### 1 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES



# Environmental Fate and Ecological Risk Assessment

f

or the Reregistration of Sulfometuron

- methyl: Ve getative

M an agement and O ther N on

- crop U ses

For Use as Pre/Early post Emergence Herbicide for Selective Control of Certain Broadleaf Weeds & Grasses



## O O C H 3



## S

O O

N H

N

O H

N N C H 3



## C H 3



## SULFOMETURON METHYL

PC Code: 12 2001 ; CAS Number: 74222

- 97

- 2

Note: Appendix A has been s lightly revi sed from the 11/28/07 review (DP Barcode D346171) per registrant comm ent. Prepared by:

M. Barrett

, Chemist

, Environmental Fate Reviewer, ERB V

K. Sappington, Biologist, Ecological Effects Reviewer, ERB V

Approved by: Mah Shamim, PhD, Chief ERB V Feb ruary 14, 2008

DP Barcode D3 34277

United States Environmental Protection Agency Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V 1200 Pennsylvania Ave.

Mail Code 7507P Washington, D.C. 20460

### 2 

## TABLE OF CO NTENTS

1. EXECUTIVE SUMMARY

____________________________________________________ 8

1.1. Nature of Chemical Stressor

__________________________________________________ 8

1.2. Conclusions

- Exposure Characterization

________________________________________ 8

1.3. Conclusions

- Effects Characterization

________________________________ __________ 9

1.4. Potential Risks to Non

- target Animal s and Plants

________________________________ 10

1.5. Conclusions

- Endangered Species

________________________________ ____________ 11

1.6. Identification of Uncertainties and Their Impact on the Risk Asses sment

____________ 13

1.6.1. Environmental Fate and Exposure

________________________________ ____________________ 13

1.6.2. Ecological Effects

________________________________ ________________________________ _ 14



### 2. PROBLEM FORMULATION

________________________________________________ 15

2.1. Nature of the Regulatory Action

________________________________ ______________ 15

2.2. Stressor Source and Distribution

______________________________________________ 15

2.2.1. Nature of the Chemical Stressor

________________________________ ______________________ 15

2.2.2. Overview of Pesticide Usage

________________________________ ________________________ 17

2.3. Receptors

_________________________________________________________________ 17

2.3.1. Aquatic and Terrestrial Effects

________________________________ _______________________ 17

2.3.2. Ecosystems at Risk

________________________________ ________________________________ 19

2.4. Assessment Endpoints

_______________________________________________________ 19

2.5. Conceptual Model

__________________________________________________________ 20

2.5.1. Risk Hypotheses

________________________________ ________________________________ __ 20

2.5.2. Conceptual Diagram

________________________________ _______________________________ 20

2.6. Analysis Plan

________________________________ ______________________________ 24

2.6.1. Conclusions from P revious Risk Assessments

________________________________ ___________ 24

2.6.2. Preliminary Identification of Data Gaps and Analysis Plan

________________________________ _ 25

2.6.3. Measures of Effect and Ex posure

________________________________ _____________________ 25



### 3. ANALYSIS

_______________________________________________________________ 27

3.1. USE CHARACTERIZATION

________________________________ ________________ 27

3.2. EXPOS URE CHARACTERIZATION

________________________________ _________ 33

3.2.1. Environmental Fate and Transport Characterization

________________________________ ______ 33

3.2.2. Measures of Aquatic Exposure

________________________________ _______________________ 44

3.2.2.1. Aquatic Exposure Monitoring and Field Data

________________________________ ______ 44

3.2.2.2. Aquatic Exposure Modeling

________________________________ ____________________ 44

3.2.3. Measures of Terrestrial Exposure

________________________________ ____________________ 53

3.2.3.1. Terrestrial Exposure Modeling

________________________________ __________________ 53

3.2.3.2. Residue S tudies

________________________________ ______________________________ 58

3.2.4. Uncertainties and Limitations for this Exposure Assessment

________________________________ 58

3.2.4.1. Limitations In Knowledge Of Actual Use P atterns

________________________________ ___ 58

3.2.4.2. Variability In Sulfometuron Environmental Persistence

_______________________________ 59

3.2.4.3. Exposure To Sulfometuron Methyl Degradates

________________________________ _____ 59

3.3. ECOLOGICAL EFFECTS CHARACTERIZATION

____________________________ 59

### 3 3.3.1. Aquatic Effects Characterization

________________________________ _____________________ 61

3.3.1.1. Freshwater Fish, Acute

________________________________ ________________________ 61

3.3.1.2. Freshwater Invertebrates, Acute

________________________________ _________________ 62

3.3.1.3. Estuarine and marine Fish, Acute

________________________________ ________________ 62

3.3.1.4. Estuarine and marine Invertebrates, Acute

________________________________ _________ 63

3.3.1.5. Freshwater Fish, Chronic

________________________________ ______________________ 64

3.3.1.6. Freshwater Invertebrate, Chronic

________________________________ ________________ 64

3.3.1.7. Aquatic Animal Sublethal Effects: Formulated Product and Degradate Toxicity

___________ 65

3.3.1.8. Field Studies

________________________________ ________________________________ 66

3.3.1.9. Aquatic Plants

________________________________ _______________________________ 67

3.3.2. Terrestrial Effects Characterization

________________________________ ___________________ 68

3.3.2.1. Acute Effects on Birds

________________________________ ________________________ 68

3.3.2.2. Acute Effects on Mammals

________________________________ _____________________ 69

3.3.2.3. Acute Effects on Terrestrial

- phase Amphibians, Reptiles and Beneficial Insects

___________ 70

3.3.2.4. Chronic Effects on Birds

________________________________ _______________________ 70

3.3.2.5. Mammals, Reproductive Effects

________________________________ ________________ 71

3.3.2.6. Terrestrial Animal Sublethal Effects, Formulated Product and Degradation Products

________ 71

3.3.2.7. Field Studies

________________________________ ________________________________ 72

3.3.2.8. Terrestrial Plants

________________________________ _____________________________ 72



### 4. RISK CHARACTERIZATION

________________________________________________ 75

4.1. Risk Estimation

- Integration of Exposure and Effects Data

_______________________ 75

4.1.1. Non

- target Aquatic Animals and Plants

________________________________ ________________ 77

4.1.1.1. Fish and Aquatic Invertebrates

________________________________ __________________ 77

4.1.1.2. Aquatic Plants

________________________________ _______________________________ 78

4.1.2

. Non

- target Terrestrial Animals

________________________________ _______________________ 79

4.1.2.1. Birds, Acute Risks

________________________________ ___________________________ 79

4.1.2.2. Birds, Chronic Risks

________________________________ __________________________ 80

4.1.2.3. Mammals, Acute Risks

________________________________ ________________________ 80

4.1.2.4. Mammals, Chronic Risks

________________________________ ______________________ 81

4.1.2.5. Non

- Target Terr estrial

- phase Amphibians, Reptiles and Terrestrial Invertebrates

___________ 82

4.1.3. Non

- target Terrestrial Plants

________________________________ ________________________ 83

4.1.3.1. Non

- Endange red and Endangered Plant Risks

________________________________ ______ 83

4.1.4. Use of Contaminated Irrigation Waters

________________________________ ________________ 84

4.2. RISK DESCRIPTION

________________________________ ______________________ 85

4.2.1. Risk to Aquatic Animals and Plants

________________________________ ___________________ 85

4.2.1.1. Fish and Aquatic Invertebrates

________________________________ __________________ 85

4.2.1.2. Non

- target Aquatic

- phase Amphibians

________________________________ ____________ 87

4.2.1.3. Aquatic Plants

________________________________ _______________________________ 88

4.2.1.4. Aquatic Toxicity of Sulfometuron Methyl D egradates

________________________________ 89

4.2.2. Risk to Terrestrial Animals

________________________________ __________________________ 92

4.2.2.1. Birds

________________________________ ________________________________ ______ 92

4.2.2.2. Mammals

________________________________ ________________________________ __ 94

4.2.2.3. Non

- target Terrestrial

- phase Amphibians, Reptiles, and Beneficial Insects

________________ 94

4.2.3. Risk to Te rrestrial Plants

________________________________ ___________________________ 94

4.2.3.1. Tier 1 Modeling of Runoff and Spray Drift

________________________________ ________ 94

4.2.3.2. Field and Greenhouse Studies

________________________________ ___________________ 95

4.2.3.3. Contaminated Irrigation Water

________________________________ __________________ 96

4.2.4. Refined Spray Drift Analysis

________________________________ ________________________ 97

4.2.5. Review of Incident Data

________________________________ ____________________________ 99

4.2.6. Overall Ecological Risk Conclusions

________________________________ _________________ 100

4.2.7. Endocrine Effects

________________________________ ________________________________ 101

4.2.8. Federally Threatened and Endangered (Listed) Species

________________________________ ___ 101

### 4 4.2.8.1. Action Area

________________________________ ________________________________ 101

4.2.8.2. Taxonomic Groups Potentially at Risk

________________________________ ___________ 102

4.3. Description of Assumptions, Limitations, Uncertainties, and Data Gaps

____________ 107

4.3.1. Assumptions and Limitations Related to Effects on all Species

_____________________________ 107

4.3.2. Assumptions and Limitations Related to Effects on Aquatic Species

________________________ 109

4.3.3. Assumptions and Limitations Related to Effects on Terrestrial Species

______________________ 109



### 5. Literature Cited

_________________________________________________________ 110

6. APPENDICES

__________________________________________________________ 113

APPENDIX A: Structures and Chemical Names of Sulfometuron methyl Metabolites

_______ 113

APPENDIX B: Enviro nmental Fate Data Requirements

______________________________ 115

APPENDIX C: Ecological Aquatic Exposure Modeling

______________________________ 117

APPENDIX D: Terrplant Spreadsheet

___________________________________________ 125

APPENDIX E: Adverse Ecological Incidents Associated with Sulfometuron Methyl Use

____ 127

APPENDIX F: T

- REX Output

__________________________________________________ 129

APPENDIX G: Modeling of Terrestrial plant Exposure from Contaminated irrigation Water 131

APPENDIX H: Ecological Effects Data Summaries

_________________________________ 133

APPENDIX I; Ecological Effects Data Requirements

________________________________ 146

APPENDIX J: Ecological Effects Studies Rejected by OPP

___________________________ 148

### 5 

## LIST OF TABLES

Table 1. Listed Taxonomic Groups Potentially at Risk from Direct or Indirect Effects of Sulfometuron Methyl Application for Vegetative Management Throughout the U .S.

.................. 12 Table 2. Nature and product chemistry of the chemical stressor

- Sulfometuron methyl.

............. 15 Table 3. Taxonomic Groups, Test Species and Acute Toxicity Classification for Assessing Ecological Risks of Sulfometuron Methyl to Non

- target Organisms.

................................ ........... 18 Table 4. Measures of Ecological Effects and Exposure for Sulfometu ron Methyl

....................... 26 Table 5. Permitted application methods for sulfometuron methyl, DuPont Products

.................... 28 Table 6. Permitted application methods for sulfometuron methyl, Vegetation Management LLC

Products

................................ ................................ ................................ ................................ .......... 28 Table 7. States with high sulfometuron usage (based upon DuPont sales data, 2001

- 2004).

....... 28 Table 8. Annual usage of sulfometuron methyl in the US by use site.

................................ ......... 2 9 Table 9. Sulfometuron application rate ranges by product label and use site.

.............................. 30 Table 10. Key results of sulfometuron methyl environmental fates studies.

................................ . 35 Table 11. Models Used to Estimate Exposure Concentrati ons for Aquatic Ecosystem.

............... 45 Table 12. Aquatic exposure with PRZM

– EXAMS: Modeling scenarios and representative usage

pattern summary.

................................ ................................ ................................ ............................ 47 Table 13. PRZM/EXAMS input parameters for modeling (Aquatic ecological EECs).

.............. 47 Table 14. Estimated environmental concentrations ( μ g/L) for aquatic exposure to parent

sulfometur on methyl: scenario

- specific results from PRZM

- EXAMS modeling.

......................... 50 Table 15. Sulfometuron methyl surface water EECs used in aquatic risk assessment.

................ 52 Table 16. Estimated concentrations of sulfometuron methyl in ground water (SCI

- GROW inputs and results).

................................ ................................ ................................ ................................ .... 52 Table 17. Unadjusted Dietary Terrestrial EECs for Birds and Mammals Following Sulfometuron Methyl Spray Application For Non

- Crop Vegetative Management.

................................ ............. 54 Table 18. EECs for Terrestrial Plants Located Adjacent to Sulfometuron Methyl (aerial and

grou nd spray application) Treated Sites.

................................ ................................ ........................ 55 Table 19. Selected AgDRIFT inputs for high

- end exposure from aerial applications of sulfometuron methyl using best management practices.

................................ ................................ 56 Table 20. Estimated percentage of sulfometuron methyl spray drift from ground or aerial applications at various distances from a treated field.

................................ ................................ .... 57 Table 21. Estimated amount of sulfometuron methyl spray drift from ground or aerial applications at various distances from a field treated with the maximum label ed rate of 0.375 lb

ai/A.

................................ ................................ ................................ ................................ ................ 58 Table 22. The Most Sensitive Endpoints Used In The Sulfometuron Methyl Screening

- Level

Risk Estimation.

................................ ................................ ................................ ............................. 61 Table 23. Freshwater Fish Acute Toxicity of Sulfometuron Methyl.

................................ ........... 62 Table 24. Freshwater Invertebrate Acute Toxicity of Sulfometuron Methyl.

............................... 62 Table 25. Estuarine/Marine Fish Acute Toxicity of Sulfom eturon Methyl.

................................ . 63 Table 26. Freshwater Invertebrate Acute Toxicity of Sulfometuron Methyl.

............................... 64 Table 27. Freshwater Aquatic Inv ertebrate Chronic Toxicity for Sulfometuron Methyl.

............ 65

Table 28. Non

- target Aquatic Plant Toxicity for Sulfometuron Methyl.

................................ ...... 68 Table 29. Avian Acute Oral Toxicity for Sulfometuron Methyl.

................................ .................. 69 Table 30. Avian Subacute Dietary Studies for Sulfometuron Methyl.

................................ ......... 69

### 6 Table 31. Mammalian Acute Toxicity for Sulfometuron Methyl.

................................ ................ 70

Table 32. Non

- Target Insects

- Acute Contact Toxicity for Sulfometuron Methyl.

..................... 70 Table 33. Mammalian Developmental Toxicity of Sulfometuron Methyl .

................................ .. 71 Table 34. Mammalian Acute Toxicity to Sulfometuron Methyl in Formulated Product: DPX

T5486

- 87

................................ ................................ ................................ ................................ ........ 72 Table 35. Summary of Most Sensitive Tier II Terrestrial Non

- target Plant Seedling Emergence and Vegetative Vigor Toxicity Data for Sulfometuron Methyl.

................................ .................... 74 Table 36. Risk Presumptions for Aquatic Animals.

................................ ................................ ...... 76 Table 37. Risk Presumptions for Terrestrial Animals.

................................ ................................ .. 76 Table 38. Risk Presumptions for Plants.

................................ ................................ ....................... 76 Table 39. Endpoints Used for Estimating Risks of Sulfometuron Methyl to Aquatic Animals and

Plants.

................................ ................................ ................................ ................................ ............. 77 Table 40. Summary of Acute Aquatic Plant Risk Quotients for Rights of Way Uses.

................. 78 Table 41. Endpoints Used for Estimating Risks of Sulfometuron Methyl to T errestrial Animals.

................................ ................................ ................................ ................................ ........................ 79 Table 42. Upper Bound Kenaga, Acute Avian Dose

- Based Risk Quotients (Bounding Analysis Only).

................................ ................................ ................................ ................................ .............. 80

Table 4 3. Upper Bound Kenaga, Subacute Dietary

- Based Risk Quotients (Bounding Analysis Only).

................................ ................................ ................................ ................................ .............. 80 Table 44. Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients (Bounding Analysis Only).

................................ ................................ ................................ ............................... 81 Table 45. Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk Quotients.

................... 81 Table 46. Upper Bound Kenaga, Chronic Mammalia n Dietary

- Based Risk Quotients

................ 82 Table 47. Summary of Selected Endpoints from Terrestrial Plant Toxicity Studies of Sulfometuron Methyl

................................ ................................ ................................ ..................... 83 Table 48. RQ Values For Plants In Dry And Semi

- Aquatic Areas Exposed To Sulfometuron Methyl Through Runoff And/Or Spray Drift.

................................ ................................ ................ 83 Table 49. Risk Quotients for Non

- target and End angered Plants, Resulting From Exposure to Sulfometuron Methyl in Irrigation Water

................................ ................................ ...................... 84 Table 50. Toxicity of sulfometuron methyl to the African clawed frog from a study by Fort et al. (1999).

................................ ................................ ................................ ................................ ............ 88

Table 51. ECOSAR

- predicted toxicity values for major degradates of sulfometuron methyl.

..... 90

Table 52. Risks to Terrestrial Plants from Spray Drift According to Distance Downwind, Application Method, and Drift Exposure Conditions

................................ ................................ .... 97 Table 53. Listed Taxonomic Groups Potentially at Risk from Direct or Indirect Effe cts of Sulfometuron Methyl Application for Vegetative Management Throughout the U.S.

................ 106

### 7 

## LIST OF FIGURES

Figure 1. Conceptual model for sulfometuron methyl fate an d effects in aquatic ecosystems.

..... 22 Figure 2. Conceptual model for sulfometuron methyl fate and effects in terrestrial ecosystems.

. 23 Figure 3. Chronic Toxicity of Sulfonylurea Herbicides to Freshwater Fish

................................ .. 86 Figure 4. Chronic Avian Toxicity of Sulfonylurea Herbicides

................................ ...................... 93

### 8 

## 1. EXECUTIVE SU MMARY

1.1. Nature of Chemical Stressor

Sulfometuron methyl, (2

- [[[[(4,6

- Dimethyl

- 2

- pyrimidinyl) amino] carbonyl] amino] sulfonyl] benzoic acid, methyl ester ), is a broad

- spectrum p re

- and p ost

- emergence herbicide that is

curren tly registered for weed control in forestry and non

- food crop situations , including vegetative management in right of ways and railroads. It is used to control a variety of broad

- leaf weeds and grasses. Similar to other sulfonylurea herbicides, the mode of action of sulfometuron methyl involves inhibiting the activity of the enzyme acetolactate synthase (ALS), which in turn inhibits the synthesis of selected amino acids that are required for cell proliferation in plants.

Sulfometuron methyl is formulat ed as a water dispersible granul e (WDG) and applied using a variety of methods including helicopter, fixed

- wing aircraft, ground spray (boom and backpack) and spot treatment. It is generally applied once per year for non

- crop areas in years that vegetatio n management is needed

. In some instances (weed escapes) a second application may be made, but all products limit the total quantity of sulfometuron methyl that may be applied (from any source) to 6 ounces of active ingredient per acre per year (0.375 lb a i/A) . Therefore, application rates in general forestry, and for site preparation and/or release in conifer, hardwood and Christmas tree plantations, will vary significantly depending upon the specific purpose of the application and the desirable tree spec ies. In forestry, uses can be similar to plantation sites, but may also include the maintenance of access routes and fire breaks. It is further noted that use rates can also vary with climate and soil type

.



## 1.2. Conclusions

- Exposure Characterization

1.2. 1. Environmental Fate

a. Persistence

Sulfometuron methyl is expected to be relatively persistent in soil and water (half

- life ranging from about 2 weeks to 6 months, depending on environmental conditions). The persistence of

s ulfometuron is likely to b e lowest under low pH conditions in soil and water.

Abiotic and microbially

- mediated hydrolysis / degradation are both major route s of

transformation of sulfomet uron methyl in water, soil, and water

- sediment systems. The degradation in soil and water appe ars to be enhanced in the presence of an active microbial population (aerobic and anaerobic degradation both proceed more slowly under sterile conditions).

### 9 b. Transport and Bioaccumulation

Sulfometuron has a low potential to volatilize from soil or water or to bioaccumulate. Off

- site transport of sulfometuron methyl occurs via spray drift, and the wind erosion of soil particulates containing sulfometuron methyl.

Sulfomet uron methyl does not sorb strongly to soils and has the potential to leach to grou nd water and/or reach surface water during runoff events. Sulfometuron methyl is a weak acid (pKa of

5.2 ). The mobility of sulfometuron methyl is expected to increase with increasing pH based upon

available data submitted to EPA for related sulfonylurea herbicides and published studies ; however direct, definitive evidence of this for sulfometuron methyl has not been produced.



## 1.3. Conclusions

- Effects Characterization

Available acute toxicity data for freshwater fish and invertebrates indicate that sulfome turon methyl is practically non

- toxic on an acute exposure basis. All EC 50 

### s / LC 50 

### s are >100 mg/L. For marine and estuarine fish and invertebrates, available acute toxicity data indicate that sulfometuron methyl is at most slightly toxic on an acute exposu re basis (EC 50 

### / LC 50 

### s range from >38 to >45 mg ai/L).

No acceptable studies were available for evaluating the effects of chronic exposure to sulfometuron methyl on freshwater, estuarine or marine fish. Chronic NOAEC for freshwater fish

was therefore esti mated to be >21 mg ai/L using an acute

- chronic ratio derived from flazasulfuron, another sulfonylurea herbicide with the same mode of action

. The aquatic

invertebrate NOAEC i s 97 mg ai/L (highest concentration tested) at which survival and reproduction we re not significantly different from controls. Estimated chronic effects for estuarine/marine fish and invertebrates are uncertain because no chronic data on saltwater species were submitted by the registrant. However, comparison of freshwater and saltwat er species acute toxicity values does not suggest considerable differences in sensitivity between freshwater and saltwater species.

Aquatic vascular plants a re more sensitive than any of the aquatic nonvascular plants tested. The

14

- day EC 50 

### and NOAEC fo r the freshwater vascular plant (duckweed) for frond count (the most sensitive endpoint tested) was 0.48 and 0.21 μg/L, respectively. The green

- algae was the most

sensitive non

- vascular plant tested with EC 50 

### and NOAEC values of 4.6 and 0.63 μg/L

, respect ively, based on cell density.

Sulfometuron methyl is practically non

- toxic to birds (LD 50 

### > 4,650 mg/kg

- bw; LC 50 

### >4,600 mg/kg

- diet), mammals ( LD 50 

### > 5000 mg/kg

- bw), and bees ( LD 50 

### >100 ug/bee) on an acute toxicity basis. No sublethal effects were observe d from the acute toxicity studies of birds and mammals. Data on reproductive effects of sulfometuron methyl to birds were not available. Acceptable data on mammalian reproductive effects were also not available. Data on the effects of gestational exposu re to sulfometuron methyl were available from a rabbit developmental toxicity study which resulted in a NOAEL of 300 mg ai/kg

- bw/d (highest dose tested)

.

### 10 Seedling emergence and vegetative vigor studies in terrestrial plants were submitted by the regis trant

. Based on the most sensitive species and endpoints reported, sulfometuron methyl i s slightly more toxic to terrestrial plants in the vegetative vigor study compared to seedling emergence. The seedling emergence EC25 for the most sensitive dicot (su gar beet) and monocot (sorghum) are 3.2 x 10 - 5 

### and 1.9 x 10 - 4 

### lb ai/A, respectively. The vegetative vigor EC25 for the

most sensitive dicot (soybean) and monocot (corn) are 1.8 x 10 - 5 

### and 3.7 x 10 - 5 

### lb ai/A, respectively. The guideline seedling emerge nce and vegetative vigor studies reported non

- lethal

effects of sulfometuron methyl exposure on plants such as chlorosis, growth retardation, necrosis, and unusual pigmentation.



## 1.4. Potential Risks to Non

- target Animals and Plants

Potential risks to aquat ic and terrestrial plants are indicated by this risk assessment, as LOCs are widely exceeded for terrestrial and aquatic plants at the maximum application rate

. For terrestrial plants, RQs calculated at the edge of a treated field resulting from spray dri ft alone were as high as 22,000 for non

- endangered plants and 400,000 for endangered plants. Terrestrial plant RQs dropped substantially 50 ft from the edge of a treated field but still exceeded Agency LOCs at 900 ft (700 to 12,000 for non

- endangered and endangered plants, respectively. The impact of spray drift practices recommended by the label did not reduce RQ values below LOCs for terrestrial plants (RQs were reduced only by a factor of three compared to ‘high end’ exposure assumptions). Potential r isks to terrestrial plants from irrigation with sulfometuron methyl contaminated surface water were also evident (RQ = 3.9 and 71 for non

- endangered and endangered species, respectively).

The RQ value s for aquatic plants exceeded LOCs and ranged from 49 to 148 for endangered nonvascular and vascular plants, respectively and from 6.7 to 65 for non

- endangered nonvascular and vascular plants, respectively

. Based on comparisons of adverse effect levels with longer

- term average EECs predicted from the PRZM/E XAMS model (e.g., 90

- d EEC of 16 μg/L), the ability of duckweed and other vascular aquatic plants to recover from predicted long

- term exposure concentrations of sulfometuron methyl in adjacent, static aquatic systems appears unlikely under the exposure conditi ons modeled.

Although u se of ‘typical’ application rates would result in RQs of up to one order of magnitude lower than the maximum application rate, RQs would still exceed Agency LOCs for terrestrial and aquatic plants. The conclusion of potential ris ks to aquatic and terrestrial plants from sulfometuron methyl application in non

- crop uses is consistent with findings from other sulfonylurea herbicide risk assessments and ecological incident reports associated with sulfometuron methyl usage. Wind

- drive n erosion and drift of sulfometuron was implicated in one of the largest ecological incidents reported following its application (as Oust) to fire

- damaged rangeland (crop damage estimated at $72 million). Although LOCs were not exceeded for

terrestrial or aquatic animals, animals that depend on plants for survival or reproduction (presumably all taxa at the screening level) are also potentially at risk from indirect effects resulting from direct effects of sulfometuron to aquatic or terrestrial plants.

### 11 An ana lysis of the of the effects of various spray drift management practices (using the AgDRIFT model; see http://www.agdrift.com/AgDRIFt2/DownloadAgDrift2_0.htm ) demonstrates that a

s ubstantial reduction in off

- site exposure is possible with the implementation of application

methods known to reduce drift

. Droplet size is important in controlling spray drift. Using larger droplet sizes, such as coarse or extremely coarse spraying, redu ces the downwind d rift to adjacent

areas compared to when medium or fine spraying is used. Thus, this assessment suggests that by placing drift management practices on labels such as specifying coarse or extremely coarse sprays (based on the ASAE standard) , risks to non

- target plants would not extend as far from the treated

area. Reducing boom height during application and applying when wind speeds are between 3 and 10 mph are other examples of practices that control drift . Many of these practices are

reco mmended, but not required by the product labels (see Section 3.2.3.1 and 4.2.3.1 for more

details )

.

In addition, in regions where sulfometuron methyl has been used r egularly, sulfometuron methyl concentrations in surface irrigation water may result in damage to agricultural crops that are

sensitive to sulfometuron methyl

.



## 1.5. C onclusions

- Endangered Species

Direct effects LOCs were exceeded for endangered aquatic and terrestrial plants. In addition, there is potential for indirect effects to all animal taxa that depend on plants for survival, growth, or reproduction, which are presumably all animal taxa at the screening level. Therefore, listed species from all taxono mic groups are potentially at risk from sulfometuron methyl uses.

The results of this screening risk assessment indicate that direct effects to plant species could present an indirect risk at the higher levels of organization (i.e. population, trophic le vel, community, and ecosystem). The distance from the treated area that risks could extend is greater

than 900 ft, which is the maximum distance that EFED’s Tier 2 spray drift model (A gDRIFT ; information on this model is available at http://www.agdrift.com/AgDRIFt2/DownloadAgDrift2_0.htm 

### )

can estimate. Due to the wide geographic distribution of potential application areas for non

- crop uses of sulfometuron methyl, an action area for e ndangered species cannot be defined at this time

for this assessment. A model is available for extending predictions of deposition from spray drift beyond 1000 feet (AgDISP with Gaussian extension ; see Teske and Thistle, 2004 ; and Thistle et al., 2005 ). However, the trends observed in modeling of drift out to 900 feet downwind from treated areas imply that potential risks to the most sensitive species (non

- target terrestrial plants) are likely to extend well beyond 1000 feet given the currently available information for our Tier II

assessment

. Field studies are not available to quantify actual risk to plant and animal communities in forest/edge and wetland/riparian habitats. However, in terrestrial and shallow

- water aquatic communities, plants are the pri mary producers upon which the succeeding trophic levels depend. If the available plant material is impacted due to the effects of sulfometuron methyl , this may have negative effects not only on the herbivores, but also throughout the food chain. Also,

de pending on the severity of impacts to the plant communities [i.e., forests, wetlands, ecotones (edge and riparian habitats)], community assemblages and ecosystem stability may be altered (i.e. reduced bird populations in edge habitats; reduced riparian veg etation resulting in increased light

### 12 penetration and temperature in aquatic habitats, loss of cover and food for fish). In addition, riparian vegetation, which is a significant component of the food supply for aquatic herbivores and detritivores provides habitat (i.e. leaf packs, materials for case

- building for invertebrates) may

also be affected.

The following table provides listed taxonomic groups that may be at risk from direct or indirect effects due to applications of sulfometuron methyl for vegetati ve management uses nationwide.

Table 1

. Listed Taxonomic Groups Potential ly at Risk from Direct or Indirect Effects of Sulfometuron Methyl Application for Vegetative Management Throughout the U.S.

Listed Taxon Direct

Effects Ba sis for Direct Effects Concern Indirect

Effects Basis for Indirect Effects Concern

Terrestrial and

Semi

- Aquatic

Plants

– monocots and

dicots Yes The endangered and non

- endangered species LOC s are exceeded for terrestrial plants. Yes Potential concerns fr om shifts in plant community structure and function due to from selective impacts on plant species.

Terrestrial

Invertebrates No Sulfometuron methyl is practically nontoxic to honeybees, suggesting no direct effect concerns for terrestrial

invertebrates. Yes Potential concerns for terrestrial invertebrates that use plants for habitat, feeding, or cover requirements.

Birds and Reptiles 1 No The LOC is not exceeded Yes Potential concerns for birds and reptiles that use plants for habitat, feeding, or cover requirements.

Terrestrial

- phase Amphibians (1) No The LOC is not exceeded Yes Potential concerns for terrestrial

- phase amphibians that use plants for habitat, feeding, or cover requirements.

Mammals No The LOC is not exceeded Yes Potential concerns fo r mammals that use plants for habitat, feeding, or cover requirements. Aquatic Vascular

Plants and

Nonvascular

Plants Yes The endangered and non

- endangered species LOC s are exceeded for aquatic

vascular and nonvascular plants. Yes Potential concerns fro m shifts in plant community structure and function due to from selective impacts on plant species.

Freshwater and

Marine/Estuarine fish and Aquatic

phase Amphibians (2) No The LOC is not exceeded Yes Potential concerns for fish and aquatic

- phase amphibians that use plants for habitat, feeding, or cover requirements.

Freshwater and

Marine/Estuarine

Crustaceans No The LOC is not exceeded Yes Potential concerns for crustaceans that use plants for habitat, feeding, or cover requirements.

Mollusks No The LO C is not exceeded Yes Potential concerns for mollusks that use plants for habitat, feeding, or cover requirements.

(1) Birds are used as surrogate species for terrestrial

- phase amphibians and reptiles; therefore, potential direct and indirect effects to endangered avian,

terrestrial

- phase amphibians and reptilian species are considered equivalent. (2) Fish are used as a surrogate for aquatic phase amphibians; therefore, potential direct and indirect effects to endangered fis h and aquatic

- phase amphibian species are considered equivalent.

### 13 

## 1.6. Identification of Uncertainties and Their Impact on the

Risk Assessment

1.6.1. Environmental Fate and Exposure

Limitations In Knowledge Of Actual Use Patterns

**•** Specific regions of use are not known. T he use pattern of sulfo meturon methyl does not lend itself to easy characterization geographically: There are a variety of vegetation management uses on sites that are less clearly defined than agricultural crops and have disjoint or unusual treatment area configurations (e.g., as with rights of way and railroad uses, or industrial site grounds)

**•** Practical limits on usage rates long

- term at particular sites may different fr om legally allowable use levels (e.g., usage is highly unlikely to occur every year at a particular site

even though this is allowable under the label language)

Variability In Sulfometuron Environmental Persistence

**•** Sulfometuron methyl persistence is s ignificantly affected by soil or water chemistry and

may not always be easy to predict from typically available s oil / water property data alone

. A clearer picture of the range of variability in sulfometuron methyl persistence in the

environment would require environmental fate studies on a greater variety of soils / waters / sediments with a greater range of pH lev els and other soil properties. This is particularly true for the aerobic soil and anaerobic aquatic metabolism studies

Insufficient Data And Methods Are Currently Available For Predicting Exposure To

S ulfometuron Methyl Degradates.

**•** The total residues of sulfometuron methyl including environmentally significant degradates were not modeled with PRZM

- EXAMS because of data and model limitations.

**•** Limitations in environmental fate data for the degradates constrain s the modeling. The data on individual degradate s
, environmental persistence and mobility is insufficient to model each compound separately. Furthermore, total residue modeling with the currently

available receiv ing water body assumes residues concentrate in that body (pond) since:

o available data requ ire assumptions of total stability of sulfometuron total residues (because insufficient decline data are available from the laboratory studies) ;

o The existing surface water exposure scenario assumes these stable residues do not migrate from the pond and sim ply concentrate in the pond as applications of sulfometuron methyl are applied to the watershed.

**•** Data on sulfometuron effects on plants implies that low levels of sulfometuron methyl in soil and water may adversely affect the growth of sensitive terrestria l or aquatic species. For some sulfonylurea herbicides concentrations below 1ug/L in water or 1ug/kg in soil have been shown to affect the growth of sensitive plant species.

### 14 1.6.2. Ecological Effects

**•** Indirect Effects to Animals. In this screening

- level risk ass essment, aquatic and terrestrial plants were found to be at potential risk from the modeled sulfometuron methyl uses. Therefore, the potential exists for indirect effects on aquatic and terrestrial animals that depend on plants adversely affected by expos ure to sulfometuron methyl. These indirect effects on aquatic and terrestrial animals could be expressed at the organism, population, community or ecosystem level of organization. No acceptable field studies

were available to quantif y the indirect effect s of sulfometuron methyl to aquatic or terrestrial animals. Because risks associated with indirect effects on aquatic and terrestrial animals could not be assessed, ecological risks to animals could be underestimated to the

extent that such indirect effec ts occur.

