH
33 

than orthosulfamuron. Forty-eight hour LD50 values for the urea herbicides diuron, tebuthiuron, 

linuron, and monuron ranged from 100 to >145 μg/bee. The 48-hr hour LD50 values for 

orthosulfamuron were >100 and >109.4 μg/bee. Therefore, ureas are not expected to be more 

toxic to terrestrial invertebrates than parent orthosulfamuron. Twenty-nine avian 4-16 day LC50

values were available for ureas and values for linuron, diuron, tebuthiuron, fluometuron, and 

monuron and are lower (1700 to 4682 mg/kg-diet) than those for orthosulfamuron (>4790 and 

>4980 mg/kg-diet). The only definitive 14-day LD50 value was higher than the highest level 

tested for orthosulfamuron. All chronic reproduction avian endpoints were lower for ureas 

(range: 42.8 to 100 mg/kg-diet) than for orthosulfamuron (1280 mg/kg-diet). Therefore, it is 

possible that the acute and chronic toxicity of DOP urea and o-desmethyl DOP urea is greater 

than the toxicity of orthosulfamuron. T-REX version 1.4.1 was used to determine whether 

potential exposure to the ureas could be high enough to result in a risk concern (Appendix L). 

While the ratios of EEC to the lowest urea endpoints available for birds (<0.01 to 0.05) was 

higher than the risk estimated for orthosulfamuron (<0.01 to 0.01), exposure was not high 

enough to result in a risk concern for birds. Acute and chronic risk to birds will be evaluated in 

the risk assessment using available data. If new uses are proposed resulting in increased 

exposure, data on the toxicity of DOP urea may be needed for birds. 

DBS acid, DOP amine, DBS amide, and DB amine 

DBS acid and DOP amine were observed at greater than 50% applied radioactivity (each 

individually) in fate studies. DB amine and DBS amide were detected at maximums of 1-13% in 

hydrolysis studies conducted at 25 and 50oC and 1-4% in metabolism studies. Figure 5 shows 

the structures of these degradates. ECOSAR version 1.0 was used to estimate the toxicity of 

these degradates as no data were available to evaluate their toxicity (Table 6). ECOSAR is only 

used to prioritize the need for additional data on degradates. Data on the aniline and amide 

chemical classes were used to estimate toxicity endpoints (see the description of data in the Help 

section of ECOSAR). Very limited data sets were available to develop the regressions for the 

compounds and there is much uncertainty in these estimated values; however, this is one of the 

best methods available to estimate ecological toxicity. DOP amine and DB amine were both 

identified to be potentially more toxic to aquatic animals than parent orthosulfamuron on a 

chronic exposure basis. They are also major degradates and are likely to be present in the 

aquatic environment. DOP amine was a major degradate observed in the hydrolysis study at a 

maximum of 53% at pH (11% at pH 7 at 50o

C) with maximums observed at the final sampling 

interval indicating higher levels may have been observed if the study was conducted for a longer 

time frame. DB amine was observed at a maximum of 13% in the hydrolysis study at pH 9 (2% 

at pH 7 and 25o

C and 11% at pH 7 50oC) with maximums observed at the final sampling interval 

indicating that higher percentages may have been observed in a longer study. DB amine and 

DOP amine were not looked for in the aquatic field dissipation study. EECs were estimated for 

DOP amine and DB amine using the molecular weight and maximum amounts observed in the 

aerobic aquatic metabolism study. EECs were estimated assuming maximum amounts of 1% 

and 34% (e.g., assuming unextracted residues were the parent) for both DB amine and DOP 

amine. EECs ranged from 0.2 to 7 μg/L for DB amine and 0.3 to 9 μg/L for DOP amine and 

were at least 10x lower than the lowest estimated toxicity endpoints (50 to 949 μg/L). Estimated 

risk due to exposure to DOP amine and DB amine is higher than risk due to exposure to 

orthosulfamuron; however, exposure would need to be 6 to 187 times higher for DOP amine and 
34 

10 to 358 times higher for DB amine to result in a risk concern and the exposure estimate is 

already very conservative due to the assumption that unextracted residues were the degradate of 

interest. Therefore, data on these degradates is not needed at this time; however, if exposure 

estimates for these degradates increases, data may be needed for future risk assessment and these 

may be considered residues of concern. 

DBS Acid DOP Amine 

DBS Amide DB Amine 

Figure 5. Structures of DBS Acid, DOP Amine, DBS Amide and DB Amine 

Table 6. Comparison of Measured Toxicity Endpoints for Orthosulfamuron with 

Estimated Aquatic Toxicity Endpoints for DBS Acid, DBS amide, DB amine, and DOP 

amine (estimated using ECOSAR versioin 1).* 

Compound 

(compounds class 

used by ECOSAR) 

Estimated Toxicity Endpoint (mg/L) 

96-hr FW fish 

EC50/LC50

48-hr 

Daphnid 

LC50

96-hr EC50

Green Algae 

Fish Chronic 

Value 

Daphnid 

Chronic 

Value 

Orthosulfamuron 

(measured) 

>122 

>142 

>97.3 

>129 

6.2 6.1 6.5 

DBS acid (amide) 5.32+005 47315.2 16.6 3147.7 624.2 

DBS amide (amide) 3754.3 852.5 2.9 22.2 11.3 

DB amine (aniline, 

amide) 

155.8 3.2 1.0 0.9 0.08 

DOP amine (aniline) 78.9 2.4 9.2 0.4 0.05 

*All toxicity endpoints were estimated using ECOSOAR version 1.0 except data in the first row for 

orthosulfamuron. When a chemical was in multiple chemical classes the lowest endpoint from all estimates is 

shown. Bold values indicate that the endpoint was much lower than that measured for the parent. These toxicity 

N

NH S

O

O

O

OH

N2 H N

N

O

O

N

NH S NH2

O

O

O

N

NH2

O
35 

estimates are only used to prioritize which degradates are likely a risk concern and how they should be handled in 

the risk assessment. The estimated values may over or under estimate actual toxicity of the compounds. Appendix 

C provides the output from ECOSAR. 

 

Method of Estimating Exposure and Evaluating Risk for Degradates 

To estimate exposure to compounds assumed to have a similar toxicity to the parent (e.g., odesmethyl orthosulfamuron for aquatic organisms and parent, DBS acid, DOP urea, DB amine, 

and o-desmethyl orthosulfamuron for human drinking water exposure estimates), a total toxic 

residue (TTR) approach will be used by summing the residues observed in fate studies and then 

estimating degradation rates based on the total summed residues. The TTR degradation rates 

will then be used to estimate exposure in place of degradation rates for the parent alone. Data on 

organic-carbon normalized distribution coefficients is requested for degradates observed in high 

percentages in the fate studies (DBS acid19 and DOP urea) and the lowest estimated KOC will be 

used in modeling. The modeled total toxic residue amounts will then be compared to toxicity 

endpoints for the parent. This approach is called the Total Toxic Residue (TTR) approach. As 

discussed previously, EECs will be estimated for DOP urea and o-desmethyl DOP urea 

combined residues and compared to toxicity endpoints for DOP urea or data from the urea 

herbicides. Available data are not adequate to estimate half-lives in an aerobic aquatic system 

for the ureas; therefore, stability will be assumed unless more data are available to characterize 

this uncertainty. The application rate of the parent will be converted to a urea equivalents 

application rate using molecular weight and the highest percentages of the ureas observed in fate 

studies. The estimated application rate along with available fate will be used in models to 

estimate an exposure concentration for the ureas. Table 7 summarizes the different approaches 

for assessing risk to degradates for each taxa. 

Table 7. Summary of residues of concern for different classes of organisms. 

Transformation 

Product 

Is the transformation product a residue of concern? 

If yes, what approach will be used to evaluate potential risk due to exposure to degradate 

Aquatic 

Animals 

Aquatic 

Plants 

Terrestrial 

Vertebrates 

Terrestrial 

Invertebrates 

Terrestrial Plants 

o-desmethyl 

orthosulfamuron 

Yes-TTR1 Yes-TTR1 Yes-TTR2 Yes-TTR1

DBS acid No No No 

DB amine No, at current 

exposure 

levels 

No No 

DBS amide No No No No No 

DOP amine No, at current 

exposure 

levels 

No No No No 

DOP urea Yes – EECs estimated for 

ureas and compared to 

toxicity endpoint for DOP 

urea or urea herbicides 

Yes – EECs 

estimated for ureas 

and compared to 

toxicity endpoint 

for DOP urea or 

urea herbicides 

No No 

o-desmethyl 

DOP urea 

 

19 DBS acid is a residue of concern for human healt drinking water assessments; therefore, this KOC would only be 

used in the human health drinking water assessment. 
36 

Abbreviation: TTR= Total toxic residue approach 

1

 Residues included in the TTR approach for these taxa are the parent and o-desmethyl orthosulfamuron. 

2

 Residues included in the TTR approach for these taxa are the parent, DBS acid, and DB amine based on HED 

analysis of residues of concern for humans. As these degradates are assumed to have similar toxicity to the parent 

and exposure estimates are not related to the fate data, the presence of these degradates does not alter the estimate of 

risk for these taxa from that estimated for the parent alone. If one of these degradates is found to be more toxic than 

the parent or if the presence of these degradates could influence the estimate of exposure, this approach will be 

revisited. 

For terrestrial vertebrates, the residues of concern include the parent, DBS acid, DOP urea, DB 

amine, and o-desmethyl orthosulfamuron as these were the residues of concern identified for 

human health (USEPA, 2007b). While the TTR approach was the approach identified as the 

method to evaluate risk due to exposure to orthosulfamuron and major degradates other than the 

ureas for terrestrial vertebrate and invertebrates, fate data are not used in T-REX (unless foliar 

dissipation data are available20), the model used to estimate terrestrial exposure. Therefore, even 

though a TTR approach was identified for terrestrial animals the exposure estimates will not 

change. If this changes in the future, a more complete analysis of the residues of concern for 

terrestrial animals will be made. 

Mixtures 

Evaluation of pesticide environmental mixtures is beyond the scope of this assessment because 

of the myriad factors that cannot be quantified based on the available data. Those factors include 

identification of other possible co-contaminants and their concentrations, differences in the 

pattern and duration of exposure among contaminants, and the differential effects of other 

physical/chemical characteristics of the receiving waters (e.g. organic matter present in sediment 

and suspended water). Evaluation of factors that could influence additivity/synergism is beyond 

the scope of this assessment and the capabilities of the available data to allow for an evaluation. 

However, it is acknowledged that not considering mixtures could over- or under-estimate risks 

depending on the type of interaction and factors discussed above. The assessment will, however, 

analyze the toxicity of formulated products (including formulations involving more than one 

active ingredient) and will determine whether formulated products are more toxic than the 

technical grade active ingredient data used for assessing both direct and indirect risks. One 

registered product contains a co-pack of two separate herbicides, one contains 50% 

orthosulfamuron and the other 75% quinclorac, a quinolinecarboxylic acid herbicide. The 

products are mixed and applied rice.

XII. Conceptual Model

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

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

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure. 

 

20 Foliar dissipation data are not available for orthosulfamuron. 
37 

The conceptual model for orthosulfamuron provides a written description and visual 

representation of the predicted relationships between orthosulfamuron and degradates, potential 

routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model 

consists of two major components: risk hypothesis and a conceptual diagram (USEPA, 1998). 

As discussed previously, one ecological risk assessment has been conducted by EFED for 

orthosulfamuron (USEPA, 2006, D333514). Potential for direct effects to aquatic vascular 

plants, non-vascular plants, and terrestrial plants were identified. Additionally, indirect effects to 

taxa that rely on plants for habitat and food could be indirectly affected. 

A.  Risk Hypothesis

A risk hypothesis describes the predicted relationship among the stressor, exposure, and 

assessment endpoint response along with the rationale for their selection. For orthosulfamuron, 

the following ecological risk hypothesis is being employed for this national-level ecological risk 

assessment: 

Given the uses of orthosulfamuron and its environmental fate properties, there is a 

likelihood of exposure to non-target terrestrial and/or aquatic organisms. When used in 

accordance with the label, orthosulfamuron and its degradates may result in adverse 

effects upon the survival, growth, and reproduction of non-target terrestrial and/or aquatic 

organisms. These nontarget organisms may include Federally-listed threatened and 

endangered species. Based on the previous risk assessment and analysis supporting this 

problem formulation, direct effects are likely for mammals and for aquatic and terrestrial 

plants and indirect effects may result for all other taxa due to direct effects on plants. As 

some degradate toxicity data are not available and were not evaluated in the previous 

assessment, it is uncertain whether direct effects are likely to occur for aquatic organisms. 

B.  Conceptual Diagram

The conceptual model depicts the potential pathways for ecological risk associated with 

orthosulfamuron use on rice. The conceptual model provides an overview of the expected 

exposure routes for terrestrial and aquatic organisms. 

The potential exposure pathways and effects of orthosulfamuron on aquatic environments are 

depicted in Figure 6 and for terrestrial environments in Figure 7. Figure 8 depicts exposure 

from drinking water and inhalation to terrestrial vertebrates and invertebrates. Stressors of 

concern for aquatic animals include parent, o-desmethyl orthosulfamuron, DOP urea, and odesmethyl DOP urea. Stressors of concern for terrestrial animals include orthosulfamuron, odesmethyl orthosulfamuron, DBS acid, DB amine, DOP urea, and o-desmethyl DOP urea. The 

stressors of concern for aquatic plants include parent orthosulfamuron and o-desmethyl 

orthosulfamuron, DOP urea, and o-desmethyl DOP urea. The stressors of concern for terrestrial 

plants are orthosulfamuron and o-desmethyl orthosulfamuron. Solid arrows depict the most 

likely routes of exposure and effects; dashed lines depict potential routes of exposure that are not 

considered likely for orthosulfamuron. Orthosulfamuron will enter the environment via direct 
38 

application to water and terrestrial environments when it is applied for dry-seeded rice. It may 

move off site via spray drift, runoff, leaching, volatilization, release of paddy water, and use of 

paddy water as irrigation water. While orthosulfamuron’s vapor pressure indicates it is 

semivolatile, it is not expected to volatize from water or moist soil (see discussion in Section 

IVC). Additionally, the Screening Tool for Inhalation Risk (STIR) version 1.0 (November 23, 

2010) indicates that exposure via inhalation is not likely to be a risk concern for birds and 

mammals (Appendix E). These results combined with the estimated atmospheric half-life of 

less than two days indicate that long range transport in the vapor phase is not an exposure 

pathway of concern. Additionally, the KOA, KOW, and BCF indicate that orthosulfamuron is not 

likely to bioconcentrate or bioaccumulate in aquatic or terrestrial organisms. Organic-carbon 

normalized distribution coefficients (KOC) values range from 217 to 2,330 L/kg-OC indicating that 

orthosulfamuron has the potential to leach into groundwater and will be present at significant 

concentrations in some sediments; however, toxicity endpoints for aquatic invertebrates indicate 

that this exposure is not likely to be a risk concern. The Screening Imbibition Program (SIP) 

version 1.0, August 19, 2010 indicates that orthosulfamuron has the potential to be present in 

drinking water (pH 7.0 and 8.5) at high enough concentrations to result in a risk concern 

(Appendix E). This is a highly conservative evaluation as SIP assumes that concentrations in 

drinking water could be at the level of solubility. Additionally, non-definitive acute endpoints 

for mammals and birds and definitive chronic endpoints were used in the model. Finally, surface 

and shallow ground water contaminated with orthosulfamuron has the potential to be used as 

irrigation water and may result in exposure to terrestrial plants (Appendix J). Although 

orthosulfamuron may be applied as a granule or as a flowable, spray drift is only expected to 

result in significant exposure with broadcast applications (both aerial and ground spray) of the 

flowable formulations. Dry formulations that are applied as a flowable may result in significant 

spray drift exposure. As discussed previously, there are potential reproductive effects to plants.
39 

*Spray drift is not expected to be a significant pathway of exposure for applications of granular materials.

Figure 6. Conceptual model depicting stressors, exposure pathways, and potential effects 

to aquatic organisms from the use of orthosulfamuron to rice. 
40 

*Spray drift is not expected to be a significant pathway of exposure for applications of granular materials. See 

Figure 4 for drinking water and inhalation exposure pathways for terrestrial vertebrates and ingestion of residues in 

dew by terrestrial invetebrates. 

Figure 7. Conceptual model depicting stressors, generic exposure pathways, and potential 

effects to terrestrial organisms (terrestrial plants, terrestrial invertebrates, and dietary 

routes of exposure for terrestrial vertebrates) from the use of orthosulfamuron on rice. 
41 

*Spray drift is not expected to be a significant pathway of exposure for applications of granular materials.

Figure 8. Conceptual model depicting stressors, drinking water and inhalation exposure 

pathways, and potential effects to terrestrial animals from the use of orthosulfamuron on 

rice. 

XIII. Analysis Plan  

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

estimated. The use, environmental fate, and ecological effects of orthosulfamuron are 

characterized and integrated to assess the risks. This is accomplished using a risk quotient (ratio 

of exposure concentration to effects concentration) approach. Although risk is often defined as 

the likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does 

not provide a quantitative estimate of likelihood and/or magnitude of an adverse effect. 

However, as outlined in the Overview Document (USEPA, 2004), the likelihood of effects to 

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

value. 
42 

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

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

orthosulfamuron. 

A. Measures of Exposure  

In order to estimate risks of orthosulfamuron exposures in aquatic and terrestrial environments, 

all exposure modeling and resulting risk conclusions will be based on maximum application rates 

and methods cited in Table 1 and will be estimated for each use of orthosulfamuron. Measures 

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

concentrations (EECs) of orthosulfamuron. 

1. Exposure to Aquatic Organisms in the Rice Paddy 

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

direct water use with conservative, maximum values that represent high exposure sites for rice 

use. Each of these sites represents 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.21 The 

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

The model does not account for pesticide degradation, mass transfer between the aqueous phase 

and the sediment, volatilization, dilution, or other dissipation processes. The sediment 

interaction depth was determined by calibrating the model to maximum residues measured in 

paddy water in dissipation studies. Pesticide degradation, mass transfer, volatilization, dilution 

and other dissipation processes may have occurred in those datasets but data were calibrated to 

the maximum measured residues which would reduce the influence of these processes. The 

model was not evaluated or calibrated for concentrations measured in sediment and does not 

estimate a sediment concentration. Guidance for using the Tier I Rice Model may be found on 

the U.S. Environmental Protection Agency (EPA) Water Models web-page (USEPA, 2007b). 

 

21 Orthosulfamuron Kd values range from 2.5 to 20.7 L/kg and KOC values range from 215 to 2145 L/kg-OC (MRID 

46578971). 
43 

Refinements may be made to EFED’s Tier I Rice Model to incorporate aerobic soil and aerobic 

aquatic degradation into the equations discussed above to arrive at acute and chronic 

concentrations and to estimate a concentration in water after a specified holding period. The 

following equation may be used to estimate the concentration in paddy water as a function of 

time: 

Cw, t = Cw, 0 e(-kt) 

Where 

Cw, t = the concentration in water at time, t 

Cw, 0 = the concentration in water at application or time of zero (calculated using the Tier I 

 Rice Model) 

e = base of natural logarithm 

k = first-order rate constant (1/days) 

t = time after application (days) 

When two applications are modeled, the initial concentration in the water after each application 

is estimated using the Tier I Rice model, degradation/dissipation is modeled from the date of 

application for every day after for a specified time. Concentrations in water from the first and 

second applications are added to determine the total concentration in water over time for each 

day. Acute concentrations are reported at the maximum concentration for the given scenario. 

Chronic concentrations are taken as the average daily concentration with days from the first 

application to the number of days specified for paddy water. An estimate of exposure for tail 

water is made if paddy water is required to be held for a number of days after application and 

represents the concentration in water when paddy water is released. 

2. Exposure to Terrestrial Animals via Residues on Food Items 

Exposure estimates for terrestrial animals assumed to be in the target area or in an area exposed 

to spray drift are derived using the T-REX model (version 1.4.1, 10/09/2008). This model 

incorporates the Kenaga nomograph, as modified by Fletcher et al. (1994), which is based on a 

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

bound of residue values from actual field measurements (Hoerger and Kenaga, 1972). The 

Fletcher et al. (1994) modifications to the Kenaga nomograph are based on measured field 

residues from 249 published research papers, including information on 118 species of plants, 121 

pesticides, and 17 chemical classes (Fletcher et al., 1994). 

3. Exposure to Terrestrial Animals via Drinking Water 

Based on results from SIP, exposure to birds and mammals via exposure in drinking could result 

in a risk concern. Therefore, EECs will also be estimated for terrestrial organisms that may 

consume dew, or puddles. Methods of estimating exposure via these pathways are currently 

under development. If EECs for dew and puddles are lower than those for use of paddy water as 

a drinking water source, than risk due to consumption of paddy water will be evaluated using 

body weight-specific consumption rates and the concentration of orthosulfamuron residues in 
44 

water bodies (USEPA, 1993, 1998, 2008a). 

4. Exposure to Terrestrial Plants from Spray Drift 

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

1.2.2, 12/26/2006). This model uses estimates of pesticides in runoff and in spray drift to 

calculate EECs. EECs are based upon solubility, application rate and minimum incorporation 

depth. For rice uses, only exposure to spray drift is assessed. AgDRIFT may also be used to 

assess exposure to spray drift. 

5. Exposure to Terrestrial Plants from Residues in Irrigation Water 

Non-target crops may be exposed to contaminated irrigation waters from surface water or 

shallow ground water containing orthosulfamuron. The potential risks to plants when exposed to 

irrigation water contaminated with orthosulfamuron will be estimated for both ground water and 

surface water irrigation sources. The EEC for ground water will be calculated using the Tier 1 

SCIGROW model while that for surface water will be calculated using the Tier I Rice Model 

from the scenario yielding the highest EECs. Comparisons will be made to the most sensitive 

endpoint from the vegetative vigor study assuming that runoff of irrigation water does not occur. 

6. Exposure to Aquatic Organisms based on Monitoring Data 

Available monitoring data will be used to qualitatively characterize exposure and compare with 

modeling results. The Agency is aware of monitoring conducted by Federal and state agencies 

and this route of exposure will be considered in the assessment to the extent that data on 

orthosulfamuron are available. 

7. Exposure to Spray Drift 

Two spray drift models, AgDisp and AgDRIFT, are used to assess exposures of aquatic and 

terrestrial organisms to orthosulfamuron deposited in terrestrial and aquatic habitats by spray 

drift. AgDrift (version 2.01; dated 5/24/2001) is the model most commonly used to simulate 

spray drift into terrestrial and aquatic environments. AgDisp (version 8.13; dated 12/14/2004) 

(Teske and Curbishley, 2003) is used when a parameter needs to be modeled that is not available 

in AgDRIFT. Spray drift analysis will be an important part of the analysis in defining the 

potential area of effects for endangered species. 

B. Measures of Effect

Ecological effect data are used as measures of direct and indirect effects to biological receptors. 

Data are obtained from registrant-submitted studies or from literature studies identified by 

ECOTOX. The ECOTOXicology database (ECOTOX) will be searched in order to provide more 

ecological effects data to bridge existing data gaps. ECOTOX is a source for locating single 

chemical toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial 

plants, and wildlife. ECOTOX was created and is maintained by the USEPA, Office of Research 
45 

and Development, and the National Health and Environmental Effects Research Laboratory's 

Mid-Continent Ecology Division (USEPA, 2009a). 

Information on the potential effects of orthosulfamuron on non-target animals is also collected 

from the Ecological Incident Information System (EIIS) (USEPA, 2007a). The EIIS is a 

database containing adverse effect (typically mortality) reports on non-target organisms where 

such effects have been associated with the use of pesticides. 

Where available, sublethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects have included behavioral changes (e.g., 

lethargy, changes in coloration and effects olfaction). Quantitative assessments of risks, though, 

are limited to those endpoints that can be directly linked to the Agency’s assessment endpoints of 

impaired survival, growth and reproduction. 

The assessment of risk for direct effects to non-target organisms makes the assumption that 

toxicity of orthosulfamuron to birds is similar to terrestrial-phase amphibians and reptiles. The 

same assumption is made for fish and aquatic-phase amphibians. 

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

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

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

Concentration” and LC50 is the concentration of a chemical that is estimated to kill 50% of the 

test organisms. EC stands for “Effective Concentration” and the EC50 is the concentration of a 

chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints 

for chronic measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and 

NOEC. NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest tested 

dose of a substance that has been reported to have no harmful (adverse) effects on test 

organisms. The NOAEC (i.e., “No-Observed-Adverse-Effect-Concentration”) is the highest test 

concentration at which none of the observed effects were statistically different from the control. 

The NOEC is the No-Observed-Effects-Concentration. For non-listed plants, only acute 

exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed 

plants, either the NOAEC or EC05 is used. 

C. Integration of Exposure and Effects

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

determine the potential ecological risk from the use of orthosulfamuron on rice, and the 

likelihood of direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. 

The exposure and toxicity effects data are integrated in order to evaluate the risks of adverse 

ecological effects on non-target species. For the assessment of orthosulfamuron risks, the risk 

quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are 

divided by acute and chronic toxicity values. The resulting RQs are then compared to the 

Agency’s LOCs (USEPA, 2004). These criteria are used to indicate when orthosulfamuron’s 

uses, as directed on the label, have the potential to cause adverse direct or indirect effects to nontarget organisms. As noted previously, where data are lacking on the toxicity of 

orthosulfamuron, risk will be presumed. 
46 

 

1. Deterministic and Probabilistic Assessment Methods 

The quantitative assessment of risk will primarily depend on the deterministic point-estimate 

based approach described in the risk assessment. An effort may be made to further describe risk 

using probabilistic tools that the Agency has developed. These tools have been reviewed by 

FIFRA Scientific Advisory Panels and have been deemed as appropriate means of refining 

assessments where deterministic approaches have identified risks. 

D. Endangered Species Assessments

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

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

registered uses of orthosulfamuron. This assessment will be conducted in accordance with the 

Overview Document (USEPA, 2004), provisions of the ESA, and the Services’ Endangered 

Species Consultation Handbook (USFWS/NMFS, 1998). 

The action area is used to identify all listed (threatened and endangered) species and designated 

critical habitat that could be affected by the Federal action. The Federal action is the 

authorization or registration of pesticide use or uses as described on the label(s) of pesticide 

products containing a particular active ingredient. The action area is defined by the Endangered 

Species Act as, “all areas to be affected directly or indirectly by the Federal action and not 

merely the immediate are involved in the action” (50 CFR §402.2). Based on an analysis of the 

Federal action, the action area is defined by the actual and potential use of the pesticide. 

In the case of nationwide ecological risk assessment conducted for orthosulfamuron under 

Registration Review, the action area will encompass the entire United States and its territories. 