**•** Ecological Risk of Sulfometuron Methyl Degradation Products. In this screening level ecological risk assessment, ecological risks associated with the major degradates of sulfometuron methyl ( e.g., pyrimidine amine, pyrimidine

- ol, saccharin , s ulfonamide ) could not be reliably assessed. Reasons for this limitation are two

- fold. First, the vastly different chemistries of the degradates (and likely correspondent differences in toxicological profiles) essentially precluded a meaningful applicatio n of the total residue approach in the exposure assessment. Second, acceptable ecotoxicity data we re not available for the degradates. Because the chemical structure and environmental behavior of the major degradates differ substantially from the parent molecule (i.e., degradation involves cleavage of the sulfonylurea bridge, essentially splitting the molecule in half), it could not be assumed with reasonable confidence that the degradates are equivalent in toxicity to the parent compound.

**•** Toxicity Dat a Quality and Data Gaps. Acceptable or supplemental toxicity data were not available for assessing the chronic toxicity of sulfometuron methyl to freshwater fish or the reproductive toxicity to birds and mammals. A bounding analysis suggests that the

risk assessment results are not likely to be sensitive to the lack of chronic toxicity data for fish, given the large difference between EECs and extrapolated toxicity limits. For mammals, the NOAEL of 300 mg ai/kg

- bw/d was used from a developmental toxicity study to rabbits. While providing some information on the effect of sulfometuron methyl on mammalian development during gestational exposure, results from this study do not capture the potential effects of sulfometuron methyl on reproductive endpoints incl uding courtship, mating, sex ratios and offspring survival, growth and development. Diet and

dose

- based RQs based on this NOAEL were 0.01 or lower, thus indicating that reproductive toxicity would have to occur at exposures that are approximately two orde rs of magnitude lower than developmental effects.

**•** Vascular Plant Reproduction . Terrestrial and aquatic plants appear most sensitive to sulfometuron methyl exposure. While toxicity data were available for endpoints related to systemic growth, seedling em ergence and visual injury, these guideline studies are not designed to capture reproductive endpoints. There is some evidence to suggest plant reproduction may be affected by sulfonylurea herbicides at levels below effects on

### 15 vegetative growth or visual i njury (Fletcher et al., 1993). Therefore, to the extent that terrestrial and aquatic plant reproduction are more sensitive to sulfometuron methyl than growth endpoints, risks to aquatic and terrestrial plants may be underestimated in this risk

assessment.



## 2. P ROBLEM FORMULATION

The purpose of problem formulation is to provide the foundation for the ecological risk assessment being conducted for sulfometuron methyl. It sets the objectives for the risk assessment, evaluates the nature of the problem, and p rovides a plan for analyzing the data and characterizing the risk (US EPA, 1998).



## 2.1. Nature of the Regulatory Action

Under section 4 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), EPA is reevaluating existing pesticides to ensure that they meet current scientific and regulatory

standards. With this document, EPA has completed its baseline environmental fate and ecological effects risk assessment to support a Reregistration Eligibility Decision (RED) for the

herbicide , sulfometuron met hyl

. Sulfometuron methyl was first registered for use in 1982 by E.I. du Pont de Nemours and Company (DuPont); all registered uses then and now have been for vegetation control in non

- agricultural areas. Currently, both DuPont and Vegetation Management, LLC have registered end

- use products containing sulfometuron methyl.



## 2.2. Stressor Source and Distribution

2.2.1. Nature of the Chemical Stressor

Sulfometuron methyl, a broad

- spectrum p re

- and p ost

- emergence herbicide, is currently registered

for weed control in forestry and non

- food crop situations , including vegetative management in right s

- of

- ways and railroads

. It is used to control a variety of broad

- leaf weeds and grasses

. Similar to other sulfonylurea herbicides, the mode of action of s ulfometuron methyl i nvolves inhibiting the activity of the en zyme acetolactate synthase (ALS) , which in turn inhibits the synthes i s of selected amino acids that are required for cell proliferation in plants

. A brief summary of the product chemistry data on sulfometuron methy l is provided in Table 2

.

Table 2

. Nature and product chemistry of the chemical stressor

- Sulfometuron methyl.

Common name Sulfometuron methyl

IUPAC Chemical Name 2

- (4,6

- Dimethylpyrimidin

- 2

- ylcarbamoy lsulfamoyl) benzoic acid, methyl ester

OR

2

- [3

- (4,6

- dimethylpyrimidin

- 2

- yl)ureidosulfonyl] benzoic acid,

### 16 methyl ester

CAS Chemical Name 2

- [[[[(4,6

- Dimethyl

- 2

- pyrimidinyl) amino] carbonyl] amino] sulfonyl] benzoic acid, methyl ester

Structure

O O C H 3

S

O O

N H

N

O H

N N C H 3

C H 3 

### Pesticide type Herbicide

Chemical class S ulfonylurea herbicide

CAS number 74222

- 97

- 2 Empirical formula C 15 

### H 16 

### N 4 

### S O 5 

### Molecular Mass (g/mol) 364.38 Vapor pressure at 20 o 

### C 5.4 x10 - 16 

### Torr Henry’s Law Constant at

20 o 

### C (atm m3/mol ) 1.1 x 10 - 1 8 

### , calculated

from va por pressure

Solubility in water (mg/L)at

20 0 

### C pH 5 buffer...... 6.42 ppm pH 7 buffer ...... 244 ppm pH 8.6 buffer.. 12

, 5 00 ppm Log K
ow 

### pH 5 = 1.03 pH 7 =

- 0.46 pH 9 =

- 1.87 pKa at 25°C 5.2

Sulfometuron met h yl may be persistent and mobile and may ha ve a significant impact on ground

water and surface water resources

. Degradation half

- lives in soil and water range from about 2

weeks to 6 months due to aerobic metabolism, anaerobic aquatic, aerobic aquatic, and hydrolysis (except in acidic solution the half

- life is only about 1 week). Parent persistence is similar under anaerobic and aerobic conditions. Complete d egradation / mineralization is more rapid under

aerobic conditions and is generally enhanced substantially when microbes are present . The prim ary route of degradation is by the following pathway involving cleavage of the sulfonylurea bridge:

(1) Hydrolytic cleavage generating a sulfonamide plus the amino pyrimidine (resulting in elimination of a carbon dioxide molecule) (2) The sulfonamide (produced by hydrolysis of the sulfonylurea) is further cyclized with the carbomethoxy group in the ortho position, yielding a saccharin.

Degradation by this same pathway occurs at a slower rate under sterile conditions.

### 17 Sulfometuron methyl is considered “mobile” ac cording to the classification system of the Food and Agricultural Organization, Agriculture and Consumer Protection Department’s “Assessing Soil Contamination: A Reference Manual” (see: http ://www.fao.org/DOCREP/003/X2570E/X2570E06.htm ). Sulfometuron methyl mobility is

“ high ” to “ very high ” based upon the classification system of McCall et al. (1981; see also http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.htm for a description). Soil persistence is sufficient such that vulnerable aquifers may be expected to be impacted. Sulfometuron methyl c oncentrations in surface waters may be relatively high when significant runoff events occur after application and / or spray drift to water bodies in close proximity to the

treatment area occurs.

2.2.2. Overview of Pesticide Usage

Sulfometuron methyl is formulated as a water dispersible granul e (WDG) and applied using a variety of methods including helicopter, fixed

- wing aircraft, ground spray (boom and backpack) and spot treatment. Sulfometuron methyl is registered for non

- crop agricultural and vegetative

management uses throughout the United States. T he most significant uses include forestry and tree nurseries (weed control to promote seedling growth), vegetative management in utility right

of

- ways , roadsides and railroads, industrial sites ( e.g., to maintain bare ground in utility

substation s ), under asphalt and concrete prior to paving and for broadleaf weed control in unimproved turf and on non

- crop restoration sites. The highest use areas are believed to be in

Pacific Coast states and the southeastern United States.

The application rates and frequency varies widely depending on use and the specific pest situation, but all uses are restricted to an annual maximum application of 6 oz ai ./acre.



## 2.3. Receptors

2.3.1. Aquatic and Terrestrial Effects

The receptor is the biological entity that is exposed to the stressor (US EPA, 1998). Aquatic receptors potentially at risk include (but are not limited to): fish, amphibians, invertebrates (e.g., aquatic insects, mollusks, crustaceans, and worms ), vascular plants and algae. Terrestrial receptors potential ly at risk include (but are not limited to): birds, mammals, reptiles, amphibians, terrestrial invertebrates (e.g., insects, worms, arachnids), and plants.

Consistent with the process described in the Overview Document (US EPA, 2004), this risk

assessment uses a surrogate species approach in its evaluation of sulfometuron methyl

. T oxicological data generated from surrogate test species, that are intended to be representative of broad taxonomic groups, are used to extrapolate to poten tial effects on a variety of species (receptors) included under these taxonomic groupings.

### 18 A cute and chronic toxicity data from studies submitted by pesticide registrants along with the available open literature are used to evaluate potential direct eff ects of sulfometuron methyl to the aquatic and terrestrial receptors identified in this section. This includes toxicity data on the technical grade active ingredient, degradates, and when available, formulated products (e.g. “Six

Pack” studies). The open literature studies are identified through EPA’s ECOTOX database ( http://cfpub.epa.gov/ecotox/ ), which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of sulfometuron methyl on biotic communities due to loss of species that are sensitive to the chemical and changes in structure and

functi onal characteristics of the affected communities.

Table 3 provide s a summary of the taxonomic groups and the surrogate species tested to help understand potential acute ecological effects of pesticides to these non

- target taxonomic groups.

In addition, the table provides a preliminary overview of the potential acute toxicity of sulfometuron methyl by providing the acute toxicity classifications. Based on a preliminary review of the ecological effect data, sulfo meturon methyl is , for the most part, practically non

toxic to freshwater fish, freshwater invertebrates, birds, mammals

, and honeybees under acute exposure conditions. Acute toxicity to estuarine/marine fish and invertebrates was not observed at the high est concentrations tested, which fell into the slightly toxic category

. Under chronic exposure conditions, the sulfometuron methyl inhibited reproduction of both fathead minnow ( Pimephales promelas ) and water fleas ( Daphnia magna ) . Acceptable chronic repr oductive toxicity data were not available for birds or mammals

. As expected, a quatic and terrestrial plants show the greatest sensitivity to the parent compound

.

Major environmental degradates of sulfometuron methyl most commonly include: the

sulfometuro n sulfonamide, the sulfometuron pyrimidine amine, and saccharin; other degradates occur less commonly ( see Table 10 and A PPENDIX A : Structures and Chemical Names of Sulfometuron methyl Meta bolites ). Other than deesterification from sulfometuron methyl to the free acid, the degradates are formed from cleavage of the sulfonyl urea bridge between the phenyl and pyrimidine ring structures. The latter compounds are not expected to be substantia lly phytotoxic, however, information is requested from the registrant to confirm this.

Table 3 . Taxonomic Groups, Test Species and Acute Toxicity Classification for Assessing Ecological Risks of Sulfometuron Methyl to Non

- target Organisms.

Taxonomic Group Example(s) of Surrogate Species Acute Toxicity Classification

Birds 1 Mallard duck ( Anas platyrhynchos ) Bobwhite quail ( Colinus virginianus ) Practically non

- toxic

Mammals Laboratory rat ( Rattus norvegicus ) Practically non

- toxic

Insects Honey bee ( Apis mellifera L. ) Practically non

- toxic

Freshwater fish 2 Bluegill sunfish ( Lep omis macrochirus ) Rainbow trout ( Oncorhynchus mykiss ) Practically non

- toxic Practically non

- toxic

Freshwater invertebrates Water flea ( Daphnia magna ) Practically non

- toxic

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus) > Slightly toxic 4

Estuarine/marine

invertebrates Mysid shrimp ( Mysidopsis bahia ) Eastern oyster ( Crassostrea virginica) > Slightly toxic 4

> Slightly toxic 4

### 19 Taxonomic Group Example(s) of Surrogate Species Acute Toxicity Classification

Terr estrial plants 3 Monocots

– corn ( Zea mays )

Dicots

– soybean ( Glycine max ) Not classified

Aquatic plants and algae Duckweed ( Lemna gibba ) Green algae ( Selenastrum capricornutum )

B luegreen a lgae ( Anab a ena flos

- aquae) Diatom ( Navicula pelliculosa) Not classified

1 In absence of data, b irds are used as surrogates for terrestrial

- phase amphibians and reptiles.

2 In absence of data, f reshwater fish may be surrogates for aq uatic

- phase amphibians.

3 Data required for 4 species of monocots from 2 families (must include corn) and 6 species of dicots from 4 families (must include soybean).

4 Toxicity endpoint was greater than the highest concentration tested, which fell in the slightly toxic category

.



### 2.3.2. Ecosystems at Risk

The ecosystems at potential risk from sulfometuron methyl are extensive in scope due to the wide geographic distribution of potential sulfometuron methyl application sites. A s a result

, it is not possible to i dentify specific ecosystems at risk during the development of this baseline risk assessment. However, in general terms, terrestrial ecosystems potentially at risk could include the treatment areas directly and adjacent areas that may receive herbicide dri ft or runoff. This could

include the treatment area itself as well as other cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats and other uncultivated areas. Within these ecosystems, available tox icity data indicate terrestrial plants are highly sensitive to sulfometuron methyl and thus, they could be directly affected. O rganisms dependent on sensitive

terrestrial plants could be affected indirectly

, which could result in subsequent effects at the community and ecosystem level s . Birds and mammals appear to be much less sensitive to the direct exposure of sulfometuron methyl compared to plants, although they could be affected indirectly to the extent they depend on affected plants for food and habi tat.

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

treat ment area and might include impounded bodies such as ponds, lakes , r eservoirs and wetland

areas , or flowing waterways such as streams and rivers. For uses in coastal areas, aquatic habitat also includes marine ecosystems, including estuaries and salt marshes . Similar to the terrestrial

ecosystems, available toxicity data indicate aquatic plants are highly sensitive to sulfometuron methyl exposure a nd thus could be directly affected. Other organisms dependent on aquatic plants could be affected indirectly. Aquatic animals appear to be much less sensitive to direct exposure to sulfometuron methyl compared to plants, although they could be affected i ndirectly to the extent they depend on affected plants for food and habitat.



## 2.4. 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 (US EPA, 1998). For sulfometuron methyl, the ecological entities may include the following: birds, mammals, freshwater fish and invertebrates, estuarine/marine fish and invertebrates, terrestrial

### 20 plants, insects, and aquatic plants and algae. The attributes for each of these entities may include growth, reproduction, and survival and are discussed further in the Analysis Plan (Section 2.6 )

.



## 2.5. 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 com plete, 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.

A conceptual model is used in this risk assessment to provide a written and visual descri ption of the predicted relationships between sulfometuron methyl, potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: risk hypotheses and a conceptual diagram (US EPA, 19 98).

2.5.1. Risk Hypotheses

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in assessment endpoints) and may be based on theory and logic, empirical data, mathematical models, or probability models (EPA 1998a). For sulf ometuron methyl, the following ecological risk hypothesis is being employed for this baseline risk assessment:

Given persistence and mobility of sulfometuron methyl and some of its degradates

, there is

a likelihood that terrestrial and/or aquatic organism s will be exposed when s ulfometuron methyl is used in accordance with the label . Consequently, considering the mode of action, direct toxicity and potential indirect effects, labeled uses of sulfometuron methyl have the potential to cause adverse effects upon the survival, growth, and reproduction of

non

- target terrestrial and aquatic plants and animals

.

2.5.2. Conceptual Diagram

Based on the iterative process of examining the usage information, fate and effects data, the risk hypothes es described previously, c onceptual diagram s are shown in Figure 1 and Figure 2 for aquatic and terrestrial ecosystems, respectively. These conceptual models illustrate : (1) the most likely stressors/exposure pathways

, and (2) th e organisms that are most relevant and applicable to

this assessment.

T he dominant sources /transport pathways of sulfometuron methyl to aquatic ecosystems include spray drift, runoff and erosion from treated areas to surface waters and aquatic sediments

. Sulfometuron methyl also has the potential to leach to groundwater which can serve as inputs to surface water, although this is not explicitly modeled for ecological effects in this risk assessment

d ue to model ing and data limitations

. Once in surface water and sediments, sulfometuron methyl

may be directly toxic to aquatic vascular plants (rooted macrophytes) and nonvascular plants (algae) via uptake through the roots or cell membrane. Sulfometuron methyl exposure in surface

### 21 water and sediments may al so cause direct toxicity to aquatic animals, although the generally low toxicity to aquatic animals renders this pathway less of a concern compared to aquatic plants.

Indirect effects on aquatic animals via impacts on aquatic plants is also a concern, but is not explicitly modeled in this risk assessment due to model and data limitations.

The dominant sources /transport pathways of sulfometuron methyl to terrestrial ecosystems include direct spray on terrestrial food items, spray drift, runoff and erosion from herbicide treated areas, and leaching to groundwater. Wind

- driven erosion of treated soils is also a potential source of concern, particularly to non

- target plants but is not modeled in this risk assessment due to data and modeling limitations. Vola tilization of sulfometuron methyl is also a potential source of exposure for terrestrial animals via inhalation, but is of less concern given its low volatility and low inhalation toxicity based on mammalian data (MRID 430892

- 03)

. Once sorbed onto food

it ems, terrestrial animals (birds, mammals) may be exposed to sulfometuron methyl via diet and dermal absorption, although its low toxicity to birds and mammals suggest that effects from this exposure pathway are much less likely than effects on terrestrial plants. Adverse effects on non

target terrestrial plants may occur through exposure to herbicide spray drift, contaminated runoff and groundwater, erosion of herbicide treated soil via direct contact and root uptake , and irrigation with contaminated groun d water or surface water sources . Indirect impacts may occur on animals that depend on affected terrestrial plants for food or habitat.

### 22 Figure 1 . Concept ual model for sulfometuron methyl fate and e ffects in aquatic ecosystems.

1 Bold lines and text boxes represent exposure pathways and effects that were assessed quantitatively in this risk

assessment. Dashed lines indicate potential exposure pathways or effects that were not assessed quantitative ly. 

### Sulfometuron Methyl Appli ed To Foliage Via Aerial And Ground Sprays Stressor

Source/ Transport Pathways

Receptor Spray

Drift Runoff /

Erosion Leaching/

Infiltration

Source/ Exposure

Media Surface Water/

Sediment

Exposure

Point

Aquatic

Animals

Attribute

Change Individual Animals Reduced survival,

growth and/or reproduction Vascular Aquatic

Plants Gill/Integument Uptake & Ingestion

Individual Plants

Reduced Survival

and Growth Groundwater

Indirect effects Direct Contact & Root Uptake

Plant Population

Reduced Population Growth Nonvascular Aquatic Plants

### 23 Figure 2 . C onceptual model for sulfometuron methyl fate and effects in terrestrial ecosystems

.

1 Solid lines and text boxes represent exposure pathways and effects that were assessed quantitativ ely in this risk

assessment. Dashed lines indicate potential exposure pathways or effects that were not assessed quantitatively. 

### Sulfometuron methyl applied to foliage via aerial and ground sprays Stressor

Source/ Transport Pathways

Receptor Volatilization

/Wind

Erosion Direct Deposition Spray

Drift Runoff/

Erosion Leaching/

Infiltration

Source/ Exposure

Media Terrestrial Food (foliage, fruits insects) Air/ Soil

Particles

Inhalation/

Dermal Foliage/Soil

Exposure

Point Ingestion

Terrestrial

Animals

Attribute

Change Individual Animals

Reduced surv ival,

growth and/or reproduction Terrestrial

Plants Direct Contact/

Root Uptake

Individual Plants

Reduced Survival

and Growth Groundwater

Indirect effects

### 24 

## 2.6. Analysis Plan

This document characterizes the environmental fate and effects of sulfomet uron methyl to assess

whether existing label uses for reregistration of this compound result in potential risk to non

target organisms above the Agency’s levels of concern (LOCs). Available environmental fate, ecotoxicity, and physicochemical property data were taken from studies submitted previously to

EPA and where available, the open scientific literature. At or near the time of their submission to

EPA , environmental fate and effect studies underwent formal d ata evaluation review (DER) to
determine thei r acceptability relative to published EPA guidelines. For the ecotoxicity data, the

studies and/or DERs were re

- reviewed to ensure that studies met current acceptability guidelines.

For the environmental fate studies

, new data or information or new studi es were submitted in response to Agency reviews of earlier data submissions; most of these new study addendums or replacements for older studies were submitted in the early 1990s but were not previously subject to formal review by the Agency . Any literatu re studies used in this risk assessment were evaluated according to EPA/OPP/EFED review guidelines in place at the time of submission and accepted if deemed scientifically valid; however, test conditions deviate in some ways from the

current OECD Guideline s (See http://www.epa.gov/oppefed1/ecorisk_ders/toera_analysis_exp.htm#WSAN2 and

ht tp://www.oecd.org/department/0,3355,en_2649_34377_1_1_1_1_1,00.html ).

2.6.1. Conclusions from Previous Risk Assessments

No previous environmental fate and ecological risk assessment was available for sulfometuron methyl that was comparable to current OPP pra ctices. However, comprehensive ecological risk

assessments were available from two other Federal sources: US Forest Service ( USDA

, 2004 ) and the Bureau of Land Management ( BLM, 2005 )

. In many cases, the overall methodology and data

used in these assessme nts was similar to that used by OPP, although some differences in the models, interpretation of data, and associated assumptions were evident.

Results from the US Forest Service Ecological Risk asse ss ment (USDA, 2004) indicate that risk

of direct toxici ty to aquatic and terrestrial animals is unlikely, due to exposure via contaminated diet, dermal contact, and inhalation. Risks were evident to terrestrial and aquatic plants, with hazard quotients (equivalent to Agency RQ values) up to 4 for aquatic plan ts (peak concentrations) and up to 15,000 for terrestrial plants based on the NO AE C for vegetative vigor. The US Forest Service assessment considered only g r ound applications, which would likely result in lower RQs compared to aerial applications that are modeled in the OPP ecological risk

assessment.

Results from the BLM ecological risk assessment (BLM, 2005) are similar to those of the US Forest Service. No risks from direct sp r ay, drift, or surface runoff of sulfometuron methyl were

identified for ter restrial animals, fish or aquatic invertebrates. Risks to terrestrial and aquatic plants from off site drift and surface runoff were evident, with RQs up to 2,500 associated with aerial application 100ft from the treated area and up to 40 for aquatic plan ts from surface runoff to

### 25 a model pond. Results from modeling wind

- driven erosion did not indicate risk to terrestrial plants, although results depended largely on the treatment area size and may underestimate risks from larger scale applications.

2.6.2. Preli minary Identification of Data Gaps and Analysis Plan

Data from registrant

- submitted studies and the open literature were used to assess the potential effects of sulfometuron methyl a nd its major metabolites on non

- target organisms. For aquatic and terrestrial plants, a re

- review of the toxicity data indicated that the ecological effect studies meet basic guideline requirements and no data gaps were identified for terrestrial and fres hwater aquatic plants. For aquatic animals, a re

- review of the toxicity data indicates that no acceptable data were available for chronic toxicity to fish (freshwater, or marine/estuarine). For birds, no data were available to assess effects on avian grow th or reproduction. Similarly for mammals, no acceptable data were available on reproductive effects of sulfometuron methyl. Thus, for ecological effects, the following data gaps are identified along with associated uncertainties:

**•** Avian Reproduction Stud y (71

- 4 )

**•** Fish Early Life Stage Study for Freshwater or Estuarine/Marine Species (72

- 4 )

**•** 2

- generation reproduction study with rat (83

- 4)

There are no outstanding envi ronmental fate data gaps.

In accordance with OPP practices for conducting baseline ecologi cal risk assessments of pesticides (see the “Overview Document; US EPA, 2004), the primary method used to assess risk in this screening

- level assessment is the risk quotient (RQ). The RQ is the result of comparing measures of exposure to measures of effec t. A commonly used measure of exposure is the estimated exposure concentration (EEC) and commonly used measures of effect include toxicity

values such as the LD 50 

### or NOAEC. The resulting RQ is then compared to a specified LOC. If the RQ exceeds an LOC, then risks are identified.

2.6.3. Measures of Effect and Exposure

Considering the previous discussion of data gaps and risk assessment procedures, the following measures of effects and exposure presented in Table 4 are se lected for thi s baseline risk

assessment.

### 26 Table 4

. Measures of Ecological Effects and Exposure for S ulfometuron M ethyl

Assessment Endpoint Surrogate Species and Measures of Ecological Effect 1 Measures of Exposure

Birds 2 Survi val Bobwhite acute oral LD 50 Bobwhite and mallard subacute dietary LC 50

Maximum residues on food items (foliar) Reproduction and growth Bobwhite and mallard chronic reproduction NOAEC and

LOAEC (no studies available)

Mammals Survival Laboratory rat acute oral LD 50

Reproduction and growth Laboratory rat oral reproduction

chronic NOAEC and LOAEC (no acceptable studies av ailable)

Freshwater fish 3 Survival Rainbow trout and bluegill sunfish

acute LC 50 Peak EEC 4

Reproduction and growth Fathead minnow chronic (early life

- stage)

NOAEC and LOAEC (no acceptable studies av ailable) 60

- day average EEC 4

Freshwater

invertebrates Survival Water flea acute EC 50 Peak EEC 4

Reproduction and growth Water flea chronic (life cycle)

LOAEC 21

- day average EEC 4

Estuarine/marine
fish Survival Sheepshead minnow acute LC 50 Peak EEC 4

Reproduction and growth Sheepshead minnow chronic (early

life

- stage) NOAEC and LOAEC (No studies available) 60

- day average EEC 4

Estuarine/marine
invertebrates S urvival Eastern oyster acute EC 50 and mysid

acute LC 50 Peak EEC 4

Reproduction and growth Mysid chronic NOAEC and LOAEC (no data available) 21

- day average EEC 4

Terrestrial plants 5 Survival and growth Monocot and dicot seedling emergence and vegetative vi gor EC 25, EC 05 , and NOAEC values Estimates of runoff and spray

drift to non

- target areas

Insects Survival (not quantitatively assessed) Honeybee acute contact LD 50 Maximum application rate

Aquatic plants and algae Survival and growth Algal and vascular plant (i.e., duckweed) EC 50 and NOAEC values for growth rate and

biomass measurements P eak EEC

### 27 1 S pecies listed in this table represent most commonly encountered species from registrant

- submitted studies, risk assessment guidance indicates most sensiti ve species tested within taxonomic group are to be used for baseline risk

assessments.

2 Birds may be used as surrogates for amphibians (terrestrial phase) and reptiles.

3 Freshwater fish may be used as surrogates for amphibians (aquatic phase).

4 One in 1 0

- year return frequency.

5 Data required for 4 species of monocots from 2 families (must include corn) and 6 species of dicots from 4 families (must
include soybean). LD 50 = Lethal dose to 50% of the test population; NOAEC = No observed adverse effect

con centration; LOAEC = Lowest observed adverse effect concentration; LC 50 = Lethal concentration to 50% of the test population; EC 50 /EC 25 = Effect concentration to 50%/25% of the test population.



## 3. ANALYSIS

3.1. USE CHARACTERIZATION

Information in this section is taken from the “ Sulfometuron Methyl Use Closure Memo ” from John Pates, Special Review and Reregistration Division (dated January 30, 2007). In addition, some data submitted to the Agency by DuPont Corp. i s used by permission.

Sulfometuron methyl is a broad

- spectrum sulfonylurea herbicide (numerous other herbicides in this class are also registered for various uses in the United States). There are no agricultural uses for sulfometuron methyl, but it is used on a wide variety of non

- crop situations for vegetation

manag e ment ( railroad, highway, power line , and other rights

- of

- way ; suppression of vegetation

at utility substations, unimproved turf in industrial areas, in preparation of ground for asphalt or concrete paving , etc .) and in forestry plantings. It is applied either post

- emergent or pre

emergent. It works by blocking the active growing regions of stem and root tips. Sulfometuron methyl is formulated as a water dispersible granule (WDG) and applied using a variety of methods including helicopter, fixed

- wing aircraft, ground spray (boom and backpack) and spot

treatment ( Table 5 and Table 6 )

.

Sulfometuron methyl is generally applied once per year for non

- crop areas. In some instances (weed escap es) a second application may be made, but all products limit the total quantity of sulfometuron methyl that may be applied (from any source) to 6 ounces 1



### Table 9 of active ingredient

per year

. Therefore, application rates in general forestry, and for site prepara tion and/or release in conifer, hardwood and Christmas tree plantations, will vary significantly depending upon the specific purpose of the application and the desirable tree species. In forestry, uses can be similar to plantation sites, but may also incl ude the maintenance of access routes and fire breaks. It is further noted that use rates can also vary with climate and soil type. Ranges of application rates by use are summarized in

.

Considering all types of uses, reg ions of the U.S. where sulfometuron methyl appears to have the greatest use include the southeast and west coast states . Data from DuPont (used by permission)

indicate that OR and TX are the highest use states overall ( Table 7 ). However, Vegetation

1 

### That is, 0.375 pounds of active ingredient per acre per year.

### 28 Management LLC also markets sulfometuron methyl products and the geographical distribution of the use of its products could be somewhat different. The total amount used annually is estimated to be close to 250,000 pounds active ingredi ent Table 8

.

Table 5

. Permitted application methods for sulfometuron methyl, DuPont

Products

Forestry/

Plantations Aerial (fixed wing, helicopter), ground (closed cab), and backpack (spot spray). Veget ative Management Aerial (helicopter) and ground (closed and open cab).

Railroad Aerial (helicopter) and ground (closed and open cab).

Table 6

. Permitted application methods for sulfometuron methyl, Vegetation Management LLC Prod ucts

SFM Ground (broadcast, directed), air (helicopter

- only), backpack sprayers (forestry applications include banded or spot hand applications).

SFM Extra Ground (broadcast, directed), air (helicopter or fixed wing aircraft, backpack sprayers (forestr y applications include banded or spot hand applications).

Table 7

. States with high sulfometuron usage (based upon DuPont sales data,

2001

- 2004).

Thousands of Pounds A.I. Applied Annually Statewide

Use Site 1 to 5 5 to 10 1 0 to 20 > 20
Forestry OR, TX, LA, GA, VA AR, MS, AL

--- ---

Vegetation Management WA, OK, LA, MS, AL, GA, SC, VA, PA CA, TX OR

---

Railroad WA, OR, CA,
NM, ND, NE, KS, TX, IL, MS, OH, FL, MA TN, WV

--- ---

Total Uses (sales) MT, CO, NM, ND, NE, KS, OK, MN, IL, OH, PA, VA, SC, FL, MA OR, CA, AR, LA, TN, MS, AL, GA, WV TX OR

### 29 Table 8 . Annual usage of sulfometuron methyl in the US by use site.

**Use Site Low** 

**Estim. High** 

**Estim.** Annual Usage,
Lbs ai

(Commercial Christmas Trees

- Nurseries) 50 830

Forestry 89,000 100,000

Non

- crop Vegetative Management (VM

- includes Roadway, Utility & Pipeline) 80,000 100,000

Railroad (RR) 50,000 71,000

Total 230,000 261,000

Estimates reflect ranges from combined registrant and OP P

- BEAD generated estimates. Registrant estimates are combined for DuPont and Vegetation Management for any and all years of reported data. BEAD estimates reflect multiple data sources from 1999 to 2003 period.

### 30 Table 9 . Sulfome turon application rate ranges by product label and use site.

Product Name Type of

Formulation Additional

Active Ingredient(s) Use Site(s) Single App. Low Rate (pounds a.i. ) Single App. High Rate (pounds a.i

. )

DuPontTM Oust®

Herbicide

Or “Sulfometuron me thyl

75” Dispersible granules None (may be tank mixed) Forestry

Non

- Crop 0.047

0.047 0.375

0.375

DuPontTM Oust® XP

Herbicide Dispersible granules None (may be tank mixed) Forestry

Non

- Crop 0.023

0.047 0.375

0.375

DuPontTM

Oust® Extra Herbicide Dispersib le granules Metsulfuron Methyl Conifer

Plantations

Non

- Crop 0.023

0.016 0.281

0.188

DuPontTM Oustar®

Herbicide Dispersible granules Hexazinone Forestry 0.075 0.175

DuPontTM Westar®

Herbicide Dispersible granules Hexazinone Christmas

Trees Forestry

N on

- Crop 0.025

0.100

0.131 0.100

0.131

0.194

DuPontTM Landmark®

MP Herbicide Dispersible granules Chlorsulfuron Non

- Crop 0.023 0.281

DuPontTM Landmark® II

MP Herbicide Dispersible granules Chlorsulfuron Non

- Crop 0.035 0.350

DuPontTM Landmark®

XP Herbicide Dispersible granules Chlorsulfuron Non

- Crop 0.023 0.281

DuPontTM Landmark® II

XP Herbicide Dispersible granules Chlorsulfuron Non

- Crop 0.035 0.350

DuPontTM

ThrottleTM MP Herbicide Dispersible granules Sulfentrazone

Chlorsulfuron Non

- Crop ** 0.141 0.141

DuPontTM

ThrottleTM XP

Herbicide Dispersible granules Sulfentrazone

Chlorsulfuron Non

- Crop 0.141 0.141

### 31 Product Name Type of

Formulation Additional

Active Ingredient(s) Use Site(s) Single App. Low Rate (pounds a.i. ) Single App. High Rate (pounds a.i

. )



### SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Conifer Site Preparation (pre

- plant) 0.063 0.250

SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Conifer

Release (post

transplant) 0.125 0.188

SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Conifer Site Preparation

or Post

transplant for specific

weeds (e.g., Kudzu) 0.281 0.375

SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Hardwoods (seedlings

or transplants

in dormancy) 0.023 0.234

SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Non

- Crop:

“ Non

Agricultural

”* 0.035 0.375

### 32 Product Name Type of

Formulation Additional

Active Ingredient(s) Use Site(s) Single App. Low Rate (pounds a.i. ) Single App. High Rate (pounds a.i

. )



### SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Non

- Crop:

Under

a sphalt and

concrete
pavements (before paving) 0.188 0.375

SFM 75, SFM Extra Dispersible granules Only in tank mixes 

### Non

- crop: Turf (unimprove d) 0.023 0.188

** Non

- Crop lumps together uses such as rights

- of

- way, industrial site weed management, applicati ons prior to concrete or asphalt paving, unimproved turf, etc.

* “Non

- agricultural” is a term on Vegetation Management LLC labels that includes most of the non

- crop uses not otherwise specifically listed.