The purpose of defining the action area as the entire United States and its territories is to ensure 

that the initial area of consideration encompasses all areas where orthosulfamuron may be used 

now and in the future, including the potential for off-site transport via spray drift and 

downstream dilution. Additionally, the concept of a nationwide action area takes into account 

the potential for direct and indirect effects and any potential modification to critical habitat based 

on ecological effect measures associated with reduction in survival, growth, and reproduction, as 

well as the full suite of sublethal effects available in the effects literature. It is important to note 

that the nationwide action area does not imply that direct and/or indirect effects and critical 

habitat modification are expected to or are likely to occur over the full extent of the action area, 

but rather to identify all listed species and critical habitat that may potentially be affected by the 

action. The Agency will use more rigorous analysis including consideration of available land 

cover data, toxicity data, and exposure information to determine areas where individual listed 

species and designated critical habitat may be affected or modified via endpoints associated with 

reduced survival, growth, or reproduction. 

E.  Human Health Drinking Water Assessment

In order to bring the drinking water assessment up to date with current data, models and 

simulation model guidance, a new drinking water assessment will be conducted to support future 
47 

human health dietary risk assessments of orthosulfamuron. The drinking water assessment will 

incorporate model estimates of orthosulfamuron and its major degradates (using a TTR 

approach) in surface water and groundwater. Concentrations of orthosulfamuron and major 

degradates in surface waters will be estimated using the Tier I Rice Model (see description 

above). 

An Estimated Drinking Water Concentration (EDWC) of orthosulfamuron and its major 

degradates in groundwater will be estimated using EFED’s Tier I aquatic model SCIGROW 

(Screening Concentration in Ground Water, version 2.3; 8/8/2003). SCIGROW is a regression 

model used as a screening tool to estimate pesticide concentrations found in ground water used 

as drinking water. The output of SCIGROW represents the concentrations that might be 

expected in shallow unconfined aquifers under sandy soils, which is representative of the ground 

water most vulnerable to pesticide contamination likely to serve as a drinking water source. 

The drinking water assessment will also include available surface and ground water monitoring 

data with consideration of changes in use patterns that may have occurred. States are encouraged 

to submit monitoring data for review. 

F. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its reregistration decision, EPA reviewed these data and selected 

the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard 

database. However, as required by FFDCA section 408(p), orthosulfamuron is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

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

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

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

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

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

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

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

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

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

establish a dose-response relationship between the dose and the E, A, or T effect. 
48 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

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

Orthosulfamuron is not among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. Accordingly, as part of registration review, EPA will issue future 

EDSP orders/data call-ins, requiring the submission of EDSP screening assays for

orthosulfamuron. For further information on the status of the EDSP, the policies and procedures, 

the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, please 

visit our website: http://www.epa.gov/endo/. 

XIV. Preliminary Identification of Data Gaps  

A. Fate

Several fate studies are needed to better characterize the environmental fate and transport of 

orthosulfamuron. The studies listed below will decrease the uncertainty in determining the 

potential exposure to the pesticide. 

• Hydrolysis (OPPTS22 Guideline 835.2120) for parent at pH 5 and 25o

C 

• Aerobic Soil Metabolism (OPPTS Guideline 835.4100) for parent 

• Anaerobic Aquatic Metabolism (OPPTS Guideline 835.4400) for parent 

• Batch Equilibrium (OPPTS Guideline 835.1240) for the orthosulfamuron degradates 

DBS acid and DOP urea. 

• Aquatic Field Dissipation (OPPTS Guideline 835.6200) for parent 

• Environmental Chemistry Methods for Soil and Water (OPPTS Guideline 850.7100) for 

parent and major degradates to support aquatic field dissipation study 

• Environmental Chemistry Methods for Water (OPPTS Guideline 850.7100) for parent 

and major degradates 

Table 8 summarizes the fate data requirements for orthosulfamuron. A rationale discussing the 

need for each study is also provided below. 

Table 8. Summary of Submitted Environmental Fate Studies, Study Classifications and 

Data Gaps for Orthosulfamuron and Its Degradates 

OPPTS 

Guideline

MRID Study 

Classification

Comments on Study 

Classification 

Data 

Gap? 

Comments 

Hydrolysis 

835.2120 

(161-1) 

46219015 Supplemental Values may be used in 

risk assessment. 

Yes Data are needed at pH 5 at 

25o

C. 

46578970 Unacceptable No material balance. Did 

not follow degradates. 

46219016 Supplemental Study conducted at 50oC

 

22 Office of Prevention, Pollution, and Toxic Substances (OPPTS) is not the Office of Chemical Safety and Pollution 

Prevention (OCSPP); however, the guidelines still reference the OPPTS office. 
49 

OPPTS 

Guideline

MRID Study 

Classification

Comments on Study 

Classification 

Data 

Gap? 

Comments 

Aqueous 

Photolysis 

835.2370 

(161-2) 

46588509 Supplemental Many deficiencies but 

adequate to determine 

that this is not a 

significant pathway of 

degradation. 

No None 

Soil Photolysis 

835.2410 

(161-3) 

Not applicable Not applicable None No 40 CFR Part 158.1300 does 

not require this study for 

aquatic uses. 

Aerobic Soil 

Metabolism 

835.4100 

(162-1) 

Not applicable Not applicable None Yes No data submitted. 

Anaerobic Soil 

Metabolism 

835.4200 

(162-2) 

Not applicable Not applicable None No 40 CFR Part 158.1300 does 

not require this study for 

aquatic uses. 

Aerobic Aquatic 

Metabolism 

835.4300 

(162-4) 

46219017 Supplemental Unextracted residues 

made up to 33% applied 

radioactivity and a 

reasonable attempt was 

not made to fully extract 

all radioactivity. 

No There is still some uncertainty 

as to the identity of the 

unextracted residues. 

Providing more information 

on the identity of the 

unextracted residues may 

reduce the duration of the 

estimated half-life and/or 

change maximum amounts of 

degradates observed. 

46588508 Unacceptable Conducted outdoors with 

fluctuation temperatures 

and sunlight. 

Anaerobic 

Aquatic 

Metabolism 

835.4400 

(162-3) 

46578967 Supplemental Numerous deficiencies 

including use of soil 

instead of sediment. 

Yes Available data do not fulfill 

the guideline requirement due 

to numerous deficiencies. 

Sorption 

coefficients 

835.1240 

(163-1) 

46219074 Supplemental Many deficiencies 

including use of foreign 

soil. Values may be used 

quantitatively. 

Yes Batch equilibrium data are 

needed to estimate exposure 

to DBS acid and DOP urea. 

These were the residues with 

the highest percentages 

observed in fate studies. Data 

are not needed for the parent. 

46578971 Supplemental Material balance and 

stability only determined 

in supplementary 

experiment. Values may 

be used quantitatively. 

Aged Column 

Leaching 46219018 Acceptable None No None 

Soil Column 

Leaching 46578968 Supplemental Only one ring labeled. No None 
50 

OPPTS 

Guideline

MRID Study 

Classification

Comments on Study 

Classification 

Data 

Gap? 

Comments 

Aquatic Field 

Dissipation 

835.6200 

46578985 Supplemental Associated ECM and ILV 

are not available for soil 

and water. Recoveries in 

field spikes were low and 

variable. 

Yes A study is needed with an 

associated sediment/soil and 

water ECM and ILV. If the 

storage stability data indicate 

that compounds are not stable 

during storage, field spikes 

should be obtained and 

extracted with each set of 

samples collected. 

Bioconcentration 

Factor 

850.1730 

46588507 Acceptable None No None 

Environmental 

Chemistry 

Method: Water 

850.7100 

None submitted Not applicable None Yes An ECM and ILV are needed 

with a limit of quantitation 

(LOQ) for the parent below 

0.2 μg/L that may be used in 

monitoring.2

 A method is also 

needed to support an aquatic 

field dissipation study. The 

method may be the same 

method. All major degradates 

should be included in the 

method and have an 

associated LOQ and limit of 

detection (LOD). 

Environmental 

Chemistry 

Method: Soil 

and sediment 

850.7100 

None submitted Not applicable None Yes An ECM and ILV are needed 

with associated LOQ and 

LOD for all major degradates 

for soil and sediment. The 

method(s) is needed to 

support the aquatic field 

dissipation study. 

Abbreviations: ECM=Environmental Chemistry Method; ILV=independent laboratory Validation 

1

 Water and sediments were not fully characterized and collection procedures (sampling depth, temperature, 

dissolved oxygen content, and microbial biomass) were not reported. Unextracted residues were 43%. Limit of 

quantitation not reported. 

2 The LOQ was based on the NOAEC for aquatic vascular plants (NOAEC = 0.00026 mg a.i./L) and an LOC of 1 

(MRID 46578939 and 46578940). 

1. Rationales for Requesting Fate Studies 

• Hydrolysis (OPPTS Guideline 835.2120) for parent at pH 5 and 25oC 

Data are not available to determine the rate of hydrolysis for the parent compound at 25o

C and 

pH 5. A preliminary study at 50oC and pH 4 indicates that significant hydrolysis may occur at 

low pH (MRID 46219015). Therefore, this study is needed to characterize the potential for 

hydrolysis in the aquatic environment at low pH. Additionally, this is a standard data 

requirement for outdoor use patterns (40 CFR Part 158.1300). 

 
51 

• Aerobic Soil Metabolism (OPPTS Guideline 835.4100) for parent 

This is a standard data requirement for terrestrial and aquatic use patterns and no data have been 

submitted to support this data requirement (40 CFR Part 158.1300). Data are needed to identify 

potential degradates and to better understand the potential for aerobic soil metabolism when 

orthosulfamuron is applied to dry soils. 

• Anaerobic Aquatic Metabolism (OPPTS Guideline 835.4400) for parent 

The available anaerobic aquatic metabolism study (MRID 46578967) has numerous deficiencies 

including the following: 

• Unextracted residues ranged from not detected to 43% applied radioactivity. Reasonable 

attempt to extract all residues was not made. 

• Soils instead of sediment were used in the study. 

• Microbial biomass was not determined in soil or water. 

• Limit of quantitation not reported. 

• Collection procedures (sampling depth) and temperature, dissolved oxygen content, and 

microbial biomass were not reported for water or sediment. 

The study is the only study available examining anaerobic metabolism rates and does provide 

some useful information on the identity of anaerobic metabolites. Based on the multiple 

uncertainties with the available study, a study is still needed to accurately predict anaerobic 

aquatic metabolism rates and potential transformation products for anaerobic metabolism. 

• Batch Equilibrium (OPPTS Guideline 835.1240) for DBS acid and DOP urea 

The human health risk and ecological risk assessments identified all major degradates as residues 

of concern for orthosulfamuron. Column leaching studies of aged orthosulfamuron indicated 

that some degradates (DBS acid, DBS amide, and o-desmethyl orthosulfamuron) are capable of 

greater mobility than the parent and are more likely to leach to ground water (MRID 46219018). 

DBS acid was a major degradate in hydrolysis, aerobic aquatic, and anaerobic aquatic 

metabolism studies where it was detected at maximums of 86%, 61%, and 39% of applied parent 

equivalents, respectively. DOP urea was a major degradate in hydrolysis, aerobic aquatic, and 

anaerobic metabolism studies where it was detected at maximums of 78% at pH 4, 47%, and 

12% of applied parent equivalents, respectively. Additionally, EPIsuite estimated KOC values for 

these degradates were 0.09 and 53 L/kg-OC, suggesting that they have the potential to be more 

mobile than the parent (Appendix A). Therefore, data on the sorption coefficients of these 

degradates are needed to estimate concentrations of total toxic residues in water. O-desmethyl 

orthosulfamuron is expected to have similar mobility to the parent; therefore, data on the parent 

compound may be used to estimate exposure. DBS amide was detected at a maximum of 10% in 

one hydrolysis study and was a minor degradate in all other studies; therefore, data were not 

requested for this degradate. O-desmethyl DOP urea is a minor degradate that is a residue of 

concern for some aquatic organisms. The only difference in structure between DOP urea and odesmethyl DOP urea is a methyl group; therefore, data on DOP urea may be used to predict 

exposure for o-desmethyl DOP urea. DOP amine was only a major degradate in the hydrolysis 
52 

study conducted at pH 9 and was a minor degradate (<1% applied radioactivity) in aerobic and 

anaerobic systems and DOP amine was not identified as a residue of concern for human health; 

therefore, data are not needed for DOP amine. 

• Aquatic Field Dissipation (OPPTS Guideline 835.6200) 

• Environmental Chemistry Methods for Soil and Water (OPPTS Guideline 850.7100) to 

support aquatic field dissipation study 

This is a standard data requirement for terrestrial and aquatic use patterns and submitted data are 

not adequate to fulfill this requirement (40 CFR Part 158.1300). Storage stability data for the 

submitted study did not demonstrate stability of the parent and transformation products for the 

maximum storage interval of test samples. Recoveries of field fortifications ranged from 51-

82% for orthosulfamuron, 48-92% for DOP urea (IR7825), and 16-68% for DBS acid 

(IR7863).23 Additionally, environmental chemistry methods and associated independent 

laboratory validations are not available for the methods used in the aquatic field dissipation study 

and this is a requirement for acceptable aquatic field dissipation studies.24 Finally, the aquatic 

field dissipation study did not look for all major degradates and transformation products 

identified as residues of concern and limit of quantitations (LOQ) for some residues were high. 

An aquatic field dissipation study is needed with associated environmental chemistry methods 

with LOQ that are low enough to cover the levels of degradates and the parent that could result 

in a risk concern (e.g., toxicity endpoint x LOC). The method should be evaluated by an 

independent laboratory. If storage stability or recoveries from extraction methods are poor or 

variable, a method should be used to correct for these issues in the study. For example, field 

spikes could be performed with the collection of each set of samples and matrix spikes or 

surrogate internal standards25 could be used to monitor extraction recoveries in the lab. The 

current study may be found to be adequate to fulfill the guideline requirement for the current 

proposed uses if ECM and associated ILV are provided and the issues with the variable and low 

recoveries of field spikes samples and storage stability studies are addressed. 

• Environmental Chemistry Methods for Water (OPPTS Guideline 850.7100) 

An ECM and ILV are needed with a limit of quantitation (LOQ) for the parent below 0.2 μg/L 

that may be used in monitoring. LOQ for residues of concern should be low enough to cover the 

concentration that could result in a risk concern (e.g., toxicity endpoint multiplied by the LOC). 

A method and associated ILV is also needed to support an aquatic field dissipation study and the 

method evaluated must be the same method used in the aquatic field dissipation study. One 

method may be used to fulfill both data needs. All major degradates should be included in the 

method and have an associated LOQ and limit of detection (LOD). 

 

23 See Table 13 on page 20 of data evaluation record for MRID 46578985. 

24 Method validation studies were available for orthosulfamuron and IR7825. Samples were shaken in 

dichloromethane, decanted, and shaken again. Extracts were combined, concentrated, reconstituted in 

acetonitrile:aqueous NaHCO3, and analysis by LC/MS/MS. Field samples were analyzed directly using LC/MS/MS. 

However, this is not the method used for study samples. 

25 Surrogate internal standards are compounds that are similar in chemical composition to the analyte of interest and 

are spiked into each sample prior to preparation and analysis. They are used to evaluate matrix interference and/or 

extraction method quality for each sample or batch of samples and are a method of dealing with variable extraction 

recoveries. 
53 

B. Effects

Several ecological effects studies on orthosulfamuron are needed to better assess the potential 

risk of orthosulfamuron exposure to non-target organisms. The studies listed below should be 

submitted to increase certainty in the risk estimation. Effects studies need for the degradates are 

discussed in Section B.3.. 

• Special Study for Non-Target Plant Reproductive Toxicity (Non-Guideline) for TEP 

• Freshwater Fish-Acute Toxicity (850.1075) with the TEP 

• Freshwater Invertebrates-Acute Toxicity (850.1010) with the TEP 

• Terrestrial Plant Toxicity-Tier II Vegetative Vigor (850.4150) 

The following studies are standard data requirements for orthosulfamuron; however, data are not 

requested for these at this time. 

• Avian Acute Oral Toxicity Test with a Passerine Species (850.2100) 

• Saltwater Fish-Acute Toxicity (850.1075) with the TEP 

• Saltwater Invertebrates-Acute Toxicity (850.1025, 850.1035) with the TEP 

• Whole sediment survival, growth, and reproduction tests with TGAI and Chironomus 

tentans, Leptocheirus plumulosus, and Hyalella Azteca

If application rates change or new uses are proposed in the future, then these data may be 

required. 

Table 9 summarizes the effects data requirements for orthosulfamuron. Rationales discussing the 

data requirements are provided after Table 9. 

Table 9. Summary of Submitted Ecological Effects Studies and Data Gaps for Parent 

Orthosulfamuron 

OPPTS Guideline MRID Study 

Classification

Data Gap? Comments for Data Gap 

Terrestrial Animals 

850.2100 

Avian Oral Toxicity 

– Waterfowl or 

Upland Game Bird 

46260107 Acceptable No 

850.2100 

Avian Acute Toxicity 

- Passerine 

No Data NA No See discussion below regarding acute toxicity for 

passerines. 

850.2200 

Avian Dietary 

Toxicity 

46219040 Acceptable No 

850.2300 

Avian Reproduction 

46578949 

46578950 

Acceptable 

Acceptable 

No 
54 

OPPTS Guideline MRID Study 

Classification

Data Gap? Comments for Data Gap 

850.3020 

Honeybee Acute 

Contact Toxicity 

46219046 Acceptable No 

Aquatic Animals 

850.1075 

Freshwater Fish-Acute 

Toxicity 

46219042 Acceptable Yes An additional study for the TEP is required as the 

use pattern includes direct application to water 

(rice cultivation). 

850.1075 

Saltwater Fish-Acute 

Toxicity 

46578951 Acceptable No 

850.1010 

Freshwater 

Invertebrates-Acute 

Toxicity 

46219044 Acceptable Yes An additional study for the TEP is required as the 

use pattern includes direct application to water 

(rice cultivation). 

850.1025 

850.1035 

Saltwater 

Invertebrates-Acute 

Toxicity 

46578957 

46578952 

Acceptable No 

850.1300 

Freshwater 

Invertebrates-Life 

Cycle Test 

46578956 Acceptable No 

850.1350 

Saltwater 

Invertebrates-Life 

Cycle Test 

46578954 Supplemental No 

850.1400 

Freshwater Fish-Early 

Life Stage Test 

46578953 Acceptable No 

850.1500 

Fish-Life Cycle Test 

No Data NA No 

Plants 

850.4100 

Terrestrial Plant 

Toxicity-Tier 1 

Seedling Emergence 

46578941 Acceptable No 

850.4225 

Terrestrial Plant 

Toxicity-Tier 2 

Seedling Emergence 

46578941 Acceptable No 

850.4150 

Terrestrial Plant 

Toxicity-Tier 1 

Vegetative Vigor 

46578942 Supplemental No Study classified as supplemental due to lack of a 

NOAEC for several species. A Tier II study with 

a definitive NOAEC is needed. 

850.4150 Terrestrial 

Plant Toxicity-Tier 2 

Vegetative Vigor 

46578942 Supplemental Yes Study classified as supplemental due to lack of a 

NOAEC for several species. 
55 

OPPTS Guideline MRID Study 

Classification

Data Gap? Comments for Data Gap 

(Non-Guideline) 

Special Study-NonTarget Plant 

Reproductive Toxicity 

No Data Yes See rationale below. 

850.4400 

Aquatic Plant GrowthAlgae 

46578935 

46578936 

Supplemental 

Supplemental 

No 

850.4400 

Aquatic Plant GrowthVascular Plants 

46578939 Acceptable No 

1. Rationales for Requesting Effects Studies 

• Special Study for Non-Target Plant Reproductive Toxicity (Non-Guideline) for TEP 

Investigations/studies have indicated that a small percentage of the label application rate of low 

dose, high-potency herbicides such as orthosulfamuron may impact the reproduction of nontarget terrestrial plants. However, there are no available data on adverse reproductive impacts to 

terrestrial plants from orthosulfamuron residues due to spray drift. Terrestrial plant reproductive 

toxicity data would help to screen for potential plant risks. Plants form the basis of most habitats 

and contribute significantly to overall environmental quality. The loss of plant reproductive 

output could potentially have an adverse effect on animals, both invertebrates and vertebrates, as 

many are dependent on plant reproduction as a food source and for habitat quality and structure. 

A solid understanding of the potential risks to plants is therefore essential. Thus, a special study 

for non-target plant reproductive toxicity (non-guideline) with the TEP is required. 

Terrestrial plant reproductive toxicity data would help to screen for potential plant risks. Plants 

form the basis of most habitats and contribute significantly to overall environmental quality. The 

loss of plant reproductive output could potentially have an adverse effect on animals, both 

invertebrates and vertebrates, as many are dependent on plant reproduction as a food source and 

for habitat quality and structure. A solid understanding of the potential risks to plants is therefore 

essential. A special study for non-target plant reproductive toxicity (non-guideline) is needed to 

reduce this uncertainty. 

• Freshwater Fish-Acute Toxicity (850.1075) with the TEP 

It is stated in 40 CFR Part 158.630 that studies with the TEP should be conducted on all aquatic 

animals (as evidenced from the TGAI data) for a particular taxon (e.g., freshwater fish, 

freshwater invertebrates and estuarine/marine organisms). Thus, an acute toxicity study in 

freshwater fish is required for any end-use product which will be introduced directly into an 

aquatic environment. Orthosulfamuron will be applied to rice paddies that may be flooded with 

freshwater; therefore, this study is required. While orthosulfamuron is not expected to result in 

direct effects to fish, there is significant uncertainty regarding the toxicity of the TEP to aquatic 

organisms. This study is requested in order to understand the toxicity of the end-use product as a 

whole, which may have very different toxicity proprerties as compared to orthosulfamuron alone. 

When a product is applied directly to water aquatic organisms will be exposed to the entire 
56 

product. It is not known whether toxicity data on the parent alone will reflect the toxicity of the 

entire product; therefore, the risk estimated for the parent alone does not inform whether data on 

the product are needed when a product is applied directly to water. Therefore, data on the TEP 

are requested for freshwater fish. Data will be used to address the uncertainty regarding the 

potential enhanced toxicity of the TEP. If the data show that the TEP is more toxic than the 

TGAI, TEP toxicity data would be used to evaluate acute risk to fish exposed to 

orthosulfamuron. 

• Freshwater Invertebrates-Acute Toxicity (850.1010) with the TEP 

It is stated in 40 CFR Part 158.630 that studies with the TEP should be conducted on all aquatic 

animals (as evidenced from the TGAI data) for a particular taxon (e.g., freshwater fish, 

freshwater invertebrates and estuarine/marine organisms). Thus, an acute toxicity study in 

freshwater invertebrates is required for any end-use product which will be introduced directly 

into an aquatic environment. Orthosulfamuron will be applied to rice paddies that may be 

flooded with freshwater; therefore, this study is required. While orthosulfamuron is not expected 

to result in direct effects to aquatic invertebrates, there is significant uncertainty regarding the 

toxicity of the TEP to aquatic organisms. Therefore, data on the TEP are requested for 

freshwater invertebrates. Data will be used to address the uncertainty regarding the potential 

enhanced toxicity of the TEP. If the data show that the TEP is more toxic than the TGAI, TEP 

toxicity data would be used to evaluate acute risk to freshwater invertebrates exposed to 

orthosulfamuron. 

 

• Terrestrial Plant Toxicity-Tier 2 Vegetative Vigor (850.4150) 

A terrestrial plant vegetative vigor study was submitted for orthosulfamuron but was classified as 

supplemental due to a lack of definitive NOAEC in the most sensitive species, carrot and radish. 

Also, for soybean and pea height and mung bean dry weight, the EC25 was lower than the lowest 

treatment level (<0.0017 lb a.i./A) and could not be determined. Therefore, this study is required. 

2. Rationales for Not Requesting Effects Studies 

• Avian Acute Oral Toxicity Test with a Passerine Species (850.2100) 

According to the 40 CFR 158, acute oral toxicity data are required for a passerine species. 

Because no acute oral toxicity data have been submitted for a passerine species exposed to 

orthosulfamuron, this is a data gap. No acute oral toxicity data involving orthosulfamuron or its 

degradates have been identified in the scientific literature (using ECOTOX). 

Available acute oral toxicity data for birds (MRID 46260107 and 46219040) indicate that 

orthosulfamuron is classified as slightly toxic or practically nontoxic to the mallard duck and the 

bobwhite quail on an acute oral exposure basis. In addition, in a sub-acute toxicity study (MRID 

46219040) with the mallard duck, no mortalities were observed at the highest test levels (i.e.,

4790 mg a.i./kg-food). In addition, no sublethal effects were observed in these studies. 

Given the low application rate of orthosulfamuron (i.e., 0.067 lb a.i./A), it is expected that the 
57 

exposure of birds to orthosulfamuron will be low (dose-based EEC for birds is 18.31 mg/kg/day 

based on T-REX version 4.1.1). The lowest acute values for birds are 1960 mg a.i./kg-bw 

(highest dose tested) for acute oral and 4790 mg a.i./kg-diet (highest dose tested) for subacute 

dietary; the corresponding NOAEC values for these studies are both 1280 mg a.i./kg-diet (no 

mortality or frank toxicity was observed). As the acute oral toxicity values are based on body 

weight, the NOAEL value for the avian acute oral was entered into T-REX to obtain the adjusted 

toxicity value for the small weight bird assessed in T-REX. The adjusted acute toxicity value for 

birds (20-g) is 1412 mg a.i./kg-bw. The acute toxicity value for birds is at least 75 times the 

EEC.26 In order for orthosulfamuron to pose an acute risk to birds, passerines would have to be at 

least 11 to 33 times more sensitive to orthosulfamuron as compared to mallard ducks and 

bobwhite quail. Given the pattern of acute toxicity of orthosulfamuron to aquatic and terrestrial 

vertebrates, the weight of evidence suggests that orthosulfamuron will be relatively nontoxic to 

passerine species as well. 

No ecological incidents involving birds exposed to orthosulfamuron or its degradates have been 

identified. 

Therefore, EFED is not requesting oral toxicity data for passerines exposed to orthosulfamuron 

or its degradates. 

• Saltwater Fish-Acute Toxicity (850.1075) with the TEP 

• Saltwater Invertebrates-Acute Toxicity (850.1025, 850.1035) with the TEP 

According to the 40 CFR Part 158.630, acute aquatic toxicity data are required for freshwater 

and saltwater organisms examining exposure to the TEP when a product may be applied directly 

to water, the EEC in the aquatic environment is ≥ one-half the LC50 or EC50 of the Technical 

Grade Active Ingredient (TGAI) when the end product is used as directed, or an ingredient in the 

end-use product other than the active ingredient is expected to enhance the toxicity of the active 

ingredient. Orthosulfamuron will be applied to rice paddies that will typically be flooded with 

freshwater. As orthosulfamuron is not expected to result in direct effects to aquatic organisms, 

data on orthosulfamuron TEP for freshwater organisms is requested at this time, and data on 

marine/estuarine fish and invertebrates will be requested if further data are needed. 