### 33 

## 3.2. E XPOSURE CHARACTERIZATION

3.2.1. Environmental Fate and Transport Characterization

The body of environmental fate data submitted demonstrates sulfometuron is mobile and persistent in the environment ( Table 10 ). Sulfometuron methyl is more soluble in neutral and

alkaline water than in acidic water

. The major route of dissipation for sulfometuron methyl is

believed to be aerobic and anaerobic degradation / metabolism in soil and water (pseudo first

order degradation half

- lives 2 

### generally around 2 to 6 months), with hydrolysis potenti ally

dominant under acidic conditions. F irst

- order rate aerobic soil metabolism half lives range from 52 to 58 days in two laboratory studies (technically both with the same soil type, but measured in two independent studies several years apart )

. In compa rison, lump dissipation half

- lives in the field ranged from 44 to 128 days at four sites (when considering only the residues remaining in the upper 15 cm of topsoil and calculating a lumped pseudo first

- order rate including all residue data during the enti re ca. 350 to 500 days of each study ) 3



### Sorption was not found to be strongly dependent on any of the major properties of the tested

soils in the registrant

- submitted studies

. The pKa of sulfometuron methyl is 5.4, and theoretically, adsorption may increase in very acidic s oils where the methyl ester form of . At all four field study sites, about 99 % of the applied sulfometuron methyl had dissipated from the upper six inches of the soil profile within 3 to 6 months after application, but dissipation of the small amount o f sulfometuron methyl remaining in the topsoil a few months after application was much slower. Sulfometuron methyl is subject to hydrolysis at environmental pHs; with significantly more rapid hydrolysis occurring under acidic conditions (e.g., a hydrolysis half

- life of 9 days at pH 5 and 139 days at pH 7). None of the laboratory and field studies in soil or sediment / water environments, albeit all at measured pHs somewhat greater than 5, show as rapid degradation as measured in the pH 5 hydrolysis study.

. Metabolism in the aquatic environment is variable , ranging from half

- life of 1 7 to 104 days in

anaerobic conditions and 9 to 187 days for aerobic conditions (the more rapid degradation with a

9

- day total system half

- life took place in a test system wit h sediment pH of 5.4 and water pH of 7.6)

. Although sulfometuron methyl persistence is expected to generally increase with higher soil pH (rotational crop restrictions for many other sulfonylureas, which are all weak acids, reflect this), a consistent tre nd was not found in the available studies.

Soil retention of sulfometuron methyl is low

, with Freundlich adsorption K F values ranging between

0.15 and 2.1 (mg/kg)/(mg/L) n in four test soils with soil organic carbon content ranging between 0.6 and 2.6 pe rcent.

2 All first

- order rates / degradation half

- lives discussed in this document, were, unless otherwised specified, calculated from linear regression of log

- transformed decay data.

3 In most cases simple first

- order degradation rates and half

- lives (calcula ted from linear regression of log

transformed data) are used (often along with DT50 and DT90 values) to represent sulfometuron methyl persistence

in the environmental fate studies. However, particularly in the field dissipation studies, over time pseudo f irst

- order kinetics often became less of an adequate descriptor for residue decline; in such cases the DT50 and DT90 values provide perspective on how much the decline patterns deviated from that predicted by a first

- order model.

### 34 sulfometuron would predominate. However, the pH range of the four test soils in the batch equilibrium adsorption / desorption study was only 6.7 to 7.7

. The published literature do seem to show more of a relationship of sulfometuron methyl and other sulfonylureas to mobility in soil; Weber et al. (2004) have reviewed the literature and concluded that there is consistent relationship between pH and mobility of sulfonylureas (“ NHSO 2 

### acid herbicides” means sulfonylurea herbicides) :

OM and pH were also the primary soil properties in best

- fit K d 

### equations obtained for

five of the six NHSO 2 

### acid herbicides, with all three soil properties utilized in the K d 

### equation for sulfometuron

- methyl. Cl was also one component of the K d 

### equation for

s ulfometuron

- methyl, but Cl and pH were also related soil properties. As was the case for the COOH acid herbicides, sorption increased as OM increased or as pH decreased.

Other abbreviations used in the above excerpt from the Weber et al. article:

OM = Soil organic mater content

Cl = Chloride ion concentration

COOH acid herbicides = Herbicides with a carboxy acid functional group such as 2,4

- D and Imazethapyr

Weber et al. developed the following specific equation for predicting sulfometuron adsorption

from soil properties:

K d 

### = 3.0 + 0.49(O M)

– 0.03(Cl)

– 0.47(pH) ± 2.3

In general, sulfonylureas were found to have the strongest correlation between soil pH and the measured pesticide K d 

### of any of ten families of pesticides tested; the correlation of soil per cent
OM and K d 

### was second to “OH acid” (uracil) herbicides such as bromacil. Similarly, soil pH and % OM together accounted for more of the variability in soil K d 

### for these two classes of herbicides (54% for sulfony l ureas and 67% for uracils) than for any of the other pesticide

families evaluated.

Based on the of McCall et al. (1981) mobility classification system sulfometuron methyl is

mobile to highly mobile in each of the test soils

.

In terrest rial field dissipation studies at four US sites , leaching o f parent sulfometuron methyl

occur r ed at measurable concentrations ; ( >10 ppb in depth increments from 15 to 90 cm ) was

noted at each test site. Consistent with the terrestrial field dissipation and the aged leaching results, minimal level s (but possibly still high enough to be phytotoxic) of sulfometuron methyl

residues wer e estimated for ground water (0.33 ug/L for vulnerable aquifers ) using the SCI

GROW model. Leaching of the degradates was not evaluated in the field dissipation studies.

Sulfometuron persistence in water indicates that if, either via spray drift or any runoff event, sulfometuron methyl reaches surface water, it may persist for a few weeks to several months and present some concern to surface water resources. The fairly low use rate ( maximum annual rate of 0.375 lb ai/A) and the apparent typical use pattern of applying in only one or two years out of

### 35 a several year period should limit the actual exposure of sulfometuron methyl parent residues in

surface water (however, note that sulfom eturon methyl could negatively affect certain sensitive plants at very low exposure levels because it is such a potent herbicide with respect to many plant species )

.

Aquatic modeling at the highest application rate applied every year results in a peak s urface water estimated environmental concentration (EEC) of 31

. 5 μ g/L; additional assumptions for this modeling are discussed in “Section 3.2.2.2

, A quatic Exposure Modeli ng ”. Note that sulfometuron methyl was not predicted to accumulate in the receiving pond so the effect of sulfometuron methyl on EECs determined only was significant for the chronic (not acute) exposure estimates.

Volatility studies were not reported. H owever, based its chemical properties, volatilization is not expected to be a route of dissipation of sulfometuron methyl in water or soils.

Sulfometuron methyl degrades to CO 2 

### under aerobic, non

- sterile conditions (relatively little

mineralization occ urs under sterile conditions), but with significant accumulation of intermediate degradates, including a sulfonamide and saccharin from the phenyl ring part of the parent molecule and a pyrimidine amine from the pyrimidine ring portion (see “ A PPENDIX A : Structures and Chemical Names of Sulfometuron methyl Metabolites ”). For the phenyl ring labeled studies, CO 2 

### was up to 28 to 44 % of applied at study termination whereas for the pyrimdine

- ring labeled studies CO 2 

### was up to 53% of applied at study termination (see Table 10

, aerobic soil metabolism studies, for further information). Additional details on the accumulation of sulfometuron methyl degradates in the various studies will be provided in a Drinking Water Assessment for Sulfometuron Methyl.

The only submitted studies directly evaluating the fate of sulfometuron methyl degradates were adsorption / desorption studies on the pyrimidine amine and saccharin. The soil retention

characteristic s of two of the sulfometuron methyl degradates were studie d in batch equilibrium adsorption / desorption studies: saccharin K f 

### s were 0.03 to 0.27 and the pyrimidine amine K f 

### s were 0.17 to 3.70 in the four test soils ( Table 10 ). Th is means saccharin would be slightly more mobile and the pyrimidine amine slightly less mobile than parent (K f 

### s of 0.15 to 2.12 in the same

four soils )

Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Hydrolysis [161

- 1] t 1⁄2 = 8.8 days @ 25 o C, pH 5;

t 1⁄2 =139 days @ 25 o C, pH 7;

t 1⁄2 = 224 days @ 25 o C, pH 9.

Major degradates (from cleavage of the sulfonylurea bridge):

Sulfonamide

– only in acidic water

Saccharin

– all pH levels Pyrimidine amine

– all pH levels 42715201

### 36 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Direct photolysis in

water [161

- 2] Combined labels results:

t 1⁄2 = 428 days @ 24 o C, pH 5;

t 1⁄2 = stable @ 24 o C, pH 7;

t 1⁄2 = stable @ 24 o C, pH 9. (calculated by the difference in degradation rates between ir radiated and dark controls and adjusting for typical light levels on sunny days)

Major degradates (irradiated water): pH 5: sulfonamide, pyrimidine amine; pH 7: none; pH 9: none. 42182401

43174101

Photolysis on

soil [161

- 3] t 1⁄2 = 72.1 days @ 25 o C,

S tudy duration was 33 days, substantial degradation occurred in dark controls and the calculated photolysis half

- life represents the difference in the dissipation rate in the irradiated and the dark control samples.

Major degradates (from cleavage of the s ulfonylurea bridge): Saccharin reached a maximum of 48.4% of the applied at 33 days (study termination.) Pyrimidine amine reached a maximum of 53.1% at 33 days (study termination.) There was no substantial difference in the degradation pathway of

sulfometu ron methyl between the irradiated

- and the dark control soil.

No other degradate accounted for >4% of the applied radioactivity regardless of whether the phenyl ring or the pyrimidine ring was 14 C

labeled. 41420601

### 37 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Aerobic soil

metabolism [162

- 1] Study with [pyrimidine

- 2

- 14 C] Sulfometuron Methyl Soil: Keyport Silt loam (pH 6.3 , 1.6% O.C. ) from Delaware

First Order t 1⁄2 : 57.8 days (r 2 = 0.9239).

Observed DT50: 23 days.

Observed DT90: 110 days.

Sterile soil First Order t 1⁄2 : 

### 364 days

Major transformatio n products: Pyrimidine amine (maximum 41.0% of the applied) Pyrimidine

- ol (maximum 10.5% of the applied).

CO 2 (maximum 53.1% of applied). Minor transformation products: Free acid sulfometuron methyl. Pyrimidine urea. 42091401

Aerobic soil

metabolism [162

- 1] Study with U

- 14 C

- phenyl

- label

43174102
and

245375 ed Sulfometuron Methyl

Soil: Keyport Silt loam (pH 6. 4, 1.6 % O.C. ) from Delaware (0.12 mg a.i./kg).

First Order t 1⁄2 : 52.5 days (r 2 = 0.9239).

Observed DT50: 29 days.

Observed DT90: 162 days.

Major transformation pr oducts:

Sulfonamide.

Saccharin. Free acid sulfonamide plus urea (1.0 mg a.i./Kg only).

CO 2

. Minor transformation products: Free acid sulfonamide plus urea (0.12 mg a.i./Kg only)

### 38 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Anaerobic aquatic

metabolism [162

- 3] Study performed with [pyrimidine

- 2

- 14 C] Sulfometuron Methyl

Matrix: Bradenton Pond water

- sand sediment.

First Order t 1⁄2 : 37.4 days (r 2 = 0.6125). Observed total system DT50: 22 to 61 days (inconsistent decline data). Observed total system DT90: 102 days.

Matrix: Landen berg Pond water

- sandy loam sediment.

First Order t 1⁄2 ; total system: 17.1 days (r 2 = 0. 0.6394). Observed total system DT50: 6.1 days. Observed total system DT90: 21.7 days.

Major transformation products (both systems): free acid sulfometuron methyl. pyrimi dine amine. Minor identified transformation products: pyrimidine

- ol.

CO 2

. 42091402
and

43188601

### 39 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Anaerobic aquatic

metabolism [162

- 3] Study with [phenyl

- U

14 C] Sulfometuron Methyl

Matrix: Pond water

- sandy loam sediment from Bradenton,

Florida. (water pH 5.5 . Sediment: pH 5.1; O.C. = 5.9 %).

First Order t 1⁄2 ; total system: 104 days (r 2 = 0.4883) *

. Observed DT50 in total system: ca. 21 days.

Sterile t 1⁄2 ; total system: 44 days * Based upon limited and inconsistent data.

Matrix: Pond water

- silt loam sediment from Landenberg, Pennsylvania. (water pH 5.8 . Sediment: pH 5.6; O.C. = 2.1 %).

First Order t 1⁄2 ; total system: 87 days (r 2 = 0.3577). Observed DT50 in total system: ca. 28 days.

Sterile t 1⁄2 ; total system: 175 days

Matrix: Pond water

- loam sediment from Sask atoon, Canada. (water pH 8.3 . Sediment: pH 7.8; O.C. = 0.9 %).

First Order t 1⁄2 ; total system: 77 days (r 2 = 0.5853). Observed DT50 in total system: ca. 70 days.

Sterile t 1⁄2 ; total system: 399 days

Matrix: Pond water

- silt loam sediment from Walnut Grove, Tennessee. (water pH 5.5 . Sediment: pH 5.1; O.C. = 0.5 %).

First Order t 1⁄2 ; total system: 73 days (r 2 = 0.5691). Observed DT50 in total system: ca. 28 days.

Sterile t 1⁄2 ; total system: 95 days

Major transformation products:

saccharin.

free acid sulfona mide. Minor identified transformation products: Methyl

- 2

- aminocarbonyl(aminosulfonyl)benzoate. 4413010

- 20 (143540)

### 40 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Aerobic aquatic

metabolism [162

- 4] Study performed with [pyrimidine

- 2

- 14 C] Sulfometuron Methyl

Matrix used: Pond water

- silt loam sedimen t (Landenberg, acidic system).

First Order t 1⁄2 ; total system: 9.2 days (r 2 = 0.94). Observed DT50 in total system: 15 days.

Observed DT 9 0 in total system: 31 days (extrapolated).

Major transformation products: Pyrimidine amine (pyrimidine label). Hydroxyme thyl

- pyrimidine sulfometuron methyl. Free acid sulfonamide (phenyl label). Sulfonamide (phenyl label). Minor identified transformation products:

CO 2

.

Matrix used: Pond water

- sand sediment (Bradenton, alkaline system).

First Order t 1⁄2 ; total system: 187.3 d ays (r 2 = 0.5713). Observed DT50 in total system: >39 days.

Major transformation products: Pyrimidine amine (pyrimidine label). Free acid sulfonamide (phenyl label). Minor identified transformation products: Hydroxymethyl

- pyrimidine sulfometuron methyl.

S ulfonamide (phenyl label).

CO 2

. 42091403
and

43174103

### 41 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Adsorption/ Desorption (K d and

K

oc in L Kg

- 1 ) Parent sulfometuron methyl : Soil type: Chino Sandy loam ; pH 7.1, organic carbon 1.0%

. Adsorption K d : 0.35. Adsorption K

oc : 35. Freundlich adsorpti on K F : 0.153. Freundlich adsorption K Foc : 14.7.

1/N 0.504

Soil type: Fargo silt loam ; pH 7.7, organic carbon 2.6%

. Adsorption K d : 2.07. Adsorption K

oc : 79.6. Freundlich adsorption K F : 2.12. Freundlich adsorption K Foc : 83.2.

1/N 1.23

Soil typ e: Miaka Sand ; pH 7.0, organic carbon 0.6%. Adsorption K d : Not applicable. Adsorption K

oc : Not applicable. Freundlich adsorption K F : 0.508. Freundlich adsorption K Foc : 87.6.

1/N 1.61

Soil type: Tama Silt loam ; pH 6.7, organic carbon 1.5%

. Ad sorption K d : 0.79. Adsorption K

oc : 52.7. Freundlich adsorption K F : 0.974. Freundlich adsorption K Foc : 67.2.

1/N 0.851 42789301

### 42 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Adsorption/ Desorption Of Degradates Pyrimidine amine

Although the registrant conducted adsorp tion / desorption studies for the pyrimidine amine degradate, the results were insufficiently documented to verify their calculations of adsorption coefficients (and furthermore, they only reported Freundlich adsorption “K F ” and

“K Foc ” values without 1/N v alues (or sufficient data for the reviewer to calculate them) and K d values were also not reported.

For rimsulfuron, a structurally similar pyrimidine amine degradate (but with 4

- , 6

- di methoxy rather than 4

- , 6

- dim ethyl substitution of the pyrmidine amine ) was reported to have K d values of 0.23 to 1.52 and

K

oc values of 19 to 61 in four test soils. See DP Barcode D326660

, EFED review of rimsulfuron methyl new uses dated 3/14/07 for more

details

.

Saccharin

Although the registrant con ducted adsorption / desorption studies for saccharin, the results were insufficiently documented to verify their calculations of adsorption coefficients (and furthermore, they only reported Freundlich adsorption “K F ” and “K Foc ” values without 1/N

values an d K d values were also not reported.

Saccharin has been reported elsewhere to be quite mobile, e.g.: When tested as a degradate of metsulfuron methyl ( http://e c.europa.eu/food/plant/protection/evaluation/existactive/list1

- 13_en.pdf ) 42789301

### 43 Table 10

. Key results of sulfometuron methyl environmental fates studies.

Pa rameter [Guideline #] Value 1 

### MRID(s)

Terrestrial Field/Lysimeter Dissipation 2 Greenville, MS silty clay loam soil : pH 6.7, 0.6% O.C.

Half

- life: 49.2 days (based on 0

- to 359

- day data); 12.2 days (based o n 0

- to 91

- day data).

DT90: 32 days Major transformation products detected (>0.01 ppm):

Sulfometuron free acid (SFA) Pyrimdine amine (PYA)

Sulfonamide IN

- D5803 (SFN)

Saccharin IN

- 581 (SCC)

Rochelle, IL silty clay loam soil : pH 6.8, 1.0 % O.C.

Half

- life: 1 28 days (based on 0

- to 723

- day data, residues in 0

- 15 cm depth only); 14.4 days (based on 0

- to 90

- day data).

DT90: 35 days Major transformation products detected (>0.01 ppm): PYA, SFN, and SCC

Uvale, TX clay soil : pH 7.9, 1.3% O.C.

Half

- life: 53.3 da ys (based on 0

- to 447

- day data); 13.0 days (based on 0

- to 90

- day data).

DT90: 25 days Major transformation products detected (>0.01 ppm): PYA, SFN, and SCC

Maldera, CA sandy loam soil : pH 7.8, 0.7% O.C.

Half

- life: 44.1 days (based on 0

- to 420

- day da ta); 22.9 days (based on 0

- to 180

- day data).

DT90: 55 days Major transformation products detected (>0.01 ppm): PYA, SFN, and SCC Numbers

43212101
and

43637101

1 Unless otherwise specified, half

- lives were derived with a “Log

- linear” degradation rate cal culation; a process of calculating degradation rates and half

- lives from linear regression of log

- transformed concentration measurements over time. This provides a first

- order type of measurement of pesticide decline.

2 For these field dissipation studies , differences between half

- lives measured over various time durations apparently reflect both slowing of degradation at lower temperatures and a large variability in measured concentrations; also, a 2

- compartment degradation model for adsorbed and dissolve d sulfometuron is quite possibility more appropriate (little dissipation of the remaining residues in the topsoil occurred during the second year of these studies, for example). A 2

- compartment model was not used to represent dissipation rate here

because the data are not sufficient robust (e.g., very high variability between replicate measurements), the effects of weather changes on degradation rate cannot easily be isolated, and the amount of residues lost through dissipation out of the topsoil also canno t be separated from the amount lost to degradation. At all four of these field study sites about 99% of the applied sulfometuron methyl dissipated from the topsoil within 3 to 6 months.

### 44 3.2.2. Measures of Aquatic Exposure

3.2.2.1. Aquatic Exposure Monitoring and Fi eld Data

A few surface

- water monitoring studies are available for sulfometuron methyl. In streams, most recently Michael (2003) found, after application of sulfometuron methyl at 0.42 kg/ha to watersheds of unspecified area (reflecting a forestry planting usage) that concentrations of sulfometuron methyl in runoff water collected at the edge of the field reached a maximum of 49 ug/L (24

- hour average ) . However, samples taken approximately 150 meters downstream never exceeded the minimum detection limit of 1 ug/L (a fairly high MDL given the potency of this herbicide) reported in this study ( stream flow data were not supplied )

.

In the most widespread monitoring survey available, sulfometuron methyl was detected only rarely (2 of 132 samples from 52 sites

– mostly Midwestern US streams and rivers, but including some reservoirs as well); see Battaglin et al. ( 2000 ). The maximum concentration of sulfometuron methyl detected was 0.018 ug/L; but it is not known how much sulfometuron methyl usage was associated with the watersheds included in this monitoring survey.

Blomquist et al. (2001) in a monitoring study of 12 reservoir systems across the United States

found sulfometuron occurred abo ve the minimum reporting limit of 0.05 ug/L in 12% of the samples coll ected with a maximum concentration of 0.16 ug/L and a 95 th 

### percentile concentration of 0.10 ug/L. This study focused on drinking water supplies and may not represent

the most vulnerable water bodies for ecological exposure.

3.2.2.2. A quatic Exposure Modeling

EFE D’s PRZM ( P esticide R oot Z one M odel) and EXAMS ( EX posure A nalysis M odeling

S ystem) model s ( Table 11 ) w ere used in this assessment to estimate the exposure of sulfometuron methyl residues to the aquatic environment as a result of t he proposed use s in forestry and various non

- crop land vegetation control uses. P RZM simulates pesticide transport

as a result of runoff and erosion from an 10

- hectare agricultural field and EXAMS considers environmental fate and transport of pesticides i n surface water and predicts EECs in a standard pond (10,000

- m 2 

### pond, 2

- m deep), with the assumption that the small field is cropped at 100%. Calculations are carried out with the linkage program shell

– PE 5 .pl

- which incorporates the

standard scenarios developed by EFED. (For additional information see http://www.epa.gov/oppefed1/models/water/index.htm )

. Potential exposure from ground

- water (for, example, via contaminated irrigation wa ter) was also estimated using the SCI

- GROW

model.

### 45 Table 11

. Models Used to Estimate Exposure Concentrations for Aquatic Ecosystem.

Exposure Estimate Type Models Used
Aquatic ecosystems Surface water (Tier II) PE v5.0, PRZM v3.12.2, EXAMS v2.98.04.06

Details of executables:

PRZM 3.12 .2 , named przm3122.exe (dated May 12

, 2005 )

EXAMS 2.98.04 .06

, executable file na med EXAMS.EXE (dated April 12, 2005 )

PE v5.0

, Executable file PE5.pl ( dated July 24, 20 0 6) Ground water (Tier I) SCI

- GROW v2.3 Executable file sg23.exe (dated May 16, 2006)

The estimated environmental concentrations ( EECs ) were predicted assuming 1 aerial or ground application at t he maximum allowable single application rate of 0.375 lbs. a.i./A (which also

repre sents the maximum annual application amount permitted on all labels). Applications were broadcast without incorporation, according the uses endorsed by the label. None of the available modeling scenarios as currently set up represents a clear match for th e sulfometuron methyl use pattern as described in Section 3.1

. Nonetheless, a combination of scenarios which represent usage patterns and locations that can reasonably be expected to represent a range of conditions

for the for estry planting and non

- crop uses of sulfometuron methyl were able to be selected from

the suite of available standard scenarios and, with slight adjustments , the available regional

scenarios ( see Table 12 ). The major adjustments to the standard scenario modeling were:

1. Specific regional scenario adjustments

. The rights

- of

- way regional scenarios were selected for this national assessment because they are the only scenarios currently approved in EFED for specific modeling of t his type of use. However, they were run with both their native meteorological files as the source of weather data and with alternate weather data files believed to represent more runoff

- prone climates that may represent areas with significant use of

sulfo meturon methyl

2. Modeling with multiple application dates

. The multiple PRZM

– EXAMS runs with multiple application dates were used for final development of EECs for the highest exposure scenarios because the product labels frequently refer to uses t hat are recommended for spring, summer, fall, and even winter application (although only spring, summer, and fall dates were tested with our modeling, as they were judged to be significantly more common than winter applications).

The most important reas on for modeling with multiple application dates is that there is significant variability in the results (calculated EECs) of the modeling that can arise strictly as a factor of the application date chosen. In fact, when , for example, the Texas Right

- of

- Way scenario (using Port Arthur, Texas meteorological data) was rerun with 28 different application dates, the acute (peak daily value) EECs (a distribution of 1 in 10

- year return frequency values)

### 46 ranged from 8.5 to 49.5 ug/L and the 90

- day EECs ranged from 5.5 to 27.2 ug/L 4



### The pesticide

- specific input parameters for this modeling (summarized in . This is quite a significant difference when it is considered that this variability is solely for the 1 in 10 year return frequency exposure levels, not for all of the year

- to

- year differences in EECs from the modeling.

Sulfometuron met hyl product labels allow for flexibility in when sulfometuron methyl is applied and there is not as much consistency in the optimal application season as there would be, for example, with most agricultural crops. In this case, the 90 th 

### percentile applicat ion date model

results were chosen for risk calculations

.

Bot h aerial and ground applications were simulated, but ground applications were only simulated for a few scenarios since the ground application assumption yielded lower EEC estimates for

sulfometu ron methyl than aerial application s at the same site.

Table 13 ) were selected from the environmental fate studies submitted by the registrant, and in accord ance with

the US EPA

- OPP EFED water model parameter selection guidelines, Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides , Version II, February 28, 2002.

We considered modeling total residues of sul fometuron methyl (including sulfometuron methyl,

sulfometuron free acid , the sulfonamide, saccharin, and the pyrimidine amine) as well, since the Health Effects Division has made a preliminary call that they might contribute to toxicity in mammals (electro nic mail message from Larry Chitlik, HED dated /7/2007). However, with the available data total residue model inputs would be different from assumptions for the parent compound ( Table 13 ) in that stability to hydro lysis, aerobic aquatic metabolism, and anaerobic aquatic metabolism hand to be as sumed (only aerobic soil metabolism had a measurable total

residue half

- life: 136 days)

. This would lead to an assumption of no degradation in the pond represented by EXAMS, which is set up for a pond with no turnover in ecological risk assessments (an additional conservative assumption). Fur ther details on the limitations of the modeling and uncertainties regarding exposure to sulfometuron methyl degradates are provided

in Se ction 3.2.4.3

.

4 A measure of how often ( on average) an event will occur that is greater than some chosen value . In this case, the chosen frequency is 1 in 10 years; the chosen EEC is such that the sulfometuron methyl concentration would equal or exceed the EEC on average of one in ten years. The full distribution of the 1 in 10 year return frequency values is provided in APPENDIX C: Ecological Aquatic Exposure Modeling

.

### 47 TABLE 12 . AQUATIC EXPOSURE W ITH PRZM

– EXAMS: MODELING SCEN ARIOS
AND REPRESENTATIVE U SAGE PATTERN SUMMARY

.

Scenario ID 1 WBAN (met. file) 2 appl.

meth. CAM 3 applictn.

da tes (MM

- DD) Use(s) represented

PA Apples (std) W14751 Aerial 2 03

- 15 Forestry, Conifer Plantations

FL Citrus (std) W12844 Ground 1 03

- 01 Forestry, Conifer Plantations
FL Citrus (std) W12844 Aerial 1 03

- 01 Forestry, Conifer Plantations 

### FL Turf (std) W12 834 Ground 1 03

- 01 Non

- crop (e.g., unimproved turf & rights of way) 

### FL Turf (std) W12834 Aerial 2 03

- 01 Unimproved turf, non

- crop 

### PA Turf (std) W14751 Aerial 2 03

- 01 Unimproved turf, non

- crop



### OR Xmas Trees (std) W24232 Ground 1 03

- 01 Christmas Trees, Fo restry, Conifer

Plantations



### OR Xmas Trees (std) W24232 Aerial 2 03

- 01 Christmas Trees, Forestry, Conifer

Plantations

CA right of way (RLF) W23234 Aerial 2 03

- 01 Non

- Crop (rights of way, unimproved turf, railroads, etc.)
CA right of way (RLF) W94224 Aer ial 2 03

- 01 Non

- Crop (rights of way, unimproved turf, railroads, etc.)
CA right of way (RLF) W94224 Aerial 2 Feb to Oct 4 Non

- Crop (rights of way, unimproved turf, railroads, etc.)
TX right of way (BSS) W13958 Aerial 2 03

- 01 Non

- Crop (rights of way, unim proved turf, railroads, etc.)
TX right of way (BSS) W12917 Aerial 2 03

- 01 Non

- Crop (rights of way, unimproved turf, railroads, etc.)
TX right of way (BSS) W12917 Aerial 2 Feb to Oct 4 Non

- Crop (rights of way, unimproved turf, railroads, etc.)
TX right o f way (BSS) W12917 Ground 2 Feb to Oct 4 Non

- Crop (rights of way, unimproved turf, railroads, etc.)

1 Native scenario designation state and use site. Native scenario target in parenthesis, where: std = std scenario used
in nationwide assessments; RLF = s cenario originally developed for regional assessments related to the California

red

- legged frog; and BSS = scenario originally developed for regional assessments related to the Barton Springs

salamander.

2 The Weather Bureau Automated Network (WBAN) meteor ological station used for weather inputs in the runoff modeling.

3 CAM = Chemical application method. CAM 1 is application direct to soil, although a 4 cm incorporation depth is automatically assumed, to account for surface roughness. CAM 2 is linear folia r decay based on crop canopy, default soil incorporation depth for non

- foliar intercepted chemical is 4 cm.

4 Only one application per year in each model run. PRZM

- EXAMS was separately run for application dates between February 1 and October 29, increasin g the application date by 10 Julian days with each successive model run (2/1, 2/11, 2/21, etc.).



### Table 13

. PRZM/EXAMS input parameters for modeling (Aquatic ecological EECs).

Input Parameter Value* Reference

### 48 Table 13

. PRZM/EXAMS input parameters for modeling (Aquatic ecological EECs).

Input Parameter Value* Reference

Molecular Weight (gram mole - 1 ) 364.38

MRID: 416728

- 02 Vapor Pressure (torr) 5

. 4 x10
- 1 6

Aerobic Soil Metabolism Half

- life (days) 60.9 90% Upper Confidence Limit of the mean of measured

values (MRID s 42091401 ; 43174102 and 245375 )

Water column Half

- life (days) (Aerobic Aquatic Metabolism

half

- life) 292 90% Upper Confidence Limit of the mean of measured

values (MRID s 42091403 and 43174103 )

Benthic sediment Half

- life (days) (Anaerobic Aquatic Metabolism

half

- life) 76 90% Upper Confidence Limit of the mean of measured

v alues (MRID s 43174102, 245375, 42091402, and

43188601 )

Application Rate (Kg a.i./ha) 0.41 Efficiency= 0.99 for ground spray , 0.95 for aerial.

Application Number (Method of application) One Product Label; typical use.

Application method; Depth of

In corporation (cm) Aerial or ground;

0 CAM=1 or CAM=2 depending on the use.

Spray Drift (fraction) 0.01 (GS) , 0.05 (aerial) De fault values per guidance document . (GS= ground spray)

Solubility (ppm) 244 Highest solubility was recorded for alkaline water ( 12 ,500 ppm at pH 8.6) . However, experience from other studies indicates these experimental values are too high ( Therefore, this value was not multiplied by 10 as normally recommended).

K

oc (L Kg - 1 ) 47.5 Average of four values (MRID 42789301 ).

K

oc model wa s determined to be appropriate.

Hydrolysis Half

- life @ pH 7 (days) 139 days MRID 42715201

.

Direct Aqueous Photolysis Half

life(days) Stable Maximum dark control corrected value (MRID s 42182401 and 43174101 )

Fate data values are as per Guidance for Sel ecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides; Version II February 28, 2002.



### The highest exposures were determined to occur with aerial applications at rights of way sites; the southeast Texas (using Port Arthur, T exas weather) scenario and a scenario for Pacific Coastal areas utilizing Astoria, Oregon weather). The Florida citrus scenario also yielded relatively high EEC estimates, and it provides some representation of forestry planting and other

uses in the sout heastern US ( Table 14 ). Chosen EEC values for the aquatic risk assessments are provided in Table 15

. Note that whereas in the modeling sulfometuron methyl applications were

### 49 simulated for every year of a 30

- year simulation period for each scenario (standard EFED practices if the product labels do not expressly prohibit this), in most cases sulfometuron does not appear to be repeatedly used from year to year at a particular site. However, in this modeling, sulfometuron methyl was not predicted to accumulate in the receiving pond so the effect of

sulfometuron methyl on EECs determined only was significant (e.g., if the 30 applications simulated were to be spread over 150 years, the acute EECs would remain abo ut the same, but

the chronic EECs estimated would be lower)

.

### 50 Table 14 . Estimated environmental concentrations ( μ g/L) for aquatic exposure to parent sulfometuron methyl: scenario

- specific results from PRZM

- EXAMS modeling.

(all values are listed as ppb or ug/L)

**Scenario Description**  **Site** 1 **Peak 96 hr**  **21 Day**  **60 Day**  **90 Day**  **Yearly Lifetime**  **Applictn. Date,** 

**mm**
**- yy**  **App**

**- Type**  3

PA Apple Fr 2.28 2.23 2.05 1.61 1.39 0.45 0.31 3

- 15 aerial

FL Citrus Fr 9.39 9.09 7.97 6.03 4.93 1.48 0.72 3

- 01 aerial

FL Citrus Fr 7.32 7.08 6.19 4.71 3.81 1.14 0.43 3

- 01 ground

FL Turf NC 1.47 1.43 1.27 1.01 0.86 0.29 0.20 3

- 01 aerial

FL Turf NC 0.46 0.44 0.39 0.30 0.25 0.09 0.05 3

- 01 ground

PA Turf NC 1.22 1.20 1.12 0.96 0.84 0.29 0.26 3

- 01 aerial

OR Xmas F r 1.57 1.53 1.42 1.21 1.06 0.40 0.29 3

- 01 aerial

OR(Astoria) Xmas Fr 2.87 2.82 2.61 2.18 1.91 0.73 0.42 3

- 01 aerial

OR(Astoria) Xmas Fr 1.78 1.74 1.58 1.29 1.13 0.43 0.35 9

- 01 aerial

CA RightsWay NC 8.33 8.15 7.47 6.17 5.35 2.00 0.84 3

- 01 aerial

CA(As

- OR) 4 RightsWay NC 13.64 13.37 12.39 10.35 9.04 3.42 1.34 3

- 01 aerial
CA(As

- OR) RightsWay 90 th

date 5 NC 11.01 10.83 10.10 8.46 6.73 2.73 1.44 various 6 aerial

TX RightsWay NC 6.96 6.74 5.99 4.72 3.94 1.22 0.64 3

- 01 aerial

TX(PtAr) 7 RightsWay NC 11.87 1 1.55 10.66 8.84 7.41 2.30 1.06 3

- 01 aerial

TX(PtAr) RightsWay 50 th date NC 21.75 20.93 18.33 13.51 10.99 3.39 1.97 Various aerial

TX(PtAr) RightsWay 90 th date NC 31.45 30.34 26.24 20.45 16.49 5.26 3.14 Various aerial

TX(PtAr) RightsWay 90 th date NC 26.0 8 25.20 21.64 15.51 12.48 3.92 2.05 Various ground

1 Fr = forestry plantings uses. NC = Non

- crop uses on rights of way, industrial land with unimproved turf, on ground prior to paving, railroads, etc.