• Whole sediment survival, growth, and reproduction tests with TGAI and Chironomus 

tentans, Leptocheirus plumulosus, and Hyalella azteca

According to 40 CFR Part 158.630, chronic sediment toxicity data are required when the half-life 

of pesticide in sediment greater 10 days and 1) the Kd is ≥50 L/kg, 2) the KOC ≥1000 L/kg, or the 

KOW ≥1000. One out of ten measured KOC values was 2145 L/kg-oc and the half-live in 

sediment is greater than 10 days, indicating that whole chronic sediment toxicity data may be 

needed. The outlying KOC was measured in a soil collected in Arkansas that had a pH of 5.66 

and a low organic carbon content of 0.35%. While the measured value may occur near or in an 

intended use site as rice is commonly grown in Arkansas, most rice paddies are expected to have 

a much higher organic matter content. Additionally, aquatic invertebrate toxicity data indicate 

 

26 For the lowest ratio for acute terrestrial animals (acute avian oral): 1412 ÷ 18.86 = 74.87 
58 

that exposure is highly unlikely to be high enough to result in a risk concern. Therefore, whole 

chronic sediment toxicity data are not requested at this time. This may be reevaluated in the 

future if exposure estimates or toxicity data indicate that residues in sediment could result in a 

risk concern. 

3. Degradate Toxicity Data 

As discussed in Section XI Identification of Stressors of Concern, data on DOP urea was 

identified to be needed in order to conduct the risk assessment as exposure to ureas could alter 

the risk conclusions from those evaluated for the parent alone. The following studies are needed 

to assess risk due to exposure to DOP urea and o-desmethyl DOP urea. 

• Freshwater Invertebrates-Acute Toxicity (OPPTS Guideline 850.1010) with DOP urea 

Aquatic Invertebrate Life Cycle (Freshwater) (OPPTS Guideline 850.1300) with DOP 

urea 

• Fish Early Life Stage (Freshwater) (OPPTS Guideline 850.1400) with DOP urea 

• Tier I and/or II Aquatic Plant Growth (OPPTS Guideline 850.4400) with nonvascular 

plants and DOP urea 

Table 10 summarizes the effects data requirements for orthosulfamuron degradates. A brief 

rational for each data requirement is provided below. A more detailed discussion is available in 

Section XI; Identification of Stressors of Concern. 

Table 10. Summary of Submitted Ecological Effects Studies and Data Gaps for 

Orthosulfamuron Degradates 

OPPTS Guideline MRID Study 

Classification

Data Gap? Comments for Data Gap 

Aquatic Animals 

850.1010 

Freshwater 

Invertebrate – Acute 

Toxicity 

No Data NA Yes Data on DOP urea are needed to assess potential 

risk due to exposure to DOP urea and odesmethyl DOP urea. See Section XI for a full 

discussion. 

850.1300 

Freshwater 

Invertebrates-Life 

Cycle Test 

No data NA Yes 

850.1400 

Freshwater Fish-Early 

Life Stage Test 

No data NA Yes 

Plants 

850.4150 Terrestrial 

Plant Toxicity-Tier I 

and/or II Vegetative 

Vigor 

No data NA Yes Data on DOP urea are needed to assess potential 

risk due to exposure to DOP urea and odesmethyl DOP urea. See Section XI for a full 

discussion. A Tier I data may be sufficient to 

fulfill this guideline if less than 50% effects are 

observed at the highest EEC. 
59 

OPPTS Guideline MRID Study 

Classification

Data Gap? Comments for Data Gap 

850.4400 

Aquatic Plant Growth- No data NA Yes Data on DOP urea are needed to assess potential 

risk due to exposure to DOP urea and odesmethyl DOP urea. See Section XI for a full 

discussion. 

• Tier I and/or II Aquatic Plant Growth (OPPTS Guideline 850.4400) with nonvascular 

plants and DOP urea 

Concentrations of urea residues considering maximum amounts of DOP urea, o-desmethyl DOP 

urea, and unextracted were estimated to range from 10-15 μg/L (Appendix F). Measured 

nonvascular plant Aquatic Life Benchmarks for ureas range from 2.4 to 80 μg/L. This indicates 

that degradate concentrations have the potential to be present at high enough to cause a risk 

concern for non-vascular aquatic plants. Tier I data may be sufficient to fulfill this guideline if 

less than 50% effects are observed at the highest EECs. Therefore, data will be requested on 

DOP urea for nonvascular aquatic plants. To estimate risk due to exposure to the ureas for 

aquatic organisms, an EEC will be estimated considering exposure to both DOP urea and odesmethyl DOP urea and the EEC will be compared to effects data for DOP urea. 

• Freshwater Invertebrates-Acute Toxicity (OPPTS Guideline 850.1010) with DOP urea 

• Aquatic Invertebrate Life Cycle (Freshwater) (OPPTS Guideline 850.1300) with DOP 

urea 

• Fish Early Life Stage (Freshwater) (OPPTS Guideline 850.1400) with DOP urea 

Chronic ALBs27 for some urea herbicides (range from 0.09 to 21,800 μg/L) are much lower than 

those for orthosulfuramuron (range from 6,100 to 6,500 μg/L) (Appendix B).28 EECs for ureas 

ranged from 10 to 15 μg/L. Acute ALBs for some urea herbicides for freshwater invertebrates 

indicate there is a potential for concentrations to be high enough to result in a risk concern. 

Therefore, chronic toxicity data for DOP urea are needed for aquatic animals and acute toxicity 

data for freshwater invertebrate are needed. 

4. Testing on Typical end-use products (TEP) 

A Typical End-Use Product is defined in the Pesticide Assessment Guidelines Subdivision J 

Hazard Evaluation: Nontarget plants on Part 120-2(1) on Page 18 as “a pesticide product that is 

representative of a major formulation category (e.g., emulsifiable concentrate, granular product, 

wettable powder) and pesticide group (e.g., herbicide, fungicide, insecticide etc.) and contains 

 

27 Benchmarks, developed for baseline risk assessments, are estimates of the concentrations below which pesticides 

are not expected to harm aquatic life. Each Aquatic Life Benchmark is based on the most sensitive, scientifically 

acceptable toxicity endpoint available to EPA for a given taxon (for example, freshwater fish) of all scientifically 

acceptable toxicity data available to EPA multiplied by the corresponding level of concern of 0.5 for acute endpoints 

and 1.0 for chronic and plant endpoints. Aquatic life benchmarks may be found at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm. 28 Three of six chronic values ranged from 0.09 – 26 μg/L and were in the range of EECs estimated for ureas of 10 

to 15 μg/L. 
60 

the active ingredient of the applicant’s product.” (Holst and Ellwanger, 1982) 

Page 5 of the Pesticide Assessment Guidelines Subdivision J Hazard Evaluation: Nontarget 

plants provides additional information on what TEP data should be tested for toxicity testing in 

the following excerpt. 

 “The Agency seeks to avoid imposing a burden of duplicative testing on applicants for 

registration. Therefore, where 40 CFR Part 158 specifies that the test substance should be a 

representative end-use product, testing may be performed using the formulation in question (enduse product being registered) or similar, yet representative, end-use product. It is not necessary 

to repeat the test using other similar products.” (Holst and Ellwanger, 1982) 

When TEP data are requested data should be submitted for the different formulations, e.g., 

wettable powder, emulsifiable concentrate, granular, along with a rationale as to why the TEP is 

representative of other similar end-use products. 

XV.  Other Information Needs

There is specific information that will assist the Agency in refining the ecological risk 

assessment, including any species-specific effects determinations. The Agency is very much 

interested in obtaining the following information: 

1. confirmation on the following label information 

a. frequency of application, application intervals, and maximum number of 

applications per season 

b. geographic limitations on use 

2. use or potential use distribution (e.g., acreage and geographical distribution of relevant 

crops) 

3. use history 

4. median and 90th percentile reported use rates (lbs. a.i./acre) from usage data – national, 

state, and county 

5. application timing (date of first application and application intervals) by crop – national, 

state, and county 

6. sub-county crop location data 

7. directly acquired county-level usage data (not derived from state level data) 

a. maximum reported use rate (lbs. a.i./acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county 

e. the year the pesticide was last used in the county/sub-county area 

f. the years in which the pesticide was applied in the county/sub-county area 

8. state or local use restrictions 

9. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency 

10. monitoring data 

 In order to assess the risk to terrestrial organisms exposed to granules the weight of one granule 
61 

for each granule formulation would be useful. 

XV.  References  

Armitage, J. M., & Gobas, F. A. P. C. 2007. A terrestrial food-chain bioaccumulation model for 

POPs. Environmental Science and Technology, 41, 4019-4025. 

Asghari, J. B., & Evans, J. O. 1992a. Dyer’s woad (Isatis tinctoris L.) pollen viability is reduced 

by metsulfuron methyl application. Research Progress Report on the Western Society of 

Weed Science. Meeting March 9-12. Salt Lake City Utah, 178-179. 

Asghari, J. B., & Evans, J. O. 1992b. Effect of metsulfuron methyl on seed formation and 

viability of Dyer’s woad (Isatis tinctoria L.) in the field. Research Progress Report of the 

Western Society of Weed Science. Meeting March 9-12, 1992. Salt Lake City, UT, III178-II-179. 

Bhatti, M. A., Al-Khatib, K., Felsot, A. S., Parker, R., & Kadir, S. 1995. Effects of simulated 

chlorsulfuron drift on fruit yield and quality of sweet cherries (Prunus avium L.). 

Environmental Toxicology and Chemistry, 14(3), 537-544. 

Boutin, C., Lee, H. B., Peart, E. T., Batchelor, P. P., & Maguire, R. J. 2000. ffects of the 

sulfonylurea herbicide metsulfuron methyl on growth and reproduction of five wetland 

and terrestrial plant species. Environmental Toxicology and Chemistry, 19(10), 2532-

2541. 

Fletcher, J. S., Nellessen, J. E., & Pfleeger, T. G. 1994. Literature review and evaluation of the 

EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on 

plants. Environmental Toxicology and Chemistry, 13(9), 1383-1391. 

Fletcher, J. S., Pfleeger, T. G., & Ratsch, H. C. 1993. Potential environmental risks associated 

with the new sulfonylurea herbicides. Environmental Science and Technology, 27(10), 

2250-2252. 

Fletcher, J. S., Pfleeger, T. G., Ratsch, H. C., & Hayes, R. 1996a. Chlorsulfuron influence on 

garden pea reproduction. Physiologia Plantarum, 94, 261-267. 

Fletcher, J. S., Pfleeger, T. G., Ratsch, H. C., & Hayes, R. 1996b. Potential impact of low levels 

of chlorsulfuron and other herbicides on growth and yield of nontarget plants. 

Environmental Toxicology and Chemistry, 7, 1189-1196. 

Hoerger, F., & Kenaga, E. E. 1972. Pesticide Residues on Plants: Correlation of Representative 

Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston & 

F. Korte (Eds.), Environmental Quality and Safety: Chemistry, Toxicology, and 

Technology (Vol. 1, pp. 9-28). New York: Academic Press. 

ISAGRO. Orthosulfamuron Technical Bulletin. Memorandum From to Available at 

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tin%20may2010.pdf (Accessed June 20, 2011). 

NCI/CADD Group. 2011. Online SMILES Translator and Structure File Generator: National 

Cancer Institute. National Institute of Health. Center for Cancer Research. Available at 

http://cactus.nci.nih.gov/translate/ 

Pfleeger, T., Olszyk, D., Lee, E. H., & Plocher, M. 2011. Comparing effects of low levels of 

herbicides on greenhouse- and field-grown potatoes (Solanum tuberosum L.), soybeans 

(Glycine max L.), and peas (Pisum sativum L.). Environmental Toxicology and 

Chemistry, 30(2), 455-468. 
62 

Teske, M. E., & Curbishley, T. B. 2003. AGDISP Version 8.07 User Manual. Prepared For 

United States Department of Agriculture Forest Service. C.D.I. Technical Note No. 02-

06. June 2003. 

USEPA. 1993. Wildlife Exposure Handbook, United States Environmental Progection Agency. 

Washington, D.C.: Government Printing Office. Available at 

http://www.epa.gov/ncea/pdfs/toc2-37.pdf (Accessed June 19, 2009). 

USEPA. 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. United States 

Environmental Protection Agency (USEPA). Risk Assessment Forum. Office of 

Research and Development. Available at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12460 (Accessed June 19, 2009). 

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

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

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

http://www.epa.gov/espp/consultation/ecorisk-overview.pdf (Accessed June 19, 2009). 

USEPA. 2006.D333514. Environmental Fate and Ecological Risk Assessment for the 

Registration of Orthosulfamuron. D333514. December 28, 2006. Environmental Fate and 

Effects Division, Office of Pesticide Programs, United States Environmental Protection 

Agency. 

USEPA. 2006.330828. Orthosulfamuron (Section 3: Rice Use) Tier I Drinking Water Exposure 

Assessment for Orthosulfamuron on Rice. 330828. Memorandum From G. Orrick to J. 

Tompkins & K. Bailey. Environmental Fate and Effects Division. Office of Prevention, 

Pesticides, and Toxic Substances. United States Environmental Protection Agency. 

USEPA. 2007a. Ecological Incident Information System. United States Environmental 

Protection Agency. Available at http://www.epa.gov/espp/consultation/ecoriskoverview.pdf (Accessed June 19, 2009). 

USEPA. 2007b. Guidance for Tier I Estimation of Aqueous Pesticide Concentrations in Rice 

Paddies. Memorandum From S. Bradbury to E. F. a. E. Division. Environmental Fate 

and Effects Division. Office of Pesticide Programs. United States Environmental 

Protectin Agency. Available at 

http://www.epa.gov/oppefed1/models/water/rice_tier_i.pdf (Accessed July 5, 2011). 

USEPA. 2007.D319264. Orthosulfamuron: Human Health Risk Assessment for Proposed Use 

on Rice. PC Code: 108209, Petition No: 5F6957, DP Barcode D319264. Memorandum 

From K. J. Bailey, D. Dotson & Z. Figueroa to E. Kraft. Health Effects Division. Office 

of Prevention, Pesticides, and Toxic Substances. United States Environmental Protection 

Agency. 

USEPA. 2008a. Environmental Fate and Ecological Risk Assessment for Etofenprox New Uses 

on Rice and for Vector Control, United States Environmental Protection Agency. 

Washington, D.C. 

USEPA. 2008b. White paper on Methods for Assessing Ecological Risks of Pesticides with 

Persistent, Bioaccumulative, and Toxic Characteristics. Submitted to the FIFRA 

Scientific Advisory Panel for Review and Comment. October 7, 2008. Environmental 

Fate and Effects Division. Office of Pesticide Programs. Office of Prevention, 

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7_08d.pdf (Accessed January 27, 2010). 
63 

USEPA. 2009a. ECOTOXicology Database, United States Environmental Protection Agency 

(USEPA). Available at http://cfpub.epa.gov/ecotox/ (Accessed June 19, 2009). 

USEPA. 2009b. SAP Minutes No. 2009-01. A set of Scientific Issues Being Considered by the 

Environmental Protection Agency Regarding: Selected Issues Associated with the Risk 

Assessment Process for Pesticides with Persistent, Bioaccumulative, and Toxic 

Characteristics. October 28-31, 2008. January 29, 2009. FIFRA Scientific Advisory 

Panel. Office of Science Coordination and Policy. Available at 

http://www.epa.gov/scipoly/sap/meetings/2008/102808_mtg.htm (Accessed July 9, 

2009). 

USEPA. 2010a. BEAD Chemical Profile for Registration Review: Orthosulfamuron (108209). 

Memorandum From S. Ratnayake, S. Haddad & S. Smearman to J. Parker. May 18, 

2010. Biological and Economic Analysis Division, Office of Chemical Safety and 

Pollution Prevention. United States Environmental Protection Agency 

USEPA. 2010b. Guidance for Reporting on the Environmental Fate and Transport of the 

Stressors of Concern in the Problem Formulation for Registration Review, Registration 

Review Risk Assessments, Listed Species Litigation Assessments, New Chemical Risk 

Assessments, and Other Relevant Risk Assessments. January 25, 2010. Environmental 

Fate and Effects Division, . 

USFWS/NMFS. 1998. Endangered Species Consultation Handbook: Procedures for Conducting 

Consultation and Conference Activities Under Section 7 of the Endangered Species Act. 

Final Draft. United States Fish and Wildlife Service (USFWS) and National Marine 

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2009). 

USNLM. 2009. TOXNET Toxicology Data Network. United States National Library of 

Medicine (USNLM). Available at http://toxnet.nlm.nih.gov/ (Accessed July 9, 2009). 

Ware, G. W., & Whitacre, D. M. 2004. An Introduction to Herbicides. In E. B. Radcliffe & W. 

D. Hutchison (Eds.), The Pesticide Book (6th ed.). Willoughby, OH: MeisterPro 

Information Resources. Available at http://ipmworld.umn.edu/chapters/whitacreherb.htm

(Accessed June 19, 2009). 

Wood, A. 2009. Compendium of Pesticide Common Names. Available at 

http://www.alanwood.net/pesticides/index.html (Accessed June 19, 2009). 

Data Submitted To Support Registration 

Hydrolysis OPPTS 835.2120 

46578970 Faltynski, K. (2005) Determination of Aquatic Dissolution Rate of IR5878GR and 

pH 5 Hydrolysis Rate of IR5878 Standard. Project Number: 04/0041, FR/00292. Unpublished 

study prepared by En-Cas Analytical Laboratories, Agvise Inc and Isagro Ricerca Galliera. 67 

p. 

46219015 Castoldi, F.; Pizzingrilli, G. (2000) Hydrolysis of ((Carbon 14)-U-phenyl) IR5878 

in Buffered Solutions at pH 4, 7 and 9. Project Number: ABT/99/13. Unpublished study 

prepared by Isagro S.R.L. (Formerly Agrimont). 120 p. 
64 

46219016 Castoldi, F.; Pizzingrilli, G. (2000) Identification of Hydrolysis Compounds of 

((Carbon 14)-5-pyrimidinyl) IR5878 at pH 4, 7 and 9. Project Number: ABT/00/16. 

Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont). 100 p. 

Aqueous Photolysis OPPTS 835.2370 

46588509 Hennecke, D. (2002) Aquatic Photodegradation and Quantum Yield of IR5878: 

Final Report. Project Number: ISA/003/7/05, WD00612/000. Unpublished study prepared by 

Fraunhofer Institute for Molecular Biology and Applied Ecology. 50 p. 

Aerobic Aquatic Metabolism OPPTS 835.4300 

46219017 Scacchi, A.; Vanini, L.; Pizzingrilli, G. (2003) Aerobic Aquatic Metabolism of 

(Carbon 14)-IR5878 in Two American Soils. Project Number: MEF/02/14. Unpublished study 

prepared by Isagro S.R.L. (Formerly Agrimont). 298 p. 

46588508 Scacchi, A.; Vanini, L.; Oriolo, D. (2005) Aerobic Aquatic Degradation of (Carbon14)-IR5878 in Paddy-Field Soil Under Sunlight. Project Number: MEF/04/13, WD00612/000. 

Unpublished study prepared by Isagro Ricerca S.r.l. 198 p. 

Anaerobic Aquatic Metabolism OPPTS 835.4400 

46578967 Scacchi, A.; Soddu, R.; Pizzingrilli, G. (2003) Anaerobic Aquatic Metabolism of 

(Carbon-14)-IR5878 in Two American Soils. Project Number: MEF/02/16, A2/07/01/10. 

Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Theolab s.r.l. and 

Agenzia Regionale Prevenzione e Ambiente dell'Emilia-Romagna. 280 p. 

Batch Equilibrium Study OPPTS 835.1240 

46219074 Scacchi, A.; Pizzingrilli, G. (2000) Adsorption-desorption of (Carbon 14)-IR5878 

in Soil. Project Number: ABT/00/04. Unpublished study prepared by Isagro S.R.L. (Formerly 

Agrimont). 129 p. 

46578971 Scacchi, A.; Trucco, M. (2005) Adsorption/Desorption of (Carbon-14)-IR5878 in 

American Soils. Project Number: MEF/04/02, A2/07/01/20. Unpublished study prepared by 

Isagro S.R.L. (Formerly Agrimont). 210 p. 

Soil Column Leaching 

46219018 Scacchi, A.; Pizzingrilli, G. (2003) Aged Residue Column Leaching at (Carbon 14)-

IR5878 in an American Soil. Project Number: MEF/02/17. Unpublished study prepared by 

Isagro S.R.L. (Formerly Agrimont). 194 p 

46578968 Scacchi, A.; Vanini, L.; Pizzingrilli, G. (2004) Soil Column Leaching of (Carbon14)-IR5878. Project Number: MEF/03/17, A2/07/01/17. Unpublished study prepared by Isagro 

S.R.L. (Formerly Agrimont). 162 p. 

Aquatic Field Dissipation OPPTS Guideline 835.6200 

46578985 Cooley, T. (2005) IR5878 Field Dissipation Study in Bare Ground Rice Soil: Final 

Study Report. Project Number: ERS23044, 1204W, A3/03/00/01. Unpublished study prepared 

by Excel Research Services, Inc., PTRL West, Inc. and Shoffner Farm Research. 1014 p. 
65 

Bioconcentration Factor OPPTS Guideline 850.1730 

46588507 Dijk, A. (2004) Bioconcentration: Flow-Through Fish Test with IR5878 in Bluegill 

Sunfish (Lepomis macrochirus). Project Number: 849257, WD00612/000. Unpublished study 

prepared by RCC Umweltchemie Ag. 68 p. 

Storage Stability Studies 

46578977 Zini, G.; Crisippi, T. (2004) Storage Stability of IR7863 in Soil and Sediment 

Stored in the Dark Below -20 Degrees Celsius. Project Number: 2405, A2/06/00/07. 

Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Agvise Inc. 138 p. 

46578978 Zini, G.; Crisippi, T. (2004) Storage Stability of IR7863 in Surface Water Stored in 

the Dark Below -20 Degrees Celsius. Project Number: 2403, A2/06/00/06, SPL/1700/048. 

Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Theolab. 94 p. 

46578979 Zini, G.; Crisippi, T. (2004) Storage Stability of IR7825 in Surface Water Stored in 

the Dark Below -20 Degrees Celsius. Project Number: 2402, A2/06/00/05, SPL/1700/024. 

Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Theolab. 105 p. 

46578980 Zini, G.; Crisippi, T. (2004) Storage Stability of IR7825 in Soil and Sediment 

Stored in the Dark Below -20 Degrees Celsius. Project Number: 2404, A2/06/00/04, 

SPL/1700/24. Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Agvise 

Inc. and Agenzia Regionale Pevenzione e Ambiente dell'Emilia-Romagne. 131 p. 

46578981 Zini, G.; Crisippi, T. (2004) Storage Stability of IR5878 in Soil, Sediment and 

Surface Water Stored in the Dark Below -20 Degrees Celsius. Project Number: 2377, 

A2/06/00/03. Unpublished study prepared by Isagro S.R.L. (Formerly Agrimont) and Agvise 

Inc and Agenzia Regionale Pevenzione e Ambiente dell'Emilia-Romagne. 164 p. 

Melting Point/Melting range OPPTS Guideline 830.7200 

46219007 Evans, A.; Mullee, D. (2002) IR5878 (Technical): Determination of 

Melting/Freezing Temperature. Project Number: 1700/009. Unpublished study prepared by 

Safepharm Laboratories, Ltd. 14 p. 

Partition Coefficient OPPTS Guideline 830.7570 

46219012 Woolley, S.; Mullee, D. (2002) IR 5878 (Pure): Determination of Partition 

Coefficient. Project Number: 1700/023. Unpublished study prepared by Safepharm 

Laboratories, Ltd. 25 p. 

Water Solubility OPPTS Guideline 830.7840 

46219009 Woolley, S.; Mullee, D. (2002) IR 5878 (Pure): Determination of Water Solubility. 

Project Number: 1700/005. Unpublished study prepared by Safepharm Laboratories, Ltd. 25 p. 

Vapor Pressure OPPTs Guideline 830.7950 

46219010 Tremain, S. (2002) IR 5878 (Pure): Determination of Vapour Pressure. Project 

Number: 1700/007. Unpublished study prepared by Safepharm Laboratories, Ltd. 19 p. 
66 

Non-guideline Studies 

46219011 Woolley, S.; Mullee, D. (2002) IR 5878 (Pure): Determination of Dissociation 

Constant. Project Number: 1700/006. Unpublished study prepared by Safepharm Laboratories, 

Ltd. 7 p. 

46219021 Dotti, A. (2000) IR5878: 4-Hour Acute Inhalation Toxicity Study in the Rat. Project 

Number: R06390. Unpublished study prepared by Istituto Di Recerche Biomediche (RBM) 

"Antoine Marxer". 50 p. 

46559001 Woolley, S.; Mullee, D. (2002) IR 5878 (Pure): Determination of Spectra. Project 

Number: 1700/004, WD00612/000. Unpublished study prepared by Safepharm Laboratories 

Ltd. 33 p. 

Avian Single Dose Oral Toxicity 

46260107 Dias, N. (2001) IR5878: Acute Oral Toxicity (LD50) to the Mallard Duck. Project 

Number: IGA/003/012865. Unpublished study prepared by Huntingdon Life 

Sciences, Ltd. 38 p. 

46260108 Dias, N. (2001) IR5878: Acute Oral Toxicity (LD50) to the Bobwhite Quail. Project 

Number: IGA/004/012894. Unpublished study prepared by Huntingdon Life 

Sciences, Ltd. 43 p. 

Avian Dietary Toxicity 

46219040 Dias, N. (2001) IR 5878: Dietary Toxicity (LC50) to the Mallard Duck. Project 

Number: IGA/005, IGA/005/012373. Unpublished study prepared by Huntingdon 

Life Sciences, Ltd. 35 p. 

46219041 Rodgers, M. (2001) IR 5878: Dietary Toxicity (LC50) to the Bobwhite Quail. 

Project Number: IGA/002, IGA/002/012368. Unpublished study prepared by 

Huntingdon Life Sciences, Ltd. 41 p. 

Avian Reproduction 

46578949 Frey, L.; Martin, K.; Beavers, J.; et. al. (2003) IR-5878: A Reproduction Study with 

the Mallard: Final Report. Project Number: 544/109. Unpublished study prepared 

by Wildlife International, Ltd. 157 p. 

46578950 Frey, L.; Martin, K.; Beavers, J.; et al. (2003) IR5878: A Reproduction Study with 

the Northern Bobwhite: Final Report. Project Number: 544/108. Unpublished study 

prepared by Wildlife International, Ltd. 164 p. 

2-generation repro.-rat 

46219033 Marburger, A. (2003) IR5878: Two-Generation Reproduction Toxicity Study in the 

Rat. Project Number: 841291. Unpublished study prepared by RCC Umweltchemie 

Ag and RCC Ltd. 1170 p. 

46260106 Marburger, A.; Knuppe, C.; Nehrbass, D. (2002) IR5878: Preliminary Reproduction 

Toxicity Study in the Rat. Project Number: 841176, 80012/NED. Unpublished 

study prepared by Isagro S.P.A. 276 p. 

850.1010 Aquatic invertebrate acute toxicity, test, freshwater daphnids 
67 

46219044 Hertl, J. (2000) Final Report: Acute Toxicity of IR5878 to Daphnia magna in a 48-

hour Immobilization Test. Project Number: 8222220. Unpublished study prepared 

by Institut fuer Biologische Analytik und Consulting IBACON GmbH. 24 p. 

46219045 Meinerling, M. (2000) Final Analytical Report: Acute Toxicity of IR5878 to 

Daphnia magna in a 48-Hour Immobilization Test: (Final Report). Project Number: 

8222220A. Unpublished study prepared by Institut fuer Biologische Analytik. 18 p. 

850.1025 Oyster acute toxicity test (shell deposition) 

46578957 Palmer, S.; Kendall, T.; Krueger, H. (2004) IR5878: A 96-Hour Shell Deposition 

Test with the Eastern Oyster (Crassostrea virginica): Final Report. Project Number: 

544A/106. Unpublished study prepared by Wildlife International, Ltd. 40 p. 

850.1035 Mysid acute toxicity test 

46578952 Palmer, S.; Stence, M.; Kendall, T.; et. al. (2002) IR5878: A 96-Hour Static Acute 

Toxicity Test with the Saltwater Mysid (Americamysis bahia): Final Report. Project 

Number: 544A/108. Unpublished study prepared by Wildlife International, Ltd. 37 

p. 

850.1075 Fish acute toxicity test, freshwater and marine 

46219042 Palmer, S.; Stence, M.; Kendall, T.; et. al. (2002) IR5878: A 96-Hour Static Acute 

Toxicity Test with the Rainbow Trout (Oncorhynchus mykiss): Final Report. 

Project Number: 544A/107. Unpublished study prepared by Wildlife International, 

Ltd. 38 p. 

46219043 Palmer, S.; Kendall, T.; Krueger, H. (2003) IR5878: A 96-Hour Static Acute 

Toxicity Test with the Bluegill (Lepomis macrochirus): Final Report. Project 

Number: 544A/111. Unpublished study prepared by Wildlife International, Ltd. 38 

p. 

46578951 Palmer, S.; Kendall, T.; Krueger, H. (2002) IR5878: A 96-Hour Statice Acute 

Toxicity Test with the Sheepshead Minnow (Cyprinodon varigatus): Final Report. 

Project Number: 544A/109. Unpublished study prepared by Wildlife International, 

Ltd. 37 p. 

46578955 Sutherland, C.; Kendall, T.; Krueger, H. (2003) IR5878: A 96-Hour Static Acute 

Toxicity Test with the Crayfish (Procambarus clarkii): Final Report. Project 

Number: 544A/124. Unpublished study prepared by Wildlife International, Ltd. 49 

p. 

850.1300 Daphnid chronic toxicity test 

46578956 Palmer, S.; Thomas, S.; Kendall, T.; et al. (2003) IR5878: A Semi-Static Life-Cycle 

Toxicity Test with the Cladoceran (Daphnia magna): Final Report. Project Number: 

544A/123. Unpublished study prepared by Wildlife International, Ltd. 57 p. 

850.1350 Mysid chronic toxicity test 

46578954 Blankinship, A.; Kendall, T.; Krueger, H. (2003) IR5878: A Flow-Through LifeCycle Toxicity Test with the Saltwater Mysid (Mysidopsis bahia): Final Report. 

Project Number: 544A/112. Unpublished study prepared by Wildlife International, 

Ltd. 70 p. 

850.1400 Fish early-life stage toxicity test 
68 

46578953 Palmer, S.; Kendall, T.; Krueger, H. (2003) IR5878: An Early Life-Stage Toxicity 

Test with the Fathead Minnow (Pimephales promelas): Final Report. Project 

Number: 544A/110. Unpublished study prepared by Wildlife International, Ltd. 71 

p. 

850.1730 Fish BCF 

46588507 Dijk, A. (2004) Bioconcentration: Flow-Through Fish Test with IR5878 in Bluegill 

Sunfish (Lepomis macrochirus). Project Number: 849257, WD00612/000. 

Unpublished study prepared by RCC Umweltchemie Ag. 68 p. 

850.3020 Honey bee acute contact toxicity 

46219046 Schmitzer, S. (2003) Laboratory Testing for Toxicity (Acute Contact and Oral 

LD50) of IR5878 on Honey Bees (Apis mellifera L.): Final Report. Project Number: 

1, 8225036. Unpublished study prepared by Institut fuer Biologische Analytik und 

Consulting IBACON Gmbh. 41 p. 

850.4100 Terrestrial plant toxicity, Tier 1 (seeding emergence) 

46578941 Porch, J.; Krueger, H.; Martin, K. (2003) IR5878 50WG: A Toxicity Test to 

Determine the Effects on Seedling Emergence of Ten Species of Plants: Final 

Report. Project Number: 544/110. Unpublished study prepared by Wildlife 

International, Ltd. 107 p. 

46710802 Porch, J.; Krueger, H.; Krip, W. (2005) IR5878 50WG: A Toxicity Test to 

Determine the Effects on Seedling Emergence of Tomato: Final Report. Project 

Number: 544/113. Unpublished study prepared by Wildlife International, Ltd. 39 p. 

850.4150 Terrestrial plant toxicity, Tier 1 (vegetative vigor) 

46578942 Porch, J.; Krueger, H. (2003) IR5878 50WG: A Toxicity Test to Determine the 

Effects on Vegetative Vigour of Ten Species of Plants: Final Report. Project 

Number: 544/111. Unpublished study prepared by Wildlife International, Ltd. 146 

p. 

46710801 Porch, J.; Krip, W.; Krueger, H. (2005) IR5878WG: A Toxicity Test to Determine 

the Effects on Vegetative Vigour of Two Species of Plants: Final Report. Project 

Number: 544/114. Unpublished study prepared by Wildlife International, Ltd. 65 p. 

850.4225 Seedling emergence, Tier II 

46578941 Porch, J.; Krueger, H.; Martin, K. (2003) IR5878 50WG: A Toxicity Test to 

Determine the Effects on Seedling Emergence of Ten Species of Plants: Final 

Report. Project Number: 544/110. Unpublished study prepared by Wildlife 

International, Ltd. 107 p. 

46710802 Porch, J.; Krueger, H.; Krip, W. (2005) IR5878 50WG: A Toxicity Test to 

Determine the Effects on Seedling Emergence of Tomato: Final Report. Project 

Number: 544/113. Unpublished study prepared by Wildlife International, Ltd. 39 p. 

850.4250 Vegetative vigor, Tier II 

46578942 Porch, J.; Krueger, H. (2003) IR5878 50WG: A Toxicity Test to Determine the 

Effects on Vegetative Vigour of Ten Species of Plants: Final Report. Project 

Number: 544/111. Unpublished study prepared by Wildlife International, Ltd. 146 

p. 
69 

46710801 Porch, J.; Krip, W.; Krueger, H. (2005) IR5878WG: A Toxicity Test to Determine 

the Effects on Vegetative Vigour of Two Species of Plants: Final Report. Project 

Number: 544/114. Unpublished study prepared by Wildlife International, Ltd. 65 p. 

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

46578939 Desjardins, D.; Kendall, T.; Krueger, H. (2003) IR5878 50WG Alone: A 7-Day 

Toxicity Test with Duckweed (Lemna gibba G3): Final Report. Project Number: 

544A/120. Unpublished study prepared by Wildlife International, Ltd. 44 p. 

46578940 Desjardins, D.; Kendall, T.; Krueger, H. (2004) IR5878 50WG: A 7-Day Toxicity 

Test with Duckweed (Lemna gibba G3): Final Report. Project Number: 544A/114. 

Unpublished study prepared by Wildlife International, Ltd. 45 p. 

850.5400 Algal toxicity, Tiers 1 and II 

46578931 Desjardins, D.; Kendell, T.; Krueger, H. (2003) IR5878 50WG Alone: A 96-Hour 

Toxicity Test with the Freshwater Alga (Selejastrum capricornutum): Final Report. 

Project Number: 544A/121. Unpublished study prepared by Wildlife International, 

Ltd. 50 p. 

46578932 Desjardins, D.; Kendall, T.; Krueger, H. (2003) IR5878 50WG Alone: A 96-Hour 

Toxicity Test with the Freshwater Diatom (Navicula pelliculosa): Final Report. 

Project Number: 544A/119. Unpublished study prepared by Wildlife International, 

Ltd. 50 p. 

46578933 Desjardins, D.; Kendell, T.; Krueger, H. (2003) IR5878 50WG Alone: A 96-Hour 

Toxicity Test with the Marine Diatom (Skeletonema costatum). Project Number: 

544A/122. Unpublished study prepared by Wildlife International, Ltd. 53 p. 

46578934 Desjardins, D.; Kendell, T.; Krueger, H. (2003) IR5878 50WG: A 96-Hour Toxicity 

Test with the Freshwater Alga (Selenastrum capricornutum): Final Report. Project 

Number: 544A/116. Unpublished study prepared by Wildlife International, Ltd. 54 

p. 

46578935 Desjardins, D.; Kendall, T.; Krueger, H. (2003) IR5878 50WG: A 96-Hour Toxicity 

Test with the Freshwater Diatom (Navicula pelliculosa): Final Report. Project 

Number: 544A/115. Unpublished study prepared by Wildlife International, Ltd. 53 

p. 

46578936 Desjardins, D.; Kendell, T.; Krueger, H. (2003) IR5878 50WG: A 96-Hour Toxicity 

Test with the Marine Diatom (Skeletonema costatum): Final Report. Project 

Number: 544A/117A. Unpublished study prepared by Wildlife International, Ltd. 

53 p. 

46578937 Desjardins, D.; Kendall, T.; Krueger, H. (2003) IR5878 50WG: A 96-Hour Toxicity 

Test with the Freshwater Alga (Anamaena flos-aquae): Final Report. Project 

Number: 544A/113. Unpublished study prepared by Wildlife International, Ltd. 51 

p. 

46578938 Desjardins, D.; Kendall, T.; Krueger, H. (2003) IR5878 50WG Alone: A 96-Hour 

Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Final Report. 

Project Number: 544A/118. Unpublished study prepared by Wildlife International, 

Ltd. 55 p. 

870.1100 Acute oral toxicity 
70 

46219019 Yu, P. (1999) Acute Oral Toxicity Study in Rats Treated with the Test Article 

IR5878. Project Number: 990496. Unpublished study prepared by Istituto Di 

Recerche Biomediche (RBM) "Antoine Marxer". 34 p. 

46578918 Ott, M. (2003) IR7863: Acute Oral Toxicity Study in Rats. Project Number: 

A2/05/08/05, 850107. Unpublished study prepared by RCC Ltd. 20 p. 

870.1300 Acute inhalation toxicity 

46219066 Decker, U.; Knuppe, C.; Ullrich, A. (2003) IR5878 50WG Alone: 4-Hour Acute 

Inhalation Toxicity Study in Rats: Final Report. Project Number: 847655, 904994. 

Unpublished study prepared by RCC Ltd. 85 p. 

46219067 Decker, U.; Knuppe, C.; Ullrich, A. (2003) IR5878 50WG: 4-Hour Acute Inhalation 

Toxicity Study in Rats: (Technical Trials Preceding a Proposed 4-Hour Acute 

Inhalation Toxicity Study in Rats): Final Report. Project Number: 847122. 

Unpublished study prepared by RCC Ltd. 37 p. 

46578990 Decker, U.; Knuppe, C.; Ullrich, A. (2004) IR5878 0.5 GR: 4-Hour Acute 

Inhalation Toxicity Study in Rats: Final Report. Project Number: 849646, 

A3/07/01/20. Unpublished study prepared by RCC Umweltchemie Ag. 86 p. 

870.4300 Combined chronic toxicity/carcinogenicity 

46578913 Webley, L. (2004) IR5878: Combined Carcinogenicity and Toxicity Study By 

Dietary Administration to Han Wistar Rats for 104 Weeks. Project Number: 

A2/05/05/02, AGR/131/033063, AGR/131. Unpublished study prepared by 

Huntingdon Life Sciences, Ltd. 2241 p. 
71 

Appendix A. Supplemental Environmental Fate Information 

Table A1. Summary of other environmental fate and transport properties of 

orthosulfamuron. 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Hydrolysis6

Half-life, linear regression1

: 

pH 7 at 25o

C: 24.4 days 

pH 9 at 25o

C: 228 days 

pH 4 at 50o

C: 0.02 days 

pH 7 at 50o

C: 1.5 days 

pH 9 at 50o

C: 8.0 days 

MRID 46219015 

(supplemental) 

Values may be used in risk assessment. 

Sterility not confirmed. Sterile buffer 

solution and glassware were used in 

study. Degradate concentrations 

increased over duration of study. 

Half-life, linear regression1: 

pH 4 at 50o

C: 0.02 days 

pH 7 at 50o

C: 1.2 days 

pH 9 at 50o

C: 8.6 days 

MRID 46219016 

(supplemental) 

May be used quantitatively. Study was 

conducted at 50o

C and sterility was not 

confirmed. Sterile buffer solution and 

glassware were used in study. 

Atmospheric 

Degradation 

Half-life: 

0.049 days (estimated) 

Estimated Using 

EPIWeb Version 4.0 

see Appendix A. 

Not likely to undergo long range 

transport in vapor phase.3

Aqueous 

Photolysis 

Stable MRID 46588509 

(supplemental) 

Study had many deficiencies but was 

adequate to show that photolysis was 

not a significant degradation pathway. 

Half-lives that were not adjusted for 

environmental conditions were 85-90 

days. Intensity of artificial light was not 

compared to natural sunlight. Study 

duration was 7 days with 94% of the 

compound remaining. The sterility was 

not confirmed, temperature range was 

25±5o

C, and pH was not reported. 

Soil Photolysis No data submitted Not applicable None 

Aerobic Soil 

Metabolism 

No data submitted Not applicable None 

Anaerobic Soil 

Metabolism 

No data submitted Not applicable None 
72 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Aerobic Aquatic 

Metabolism 4

Half-life, linear regression1, at 20oC: 

Parent Only 

40.6 and 36.3 (AR, loam soil pH 6.9-

7.25, water pH 7.8-6.81) 

24.1 and 21.3 days (CA, clay soil pH 

6.0-6.97, water pH 7.7-7.03) 

Parent+ Unextracted residues: 

70.5 and 59.2 (AR, loam soil pH 6.9-

7.25, water pH 7.8-6.81) 

65.4 and 30.3 days (CA, clay soil pH 

6.0-6.97, water pH 7.7-7.03) 

MRID 46219017 

(supplemental) 

Some values were estimated using a 

subset of data. The values shown are 

for different rings labeled. Unextracted 

residues ranged from not detected to 

33% applied radioactivity. Reasonable 

attempt to extract all residues was not 

made. Soil used instead of sediment. 

Anaerobic 

Aquatic 

Metabolism 

Half-life, linear regression1, at 20oC: 

Parent Only: 

80 and 89 days (AR water-loam soil 

pH 6.9-7.45, water pH 7.8-7.44) 

41 and 41 days (CA pond-water clay 

soil pH 6.0-6.72, water pH 7.7-6.82) 

Parent+Unextracted Residues: 

142 and 217 days (AR water-loam 

soil pH 6.9-7.45, water pH 7.8-7.44) 

88 and 161 days (CA pond-water clay 

soil pH 6.0-6.72, water pH 7.7-6.82) 

MRID 46578967 

(supplemental) 

Values may be used in risk assessment 

as these values are the best available 

information; however, data are still 

needed to fully understand degradation 

of orthosulfamuron in anaerobic aquatic 

environments. The values shown are for 

different rings labeled.5

Sorption 

coefficients 

Solid-water distribution Coefficient, 

Kd in L/kg 

6.1, sandy loam, pH 6.3, 1.13%OC 

8.6, silt loam, pH 5.7, 2.03%OC 

6.3, silt loam, pH 6.8, 1.00%OC 

6.1, clay loam, pH 6.1, 2.60% OC 

Organic-carbon normalized 

distribution coefficient, KOC in L/kgOC: 

532, sandy loam, pH 6.29, 1.13%OC 

425, silt loam, pH 5.71, 2.03%OC 

626, silt loam, pH 6.78, 1.00%OC 

266, clay loam, pH 6.11, 2.60% OC 

MRID 46219074 

(supplemental) 

Does not fulfill guideline. Soils from 

Italy used and information was not 

provided on whether the soils are 

representative of U.S. Soils used for rice 

production. Only four different 

isotherm data points were included 

when five are required. None of the 

test soils had an organic matter content 

less than 1%. Material balance only 

reported for high-dose soils. 
73 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Solid-water distribution Coefficient, 

Kd in L/kg 

2.5, sandy loam, pH 6.5, 1.04% OC 

7.5, sandy loam, pH 5.6, 0.35% OC 

3.2, sand, pH 4.70, 1.03% OC 

20.7, clay loam, pH 5.4, 3.01% OC 

2.0, silt loam, pH 7.5, 0.92% OC 

7.0, loam, pH 7.4, 1.8% OC 

Organic-carbon normalized 

distribution coefficient, KOC in L/kgOC: 

238, sandy loam, pH 6.5, 1.04%OC 

2145, sandy loam, pH 5.6, 0.35% OC 

307, sand, pH 4.7, 1.03% OC 

687, clay loam, pH 5.4, 3.01% OC 

215, silt loam, pH 7.5, 0.92% OC 

389, loam, pH 7.4, 1.8% OC 

MRID 46578971 

(supplemental) 

Material balance and stability only 

determined in supplementary 

experiment with soil and test solution. 

The recovery of radioactivity in all 

systems was near 100%. The 

coefficient of variation(CV) for all Kd

values was 76%, 98% for all KOC

values, when the outlying high Kd and 

KOC are removed for the soil with an OC 

content of 0.35%, the CV was 81% for 

Kd values and 42% for KOC values. 

Aged Column 

Leaching 

Orthosulfamuron not observed in 

leachate but was observed in Segment 

D (21 cm depth). DBS-acid, DBS 

amide, DB amine, o-desmethyl 

orthosulfamuron, DOP urea, DOP 

amine, and o-desmethyl DOP urea 

were all detected at lower segments as 

well. 

MRID 46219018 

(acceptable) 

A column was prepared with Arkansas 

soil/water, orthosulfamuron was added 

and the column was aged for 69 days. 

pH in water was 6.9 and 6.2 in CaCl2

solution. 

Soil Column 

Leaching 

Orthosulfamuron was the only 

compound found in leachate and 

lower soil segments. DOP urea was 

found in top 0-25 cm of soil and DOP 

amine was not detected in one soil but 

was detected in another. Movement 

through the column indicates that it 

has the potential to move through soil 

in environment. 

MRID 46578968 

(supplemental) 

Only one ring was labeled. Arkansas 

sandy loam soil and North Dakota sand 

soil. 

Aquatic Field 

Dissipation 

Dissipation Half-life2, linear 

regression1

Arkansas Site: 

4.1 days (soil) 

6.2 days (sediment) 

6.4 days (water) 

California Site: 

2.3 days (soil) 

4.3 days (sediment) 

Not calculated (water) 

MRID 46578985 

(supplemental) 

Bareground plots were flooded 1-2 days 

after application of 0.335 lbs a.i./A. 

Storage stability data could not 

demonstrate stability of test compound 

for the maximum storage interval. 

Recoveries were low for DOP urea and 

DBS acid. Associated ECM and ILV 

are not available for soil and water. 

Therefore, these values may 

underestimate the field half-lives and 

should be considered with an 

understanding of the data limitations. 
74 

Parameter Value(s) and Units Source (Study 

Classification)

Comments 

Steady State 

Bioconcentration 

Factor 

Measured at 135.2 μg/L at 22-23oC in 

Bluegill Sunfish (Lepomis 

macrochirus): 

0.29 L/kg wet weight, edible tissue 

0.34 L/kg wet weight, nonedible 

tissue 

32 L/kg wet weight, whole fish 

16 – 29 L/kg-lipid 

Measured at 1391-1550 μg/L at 22-

23o

C: 

0.72 L/kg wet weight, edible tissue 

1.14 L/kg wet weight, nonedible 

tissue 

0.97 L/kg wet weight, whole fish 

52-68 L-kg-lipid 

46588507 

(acceptable) 

pH values ranged from 7.5-8.0. TOC in 

treated aquaria ranged from 33-41 mg/L. 

Calculations are an average of 5 

sampling intervals over 14 days of 

exposure. It is uncertain whether BCF 

values were still increasing at the first 

sampling (4 day) interval. A steady 

increase in concentration was not 

observed over time. 

Environmental 

Chemistry 

Method: Water 

None submitted NA None 

Environmental 

Chemistry 

Method: Soil 

and Sediment 

None submitted NA None 

Abbreviations: ECM=Environmental Chemistry Method; ILV=independent laboratory Validation 

1

Degradation kinetics were calculated using the single first order decay equation using either nonlinear regression of 

non-transformed data or linear regression of natural log-transformed data. 

2

 The value may reflect both dissipation and degradation processes. 

3

 The minutes of the Scientific Advisory Panel examining issues related to persistent, bioaccumulative, and toxics 

states, “To protect against long range transport, a two-day degradation half life in air is used internationally in 

regulations that identify persistent chemicals.” (USEPA, 2009b) 

4

 MRID 46588508 is an aerobic aquatic metabolism study that was conducted outdoors and samples were exposed to 

sunlight and fluctuating temperatures. A poor material balance was obtained. The study is considered unacceptable. 5

 Unextracted residues ranged from not detected to 43% applied radioactivity. Reasonable attempt to extract all 

residues was not made. The differences in half-lives for the different radiolabeled rings for parent+unextracted 

residues suggests that not all of the unextracted residues are the parent; however, it is not known what fraction is and 

is not the parent. Hydrolysis rates range with pH and pH range represented is very narrow. The values shown are 

not representative of the pH range in rice paddies and natural environments (pH 4-10). Microbial biomass was not 

determined in sediment or water. Limit of quantitation not reported. A soil instead of a sediment was used in the 

study. Water and sediments were not fully characterized and collection procedures (sampling depth, temperature, 

dissolved oxygen content, and microbial biomass) were not reported. 

6

 MRID 46578970 is unacceptable because no material balance was conducted 
75 

(1) 11.53±0.70 

(2) 9.57±0.50 

(3) 3.52 ±0.40 and -3.39±0.70 

(4) 0.73±0.50 

(5) -1.37±0.70 

Figure A2. Structure and associated dissociation constants predicted using Advanced 

Chemistry Development, I-Labe Web Service. 

A1. Sorption Coefficients and Mobility 

Table A1 summarizes the sorption coefficients measured for orthosulfamuron. Freundlich 

Distribution Coefficients (KF) values from ten soils range from 2.0 to 20 L/kg (MRID 46219074; 

46578971). Freundlich exponents ranged from 0.75 to 1.2 and sorption was influenced by 

concentration in a few soils. As orthosuflamuron has several pKa values, its affinity to organic 

materials and other materials in soils and sediment are expected to change with pH; however, 

available data do not support this. Limited data are available to understand the influence of pH 

on sorption and thus a full analysis of the influence of various soil/sediment consituents cannot 

be fully understood. Nevertheless, available data indicate that the coefficient of variation (CV) 

for KOC (115%) is larger than that for KF (79%) across all ten soils studied due to one outlying 

high KOC value (2,330 L/kgOC). Upon omission of the outlying KOC value from the remaining 

nine KOC values (range of 217 – 653 L/kgOC), the CV for KOC (42%) is less than that for KF

(86%), which is expected when organic carbon content in soil correlates with KF values. The 

character of the organic material (which was present at a very low level, at 0.35% organic 

carbon) in the outlying sorption coefficient could explain the higher measured value. KF values 

correlated with the clay content of soils (p<0.05), but not soil pH (p>0.05; pH range 4.7 to 8.0). 

Table A1. Summary of measured sorption coefficients for orthosulfamuron at 20o

C. 

Soil, 

% OC

pH

Kd

(L/kgsoil)a

KOC

(L/kg-OC)b

KF

(L/kg-soil)-

1/n)

 c

1/ne KFOC

(L/kg-OC)-1/n)

 c

Ceq Ranged

 (mg/L)

MRID 46219074 

B-1 Sandy 

Loam, 

1.13%

pH 6.29 

6.01 532 3.76 0.751 283 0.020 – 3.889 
76 

Soil, 

% OC

pH

Kd

(L/kgsoil)a

KOC

(L/kg-OC)b

KF

(L/kg-soil)-

1/n)

 c

1/ne KFOC

(L/kg-OC)-1/n)

 c

Ceq Ranged

 (mg/L)

G-2 

Silt Loam 

2.03%

 pH 5.71 

8.62 425 6.62 0.856 326 0.017 – 3.196 

M-2 

Silt Loam 

1.00% 

pH 6.78 

6.26 626 5.47 0.920 547 0.024 – 2.861 

VM-1 

Clay loam 

2.30%

pH 7.98 

6.11 266 5.72 0.955 249 0.023 – 2.821 

MRID 46578971 

Ark-1 

Sandy 

Loam 

1.04% 

pH 6.50 

2.48 238 2.37 0.974 228 0.033 – 3.303 

Ark-2 

Sandy 

Loam 

0.35% 

pH 5.66 

7.51 2145 8.17 1.062 2330 0.023 - 1.885 

Benson 

Sand 

1.03% 

pH 4.70 

3.17 307 3.61 1.152 350 0.033 - 2.695 

M-CL Clay 

Loam 

3.01% 

pH 5.37 

20.68 687 19.7 0.980 653 0.01 – 1.147 

PC-1 Silt 

Loam 

0.92% 

pH 7.50 

1.98 215 2.0 1.019 217 0.039 – 3.669 

Pratt Loam 

1.80% 

pH 7.40 

6.99 389 6.86 0.990 381 0.02 – 2.192 

a

 Kd –Solid-water distribution coefficient

b

 KOC = regressed Kd *100/% OC c

KF - Freundlich adsorption coefficients and the Freundlich exponent (1/n) 

d

 KFOC = KF*100/%OC e

 Ceq range is the range of orthosulfamuron concentrations in water at equilibrium. 

In column leaching studies, orthosulfamuron, DBS-acid, DBS amide, DB amine, o-desmethyl 

orthosulfamuron, DOP urea, DOP amine, and o-desmethyl DOP urea were all detected in lower 

soil segments, demonstrating that movement through soil layers is possible for these compounds 

(MRIDs 46578968 46219018). Column leaching studies of aged orthosulfamuron indicated that 

some degradates (DBS acid, DBS amide, and o-desmethyl orthosulfamuron) are capable of 

greater mobility than the parent and are more likely to leach to ground water (MRID 46219018). 
77 

Both orthosulfamuron and its degradates have the potential to leach to groundwater. 