2 CAF = crop area factor.

3 App

- Type = application ty pe.
4 As

- OR = Astoria, Oregon meteorological weather substituted for the original San Francisco, CA weather data for this regional sce nario.

5 90 th Date or 50 th Date = For the specified exposure distribution the 90 th percentile of the 10 th percentile excee dence probability (1 in 10 year return

### 51 frequency) values were sorted for each model run with different Julian day application dates (single application per year). Then each of the 1 in 10 year values were sorted and the concentration exceeded for 1 in 10 of the possible application dates was selected to be representative for the

scenario.

6 Pt

- Ar = Port Arthur, Texas meteorological weather substituted for the original Austin, TX weather data for this regional scenari o.
7 Only one application per year in ea ch model run. PRZM

- EXAMS was separately run for application dates between February 1 and October 29, increasing the application date by 10 Julian days with each successive model run (2/1, 2/11, 2/21, etc.).

### 52 Table 15

. Sulfometur on methyl surface water EECs used in aquatic risk

assessment.



## Surface Water EECs in ug/L 1



### Application

method Peak 96

- hr 21

- day 60

- day 90

- day Annual Average Yearly Average

Aerial 31.45 30.34 26.24 20.45 16.49 5.26 3.14


### Ground 26.08 25.20 21.64 15.51 12 .48 3.92 2.05

1 Results based on PRZM/EXAMS modeling described in Section 3.2.2.2 using the maximum annual application

rate of 0.375 lb ai/A.



### Since some exposure to sensitive terrestrial plants is possible f rom contaminated ground water as well as from ground

- water entering surface waters during base flow periods, a Tier I estimate of ground

- water exposure was conducted using SCI

- GROW 2.3 (executable file dated 5/16/2006). The estimate of 0.33 ug/L concentra tions in vulnerable ground water ( defined as aquifers where the water table is about 10 to 30 feet in depth and the overlying soil layers are permeable) would indicate that contributions from ground water into surface waters would not reach levels

estimate d to enter surface waters from direct runoff and spray drift in the PRZM

– EXAMS modeling . However, the levels of sulfometuron methyl in contaminated well water used for irrigation could be phytotoxicologically significant.

Table 16 . Estimated concentrations of sulfometuron methyl in ground water (SCI

GROW inputs and results).

Input Parameter Value* Reference

Aerobic Soil Metabolism Half

- life (days) 55.2 Mean of measured values (MRID s 42091401 ; 43174102 and 245375 )

Applicatio n Rate (Kg a.i./ha) 0.41 Maximum permitted single (and annual) rate.

Application Number (Method of application) One Typical use.

K

oc (L Kg - 1 ) 73.4 Median of four values (MRID 42789301 ).

SCI

- GROW Modeling Results

Acute Exposure EEC, ug/L 0.33

C hronic Exposure EEC, ug/L 0.33

### 53 3.2.3. Measures of Terrestrial Exposure

3.2.3.1. Terrestrial Exposure Modeling

Terrestrial Animals. Estimates of terrestrial wildlife exposure to pesticides are typically evaluated for the dietary pathway for birds and mammals (US EPA, 2004). Birds are used as surrogates for reptiles and terrestrial phase amphibians when specific data are unavailable for these taxonomic groups. Consistent with this practice and with the conceptual model for

sulfometuron in Section 2.5

, a screening

- level risk assessment was conducted for spray applications of sulfometuron methyl for estimating wildlife exposure to sulfometuron methyl via dietary uptake. Specifically, pesticide residues on food items of wildlife (birds a nd mammals)

were estimated based on the assumption that animals are exposed to a single pesticide residue (sulfometuron methyl) in a given exposure scenario. For this terrestrial exposure assessment, only spray applicat ion methods for sulfometuron methyl are considered , since labeling does not permit granular applications.

E stimatin g sulfometuron methyl concentrations on wildlife food items focuses on quantifying possible dietary ingestion of residues on vegetative matter and insects. No field residue d ata or field study information is available for sulfometuron methyl except for lump dissipation rates from the application of sulfometuron methyl to two forest sites (MRID s 42091404 and

43174104 )

, therefore, the residue estimates were based on a nomogram t hat relates food item residues to pesticide application rate. The residue EECs were generated from a spreadsheet

based model (T

- REX Version 1. 3

. 1 ) that calculates the decay of a chemical applied to foliar surfaces for single or multiple applications and i s based on the methods of Hoerger and Kenaga (1972) as modified by Fletcher et al. (1994). Residue EECs were calculated for an application

rate at 0. 375 lbs a

. i

. /A (i.e., the maximum annual application rate allowed according to the label) applied one time over a single year

. As discussed in Section 3.1 , the typical application frequency of sulfometuron methyl is not well documented and expected to be highly variable depending on site conditions and the type of vegetation to be controlled . However, because application of sulfometuron methyl is limited to an annual maximum rate of no more than 0.375 lb a.i./A for its registered uses, a one

- time application at the maximum rate was chosen to represent a conservative estimate of th e EEC for wildlife dietary exposure. Residue data supporting a specific value for foliar dissipation half

- life were not available for sulfometuron (e.g., total magnitude of residue [171

- 4], reduction of residue [171.5], and foliar dissipation [132

- 1]). Al though the default foliar dissipation default half

- life of 35 days ( Willis and

McDowell

, 1987) would apply to sulfometuron methyl, a foliar dissipation half

- life was not used since only one application event was modeled.

The EECs on terrestrial food ite ms may be compared directly with dietary toxicity data or

converted to an oral dose and compared to dose

- based toxicity data. Th is screening

- level risk

assessment for sulfometuron methyl uses estimated upper bound (i.e., 90 th 

### percentile) residues as

the in itial measure of exposure. For comparisons with avian and mammalian dietary

- based toxicity data, the maximum predicted upper bound residues of sulfometuron methyl are used directly without adjustment ( Table 17 ) . For a single app lication season, these EECs are considered to represent an estimate of the upper bound exposure following sulfometuron methyl

### 54 application at the maximum label rate. For comparisons with dose

- based toxicity data, EECs are adjusted to an average daily dose (mg/kg

- bw/d) using standard allometric relationships. Additional information on the modeling of sulfometuron methyl exposure to terrestrial animals is provided in APPENDIX F : T

- REX Output

Table 17 . Unadj usted Dietary Terrestrial EECs for Birds and Mammals Following Sulfometuron Methyl Spray Application For Non

- Crop Vegetative Management.

Uses # of App. x App. Rate (application method) Food Items Upper Bound EECs (ppm)

Non

- Crop Vegetative Management 1 1 x 0.375 lb a.i./A ( ground broadcast ) Short Grass

Tall Grass Sm. Insects, Broadleaf Plants Lg. Insects, Fruits, Pods 90.0

41.3

50.6

5.6

1 Includes uses on unimproved turf, forestry (Christmas trees & other conifer plantations), non

- crop vegetative manage ment including roadsides, railroads and industrial sites



### Terrestrial Plants. For non

- target plants, exposures to sulfometuron methyl are considered most likely to occur as a result of spray drift and/or runoff from aerial and ground applications. Spray

d rift and runoff are important factor s in characterizing the risk of sulfometuron methyl to non

target plants, which is assumed to reach off

- site areas

. T wo different models were used to evaluate impacts on terrestrial plants:

1. TerrPlant, which focuses mor e on selection of the environmental setting for exposure and the combined contributions from runoff and spray drift; and

2. AgDRIFT, which focused on evaluation of the effects of different application procedures

o n spray drift; only environmental concentratio ns from spray drift are measured. AgDRIFT is designed to provide quantification of spray drift amounts at distances of less

than 1000 feet from the treatment area.

The TerrPlant model (Ver.1.2.2 ) predicts EECs for terrestrial plants located in dry and sem i

aquatic areas adjacent to the treated areas. The EECs are based on the application rate

, solubility of the pesticide in water and drift characteristics, which depend on application method

. Different loading ratios are used for runoff to dry and semi

- aq uatic areas. For dry areas, pesticide runoff exposure is estimated as sheet runoff. In the model, sheet runoff is defined as the amount of pesticide in water that runs off of the soil surface of a treated field which is equal in size to the

non

- target ar ea (1:1 ratio of areas)

. For semi

- aquatic areas, runoff exposure is estimated as channelized runoff. In the model, channelized runoff is the amount of pesticide that runs off of a treated field 10 times the size of the area adjacent to the treated field (10:1 ratio of areas)

.

According to the TerrPlant model, t he amount of sulfometuron methyl that runs off is a proportion of the application rate and is assumed to be 5% based on a solubility of >100 mg/L for sulfometuron methyl in w ater (pH 7 or above) . Drift from aerial applications is assumed to

be 5 % of the application rate , whereas drift from ground spray applications is assumed to be 1% (this differs from AgDRIFT, for which spray drift is not predefined)

. Predicted terrestrial plant

### 55 EECs (expressed as a fraction of the application rate) following single, aerial and ground spray application at the maximum application rate of sulfometuron methyl a re summarized in Table 18

. Details on inputs and outputs f rom the TerrPlant model are provided in “ APPENDIX D: Terrplant Spreadsheet ”.

Table 18

. EECs for Terrestrial Plants Located Adjacent to Sulfometuron Methyl (aerial and ground spray application) Treated Sites.

Terrestrial Use Application

Method (Non

- granular) EEC (lbs ai/A)
Total Loading to Dry Areas Adjacent

to Treated Areas 2 Total Loading to Semi

Aquatic Areas Adjacent

to Treated Areas 3 Drift to Adjacent Areas 4

Vegetative

management 1

(1 x 0.375 l b ai/A) Aerial 0.038 0.21 0.019

Ground (unincorporated) 0.023 0.19 0.0038

1 Includes uses on unimproved turf, forestry (Christmas trees & other conifer plantations), non

- crop vegetative management including roadsides, railroads and industrial sites

2 EE C = Sheet Runoff + Drift (5% for aerial or 1% for ground) assuming 1:1 runoff loading ratio

3 EEC = Channelized Runoff + Drift (5% for aerial or 1% for ground) assuming 10:1 runoff loading ratio

4 EEC for aerial (appl. rate x 5% drift) or ground applicatio n (appl. rate x 1% drift)



### Because sulfometuron methyl is an herbicide, a more in

- depth spray drift exposure assessment utilizing Tier I and II 5



### TABLE 20 AgDRIFT® (version 2.01) modeling is also provided to better characterize potential exposure of terrestrial pla nts. AgDRIFT® utilizes empirical data to

estimate off

- site deposition of aerial and ground applied pesticides, and acts as a tool for evaluating the potential of buffer zones to protect sensitive habitats from undesired exposures. contains EECs at several distances from the edge of the field.

A total of four different application scenarios were modeled (Columns labeled [ A ] through [ D ] ) to illustrate predicted spray deposition of sulfometuron at various distances from th e edge of the

field under:

1. what may be characterized as typical applications that mostly follow best management practices (that are recommended on the sulfometuron label)

– columns A and C.

2. Reasonable worst case assumptions following use scenarios that a re not necessarily typical or recommended, but are plausible and permitted on the label. See columns B and

D.

For g round applications , there is only a “Tier 1” module in AgDRIFT, but there are some input options still available to vary

. For this asses sment, o nly the boom height was varied between the

5 Note that the AgDRIFT Tier I and II terminology should not be confused with the Tier 1 and 2 used for most other EFED models. In AgDRIFT, Tier I refers to an operating mode with more limited options and Tier II refers to a mode where there is much more user access to selection of model inputs. Unlike with most EFED models, a Tier I A gDRIFT assessment should not be presumed to represent more conservative (higher exposure) scenarios than those represented in a Tier II AgDRIFT assessment.

### 56 ground spray scenario [A] (0.51 meter height) and the scenario [C] (1.27 m height). Other key assumptions in the ground application spray drift modeling include:

1. Drop Size Distribution: ASAE very fine to fine classification (ASAE is now ASABE: the American Society of Agricultural and Biological Engineers)

2. Number of swaths = 20

3. Swath Width = 45 feet

4. Application Efficiency (20 rows): 97.96 %

5. Use of the 90 %ile upper bound numbers from the empirical data se t which is the basis of AgDRIFT spray drift estimates.

Aerial applications were simulated with the AgDRIFT tier 2 module, which allowed incorporation of some the best management practices to minimize spray drift recommended (but not mandated) on product l abels. The more high

- end exposure use condition assumptions for aerial applications in scenario [ B ] are given in Table 19

. Factors varied for the more typical

- use scenario [D] with some best

- management practices include:

1. Wind speed of 10 mph

2. ASAE droplet size of fine to medium

3. Temperature = 86 deg F

4. Relative Humidity = 75 percent

5. Boom Height = 10 feet

The model results demonstrate a several fold to 30

- fold difference in the percentage and amount of sulfometuron deposited off

- s ite (the percentage difference between estimates with each scenario increases with increasing distance from the targeted field); see TABLE 20 and TABLE

21

.

Table 19 . Selected A g DRIFT inputs for high

- end exposure from aerial applications of sulfometuron methyl using best management practices

.

Input type Input value Justification

Aircraft Air Tractor AT

- 401 Commonly used aircraft. Typical size and weight . Aircraft type does not greatly affect drift.

Boom length 76.3% of wingspan Recommended to reduce drift and increase application efficiency. Greater boom lengths generate more drift. 3/4 wingspan should be specified on the label.

Release (boom)

h eight 15 ft. Estimated upper bound under normal conditions. Should be specified on labels with no

- spray zones.

Flight lines 20 Approximate standard scenario field size.

### 57 Swath width 60 ft. Typical. Does not greatly affect drift.

Swath displ acement fraction (as a

fraction of the swath width) fine: 0.6833 Swath offset is good application practice. The value used results in 50% deposition at the edge of the field.

Drop size

D istribution Fine (ASAE definition) Dependent upon produc t.

Spray material 50% water

50% nonvolatile Dependent on tank mix. Calculate nonvolatile rate based on the portion of the tank mix which is not easily evaporated (e.g. the fraction that is not water or high vapor pressure solvent). Wind speed (at 2 meters above

the surface. 15 mph Typical wind speed varies greatly with geographic region and other factors. Ten mph is an adequate, high drift, input for many areas. Model runs for the plains states may require higher wind speeds. Wind speed limitat ions should be specified on the label.

Humidity 50% Conservative input adequate for much of the US. Extreme values may significantly affect drift levels under certain conditions.

Temperature 86 degrees F Conservative input adequate for much of the US. Extreme values may significantly affect drift levels under certain conditions.



### TABLE 20 . ESTIMATED PERCENT AGE OF SULFOMETURON METHYL
SPRAY DRIFT FROM GRO UND OR AERIAL APPLIC ATIONS AT VARIOUS
DISTANCES FROM A TRE ATED FIELD.

DISTANCE

DOWN

WIND (FEET) [A] GROUND

APPLICATION (LOW BOOM) [B] GROUND

APPLICATION (HIGH BOOM) [C] AERIAL (FOLLOWING MANY

LABEL RECOMMENDATIONS) [D] AERIAL (HIGH

- END

EXPOSURE SCENARIO)

Percent Percent Percent Percent

0 102.0 106.0 50.00 77.35

50 1.77 5.00 17.12 38.32

100 0.95 2.48 9.79 25.11

200 0.51 1.20 4.69 14.07

500 0.21 0.39 1.92 5.40

750 0.13 0.22 1.39 3.82

900 0.11 0.17 1.24 3.32

### 58 TABLE 21 . ESTIMATED AMOUNT OF SULFOMETURON METH YL SPRAY DRIFT

FROM GROUND O R AERIAL APPLICATION S AT VARIOUS DISTANC ES FROM A

FIELD TREATED WITH THE MAXIMUM LABELED RATE OF 0.375 LB AI/ A.

DISTANCE

DOWN

WIND (FEET) [A] GROUND

APPLICATION (LOW BOOM) [B] GROUND

APPLICATION (HIGH BOOM) [C] AERIAL (FOLLOWIN G

MANY LABEL

RECOMMENDATI ONS) [D] AERIAL (HIGH

- END

EXPOSURE SCENARIO)

Lbs ai/A Lbs ai/A Lbs ai/A Lbs ai/A

0 0.3822 0.3956 0.1874 0.2900

50 0.0066 0.0187 0.0642 0.1437

100 0.0036 0.0093 0.0367 0.0941

200 0.0019 0.0045 0.0176 0.0527

500 0.0008 0.0015 0.0072 0.0203

750 0.000 5 0.0008 0.0052 0.0143

900 0.0004 0.0006 0.0046 0.0125



### The AgDRIFT results illustrate the importance of droplet size in controlling spray drift. Using larger droplet sizes, such as coarse or extremely coarse spraying, reduces the downwind drift to adjac ent areas compared to when medium or fine spraying is used. Reducing boom height during application and applying when wind speeds are between 3 and 10 mph are also important in controlling drift.

3.2.3.2. Residue Studies

Environmental residue studies can also pr ovide useful information regarding the potential exposure of terrestrial wildlife receptors. This data can be used to corroborate modeling results or to provide additional insights into chemical fate with respect to exposure. For sulfometuron methyl , no studies are available; all estimates of exposure are based on modeling efforts

3.2.4. Uncertainties and Limitations for this Exposure

Assessment

3.2.4.1. Limitations In Knowledge Of Actual Use Patterns

Knowledge on the s pecific regions of use of sulfometuron methyl is limited. The use pattern of sulfometuron methyl does not lend itself to easy characterization geographically: There are a variety of vegetation management uses on sites that are less clearly defined than agricultural

### 59 crops and have disjoint or unusual tre atment area configurations (e.g., as with rights of way and railroad uses, or industrial site grounds).

Practical limits on usage rates long

- term at particular sites may different from legally allowable use levels (e.g., usage is highly unlikely to occur every year at a particular site even though this is allowable under the label language).

3.2.4.2. Variability In Sulfometuron Environmental Persistence

Sulfometuron methyl persistence is s ignificantly affected by soil or water chemistry and may not always easy to predict from typically available soil / water property data alone

. A clearer picture of the range of variability in sulfometuron methyl persistence in the environment would require environmental fate studies on a greater variety of soils / waters / sedim ents with a greater range of pH levels and other soil properties. This is particularly true for the aerobic soil and anaerobic aquatic metabolism studies

.

3.2.4.3. Exposure To Sulfometuron Methyl Degradates

Limitations in environmental fate data for the degradat es made specific modeling for exposure to each of the degradates very problematic. The data on individual degradates, environmental persistence and mobility is insufficient to model each compound separately. This may not provide realistic estimates with t he PRZM / EXAMS models which utilize a receiving pond with

no turnover or outflow of residues. If any of the degradation products of sulfometuron methyl should be found to be of toxicological concern at potential environmental exposure levels, than

additio nal data and exposure assessment specific to the degradates of concern would be needed.



## 3.3. ECOLOGICAL EFFECTS CHARACTERIZATION

In screening

- level ecological risk assessments, the ecological effects characterization describes the types of effects a pesticid e can potentially produce in an animal or plant. The toxicity data used in the effects characterization for sulfometuron methyl are derived primarily from registrant

- submitted toxicity s t udies that are conducted (and reviewed) according to OPP test guidel ines. These “guideline” studies are also supplemented by data reported in the USEPA

ECOTOX database that have met Agency criteria for acceptability.

Toxicity testing reported in this section does not include all species potentially affected by

sulfomet uron methyl usage. Only a few surrogate species for fish, aquatic invertebrates and birds are used to represent all species in the United States. For mammals, effects are typically extrapolated from laboratory rat studies . Also, neither reptiles nor amp hibians are tested

, although data from reptiles and amphibians may be available from the literature as reported in

ECOTOX. In absence of such data, t he risk assessment assumes that avian and reptilian and

terrestrial

- phase amphibian sensitivities to the c hemical are similar. A similar assumption is

made for fish as surrogates for aquatic

- phase amphibians. Terrestrial plant data are derived from the vegetative vigor and seedling emergence tests, typically conducted on 10 agricultural crop species, and do not account for potential chronic or reproductive effects. Lack of plant

### 60 reproduction data is part ic ularly relevant to sulfometuron methyl because some data suggest plant reproduction may be more sensitive to sulfonylurea herbicide exposure compared to gr owth

and endpoints measured in the seedling emergence and vegetative vigor tests ( Fletcher et al, 1993)

. For aquatic plants, five aquatic plant species (1 vascular, 4 nonvascular) are used to represent potential toxicity to all aquatic plant species.

Most of the studies with non

- target organisms were conducted with sulfometuron methyl technical (i.e., > 90% purity). These studies provide the effects basis for risk estimation. Registrant

- submi t ted studies of the acute, oral toxicity of end use product (Ou st ® 

### ) were available only for rats. Other toxicity studies of end

- use product were obtained from ECOTOX for selected aquatic invertebrates and terrestrial plants. Details of each of the guideline and literature studies of sulfometuron methyl effects on n on

- target organisms are provided in

“ APPENDIX H: Ecological Effects Data Summaries .”

Toxicological information on the primary degrad at es of sulfometuron methyl (e.g., p yrimidine

amine , p yrimidine

- ol , saccharin

, s ulfonamide ) appea rs very limited. Specifically, no guideline toxicity studies with ecologically relevant endpoints (e.g., growth, reproduction, development, survival) were identified for the primary degradates of sulfometuron methyl . Based on literature

searches conducte d with ECOTOX, toxicological studies were identified only for one major degradate (saccharin). Of the nine saccharin studies identified in ECOTOX, all were considered inapplicable to the ecological risk assessment because they lack evaluation of saccharin effects using ecological ly relevant endpoints (e.g., survival, growth, reproduction, development). This finding is not surprising given the role of saccharin as a sugar substitute and the corresponding toxicological focus on measures of effect that perta in to human health (e.g., biochemical, organ

level, mutagenicity and carcinogenicity assays). A summary of the ecological toxicity studies involving the saccharin metabolite of sulfometuron methyl is provided in “ APPENDIX H:

Ecolo gical Effects Data Summaries

. ” Appendix J contains the results of the ECOTOX literature search with respect to those studies found to be acceptable to ECOTOX but not OPP for the purposes of this risk assessment.

Table 22 contai ns a summary of the most sensitive ecological effects endpoints used in this risk

assessment . As expected, the acute toxicity of sulfometuron methyl to animals is very low (slightly to practically non

- toxic) while its toxicity to plants is very high. Thi s finding is consistent with the mode of action of sulfometuron methyl (inhibition of ALS) and is similar to toxicity findings from other sulfonylurea herbicides.

### 61 Table 22

. The Most Sensitive Endpoints Used In The Sulfometuron M ethyl Screening

- Level Risk Estimation.

Environment Taxa Type of

Risk Type of Endpoint Endpoint Units MRID

Aquatic Freshwater

Fish Acute LC 50 > 148 mg ai/L 435018

- 02

Chronic NOAEC Data gap (A)

Freshwater

Invertebrates Acute EC 50 > 150 mg ai/L 43501 8

- 03

Chronic NOAEC 97 mg ai/L 416728

- 06 ( A )

Saltwater Fish Acute LC 50 > 45 mg ai/L 416728

- 03

Saltwater

Invertebrates Acute EC 50 > 38.2 mg ai/L 416728

- 04

Plants Non

- Listed EC 50 0.48 μg ai/L 435385

- 03

Listed NOAEC 0.21 μg ai/L 435385

- 03

Terr estrial Avian Acute LD 50 > 4650 mg ai/kg

- bw 245375

Acute LC 50 > 4600 mg ai/kg

- diet 00071414

Mammalian Acute LD 50 > 5000 mg ai/kg

- bw 430892

- 01

Chronic NOAEC > 300 mg ai/kg

- bw/d 78798

Plants Non

- Listed EC 25 1.8 x 10 - 5 lb ai/A 435385

- 01 (A)

L isted EC 5 ( B ) 9.9 x 10

- 7 lb ai/A 435385

- 01 (A)

( A ) Toxicity value was revised after a re

- review and analysis of the study results in 2007. ( B ) EC5 was used for estimating effects to listed (endangered) terrestrial plants because the NOAEC equaled or exceed ed the EC 25 , as discussed

in the terrestrial effect characterization section.



### 3.3.1. Aquatic Effects Characterization

3.3.1.1. Freshwater Fish, Acute

Acute toxicity studies with the technical grade active ingredient (TGAI) were required for two freshwater fish species for sulfometuron methyl. Preferred test species are bluegill sunfish (warm water fish) and rainbow trout (cold water fish). Based on results from preliminary range finding tests, definitive toxicity t ests were not required for bluegill or rainbow trout (i.e., LC 50 

### >200 mg ai/L). Therefore, toxicity ‘limit’ tests were conducted at a single test concentration of 150 mg ai/L (bluegill, MRID 435018

- 01 ; rainbow trout, 435018

- 02 ).

Results from these stud ies are summarized in Table 23 and indicate that sulfometuron methyl is practically non

- toxic to freshwater fish on an acute toxicity basis. No mortality was reported in the test concentration of 150 mg ai/L (nomi nal) and measured concentrations were within 80

- 120% of nominal concentrations in both tests. To prevent formation of insoluble precipitate, the pH of test solutions were buffered w/ addition of sodium hydroxide, which resulted in pH values

that exceeded guideline recommendations (up to pH 9.0). The authors report no formation of precipitate or solubility problems in test solutions and no mortality in pH buffered controls. The

### 62 pH range deviation is therefore considered a necessary byproduct of increasing the solubility of the test chemical. All other test guideline deviations are considered minor. Th ese stud ies are classified as acceptable and meet the guideline requirements for an acute toxicity study with

warm water and cold water f ish.

Table 23

. Freshwater Fish Acute Toxicity of Sulfometuron Methyl

.

Guideline Species % ai 96

- hour

LC 50 (mg/L) Toxicity Category MRID No.

Author/Year Study

Classification

72

- 1 Bluegill sunfish (Lepomis macrochirus) 9 9.6 > 150 Practically

non

- toxic 435018

- 01

Brown (1994a) Acceptable

72

- 1 Rainbow trout (Oncorhynchus mykiss) 9 9.6 > 148 Practically

non

- toxic 435018

- 02

Brown (1994b) Acceptable



### 3.3.1.2. Freshwater Invertebrates, Acute

The toxicity of sulfometuron methyl to freshwater invertebrates is indicated by a 48

- hr acute toxicity test with the water flea, Daphnia magna (MRID 435018

- 03 ; Table 24 . As observed with freshwater fish, no mortality was observed in a range finding test up to 200 mg ai/L or the

follow

- up to xicity limit test at 150 mg ai/L. Buffering of test solutions was required to prevent formation of precipitates which resulted in a greater pH range (8.4

- 9.0) than recommended (7.2

- 7.6). No mortality was observed in the 150 mg/L treatment or in the negat ive control. One daphnid died in the pH adjusted control (mortality 3%). The test concentration was measured and found to be 100% of nominal. The pH range deviation is therefore considered a necessary byproduct of increasing the solubility of the test ch emical. This study was originally classified as ‘supplemental’ by EFED in 1995 because of concerns over chemical composition of the

dilution water. A re

- review of this study in conjunction with other data on the dilution water from a separate study with the same lab indicates that it is acceptable. A detailed study review and explanation of the study reclassification are provided in “ APPENDIX H: Ecological Effects

Data Summaries .”

Table 24

. Freshwater Invertebrate Acute Toxicity of Sulfometuron Methyl

.

Guideline Species % ai 48

- hour

LC 50 (mg/L) Toxicity Category MRID No.

Author/Year Study

Classification

72

- 2 Water flea ( Daphnia magna ) 9 9.6 > 150 Practically

Non

- toxic 435018

- 03

Brown (1994c) A cceptable (1)

(1) reclassified as acceptable for this risk assessment, see APPENDIX H: Ecological Effects Data Summaries for details.



### 3.3.1.3. Estuarine and marine Fish, Acute

The toxicity of sulfometuron methyl to estua rine and marine fish is indicated by a 96

- hr acute toxicity test with the sheepshead minnow, Cyprinodon variegat u s conducted at nominal

### 63 concentrations ranging from 15 to 100 mg ai /L (MRID 416728

- 03

, Table 25 . The LC 50 

### based on measured concentrations from this study was found to be greater than 45 mg ai/L. No mortality or observable signs of sublethal effects occurred in the study except for one dead fish (5%) at 8.2 mg/L (measured).

This study was re

- reviewed for this risk assessment and found to contain several significant deficiencies which render its classification as supplemental. Specifically, measured concentrations ranged widely from test initiation to termination (4 to 7 times), which is believed

due t o the formation of an observable precipitate in test solutions. This occurred despite buffering of the dilution water to an initial pH of 8.5 (pH ranged thereafter from 7.4 to 8.5). Although these deficiencies could render the study classification as “un acceptable,” it is considered to provide some useful information in this risk assessment (i.e., an indication of a lack of toxicity at or near solubility limits in test solutions). Furthermore, when viewed in the context of screening level EECs (i.e., a m aximum peak concentration of 0.031 ppm in water,

Table 15 ) , the bioavailable (dissolved) portion sulfometuron methyl would have to be approximately 1500

- fold lower than the highest measured test concentration (~45 ppm) in order

fo r risks to be evident. Therefore, this study is classified as supplemental but is not recommended for repeat testing at this time because a repeat test would be highly unlikely to

alter the risk assessment conclusions.

Table 25

. Estuarine/Marine Fish Acute Toxicity of Sulfometuron Methyl

.

Guideline Species % ai 96

- hour

LC 50 (mg/L) Toxicity Category MRID No.

Author/Year Study

Classification

72

- 3 Sheepshead minnow (Cyprinodon variegatus) 9 9.1 > 45 > Slightly

toxic 416728

- 03

Ward and Boeri (1990a) Supplemental ( 1 )

( 1 ) Reclassified as supplemental for the purposes of this risk assessment. See APPENDIX H: Ecological Effects Data

Summaries for additional study details.



### 3.3.1.4. Estuarine and marine Invertebrates, Acute

The toxicity of sulfometuron methyl to estuarine and marine invertebrates is indicated by acute toxicity tests with mysid shrimp, Mysidopsis bahia , and embryo/larvae of the eastern oyster, Crassostrea virginica

. For mysids, a 96

- h assay was conducted at nominal concentrations ranging from 15 to 100 mg/L. The 96

- h LC 50 

### based on measured concentrations from this study was found to be greater than 44.8 mg ai/L. No mortality or observable signs of sublethal effects

occurred in t he study at any test concentration or the control. For oysters, a 48

- h assay was conducted on embryos at the same nominal concentrations as used for mysids. The 48

- h EC 50 

### based on measured concentrations for this study was found to be greater than 38.2 m g ai/L. No mortality occurred and 99% of the surviving control oysters were normal.

A re

- review of both the mysid and oyster studies indicates they have several significant deficiencies which render their classification as supplemental. Specifically, measured concentrations of sulfometuron methyl ranged widely from test initiation to termination (3X to 13X in the mysid tests; 3X in the oyster test) and were substantially below nominal

concentrations. The low % nominal is believed due to the formation of an observable precipitate

### 64 in test solutions. In the mysid test, low % nominal occurred despite buffering of the dilution water to an initial pH of 8.5 (pH ranged thereafter from 7.6 to 8.5). In the oyster test, pH ranged from 7.7 to 8.0. The pH range in both the mysid and oyster tests extended beyond the recommended range for test guidelines (7.7

- 8.0 for euryhaline shrimp; 8.0

- 8.3 for stenohaline oysters).

Although these deficiencies could render both study classifications as “unacceptable,” they are considered to provide some useful information in this risk assessment (i.e., an indication of a lack of toxicity at or near solubility limits in test solutions). Furthermore, when viewed in the context of screening level EECs (i.e., a maximum peak concen tration of 0.031 ppm in water,

Table 15 )

, the bioavailable (dissolved) portion sulfometuron methyl would have to be approximately 1 3 00

- fold lower than the highest measured test concentration (~ 40 ppm) in order

for risks to be evi dent. Therefore, this study is classified as supplemental but is not

recommended for repeat testing at this time because a repeated test would not likely affect the

risk assessment conclusions.

Table 26

. Freshwater Invertebrate A cute Toxicity of S ulfometuron Methyl

.

Guideline Species % ai 96

- hour

LC 50 or 48

- h EC 50 (mg/L) Toxicity Category MRID No.

Author/Year Study

Classification

72

- 3 Mysid shrimp (1)

( Mysidopsis bahia ) 9 9.1 > 44.8 > Slightly

toxic 416728

- 04

Ward and Boe ri (1990c) Supplemental ( 2 )

72

- 3 Eastern oyster (1)

(C rassostrea virginica ) 9 9.1 > 38.2 > Slightly

toxic 416728

- 05

Ward and Boeri (1990b) Supplemental ( 2 )

(1) 96

- h LC 50 applies to mysids; 48

- h EC 50 applies to oyster.

( 2 ) Reclassified as supplemental for the purposes of this risk assessment. See APPENDIX H: Ecological Effects Data

Summaries for additional study details.



### 3.3.1.5. Freshwater Fish, Chronic

No acceptable or supplemental data on the chronic toxicity of sul fometuron methyl to freshwater

fish were available. A chronic, early life

- stage toxicity test was conducted in 1982 to determine the effect of sulfometuron methyl on fathead minnow embryo hatching, larval survival, and growth (MRID 423857

- 04; Accession No . 249796) , however upon further review, this study was classified as unacceptable.

3.3.1.6. Freshwater Invertebrate, Chronic

The c hronic toxicity of sulfometuron methyl to freshwater invertebrates is indicated by a 21

- day life cycle test conducted on the water f lea, Daphnia magna (MRID 416728

- 06; Table 27 ). Daphnids (<24

- h old) were exposed to six concentrations of sulfometuron methyl ranging from 0.1 to 100 mg/L (nominal) in a static

- renewal system. In order to promote solubility of the test substance, the pH of the stock solutions of the 25 mg/L and 100 mg/L treatments were adjusted with NaOH to pH 8.5. Both a negative and pH

- adjusted controls were included. Mean measured

### 65 concentrations were close to nominal concentra tions ( i.e., within 20% ), thus indicating that

v ariability in test concentrations was well within the acceptable limits of 1.5X. Survival and growth (length) were not affect ed at any test concentration. Reproduction, as measured by the

number of neonates produced/daphnid, was not significantly different from negative controls in any treatment (ANOVA, 0.05). Although the Dunnett’s multiple comparison test indicated a marginally significant difference in the 24 mg/L treatment (mean measured concentration), it is not considered statistically valid to apply means testing when ANOVA results indicate lack of significant differences among treatments. Furthermore, an inconsistent concentration

- response relationship is indicated by the lack of a significant reduc tion in daphnid reproduction at 97 mg/L (the highest treatment tested). Therefore, the NOAEC for daphnid reproduction is re

- interpreted as 97 mg/L (unbounded) and the LOAEC is > 97 mg/L. This study is classified as acceptable and meets the guideline requ irements for a chronic study using a freshwater invertebrate.