A2. Degradation 

Abiotic Degradation 

Orthosulfamuron hydrolyzed with half-lives of 24.4 and 228 days at 25°C in pH 7 and pH 9 

buffered solutions, respectively (MRID 46219015, 46578970). The half-lives at pH 4 or 5 are 

uncertain as data are not available at 25o

C. The half-life of 0.02 days at 50oC and pH 4 suggests 

that hydrolysis at pH 5 will be rapid (MRID 46219016). Major identified hydrolysis degradates 

were DBS acid, DB amine, DOP amine, and DOP urea. 

Ninety-four percent of orthosulfamuron remained when irradiated continuously under a filtered 

xenon lamp for 6.92 days at 25oC in a pH 9 buffered solution (MRID 46588509). As 94% was 

remaining after seven days, it is likely that aqueous photolysis will only play a minor role in the 

transformation of orthosuflamuron in the environment. No major photodegradates were 

detected. 

Biodegradation 

The aerobic aquatic metabolism of orthosulfamuron was studied using pond water-sediment 

systems from Arkansas and California (MRID 46219017). Half-lives were calculated by 

assuming unextracted residues were and were not the parent compound because multiple solvent 

systems were not employed in extraction and non-extracted residues reached 11-33% of 

applied.29 Degradation occurred more rapidly under aerobic conditions as compared to 

anaerobic conditions. Total system half-lives for parent and unextracted residues in the Arkansas 

system30 were 70.5 and 59.2 days for pyrimidinyl- and phenyl-labeled orthosulfamuron, 

respectively. Similar to the anaerobic aquatic metabolism study, degradation appeared to occur 

more rapidly in the California pond-sediment system31; total system half-lives for parent and 

unextracted residues were 65.4 and 30.3 days for pyrimidinyl- and phenyl-labeled 

orthosulfamuron, respectively. Total sytem half-lives calculated with extracted parent compound 

alone were 40.6 and 36.3 days for the pyrimidinyl and phenyl labels in Arkansas, respectively, 

and 24.1 and 21.3 days for the pyrimidinyl and phenyl labels in California, respectively. The 

major identified degradates were DBS acid and DOP urea. 

An anaerobic aquatic metabolism study was conducted for orthosulfamuron using a pond waterloam sediment system from Arkansas for 180 days and a pond water-clay sediment system from 

California for 150 days (MRID 46578967). Half-lives were calculated by counting nonextracted residues as parent compound because 1) a portion of unextracted residues could be the 

parent compound, 2) a reasonable attempt was not made to demonstrate that the extraction 

 

29 Unextracted residues increased throughout the study but did not increase to above 10% until less than 50% of the 

parent was remaining. This provides some evidence that not all of the unextracted residues are the parent; however, 

it is stil uncertain whether a portion of the unextracted residues were the parent compound. 

30 The Arkansas test system consisted of water from a pond and a loam sediment. The pH of the water was 7.8 and 

the pH of sediment was 6.2-6.9. 

31 The California test system consisted ofr pond water and clay sediment. The pH of the water was 7.7 and pH in 

sediment porewater was 5.6-6.0. 
78 

procedure removed all possible material, and 3) unextracted residues made up a large portion of 

measured radioactivity.32 Total system half-lives of parent and unextracted residues in the 

Arkansas sediment were 217 and 142 days for pyrimidinyl- and phenyl-labeled orthosulfamuron, 

respectively. Degradation occurred more rapidly in the California sediment; total system halflives for the parent and unextracted residues were 161 and 88 days for pyrimidinyl- and phenyllabeled orthosulfamuron, respectively. Total system half-lives calculated with extracted parent 

compound alone were 89 and 80 days for the pyrimidinyl and phenyl labels in Arkansas, 

respectively, and 41 days for both labels in California. Calculated half-lives for the parent alone 

are very similar for the (41 days in California versus 80 and 89 days in Arkansas) while halflives for different labels were different when unextracted residues were included in the 

calculation (88 and161 days for California versus 142 and 217 days for Arkansas). This suggests 

that the unextracted residues were not the parent; however, it is possible that some portion of the 

unextracted residues were the parent. The major identified degradates were DBS acid, odesmethyl orthosulfamuron, and DOP urea. 

A3. Field Studies 

A single aquatic field dissipation study was conducted for orthosulfamuron using a bare ground 

plot of silt loam soil (pH 6.7) in Arkansas and a bare ground plot of silty clay loam soil (pH 7.7) 

in California (MRID 46578985). The results must be considered only as supplementary 

information as recoveries from field spikes were low33 and validated environmental chemistry 

methods were not provided.34 Measured concentrations could underestimate actual half-lives 

and concentrations. The plots were flooded with water 1–2 days following the application of 

orthosulfamuron to approximate the timing of herbicide application to rice. Soil samples (0-60 

cm depth) were collected through 550-553 days post-treatment. Water and the underlying soil 

(“sediment”; 0-5 cm depth) samples were collected from 3 days to 2 months post-treatment. At 

the Arkansas test site, orthosulfamuron dissipated in the soil (0-15 cm depth), sediment (0-5 cm 

depth), and water with half-lives of 4.1 days, 6.2 days, and 6.4 days, respectively. At the 

California site, orthosulfamuron dissipated in the soil (0-15 cm depth) and sediment (0-5 cm 

depth) with half-lives of 2.3 days and 4.3 days, respectively. No half-life was calculated for the 

water phase because the chemical was not detected in the water. 

Both test sites were analyzed for DOP urea, DBS acid, and o-desmethyl orthosulfamuron. Odesmethyl orthosulfamuron was below detection limits in all samples from both sites. At the 

Arkansas site, DOP urea and DBS acid were major degradates in the soil and sediment; DBS 

acid was the major degradate in water. At the California site, DOP urea was the major degradate 

in soil and sediment; no major degradates were detected in water. 

 

32 In the California system, unextracted residues were an average of not detected, 6.5, 13.2, 14.0, 17.7, 34.0, and 

43.2 percent at 0, 8, 15, 35, 59, 100, and 150 days. In the Arkansas system, unextracted residues were an average of 

not detected, 9.8, 10.1, 7.0, 11.7, 18.6, and 24.0 percent at 0, 8, 15, 35, 59, 10, and 150 days respectively. 

33 Recoveries from field spiked soil samples for orthosulfamuron, DOP urea, and DBS acid ranged from 47-70%, 

58-78%, and 9-34%, respectively. Recoveries from field spiked sediment samples for orthosulfamuron, DOP urea, 

and DBS acid ranged from 28-106%, 45-82%, and 27-36%, respectively. Recoveries from field spiked water 

samples for orthosulfamuron, DOP urea, and DBS acid ranged from 63-83%, 87-123%, and 51-96%, respectively. 

34 Independent laboratory validation studies were conducted for extraction of IR7825, IR8181, and IR7863 from 

soil and water that were different than those used in the study. 
79 

A4. Bioconcentration 

A flow-through bioconcentration study of bluegill sunfish (Lepomis macrochirus) exposed to 

orthosulfamuron in pH 7.5-8.0 water for 14 days indicates that the compound does not 

bioconcentrate. Steady State Bioconcentration factors (BCF) were 0.29, 0.34, and 0.32 L/kg wet 

weight for edible, non-edible, and whole fish tissues, respectively, in low-dose samples (142 

μg/L) and 0.72, 1.14, and 0.97 L/kg wet weight for edible, non-edible, and whole fish tissues, 

respectively, in high-dose samples (1420 μg/L). BCF values less than 1,000 are not expected to 

bioconcentrate significantly [64 Fed. Reg. 60194-60204 (November 4, 1999)]. 

A5. Transformation Products 

The transformation products resulting from the environmental degradation processes of 

orthosulfamuron are: 

• 2-dimethylcarbamoylphenyl sulfamic acid (DBS acid; IR7863; S1); 

• 2-sulfamoylamino-N,N-dimethylbenzamide (DBS amide; S2); 

• 2-amino-N,N-dimethylbenzamide (DB amine; S4); 

• 1-(4-hydroxy-6-methoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl) 

phenylsulfamoyl]urea (o-desmethyl orthosulfamuron; IR8181; S9); 

• N-(4,6-dimethoxypyrimidin-2-yl)urea (DOP urea; IR7825; S12); 

• 4,6-dimethoxypyrimidin-2-yl amine (DOP amine; S13); and 

• N-(4-hydroxy-6-methoxypyrimidin-2-yl)urea (o-desmethyl DOP urea; S15). 

Two other degradation products S5 and S11 are composed of multiple unresolved compounds. 

DBS acid (S1), DB amine (S4), o-desmethyl orthosulfamuron (S9), and DOP urea (S12) were 

the major degradates identified at a maximum of 62%, 13%, 19%, and 111% of the applied, 

respectively, detected at 7, 176, 100, and 7 days after treatment, respectively. Peak detections of 

these degradates occurred at up to 100-186 days after application. Chemical structures of these 

degradation products are shown in Appendix J.

The main degradation pathway of orthosulfamuron appears to be the hydrolytic cleavage of the 

sulfamoylurea linkage to give DOP urea (S12) and DBS acid (S1). Another degradation 

pathway is the demethylation of orthosulfamuron to its o-desmethyl degradate (S9), which may 

also degrade to DBS acid. Orthosulfamuron and DBS acid may hydrolyze to form DB amine 

(S4). The maximum amounts of these degradation products observed in hydrolysis, aerobic 

aquatic metabolism, anaerobic aquatic metabolism, and aquatic field dissipation studies are 

summarized in Appendix J. No degradation products were detected in the photolysis study. 

Degradation products were not analyzed for in the hydrolysis study at pH 5. 

Table A2. Summary of Storage Stability Studies 

Parameter Value(s) and Units Source Comments 

Storage Stability DBS acid shown to be stable in CA and 

AR soil and sediment when stored in the 

dark at 20o

C for 355 days. 

46578977 None 
80 

Parameter Value(s) and Units Source Comments 

DBS acid and DP amine shown to be 

stable in surface water (collected from a 

pond in Italy) stored in the dark below 

20o

C for 362 days. 

46578978 None 

DOP urea shown to be stable in surface 

water (collected from a pond in Italy) 

stored in the dark below 20o

C for 388 

days. 

46578979 None 

DOP urea shown to be stable in soil 

(collected from an AR and CA site) and 

sediment (from an untreated rice field in 

Italy) stored in the dark below 20o

C for 

386 days. 

46578980 None 

A6. Results from AOPwin 

SMILES : c2cccc(c2NS(=O)(=O)NC(=O)(Nc1nc(cc(n1)OC)OC))C(=O)N(C)C 

CHEM : 

MOL FOR: C16 H20 N6 O6 S1 

MOL WT : 424.43 

------------------- SUMMARY (AOP v1.92): HYDROXYL RADICALS (25 deg C) -------- 

Hydrogen Abstraction = 2.7744 E-12 cm3/molecule-sec 

**Reaction with N, S and -OH = 16.0000 E-12 cm3/molecule-sec 

Addition to Triple Bonds = 0.0000 E-12 cm3/molecule-sec 

Addition to Olefinic Bonds = 0.0000 E-12 cm3/molecule-sec 

**Addition to Aromatic Rings = 200.0000 E-12 cm3/molecule-sec 

Addition to Fused Rings = 0.0000 E-12 cm3/molecule-sec 

 OVERALL OH Rate Constant = 218.7744 E-12 cm3/molecule-sec 

 HALF-LIFE = 0.049 Days (12-hr day; 1.5E6 OH/cm3) 

 HALF-LIFE = 0.587 Hrs 

........................ ** Designates Estimation(s) Using ASSUMED Value(s) 

------------------- SUMMARY (AOP v1.91): OZONE REACTION (25 deg C) ----------- 

 ****** NO OZONE REACTION ESTIMATION ****** 

 (ONLY Olefins and Acetylenes are Estimated) 

Experimental Database: NO Structure Matches 

A7. Estimated KOC values for Degradates: 
81 

Table A3. Summary of Estimated KOC values for Degradates (KOCwin v2.00). 

Degradate Name KOC estimate from MCI 

(L/kg) 

KOC estimate from Log KOW

(L/kg-OC) 

DBS acid 10 0.08692 

DB amine 10 7.4 

DOP Amine 10 86.94 

DOP urea 10 53.01 

DBS Amide 12.09 2.919 

o-desmethyl 

orthosulfamuron 

10 13.23 

Orthosulfamuron 10 22.28 

DBS Acid

SMILES : CN(C)C(=O)c1ccccc1NS(=O)(=O)O 

CHEM : 

MOL FOR: C9 H12 N2 O4 S1 

MOL WT : 244.27 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 7.310 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 4.4107 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.5225 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 1 Miscellaneous S(=O) group .......... : -1.2980 

 Corrected Log Koc .................................. : 0.5600 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : -3.35 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : -0.9279 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.0216 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 1 Miscellaneous S(=O) group .......... : 0.1614 

 Corrected Log Koc .................................. : -1.0609 

 Estimated Koc: 0.08692 L/kg <=========== 

DB amine

SMILES : CN(C)C(=O)c1ccccc1N 

CHEM : 

MOL FOR: C9 H12 N2 O1 

MOL WT : 164.21 

--------------------------- KOCWIN v2.00 Results --------------------------- 
82 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 5.626 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 3.5326 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.5225 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 Corrected Log Koc .................................. : 0.9799 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : 0.43 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.1629 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.0216 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 Corrected Log Koc .................................. : 0.8685 

 Estimated Koc: 7.387 L/kg <=========== 

 

DOP Amine

SMILES : COc1cc(OC)nc(N)n1 

CHEM : 

MOL FOR: C6 H9 N3 O2 

MOL WT : 155.16 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 5.258 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 3.3406 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.5225 

 2 Ether, aromatic (-C-O-C-) ........... : -1.3582 

 1 Aromatic ring with 2 nitrogens ....... : -0.5964 

 Corrected Log Koc .................................. : 0.8635 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : 0.95 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.4506 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.0216 

 2 Ether, aromatic (-C-O-C-) ........... : 0.1118 

 1 Aromatic ring with 2 nitrogens ....... : 0.3984 

 Corrected Log Koc .................................. : 1.9392 
83 

 Estimated Koc: 86.94 L/kg <=========== 

DOP Urea

SMILES : COc1cc(OC)nc(NC(=O)(N))n1 

CHEM : 

MOL FOR: C7 H10 N4 O3 

MOL WT : 198.18 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 6.651 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 4.0672 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.5225 

 2 Ether, aromatic (-C-O-C-) ........... : -1.3582 

 1 Urea (N-CO-N) ....................... : -1.0038 

 1 Aromatic ring with 2 nitrogens ....... : -0.5964 

 Corrected Log Koc .................................. : 0.5863 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : 0.58 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.2459 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.0216 

 2 Ether, aromatic (-C-O-C-) ........... : 0.1118 

 1 Urea (N-CO-N) ....................... : -0.0102 

 1 Aromatic ring with 2 nitrogens ....... : 0.3984 

 Corrected Log Koc .................................. : 1.7243 

 Estimated Koc: 53.01 L/kg <=========== 

 

SMILES : CN(C)C(=O)c1ccccc1N 

CHEM : 

MOL FOR: C9 H12 N2 O1 

MOL WT : 164.21 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 5.626 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 3.5326 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.5225 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 Corrected Log Koc .................................. : 0.9799 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 
84 

 Log Kow (Kowwin estimate) ......................... : 0.43 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.1629 

 Fragment Correction(s): 

 1 Nitrogen to non-fused aromatic ring ... : -0.0216 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 Corrected Log Koc .................................. : 0.8685 

 Estimated Koc: 7.387 L/kg <=========== 

DBS Amide

SMILES : CN(C)C(=O)c1ccccc1CS(N)(=O)=O 

CHEM : 

MOL FOR: C10 H14 N2 O3 S1 

MOL WT : 242.29 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 7.310 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 4.4107 

 Fragment Correction(s): 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 1 Miscellaneous S(=O) group .......... : -1.2980 

 Corrected Log Koc .................................. : 1.0825 

 Estimated Koc: 12.09 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : -0.63 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 0.5766 

 Fragment Correction(s): 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 1 Miscellaneous S(=O) group .......... : 0.1614 

 Corrected Log Koc .................................. : 0.4652 

 Estimated Koc: 2.919 L/kg <=========== 

O-desmethyl orthosofulamuron

SMILES : COc2cc(O)nc(NC(=O)NS(=O)(=O)Nc1ccccc1C(=O)N(C)C)n2 

CHEM : 

MOL FOR: C15 H18 N6 O6 S1 

MOL WT : 410.41 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 13.108 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 7.4331 

 Fragment Correction(s): 

 2 Nitrogen to non-fused aromatic ring ... : -1.0450 
85 

 1 Ether, aromatic (-C-O-C-) ........... : -0.6791 

 1 Urea (N-CO-N) ....................... : -1.0038 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Aromatic ring with 2 nitrogens ....... : -0.5964 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 1 Miscellaneous S(=O) group .......... : -1.2980 

 1 Aromatic Hydroxy (aromatic-OH) ....... : -0.0966 

 Corrected Log Koc .................................. : 0.6840 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : -0.47 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 0.6651 

 Fragment Correction(s): 

 2 Nitrogen to non-fused aromatic ring ... : -0.0432 

 1 Ether, aromatic (-C-O-C-) ........... : 0.0559 

 1 Urea (N-CO-N) ....................... : -0.0102 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Aromatic ring with 2 nitrogens ....... : 0.3984 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 1 Miscellaneous S(=O) group .......... : 0.1614 

 1 Aromatic Hydroxy (aromatic-OH) ....... : 0.1668 

 Corrected Log Koc .................................. : 1.1215 

 Estimated Koc: 13.23 L/kg <=========== 

Orthosulfamuron

SMILES : CN(C(=O)c2ccccc2NS(=O)(=O)NC(=O)Nc1nc(cc(n1)OC)OC)C 

CHEM : 

MOL FOR: C16 H20 N6 O6 S1 

MOL WT : 424.43 

--------------------------- KOCWIN v2.00 Results --------------------------- 

 Koc Estimate from MCI: 

 --------------------- 

 First Order Molecular Connectivity Index ........... : 13.646 

 Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 7.7136 

 Fragment Correction(s): 

 2 Nitrogen to non-fused aromatic ring ... : -1.0450 

 2 Ether, aromatic (-C-O-C-) ........... : -1.3582 

 1 Urea (N-CO-N) ....................... : -1.0038 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.4255 

 1 Aromatic ring with 2 nitrogens ....... : -0.5964 

 1 Misc (C=O) Group (aliphatic attach).... : -1.6047 

 1 Miscellaneous S(=O) group .......... : -1.2980 

 Corrected Log Koc .................................. : 0.3820 

 Over Correction Adjustment to Lower Limit Log Koc ... : 1.0000 

 Estimated Koc: 10 L/kg <=========== 

 Koc Estimate from Log Kow: 

 ------------------------- 

 Log Kow (Kowwin estimate) ......................... : 0.14 
86 

 Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 1.0025 

 Fragment Correction(s): 

 2 Nitrogen to non-fused aromatic ring ... : -0.0432 

 2 Ether, aromatic (-C-O-C-) ........... : 0.1118 

 1 Urea (N-CO-N) ....................... : -0.0102 

 2 Nitrogen to Carbon (aliphatic) (-N-C).. : -0.0436 

 1 Aromatic ring with 2 nitrogens ....... : 0.3984 

 1 Misc (C=O) Group (aliphatic attach).... : -0.2293 

 1 Miscellaneous S(=O) group .......... : 0.1614 

 Corrected Log Koc .................................. : 1.3480 

 Estimated Koc: 22.28 L/kg <=========== 
Appendi

Structur

In order t

parent th

herbicide

found tha

chloroxu

and paral

Life Ben

pesticide

pesticide

Table B1

Similar S

O

1

 Benchma

standardize 2

 Benchma

cycle or ea 3

 Benchma

EC50 or LC 4

 Benchma

life-cycle t 5

 Benchma

 

35 OPP Aqu

http://www

ix B. Sum

res to DOP U

to better pre

e Compendi

es had simila

at tebuthiuro

uron, fenuron

luron where 

chmarks35w

es. The benc

es. Table C1

1. Summar

Structures t

Chemical 

rthosulfamuron

Tebuthiuron 

Diuron 

Fluometuron 

Linuron 

ark = Toxicity v

ed test (usually

ark = Toxicity v

arly life stage te

ark = Toxicity v

C50 in a standar

ark = Toxicity v

test with invert

ark = Toxicity v

 

uatic Life Ben

w.epa.gov/oppe

mmary of R

Urea and odict whether

ium of Pestic

ar structures 

on, diuron, fl

n, methiuron

phenylureas

were identifie

chmarks wer

 shows the p

ry of OPP A

to DOP ure

Ac

n

>6

53

2

3

1

value x LOC. F

y with rainbow

value x LOC. F

est (usually wi

value x LOC. F

rdized test (usu

value x LOC. F

tebrates (usuall

value x LOC. F

 

chmarks are av

efed1/ecorisk_d

Relevant P

-desmethyl 

r the urea de

cide Commo

to DOP urea

luometuron, 

n, metobromu

s with simila

ed as a poten

re searched t

pesticides th

Aquatic Life 

a and o-des

Fish

cute1 Chro

61000 610

3000 930

200 26

320

1500 5.5

For acute fish, 

w trout, fathead 

For chronic fis

th rainbow trou

For acute inver

ually with midg

For chronic inv

ly with midge, 

For acute nonv

vailable at 

ders/aquatic_li

87 

Phenyl Urea

urea 

egradates wo

on Names w

a and o-desm

linuron, thid

uron, metoxu

ar structures 

ntial source o

o identify w

hat had a corr

Benchmark

smethyl DO

OPP Aquatic

Inv

onic2 Acute

00 >4865

00 14850

6 80

110

58 60

toxicity value 

minnow, or bl

sh, toxicity valu

ut or fathead m

rtebrate, toxici

ge, scud, or dap

vertebrates, tox

scud, or daphn

vascular plants,

ife_benchmark

a Toxicity

ould be poten

as searched 

methyl DOP 

diazuron, bu

uron, monol

to these deg

of aquatic to

what data wer

responding a

ks for Phen

P urea. 

c Life Benchm

vertebrates

e3 Chronic4

50 6500

00 21800

200

0.09

is generally th

luegill), and the

ue is usually th

minnow), and th

ty value is usu

phnids), and th

xicity value is u

nids), and the L

, toxicity value

k.htm (accessed

Data and 

ntially more 

to determine

urea (Wood

uturon, chlor

linuron, mon

gradates. Th

oxicity data f

re available f

aquatic life b

yl Urea Deg

marks (μg/L)

Nonvascu

Plants

4 Acute5

80

50

2.4

30

13.7

he lowest 96-ho

e LOC is 0.5. 

he lowest NOE

he LOC is 1. 

ually the lowest

he LOC is 0.5. 

usually the low

LOC is 1. 

e is usually a sh

d July 15, 2011

Compariso

toxic than th

e what urea 

d, 2009). It w

eturon, 

nuron, nebur

he OPP Aqua

for a number

for these 

benchmark. 

gradates wit

ular Vascula

Plants

5 Acute6

0.7

135

15

220

2.5

our LC50 in a 

EAC from a life

t 48- or 96-hou

west NOAEC fr

hort-term (less 

1). 

on of 

he 

was 

ron, 

atic 

r of 

th 

ar

s

6

eur 

from a 

than 
10 days) E 6

 Benchma

days) EC5

Figur

desm

2009)

DOP Ur

Buturon

Chlorot

Diuron 

Isoprotu

Linuron

N2 H

O

EC50 (usually w

ark = Toxicity v

0 (usually with

re B1. Summ

methyl DOP 

) 

rea Structure

n

oluron 

uron 

n

NH N

N

O

O

with green algae

value x LOC. F

h duckweed) an

mary of Str

urea. Most

 

e

O

e or diatoms), a

For acute vascu

nd the LOC is 

ructures of P

t structures

88 

and the LOC is

ular plants, tox

1. 

PhenylUrea

s were copie

O-desmethy

Chloreturon

Chloroxuro

Fenuron 

Fluometuro

Methiuron

N

H

O

H2N

s 1. 

xicity value is u

a Herbicides

ed from CHE

yl DOP urea

n

on 

on 

N

N O

OH

usually a shorts and DOP U

EMID Plus

a

O

-term (less than

Urea and O

 (USNLM, 

 10 

-
Metobro

Monolin

Neburon

Tebuthi

omuron 

nuron 

n

iuron 

89 

Met

Monuron 

Parafluron

oxuron 
90 

Table B2. Summary of Terrestrial Plant Toxicity Data for Urea Herbicides and Orthosulfamuron from InECOTOXICITY Database (searched August 16, 2011) 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Orthosulfamuron 

Mung bean 

Phaseolus aureus 123-1b 

VVdw 49.96 21 D EC25 < 0.00169 lbA N.A. 

Fluometuron Lettuce 

Lactuca sativa 123-1a SE 97.2 21 D EC25 .006 LBA N.R. 

Diuron Tomato 

Lycopersicon esculentum 123-1b 

VVsw 97.3 21 D EC25 0.0017 LBA N.R. 

Linuron Cucumber 

Cucumis sativus 123-1b VVsh 97.6 21 D EC25 0.0021 LBA 

0.0013-0.003 

Linuron Cucumber 

Cucumis sativus 123-1b VVsh 97.6 21 D EC25 0.0021 LBA 

0.0013-0.003 

Linuron Onion 

Allium cepa 123-1b VVrw 98.4 21 D EC25 0.0028 LBA NA 

Linuron Onion 

Allium cepa 123-1b VVrw 98.4 21 D EC25 0.0028 LBA NA 

Diuron Cucumber 

Cucumis sativus 123-1b 

VVsw 97.3 21 D EC25 0.0053 LBA N.R. 

Fluometuron Lettuce 

Lactuca sativa 123-1a SEsw 97.2 14 D EC25 0.006 LBA N.R. 

Diuron Sugarbeet 

Beta vulgaris 123-1b 

VVsw 97.3 21 D EC25 0.0087 LBA N.R. 

Fluometuron Cucumber 

Cucumis sativus 123-1b VV 97.2 21 D EC25 0.009 LBA N.R. 

Diuron Soybean 

Glycine max 123-1b 

VVsw 97.3 21 D EC25 0.012 LBA N.R. 

Fluometuron Cabbage 

Brassica oleracea 123-1a SEsh 97.2 14 D EC25 0.012 LBA N.R. 
91 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Diuron 

Garden pea 

Pisum sativum 123-1b 

VVsw 97.3 21 D EC25 0.0138 LBA N.R. 

Fluometuron Cucumber 

Cucumis sativus 123-1b VG 97.2 21 D EC25 0.019 LBA N.R. 

Fluometuron Cucumber 

Cucumis sativus 123-1a SEsw 97.2 14 D EC25 0.020 LBA N.R. 

Diuron Wheat 

Triticum aestivum 123-1b 

VVsw 97.3 21 D EC25 0.0208 LBA N.R. 