Table 27 . Freshwater Aquatic Invertebrate Chronic Toxicity for Sulfometuron Methyl

.

Species/

Static Renewal % ai 21

- day NOAEC /

LOAEC (mg/L) (1) Endpoints Affected MRID No.

Author ( Year ) Study

Classification

Water flea (Daphnia magna) 9 9 .1 97 / >97 R eproduction 416728

- 06 Baer (1990) Acceptable

(1) NOAEC and LOAEC were re

- analyzed as part of this risk assessment. See Appendix H for additional study details.



### 3.3.1.7. Aquatic Animal Sublethal Effect s : Formulated Product and Degradate Toxicity

No signs of toxicity or sublethal effects were o bserved in the acute or chronic toxicity tests of sulfometuron methyl that were described previously in this Exposure Characterization (considering acceptable and supplemental studies). This is not surprising, given that sulfometuron methyl is practically nontoxic on an acute toxicity basis.

Two studies of the toxicity of sulfometuron methyl in formulated product (e.g., Oust ® 

### ) to aquatic animals were identified and discussed further below. The first study, Naqvi and Hawkins (1989) exposed four genera o f field

- collected microcrustaceans ( Diaptomus sp. Eucyclops sp., Alonella sp., and Cypria sp. ) to sulfometuron methyl from the Oust ® 

### formulated product at nominal concentrations of ranging from 100 to 2500 mg/L for 48

- h. Consistent, monotonic exposure

res ponse relationships across the six treatments occurred for all four species and 48

- h LC 50 

### s (probit analysis) were reported as follows:

Species Test

Chemical 48

- h LC 50 

### (mg/L) (95% confidence limits) Classification Reference

Diaptomus sp.

Oust ®

(~93% ai) 1315 (1207

- 1524) supplemental Naqvi and Hawkins (1989) Eucyclops sp. 1320 (1154

- 1536)

Alonella sp. 802 (475

- 928)

Cypria sp 2241 (1744

- 4517)

### 66 This study is classified as supplemental primarily because test concentrations were not measured in the study and the field collec ted test organisms were provided a relatively short application period (96

- h) vs. the 7

- d minimum acclimation period recommend for freshwater invertebrate testing. Furthermore, organisms were not positively identified to t he species level, thus indicating that more than one test species may have been tested in each study. Finally, the study authors do not indicate whether nominal concentrations were adjusted to reflect the percent active ingredient in the formulated produc t. Assessment of the relative acute toxicity of sulfometuron methyl as technical grade and in formulated to aquatic animals is somewhat

uncertain because LC 50 

### and EC 50 

### values were not achieved for the technical grade herbicide (e.g., EC 50 

### and LC 50 

### varied from >38 to >150 mg ai/L). However, results from the Naqvi and Hawkins (1989) study indicate that sulfometuron methyl formulated in Oust ® 

### is practically nontoxic to aquatic microcrustaceans. Thus, the comparative toxicity of technical grade

sulfometuron methyl and sulfometuron methyl formulated at least appear similar in terms of both ingredients being practically nontoxic to aquatic invertebrates.

The second study was submitted by the registrant (DuPont) per FIFRA Section 6(a)2 requirements on July 1, 1991. In this study, Romaire (1984) evaluated the acute toxicity of

Oust ® 

### (% ai not reported) to juvenile red swamp crayfish, Procambarus clarkii . A static, acute toxicity study was conducted for 96 hours in 4 replicate aquaria (5 crayfish/aquarium) at 8 test concentrations ranging from 0 to 10,000 mg ai/L. Analytical measurements of sulfometuron methyl were not taken during the study. The authors report that the 96

- h LC 50 

### was > 5,000 mg ai/L for sulfometuron methyl and mortality did not exceed 50% in a ny test treatment. However, review of this study indicates that it is unacceptable because dissolved oxygen levels dropped precipitously throughout the study in test concentrations where mortality was observed, despite periodic aeration of test solutions. Dissolved oxygen levels repeatedly reached levels as low as 2.1 mg/L or approximately 25% saturation, which is well below ASTM recommendations of 60% saturation. Because the effect of dissolved oxygen on crayfish mortality could not be separated from th e possible effects of sulfometuron methyl, this study is not considered scientifically sound for the purposes of describing the acute toxicity of sulfometuron methyl to juvenile crayfish.

Regarding the aquatic toxicity of sulfometuron methyl degradates t o aquatic animals, a literature search conducted in May, 2007 of EPA’s ECOTOX database revealed no acceptable or supplemental studies that described the toxicity of major sulfometuron metabolites: pyrimidine amine, pyrimidine

- ol, saccharin , and sulfonamide

. A list of studies considered acceptable to ECOTOX but not OPP is provided in “ APPENDIX J: Ecological Effects Studies Rejected by

OPP .”

3.3.1.8. Field Studies

No field studies (e.g., mesocosm and micro cosm studies) were found concerning the aquatic toxicity of sulfometuron methyl, either based on OPP guidelines or from the aforementioned

search of the ECOTOX database.

### 67 3.3.1.9. Aquatic Plants

A quatic plant toxicity studies using the TGAI are required to estab lish the toxicity of sulfometuron methyl to non

- target aquatic plants ( Table 28 ). Studies in five species are required for herbicides: freshwater green alga ( Selenastrum capricornutum ) , blue

- green algae (Anabaena flos

- aquae)

, a f reshwater diatom ( Navicula pelliculosa) , a marine diatom (Skeletonema costatum) , and duckweed (Lemna gibba)

. Of the four non

- vascular species tested, the green alga

is the most sensitive non

- vascular aquatic plant. This finding is consistent with the tox icity of flazasulfuron, another sulfonylurea herbicide with the same mode of action ( DP Barcodes:
D302482, D302484 ; EFED New Chemical review dated 4/ 11 /2007).

The EC 50 

### (reduction in cell density) for S. capricornutum is 4.6 μg ai /L and the NOAEC is 0.63

u g ai/L. At the LOAEL of 1.3 μg/L, growth was reduced approximately 20%, while the cell growth at the NOAEC showed a slight increase relative to controls. These toxicity values are based on reported nominal concentrations. Although the study authors indi cate that samples were taken for analytical measurement and would be analyzed “if deemed necessary,” results from chemical analysis were not provided in the study report. At these concentrations, solubility of the test compound is not expected to be proble matic.

Preliminary tests with the two diatom species indicated that Tier II tests would not be necessary. Based on results from Tier 1 tests, growth (cell density) of neither diatom was affected significantly relative to controls at measured concentrat ions of 370 μg/L and 410 μg/L (i.e., the maximum values calculated for sulfometuron methyl applied directly to a 6 in ch deep pond

. Measurements at test initiation and termination indicate stability of sulfometuron methyl in the

test solutions.

A tier 2 t est was conducted on the freshwater blue

- green algae, Anabaena flos

- aquae
, at
measured test co ncentrations ranging from 14 to 180 μg/L. Measurements at test initiation and termination indicate stability of sulfometuron methyl in the test solutions. An EC 5 0 

### of 4 1. 6 μg/L (cell density) is calculated for Anabaena and a NOAEC of <14 μg/L (lowest test concentration). This NOAEC corresponds to a 20% reduction in cell growth relative to controls. This study is considered scientifically sound but classified as supplemental because a NOAEL was not

determined.

The 14

- day EC 50 

### and NOAEC for the freshwater vascular plant (duckweed) for frond count (the most sensitive endpoint tested) are 0.48 and 0.21 μg/L, respectively, based on exposure to

measured concentrations ranging from 0.13 to 1.05 μg/L. Frond counts were reduced 4% at the

NOAEC and 20% at the LOAEC. Measurements at test initiation and termination indicate stability of sulfometuron methyl in the test solutions.

Except for the test with blue

- green algae, t he toxicity studies of aquatic plants ( Table 28 ) are classified as acceptable and meet the guideline requirements for toxicity tests with aquatic vascular and nonvascular plants. Toxicity values for the most sens itive species ( green algae and

duckweed ) w ill be used to calculate risk quotients.

### 68 Table 28 . Non

- target Aquatic Plant Toxicity for Sulfometuron Methyl.

Species % ai EC 50 / NOAEC ( μ g/L) Endpoints

Aff ected MRID No.

Author ( Year ) Study

Classification



### Vascular Species: Duckweed

Duckweed ( Lemna gibba ) 95.7 0.48 / 0.21 Frond Count i 435385

- 03

Kannuck (1995) Acceptable



### Non

- Vascular Species: Algae and Diatoms

Green Algae (1)
(Selenastrum capricornutum) 99 .1 4.6 / 0.63 Cell Density 416801

- 02

Hobert (1990) Acceptable

Blue

- green Algae (1)

( A. flos

- aquae ) 99.2 41.6 / <14 Cell Density 435385

- 02

Thompson (1994) Supplemental

Fresh Water Diatom (2)

( Navicula pelliculosa ) 99.2 >370 Cell Density 435385

- 02

Thompson (1994) Acceptable

Salt Water Diatom (2 )

( S keletonema costatum ) 99. 2 >410 Cell Density 435385

- 02

Thompson (1994) Acceptable

(1) Tier II definitive test

(2 ) Tier I screening test



### 3.3.2. Terrestrial Effects Characterization

3.3.2.1. Acute Effects on Birds

An acute oral toxicity study using the technical grade of the active ingredient is required to establish the acute toxicity of sulfometuron methyl to birds. The preferred guideline test species

is either mallard du ck (a waterfowl) or bobwhite quail (an upland gamebird). An acute oral toxicity study with the mallard indicates sulfometuron methyl is practically non

- toxic on an acute basis, with a reported oral LD 50 

### > 4,650 mg ai/kg

- bw ( Table 2 9 ). No mortality occurred in any treatment and birds appeared normal throughout the 14

- d test period. Food consumption varied widely across treatments, but did not exhibit a dose

- dependent trend. Weight gain/loss also did

not exhibit a dose

- dependent tre nd within or across sexes. Weight gain in females may have been confounded by induction of the egg laying cycle by the photoperiod used. Lack of acute oral toxicity to birds is consistent with testing results from other sulfonylurea herbicides (e.g.,

fla zasulfuron, rimsulfuron). The guideline requirement (71

- 1) is fulfilled for an acute oral toxicity study with birds for sulfometuron methyl and the study (Accession No. 245 375 ) is classified as acceptable.

### 69 Table 29

. Avian Acute Oral Toxicity for Sulfometuron Methyl

.

Species % ai LD 50 (mg ai/kg

- bw) Toxicity Category Accession No.

Author ( Year ) Study

Classification

Mallard duck (Anas platyrhynchos) > 93 > 4,650 Practically

non

- toxic 245375 Dudeck and Bristol (1981) Acceptable



### Tw o dietary studies a re required to establish the subacute dietary toxicity of sulfometuron methyl

t o birds. The preferred test species are mallard duck and bobwhite quail. The submitted data indicates that sulfometuron methyl is practically nontoxic to ma llard and quail when administered via subacute, dietary exposure. The 8

- day acute dietary LC 50 

### values for bobwhite quail and mallard are > 5,620 mg ai/kg

- diet and > 4,600 mg ai/kg

- diet , respectively ( Table 30

. There was no mortal ity, signs of clinical toxicity, or abnormal behavior reported in the studies. The guideline (71

- 2) is fulfilled for a subacute dietary study with birds. The studies ( Accession No. 246409 and MRID 71414) are classified as acceptable.

Table 30

. Avian Subacute Dietary Studies for Sulfometuron Methyl

.

Species % ai 8

- Day LC 50 (mg ai/kg

- diet) Toxicity Category MRID No.

Author ( Year ) Study

Classification

Northern bobwhite quail (Colinus virginianus) 9 5 .2 >5 ,620 Practically

non

- toxic 246409 (1)

Beavers and Fink (1981) Acceptable

Mallard duck (Anas platyrhynchos) 9 2 >4,600 Practically

non

- toxic 71414

Hazelton Laboratories Inc (1980) Acceptable

(1) Accession number



### .

3.3.2.2. Acute Effects on Mammals

Wild mammal testing is required by the Age ncy on a case

- by

- case basis, depending on the results of lower tier laboratory mammalian studies, intended use pattern and pertinent environmental fate characteristics. In most cases, rat or mouse toxicity values obtained from the Agency's Health Effects Division (HED) substitute for wild mammal testing. For sulfometuron methyl, the acute toxicity of sulfometuron methyl (technical grade active ingredient) is indicated by an acute, oral toxicity study with the rat (MR ID 43089201 ; T able 31

. In this study, 5 male and 5 female rats were administered a single oral dose of 5000 mg ai/kg

- bw technical grade sulfometuron methyl (approx. 100% a.i.) in corn oil via gavage. Rats were observed for mortality, signs of ill health, pharmacologi c and toxicological effects for 14 days after dosing. No mortality occurred at 5,000 mg ai/kg

- bw and no clinical signs of toxicity were observed that were related to sulfometuron methyl exposure. Male and females continued to gain weight throughout the st udy. An acute, oral LD 50 

### value of >5000 mg ai/kg

- bw was determined from this study, indicating that sulfometuron methyl is categorized as practically non

- toxic (toxicity category IV) to small mammals on an acute oral basis. This finding is consistent wit h lack of acute oral toxicity observed with other sulfonylurea herbicides to rats (e.g., flaz a sulfuron). This study is considered acceptable and satisfies the guideline requirement (81

- 1) for an acute toxicity study with mammals.

### 70 Table 31

. Mammalian Acute Toxicity for Sulfometuron Methyl

.

Species % ai Toxicity Affected Endpoints MRID No.

Author (Year) Toxicity Category

Rat (Sprague

- Dawley) ~100 LD 50 > 5,000 mg ai/kg bw (males/females) Survival, weight gain, gross organ patholo gy 43089201

Dashiell and Sarver (1990) IV



### 3.3.2.3. Acute Effects on Terrestrial

- phase Amphibians, Reptiles
and Beneficial Insects

A honeybee acute contact study is required for sulfometuron methyl because its post

- emergence treatment use will likely result in ho neybee exposure. The acute contact LD 50 

### , using the honey bee, Apis mellifera , is a single

- dose laboratory study designed to estimate the quantity of toxicant required to cause 50% mortality in a test population of bees. For sulfometuron methyl, bees

were exposed at 5 treatments ranging from 13 to 100 μg ai/bee and included a solvent and negative control ( MRID 416728

- 10; Table 32 ) . Results indicate that sulfometuron methyl is practically non

- toxic to bees on an acute contact basis

. The contact 48

- h LD 50 

### for sulfometuron methyl is >100 μg ai/bee

. Cumulative mortality and immobility ranged from 4

- 8% in the

controls to 0

- 2% in the treatments. No overt signs of toxicity were observed in the study. The guideline (141

- 1) is fulfilled (MRID 416728

- 10 ).

Table 32

. Non

- Target Insects

- Acute Contact Toxicity for Sulfometuron Methyl

.

Species % ai LD 50 (μg ai/bee) Toxicity Category MRID No.

Author ( Year ) Study

Classification

Honey Bee (Apis mellifera) ~100 >100 (contact) Practically

non

- toxic 416728

- 10 Hoxter and Smith (1990) Acceptable



### No acceptable or supplemental terrestrial

- phase amphibian or reptile toxicity studies were

submitted or located in the open literature based on a search of the ECOTOX database.

3.3.2.4. Chronic Effects on Birds

Avian reproduction studies using the TGAI are required for pesticide registration if birds may be subject to repeated or continuous exposure to the pesticide, especially preceding or during the breeding season. The preferred te st species are mallard duck and bobwhite quail. No data ( 71

- 4 guideline or literature studies) were available on the reproductive toxicity of sulfometuron methyl to birds.

### 71 3.3.2.5. Mammals, Reproductive Effects

A combined 2

- generation reproduction /oncogenicity study and 2

- year chronic reproduction study with rats exposed to sulfometuron methyl was submitted to the agency (MRID 423857

- 05 and

423857

- 06). However, study authors had to abandon the study on about day 200 due to disease of the test organisms that was not related to exposure and the study was classified as unacceptable by HED

. The developmental toxicity study with rat ( MRID 00078796 ) was also classified as unacceptable by HED. Since no acceptable mammalian reproduction or developmental toxicity study was available with the rat for sulfometuron methyl, the developmental toxicity study with the rabbit (Accession No. 78798 ) was used in this risk

assessment ( Table 33 ).

In this study, rabbits were administered doses of 0, 30, 1 00, or 300 mg/kg/day from gestation days (GD) 6

- 18 and examined at GD 29. There were no mortalities and no treatment

- related clinical signs or macroscopic findings. A slight decrease in maternal body weight occurred during the gestation period (GD 6

- 18) but this was judged biologically insignificant. There were no treatment related effects on fetal or maternal endpoints measured, including external, visceral or skeletal malformations, frequency of resorptions, live fetuses, or dead fetuses, or on the

num ber of litters, sex ratio, or post

- implantation loss. The developmental LOAEL was not observed. The developmental NOAEL is 300 mg/kg/day ( highest dose tested). According to the data evaluation record provided by HED, this study is acceptable but does n ot fulfill the guideline requirement for a developmental toxicity study with rabbits because dose levels were not considered high enough to adequately assess developmental toxicity

.

Table 33

. Mammalian Developmental Toxicity of S ulfometuron Methyl

.

Species % ai Test Type Toxicity 1 Affected Endpoints Accession No.

A uthor (year)

Rabbit (New

Zealand White) 100 Developmental NOAEL = 300 mg ai/kg/day (highest test dose) LOAEL > 300 mg ai/kg/day Non e 78798

Serota (1981)



### 3.3.2.6. Terres trial Animal Sublethal Effects , Formulated Product and Degradation Products

No sublethal effects were reported in either the avian dose or dietary acute toxicity studies for birds. However, data on the chronic toxici ty of sulfometuron methyl to birds (and therefore, data on other potential sublethal effects) were not available. For mammals, no clinical signs of toxicity or abnormal behavior were noted in the acute toxicity study (MRID 43089201). No acceptable data o n the chronic toxicity of sulfometuron methyl to mammals were available. Therefore, other potential sublethal effects resulting from chronic exposure could not be evaluated. Based on the developmental toxicity study of sulfometuron methyl to rabbits, no signs of sublethal toxicity were evident (Accession No. 78798).

### 72 Formulated pesticide products may contain a number of other ‘inert’ ingredients that alter the ir toxicity compared to the technical grade active ingredient (e.g., resulting in greater toxicit y). For sulfometuron methyl, data on the oral toxicity of formulated products were available for one species of terrestrial animal (rat; Table 34 ). Results from this study indicate that the formulated product DPX

- T5486

- 87 is pra ctically nontoxic to laboratory rats, with a LD 50 

### of >5,000 mg ai/kg

- bw. No clinical signs of toxicity, weight loss or gross legions were observed in this study. This study satisfied guideline requirements for acute oral toxicity with rats and is conside red acceptable.

Table 34

. Mammalian Acute Toxicity to Sulfometuron Methyl in Formulated

Product: DPX

- T5486

- 87

Species % ai Toxicity Affected Endpoints MRID No. Toxicity Category

Rat (Sprague

- Dawley) 74% LD 50 > 5,000 mg ai/kg

b w (males/females) Survival, weight gain, gross organ pathology 44874103 IV



### Except for saccharin, no toxicity information was available on the other major degradation products of sulfometuron methyl ( e.g., pyrimidine amine, pyrimidine

- ol, sulfonamide). Data on the toxicity of saccharin that met ECOTOX and OPP screening criteria were available for nine studies (Appendix J ). However, further review of these data indicate s they do not contain information on endpoints that are considered ecologically releva nt (i.e., closely related to the assessment endpoints of survival, growth, reproduction and development). These studies mostly focused on saccharin as it relates to human health effects (e.g., carcinogenicity, mutagenicity, organ level endpoints, biochemi cal endpoints). The remaining ecologically

- oriented saccharin studies evaluated the efficacy of saccharin as a deterrent to insect pest damage, fungal infection or its role as an attractant to aquatic life. A list of these studies with rationale for their rejection is provided at the end of “ APPENDIX J: Ecological Effects Studies Rejected by OPP .”

3.3.2.7. Field Studies

Data from field studies of the effects of sulfometuron methyl on terrestrial animals w ere not
available to evaluate effects at organism, population or community levels of biological organization (e.g., population size/growth rate , age

- class structure , or species richness).

3.3.2.8. Terrestrial Plants

Terrestr ial plant Tier 2 seedling emergence and vegetative vigor studies are required for all low dose pesticides (those with the maximum use rate of 0.5 lbs ai/acre or less) and for any pesticide showing a negative response equal to or greater than 25% in Tier 1 studies. Tier 2 terrestrial plant toxicity studies were conducted to establish the toxicity of sulfometuron methyl to non

target terrestrial plants. The recommendations for seedling emergence and vegetative vigor studies are for testing of (1) six specie s of at least four dicotyledonous families, one species of

### 73 which is soybean ( Glycine max ), and the second of which is a root crop, and (2) four species of at least two monocotyledonous families, one of which is corn ( Zea mays ).

For sulfometuron methyl, six dicots (sugar beet, rape, tomato, pea, cucumber and soybean) and four monocots (onion, corn, wheat, sorghum) were tested using the Tier 2 protocols for effects on seedling emergence and vegetative vigor. Tier 1 tests were not conducted since prelimina ry testing indicated all plants would be promoted to Tier 2 testing. Test durations were 14 days and 21 days for the seedling emergence and vegetative vigor studies, respectively. Depending on the species and test, seven to eleven treatments were used wi th application rates ranged from 0.0000017 to 0.5625 lb ai/acre. For this risk assessment, a re

- review and statistical analysis was conducted on the Tier 2 toxicity data from the more sensitive test species in both the seedling emergence and vegetative vi gor tests. All statistical comparisons were made to negative controls (previous analyses in the DER made comparisons to solvent controls even though negative and solvent controls were not significantly different). For calculation of the EC 25 

### and EC 05 

### ,

no nlinear regression was conducted using the methods of Bruce and Versteeg (1992). In situations where the NOAEC was found to be greater than or equal to the EC 25 

### , the EC 05 

### was used for the comparison with threatened and endangered species.

Results for th e most sensitive endpoints and species with monocots and dicots indicate that seedling emergence and vegetative vigor are impacted at exposures well below the maximum application rate of 0.375 lb ai/acre for sulfometuron methyl ( Ta ble 35 ). For seedling emergence,

the EC 25 

### of 1.9 x 10 - 4 

### lb ai/acre for the most sensitive monocot (sorghum) is about a factor of 5 greater than the EC 25 

### of 3.2 x 10 - 5 

### lb ai/acre for the most sensitive dicot (sugar beet ) . The maximum application rate o f 0.375 lb ai/acre exceed s these EC 25 

### values for sorghum and sugar beet by approximately 2,000 and 10,000 times, respectively. For 9 of the 10 test species, a comparison of EC 25 

### values indicates that species sensitivity is within a factor of 20 (based on summary data presented by McKelvey, 1995). This indicates that the most sensitive test species

is not an outlier in terms of its relative sensitivity. The EC 05 

### and NOAEC for the sorghum and sugar beet are 4.3 x 10 - 5 

### and 2.9 x 10 - 5 

### , respectively. A consi stent, declining monotonic

exposure

- response curve was observed for sugar beet, while that for sorghum was monotonic following a n increase in mean shoot height of 24% in the lowest test treatment and 2% in the next lowest treatment relative to the negative control. Because the statistical method of Bruce and Versteeg (1992) uses a pooled response from the non

- monotonic portion of the dose

response curve for calculating EC

x 

### values, the actual mean response associated with the EC 05 

### for sorghum is slightly hi gher than the mean response observed for controls, rendering it a relatively conservative toxicological value.

Results from the vegetative vigor study indicate the most sensitive monocot (corn) and dicot (soybean) are impacted at somewhat lower levels c ompared to the seedling emergence study.

The EC 25 

### values for corn and soybean (shoot dry weight) are 3.7 x 10 - 5 

### and 1.8 x 10 - 5



### , respectively. The maximum application rate for sulfometuron methyl is approximately 10,000 and 20,000 times these EC 25 

### values. Because the NOEC exceeded the EC 25 

### values for both species, the EC 05 

### is used for risk assessment with threatened and endangered species. The EC 05 

### values for corn and soybean are 8.4 x 10 - 6 

### and 9.9 x 10 - 7 

### , respectively. For all 10 test species, a compari son of EC 25 

### values indicates that species sensitivity differences are within a factor of 20 (based on summary data presented by McKelvey, 1995). This indicates that the most sensitive

### 74 test species is not an outlier in terms of its relative sensitivity. A consistent, declining monotonic

exposure

- response curve was observed for corn and soybean in the vegetative vigor test.

Table 35 . Summary of Most Sensitive Tier II Terrestrial Non

- target Plant Seedling Emergence and Vegetative Vigor Toxicity Data for Sulfometuron Methyl.

Most

Sensitive Species EC 25 (lb ai/A) NOAEC/[EC05]* (lb ai/A) Endpoint

Affected MRID No. Author/year Study

Classification

Seedling Emergence

Monocots


### S orghum 1.9 x 10 - 4 4.3 x 10 - 5 (*) shoot height 4 35385

- 01 McKelvey (1995) A cceptable

Dicots 

### sugar beet 3.2 x 10 - 5 2.9 x 10 - 5 shoot dry wt A cceptable
Vegetative Vigor

Monocots 435385

- 01 McKelvey (1995) 

### C orn 3.7 x 10 - 5 9.9 x 10 - 7 (*) shoot dry wt A cceptable

Dicots


### S oybean 1.8 x 10 - 5 8.4 x 10 - 6 (*) shoot dry wt A cceptable

* The NOAEC value is above or equal to the EC 25 or below the lowest concentration, therefore, an EC 05 is used instead.

### 75 

## 4. RISK CHARACTERIZATIO N

Risk characterization provides the final step in the risk assessment process. In this step, exposure and effects characterization are integrated to provide an estimate of risk relative to established levels of concern (LOCs). The results are then interpreted for the risk manager through a risk description and synthesized into an overall conclusion.



## 4.1. Risk Estimation

- Integration of Exposure and Effects

Data

Risk characterization integrates EECs and toxicity estimates and evaluates the like lihood of adverse ecological effects to non

- target species. For sulfometuron methyl, a deterministic approach is used to evaluate the likelihood of adverse ecological effects to non

- target species. In this approach, risk quotients (RQs) are calculate d by dividing estimated environmental

exposures (EECs) by acute and chronic ecotoxicity values for non

- target species.

Risk Quotient ( RQ ) = Exposure Estimate/Toxicity Estimate

RQs are then compared to levels of concern (LOCs). These LOCs are criteria used to indicate potential risk to non

- target organisms and the need to consider regulatory action. LOC

exceedence is interpreted to mean that the labeled use (or proposed use) of the pesticide has the potential to cause adverse effects on non

- target org anisms

. LOCs currently address the following risk presumption categories:

(1) acute

- potential for acute risk to non

- target organisms which may warrant regulatory action in addition to restricted use classification, (2) acute restricted use

– potential for acute risk to non

- target organisms, but may be mitigated through restricted use classification, (3) acute endangered species

– endangered species may be potentially affected by use, (4) chronic risk

– potential for chronic risk may warrant regulatory a ction, endangered species may potentially be affected through chronic exposure, (5) n on

- endangered plant risk

- potential for effects in non

- target (non

- endangered) plants, and (6) endangered plant risk

– potential for effects in endangered plants.

Cu rrently, EFED does not calculate formal risk quotients to assess chronic risk to plants or acute
or chronic risks to non

- target insects . However, these endpoints are evaluated on a case

- by

- case basis as data allow.

Risk presumptions, along with the calc ulation of the c orresponding RQs and LOCs

, are tabulated

below:

### 76 Table 36

. Risk Presumptions for Aquatic Animals

.

Risk Presumption RQ LOC

Acute Risk EEC (1) /LC 50 or EC 50 0.5

Acute Restricted Use EEC/LC 50 or EC 50 0.1

Acute End angered Species EEC/LC 50 or EC 50 0.05

Chronic Risk EEC/NOAEC 1

( 1 ) EEC units in (mg/L or μg/L) in water



### Table 37

. Risk Presumptions for Terrestrial Animals

.

Risk Presumption RQ LOC

Acute Risk EEC (1) /LC 50 or LD 50 /sqft (2) or LD 50 /day (3) 0.5

Acute Restricted Use EEC/LC 50 or LD 50 /sqft or LD 50 /day

(or LD 50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.1

Chronic Risk EEC/NOAEC 1

Acute Endangered Terrestrial Invertebrate EEC ( 4 ) /L D 5 0 (4) 0.05

( 1 ) EEC units are in ppm diet

( 2 ) mg/ sq ft

LD 50 * wt. of bird

(3) mg of toxicant consumed/day

LD 50 * wt. of bird

(4) EEC = ppm in small insects; LD 50 = ug/g bw (ppm)



### Table 38

. Risk Presumptions for Plants

.

Risk Presumption RQ LOC

Terrestrial Plants in Terrestrial and Semi

- Aquatic Areas:

Non

- Endangered Species EEC (1) /EC 25 1

Endangered Species EEC/EC 05 or NOAEC 1

Aquatic Plants:

Non

- Endangered Species EEC (2) /EC 50 1

Endangered S pecies EEC/EC 05 or NOAEC 1

( 1 ) EEC units in lbs ai/acre
( 2 ) EEC units in μg/L or mg/L in water

### 77 4.1.1. Non

- target Aquatic Animals and Plants

A summary of the toxicity values used to derive ris k quotients for aquatic animals and plants is provided in Table 39 below.

Table 39

. Endpoints Used for Estimating Risks of Sulfometuron Methyl to Aquatic Animals and Plants

. (1)

Organism Group Toxicity Units MRID #

Freshwater fish, LC 50 > 148 mg ai/L 435018

- 02

Freshwater invertebrate EC 50 > 150 mg ai/L 435018

- 03

Marine/estuarine fish LC 50 > 45 mg ai/L 416728

- 03

M arine/estuarine invertebrate (mollusk

- oyster) EC 50 > 38 mg ai/L 416728

- 04

Chroni c freshwater fish NOAEC Data gap

Chronic freshw ater invertebrate NOAEC 97 mg ai/L 416728

- 06

Aquatic nonvascular plants EC 50 /NOAEC 4.6 / 0.63 μg ai/L 416801

- 02

Aquatic v ascular plants EC 50 /NOAEC 0.48 / 0.21 μg ai/L 435385

- 03

(1) Details for each study are presented in earlier sections of this document and in APPENDIX H: Ecological Effects Data

Summaries

,



### 4.1.1.1. Fish and Aquatic Invert ebrates

All available LC 50 

### or EC 50 

### values derived from acute toxicity tests on freshwater and marine/estuarine fish and invertebrates are greater than the highest test concentration measured in these studies (>38 to >150 mg ai/L; Table 39 ). Therefore, risks to these taxa are described qualitatively. Compared to these ‘indefinite’ toxicity values, the peak EEC derived from the PRZM/EXAMS scenario yielding the highest exposure ( 31 μg/L) is three orders of magnitude

lower. For bou nding purposes, if one assumes that these indefinite LC 50 

### or EC 50 

### values represent the lower bound of actual (definitive) LC 50 

### or EC 50 

### values from these tests, then the resulting acute RQs would be approximately three orders of magnitude lower than the LOC s for non

endangered aquatic animals. For endangered fish and aquatic invertebrates, the RQs would be approximately two orders of magnitude lower than the LOC of 0.05 . Considering that no mortality was observed at the highest test concentrations from the se acute toxicity tests, the actual RQ values clearly represent conservative estimates of acute risk to these species.

T he lowest available chronic NOAEC in aquatic invertebrates is 97 mg/L (97,000 ug/L). Compared to the highest 21

- d EEC of 2 6 μg/L deriv ed from PRZM/EXAMS modeling, the chronic RQ for freshwater invertebrates would also be several orders of magnitude lower than

the LOC of 1.0.

For chronic toxicity to freshwater fish, no acceptable data were available. In the absence of chronic toxicity data, it is common to apply an extrapolation factor (e.g., acute

- chronic ratio or ACR) to estimate chronic toxicity from acute toxicity test results. However, a valid ACR could

not be determined from the sulfometuron methyl toxicity database because a de finitive LC 50 

### or EC 50 

### was not established for any aquatic animals. Considering data for another sulfonylurea

### 78 herbicide with a similar toxicity profile and the same mode of action (flazasulfuron, PC code:

119011 ), an ACR of 7 can be calculated for rainbow trout:

Rainbow trout LC 50 

### = 115.2 mg ai/L (MRID 4622096 7 ; Sousa 2003 ) Rainbow trout NOAEC = 17 mg ai/L (MRID 46220970; Sousa , 2004 ) ACR = 115.2 / 17 = 7 (rounded)

Thus, applying an ACR of 7 to the LC 50 

### of > 148 for freshwater fish yields an est imated NOAEC of >21 mg/L for sulfometuron methyl. Compared to th e maximum 60

- d average EEC of 20 ug/L derived from the PRZM/EXAMS modeling, the chronic RQ would be at least three orders of magnitude lower than the LOC of 1.0

.

Although chronic studies w ere not available for marine/estuarine fish and invertebrates, there is no evidence to indicate marine or estuarine animals are substantially more sensitive than freshwater animals such that the risk profile would differ markedly from freshwater animals. Furthermore, acute toxicity studies indicate that sulfometuron methyl is not acutely toxic at (or near) toxicity limits for both freshwater and saltwater fish and invertebrates. Considering that the freshwater chronic RQs for fish and invertebrates would be several orders of magnitude lower than the LOCs, it appears highly unlikely that marine and estuarine animals would be at risk from chronic exposures to sulfometuron methyl as determined by PRZM/EXAMS modeling.