Linuron Tomato 

Lycopersicon esculentum 123-1b 

VVsw 98.4 21 D EC25 0.026 LBA NA 

Fluometuron Corn Zea mays 123-1a SE 97.2 21 D EC25 0.026 LBA N.R. Linuron Tomato 

Lycopersicon esculentum 123-1b 

VVsw 98.4 21 D EC25 0.026 LBA NA 

Linuron 

Oilseed rape 

Brassica napus 123-1b 

VVsw 98.4 21 D EC25 0.03 LBA NA 

Tebuthiuron Cabbage 

Brassica oleracea 123-1a 

SE/VV 99.6 7-21D EC25 0.03 LBA N.R. 

Linuron 

Oilseed rape 

Brassica napus 123-1b 

VVsw 98.4 21 D EC25 0.03 LBA NA 

Fluometuron Corn Zea mays 123-1a SEsw 97.2 14 D EC25 0.030 LBA N.R. Fluometuron Onion 

Allium cepa 123-1a SEsw 97.2 14 D EC25 0.031 LBA N.R. 

Linuron Rapeseed 

Brassica compestris 123-1b 

VVsw 97.6 21 D EC25 0.033 LBA N.R. 
92 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Fluometuron Tomato 

Lycopersicon esculentum 123-1a SEsw 97.2 14 D EC25 0.033 LBA N.R. 

Linuron Rapeseed 

Brassica compestris 123-1b 

VVsw 97.6 21 D EC25 0.033 LBA N.R. 

Diuron Rape 

Brassica sp. 123-1b 

VVsw 97.3 21 D EC25 0.0331 LBA N.R. 

Linuron Tomato 

Lycopersicon esculentum 123-1b 

VVsw 97.6 21 D EC25 0.034 LBA N.R. 

Linuron Tomato 

Lycopersicon esculentum 123-1b 

VVsw 97.6 21 D EC25 0.034 LBA N.R. 

Fluometuron Oat 

Avena sativa 123-1b VVG 97.2 21 D EC25 0.035 LBA N.R. 

Diuron Tomato 

Lycopersicon esculentum 123-1a SE 96.8 14 D EC25 > 0.038 LBA NA 

Fluometuron Oat 

Avena sativa 123-1a SEsw 97.2 14 D EC25 0.038 LBA N.R. 

Fluometuron Radish 

Raphanus sativus 123-1a SEsw 97.2 14 D EC25 0.045 LBA N.R. 

Linuron Onion 

Allium cepa 123-1a SEsw 97.6 14 D EC25 0.049 LBA 

0.016-0.147 

Linuron Onion 

Allium cepa 123-1a SEsw 97.6 14 D EC25 0.049 LBA 

0.016-0.147 
93 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Tebuthiuron Radish 

Raphanus sativus 123-1a 

SE/VV 99.6 7-21D EC25 0.05 LBA N.R. 

Linuron Wheat 

Triticum aestivum 123-1b 

VVsw 97.6 21 D EC25 0.051 LBA N.R. 

Fluometuron Cabbage 

Brassica oleracea 123-1b VV 97.2 21 D EC25 0.051 LBA N.R. 

Linuron Wheat 

Triticum aestivum 123-1b 

VVsw 97.6 21 D EC25 0.051 LBA N.R. 

Fluometuron Oat 

Avena sativa 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Fluometuron Soybean 

Glycine max 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Fluometuron Cucumber 

Cucumis sativus 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Fluometuron Radish 

Raphanus sativus 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Fluometuron Tomato 

Lycopersicon esculentum 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Fluometuron Cabbage 

Brassica oleracea 123-1b VV 97.2 21 D 

LOEC 0.057 LBA N.R. 

Tebuthiuron Cucumber 

Cucumis sativus 123-1a 

SE/VV 99.6 7-21D EC25 0.06 LBA N.R. 

Linuron Sugarbeet 

Beta vulgaris 123-1a SEsw 97.6 14 D EC25 0.061 LBA 

0.016-0.237 

Linuron Sugarbeet 

Beta vulgaris 123-1a SEsw 97.6 14 D EC25 0.061 LBA 

0.016-0.237 

Fluometuron Cabbage 

Brassica oleracea 123-1b VV 97.2 21 D EC25 0.065 LBA N.R. 

Fluometuron Soybean 

Glycine max 123-1a SEsw 97.2 14 D EC25 0.069 LBA N.R. 
94 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Tebuthiuron Wheat 

Triticum aestivum 123-1a 

SE/VV 99.6 7-21D EC25 0.07 LBA N.R. 

Fluometuron Ryegrass 

Lolium perenne 123-1a SEsh 97.2 14 D EC25 0.071 LBA N.R. 

Linuron Onion 

Allium cepa 123-1b 

VVsw 97.6 21 D EC25 0.073 LBA N.R. 

Linuron Onion 

Allium cepa 123-1b 

VVsw 97.6 21 D EC25 0.073 LBA N.R. 

Diuron Tomato 

Lycopersicon esculentum 123-1a SEsw 97.3 14 D EC25 0.075 LBA 

0.049-.116 

Diuron Sorghum 

Sorghum bicolor 123-1b 

VVsw 97.3 21 D EC25 0.0753 LBA N.R. 

Fluometuron Oat 

Avena sativa 123-1b VV 97.2 21 D EC25 0.078 LBA N.R. 

Diuron Onion 

Allium cepa 123-1a SEsw 97.3 14 D EC25 0.086 LBA 

0.062-.104 

Diuron Sugarbeet 

Beta vulgaris 123-1a SEsw 97.3 14 D EC25 0.092 LBA N.R. 

Diuron Rape 

Brassica sp. 123-1a SEsw 97.3 14 D EC25 0.094 LBA N.R. 

Fluometuron Oat 

Avena sativa 123-1b VV 97.2 21 D EC25 0.12 LBA N.R. 

Linuron Sugarbeet 

Beta vulgaris 123-1a SEsh 98.4 14 D EC25 0.14 LBA NA 

Linuron Sugarbeet 

Beta vulgaris 123-1a SEsh 98.4 14 D EC25 0.14 LBA NA 

Diuron Onion 

Allium cepa 123-1b 

VVsw 97.3 21 D EC25 0.148 LBA N.R. 

Linuron 

Garden pea 

Pisum sativum 123-1b 

VVsw 97.6 21 D EC25 0.17 LBA N.R. 
95 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Linuron 

Garden pea 

Pisum sativum 123-1b 

VVsw 97.6 21 D EC25 0.17 LBA N.R. 

Linuron Rape 

Brassica sp. 123-1a SEsh 97.6 14 D EC25 0.18 LBA N.R. 

Linuron Rape 

Brassica sp. 123-1a SEsh 97.6 14 D EC25 0.18 LBA N.R. 

Linuron Soybean 

Glycine max 123-1b VVsh 97.6 21 D EC25 0.21 LBA N.R. 

Linuron Soybean 

Glycine max 123-1b VVsh 97.6 21 D EC25 0.21 LBA N.R. 

Linuron Corn Zea mays 123-1b 

VVsw 97.6 21 D EC25 0.26 LBA N.R. 

Linuron Corn Zea mays 123-1b 

VVsw 97.6 21 D EC25 0.26 LBA N.R. 

Linuron Tomato 

Lycopersicon esculentum 123-1a SEsh 97.6 14 D EC25 0.28 LBA N.R. 

Linuron Tomato 

Lycopersicon esculentum 123-1a SEsh 97.6 14 D EC25 0.28 LBA N.R. 

Diuron Cucumber 

Cucumis sativus 123-1a SEsh 97.3 14 D EC25 0.34 LBA N.R. 

Diuron Corn Zea mays 123-1b 

VVsw 97.3 21 D EC25 0.39 LBA N.R. 

Linuron Cucumber 

Cucumis sativus 123-1a SEsh 97.6 14 D EC25 0.61 LBA N.R. 

Linuron Cucumber 

Cucumis sativus 123-1a SEsh 97.6 14 D EC25 0.61 LBA N.R. 

Diuron Sorghum 

Sorghum bicolor 123-1a SEsh 97.3 14 D EC25 0.81 LBA N.R. 
96 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Linuron Sorghum 

Sorghum bicolor 123-1b 

VVsw 97.6 21 D EC25 0.96 LBA N.R. 

Linuron Sorghum 

Sorghum bicolor 123-1b 

VVsw 97.6 21 D EC25 0.96 LBA N.R. 

Fluometuron Lettuce 

Lactuca sativa 123-1a SG 97.2 6 D EC25 0.97 LBA N.R. 

Diuron Wheat 

Triticum aestivum 123-1a SEsw 97.3 14 D EC25 1.05 LBA N.R. 

Linuron Sorghum 

Sorghum bicolor 123-1a SEsh 97.6 14 D EC25 1.4 LBA N.R. 

Linuron Sorghum 

Sorghum bicolor 123-1a SEsh 97.6 14 D EC25 1.4 LBA N.R. 

Diuron Sugarbeet 

Beta vulgaris 123-1a SEsh 96.8 14 D EC25 < 12 LBA NA 

Diuron Soybean 

Glycine max 123-1a SE 96.8 14 D EC25 > 12 LBA NA 

Diuron 

Oilseed rape 

Brassica napus 122-1a SEsh 96.8 14 D EC25 < 12 LBA NA 

Diuron Sorghum 

Sorghum halepense 123-1a SEsh 96.8 14 D EC25 < 12 LBA NA 

Diuron Wheat 

Triticum aestivum 122-1a SEsh 96.8 14 D EC25 < 12 LBA NA 

Diuron Onion 

Allium cepa 123-1a SEsh 96.8 14 D EC25 < 12 LBA NA 

Diuron 

Garden pea 

Pisum sativum 123-1a SEsh 97.3 14 D EC25 > 12 LBA N.R. 

Diuron Soybean 

Glycine max 123-1a SEsh 97.3 14 D EC25 > 12 LBA N.R. 

Fluometuron 

Veg.Crops(11 Sp.) 

Monocots & Dicots 122-1 SGpy 96.4 5 D 

LOEC > 2.0 LBA N.A. 
97 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Linuron Tomato 

Lycopersicon esculentum 123-1a SE 98.4 14 D EC25 > 20 LBA NA 

Linuron Tomato 

Lycopersicon esculentum 123-1a SE 98.4 14 D EC25 > 20 LBA NA 

Linuron Wheat 

Triticum aestivum 123-1a SEsh 97.6 14 D EC25 3.8 LBA N.R. 

Linuron Wheat 

Triticum aestivum 123-1a SEsh 97.6 14 D EC25 3.8 LBA N.R. 

Linuron Onion 

Allium cepa 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron 

Oilseed rape 

Brassica napus 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Soybean 

Glycine max 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Wheat 

Triticum aestivum 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Sugarbeet 

Beta vulgaris 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Soybean 

Glycine max 123-1a SE 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Sorghum 

Sorghum halepense 123-1a SE 98.4 14 D EC25 > 4.0 LBA ND 

Linuron Wheat 

Triticum aestivum 123-1a SE 98.4 14 D EC25 > 4.0 LBA NR 

Linuron Corn Zea mays 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.A. Linuron Soybean 

Glycine max 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.R. 
98 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Linuron 

Garden pea 

Pisum sativum 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.R. 

Linuron Onion 

Allium cepa 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron 

Oilseed rape 

Brassica napus 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Soybean 

Glycine max 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Wheat 

Triticum aestivum 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Sugarbeet 

Beta vulgaris 122-1a SEsh 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Soybean 

Glycine max 123-1a SE 98.4 14 D EC25 > 4.0 LBA NA 

Linuron Sorghum 

Sorghum halepense 123-1a SE 98.4 14 D EC25 > 4.0 LBA ND 

Linuron Wheat 

Triticum aestivum 123-1a SE 98.4 14 D EC25 > 4.0 LBA NR 

Linuron Corn Zea mays 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.A. Linuron Soybean 

Glycine max 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.R. 

Linuron 

Garden pea 

Pisum sativum 123-1a SEsh 97.6 14 D EC25 > 4.0 LBA N.R. 

Fluometuron Onion 

Allium cepa 123-1a SG 97.2 6 D EC25 > 4.6 LBA N.A. 

Diuron Corn Zea mays 123-1a SEsh 97.3 14 D EC25 5.7 LBA N.R. Tebuthiuron 

Crop plants(10 sp.) 

Monocots & Dicots 122-1 SG 99.6 5 D EC25 N.R. LBA N.A. 
99 

CHEMICAL 

COMMO

N NAME SPECIES 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOS

E 

TYPE TGL 

TOXICI

TY 

TOX 

LEVEL CL 

Linuron Onion 

Allium cepa 123-1a SE 98.4 14 D EC25 NR LBA NA 

Linuron 

Oilseed rape 

Brassica napus 123-1a SE 98.4 14 D EC25 NR LBA NA 

Linuron Onion 

Allium cepa 123-1a SE 98.4 14 D EC25 NR LBA NA 

Linuron 

Oilseed rape 

Brassica napus 123-1a SE 98.4 14 D EC25 NR LBA NA 

Table B3. Summary of LC50 Values for Birds for Urea Herbicides and Orthosulfamuron from Internal EP

Database (searched August 16, 2011). Bold values are lower than the values for orthosulfamuron. 

CHEMICA

L 

COMMO

N NAME SPECIES AGE 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOSE 

TYPE 

T

G

L TOXICITY Units 

Linuron 

Bobwhite quail 

Colinus virginianus 10 D 71-2a D 97.6 8 D LC50 1700 PPM 

Linuron 

Bobwhite quail 

Colinus virginianus 10 D 71-2a D 97.6 8 D LC50 1700 PPM 

Diuron 

Bobwhite quail 

Colinus virginianus 9 D 71-2a D >95 8 D LC50 1730 PPM 

Tebuthiuron 

Mallard duck 

Anas platyrhynchos 7 D 71-2b D 98 8 D LC50 > 2500 PPM 

Tebuthiuron 

Bobwhite quail 

Colinus virginianus 7 D 71-2a D 98 8 D LC50 > 2500 PPM 
100 

CHEMICA

L 

COMMO

N NAME SPECIES AGE 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOSE 

TYPE 

T

G

L TOXICITY Units 

Linuron 

Mallard duck 

Anas platyrhynchos 5 D 71-2b D 50WP 8 D LC50 3083 PPM 

Linuron 

Mallard duck 

Anas platyrhynchos 5 D 71-2b D 50WP 8 D LC50 3083 PPM 

Fluometuron 

Ringnecked pheasant 

Phasianus colchicus 

8-16 D 71-2 D Tech 8 D LC50 3150 PPM 

Linuron 

Ringnecked pheasant 

Phasianus colchicus 10 D 71-2 D 50WP 8 D LC50 3438 PPM 

Linuron 

Ringnecked pheasant 

Phasianus colchicus 10 D 71-2 D 50WP 8 D LC50 3438 PPM 

Fluometuron 

Bobwhite quail 

Colinus virginianus 1 D 71-2a D 97.5 8 D LC50 > 3474 PPM 

Fluometuron 

Mallard duck 

Anas platyrhynchos 

8-16 D 71-2b D Tech 8 D LC50 4500 PPM 

Fluometuron 

Bobwhite quail 

Colinus virginianus 

8-16 D 71-2a D Tech 8 D LC50 4620 PPM 

Monuron 

Ringnecked pheasant 

Phasianus colchicus 15 D 71-2 D Tech 8 D LC50 4682 PPM 

Orthosulfamuron 

Mallard duck 

Anas platyrhynchos 9 D 71-2b D 97.99 8 D LC50 > 4790 PPM 
101 

CHEMICA

L 

COMMO

N NAME SPECIES AGE 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOSE 

TYPE 

T

G

L TOXICITY Units 

Linuron 

Mallard duck 

Anas platyrhynchos 10 D 71-2b D 97.6 8 D LC50 4880 PPM 

Linuron 

Mallard duck 

Anas platyrhynchos 10 D 71-2b D 97.6 8 D LC50 4880 PPM 

Orthosulfamuron 

Bobwhite quail 

Colinus virginianus 14 D 71-2a D 97.99 8 D LC50 > 4980 PPM 

Linuron 

Japanese quail 

Coturnix japonica 14 D 71-2a D 50WP 8 D LC50 > 5000 PPM 

Diuron 

Japanese quail 

Coturnix japonica 12 D 71-2 D >95 8 D LC50 > 5000 PPM 

Diuron 

Ringnecked pheasant 

Phasianus colchicus 15 D 71-2 D >95 8 D LC50 > 5000 PPM 

Diuron 

Mallard duck 

Anas platyrhynchos 10 D 71-2b D >95 8 D LC50 > 5000 PPM 

Linuron 

Japanese quail 

Coturnix japonica 14 D 71-2a D 50WP 8 D LC50 > 5000 PPM 

Monuron 

Mallard duck 

Anas platyrhynchos 10 D 71-2b D Tech 8 D LC50 > 5000 PPM 

Monuron 

Japanese quail 

Coturnix japonica 12 D 71-2 D Tech 8 D LC50 > 5000 PPM 

Monuron 

Bobwhite quail 

Colinus virginianus 17 D 71-2a D Tech 8 D LC50 > 5000 PPM 

Tebuthiuron 

Mallard duck 

Anas platyrhynchos 4 D 71-2b D 99.1 8 D LC50 > 5093 PPM 
102 

CHEMICA

L 

COMMO

N NAME SPECIES AGE 

GUIDE 

LINE TYPE AI 

STUDY 

TIME 

DOSE 

TYPE 

T

G

L TOXICITY Units 

Tebuthiuron 

Bobwhite quail 

Colinus virginianus 11 D 71-2a D 99.1 8 D LC50 > 5113 PPM 

Fluometuron 

Bobwhite quail 

Colinus virginianus 10 D 71-2a D 97.8 8 D LC50 > 5620 PPM 

Table B4. Summary of LD50 Values for Birds for Urea Herbicides and Orthosulfamuron from Internal EP

Database (searched August 16, 2011). Bold values are lower than the values for orthosulfamuron. 

CHEMICAL 

COMMO

N NAME SPECIES AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYP

E 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

N

L 

Linuron 

Bobwhite quail 

Colinus virginianus 17WKS 71-1 92.4 21 D LD50 940 MGK 

712-1262 

Linuron 

Bobwhite quail 

Colinus virginianus 17WKS 71-1 92.4 21 D LD50 940 MGK 

712-1262 

Tebuthiuron 

Mallard duck 

Anas platyrhynchos 12 MOS 71-1 98 14 D LD50 > 500 MGK N.R. 

Tebuthiuron 

Bobwhite quail 

Colinus virginianus 

=>4MOS 71-1 98 14 D LD50 > 500 MGK N.R. 

Tebuthiuron 

White Rock Cross Gallus sp. Adult 71-1 98 14 D LD50 > 500 MGK N.R. 

Fluometuron 

Mallard duck 

Anas platyrhynchos 14 D 71-1 Tech 14 D LD50 2974 MGK 

2060-4296 
103 

CHEMICAL 

COMMO

N NAME SPECIES AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYP

E 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

N

L 

Diuron 

Mallard duck 

Anas platyrhynchos 3 MOS 71-1 95 14 D LD50 > 2000 MGK N.R. 

Tebuthiuron 

Mallard duck 

Anas platyrhynchos 9 MOS 71-1 98 14 D LD50 > 2000 MGK N.R. 

Fluometuron 

Mallard duck 

Anas platyrhynchos 3,4MOS 71-1 

80 WP 14 D LD50 > 2000 MGK N.A. 

Orthosulfamuron 

Mallard duck 

Anas platyrhynchos Adult 71-1 

97.99 14 D LD50 > 1960 MGK N.A. 

Orthosulfamuron 

Bobwhite quail 

Colinus virginianus 8 M 71-1 

97.99 14 D LD50 > 1960 MGK N.A. 

Table B5. Summary of NOAEC for Birds for Urea Herbicides and Orthosulfamuron from Internal EPA EDatabase (searched August 16, 2011). Bold values are lower than the values for orthosulfamuron. 

CHEMICAL 

COMMO

N NAME SPECIES AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYP

E 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

NG

L 

Tebuthiuron 

Mallard duck 

Anas platyrhynchos 

ErlyLf 71-4b 96.4 

22WKS 

LOEL > 100 PPM 

N.R. 

Tebuthiuron 

Bobwhite quail 

Colinus virginianus 

ErlyLf 71-4a 96.4 

22WKS 

LOEL > 100 PPM 

N.R. 

Fluometuron 

Mallard duck 

Anas platyrhynchos 

ErlyLf 71-4 97.8 20 wk 

LOEC 102 PPM 

N.A. 
104 

CHEMICAL 

COMMO

N NAME SPECIES AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYP

E 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

NG

L 

Orthosulfamuron 

Mallard duck 

Anas platyrhynchos 

ErlyLf 71-4 

98.56 21 Wk 

LOEL > 1280 PPM 

N.A. 

Orthosulfamuron 

Bobwhite quail 

Colinus virginianus 

ErlyLf 71-4 

98.56 21 Wk 

LOEL > 1280 PPM 

N.A. 

Fluometuron 

Bobwhite quail 

Colinus virginianus 

ErlyLf 71-4 98.8 25 wk 

LOEC 146 PPM 

N.A. 

Linuron 

Bobwhite quail 

Colinus virginianus 

ErlyLf 71-4a 98.4 

22WKS 

LOEL 300 PPM 

N.A. 

Linuron 

Mallard duck 

Anas platyrhynchos 

ErlyLf 71-4b 98.4 

20WKS 

LOEL < 300 PPM 

N.A. 

Linuron 

Bobwhite quail 

Colinus virginianus 

ErlyLf 71-4a 98.4 

22WKS 

LOEL 300 PPM 

N.A. 

Linuron 

Mallard duck 

Anas platyrhynchos 

ErlyLf 71-4b 98.4 

20WKS 

LOEL < 300 PPM 

N.A. 

Table B6. Summary of Toxicity Data for Honeybees for Urea Herbicides and Orthosulfamuron from InteECOTOXICITY Database (searched August 16, 2011). Bold values are lower than the values for orthosul

CHEMICAL 

COMMO

N NAME 

SPECIE

S AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYPE 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

NG

L 

Tebuthiuron Honey bee 

Apis mellifera 

Worker 141-1 99.1 48 hr LD50 > 100 UGB N.R. 

Orthosulfamuron Honey bee 

Apis mellifera 4-6 W 141-1 

98.54 48 hr LD50 > 100 UGB 

N.A. 
105 

CHEMICAL 

COMMO

N NAME 

SPECIE

S AGE 

GUID

E 

LINE AI 

STUD

Y 

TIME 

DOS

E 

TYPE 

TG

L 

TOX 

VALU

E 

TOX 

LEVE

L CL 

NG

L 

Orthosulfamuron Honey bee 

Apis mellifera 4-6 W 141 

98.54 48 hr LD50 > 109.4 UGB 

N.A. 

Monuron Honey bee 

Apis mellifera 

Worker 141-1 Tech 48 hr LD50 110 UGB N.R. 

Linuron Honey bee 

Apis mellifera Adults 141-1 Tech 48 hr LD50 > 120.86 UGB N.R. < 

Linuron Honey bee 

Apis mellifera Adults 141-1 Tech 48 hr LD50 > 120.86 UGB N.R. < 

Diuron Honey bee 

Apis mellifera Adult 141-1 Tech 48 hr LD50 > 145.03 UGB N.R. 
106 

Appendix C. ECOSAR Output 

Orthosulfamuron 

SMILES : c2cccc(c2NS(=O)(=O)NC(=O)(Nc1nc(cc(n1)OC)OC))C(=O)N(C)C 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C16 H20 N6 O6 S1 

MOL WT : 424.43 

Log Kow: 0.14 (KowWin estimate) 

Melt Pt: 

Wat Sol: 79.78 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Amides 

Sulfonyl Ureas 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Amides : Fish 96-hr LC50 1608.388 * 

Amides : Daphnid 48-hr LC50 477.008 * 

Amides : Green Algae 96-hr EC50 3.070 

Amides : Fish ChV 9.508 

Amides : Daphnid ChV 6.293 ! 

Amides : Green Algae ChV 0.709 

Sulfonyl Ureas : Daphnid 48-hr LC50 1951.168 * 

Sulfonyl Ureas : Green Algae 96-hr EC50 0.047 

Sulfonyl Ureas : Daphnid ChV 172.049 *! 

Sulfonyl Ureas : Green Algae ChV 0.012 ! 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 12189.570 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 5619.408 * 

 : Green Algae 96-hr EC50 1130.721 * 

 : Fish ChV 1205.637 * 

 : Daphnid ChV 373.736 * 

 : Green Algae ChV 291.533 * 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Amides : 

------- 

No limitations known at this time. 
107 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Sulfonyl Ureas : 

--------------- 

 For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical 

is greater than 5.0, or if the compound is solid and the LC50 exceeds the 

water solubility by 10X, no effects at saturation are predicted for these 

endpoints. 

 

 For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by 10X, no effects at saturation are predicted for these endpoints. 

 

 For All Chronic Toxicity Values: If the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by 10X, no effects at saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (LC50) 

Maximum LogKow: 6.4 (EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

------------------------------------------------------------------------------ 

DB amine 

SMILES : CN(C)C(=O)c1ccccc1N 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C9 H12 N2 O1 

MOL WT : 164.21 

Log Kow: 0.43 (KowWin estimate) 

Melt Pt: 

Wat Sol: 2.806E+004 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Anilines (Aromatic Amines) 

Amides 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 
108 

=========================== ================== ======== ====== ========== 

Anilines (Aromatic Amines) : Fish 96-hr LC50 155.748 

Anilines (Aromatic Amines) : Fish 14-day LC50 871.772 

Anilines (Aromatic Amines) : Daphnid 48-hr LC50 3.193 

Anilines (Aromatic Amines) : Green Algae 96-hr EC50 10.874 

Anilines (Aromatic Amines) : Fish ChV 0.949 

Anilines (Aromatic Amines) : Daphnid ChV 0.079 

Anilines (Aromatic Amines) : Green Algae ChV 7.487 

Amides : Fish 96-hr LC50 368.363 

Amides : Daphnid 48-hr LC50 120.669 

Amides : Green Algae 96-hr EC50 0.987 

Amides : Fish ChV 2.178 

Amides : Daphnid ChV 1.592 ! 

Amides : Green Algae ChV 0.274 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 2691.245 

(Baseline Toxicity) : Daphnid 48-hr LC50 1284.607 

 : Green Algae 96-hr EC50 290.897 

 : Fish ChV 264.495 

 : Daphnid ChV 89.899 

 : Green Algae ChV 79.050 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Anilines (Aromatic Amines): 

-------------------------- 

 For Fish Acute Toxicity Values: 2,3,5,6-Tetrachloroaniline is 19 times 

more toxic than predicted by this SAR. Tetrabromoaniline may be more toxic 

than predicted by this SAR as well. 