Acute and chronic risk to aquatic animal s is further discussed in the Risk Description ( S ection

4.2 ),

4.1.1.2. Aquatic Plants

Risk quotients were derived using the peak EEC of 31 ug/L (determined from the PRZM/EXAMS exposure scenario yielding the highest peak exposure conce ntrations) and EC 50 

### and NOAEC values for vascular and non

- vascular aquatic plants, respectively ( Table 40 )

. For sulfometuron methyl

, RQs exceeded the endangered and non

- endangered LOCs for both vascular

and non

- va scular aquatic plants receiving pesticide runoff/drift , indicating a potential risk to these species.

Table 40

. Summary of Acute Aquatic Plant Risk Quotients for Rights of Way

Uses

.

Scenario Endangered Non

- endangered

Vascular Non

- vascular Vascular Non

- vascular

TX Rights of Way (max rate of 0.375 lbs ai/acre x 1 aerial application/ yr) (a,b) 14 8 (c) 4 9 (c) 6 5 (d) 6.7 (d)

( a ) Based on a peak EEC of 31 ug/L derived from the TX rights of way exposure scenario which yielded the highest EECs. D etail s on scenarios

and PRZM

- EXAMS modeling are provided in Section 3.2.2.2 and APPENDIX C: Ecological Aquatic Exposure Modeling

. (b) For sulfometuron methyl

, endangered plants toxicity threshold (NOAEC) was 0.21μg ai/L for vascular and 0.63 μg ai/L for non

- vascular plants; acute toxicity thresholds (EC 50 ) used for non

- e ndangered plants were 0. .48 and 4.6 μg ai/L for vascular and non

- vascular plants

, respectively.
(c) indicates an exceedence of Endangered Species Level of Concern (LOC); RQ > 1.0.

### 79 (d) indicates an exceedence of non

- target (i.e., non

- e ndangered ) Species Lev el of Concern (LOC); RQ > 1.0.



### 4.1.2. Non

- target Terrestrial Animals

A summary of the toxicity values used to derive risk quotients for terrestrial animals is provided

in Table 41 below.

Table 41

. Endpoints Used for Estimating Risks of Sulfometuron Methyl to

Terrestrial Animals

. Organism Group (a) Toxicity MRID #

Bird LD 50 ( oral dose

- based, mg ai/kg

- bw ) >4,650 245375

Bird LC 50 (dietar y

- based, mg ai/kg

- diet ) >4,600 71414

Mammal LD 50 (oral dose

- based, mg ai/kg

- bw ) >5,000 430892

- 01

Honeybee LD 50 , μg ai/bee >100 416728

- 10

Mammal chronic NOAEL ( dose

- based

, mg ai/kg

- bw/day ) 300 (b) 78798 ( c )

( a ) Details for each study are presented in ear lier sections of this document and in APPENDIX H: Ecological Effects Data

Summaries

. ( c ) Highest dose tested

. ( c ) Accession number

.



### 4.1.2.1. Birds, Acute Risks

T he acute LC 50 

### /LD 50 

### s for birds are greater than the highest concentration/dose tested in each study. Therefore, while precise estimates of RQs are not possible with indefinite (i.e., “greater than”) LC 50 

### /LD 50 

### values, a bounding analysis can be conducted to provide a conservative, upper bound estimate of the RQs ( Table 42 and Table 43 )

.

In this bounding analysis, calculated EECs for various food items from the TREX terrestrial exposure model are compared to dose

- base LD 50 

### values (t reated as definitive values) that have been adjusted for different avian size classes. The highest dose

- based EEC (102 mg ai/kg

- bw/d) is approximately 1/25 th 

### the lowest adjusted dose

- based LD 50 

### (> 2414 mg ai/kg

- bw) thus yielding an upper bound RQ of < 0.0 4. This upper bound RQ is less than the LOCs for acute risk (0.5), acute restricted use (0.2) and acute endangered species (0.1) for terrestrial animals.

Results from diet

- based RQ calculations with birds are similar to those described above for dose

b ased RQs ( Table 43 ) . Specifically, the highest diet

- based 

### EEC (90 mg ai/kg

- diet for short grass) is approximately 1/50 th 

### the avian subacute dietary LC 50 

### of >4600 mg ai/kg

- diet, thus yielding an upper bound RQ of <0.02. This upp er bound RQ is less than the LOCs for acute risk (0.5), acute restricted use (0.2) and acute endangered species (0.1) for terrestrial animals. The potential for acute risk to birds is discussed further in the Risk Description (Section 4.2 )

.

### 80 Table 42

. Upper Bound Kenaga, Acute Avian Dose

- Based Risk
Quotie nts (Bounding Analysis Only)

.

Size Class

(grams) Adjusted

LD 50 (mg ai/kg

- bw) Short Grass (1 )

EEC RQ (2)

20 > 2414 102.5 < 0 .04

100 > 307 4 58. 5 < 0 .02

1000 > 434 2 26. 2 < 0.01

( 1 ) Calculations provided for short grass only because upper bound dose

- based EECs were higher than any other food item

modeled.

( 2 ) RQs derived using unadjusted LD 50 of >4650 mg ai/kg

- bw for mallard and dose

- based EECs (mg ai /kg

- bw) calculated using TREX ver. 1.3.1 with a single application at the maximum allowable label rate (0.375 lb ai/acre/yr). See Section 3.2

and “ APPENDIX H: Ecological Effects Data Summaries ” for details on the model inputs, calculations and output.



### Table 43

. Upper Bound Kenaga, Subacute Dietary

- Based Risk Quotients (Bounding Analysis Only)

. Dietary

- based LC 50 (mg ai/kg

- diet) Short Grass ( 1 )

EEC (2) RQ

> 4600 90.0 < 0 .0 2

( 1 ) Calculations provided for short grass only because upper bound residues were higher than any other food item modeled.
( 2 ) Diet

- based EECs are expressed in units of mg ai/kg

- diet and are calculated using TREX ver. 1.3. 1 based on a single application at the maximum allowable label rate (0.375 lb ai/acre/yr). See Section 3.2 and “ APPENDIX H: Ecological

Effects Data Summaries ” for detai ls on the model inputs, calculations and output. Size class not used for dietary risk quotients.



### 4.1.2.2. Birds, Chronic Risks

As described in Section 3.3, no acceptable chronic toxicity data were available on the effects of sulfometuron methyl on birds. The refore, chronic risks to avian fauna could not be characterized. Uncertainty associated with the lack of chronic toxicity data with avian fauna is further described in the Risk Description section.

4.1.2.3. Mammals, Acute Risks

T he unadjusted, acute LD 50 

### for mam mals is greater than the highest dose tested in the study (> 5000 mg ai/kg for rat; MRID 430892

- 01 )

. Therefore, while a precise estimate of the mammalian acute RQ is not possible with an indefinite (i.e., “greater than”) LD 50 

### value, a bounding analysis

ca n be conducted to provide a conservative, upper bound estimate of the acute, mammalian RQ ( Table 44 )

.

In this bounding analysis, calculated EECs for various food items from the TREX terrestrial exposure model are compared to dose

- base LD 50 

### values (treated as definitive values) that have been adjusted for different mammalian size classes. When the highest EECs (from the short

### 81 grass food item) are compared to the size

- class adjusted LD 50 

### values, the largest upper b ound RQ is < 0.02, which occurs for the 20g mammal size class. This upper bound RQ is less than the LOCs for acute risk (0.5), acute restricted use (0.2) and acute endangered species (0.1) for terrestrial animals. The RQ calculations are detailed in “ APPENDIX F : T

- REX Output ” and acute mammalian risks are further described in the Risk Description (Section 4.2). “

Table 44 . Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients (Bounding Analysis Only)

. (1)

Size Class (grams) Adjusted

LD 50 Short Grass ( 1 )

EEC RQ ( 2 )

15 > 10989 85.8 < 0.01

35 > 8891 59.3 < 0.01

1000 > 3846 13.8 < 0.0 1
(1 ) Calculations provided for short grass only because upper bound dose

- based EECs were higher than any other

food item modeled. (2 ) RQs derived using unad justed LD 50 of >5000 mg ai/kg

- bw and dose

- based EECs (mg ai/kg

- bw) calculated using TREX ver. 1.3.1 with a single application at the maximum allowable label rate (0.375 lb ai/acre/yr). See Section

3.2 and “ APPENDIX H: Ecological Effects Data Summaries ” for details on the model inputs, calculations and

output.



### 4.1.2.4. Mammals, Chronic Risks

To evaluate the chronic risk to mammals, dose

- based and dietary

- based RQs were calculated using the rabbit NOAEL of 300 mg ai/kg

- bw/d from the developmental toxicity study (Accession No. 78798 )

. The rabbit developmental toxicity study was selected for assessing

chronic risks to mammals because an acceptable NOAEL was not available from the 2

- generation chronic rat reproduction study ( that study is considered invalid by HED) or other small mammals (mouse). Because TREX assumes the test NOAEL corresponds to a 350g mammal (rat), calculation of siz e

- class adjusted NOAELs for the rabbit (which averaged 3.9 kg in the study) first involved adjusting the rabbit NOAEL to a 350g mammal adjusted NOAEL using the same equation as TREX. This 350g

, size

- adjusted NOAEL (549 mg ai/kg

- bw/d) was then input to TRE X for the remainder of the chronic mam malian EEC and RQ

.

Neither the chronic, dose

- based risk quotients ( Table 45 ) nor the dietary

- based risk quotients ( Table 46 ) exceed the chronic LOC for all weight cl asses (15 g, 35 g, and 1000g) of mammals consuming short grass, tall grass, broadleaf forage/small insects and seeds. Details of the RQ calculations are provided in (See APPENDIX F : T

- REX Output )

.

Table 45

. Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk
Quotients

.

Size Class

(grams) Adjusted

NOAEL (1)

(mg ai/kg

- bw/d) 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

### 82 15 1206.6 85.8 0.07 39.3 0.03 48. 3 0.04 5.36 <0.0 1 1.19 <0.01

35 976. 3 59.3 0.06 27. 2 0.03 33. 4 0.03 3.71 <0.01 0.82 <0.01

1000 422. 3 13. 8 0.03 6.3 0.01 7.7 0.02 0.86 <0.01 0.19 <0.01

(1) RQs derived for different size classes usin g unadjusted NOAEL of >300 mg ai/kg

- bw/d and dose

- based EECs (mg ai/kg

- bw/d) calculated using TREX ver. 1.3.1 with a single application at the maximum allowable label rate (0.375 lb ai/acre/yr). See Section 3.2 and “ APPENDIX H: Ecological Effects Data Summaries ” for details on the model inputs, calculations and output.



### Table 46 . Upper Bound Kenaga, Chronic Mammalian Dietary

- Based Risk
Quotie nts

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

10980 90.00 0.01 41.25 <0.01 50.63 <0.01 5.63 <0.01

Dietary

- based RQs derived by converting the rabbit NOAEL (>300 mg ai/kg

- bw/d) to a diet

- based NOAEC and comparing with diet

- based EECs (mg ai/kg

- diet) calculated using TREX ver. 1.3.1 at the single maximum allowable label rate (0.375 lb ai/acre/yr). See Section 3.2 and

“ APPENDIX H: Ecological Effects Data Summaries ” f or details on the model inputs, calculations and output. Size class not used for dietary risk quotients



### 4.1.2.5. Non

- Target Terrestrial

- phase Amphibians, Repti les and
Terrestrial Invertebrates

In absence of taxa

- specific data, EFED currently uses birds as surrogate s for terrestrial non

- target terrestrial phase amphibians and reptiles and f ish for aquatic phase amphibians. LOCs were not exceeded for any of the surrogate species; therefore, potential risks to reptiles and amphibians are also presumably lower than the Agency’s concern level.

EFED does not currently estimate risk quotients for terrestrial non

- target invertebrates. However, a label statement is required to protect foraging honeybees when the LD 50 

### is <11 μg/bee. Based on the acute contact toxicity study to honeybees, the LD 50 

### for sulfometuron methyl is >100 μg/bee. This classifies sulfometuron methyl as practically non

- toxic to honeybees on an acute contact exposure basis. For RQ derivation for endangered terrestrial invertebrates, the LD 50 

### for honeybees (>100 ug a.i./bee) is converted to units of μg ai/g (of bee) by multiplying by 1 bee/0.128 g, thereby resulting in an LD 50 

### of >780 μg ai/g. T his LD 50 

### value is then compared to the EEC of 50.6 ug/g for small insects/broadleaf plants ( Table 17 ). The resulting RQ (EEC/LD 50 

### ) is <0.06, which is at or below the LOC for endangered terrestrial invertebrates (0.05). Therefore, the risk of direct adverse effects to terrestrial invertebrates is considered low; however, due to the potential risk identified to plants, the potential for indirect effects to terrestrial invertebrates from sulfometuron methyl use cannot be discounted.

Additional discussion of potential r isks to these taxa is qualitatively discussed in the Risk Description portion of this document ( Section 4.2 ).

### 83 4.1.3. Non

- target Terrestrial Plants

A summary of the toxicity values used to deriv e risk quotients for terrestrial plants is provided in

Table 47 below.

Table 47

. Summary of Selected Endpoints from Terrestrial Plant Toxicity Studies

of Sulfometuron Methyl

Organism Group Toxicity

(Lb s A.I./Acre) M RID #

Terrestrial monocots emergence, EC 25 , lbs ai/acre

EC 05 or NOAEC, lbs ai/acre EC 25 = 1.9 x 10
- 4

EC 05 = 4.3 x 10
- 5 435385

- 01

Terrestrial dicots emergence, EC 25 , lbs ai/acre

EC 05 or NOAEC, lbs ai/acre EC 25 = 3.2 x 10
- 5

NOAEC = 2.9 x 10
- 5 435385

- 01

Terrestrial monocots vegetative vigor, EC 25 , lbs ai/acre

EC 05 or NOAEC, lbs ai/acre EC 25 = 3.7 x 10
- 5

EC 05 = 8.4 x 10
- 6 435385

- 01

Terrestrial dicots vegetative vigor, EC 25 , lbs ai/acre

EC 05 or NOAEC, lbs ai/acre EC 25 = 1.8 x 10
- 5

EC 05 = 9.9 x 10
- 7 435385

- 01

a Details for each study are presented in earlier sections of this document and in “ APPENDIX H: Ecological Effects Data Summaries ”

.



### 4.1.3.1. Non

- Endangered and Endangered Plant Risks

Table 48 p resents terrestrial plant RQs for sulfometuron methyl based on aerial and ground spray applications. These RQs were derived using TerrPlant (ver 1.2.2) using a single application rate

at the annual maxim um of 0.375 lb ai/A. TerrPlant is a Tier 1 model that estimates pesticide aerial drift and runoff to dry and semi

- aquatic adjacent areas. Results indicate that t he LOC s are widely exceeded for non

- endangered and endangered monocots and dicots located in adjacent dry areas and in semi

- aquatic areas as the result of receiving a combination of runoff and spray drift from ground and aerial applications. In addition, the LOCs were exceeded for terrestrial plants receiving spray drift alone from ground and aeri al application. These risks will be discussed in detail in the AgDrift spray drift analysis in the Risk Description ( Section 4.2 )

. However, TerrPlant modeling results are based on the assumption of a single application, risk

qu otients for non

- target terrestrial plants may be underestimated. Bold indicates an LOC

exceedence in Table 48

.

Table 48

. RQ Values For Plants In Dry And Semi

- Aquatic Areas Exposed To Sulfometuron Methyl Through Runoff And/Or Spray Drift

.

Plant Type Application Method Terrestrial Adjacent

Areas Semi

- Aquatic Adjacent

Areas Spray Drift

Non

- endangered Plant RQs a,b,d

Monocot ground spray 118 1007 101

Dicot ground spray 703 5977 208

Monocot Aerial 197 1086 507

Dicot Aerial 1172 6445 1042

Endangered Plant RQs a,c,d

### 84 Monocot ground spray 523 4448 446

Dicot ground spray 776 6595 3788

Monocot Aerial 872 4797 2232

Dicot Aerial 1293 7112 18939

a De tailed calculations for RQs and TerrPlant (ver 1.2.2) inp ut and output are provided in “ APPENDIX D: Terrplant Spreadsheet

. ”

b Non

- endangered toxicity thresholds (EC 25 ) a re 1.9 x 10
- 4 (seedling emergence, monocot), 3.2 x 10

- 5 (seedling emergence, dicot),

3.7 x 10
- 5 (veg etative vigor, monocot), 1.8 x 10

- 5 (vegetative vigor, dicot) lb ai/A

.

c Endangered toxicity thresholds (NOAEC of EC 05 ) a re 4.3 x 10
- 5 (seedling emergence, monocot), 2.9 x 10

- 5 (seedling emergence, dicot), 8.4 x 10

- 6 (vegetative vigor, monocot), 9.9 x 10

- 7 (vegetative vigor, dicot) lb ai/A

. d Bold RQ values exceed the Non

- Endangered Species LOC and Endangered Species LOC ( RQ >1.0 )

.



### 4.1.4. Use of Contaminated Irrigation Waters

The potential risk to plants when exposed to irrigation water contaminated with sulfom eturon methyl is presented in the form of RQs in Table 49

. These RQs are derived using EECs of 0.33 μg/L (ground water) and 31 μg/L (surface water). The EEC for ground water was calculated using the Tier 1 SCIGROW model ( Table 16 ) while that for surface water was calculated using PRZM/EXAMS for the scenario yielding the highest EECs ( Table 15 ). For semi

- aquatic and terrestrial areas adjacent to irrigation fields, EECs in lb ai/acre were calculated assuming 1% of the irrigation water drifts into adjacent wetlands. It was further assumed that no runoff of irrigation water occurs. Toxicity endpoints were taken from the vegetative vigor study because it

was assumed th at non

- target plants are exposed to sulfometuron methyl directly through spray drift from irrigation water. Details of the calculatio n of the irrigation EECs are provided in

APPENDIX G: Modeling of Terrestrial plant Exposure from Contaminated irrigation Water ).

Based on this screening analysis, results suggest that sulfometuron methyl levels in irrigation water from ground water sources would not exceed non

- target or endangered species LOCs (i.e, RQs < 1.0). However, RQs based on sulfometuron methyl in irrigation water derived from

surface water sources exceed the LOCs for both non

- target and endangered species (3. 9 and 71

, respectively), thus indicating a potential risk to plants adjacent to areas irrigated with surface

water sources.

Table 49

. Risk Quotients for Non

- target and Endangered Plants, Resulting From Exposure to Sulfometuron Methyl in Irrigation Water

Location Ground water and

Surface Water EEC: 1, 2

(lbs ai/A) Risk Quotients:

Ground wat er (GW) and Surface Water (SW) Irrigation

Non

- target plants 3

(EEC/EC25) Endangered plants 3

(EEC/NOAEC)

Semi

- aquatic and terrestrial areas adjacent to irrigated

fields Ground water: 7.5 x 10

- 7

Surface water: 6.1 x 10

- 5 GW: 0.04

SW: 3. 9 GW: 0.76

SW: 71

1 Estimated EEC assumes 1 inch of irrigation water is applied to the target field, 1% drift of irrigated water containing sulfo meturon methyl, and no runoff of irrigated water. See Appendix G for details on irrigation exposure calculations.

2 E ECs based on sulfometuron methyl concentrations of 0.33 ug/L in ground water and 31 ug/L in surface water

3 Based on non

- target plant EC25 of 1.8 x 10

- 5 lb ai/A and endangered plant NOAEC of 9.9 x 10

- 7 (MRID 435385

- 01) for the most sensitive vegetative vig or endpoint. Bold RQ indicates exceedence of LOC of 1.0 (i.e., RQ > 1)

### 85 

## 4.2. RISK DESCRIPTION

4.2.1. Risk to Aquatic Animals and Plants

In the conceptual model, spray drift and surface runoff/leaching to adjacent bodies of water were predicted as the most likely sources of exposure of sulfometuron methyl to non

- target aquatic animals and plants. Risks to aquatic organisms (i.e. fish, invertebrates, and plants) were assessed based on modeled estimated environmental concentrations (EECs) and available toxicity dat a. Aquatic EECs for the ecological exposure to sulfometuron methyl were estimated using PRZM

EXAMS employing the standard ecological water body (Section 3.2.2.2 ; Table 1 3 ).

The risk hypothesis stated that the use of sulfometuron methyl has the potential to cause adverse effects to aquatic animals and plants. This assessment confirms this hypothesis. Risk s of direct effects to aquatic vascular and nonvascular plants ar e above the Agency’s LOC s . However, t he

assessment refutes th e risk hypothesis regarding direct effects to aquatic animals

, suggest ing that

direct effects to aquatic animals are unlikely. Although risk from direct toxicity to aquatic

animals is not indic ated in this screening level assessment, the dependence of aquatic animals on primary producers (plants) results in the potential for indirect effects to aquatic animals.

4.2.1.1. Fish and Aquatic Invertebrates

The submitted acute toxicity data for aquatic spec ies indicate that sulfometuron methyl is practically non

- toxic to fish and invertebrates with LC 50 

### and EC 50 

### values > 38 to >150 mg ai/L, respectively. A comparison of the PRZM/EXAMS peak EEC of sulfometuron methyl in surface

water of 31 ug/L to toxicity va lues for fish and invertebrates indicates that the se indefinite (i.e., ‘greater than) acute toxicity values are three orders of magnitude above the highest peak EEC. A bounding analysis indicates that even if these indefinite LC 50 

### and EC 50 

### values are inte rpreted as the lower bounds for acute toxicity (a conservative assumption since no mortality occurred in these test concentrations), the resulting acute RQs would still be at least two orders of magnitude

below the LOCs for non

- endangered and endangered aq uatic animals. This risk finding is consistent with those from other ecological risk assessments with sulfonylurea herbicides (e.g., florasulam, flazasulfuron). While it was noted in the Analysis Section ( 3.3 ) that uncertainty exists in the actual exposure concentration derived from the estuarine/marine acute toxicity tests, this uncertainty is not judged to be large enough to impact the risk conclusions, given the large difference between EECs and toxicity lev els.

Therefore, it is concluded that acute risk to aquatic animals from direct effects of sulfometuron methyl is expected to be minimal.

Similarly, chronic risk quotients are all less than the LOC of 1.0 for the modeled uses. For freshwater aquatic in vertebrates and fish, the PRZM/EXAMS 21

- day EEC (2 6 ug/L) and 60

- d EEC ( 20 ug/L) are also three orders of magnitude below the chronic NOAEC of 97 mg/L and >21 mg/L, respectively. As noted in the Analysis Section ( 3.3 ), the chronic NOAEC for fish had to be estimated using an ACR of 7 derived from another chemical (flazasulfuron) with a similar toxicity profile and mode of action. Clearly, there is uncertainty associated with extrapolation of

### 86 an ACR across chemic als, as ACRs can vary by chemical, species, test designs, and other factors. In a recent analysis , Raimondo et al. (2007) evaluated the variability in ACRs derived from multiple sources, including EFED’s Pesticide Ecotoxicity database. Raimondo et al. (2 007) report a 90 th 

### percentile ACR of 80 across all chemicals, which if applied to the freshwater fish

LC 50 

### o f > 148 mg/L, would yield an estimated N OAEC of > 2 mg/L. This value is still 100

- fold higher than the chronic 60

- d EEC of 20 ug/L. This 90 th 

### perc entile ACR reflects pesticides with modes of action that differ from sulfometuron methyl and therefore may not reflect the 90 th


### percentile ACR within the sulfonylurea class of herbicides. However, for the purposes of evaluating uncertainty in acute

- to

- chr onic toxicity extrapolations, it is considered a reasonable approximation of a “high end” ACR.

The potential for chronic risks to fish was further evaluated by comparing the 60

- d (chronic) EEC for freshwater fish with available chronic toxicity values ( NOAECs) for other sulfonylurea herbicides ( Figure 3 ). Results indicate that chronic toxicity of other sulfonylurea herbicides

occurs at concentrations two to three orders of magnitude greater than the chronic EEC of 0.020 mg/L. Therefore, based on the use of a conservative “high end” ACR and comparison with toxicity information for other sulfonylurea herbicides, the potential for chronic risk to aquatic

animals from direct effects of sulfometuron methyl appears un likely.

Figure 3 . Chronic Toxicity of Sulfonylurea Herbicides to Freshwater Fish

0.01

0.1

1 10 100 1000

Foramsulfuron (FM) Imazapyr (FM) Bensulfuron Methyl (FM) Prosulfuron (FM) Sulfosulfuron (RT) Chlorsulfuron (RT) Halosulfuron methyl (RT) Metsulfuron methyl (RT)NOAEC (ppm) 60-d EEC = 0.020 ppm

Source: EPA/OPP Ecotoxicity Database, core studies only, Oct., 2007; FM = fathead minnow ; RT = rainbow

### 87 Although no chronic studies in saltwater fish or invertebrates have been submitted to the Agency, the acute studies do not indicate that saltwater species are e xpected to be more sensitive than freshwater species. Given the low magnitude of the freshwater animal risk quotients, submission of chronic studies in saltwater species would not likely affect conclusions of this

assessment.

An ECOTOX literature searc h found no acceptable or supplemental studies on the acute toxicity of technical grade sulfometuron methyl to fish or invertebrates. Results from a supplemental study of microcrustaceans using the formulated product, Oust, indicates that sulfometuron

meth yl is practically nontoxic to these aquatic invertebrate crustaceans . T herefore, toxicity findings of the formulated product (Oust ® 

### ) are consistent with those using the technical grade active ingredient with Daphnia magna (MRID 435018

- 03)

.

4.2.1.2. Non

- target Aqu atic

- phase Amphibians

EFED currently uses surrogate data (fish) to estimate potential risks to non

- target aquatic phase amphibians. Risks to fish species were discussed above and do not indicate significant risk to these organisms.

One study of the effe ct of sulfometuron methyl on an aquatic

- phase amphibian was found was found that met OPP/ECOTOX screening criteria ( Table 50 ). In this study, Fort et al. (1999) conducted three separate tests of sulfometuron methy l exposure to the African clawed frog, Xenopus laevis : (1) a 4

- day frog embryo teratogenesis assay (FETAX ) to evaluate embryo mortality/ malformations; (2) a 14

- d test to evaluate effects on tail resorption, and (3) a 30

- d exposure to evaluate effects on l imb development. Both analytically impure (85% ai) and purified (99.5% ai) sulfometuron methyl exposures were evaluated in the study, but due to the confounding influence of impurities on sulfometuron methyl toxicity, results from only the purified (99.5% ai) sulfometuron methyl are used here.

In the FETAX assay, 2 replicates of 20 mid

- blastula frog embryos (stage 8) were exposed to 11 nominal test concentrations of sulfometuron methyl ranging from 0.001 to 2 4.9 mg ai/L for 96

- h. Sulfometuron methyl sto ck solutions were prepared using a DMSO carrier and verified analytically (analytical results not reported). Both a negative and solvent control were included. Test procedures generally conformed to ASTM recommendations for the FETAX assay (ASTM, 1996). Results indicate no statistically significant effect of sulfometuron methyl on embryo survival or percent malformations up to (and including) the highest test concentration (2 4.9 mg ai /L). Solvent controls were not significantly different from negative c ontrols.

Similar results were found in the 30

- d study, whereby no statistically significant effect of sulfometuron methyl exposure was found on limb development (% malformations) up through

2 4.9 mg ai /L. Results from the 14

- d tail resorption study indica te a significant reduction in tail resorption at 9.95 and 2 4.9 mg ai/L beginning at development stage 64 through 66 (test termination). No significant reduction occurred at or below 1 mg ai/L.

This study is classified as supplemental primarily because ex posure concentrations were not measured during the test. Although the authors report that sulfometuron methyl was ‘stable’

### 88 over the 24 to 96

- h renewal cycles used in the studies, no analytical chemistry results were provided. Furthermore, randomization o f study organisms and replicates was not indicated (an ASTM requirement). Collection and testing of embryos by separate clutches (an ASTM recommendation) was not apparent in the study. Finally, the final concentrations of carrier

solvent in the various tr eatments was not reported ( solvent concentrations were only reported for

the stock solutions).

Table 50 . Toxicity of sulfometuron methyl to the African clawed frog from a study by Fort et al. (1999).

Species Test

Chemical Expo sure Duration Endpoint (Effect) Effect

Level (mg ai/L) Study

Classification Ref.

Xenopus

laevis sulfometuron methyl (99.5% ai) 96

- h LC 50 (% mortality) NOAEC (% malformations) > 2 4.9

2 4.9 (a) Supplemental Fort et al. (1999)

14

- d NOAEC (tail resorp tion) LOAEC (tail resporption) 0.995

9.95

30

- d NOAEC (limb deformation) 2 4.9 (a)

(a) Highest tested dose, LOAEL not achieved in study.



### Although results from the Fort et al (1999) study are not being used quantitatively in this risk assessment, the y suggest that acute toxicity to Xenopus larvae occurs at levels > 1000 times the

maximum EEC of 31 ug/L derived from the PRZM/EXAMS model. The lowest NOAEC from this study (1.0 mg/L) is approximately 45 times higher than the maximum 21

- d EEC of 2 6 ug/L. Therefore, based on conclusions for fish discussed previously and supplemental information from Fort et al (1999), risk to aquatic phase amphibians is also expected to be lower than the Agency’s concern level

.

4.2.1.3. Aquatic Plants

Toxicity studies indicate that sulfometuron methyl is classified as highly toxic to aquatic plants, and the RQ values ( 6 5

- 1 48 for vascular plants; 6.7

- 4 9 for nonvascular plants) indicates the potential risk to aquatic vascular and nonvascular p lants is above the Agency’s concern level.

T he freshwater vascular plant (duckweed) is the most sensitive aquatic plant species (14

- d EC 50 

### and NOAEC are 0.48 and 0.21 μg/L, respectively) followed by the green algae ( EC 50 

### is 4.6 μg ai /L and the NOAEC is 0 .63 ug ai/L). Sulfometuron methyl was much less toxic to diatoms (>370 and >410 mg/L), and potential risks to this taxonomic group do not exceed the Agency’s

concern level.

In the duckweed study described previously (MRID 435385

- 03 ), recovery from the 14

- d sulfometuron methyl exposures was assessed at the end of the study by exposing organisms to untreated medium for an additional 14 days. Effects were expressed as percent inhibition of

frond counts and biomass. The results are as follows:

### 89 14

- d Recovery 14

- d Recovery:

14

- d Exposure Conc. Frond Count Inhibition Biomass Inhibition

1.045 ppb 41.1% 38.3% 0.590 ppb 11.8% 10.8% 0.323 ppb 0.6%

- 1.0%

Therefore, the study authors concluded that sulfometuron me thyl was phytotoxic to duckweed at

concentrations of > 0.590 ppb and phytostatic at 0.323 ppb. These data suggest that the effects of sulfometuron methyl to aquatic vascular plants may be reversible following 14

- d exposures at selected concentrations (0.3 23 ppb and below). To evaluate the potential for duckweed (and by extension, other vascular plants) to recover from sulfometuron methyl exposures predicted using PRZM/EXAMS modeling, the predicted long

- term exposures to sulfometuron methyl (e.g., 90

- d

ave rage concentration) was compared to available toxicity information. Results indicate that the

90

- d average concentration (1 6 ug/L; Table 15 ) derived from the exposure scenario yielding the highest exposure concentr ations still exceed s the 14

- d EC 50 

### (0.48 ug/L) by a factor of 3 3 and the

14

- d phytotoxic concentration (0.59 ppb) by a factor of 27

. Therefore, the ability of duckweed and other vascular aquatic plants to recover from predicted long

- term exposure concentr ations of sulfometuron methyl in adjacent, static aquatic systems appears unlikely. The sensitivity of RQ estimates for aquatic vascular and nonvascular plants to different assumptions regarding application rates and timing of application is discussed lat er in S ection 4.3

.

Byl et al. (1994) conducted a laboratory study on the effect of sulfometuron methyl on the aquatic vascular plant, Hydrilla verticillata. In this study, Byl et al. (1994) exposed plants to aqueous soluti ons ranging from 0.001 to 1.0 mg/L sulfometuron methyl (as Oust) in three replicate chambers per treatment for 5 days. The % ai was not reported nor is it clear whether nominal concentrations reflect adjustment for % ai. A significant decrease in combine d shoot

and root length was observed at or above 0.01 mg/L ( approximating 30% of the controls )

. Although not conclusive, r esults from Byl et al. suggest that the combined root and shoot length response of Hydrilla is less sensitive to 5

- d exposure to the formulated product (Oust) compared

to the 14

- d exposure to TGAI for duckweed (NOAEC = 0.21 ug ai/L), even if nominal concentrations are adjusted downward to reflect the typical 75% ai found in Oust. However, the relative toxicity of TGAI and formulated pr oduct can not be determined conclusively from comparison of these two studies because study protocols differed substantially (e.g., exposure duration, measurement endpoints).

4.2.1.4. Aquatic Toxicity of Sulfometuron Methyl Degradates

As discussed earlier in Se ction 3.3.1.7 , no acceptable or supplemental studies were available on the toxicity of the major sulfometuron methyl degrad ates to aquatic organisms. To characterize the potential toxicity of the major degradates of sulfometur on methyl, predicted toxicity values were determined from EPA’s ECOSAR model (v. 0.99h). Note that these QSAR results should not, by OPP policy, be used directly for risk management decisions. This model is based on quantitative structure activity relatio nships (QSAR) for chemical effects on fish , daphnids, and green algae. Table 51 displays the results of the ECOSAR model predictions for five major sulfometuron methyl degradates.

### 90 Table 51

. ECOSAR

- pre dicted toxicity values for major degradates of sulfometuron methyl.

Degradate Name ECOSAR Class Organism Toxicity Endpoint Toxicity Value (mg/L)

2

- Hydroxy, 4,6

- dimethyl pyrimidine Phenols Fish 96

- h LC 50 90

- d Chronic Value 49

0.31 Daphnid 48

- h LC 50 21

- d Chronic Value 13

5.3 Green Algae 96

- h EC 50 257

2

- (Aminosulfonyl) benzoic acid Neutral organic

acids Fish 96

- h LC 50 30

- d Chronic Value 137,000* 12,600 Daphnid 48

- h LC 50 16

- d EC 50 128,000* 2,620 Green Algae 96

- h EC 50 70,676

Saccharin Thiazolino ne (iso

- ) Fish 96

- h LC 50 Chronic Value** 1.9

0.14 Daphnid 48

- h LC 50 Chronic Value** 1.6

0.057 Green Algae 96

- h EC 50 0.41

2

- (Aminosulfonyl) benzoic acid, methyl ester Esters Fish 96

- h LC 50 Chronic Value** 152

136 Daphnid 48

- h LC 50 2,350

Green A lgae 96

- h EC 50 Chronic Value** 11.6

8.7

2

- Pyrimidinamine, 4,6

- dimethyl Aromatic amines Fish 96

- h LC 50 Chronic Value** 214

0.93 Daphnid 48

- h LC 50 Chronic Value** 1.6

0.042 Green Algae Chronic Value** 12.9
* predicted toxicity value may exceed compo und’s aqueous solubility ** duration associated with the reported chronic value was not reported by the ECOSAR program The peak, 21

- d, and 90

- d EECs predicted for the parent chemical, sulfometuron methyl are: 0.031, 0.026, and 0.016 mg/L,

respectively ( 

### Table 15 )



### Toxicity predictions from the ECOSAR model ranged widely across the five degradates, likely due in part to the differences in chemical structure and ECOSAR class used for the predictions (e.g., phenols, neutral organic acids, thialozinone, esters and aromatic amines).

Predicted toxicity and risk characterization for 2

- (aminosulfonyl) benzoic acid Of the five degradates evalu ated, 2

- (aminosulfonyl) benzoic acid was predicted to be the least toxic, wit h toxicity predictions for all aquatic species tested ranging from 2,600 to 137,000 mg/L. Predicted EECs were not modeled for the any of the degradates due to lack of appropriate data on the environmental fate of these compounds. However, if one assumes the EECs for the degradates are similar that of the parent compound (sulfometuron methyl), then the toxicity value

for 2

- ( a minosulfonyl) benzoic acid appears at least 5 orders of magnitude greater than the EEC for sulfometuron methyl. While this assumptio n may have uncertainty due to the potential differential environmental fate characteristics of sulfometuron methyl and 2

- ( a minosulfonyl)

benzoic acid , it appears highly unlikely that such differences would span the 5 order of

### 91 magnitude range between EECs a nd predicted toxicity values for 2

- ( a minosulfonyl) benzoic

acid , thus suggesting that the potential ecological risk to fish, daphnids and green algae

associated with 2

- ( a minosulfonyl) benzoic acid would be highly unlikely.

Predicted toxicity and risk ch aracterization for the other degradates

Effects on Fish. With the remaining four degradates ( 2

- h ydroxy, 4,6

- dimethyl pyrimidine

,

s accharin

, 2

- ( a minosulfonyl) benzoic acid, methyl ester , and 2

- p yrimidinamine, 4,6

- dimethyl ), the predicted acute and chronic toxicity values for fish ranged from 1.9

- 214 mg/L and 0.14

- 136 mg/L, respectively ( Table 51 ). Except for saccharin, these predicted acute toxicity values for fish were comparable to those observed for sulfometuron methyl (>150 mg ai/L). The predicted acute toxicity of saccharin to fish was at least two orders of magnitude lower than that observed sulfometuron methyl. However, when compared to the peak predicted EEC for sulfometuron methyl (0.031 mg/L), the predicte d acute toxicity of the degradates to fish is still at least two orders of magnitude greater (1.9

- 214 mg/L). The lowest predicted chronic toxicity value for fish (0.14 mg/L for saccharin) was about an order of magnitude greater than the predicted 90

- d EEC for sulfometuron methyl (0.016 mg/L). Given the relatively long degradation half lives used to predict EECs for sulfometuron methyl (e.g., several months or longer, Table 13 ), it also appears unlikely that these degradates would reach co ncentrations that would exceed those of sulfometuron methyl by 1

- 2 orders of magnitude (although it is possible that exposure on a molar basis to the most persistent degradates could be somewhat higher than to parent).

Effects on daphnids. For dap hnids, the acute and chronic toxicity values predicted from ECOSAR ranged from 1.6

- 2,350 mg/L and 0.042

- 5.3 mg/L, respectively, for the remaining four degradates: 2

- h ydroxy, 4,6

- dimethyl pyrimidine , s accharin

, 2

- ( a minosulfonyl) benzoic acid, methyl ester

, and 2

- p yrimidinamine, 4,6

- dimethyl ( Table 51 ). When compared to the peek EEC of 0.031 mg/L for sulfometuron methyl, the ECOSAR

- predicted acute toxicity of the degradates was at least two orders of magnitude great er (1.6

- 2,350 mg/L). However, for two degradates (saccharin and 2

- p yrimidinamine, 4,6

- dimethyl ), the ECOSAR

- predicted chronic toxicity (0.052 and 0.042 mg/L, respectively) are relatively close to the 21

- d EEC of sulfometuron methyl (0.026 mg/L). Thus, if the EECs for these degradates are comparable to the parent compound (sulfometuron methyl) and the toxicity predictions from ECOSAR are accurate, chronic toxicity of these two degradates to daphnia would be just a factor of two greater than the degradate E ECs

.

Effects on green algae. For green algae, the ECOSAR

- predicted acute and chronic toxicity values for the degradates (0.41

- 257 mg/L ; ( Table 51 ) are much greater than those of sulfometuron methyl (0.0046 and 0 .00063 for acute and chronic toxicity, respectively. This finding is expected given the mode of action of the degradates likely differ from sulfometuron methyl, which is specific to ALS inhibition in plants. The most sensitive of these toxicity values ( 0.41 mg/L for saccharin) is about an order of magnitude greater than the peak EEC of 0.031 mg/L for sulfometuron methyl. This implies the potential risks from sulfometuron methyl to aquatic plants (green algae) are much more of a concern compared to its d egradates. However, the phytotoxicity of saccharin may not be discounted entirely, especially if there is an underestimation of saccharin toxicity by ECOSAR and/or a higher level of exposure to saccharin due to (possibly) greater environmental persistence

.

### 92 Although the above comparisons are subject to considerable uncertainty in both the toxicity estimates (ECOSAR) and EECs (assumed to be similar to those for sulfometuron methyl), they do suggest that the toxicity of the degradates is like ly not a domina nt concern, with the possible exception of chronic toxicity to freshwater invertebrates (daphnia) and acute toxicity to algae.

4.2.2. Risk to Terrestrial Animals

In the conceptual model, direct deposition, spray drift, root uptake, sediment and water runoff

wa ter, wind erosion of soil particles , and volatilization/inhalation are identified as the most likely exposure routes for sulfometuron methyl exposure to non

- target terrestrial organisms. Risks to terrestrial animals and plants (i.e. birds, terrestrial

- pha se amphibians, reptiles, mammals, and plants) were assessed based on modeled EECs and available toxicity data. As part of th is screening terrestrial risk assessment, exposure concentrations of sulfometuron methyl to non

target terrestrial plants and anima ls were modeled according to maximum labeled application

rates. For terrestrial birds , terrestrial

- phase amphibians, reptiles and mammals, estimates of upper bound levels of sulfometuron methyl residues on various food items, which may be

contacted or con sumed by wildlife, were determined using the Fletcher nomogram followed by a

first order decline model TREX 1. 3.1 . Likewise, the TerrPlant 1.2.2 model was used to estimate

exposure to non

- target plants and the AgDRIFT 2.0.1 model provided further refineme nt of spray drift dispersion and deposition to terrestrial plants located in proximity to treated fields. Note that AgDRIFT offers the ability to examine the variation in the amount of spray drift with application practices and conditions whereas TerrPlant does not (fixed values are used). Since spray drift is a dominant contributor to off

- site exposure to terrestrial animals, the AgDRIFT predicted exposures, depending on the input assumptions, may be higher than those estimated

with TerrPlant.

The risk hy pothesis stated that the use of sulfometuron methyl has the potential to cause adverse effects to terrestrial animals and plants. This risk hypothesis is confirmed for terrestrial plants,

and also for adverse effects to non

- target terrestrial animals via indirect effects resulting from potential effects to plants

. However, t he assessment refutes th e risk hypothesis regarding direct effects to animals and suggests that direct effects to terrestrial animals are unlikely.

4.2.2.1. Birds

Sulfometuron methyl is cat egorized as practically non toxic to both waterfowl (mallard duck) on an acute oral basis (LD 50 

### > 4,650 mg/kg

- bw) and practically nontoxic to both upland game birds

and waterfowl by the subacute dietary route (L C 50 

### >5, 620 mg/kg

- diet and > 4,600 mg/kg

- diet,

r espectively) . Since the LD 50 

### and LC 50 

### values are greater than the highest dose tested in the

studies , with no effects occurring at any dose

, a bounding analysis was conducted to evaluate potential effects associated with acute oral and subacute dietary exp osure to sulfometuron methyl ( Section 4.1 ; Table 42 and Table 43 ). This bounding analysis compared size class ad just ed

‘indefi nite’ LD 50 

### values (i.e., ‘greater than’ values ) based on a bird’s weight to predicted doses on food residues (EEC equivalent dose) following a single ground application of sulfometuron methyl at 0. 375 lb ai/A. Based on this analysis, predicted RQs were all < 0.04 or lower, despite

### 93 the conservative assumption that the ‘indefinite’ LC 50 

### and LD 50 

### values (at which no mortality was observed in the test) represent definitive LC 50 

### and LD 50 

### values (w h ere 50% mortality occurred). Therefore, risk to birds from acute oral and subacute dietary exposure to sulfometuron methyl is judged to be highly unlikely.

No data were available on the effects of sulfometuron methyl to avian fauna from chronic exposures. Therefore, risks to birds from chronic exposure to sulfometuron methyl could not be directly quantified in this risk assessment. A qualitative assessment is conducted here based on

chronic avian toxicity data obtained for 12 studies from 9 other sulfonylurea herbicides with the

same mode of action (inhibition of acet olactate synthase ; Figure 4 ). These data were obtained from EFED’s Ecotoxicity database using a cross reference with another EFED “Active Ingredient” database that links active ingredients with mode of action. Although these 12 sulfonylurea herbicides likely do not represent the entire universe of sulfonylureas with chronic avian toxicity data, they are considered to provide a representative sample from which to qualitatively evaluate the uncertainty associated with lack of chron ic avian toxicity data for sulfometuron methyl.

Figure 4 . Chronic Avian Toxicity of Sulfonylurea Herbicides

Results from Figure 4 indicate that out of the 12 chronic avian NOAECs exam ined for sulfonylurea herbicides

, two occurred below the peek EEC of 90 mg ai/kg

- diet calculated for short grass ( Table 17 ). These two NOAECs were 30 mg ai/kg

- diet for t ribenuron methyl (MRID

43594201 ) and 28 mg ai/kg

- diet for pr osulfuron (MRID 42949701 ). The LOAELs from these two studies (180 and 100 ppm, respectively) are above the 90 mg ai/kg

- diet peek EEC. Thus, out of the 9 sulfonylureas evaluated, the peak EEC would exceed the LOC for 2 herbicides (or 12% of the chemicals). This finding is consistent with the generally low toxicity sulfonylurea

herbicides terrestrial animals

. Thus, while considerable uncertainty exists in extrapolating chronic NOAELs across chemicals even within the same mode of action, these results sugges t that chronic toxicity to avian fauna is not likely to be a dominant concern in this risk assessment, 1 10 100 1000 10000

Tribenuron methyl (BQ) Chlorimuron Ethyl (BQ) Triasulfuron (BQ) Thifensulfuron-methyl (BQ) Prosulfuron (MD) Tribenuron methyl (MD) Metsulfuron methyl (MD) Sulfosulfuron (MD) Primisulfuron-methyl (MD) Chlorsulfuron (MD) Triasulfuron (MD) Thifensulfuron-methyl (MD)

Soruce: OPP Ecotoxicity Database, core studies only (Oct, 2007); BQ = bobwhite quail, MD =

mallard duck Peek EEC = 90 mg/kg-diet

### 94 although it cannot be discounted entirely since LOCs would be exceeded for 2 of the 9 herbicides

evaluated.

4.2.2.2. Mammals

As observed for avian fauna, sulfo meturon methyl is classified as practically nontoxic on an acute basis to mammals. As described in Section 4.1, a bounding analysis compar ed predicted

EECs to indefinite LD 50 

### values (adjusted for different size classes) for the purposes of estimating

the upper bound of acute toxicity risk. The highest EEC for mammals is 85.8 mg/kg

- bw for short grass consumed by a 15 g mammal. The adjusted LD 50 

### for 15 g mammals would be 10

, 989 mg/kg bw. There is an approximately 120

- fold difference between these two val ues. Since the acute RQs for all weight classes of mammals consuming all feed types are < 0.01 and less than the Agency LOC s ( Table 44 ), acute risks from direct effects of sulfometuron methyl on mammals is not exp ected from the modeled uses.

The chronic LOC for mammals was not exceeded for the modeled uses. Predicted residues of sulfometuron methyl on different food types was compared to size class adjusted NOAELs. The highest RQ (0.07) occurred for the 15g mam mal ( Table 45 ) which is below the Agency’s LOC of 1.0 for chronic effects to terrestrial animals. Therefore, chronic risks from direct effects of sulfometuron methyl on mammals are not considered likely.

4.2.2.3. Non

- target Terrestrial

- p hase Amphibians, Reptiles, and
Beneficial Insects

EFED currently uses data on surrogate species (birds) to assess non

- target terrestrial phase amphibians and reptiles and does not derive risk quotients for terrestrial non

- target insects. Based

on the eval uation of potential risks to birds as surrogates for reptiles, potential risks to reptiles and terrestrial phase amphibians is also considered lower than the Agency’s concern level.

As previously discussed, EFED does not currently estimate risk quotient s for terrestrial non

target invertebrates. However, s ubmitted terrestrial insect toxicity data , based on tests with honeybees , suggest that sulfometuron methyl is practically non

- toxic to bees ( LD 50 

### of >100 μg/bee ). The mode of action of sulfometuron me thyl suggests it is likely not to be highly toxic

to terrestrial invertebrates. To the extent that honey bees are representative of the sensitivity of insects and other terrestrial invertebrates to sulfometuron methyl, p otential risk to terrestrial

insect s and invertebrates in treatment area is expected to be minimal.

4.2.3. Risk to Terrestrial Plants

4.2.3.1. Tier 1 Modeling of Runoff and Spray Drift

Results presented in Section 4.1 using the TerrPlant model indicate the modeled uses of sulfometuron methyl result in exposures to non

- endangered and endangered plants adjacent to treated areas that exceed the Agency’s LOC of 1.0. Both monocots and dicots appear highly

### 95 sensitive to sulfometuron methyl, with dicots appearing t o be the more sensitive group of plants. At the maximum aerial application rate of 0.375 lb ai/A, the maximum predicted EEC resulting

from combined drift and runoff to semi

- aquatic areas (0.21 lb ai/A) exceeded terrestrial monocot and dicot EC25 values by approximately 1000 and 6500 times, respectively ( Table 48 ). For endangered monocots and dicots where a more sensitive endpoint is used (NO A EC), the predicted EEC for combined drift and runoff were 4800 and 7100 fo r monocots and dicots, respectively. For the spray drift analysis, predicted EECs were compared to results from the vegetative vigor test, which resulted in RQs of 500 and 1000 for non

- endangered monocots and dicots respectively ( Table 48 ). RQ values for endangered monocots and dicots resulting from drift from aerial application were 2200 and 19000 for monocots and dicots, respectively.

These high RQ values are generally consistent with results from other sulfo nylurea herbicide risk

assessments both internal and external to the Agency . Furthermore, it is worth noting that the most sensitive monocot and dicot from the seedling emergence and vegetative vigor test is used to calculate risks to terrestrial plants. However, examination of the sensitivity of the other 9 test species indicates they too would be a t risk from adverse effects of sulfometuron methyl at the modeled application rate. Specifically, the range in EC25s between the least and most sensitive pla nt from the seedling emergence study was about a factor of 75, while that for the vegetative vigor study was a factor of 5 (MRID 435385

- 01). The RQ values for the most sensitive monocot and dicot species are well above this margin. This indicates the pred icted exceedence of the Agency’s LOC would also occur for the 9 other terrestrial plants tested and are not simply a function of a single, highly sensitive species.

Given these high RQ values for terrestrial plants, a more refined spray drift analysis f or exposures to non

- target terrestrial plants in dry and semi

- aquatic areas is provided in Section

4.2.4

. The potential risk to endangered monocots and dicots will be discussed in greater detail

in Section 4.2.8.2

.

4.2.3.2. Field and Greenhouse Studies

Based on a search of EPA’s ECOTOX database, field and greenhouse studies on the effects of sulfometuron methyl or its degradates were reviewed. Most of the field stu dies that passed the ECOTOX and OPP screening criteria were concerned with the efficacy of sulfometuron methyl control of target plants (weeds) and therefore are not considered useful indicators of the effects of sulfometuron methyl on non

- target plant spe cies (See APPENDIX H: Ecological Effects Data

Summaries ). Those studies that contained relevant information on the effects of sulfometuron methyl or its degradates on non

- target plants are summarized below.

In a greenhouse study, Busse et al. (2005) studied the effect of sulfometuron methyl (applied as the formulated product Oust) on ectomycorrhizal formation and seedling growth of three conifer species: ponderosa pine (Pinus ponderosa), Douglas fir ( Pseudo t suga m enziesii ), and white fir ( Abies concolor ). Conifer seedlings (5 replicates) were grown in four different soil types and applied with sulfometuron methyl at 0, 1X and 2X its application rate of 0.14 kg ai/ha (0.125 lb/A). Sulfometuron methyl was applied t o soil at the onset of lateral root formation (approximately 45

- 55 d post planting) due to the high sensitivity of seedlings to sulfometuron methyl applied prior to this time period. Results indicate that ectomycorrhizal formation was not

### 96 inhibited for any conifer regardless of soil type or application rate (1X or 2X). For ponderosa pine, seedling dry weight and root growth (number of root tips/plant) were significantly reduced relative to controls at 0.125 and 0.250 lb ai/A in two of the four soil types. For Douglas fir and white fir, no significant reduction in seedling dry weight occurred at any treatment level. However, root growth was reduced for Douglas fir at 0.125 lb ai/A for three of the four soil types and at 0.25 lb ai/A for the forth soil type . White fir appeared least sensitive to sulfometuron methyl, with significant reductions in root growth at 0.125 lb ai/A in one soil type and at 0.25 lb ai/A in a second soil type. The authors conclude that sulfometuron methyl does not inhibit mycorrhiza l formation at the specified application rates but does inhibit plant growth of ponderosa pine and root growth of all three species, depending on soil type and application rate

. The lowest NOAEC from this study is 1X the application rate or 0.125 lb ai/A, several orders of magnitude above NOECs observed in the seedling emergence and vegetative vigor guideline

studies.

Boyle and Walters (2005) examined the effect of saccharin, a major degradation product of sulfometuron methyl, on resistance of broad bean ( Vicia faba ) to rust fungus. Although not conceived as a degradate study per se, these results nevertheless have some relevance to the ecotoxicology of one of the sulfometuron methyl degradation products. In this study, 200 ml of 0.3 mM saccharin was appl ied either as a soil drench or to foliage of broad bean which were exposed to rust fungus four times over a 14

- d period. Results indicate that saccharin did not induce resistance to rust fungus nor did it significantly affect shoot weight or leaf area. H owever the authors report the number of leaflets formed was significantly reduced relative to controls.

Neary et al. (1984) evaluated the effects of sulfometuron methyl (as the formulated product Oust) on slash pine ( Pinus elliottii ) and loblolly pine ( P inus taeda ) seedlings inhabiting coastal plain flatlands. In this study, 60 trees of each species were exposed to sulfometuron methyl via broadcast spray at 0.50 lb ai/A in a randomized factorial design involving different plot locations, irrigation and f ertilization levels. Although this study was designed primarily to investigate the efficacy of different weed control methods, the authors report ed three months after treatment, application of sulfometuron methyl did not reduce survival of slash or loblol ly pine , suggesting an unboun d ed NOAEC of 0.50 lb ai/A (only dose tested)

.

4.2.3.3. Contaminated Irrigation Water

The potential risks to plants when exposed to irrigation water contaminated with sulfometuron methyl were estimated for both ground water and surfa ce water irrigation sources (Section 4.1.4 ). The EEC for ground water (0.33 ug/L) was calculated using the Tier 1 SCIGROW model ( Table

16 ) while that for surface wate r ( 31 ug/L) was calculated using PRZM/EXAMS from the scenario yielding the highest EECs ( Table 15 ). Comparisons were made to the most sensitive endpoint from vegetative vigor study assuming that runoff of irrigati on water does not occur. Results suggest that sulfometuron methyl levels in irrigation water from ground water sources

would not exceed non

- endangered or endangered species LOCs (i.e, RQs < 1.0). However, RQs based on sulfometuron methyl in irrigation wa ter derived from surface water sources exceed the

### 97 LOCs for both non

- endangered and endangered species (3. 9 and 71 , respectively), thus indicating a potential risk to plants adjacent to fields irrigated with surface water sources.

4.2.4. Refined Spray Drift Ana lysis

As described in Section 3.2.3.1 (Terrestrial Exposure Modeling), a more in

- depth spray drift exposure assessment utilizing Tier I and II AgDRIFT® (version 2.01) was conducted to better characterize potent ial exposure of terrestrial plants. AgDRIFT® is a useful too for evaluating the potential of buffer zones to protect sensitive habitats from undesired exposures. Four different application scenarios were modeled reflecting typical and reasonable worst cas e assumptions regarding potential exposure conditions (labeled A through D in TABLE 20 and TABLE 21 ).

TABLE 52

. RISKS TO TERRESTRIAL PLANTS FROM SPRAY DR IFT
ACCORDING TO DISTANC E DOWNWIND, APPLICAT ION METHOD, AND
DRIFT EXPOSURE CONDI TIONS

DISTANCE

DOWN WIND (FEET) PERCENT OF

APPLICATION

RATE EEC (1) NON

ENDANGERED

PLANTS (2) ENDANGERED

PLANTS (3)

Percent lb ai/A RQ RQ

[A] Ground Application (Low Boom)

0 102.0 0.3822 21233 3 86061

50 1.77 0.0066 367 6667

100 0.95 0.0036 200 3636

200 0.51 0.0019 106 1919

500 0.21 0.0008 44 808

750 0.13 0.0005 28 505

900 0.11 0.0004 22 404

[B] Ground Application (High Boom)

0 106.0 0.3956 21978 399596

50 5.00 0.0187 1039 18889

100 2.48 0.0093 517 9394

200 1.20 0.0045 250 4545

500 0.39 0.0015 83 1515

750 0.22 0.0008 44 808

900 0.17 0.0006 33 606

### 98 [C] Aerial (Following Many Label Recommendations)

0 50.00 0.1874 10411 189293

50 17.12 0.0642 3567 64848

100 9.79 0.0367 2039 37071

200 4.69 0.0176 978 17778

500 1.92 0.0072 400 7273

750 1.39 0.0052 289 5253

900 1.24 0.0046 256 4646

[D] Aerial (High

- End Exposure Scenario)

0 77.35 0.2900 16111 292929

50 38.32 0.1437 7983 145152

100 25.11 0.0941 5228 95051

200 14.07 0.0527 2928 5323 2

500 5.40 0.0203 1128 20505

750 3.82 0.0143 794 14444

900 3.32 0.0125 694 12626

(1) Details of the refined spray drift modeling are provided in Section 3.2.3.1

. (2) Non

- endangered plant RQs based on vegetat ive vigor EC25 for soybean of 1.8 x 10

- 5 lb ai/A (MRID 435385

- 01)

(3) Endangered plant RQs based on vegetative vigor EC05 for soybean of 9.9 x 10

- 7 lb ai/A (MRID 435385

- 01).



### Results from the refined spray drift modeling indicate that RQs exceed the Ag ency LOC of 1.0 for endangered and non

- endangered terrestrial plants based on all four exposure scenarios at the maximum distance modeled (the model limit of 900 ft downwind of the treated field; see

TABLE 20 ). The highest initia l RQ values occurred with ground applications (high and low boom), although RQs dropped substantially as the distance downwind increased. At a downwind distance of 900 ft, RQs dropped by approximately a factor of 1000 and 600 of the edge of field RQs (0 f t) for low boom and high boom ground applications, respectively. The 50 ft buffer resulted in the largest proportional decline in EECs relative to edge of field estimates, declining to 1.7% and 5.0 % of the initial EECs for low and high boom ground applic ations, respectively.

Compared to ground applications, aerial applications resulted in lower initial EECs at the edge of the field (downwind distance = 0), however, the attenuation of EECs with distance downwind was not as great as that observed with grou nd applications. The EECs (and RQs) declined to

### 99 17% and 38% 50 ft from the edge of field for the typical and high end exposure scenarios, respectively. At 900 ft downwind, RQs for non

- endangered plants are approximately 250 and 700 for the typical and hi gh end aerial application exposure scenarios, respectively. For endangered plants, RQs calculated at 900 ft downwind are approximately 4,600 and 12,600 for the typical and high end aerial application exposure scenarios, respectively.

Pertinent to these modeling results are a number of recommendations (but not requirements) on the product labels for sulfometuron methyl. The labels suggest that “The most effective way to reduce drift potential is to apply large droplets (>I50

- 200 microns)”; but there is no specific mandate on the label. Other suggestions on the label include: that boom height less than 10 feet decreases the potential for spray drift from helicopter or aircraft applications, For ground applications; the applicator receives the following directions: “Setting the boom at the lowest height that provides uniform coverage and reduces the exposure of droplets to evaporation and wind.” The label notes that drift is minimized when the wind speed is between 3 and 10 mph.

4.2.5. Review of Incident Data

An analysis of the ecological incidents associated with a pesticide application (or misapplication) is an important part of EPA’s ecological risk assessment because such information can help

establish additional lines of evidence to the risk assessment co nclusions. A search of EPA’s Ecological Incident Information System (EIIS) was conducted in September, 2007 which revealed 35 incidents reports for sulfometuron methyl with varying degrees of confidence in the causal association. Of these 35 incidents, o ne was classified as highly probable, 20 were classified as probable and 14 were classified as possible (“ APPENDIX E: Adverse Ecological Incidents Associated with Sulfometuron Methyl Use ”) . Only the incidents classified as either highly probable or prob able are discussed further here.

Highly Probable Incidents. The incident classified as highly probable is worthy of discussion here because it is one of the few incidents involving sulfonylurea herbicides where positive findings o f pesticide residues were reported. In this case (Incident Report 1011666

- 001), Oust herbicide (containing sulfometuron methyl) was applied by the Bureau of Land Management (BLM) personnel to approximately 22,000 acres of Idaho forest and grassland in the autumn of 2000 for weed control. These areas were severely damaged or burned by wildfires that occurred the previous year. Following the aerial application of Oust at a rate of 0.0625 lb ai/A, drought and windy conditions (up to 20

- 40 mph) caused pestic ide drift, presumably via erosion of dry treated soils. Thousands of acres were alleged to have been affected, including sugar beets, small grains, garlic, potato, corn, and alfalfa. Soil residues of sulfometuron methyl measured on BLM land ranged from 0 .079 to 0.82 ppb. Documentation by the State of Idaho Dept. of Agriculture showed that in one case, there was evidence to show that sulfometuron methyl was present 13 miles from the application site. Crop damage was estimated to be in excess of $72

milli on.

Probable Incidents. Of the 20 probable incidents involving sulfometuron methyl, 5 involved accidental misuse and all but one of the remaining involved registered uses. Regarding the application method, the majority of probable incidents involved gro und application, although about one third of the incident reports did not contain information on the application method.

### 100 Relative to the type of application site, 7 involved railroad or road rights of way and 6 involved agriculture sites. In terms of rou te of exposure, pesticide drift (either alone or in combination with runoff) was reported for 11 probable incidents, while runoff (either alone or in combination with drift) was reported for 9 probable incidents. A total of 19 probable incidents reported for sulfometuron methyl involved damage to terrestrial plants and only one reported damages to aquatic plants and animals.

Although these sulfometuron methyl ecological incident reports do not conclusively establish sulfometuron methyl as the cause of t he reported damages, in the aggregate they suggest that

non

- target terrestrial plants in particular can be susceptible to both sulfometuron methyl drift and runoff, which was found to be the pathway and receptor of greatest concern in this risk

assessment. The also are consistent with the risk assessment findings of no significant risk of direct toxicity to aquatic and terrestrial animals.

4.2.6. Overall Ecological Risk Conclusions

The results of this screening risk assessment indicate that potential risks fr om direct effects to aquatic and terrestrial animals from exposure to sulfometuron methyl modeled at the maximum annual application rate (0.375 lb ai/A) are below the Agency’s LOCs. Therefore, risk from direct effects to aquatic and terrestrial animals is considered unlikely. Given the mode of action of sulfometuron methyl (ALS inhibitor), the potential for direct effects to aquatic and terrestrial plants is indicated by this screening level risk assessment. Based on a refined analysis of

sulfometuron me thyl spray drift, RQs for terrestrial plants exceed the Agency’s LOC at 900 ft downwind from a treated field in all four application scenarios evaluated. While the potential for direct effects to aquatic and terrestrial animals is considered small, the po tential exists for indirect effects on animals due to impairment of aquatic and terrestrial plants. Specifically, direct effects to plant species could present an indirect risk at the higher levels of organization (i.e. population, trophic level, communit y, and ecosystem). Field studies are not available to quantify actual risk to plant and animal communities in forest/edge and wetland/riparian habitats. However, in terrestrial and shallow

- water aquatic communities, plants are the primary producers

upon which the succeeding trophic levels depend. If the available plant material is impacted due

to the effects of sulfometuron methyl , this may have negative effects not only on the herbivores, but throughout the food chain. Also, depending on the severity o f impacts to the plant communities [i.e., forests, wetlands, ecotones (edge and riparian habitats)], community assemblages and ecosystem stability may be altered (i.e. reduced bird populations in edge habitats; reduced riparian vegetation resulting in incr eased light penetration and temperature in aquatic habitats, loss of cover and food for fish). In addition, riparian vegetation, which is a significant component of the food supply for aquatic herbivores and detritivores provides habitat (i.e. leaf packs, materials for case

- building for invertebrates) may also be affected.

### 101 4.2.7. Endocrine Effects

EPA is required under the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act (FQPA), to develop a screening program to deter mine whether certain substances (including all pesticide active and other ingredients) “ may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate

. ” Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC), EPA determined that there was a scientific basis for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC’s recommendation that the Program include evaluations of potential effects in wildlife. When the appropriate screening and/or testing protocols being considered under the Agency’s EDSP have

been devel oped, sulfometuron methyl may be subjected to additional screening and/or testing to better characterize effects related to endocrine disruption.

4.2.8. Federally Threatened and Endangered (Listed) Species

Both acute endangered species and chronic risk LOCs ar e considered in this screening

- level risk assessment of pesticide risks to listed species. Endangered species acute LOCs are a fraction of

the non

- endangered species LOCs or, in the case of endangered plants, RQs are derived using lower toxicity endpoints than non

- endangered plants. Therefore, concerns regarding listed species within a taxonomic group are triggered in exposure situations where restricted use or acute risk LOCs are triggered for the same taxonomic group. The risk assessment also includes

an evaluation of the potential probability of individual effects for exposures that may occur at the established endangered species LOC in both the risk characterization and the endangered species sections. This probability is calculated using the established dose/response relationship and assumes a probit (probability unit) dose/response relationship. This analysis is present below.

4.2.8.1. Action Area

For listed species assessment purposes, the action area is considered to be the area potentially

affected direc tly or indirectly by the Federal action and not merely the immediate area involved in the action. At the initial screening

- level, the risk assessment considers broadly described taxonomic groups and so conservatively assumes that listed species within tho se broad groups

are co

- located with the pesticide treatment area. This means that terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site and aquatic animals are assumed to be located in a surface water body adjacent t o the treated site. The assessment also assumes that the listed species are located within an assumed area that has the relatively highest potential exposure to the pesticide, and that exposures are likely to decrease with distance from the

treatment area

.

If the assumptions associated with the screening

- level action area result in RQs that are below the listed species LOCs, a "no effect" determination conclusion is made with respect to listed species in that taxa, and no further refinement of the actio n area is necessary. Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no concern for indirect

### 102 effects upon listed species that depend upon the taxonomic group covered by the RQ as a resource. However, in situations wher e the screening assumptions lead to RQs in excess of the listed species LOCs for a given taxonomic group, a potential for a "may affect" conclusion exists and may be associated with direct effects on listed species belonging to that taxonomic group or

may extend to indirect effects upon listed species that depend upon that taxonomic group as a resource. In such cases, additional information on the biology of listed species, the locations of these species, and the locations of use sites and could be conside red along with available information on the fate and transport properties of the pesticide to determine the extent to which screening assumptions regarding an action area apply to a particular listed organism. These subsequent refinement steps could consi der how this information would impact the action area for a particular listed organism and may potentially include areas of exposure that are downwind and downstream of the pesticide use site.

The results of this screening risk assessment indicate that di rect effects to plant species could present an indirect risk at the higher levels of organization (i.e. population, trophic level, community, and ecosystem). The distance from the treated area that risks could extend is greater than 900 feet based on AgDR IFT spray drift modeling. Therefore, an action area for endangered species cannot be defined at this time for this assessment. We note that, while the AgDISP

model with Gaussian extension model is available for extending predictions of deposition from

sp ray drift beyond 1000 feet the exceedances of levels of concern for non

- target plants are likely

to ext end well beyond 1000 feet given the trends observed with AgDRIFT up to 900 feet. This is evident from the risk quotient calculations for terrestrial pla nts exposed to spray drift in TABLE

52 ( the RQ range at 900 feet ranged from 22 to 12626 using different ground and aerial application condition and equipment assumptions).

4.2.8.2. Taxonomic Groups Potentially at Risk

T h is screening level risk assessment for endangered species indicates that sulfometuron methyl exceeds the Endangered Species LOCs for the specified use scenario for the following taxonomic groups:

- Terrestrial plants: monocots and dicots adjacent to trea ted areas, semi

aquatic areas, and drift for turf use at a single application rate of 0. 375 lbs ai/A via ground or aerial spray.

- Freshwater, estuarine and marine aquatic vascular and nonvascular

plants adjacent to treated areas receiving a combination of runoff and spray drift at a single application rate of 0. 375 lbs ai/A

.

No LOC s were exceeded for birds, mammals, reptiles, terrestrial

- phase amphibians, fish, invertebrates, or aquatic

- phase amphibians.

Discussion of Risk Quotients

. For a screening level risk assessment, EFED determines what endangered species may be affected by performing a screening level assessment. If the RQs from this assessment do not exceed the listed species LOCs, endangered species may not be

### 103 a ffected. However, the Agency’s LOC for endangered aquatic plants and terrestrial plants is

exceeded for the use s of sulfometuron methyl as outlined in previous sections. Should estimated exposure levels occur in proximity to listed resources, the available screening level information suggests a potential concern for direct effects on listed terrestrial and aquatic vascular plants and species that rely on these taxa for survival, growth, or reproduction.