_________________________________________________________________________ 

 

DBS Amide 

SMILES : CN(C)C(=O)c1ccccc1CS(N)(=O)=O 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C10 H14 N2 O3 S1 

MOL WT : 242.29 

Log Kow: -0.63 (KowWin estimate) 

Melt Pt: 

Wat Sol: 4414 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 
109 

Amides 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Amides : Fish 96-hr LC50 3754.284 

Amides : Daphnid 48-hr LC50 852.446 

Amides : Green Algae 96-hr EC50 2.878 

Amides : Fish ChV 22.194 

Amides : Daphnid ChV 11.245 ! 

Amides : Green Algae ChV 0.405 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 31397.006 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 13182.329 * 

 : Green Algae 96-hr EC50 1931.323 

 : Fish ChV 3158.930 

 : Daphnid ChV 764.676 

 : Green Algae ChV 432.379 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 ------------------------------------------------------------------------------ 

DBS acid 

SMILES : CN(C)C(=O)c1ccccc1NS(=O)(=O)O 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C9 H12 N2 O4 S1 

MOL WT : 244.27 

Log Kow: -3.35 (KowWin estimate) 
110 

Melt Pt: 

Wat Sol: 8987 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Amides 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Amides : Fish 96-hr LC50 5.32e+005 * 

Amides : Daphnid 48-hr LC50 47315.199 * 

Amides : Green Algae 96-hr EC50 16.570 

Amides : Fish ChV 3147.680 

Amides : Daphnid ChV 624.167 ! 

Amides : Green Algae ChV 0.408 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 6.29e+006 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 1.9e+006 * 

 : Green Algae 96-hr EC50 91452.766 * 

 : Fish ChV 6.72e+005 * 

 : Daphnid ChV 68271.930 * 

 : Green Algae ChV 12468.424 * 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; 

DOP amine

SMILES : COc1cc(OC)nc(N)n1 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C6 H9 N3 O2 

MOL WT : 155.16 
111 

Log Kow: 0.95 (KowWin estimate) 

Melt Pt: 

Wat Sol: 1.108E+004 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Anilines (Aromatic Amines) 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Anilines (Aromatic Amines) : Fish 96-hr LC50 78.845 

Anilines (Aromatic Amines) : Fish 14-day LC50 225.619 

Anilines (Aromatic Amines) : Daphnid 48-hr LC50 2.376 

Anilines (Aromatic Amines) : Green Algae 96-hr EC50 9.172 

Anilines (Aromatic Amines) : Fish ChV 0.380 

Anilines (Aromatic Amines) : Daphnid ChV 0.050 

Anilines (Aromatic Amines) : Green Algae ChV 6.078 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 922.143 

(Baseline Toxicity) : Daphnid 48-hr LC50 468.756 

 : Green Algae 96-hr EC50 131.427 

 : Fish ChV 89.591 

 : Daphnid ChV 35.968 

 : Green Algae ChV 39.276 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

Anilines (Aromatic Amines): 

-------------------------- 

 For Fish Acute Toxicity Values: 2,3,5,6-Tetrachloroaniline is 19 times 

more toxic than predicted by this SAR. Tetrabromoaniline may be more toxic 

than predicted by this SAR as well. 

 

 For Daphnid and Green Algae Toxicity Values: Tetrachloro- and tetrabromaniline may be 20 times toxic than predicted by this SAR. 

 

 N-Substituted anilines are less toxic than predicted by these SARs; 

for these compounds, Neutral Organic SARs are used. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >7.8 (Fish 96-hr LC50, Daphnid 48-h LC50) 

Maximum LogKow: >3.7 (Fish 14-day LC50) 

Maximum LogKow: >4 (Green Algae 96-hr EC50 and ChV) 

Maximum LogKow: >4.3 (Fish ChV) 

Maximum LogKow: >2.4 (Daphnid ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 
112 

 ----------------------------------------------------------------------------- 

DOP urea 

SMILES : CN(C)C(=O)c1ccccc1NS(=O)(=O)O 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C9 H12 N2 O4 S1 

MOL WT : 244.27 

Log Kow: -3.35 (KowWin estimate) 

Melt Pt: 

Wat Sol: 8987 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Amides 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Amides : Fish 96-hr LC50 5.32e+005 * 

Amides : Daphnid 48-hr LC50 47315.199 * 

Amides : Green Algae 96-hr EC50 16.570 

Amides : Fish ChV 3147.680 

Amides : Daphnid ChV 624.167 ! 

Amides : Green Algae ChV 0.408 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 6.29e+006 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 1.9e+006 * 

 : Green Algae 96-hr EC50 91452.766 * 

 : Fish ChV 6.72e+005 * 

 : Daphnid ChV 68271.930 * 

 : Green Algae ChV 12468.424 * 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 
113 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 ------------------------------------------------------------------------------ 

SMILES : COc1cc(OC)nc(NC(=O)(N))n1 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C7 H10 N4 O3 

MOL WT : 198.18 

Log Kow: 0.58 (KowWin estimate) 

Melt Pt: 

Wat Sol: 1.423E+004 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Substituted Ureas 

Amides 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Substituted Ureas : Fish 96-hr LC50 612.669 

Substituted Ureas : Daphnid 48-hr LC50 1451.215 

Substituted Ureas : Green Algae 96-hr EC50 0.147 

Substituted Ureas : Fish ChV 8.207 

Substituted Ureas : Daphnid ChV 93.220 

Substituted Ureas : Green Algae ChV 0.044 ! 

Amides : Fish 96-hr LC50 337.630 

Amides : Daphnid 48-hr LC50 116.527 

Amides : Green Algae 96-hr EC50 1.082 

Amides : Fish ChV 1.996 

Amides : Daphnid ChV 1.537 ! 

Amides : Green Algae ChV 0.331 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 2419.702 

(Baseline Toxicity) : Daphnid 48-hr LC50 1176.283 

 : Green Algae 96-hr EC50 283.404 

 : Fish ChV 237.015 

 : Daphnid ChV 84.548 

 : Green Algae ChV 79.168 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 
114 

Substituted Ureas: 

----------------- 

 For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical 

is greater than 5.0, or if the compound is solid and the LC50 exceeds the 

water solubility by 10X, no effects at saturation are predicted for these 

endpoints. 

 

 For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by 10X, no effects at saturation are predicted for these endpoints. 

 

 For All Chronic Toxicity Values: If the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by 10X, no effects at saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (LC50) 

Maximum LogKow: 6.4 (EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 ------------------------------------------------------------------------------ 

O-desmethyl 

SMILES : COc2cc(O)nc(NC(=O)NS(=O)(=O)Nc1ccccc1C(=O)N(C)C)n2 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C15 H18 N6 O6 S1 

MOL WT : 410.41 

Log Kow: -0.47 (KowWin estimate) 

Melt Pt: 

Wat Sol: 328.3 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Phenols 
115 

Amides 

Sulfonyl Ureas 

Phenol Amines 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Phenols : Fish 96-hr LC50 3964.157 * 

Phenols : Fish 14-day LC50 46190.941 * 

Phenols : Daphnid 48-hr LC50 541.736 * 

Phenols : Green Algae 96-hr EC50 3168.796 * 

Phenols : Fish 30-day ChV 136.513 

Phenols : Fish 60-day ChV 0.013 

Phenols : Daphnid 21-day ChV 103.471 

Phenols : Green Algae ChV 1536.038 * 

Phenols : Fish (SW) 96-hr LC50 13090.946 * 

Phenols : Earthworm 14-day LC50 3916.285 * 

Phenols : Lemna Gibba 7-day EC50 7162.771 * 

Amides : Fish 96-hr LC50 4783.883 * 

Amides : Daphnid 48-hr LC50 1146.478 * 

Amides : Green Algae 96-hr EC50 4.410 

Amides : Fish ChV 28.280 

Amides : Daphnid ChV 15.124 ! 

Amides : Green Algae ChV 0.686 

Sulfonyl Ureas : Daphnid 48-hr LC50 5089.483 * 

Sulfonyl Ureas : Green Algae 96-hr EC50 0.046 

Sulfonyl Ureas : Daphnid ChV 433.611 *! 

Sulfonyl Ureas : Green Algae ChV 0.011 ! 

Phenol Amines : Fish 96-hr LC50 147.083 

Phenol Amines : Daphnid 48-hr LC50 5.923 

Phenol Amines : Green Algae 96-hr EC50 60.378 

Phenol Amines : Fish ChV 18.055 ! 

Phenol Amines : Daphnid 21-day ChV 7.175 

Phenol Amines : Green Algae ChV 7.803 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 39219.160 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 16780.619 * 

 : Green Algae 96-hr EC50 2621.340 * 

 : Fish ChV 3932.327 * 

 : Daphnid ChV 1000.684 * 

 : Green Algae ChV 603.848 * 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Phenols: 

------- 
116 

 For All Acute and Chronic Toxicity Values: If the log Kow of the chemical 

is greater than the value listed below, or if the compound is solid and the 

LC50, EC50 or ChV exceeds the water solubility by 10X, no effects at 

saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 7.0 (Fish 96-hr LC50, Daphnid LC50) 

Maximum LogKow: 6.4 (Fish 14-day LC50, Earthworm, Lemna) 

Maximum LogKow: 7.0 (Green Algae EC50 

Maximum LogKow: 8.0 (ChV) 

Maximum LogKow: 5.0 (Fish (SW) 96-hr LC50, Mysid) 

Maximum Mol Wt: 1000 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Sulfonyl Ureas : 

--------------- 

 For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical 

is greater than 5.0, or if the compound is solid and the LC50 exceeds the 

water solubility by 10X, no effects at saturation are predicted for these 

endpoints. 

 

 For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by 10X, no effects at saturation are predicted for these endpoints. 

 

 For All Chronic Toxicity Values: If the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by 10X, no effects at saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (LC50) 

Maximum LogKow: 6.4 (EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Phenol Amines : 

-------------- 

 For All Acute and Chronic Toxicity Values: If the log Kow of the chemical 

is greater than the value listed below, or if the compound is solid and the 

LC50, EC50 or ChV exceeds the water solubility by 10X, no effects at 

saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50) 
117 

Maximum LogKow: 7.0 (Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

------------------------------------------------------------------------------ 

o-desmethyl DOP urea

SMILES : COc1cc(O)nc(NC(=O)(N))n1 

CHEM : 

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C6 H8 N4 O3 

MOL WT : 184.16 

Log Kow: -0.04 (KowWin estimate) 

Melt Pt: 

Wat Sol: 2757 mg/L (WskowWin estimate) 

ECOSAR v1.00 Class(es) Found 

------------------------------ 

Phenols 

Substituted Ureas 

Amides 

Phenol Amines 

 Predicted 

ECOSAR Class Organism Duration End Pt mg/L (ppm) 

=========================== ================== ======== ====== ========== 

Phenols : Fish 96-hr LC50 848.565 

Phenols : Fish 14-day LC50 8576.770 * 

Phenols : Daphnid 48-hr LC50 137.081 

Phenols : Green Algae 96-hr EC50 768.347 

Phenols : Fish 30-day ChV 33.464 

Phenols : Fish 60-day ChV 0.006 

Phenols : Daphnid 21-day ChV 26.164 

Phenols : Green Algae ChV 370.382 

Phenols : Fish (SW) 96-hr LC50 2146.550 

Phenols : Earthworm 14-day LC50 1162.351 

Phenols : Lemna Gibba 7-day EC50 1336.458 

Substituted Ureas : Fish 96-hr LC50 1601.934 

Substituted Ureas : Daphnid 48-hr LC50 4283.929 * 

Substituted Ureas : Green Algae 96-hr EC50 0.147 

Substituted Ureas : Fish ChV 20.161 

Substituted Ureas : Daphnid ChV 241.913 

Substituted Ureas : Green Algae ChV 0.047 ! 

Amides : Fish 96-hr LC50 965.040 
118 

Amides : Daphnid 48-hr LC50 269.141 

Amides : Green Algae 96-hr EC50 1.493 

Amides : Fish ChV 5.705 

Amides : Daphnid ChV 3.550 ! 

Amides : Green Algae ChV 0.308 

Phenol Amines : Fish 96-hr LC50 44.406 

Phenol Amines : Daphnid 48-hr LC50 2.257 

Phenol Amines : Green Algae 96-hr EC50 18.491 

Phenol Amines : Fish ChV 4.509 ! 

Phenol Amines : Daphnid 21-day ChV 2.014 

Phenol Amines : Green Algae ChV 2.550 

=========================== ================== ======== ====== ========== 

Neutral Organic SAR : Fish 96-hr LC50 7481.463 * 

(Baseline Toxicity) : Daphnid 48-hr LC50 3375.544 * 

 : Green Algae 96-hr EC50 631.377 

 : Fish ChV 742.888 

 : Daphnid ChV 217.544 

 : Green Algae ChV 157.582 

 Note: * = asterisk designates: Chemical may not be soluble 

 enough to measure this predicted effect. 

 

 Note: ! = exclamation designates: The toxicity value was determined from 

 a predicted SAR using established acute-to-chronic ratios and ECOSAR 

 regression techniques which are documented in the supporting Technical 

 Reference Manual. When possible, this toxicity value should be 

 considered in a weight of evidence approach. 

 

Phenols: 

------- 

 For All Acute and Chronic Toxicity Values: If the log Kow of the chemical 

is greater than the value listed below, or if the compound is solid and the 

LC50, EC50 or ChV exceeds the water solubility by 10X, no effects at 

saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 7.0 (Fish 96-hr LC50, Daphnid LC50) 

Maximum LogKow: 6.4 (Fish 14-day LC50, Earthworm, Lemna) 

Maximum LogKow: 7.0 (Green Algae EC50 

Maximum LogKow: 8.0 (ChV) 

Maximum LogKow: 5.0 (Fish (SW) 96-hr LC50, Mysid) 

Maximum Mol Wt: 1000 

 

Substituted Ureas: 

----------------- 

 For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical 

is greater than 5.0, or if the compound is solid and the LC50 exceeds the 

water solubility by 10X, no effects at saturation are predicted for these 

endpoints. 

 

 For Green Algae Acute Toxicity Values: If the log Kow of the chemical is 

greater than 6.4, or if the compound is solid and the EC50 exceeds the water 

solubility by 10X, no effects at saturation are predicted for these endpoints. 
119 

 

 For All Chronic Toxicity Values: If the log Kow of the chemical is greater 

than 8.0, or if the compound is solid and the ChV exceeds the water solubility 

by 10X, no effects at saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (LC50) 

Maximum LogKow: 6.4 (EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Amides : 

------- 

No limitations known at this time. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: >8.5 (LC50) 

Maximum LogKow: >8.0 (EC50,ChV) 

Maximum Mol Wt: 1000 

 

Phenol Amines : 

-------------- 

 For All Acute and Chronic Toxicity Values: If the log Kow of the chemical 

is greater than the value listed below, or if the compound is solid and the 

LC50, EC50 or ChV exceeds the water solubility by 10X, no effects at 

saturation are predicted for these endpoints. 

 

ECOSAR v1.00 SAR Limitations: 

---------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50) 

Maximum LogKow: 7.0 (Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

Baseline Toxicity SAR Limitations: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 

Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Maximum Mol Wt: 1000 

 

 
120 

Appendix D. Ecological Toxicity Summary for Aquatic and Terrestrial Organisms from 

Orthosulfamuron 

Exposure 

Scenario Surrogate Species 

Acute Toxicity 

-- 

Chronic Toxicity 

Citation 

MRID 

Acute Toxicity 

Classification 

Birds1

Acute 

(Dose-based) 

Mallard duck 

(Anas 

platyrhynchos) 

and 

Bobwhite Quail 

(Colinus 

virginianus) 

LD50 >1960 mg a.i./kg Single oral dose 

46260107 

(Acceptable) Slightly Toxic 

Subacute 

(Dietary-based) 

Mallard duck LC50>4790 mg a.i./kg diet 

8-day Dietary 

46219040 

(Acceptable) 

Chronic 

 Mallard duck 

and 

Bobwhite Quail 

NOAEC = 1280 mg a.i./kg/day

Avian reproduction 

46578949 

(Duck-Acceptable) 

46578950 

(Quail-Acceptable) 

-- 

Mammals 

Acute 

Laboratory rat 

(Rattus norvegicus) 

LD50>5000 mg a.i./kg 

Single oral dose 

46219019 

(Acceptable) 

Practically 

Non-toxic 

Chronic NOAEC (kidney lesions) 

= 88.6 mg a.i./kg/day 

Two-Generation 

46219033 

(Acceptable) 

-- 

Chronic 

NOAEL (changes in body wt 

gain, hepatotox, nephrotox) = 5 

mg/kg/day 

Chronic Toxicity 

MRID 46578913 -- 

Insects 

Acute (contact) 

Honey bee 

(Apis mellifera L.) 

LD50>100 ug a.i./bee 

48-Hour 

46219046 

(Acceptable) Practically 

Non-toxic 

Acute (oral) LD50>109.4 ug a.i./bee 

48-Hour 

46219046 

(Supplemental) 

Freshwater fish2

Acute 

Rainbow Trout 

(Oncorhynchus 

mykiss)

LC50>122 mg a.i./L 

96-Hour 

46219042 

(Acceptable) 

Practically 

Non-toxic 

Bluegill Sunfish 

(Lepomis 

macrochirus) 

LC50>142 mg a.i./L 

96-Hour 

46219043 

(Acceptable) 

Practically 

Non-toxic 

Chronic 

Fathead Minnow 

(Pimephales 

promelas) 

NOAEC (dry wt) 

= 6.1 mg a.i./L 

Early Life Stage 

46578953 

(Acceptable) 

-- 

Freshwater Invertebrates

Acute Water Flea 

(Daphnia magna) 

EC50 (mortality/immobility) 

 > 97.3 mg a.i./L 

48-Hour 

46219044 

(Acceptable) 

Practically 

Non-toxic 

Acute 

Crayfish 

(Procambarus 

clarkii) 

EC50>129 mg a.i./L 

---- 

NOAEC = 129 mg a.i./L 

96-Hour 

46578955 

(Supplemental) 

Practically 

Non-toxic 

Chronic Water Flea 

(Daphnia magna) 

NOAEC (total length) 

= 6.5 mg a.i./L 

21-Day 

46578956 

(Acceptable) 

-- 
121 

Exposure 

Scenario Surrogate Species 

Acute Toxicity 

-- 

Chronic Toxicity 

Citation 

MRID 

Acute Toxicity 

Classification 

Estuarine/Marine Fish

Acute 

Sheepshead Minnow 

(Cyprindon 

varigatus) 

LC50>123 mg a.i./L 

96-Hour 

46578951 

(acceptable) 

Practically 

Non-toxic 

Chronic *No studies available* 

Estuarine/Marine Invertebrates

Acute 

Eastern Oyster 

(Crassostrea 

virginica) 

EC50>97 mg a.i./L 

96-Hour 

46578957 

(Acceptable) 

Slightly Toxic 

Acute 

Mysid Shrimp 

(Americamysis 

bahia) 

LC50>122 mg a.i./L 

96-Hour 

46578952 

(Acceptable) 

Practically 

Non-toxic 

Chronic Mysid Shrimp NOAEC = 27 mg a.i./L 

29 Days 

46578954 

(Supplemental) 

-- 

Terrestrial Plants 

Monocot 

Rice 

(Oryza sativa) 

EC25 (dry wt) = 0.078 lb a.i./A 

---- 

NOAEC = 0.0436 lb a.i./A 

Seedling Emergence 

46578941 

(Acceptable) NA 

Onion 

(Allium cepa)

EC25 (dry wt)=0.0048 lb a.i./A 

---- 

NOAEC = 0.00169 lbs a.i./A 

Vegetative Vigor 

46578942 

(Supplemental) NA 

Dicot 

Radish 

(Raphanus sativus) 

EC25=0.040 lb a.i./A 

---- 

NOAEC = 0.015 lb a.i./A 

Seedling Emergence 

46578941 

(Acceptable) 

NA 

Carrot 

(Daucus carota) 

EC25 = 0.00012 lb a.i./A 

EC05 = 0.000027 lb a.i./A 

---- 

NOAEC < 0.0000664 

Vegetative Vigor 

46578942 

(Supplemental) 

NA 

Aquatic Plants 

Aquatic vascular 

Plants 

Duckweed 

(Lemna gibba) 

EC50 (frond number) =0.0007 

mg a.i./L 

------- 

NOAEC = 0.00026 mg a.i./L 

7-Day Study 

46578939 

(Acceptable) 

NA 

EC50 (frond number) = 

0.00075 mg a.i./L 

---- 

NOAEC = 0.00022 mg a.i./L 

7-Day Study 

46578940 

(Acceptable) 

NA 

Aquatic 

Nonvascular 

plants3

Freshwater Diatom 

Navicula pelliculosa 

EC50 (biomass) = 0.8 mg a.i./L 

----- 

NOAEC = 0.28 mg a.i./L 

96-Hour 

46578935 

(Supplemental) 

NA 

Marine Algae3 Marine Diatom 

(Skeletonema 

costatum) 

EC50 (biomass) 

= 0.08 mg a.i./L 

------- 

NOAEC = 0.021 mg a.i./L 

46578936 

(Supplemental) NA 

1

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

 Freshwater fish may be surrogates for aquatic-phase amphibians. 3

 Test material was IR5878 50WG with 49.96% orthosulfamuron. 

 
122 

Appendix E. Results from Screening Imbibition Program (SIP) and the Screening Tool for 

Inhalation Risk Assessment (STIR) 

The Screening Imbibition Program (SIP v.1.0, Released June 15, 2010) was used to calculate an 

upper bound estimate of exposure using orthosulfamuron’s solubility (38,900 mg/L, pH 8.5 at 

20o

C, MRID 44621909), the most sensitive acute and chronic avian toxicity endpoints (Bobwhite 

Quail with LD50 >1960 mg/kg-bw and mallard duck NOAEC = 1280 mg/kg-diet, respectively) 

and the most sensitive acute and chronic mammalian toxicity endpoints (Rat LD50 >5000 mg/kgbw and NOAEL = 5 mg/kg-bw or 100 mg/kg-diet, respectively). Based on the output, exposure 

through drinking water alone is potential acute and chronic risk to small birds and a potential 

chronic risk to small mammals. Although, due to the use of the non-definitive acute values 

where no mortality was observed at those reported levels, the potential for acute risk is expected 

to be quite conservative. Results from SIP are shown below. 

Inhalation is another potential exposure route for terrestrial vertebrates. Based on the vapor 

pressure of orthosulfamuron (8.37 x 10-7 Torr at 20oC; MRID 46219010), a semivolatile 

compound from dry nonadsorbing surfaces and non-volatile from water and moist surfaces, and 

therefore risk from inhalation is not expected. The 4-hr LC50 inhalation study using rats was 

greater than 2.19 mg/L (MRID 46219021) (USEPA, 2007, D319264). The STIR model 

(Screening Tool for Inhalation Risk) was used to evaluate inhalation risk to birds. The nondefinitive acute oral values for both birds and mammals were used in the model. Based on STIR, 

risk to birds from inhalation alone is not expected. Results from STIR are shown below. 
123 

SIP Version 1.0. August, 19, 2010

Results From STIR Version 1.0, November 23, 2010
124 

Welcome to the EFED 

Screening Tool for Inhalation Risk

This tool is designed to provide the risk assessor with a rapid method for determining the potential

significance of the inhalation exposure route to birds and mammals in a risk assessment.

Input

Application and Chemical Information

Enter Chemical Name Orthosulfamuron

Enter Chemical Use Rice

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 424.4

Enter Chemical Vapor Pressure (mmHg) 8.37E-07

Enter Application Rate (lb a.i./acre) 0.067

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 1960

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000

Enter Lowest Rat Inhalation LC50 (mg/L) 2.19

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 1.91E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.40E-03

Adjusted Inhalation LD50 4.79E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 5.02E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 6.44E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.34E-03 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 1.91E-02

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.02E-03

Adjusted Inhalation LD50 1.30E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.32E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 8.09E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 6.21E-05 Exposure not Likely Significant

**NOTE**: When entering values, press

in order to update linked cells.
125 

Appendix F. Preliminary Estimated Environmental Concentration for the Parent and 

Degradates Using the Tier I Rice Model (version 1, May 8, 2007). 

Tier 1 Rice Model - Signed May 8, 2007 

 

Cw = mai / 0.00105 + 0.00013 Kd 

Cw = mai / 0.00105 + 0.0000013 KOC 

Kd = 0.01 KOC 

Where: 

Cw = water concentration [μg/L] 

Mai mass applied per unit ara [kg/ha] 

Kd = water-sdiment patitioning coefficient [L/kg] 

KOC = organic carbon partitioning coeficient [L/kg] 

 

Conversion f Application Rate from lbs a.i./acre to kg a.i./hectare 

1 kg=2.205 lbs 

1 hectare = 2.471 acres 

application rate in kg a.i./hectare = lbs ai/acre x (1 kg/2.205 

lbs) x (2.471 acre/1 hectare 

 

Concentration Changes over time were calculated using the following equation: 

Cw, t = Cw-initial x exp(-kt) 

Where: 

Cw=Concentration in water at time t or the initial concentration in water 

exp=base e 

k=single first order rate constant for aerobic aquatic metabolism in 1/days 

t=time (days) 

Table F1. Concentrations Estimated For Parent

App Rate (lbs 

a.i./acre) 

App Rate 

(kg 

a.i./hectare) 

Number 

of App 

App 

Interval Kd1

Concentration of Orthosulfamuron in 

μg/L2

 

Peak 21-day 

Average 

60-day 

Average

Annual 

Average

0.067 0.07508254 1 NA 1.98 57 37 34 9 

0.067 0.07508254 1 NA 20.68 20 17 12 3 

App=application; NA=not applicable 

1 Kd was used in calculations because the KOC calculation is based on a conversion from Kd. 

2 The rate constant used to calculate reductions in concentration over time was the average of the rate 

constants in the California and Arkansas sediments (combined values) in the aerobic aquatic metabolism 

study (MRID 4621907). The combined rate constant for California was 0.024 and the combined rate 

constant for Arkansas was 0.014 resulting in an average value of 0.019. 
126 

Preliminary Estimate of Exposure to Degradates Concentrations of parent were converted to potential concentrations of degradates using the following equDegradate EEC = 

Maximum Amount Degrada

Molecular Weight of Orthosulamuron Molecular Weight of Degradate Estimated concentration of parent in water × ×

Example Calculation for DOP urea = 57 μg/L ×155.16÷424.4 × 0.47 = 10 μg/L

Notes on Analysis Shown in Table F2. ‐ DB amine and DOP amine were detected near 1% applied radioactivity in the aerobic metabolism study. See 

discussed well in DER. This 1% was combined with the maximum amount of unextracted residues observed metabolism test systems. 

‐ DOP urea was detected at a maximum in the Arkansas pyramidine labeled system. Residues were combined 

amount of unextracted residues observed in that study 

‐ Toxicity Values Were Estimated In ECOSAR. For the ureas, chronic values are shown based on values for t

urea and DOP urea. 

‐ Reliable decline curves could not be determined. For DOP amine, residues increased and decreased over tim

may have been due to variability in the analytical method. DB amine was detected at the maximum amount ainterval. DOP urea was detected at the maximum amount near or at the final sampling interval. 
127 

Table F2. Estimated EECs for Orthosulfamuron and Degradates with Use on Rice.

Compound

Molecular

Weight

(g/mole)

Molecular

Weight Ratio

Maximum

Observed in

Aerobic Aquatic

Study

EEC

(ug/L)

Fish

Chronic

Value

Daphnid

Chronic

Value

Orthosulfamuron 424.4 1 57 6100 6500DB amine 164.21 0.39 0.01 0.2 949 79DB amine + unextracted

residues 164.21 0.39 0.34 7 949 79

DOP amine 198.21 0.47 0.01 0.3 380 50DOP amine +

unextracted residues 198.21 0.47 0.34 9 380 50

DOP urea 155.16 0.37 0.47 10

1996

6

15372010

DOP urea + O‐

desmethyl DOP urea 155.16 0.37 0.5 10

1996

6

15372010

DOP urea+‐desmethyl

DOP urea + unextracted

residues 155.16 0.37 0.72 15

1996

6

15372010

EEC = EEC for parent x MW ratio x Maximum observed in Aerobic Aquatic StudyMolecular Weight Ratio = Molecular weight of transformation product divided by molecular weight of parent.
128 

Appendix G: Example T-Rex Input and Output for Orthosulfamuron. 

Table X. 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 

0 16.08 ##### 7.37 ##### 9.05 #DIV/0! 1.01 ##### 

Size class not used for dietary risk quotients 

 

Table X. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients 

Size 

Class 

(grams) 

Adjusted 

LD50 

EECs and RQs 

Short Grass Tall Grass Broadleaf Plants/ 

Small Insects 

Fruits/Pods/ 

Seeds/ 

Large Insects 

Granivore 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

15 10989.15 15.33 0.00 7.03 0.00 8.62 0.00 0.96 0.00 0.21 0.00 

35 8891.40 10.60 0.00 4.86 0.00 5.96 0.00 0.66 0.00 0.15 0.00 

1000 3845.80 2.46 0.00 1.13 0.00 1.38 0.00 0.15 0.00 0.03 0.00 

 

Table X. Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients 

LC50 

(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 

0 16.08 ##### 7.37 ##### 9.05 #DIV/0! 1.01 ##### 

Size class not used for dietary risk quotients 

 

Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients 

NOAEC 

(ppm) 

EECs and RQs 

Short Grass Tall Grass 

Broadleaf 

Plants/ 

Small Insects 

Fruits/Pods/ 

Seeds/ 

Large Insects 
129 

EEC RQ EEC RQ EEC RQ EEC RQ 

100 16.08 0.16 7.37 0.07 9.05 0.09 1.01 0.01 

Size class not used for dietary risk quotients 

 

Table X. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk Quotients 

Size 

Class 

(grams) 

Adjusted 

NOAEL 

EECs and RQs 

Short Grass Tall Grass Broadleaf Plants/ 

Small Insects 

Fruits/Pods/ 

Seeds/ 

Large Insects 

Granivore 

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ 

15 10.99 15.33 1.40 7.03 0.64 8.62 0.78 0.96 0.09 0.21 0.02 

35 8.89 10.60 1.19 4.86 0.55 5.96 0.67 0.66 0.07 0.15 0.02 

1000 3.85 2.46 0.64 1.13 0.29 1.38 0.36 0.15 0.04 0.03 0.01 

 

T-Rex can be found at: http://www.epa.gov/oppefed1/models/terrestrial/trex_usersguide.htm 
130 

Appendix H: Example Terrplant (v. 1.2.2) Input and Output for 

Orthosulfamuron. 

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. 

 

Table 1. Chemical Identity. 

Chemical Name Orthosulfamuron 

PC code 108209 

Use Rice 

Application Method Aerial 

Application Form Spray 

Solubility in Water 

(ppm) 38900 

 

Table 2. Input parameters used to derive EECs. 

Input Parameter Symbol Value Units 

Application Rate A 0.067 y 

Incorporation I 1 none 

Runoff Fraction R 0.05 none 

Drift Fraction D 0.05 none 

 

Table 3. EECs for Orthosulfamuron. Units in y. 

Description Equation EEC 

Runoff to dry areas (A/I)*R 0.00335 

Runoff to semi-aquatic areas (A/I)*R*10 0.0335 

Spray drift A*D 0.00335 

Total for dry areas ((A/I)*R)+(A*D) 0.0067 

Total for semi-aquatic areas ((A/I)*R*10)+(A*D) 0.03685 

 

Table 4. Plant survival and growth data used for RQ derivation. Units are in y. 

 Seedling Emergence Vegetative Vigor 

Plant type EC25 NOAEC EC25 NOAEC 

Monocot 0.048 0.00169 0.078 0.0436 

Dicot 0.04 0.015 0.00012 0.000027 

 

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

runoff and/or spray drift.* 

Plant Type Listed Status Dry Semi-Aquatic Spray Drift 

Monocot non-listed 0.14 0.77 <0.1 

Monocot listed 3.96 21.80 1.98 

Dicot non-listed 0.17 0.92 27.92 

Dicot listed 0.45 2.46 124.07 

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group. 
131 

Appendix I. List of Label Statements Relevant to the Environmental Risk Assessment. 

EPA Registration Number 80289-13

Before applying...water levels must be drained or the water level lowered to allow exposure of 

the weed leaf surface for maximum uptake of the product by leaves. It is recommended that the 

field be drained or the water level lowered the day before the application. If the field cannot be 

drained before application, the water level must be reduced so that at least 70% of the weed leaf 

surface area is above the floodwater. Bring the field to normal flood-level 24-48 hours after 

application. 

• It is essential that rice be flushed after a foliar application to maximize root absorption 

resulting in commercially acceptable weed control. 

• Nozzle set must use a coarse spray quality category per ASAE S572 Standard 

• If endangered plant species occur in proximity of the application site, the following 

mitigation measure is required to avoid adverse nontarget effects: 

Leave untreated downwind buffer zones of 25 feet for ground applications or 200 feet for 

aerial applications. 

To determine whether your county has an endangered terrestrial plant species, consult 

http://www.epa.gov/espp/use-map.htm. Endangered Species Bulletins may also be obtained 

from state or county extension offices or state pesticide agencies. If the bulletin is not 

available for your specific area, check with the appropriate local state agency to determine if 

known populations or terrestrial endangered plants occur in the area to be treated. 

• Do not use STRADA XT on sand and loamy sand soils. 

• Do not use treated rice fields for the aquaculture or edible fish and crustacean (crayfish). 

• Do not use water from rice cultivation after a STRADA XT application to irrigate any crop 

other than rice. 

• In Arkansas, STRADA XT must not be applied in an area from one mile west of Highway #1 

to one mile east of Highway#163 from the CraigheadPoinsett County line to the CrossPoinsett County line. Furthermore, no aerial application is allowed in the area of Poinsett 

County one mile west of Highway#1 to two miles west of Highway#1 and one mile east of 

Highway#163 to Ditch #10, from the Craighead-Poinsett County line to the Cross-Poinsett 

county line. 

EPA Registration Number 80289-6

• Do not apply STRADA CA to the same field in the same growing season that an application 

of STRADA GR has been applied. 

EPA Registration Number 80289-5

• Before applying STRADA CA to water seeded rice, water level in the rice field must be 
132 

drained or lowered to allow exposure of the weed leaf surface for maximum uptake of the 

product by the leaves. It is recommended that the field be drained or the water level be 

lowered the day before application. If the field cannot be drained before application, the 

water level must be reduced so that at least 70% of the weed leaf surface area is above the 

floodwater. Bring the field to normal flood level 24-48 hours after application. 

• The distance between the outer most nozzles on the boom must not exceed 70% of the 

wingspan or fixed-wing aircraft or 80% of the helicopter rotor width 

• Nozzle set up must use a coarse spray quality category per ASAE S-572 Standard 

• If endangered plant species occur in proximity of the application site, the following 

mitigation measure is required to avoid adverse nontarget effects: 

Leave untreated downwind buffer zones of 25 feet for ground applications or 200 feet for 

aerial applications. 

To determine whether your county has an endangered terrestrial plant species, consult 

http://www.epa.gov/espp/use-map.htm. Endangered Species Bulletins may also be obtained 

from state or county extension offices or state pesticide agencies. If the bulletin is not 

available for your specific area, check with the appropriate local state agency to determine if 

known populations or terrestrial endangered plants occur in the area to be treated. 

• Application is not allowed when wind speeds exceed 10 mph due to risk of direct drift to 

non-target sensitive crops or locations. 

EPA Registration Number MO080002

• The spray boom height may not exceed 15 feet 

• Do not make more than 1 application or apply more than 2.1 ounces of STRADA WG 

(equivalent to 0.067 lb a.i./A) during the growing season in both the first and ratoon crops 

combined. 

EPA Registration Number AR-08-0012

• Do not apply where runoff or irrigation water may flow directly onto agricultural land other 

than rice fields. 

• Do not make more than 1 application or apply more than 2.1 ounces of STRADA WG 

(equivalent to 0.067 lb a.i./A) during the growing season in both the first and ratoon crops 

combined. 

EPA Registration Number LA-08-0007

• Do not apply where runoff or irrigation water may flow directly onto agricultural land other 

than rice fields. 

• Do not make more than 1 application or apply more than 2.1 ounces of STRADA WG 

(equivalent to 0.067 lb a.i./A) during the growing season in both the first and ratoon crops 
133 

combined. 

EPA Registration Number TX080007

• Do not apply where runoff or irrigation water may flow directly onto agricultural land other 

than rice fields. 

• Do not make more than 1 application or apply more than 2.1 ounces of STRADA WG 

(equivalent to 0.067 lb a.i./A) during the growing season in both the first and ratoon crops 

combined. 
134 

Appendix J. Identification of Transformation Products and Listing of the Maximum 

Amounts Observed in Fate Studies. 

 Table J1. Structures of Orthosulfamuron and Its Environmental Transformation 

Products. 

Code Name/ Synonym/ 

Chemical Name/ Formula/MW/ SMILES Chemical Structure 

Orthosulfamuron, IR5878, S3, H3 

IUPAC: 1-(4,6-Dimethoxypyrimidin-2-yl)-3-[2-

(dimethylcarbamoyl)phenylsulfamoyl]urea. 

CAS: 2-[[[[[(4,6-Dimethoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]amino]-

N,N-dimethylbenzamide 

CAS No.: 213464-77-8 

Formula: C16H2ON6O6S 

MW: 424.4 g/mol 

SMILES:

CN(C(=O)c1ccccc1NS(=O)(=O)NC(=O)Nc1nc(cc(n1)O

C)OC)C 

DBS acid, IR7863, S1, H1 

IUPAC: (2-Dimethylcarbamoylphenyl)sulfamic acid 

CAS: Sodium (2-dimethylcarbamoylphenyl)sulfamate 

Other: 2-Sulfamino-N,N-dimethylbenzamide 

CAS No.: 

Formula: C9H12N2SO4

MW: 244.28g/mol 

SMILES: CN(C)C(=O)c1ccccc1NS(=O)(=O)O 

DB amine, S4, H4 

IUPAC: (2-2-Amino-N,N-dimethylbenzamide 

Formula: C9H12N2O 

MW: 164.21 g/mol 

SMILES: CN(C)C(=O)c1ccccc1N 

DOP amine, S13, H6 

IUPAC: 4,6-Dimethoxypyrimidin-2-yl amine 

2-Amino-4,6-dimethoxypyrimidine 

N

O

NH

S

O

O

NH

O

NH

N

N

O

O

N

NH S

O

O

O

OH

N

NH2

O

N

O
135 

Code Name/ Synonym/ 

Chemical Name/ Formula/MW/ SMILES Chemical Structure 

Formula: C7H10N4O3 

MW: 198.21 

SMILES: COc1cc(OC)nc(N)n1 

DOP urea, IR7825, S12, H5 

IUPAC: N-(4,6-Dimethoxypyrimidin-2-yl)-urea 

CAS: 4,6-Dimethoxy-2-pyrimidinyl urea 

Formula: C6H9N3O2 

MW: 155.16 

SMILES: COc1cc(OC)nc(NC(N)=O)n1 

DBS amide, S2, H2 

Other: 2-Sulfamoylamino-N,N-dimethylbenzamide 

Formula: C9H13N3SO3 

MW: 243.28 g/mole 

SMILES: CN(C)C(=O)c1ccccc1CS(N)(=O)=O 

O-desmethyl IR5878, O-desmethyl orthosulfamuron, 

IR8181, S9 

IUPAC: 1-(4-Hydroxy-6-methoxypyrimidin-2-yl)-3-[2-

(2-dimethylcarbamoyl)phenylsulfamoyl]urea 

CAS: 1-[2(Dimethylcarbamoyl)phenylsulfamyl]-3-(4-

hydroxy-6-methoxypyrimidin-2-yl)urea 

SMILES:

COc2cc(O)nc(NC(=O)NS(=O)(=O)Nc1ccccc1C(=O)N(C

)C)n2 

S11 (multiple unresolved compounds) 

S5 (multiple unresolved compounds) 

o-desmethyl DOP urea, S15 

MW: 184.16

SMILES: COc1cc(O)nc(NC(N)=O)n1 

S6 

N2 H NH N

N

O

O

O

N

NH S NH2

O

O

O

N

NH S NH NH N

N

OH

O

O O

O

O

N

H

O

H2N

N

N O

OH
136 

Code Name/ Synonym/ 

Chemical Name/ Formula/MW/ SMILES Chemical Structure 

S8 

IR8181 

S16 

S7 

Abbreviations: nd = not detected; AR =applied radioactivity; MW =molecular weight. 

Table J2. Structures of Orthosulfamuron and Its Environmental Transformation 

Products. Full chemical names are provided in Table J1.

Common Name or 

Code Name Study Type MRID Max %AR or Conc. 

(sampling interval) 

Final %AR or Conc. 

(sampling interval) 

Descriptive Information 

for Value 

Orthosulfamuron, 

IR5878, S3, H3 

Hydrolysis 46219015 

33 ( 37 days) pH 7, 25oC 

56 (176 days) pH 9, 25o

C 

nd (5 days) pH 4, 50o

C 

18 (5 days) pH 7, 50o

C 

72 (5 days) pH 9, 50oC 

Hydrolysis 46219016 

15 (1 hr) 1 hr, pH 4, 50oC 

27 (52 hrs) 52 hrs, pH 7, 50o

C 

33 (13 days) 13 days, pH 9, 50oC 

Aqueous 

photolysis 46588509 95 (7 days) 

Anaerobic 

Aquatic 46578967 

22 (180 days) AR pyr 

19 (180 days) AR phe label 

7 (180 days) CA pyr label 

Aquatic Field 

Dissipation 46578985 

0.083 mg/kg (0day) nd (123 day) AR soil 

0.171 mg/kg (3 day) <0.005 mg/kg (60 day) AR sediment 

0.017 mg/L (3 day) <0.005 (22 day) AR water 

0.103 mg/kg (0 day) <0.005 mg/kg (194 day) CA Soil 

0.056 mg/kg (3 day) nd (60 day) CA sediment 

DBS acid, IR7863, 

S1, H1 

Hydrolysis 46219015 

58 ( 37 days) 58 ( 37 days) pH 7, 25o

C 

23 (176 days) 23 (176 days) pH 9, 25oC 

86 (5 days) 86 (5 days) pH 4, 50o

C 

66 (5 days) 66 (5 days) pH 7, 50o

C 

12 (5 days) 12 (5 days) pH 9, 50oC 

Aerobic 

Aquatic 46219017 54 (90 day) 54 (90 days) AR phe label 

61 (61 days) 61 (61 days) CA phe label 

Anaerobic 

aquatic 46578967 12 (100 days) 9 (180 days) AR phe label 

39 (150 days) 39 (150 days) CA pyr label 

Aquatic field 46578985 0.047 mg/kg(7 days) nd (550 days) AR soil 
137 

Common Name or 

Code Name Study Type MRID Max %AR or Conc. 

(sampling interval) 

Final %AR or Conc. 

(sampling interval) 

Descriptive Information 

for Value 

 dissipation 0.065 mg/kg (7 days) nd (60 days) AR sediment 

0.011 mg/L (15 days) <0.005 mg/L (60 days) AR water 

<0.02 mg/kg (7 days) nd (553 days) CA soil 

<0.02 mg/kg (7 days) nd (60 days) CA sediment 

<0.005 mg/L (15 days) nd (60 days) CA water 

DB amine, S4, H4 

Hydrolysis 46219015 

2 (37 days) 2 (37 days) pH 7, 25o

C 

13 (176 days) 13 (176 days) pH 9, 25oC 

13 (5 days) 13 (5 days) pH 4, 50oC 

11 (5 days) 11 (5 days) pH 7, 50oC 

6 (5 days) 6 (5 days) pH 9, 50oC 

Aerobic 

aquatic 46219017 <1 (90 days) <1 (90 days) AR 

1 (90 days) 1 (90 days) CA 

Anaerobic 

aquatic 46578967 6 (42 days) 5 (42 days) AR phe label 

6 (100 days) 4 (150 days) CA phe label 

DOP amine, S13, 

H6 Hydrolysis 46219016 

4 (1hr) 4 (1hr, pH 4, 50o

C) pH 4, 50o

C 

11 (52 hrs) 11 (52 hrs) pH 7, 50oC 

53 (13 days) 53 (13 days) pH 9, 50oC 

Aerobic 

aquatic 46219017 1 (90 days) 1 (90 days) AR sediment 

1 (30 days) 1 (90 days) CA sediment 

Anaerobic 

Aquatic 46578967 <1 (100 days) <1 (180 days) AR pyr label 

DOP urea, 

IR7825, S12, H5 Hydrolysis 46219016 

78 (1hr) 78 (1hr) pH 4, 50o

C 

60 (52 hrs) 60 (52 hrs) pH 7, 50oC 

13 (13 days) 13 (13 days) pH 9, 50oC 

Aerobic 

Aquatic 46219017 47 (90 days) 47 (90 days) AR pyr label 

40 (30 days) 36 (61 days) CA pyr label 

Anaerobic 

Aquatic 46578967 12 (42 days) 3 (180 days) AR pyr label 

19 (59 days) 16 (150 days) CA pyr label 

Aquatic Field 

Dissipation 46578985 

0.07 mg/kg (186 day) 0.024 mg/kg (123 day) AR soil 

0.147 mg/kg (15 day) 0.041 mg/kg (60 day) AR sediment 

<0.005 mg./L (60 days) <0.005 mg./L (60 days) AR water 

0.089 (194 day) 0.033 mg/kg (553 day) CA soil 

0.162 mg/kg (7 day) 0.023 mg/kg (60 day) CA sediment 

<0.005 mg/L (30 days) nd (60 days) CA water 

DBS amide, S2, 

H2 

Hydrolysis 46219015 

7 ( 37 days) 7 ( 37 days) pH 7, 25o

C 

8 (176 days) 8 (176 days) pH 9, 25oC 

9 (0.13 days) 1 (0.04 days) pH 4, 50oC 

8 (2 days) 5 (5 days) pH 7, 50oC 

10 (5 days) 10 (5 days) pH 9, 50oC 

Anaerobic 

aquatic 46578967 

4 (180 days) 4 (180 days) AR phe label 

4 (150 days) 4 (150 days) CA phe label 

Aerobic 

aquatic 46219017 4 (90 days) 4 (90 days) AR phe label 

4 (61 days) 4 (61 days) CA phe label 

O-desmethyl Aerobic 46219017 9 (90 days) 9 (90 days) AR pyr label 
138 

Common Name or 

Code Name Study Type MRID Max %AR or Conc. 

(sampling interval) 

Final %AR or Conc. 

(sampling interval) 

Descriptive Information 

for Value 

IR5878, Odesmethyl 

orthosulfamuron, 

IR8181, S9 

aquatic 7 (90 days) 7 (90 days) AR phe label 

7 (30 days) 6 (90 days) CA pyr label 

6 (44 days) 6 (61 days) CA phe label 

Anaerobic 

aquatic 46578967 

19 (100 days) 16 (180 days) 

AR phe label 

17 (180 days) 17 (180 days) AR pyr label 

12 (59 days) 4 (150 days) CA pyr label 

13 (35 days) 4 (150 days) CA phe label 

S11 (multiple 

unresolved 

compounds) 

Aerobic 

aquatic 46219017 3 (90 days) 3 (90 days) AR 

6 (90 days) 6 (90 days) CA 

Anaerobic 

Aquatic 46578967 23 (180 days) 23.18 (180 days) AR pyr label 

S5 (multiple 

unresolved 

compounds) 

Aerobic 

aquatic 46219017 4 (90 days) 4 (90 days) AR 

4 (90 days) 4 (90 days) CA 

Anaerobic 

aquatic 46578967 

22 (180 days) 22 (180 days) AR phe label 

16 (100 daysphe) 15, (150 days) CA phe label 

o-desmethyl DOP 

urea, S15 

Aerobic 

aquatic 46219017 <1 (90 days) <1 (90 days) AR 

4 (44 days) 3 (61 days) CA 

Anaerobic 

aquatic 46578967 3 (180 days, AR pyr) 3 (180 days, AR pyr) 

S6 Aerobic 

aquatic 46219017 <1 (7 days) 0.0 (90 days) AR 

nd nd CA 

S8 Aerobic 

aquatic 46219017 <1 (90 days) <1 (90 days) AR 

nd nd CA 

Anaerobic 

aquatic 46578967 2 (180 days) 2 (180 days) AR phe label 

2 (100 days) 2 (150 days) CA phe label 

IR8181 Aquatic field 

dissipation 46578985 nd nd CA or AR 

S16 

Anaerobic 

aquatic 46578967 

<1 (180 days) <1 (180 days) AR pyr label 

1 (0 days) <1 (180 days) AR phe label 

1 (0 days) < LOD (150 days) CA phe label 

S7 Anaerobic 

aquatic 46578967 <1 (15 days) < LOD (180 days) AR phe label 

<1 (15 days) <LOD (150 days) CA phe label 

Abbreviations: %AR=percent applied radioactivity present as the identified compound; 

Conc.=concentration measured in field study; phe = phenyl ring radiolabeled; pyrimidinyl ring 

radiolabeled; CA=California; AR=Arkansas; LOD=limit of detection
139 

Appendix K. Calculations for Ground Water Used for Irrigation Exposure 

To estimate exposure to plants when paddy water contaminated by orthosulfamuron is applied to 

crops, the following method was used. 

Assume a field is irrigated with one inch of water containing 57 μg/L orthosulfamuron. 

One acre has 6,272,640 cubic inches of water on the field. The one acre field with 1 inch of 

water has 3,630 cubic ft of water (6,272,640 x 0.00058 cubic ft/cubic inch). The field has 27,156 

gallons of water (3,630 cubic ft x 7.481 gallons/cubic ft). Therefore, one inch of water on the 

one acre field weighs 226,625 lbs (27,156 gallons x 8.3453 lbs/gallon of water). 

 226,625 lb of water/acre x 57 μg/L = 0.012 lbs a.i./A 

 1,000,000,000 
140 

Appendix L. Preliminary Estimate of Exposure and Risk to Terrestrial Animals for DOP 

urea and O-desmethyl DOP urea. 

The application rate for the ureas was estimated using the following equation. 

Urea application rate = 

Maximum DOP urea observed

Molecular Weight of Orthosulamuron

Molecular Weight of DOP Urea Application Rate of Parent × ×

Where the maximum amount of DOP urea observed is the maximum amount of applied 

radioactivity observed as DOP urea over the total applied radioactivity in the hydrolysis study. 

The exact calculation is shown below. O-desmethyl DOP urea was not observed in the 

hydrolysis studies. 

= 0.067 lbs ai/A ×155.16÷424.4 × 0.78 = 0.019 lbs DOP urea/A 

 

Toxicity Inputs are shown below: 

 Test 

Species 

Source Compound 

Avian LD50 

(mg/kg-bw) 

940 Bobwhite 

Quail 

MRID 

00150170 

Linuron 

Avian LC50 

(mg/kg-diet) 

1700 Bobwhite 

Quail 

MRID 

00034769 

Linuron 

Avian 

NOAEC 

(mg/kg-diet) 

100 Bobwhite 

Quail and 

Mallard 

Duck 

MRID 

42541801, 

41864701 

Linuron 

Mammalian 

LD50 (mg/kgbw) 

677 Rat MRID 

47305223 

DOP urea 

Reported 

chronic 

Endpoint 

(mg/kg-bw) 

0.74 Rat MRID 

41463401 

Linuron 

Mammalian 

Dietary 

Concentration 

(mg/kg-diet) 

12.50 Rat MRID 

41463401, 

41864701 

Linuron 

 
141 
142 
143 

Appendix M. Data Table for Non-Guideline Studies 

Guideline Number: none

Study Titles: Special Study for Non-Target Plant Reproductive Toxicity

Rationale for Requiring the Data

As stated in the Problem Formulation, investigations/studies have indicated a small percentage of the 

label application rate of low dose high potency herbicides such as sulfonylureas (e.g. orthosulfamuron) 

may impact the reproduction of non-target terrestrial plants. However, there are no available data on 

adverse reproductive impacts to terrestrial plants from orthosulfamuron residues due to spray drift. 

Terrestrial plant reproductive toxicity data would help to screen for potential plant risks associated with 

orthosulfamuron use. Plants form the basis of most habitats and contribute significantly to overall 

environmental quality. The loss of plant reproductive output could potentially have an adverse effect on 

animals, both invertebrates and vertebrates, as many are dependant on plant reproduction for a food 

source and for habitat quality and structure. A solid understanding of the potential risks to plants is 

therefore essential for sound environmental management. A study protocol must be submitted for 

review and approved by the Agency prior to initiation of the study.

Practical Utility of the Data

How will the data be used? 

The data will be used to estimate potential reproductive risks to non-target terrestrial plants, including 

the likelihood of potential risks to endangered species, either by direct effects or by indirect effects, and 

to reduce uncertainties associated with the current ecological risk assessment. By refining the 

assessment, the Agency will be able to determine whether current labeling is appropriate and whether 

further mitigation is necessary. In the absence of this data, risks to terrestrial plants will be presumed.

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

These data, once submitted, should allow the Agency to characterize the risk posed to plant 

reproductive processes from orthosulfamuron in terrestrial ecosystems. Primary producers (i.e,. plants) 

provide food and habitat vital to ecological processes. Therefore, a solid understanding of the potential 

risks to non-target plants is essential in order to assess the environmental risks the use of 

orthosulfamuorn may pose. If the data indicate that orthosulfamuron poses significant risks to these 

non-target plant species, the Agency may explore additional decision options to minimize the risks to 

these species. The lack of these data will limit the flexibility the Agency and registrants have in 

complying with the Endangered Species Act and could result in use restrictions for orthosulfamuron 

which may otherwise be avoided, or which are unnecessarily severe.