Probit Dose Response Relationship

. A probit dose response analysis is usually per formed for aquatic and terrestrial animal toxicity studies for which slopes with 95% confidence intervals are available

. The probit slope response relationship is evaluated to calculate the chance of an individual event corresponding to the listed species acute LOCs. It is important to note that the IEC model output can go as high as 1 x 10 16 

### or as low as 1 x 10 - 16 

### in estimating the event probability. This cut

- off is a limit in the Excel spreadsheet environment and is not to be interpr eted as an agreed upon upper or lower bound threshold for concern for individual effects in any given listed species. To accomplish this interpretation, the Agency would use (1) the slope of the dose response relationship available from the toxicity study used to establish the acute toxicity measurement endpoints for each animal taxonomic group; (2) an assumption of a probit dose response relationship; (3) a mean estimate of slope consistent with current Agency statistical procedures; and (4) a lower limit to the estimate of individual effect chance based on what could be calculated by Excel spreadsheet "Normdist" function. . In cases where dose

response curves are unavailable, event probabilities are calculated for the listed species LOC

based on a defaul t slope assumption of 4.5 as per original Agency assumptions of typical slope cited in Urban and Cook (1986).

For sulfometuron methyl, LC 50 

### or EC 50 

### values were not achieve d in any of the aquatic or terrestrial animal acute toxicity studies. Therefore, it is not possible to estimate the slope and confidence limits directly from these studies. In lieu of such information, EFED default values are used for the slope (4.5) and confidence intervals (2 to 9) and applied to the LOC values. Probability of an ind ividual effect from sulfometuron methyl was estimated at the acute endangered species LOC for aquatic and terrestrial animals. This analysis is presented in the following table.

For aquatic organisms, the LOC for endangered species is 0.05. The RQ is the ratio of exposure to toxicity, so at the point where that ratio equals 0.05, there is a 1 in 418 million chance of an individual being affected. The uncertainty in this number lies primarily in whether the actua l exposure of sensitive species is likely to equal that modeled. For birds , terrestrial

- phase Taxa Probit Slope Endangered Species

LOC Estimated Probability of an

Individua l Effect at the Endangered Species LOC Comment

Fish 4.5 (2

– 9) 0.05 1 in 4 x 10 8

(1 in 2 x 10 2 to 1 in 2 x 10 31 ) Data insufficient to allow for probit slope derivation; therefore, the default slope of 4.5

with lower and upper bounds of 2

– 9 was used. A quatic

Invertebrates 4.5 (2

– 9) 0.05 1 in 4 x 10 8

(1 in 2 x 10 2 to 1 in 2 x 10 31 )

Birds 4.5 (2

– 9) 0.1 1 in 2.9 x 10 5 (1 in 44 to

1 in 9 x 10 18 )

Mammals 4.5 (2

– 9) 0.1 1 in 2.9x 10 5 (1 in 44 to

1 in 9 x 10 18 )

### 104 amphibians, reptiles and mammals, the endangered species LOC is 0.1. The chance of one individual being affected at an RQ equal to the LOC is 1 in 294,000

Beca use the screening level risk assessment indicates that sulfometuron methyl uses exceed the endangered species LOC for terrestrial and aquatic plants, a ‘may affect’ designation can not be precluded based on this assessment. Additionally, the acute level o f concern for terrestrial and aquatic vascular plants is exceeded. The Agency considers this to be indicative of a potential for adverse effects to those listed species that rely either on a specific plant species (plant species obligate) or multiple plan t species (plant dependant) for some important aspect of their life cycle. Further analysis regarding the overlap of individual species with each use site is required prior to determining the likelihood of potential impact to listed species. Such a refin ement is outlined in the following sections.

Data Related to Under

- represented Taxa

. Data are not available to evaluate effects to under

represented taxa.

Implications of Sublethal Effects

. Sublethal effects were not observed in acute aquatic and

terre strial animal studies. Chronic studies were available for freshwater invertebrates, but not fish, birds or mammals. The chronic RQ for freshwater invertebrates did not exceed the c hronic

LOC . Similarly for fish, a chronic RQ, calculated from an NOAEC esti mated using acute

chronic ratio, did not exceed the chronic LOC. For birds, analysis of reproductive NOAECs from other sulfonylurea herbicides suggests that while potential chronic risks from sulfometuron methyl cannot be ruled out, they are considered u nlikely. For mammals, results from a developmental toxicity test indicate the RQ does not exceed the chronic LOC, however, no data were available on the chronic, reproductive effects of sulfometuron methyl to mammals.

Indirect Effects Analysis

. The n on

- endangered and endangered species LOCs for non

- target plants were exceeded for both terrestrial (monocots and dicots) and aquatic plants (vascular, nonvascular) l ocated adjacent to treated areas, in semi

- aquatic areas, and by spray drift for the

scenari os analyzed. The guideline plant studies indicate direct adverse effects to seedling emergence, vegetative vigor, and aquatic vascular and non

- vascular plants, as well as non

- lethal

effects such as chlorosis, growth retardation, necrosis, and unusual pigm entation.

Damage to non

- target plants may be sufficient to prevent the plant from competing successfully with other plants for resources and water. Sulfometuron methyl may increase a plant’s susceptibility to disease and can disrupt nutrient cycling in soil by inhibiting the ability of enzymes to break down cellulose and thereby, decompose plant material. Endangered species may be especially impacted by exposure to sulfometuron methyl because of the impact of the loss of a few individuals to the populati on. There is a potential concern for listed species with either broad or narrow dependencies on impacted plant species/populations/communities for habitat, feeding or cover requirements. In terrestrial and shallow

- water aquatic communities, plants are the primary producers upon which the succeeding trophic levels depend. If the available plant material is impacted due to the effects of sulfometuron methyl , this may have negative effects not only on the herbivores, but also throughout the food chain. In addi tion, depending on the severity of impacts to the plant community [i.e., forest, wetlands, ecotones

### 105 (edge and riparian habitats)], assemblages and ecosystem may be altered (i.e., reduced bird populations in edge habitats, reduced riparian vegetation result ing in increased light penetration and temperature in aquatic habitats, loss of cover and food for fish).

Critical Habitat

. In the evaluation of pesticide effects on designated critical habitat, consideration is given to the physical and biological feat ures (constituent elements) of a critical habitat identified by the U.S

. Fish and Wildlife and National Marine Fisheries Services as essential to the conservation of a listed species and which may require special management considerations or protection. The evaluation of impacts for a screening level pesticide risk assessment focuses on the biological features that are constituent elements and is accomplished using the screening

- level taxonomic analysis (risk quotients, RQs) and listed species levels of

c oncern (LOCs) that are used to evaluate direct and indirect effects to listed animals.

The screening

- level risk assessment has identified potential concerns for indirect effects on listed species for those animals dependant upon aquatic plants, and terres trial and semi

- aquatic plants. In light of the potential for indirect effects, the next step for EPA and the Service(s) is to identify which listed species and critical habitat are potentially implicated. Analytically, the identification of such species and critical habitat can occur in either of two ways. First, the agencies could determine whether the action area overlaps critical habitat or the occupied range of any listed species. If so, EPA would examine whether the pesticide's potential impacts on

non

- endangered species would affect the listed species indirectly or directly affect a constituent element of the critical habitat. Alternatively, the agencies could determine which listed species depend on biological resources, or have constituent eleme nts that fall into, the taxa that may be directly or indirectly impacted by the pesticide. Then EPA would determine whether use of the pesticide overlaps the critical habitat or the occupied range of those listed species. At present,

the information revi ewed by EPA does not permit use of either analytical approach to make a definitive identification of species that are potentially impacted indirectly or critical habitats that is potentially impacted directly by the use of the pesticide. EPA and the Servi ce(s) are working together to conduct the necessary analysis.

This screening

- level risk assessment for critical habitat provides a listing of potential biological features that, if they are constituent elements of one or more critical habitats, would be o f potential concern. These correspond to the taxa identified above as being of potential concern for indirect effects and include the following: aquatic plants, and terrestrial and semi

- aquatic plants. This list should serve as an initial step in problem formulation for further assessment of critical habitat impacts outlined above, should additional work be necessary.

Direct Effect Co

- occurrence Analysis. Because the Endangered Species LOC for terrestrial and aquatic plants is exceeded for the proposed use of sulfometuron methyl, LOCATES would usually be run for all listed terrestrial and aquatic plants (monocots, dicots, ferns, lichen and conf/cycds) to determine the potential for co

- occurrence of listed plant species location with areas of expected pes ticide use. However, no preliminary analysis was performed for non

- crop uses of sulfometuron methyl because the LOCATES tool does not include county

- level location information for the proposed non

- crop uses of sulfometuron methyl. Consequently, based on th e information available at this step in the assessment process, it is presumed that all listed plant species are potentially directly affected from the broad range of sulfometuron methyl proposed

### 106 uses which include vegetative management in railroad, utilit y, and roadside rights

- of

- ways, forestry, tree plantations, industrial sites, and road construction. These uses do not have a geographically distinct attribute which can be used to define the co

- occurrence of listed species

in the LOCATES database. Addit ional analysis of listed plant locations, refinement of the action area associated with sulfometuron methyl, and the biology of the potentially affected species would be needed before an effects determination can be made for any of the co

- located species

i dentified by this assessment.

Indirect Effect Co

- occurrence Analysis

. The screening

- level RQ for terrestrial monocots and dicots and aquatic nonvascular and vascular plants exceeds the LOC for endangered species. In accordance with established procedure s such findings suggest a potential concern for indirect effects to listed animal species with both narrow (i.e., species that are obligates or have very specific habitat or feeding requirements) and general dependencies (i.e., cover type requirements) on plants as a resource or important habitat component. LOCATES would usually

be used to preliminarily identify listed animal species that are located within the counties in USA

where sulfometuron methyl could be used. This analysis would consider all animal taxonomic groups (i.e., birds, mammals, terrestrial and aquatic

- phase amphibians, reptiles, insects, fish, bivalves, crustaceans, arachnids, and gastropods). However, no preliminary analysis was

available for non

- crop use of sulfometuron methyl because the LOCATES tool does not include

county

- level location information for the n on

- crop use s of sulfometuron methyl . Consequently, based on the information available at this step in the assessment process, it is presumed that all listed plant species are potenti ally directly affected from the broad range of sulfometuron methyl proposed uses which include vegetative management in railroad, utility, and roadside rights of ways, forestry, tree plantations, industrial sites, and road construction. These uses do not have a geographically distinct attribute which can be used to define the co

- occurrence of listed species

in the LOCATES database. Additional analysis of listed plant locations, refinement of the action

area associated with sulfometuron methyl, and the bio logy of the potentially affected species would be needed before an effects determination can be made for any of the co

- located species identified by this assessment.

The following table provides listed taxonomic groups that may be at risk from direct or indirect effects due to applications of sulfometuron methyl for vegetative management uses nationwide.

Table 53

. Listed Taxonomic Groups Potential ly at Risk from Direct or Indirect Effects of Sulfometuron Methyl Application for Vegetative Management Throughout the U.S.

Listed Taxon Direct

Effects Basis for Direct Effects Concern Indirect

Effects Basis for Indirect Effects Concern

Terrestrial and

Semi

- Aquatic

Plants

– monocots and

dicots Yes The endangered species LOC is

excee ded for terrestrial plants. Yes Potential concerns from shifts in plant community structure and function due to from selective impacts on plant species.

Terrestrial

Invertebrates No Sulfometuron methyl is practically nontoxic to honeybees, suggesting no Yes Potential concerns for terrestrial invertebrates that use plants for habitat, feeding, or cover

### 107 direct effect concerns for terrestrial

invertebrates. requirements.

Birds and Reptiles (1) No The LOC is not exceeded Yes Potential concerns for birds and reptiles use plants for habitat, feeding, or cover requirements.

Terrestrial

- phase Amphibians (1) No The LOC is not exceeded Yes Potential concerns for terrestrial

- phase amphibians that use plants for habitat, feeding, or cover requirements.

Mammals No The LOC is not exceeded Yes Potential concerns for mammals that use plants for habitat, feeding, or cover requirements. Aquatic Vascular

Plants and

Nonvascular

Plants Yes The endangered species LOC is exceeded for aquatic vascular and

nonvascular plant s. No Potential concerns from shifts in plant community structure and function due to from selective impacts on plant species.

Freshwater and

Marine/Estuarine fish and Aquatic

phase Amphibians (2) No The LOC is not exceeded Yes Potential concerns for fish and aquatic

- phase amphibians that use plants for habitat, feeding, or cover requirements.

Freshwater and

Marine/Estuarine

Crustaceans No The LOC is not exceeded Yes Potential concerns for crustaceans that use plants for habitat, feeding, or cover requir ements.

Mollusks No The LOC is not exceeded Yes Potential concerns for mollusks that use plants for habitat, feeding, or cover requirements.
(1) Birds are used as surrogate species for terrestrial

- phase amphibians and reptiles; therefore, potential direct and indirect effects to endangered avian, terrestrial

- phase amphibians and reptilian species are considered equivalent.
(2) Fish are used as a surrogate for aquatic phase amphibians; therefore, potential direct and indirect effects to endangered fis h and aquatic

- phase amphibian species are considered equivalent.



## 4.3. Description of Assumptions, Limitations, Uncertainties, and Data Gaps

4.3.1. Assumptions and Limitations Related to E ffects on all Species

**•** Indirect Effects. Perhaps one of the largest uncertain ties associated with the effects assessment for sulfometuron methyl is the inability to adequately quantify potential indirect effects resulting from adverse effects on aquatic and terrestrial plants. Specifically, direct effects to plant species could pr esent an indirect risk at the higher levels of organization (i.e. population, trophic level, community, and ecosystem). Field studies are not available to quantify actual risk to plant and animal communities in forest/edge and wetland/riparian habitats. However, in terrestrial and shallow

- water aquatic communities, plants are the primary producers upon which the succeeding trophic levels depend. If the available plant material is impacted due to the effects of sulfometuron methyl , this may have negative effects not only on the herbivores, but throughout the food chain. Also, depending on the severity of impacts to the plant communities [i.e., forests, wetlands, ecotones (edge and riparian habitats)], community assemblages and ecosystem stability may be a ltered (i.e. reduced bird populations in edge

### 108 habitats; reduced riparian vegetation resulting in increased light penetration and temperature in aquatic habitats, loss of cover and food for fish). In addition, riparian vegetation, which is a significant co mponent of the food supply for aquatic herbivores and detritivores provides habitat (i.e. leaf packs, materials for case

- building for invertebrates) may also be affected.

**•** Toxicity of Degradation Products. In this screening level ecological risk assessmen t, the lack of data on major degradates is considered one of the primary limitations and uncertainty regarding the overall risk associated with one of the registered use of sulfometuron methyl. Since the chemical structure and environmental behavior of th e major degradates differ substantially from the parent molecule (i.e., degradation involves cleavage of the sulfonylurea bridge, essentially splitting the molecule in half), it could not be assumed with reasonable confidence that the degradates were equiv alent in toxicity to the parent compound. Limited toxicity data was available for one major degradation product: saccharin. However, this information was oriented towards human health concerns and lacked endpoints of ecological relevance that would be co nsidered useful in this ecological risk assessment. This finding is somewhat expected since saccharin is used as a sugar substitute in the U.S. food supply.

**•** Variability in Species Sensitivity

. Although the screening risk assessment relies on a

selected toxicity endpoint from the most sensitive species tested, it does not necessarily mean that the selected toxicity endpoints reflect sensitivity of the most sensitive species existing in a given environment. The relative position of the most sensitive speci es tested in the distribution of all possible species is a function of the overall variability among species to a particular chemical. In the case of listed species, there is uncertainty regarding the relationship of the listed species’ sensitivity and the most sensitive species

tested. For terrestrial and aquatic animals, uncertainty associated with the limited quantification of interspecies variability in sensitivity to sulfometuron methyl would probably not impact the risk assessment results substantial ly, given that sulfometuron methyl is practically nontoxic to animals. For aquatic and terrestrial plants, variability in sensitivity across species could substantially alter the risk assessment results (e.g., higher RQs if more sensitive species were tes ted). However, toxicity data were available for 5 species of aquatic plants and 10 species of terrestrial plants distributed broadly across taxonomic groups, which suggests that at least a reasonable range of plant sensitivity to sulfometuron methyl was c aptured in this risk assessment.

**•** Effects of Pesticide Mixtures: This assessment considered only exposure to the active ingredient sulfometuron methyl. However, simultaneous exposures to multiple chemical and physical stressors are likely to occur in the environment. No acceptable data were located that evaluated potential additive, synergistic, or antagonistic interactions between sulfometuron methyl and other chemical stressors. If such interactions occur, then risks

could be under or over

- estimated.

### 109 4.3.2. Assumptions and Limitations Related to E ffects on Aquatic Species

**•** Study Quality and Data Gaps. Several studies did not meet guideline requirements and therefore were classified as either supplemental or unacceptable. Specifically, all acute toxicity data for marine and estuarine organisms were classified as supplemental due to uncertainty associated with the bioavailability of sulfometuron methyl in these tests. However, conclusions of this risk assessment would not likely change with submission of

a dditional acute toxicity data for marine and estuarine organisms because EECs were several orders of magnitude below reported toxicity limits. The freshwater chr onic test

with fathead minnow w as found to be unacceptable, again because of uncertainty and

v ariability associated with measurement of soluble (bioavailable) sulfometuron methyl. To address this data gap, acute

- chronic ratios were applied to estimate chronic toxicity to freshwater fish. Results indicate that even with conservative assumptions re garding the selection of the ACR, risks from direct effects of chronic sulfometuron methyl exposure

to freshwater fish are not likely.

4.3.3. Assumptions and Limitations Related to E ffects on Terrestrial Species

**•** Study Quality and Data Gaps

. Lack of toxicity da ta w as noted for the effect of sulfometuron methyl on avian and mammalian reproduction. For mammals, the NOAEL of 300 mg ai/kg

- bw/d was used from a developmental toxicity study to rabbits. While providing some information on the effect of sulfometuron me thyl on mammalian development during gestational exposure, results from this study do not capture the potential effects of sulfometuron methyl on reproductive endpoints including courtship, mating, sex ratios and offspring survival, growth and development.

**•** Vascular Plant Reproduction . Terrestrial and aquatic plants appear most sensitive to sulfometuron methyl exposure. While toxicity data were available for endpoints related to systemic growth, seedling emergence and visual injury, these guideline stud ies are not designed to capture reproductive endpoints. Therefore, to the extent that plant reproduction is more sensitive to sulfometuron methyl exposure compared to growth or visual injury

- related endpoints, risks to aquatic and terrestrial plants may b e underestimated.

**•** Use of Maximum Pesticide Application Rate. In this screening level analysis, risks of sulfometuron methyl to non

- target plants and animals was evaluated using the maximum label application rate (0.375 lb ai/A). This was performed in concordance with the goals of a screening assessment: to rule out receptors and exposure pathways and identify those pathways where potential risks are evident. Other label application rates are available for sulfometuron methyl as identified in see Secti on 3.1 (Use Characterization) . The lower range of application rates are mostly within a factor of 10 of the maximum application rates. Given that RQs for terrestrial and aquatic plants predicted using the maxi mum application rate are well above a factor of 10, use of the lower application rates would not likely change the risk assessment conclusions.

### 110 

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USDA. 2004. Sulfometuron Methyl

- Human and Ecological Risk Assessment: Final Report. Prepared for: U.S. Dept. Agriculture, Forest Service. Contract No. GS

- 10F

- 0082F.

USEPA. 1998. Guidelines for Ecological Risk Assessment. U.S. Environmental Protection Agency

, Risk Assessment Forum, Washington, DC, EPA/630/R095/002F

USEPA. 2004. Overview of the Ecological Risk Assessment Pr ocess in the Office of Pesticide Programs, U.S. Environmental Protection Agency. Endangered and Threatened Species Effects Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C. January 23, 2004.

USEPA. 2007. Ecological Risk Assessment: Flazasulforon. Office of Pesticide Programs, Environmental Fate and Effects Division, Washington, DC.

Weber, J.B., G.G. Wilkersona and C.F. Reinhardt. 2004 Calculating pesticide sorption coefficients ( K d 

### ) us ing selected soil properties. Chemosphere 55:157

– 166

William A. Battaglin, Edward T. Furlong, Mark R. Burkhardt, C. John Peter. (2000). Occurrence of Sulfonylurea, Sulfonamide, Imidazolinone, and other Herbicides in

### 112 Midwestern Rivers, Reservoirs, and Gro und Water. The Science of the Total Environment 248:

123

- 133

Willis, G. H. and L..L. McDowell, 1987. Pesticide Persistence on Foliage. in Reviews of Environmental Contamination and Toxicology . 100:23

- 73.

Zhu QZ, Degelmann P, Niessner R, Knopp D. Sele ctive trace analysis of sulfonylurea herbicides in water and soil samples based on solid

- phase extraction using a molecularly imprinted polymer. Environ Sci Technol. 2002 Dec 15;36(24):5411

- 20

### 113 

## 6. APPENDICES

A PPENDIX A : STRUCTURES AND CHEMI CAL NAMES OF
SULFOMETURON METHYL METABOLITES

Chemical Structures

Trivial or common names Company id or similar alternate names

Full chemical names

Sulfometuron methyl

DPX

- T5648; DPX

- 5648; IN

- T5648 ; IN

T5648

- 18 Methyl 2

- (4,6

- dimethylpyrimidin

- 2

-

ylcarbamoylsulfamoyl )benzoate Saccharin

IN

- 581 1,2

- Benzisothiazol

- 3(2H)

- one, 1,1

- dioxide

Sulfometuron pyrimidine amin e IN

- X 0 993; IN

- X993; PA 4,6

- Dimethyl

- 2

- pyrimidinamine
4,6

- dimethyl

- 2

- pyrimidinamine Sulfometuron sulfonamide

IN

- D5803; SA; methyl phenylsulfonamid e Methyl 2

- (aminosulfonyl)benzoate.

2

- (Aminosulfonyl)

- benzoic acid, methyl ester

### 114 Pyrimidine

- ol

IN

- 11859 4,6

- Dimethyl

- 2

- pyrimidinol Sulfometuron free acid

FA

- SM; IN

- T6385

2

- [[[[(4,6

- Dimethyl

- 2

- pyrimidinyl)amino]carbonyl]amino]sulfonyl]

- benzoic acid



### O O H

S

O O

N

H H

0 Free acid Sulfonamide

FA

- Sulfonamide; Free acid; IN

- D5119

2

- (Aminosulfonyl)benzoic acid

### 115 

## APPENDIX B: ENVIRONMENTAL FATE D ATA REQUIREMENTS

E nvironmental Fate Data Requirements for Sulfometuron Methyl

Guideline Data Requirement Test Material MRID Study

Classification Data Requirement

Met? More

Data

Needed?

[161

- 1] Hydrolysis sulfometuron methyl 42715201 Acceptable Yes No

[161

- 2] Direct photolysis

in water sulfometuron methyl 42182401

43174101 Acceptable Yes No

[161

- 3] Photolysis on soil sulfometuron methyl 41420601 Acceptable Yes No

[161

- 4] Photodegradation

in Air NA NA not required NA NA

[162

- 1] Aerobic soil

metabolism sulfometuron methyl 42091401 Acceptable Yes No

[162

- 1] Aerobic soil

metabolism sulfometuron methyl 4317 4102

and

245375 Acceptable Yes No

[162

- 2] Anaerobic Soil

Metabolism NA NA ref 162

- 3 Yes No

[162

- 3] Anaerobic aquatic

metabolism sulfometuron methyl 42091402

and

43188601 Acceptable Yes No

[162

- 3] Anaerobic aquatic

metabolism sulfometuron methyl 4413 010

- 20 (143540) Acceptable Yes No

[162

- 4] Aerobic aquatic

metabolism sulfometuron methyl 42091403

and

43174103 Acceptable Yes No

[163

- 1] Adsorption/ Desorption sulfometuron methyl 42789301 Acceptable Yes No

[163

- 1] Adsorption/ Desorption Pyrimidine

a mine 42789301 Acceptable Yes No

[163

- 1] Adsorption/ Desorption saccharin 42789301 Acceptable Yes No

[163

- 2] Laboratory Volatility NA NA not required NA NA

### 116 E nvironmental Fate Data Requirements for Sulfometuron Methyl

Guideline Data Requirement Test Material MRID Study

Classification Data Requirement

Met? More

Data

Needed?

[163

- 3] Field Volatility NA NA not required NA NA

[164

- 1] Terrestrial Field Dissipation Sulf ometuron methyl 43212101

and

43637101 Acceptable Yes No

[164

- 2] Aquatic Field Dissipation No study NA NA NA NA

[164

- 3] Forestry Dissipation Sulfometuron methyl 42091404

and

43174104 Acceptable Yes N o

[165

- 4] Accumulation in

Fish Waived NA NA NA NA

[165

- 5] Accumulation in aquatic non

- target organism (crayfish) Waived NA NA NA NA

[166

- 1] Ground Water

small scale prospective No Study (not required) NA NA NA NA

### 117 

## APPENDIX C : ECOLOGICAL AQUATIC E XPOSURE
MODELING

Multiple PRZM

- EXAMS runs at single sites using different application date assumptions: Summary tables and sample input files

PRZM / EXAMS multiple application date assumption modeling: Sorted (by 21

- day exposure estimates) List of 1 in 10 year return frequency for Various Exposu re Durations

- Aerial application using the Texas / Barton Springs Salamander scenario and Port Arthur Texas meteorological data.

DATE Peak 96 hr 21 Day 60 Day 90 Day Yearly 30

- Year

09

- 10 49.472 47.733 43.139 33.437 27.192 7.450 4.065

12

- 05 36.060 34.87 9 30.054 20.981 16.522 4.884 2.415

30

- 08 32.625 31.363 27.061 21.239 17.805 5.586 2.992

20

- 08 30.949 29.903 25.886 19.000 15.626 4.967 2.808

10

- 08 30.601 29.743 25.451 18.437 15.009 5.118 2.625

29

- 09 29.668 28.637 25.585 20.158 16.479 5.638 3.434

19

- 1 0 27.970 27.134 24.748 20.222 14.168 5.007 3.257

21

- 06 27.622 26.773 22.849 16.110 12.749 3.867 1.986

19

- 09 27.223 26.413 23.585 18.717 15.510 4.768 3.042

31

- 07 26.516 25.765 22.706 16.344 13.286 4.136 2.180

29

- 10 25.269 24.619 22.258 17.629 13.919 4.7 50 3.091

01

- 07 22.932 22.383 19.082 13.514 10.730 3.479 2.005

09

- 09 22.903 22.276 19.198 14.672 12.353 4.305 2.653

02

- 05 21.703 20.976 18.837 13.835 11.003 3.254 1.923

11

- 06 21.795 20.881 17.461 12.414 9.917 3.114 2.057

11

- 07 21.572 20.696 17.817 12.8 18 10.264 3.220 1.900

01

- 06 21.430 20.570 17.539 12.484 9.849 2.948 1.944

12

- 04 20.368 19.822 17.811 13.507 10.822 3.210 1.767

22

- 05 20.277 19.455 16.521 12.017 9.476 2.927 1.730

21

- 07 20.064 19.205 16.126 11.487 9.199 2.939 1.960

23

- 03 18.931 18.470 17.070 13.343 10.972 3.333 1.469

22

- 04 18.700 18.253 15.762 11.875 9.712 2.980 1.705

21

- 02 17.801 17.397 16.164 13.272 11.138 3.448 1.372

02

- 04 17.776 17.228 15.491 11.441 9.083 2.691 1.492

13

- 03 13.882 13.555 12.579 9.934 8.174 2.522 1.361

01

- 02 10.3 87 10.157 9.247 7.440 6.303 2.010 1.164

11

- 02 9.156 8.956 8.476 6.885 5.827 1.856 1.028

03

- 03 8.483 8.348 7.965 6.554 5.458 1.673 1.031



### Sample input file, Texas Rights of Way Scenario, multi

- run

### 118 Output File: Sfmt_TXrway3_03

- 13_19

- 10

Metfile: w12917.dvf

PRZM scenario: RightOfWayBSS.txt

EXAMS environment file: pond298.exv

Chemical Name: Sulfometuron Methyl

Description Variable

Name Value Units Comments Molecular weight mwt 364.38 g/mol Henry's La w Const. henry atm

- m^3/mol Vapor Pressure vapr 5.40E

- 16 torr Solubility sol 2.44E+02 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L Photolysis half

- life kdp 0 days Half

- life Aerobic Aquatic

Metabolism kbacw 292 days Hal f

- l ife Anaerobic Aquatic

Metabolism kbacs 76 days Half

- life

Aerobic Soil Metabolism asm 61 days Half

- life Hydrolysis: pH 5 8.8 days Half

- life Hydrolysis: pH 7 139 days Half

- life Hydrolysis: pH 9 224 days Half

- life

Method: CAM 2 intege r See PRZM manual Incorporation Depth: DEPI 4 cm Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.95 fraction

Spray Drift DRFT 0.05 fraction of application rate applied to pond Application Date Date 19

- 10 dd/mm or dd/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5 Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF none none, monthl y or total

PRZM / EXAMS multiple application date assumption modeling: Sorted (by 21

- day exposure estimates) List of 1 in 10 year return frequency for Various Exposure Durations

- **Ground** application using the Texas / Barton Springs Salamander scenario and Port Arthur Texas meteorological data.

DATE Peak 96 hr 21 Day 60 Day 90 Day Yearly 30

- Year

09

- 10 39.996 38.810 34.507 27.791 21.603 6.172 2.769

30

- 08 27.463 26.544 22.992 16.878 13.881 3.981 1.858

10

- 08 26.457 25.737 21.998 15.903 12.933 4.017 1.5 82

20

- 08 25.924 24.975 21.491 15.348 12.142 3.568 1.734

### 119 12

- 05 24.414 23.588 20.408 14.954 12.292 3.887 1.786

29

- 09 22.197 21.464 18.230 12.916 10.207 3.063 1.297

21

- 02 19.582 19.078 17.362 14.267 9.967 3.834 2.171

19

- 09 20.200 19.568 17.226 13.829 11. 935 3.896 2.025

23

- 03 18.665 18.003 16.757 12.319 9.776 2.873 1.427

21

- 06 19.217 18.836 16.746 13.167 9.414 3.404 2.094

29

- 10 19.558 18.836 16.599 12.734 10.828 3.451 1.788

12

- 04 20.279 19.472 16.553 11.997 9.737 2.922 1.350

02

- 05 18.100 17.658 16.324 12.773 10.517 3.192 1.213

31

- 07 17.670 17.268 16.064 13.203 11.090 3.430 1.271

19

- 10 17.914 17.355 15.893 12.284 9.832 2.912 1.344

09

- 09 18.029 17.253 14.468 10.227 8.170 2.563 1.316

11

- 07 17.639 16.926 14.442 10.422 8.227 2.487 1.340

11

- 06 17.352 16 .770 14.329 10.381 8.286 2.588 1.210

21

- 07 16.643 16.227 14.228 10.881 9.213 2.866 1.560

22

- 04 15.884 15.392 13.645 9.657 7.589 2.260 1.105

13

- 03 16.502 15.962 13.631 9.510 7.553 2.318 1.371

22

- 05 14.795 14.375 13.013 9.882 7.969 2.400 1.258

01

- 07 15. 183 14.562 12.420 9.190 7.325 2.219 1.299

01

- 06 12.986 12.623 12.026 9.563 7.867 2.421 1.183

02

- 04 13.375 12.975 11.704 8.802 7.076 2.106 1.148

01

- 02 9.992 9.763 8.891 7.158 6.070 1.927 1.043

11

- 02 8.705 8.496 8.064 6.565 5.558 1.766 0.907

03

- 03 8.054 7.928 7.533 6.214 5.176 1.580 0.902 PRZM / EXAMS multiple application date assumption modeling: Sorted (by 21

- day exposure estimates) List of 1 in 10 year return frequency for Various Exposure Durations

- **Aerial** application using the California Red

- Legg ed Frog scenario and Astoria, Oregon meteorological data.

DATE Peak 96 hr 21 Day 60 Day 90 Day Yearly 30

- Year

13

- 03 11.346 11.125 10.256 8.581 7.493 2.779 1.194

29

- 10 11.134 10.934 10.233 8.604 6.248 2.715 1.610

19

- 10 11.046 10.854 10.202 8.547 6.635 2.788 1.629

11

- 02 10.995 10.813 10.059 8.418 7.375 2.811 1.648

01

- 02 10.284 10.105 9.405 7.891 6.932 2.696 1.317

23

- 03 9.964 9.816 9.119 7.570 6.591 2.455 1.145

21

- 02 9.996 9.786 9.049 7.574 6.639 2.528 1.351

22

- 04 9.587 9.432 8.660 7.130 6.146 2.227 0.826

03

- 03 8.919 8.739 8.146 6.838 5.990 2.250 1.360

12

- 04 8.775 8.674 8.055 6.686 5.789 2.111 0.859

09

- 10 8.495 8.366 7.783 6.526 5.464 1.963 1.081

19

- 09 8.390 8.237 7.550 6.240 5.484 1.987 0.998

12

- 05 7.639 7.473 6.855 5.553 4.763 1.709 0.563

09

- 0 9 7.313 7.145 6.531 5.356 4.704 1.549 0.913

02

- 04 6.253 6.167 5.795 4.808 4.167 1.544 0.867

### 120 02

- 05 6.182 6.045 5.514 4.535 3.905 1.417 0.765

01

- 06 5.513 5.389 5.037 4.131 3.543 1.272 0.749

29

- 09 5.466 5.382 4.939 4.118 3.627 1.094 0.754

20

- 08 5.518 5.3 87 4.841 3.886 3.353 1.394 0.683

30

- 08 4.742 4.628 4.216 3.437 2.999 1.026 0.695

22

- 05 4.562 4.466 4.086 3.335 2.859 1.049 0.509

21

- 06 4.304 4.211 3.833 3.084 2.643 0.980 0.554

01

- 07 3.938 3.853 3.516 2.863 2.437 0.866 0.466

10

- 08 3.738 3.644 3.277 2. 627 2.265 0.911 0.542

21

- 07 3.677 3.584 3.273 2.643 2.281 0.855 0.490

11

- 07 3.705 3.607 3.250 2.577 2.200 0.802 0.505

11

- 06 3.351 3.273 2.999 2.427 2.072 0.750 0.461

31

- 07 3.347 3.266 2.936 2.353 2.028 0.856 0.538



### Sample Input Files:

Output File: Sfm t_CArway4_02

- 04

Metfile: w94224.dvf

PRZM scenario: CArightofwayRLF.txt

EXAMS environment file: pond298.exv

Chemical Name: Sulfometuron Methyl Description Variable Name Value Units Comments Molecular weight mwt 36 4.38 g/mol Henry's Law Const. henry atm

- m^3/mol Vapor Pressure vapr 5.40E

- 16 torr Solubility sol 2.44E+02 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L Photolysis half

- life kdp 0 days Half

- life Aerobic Aquatic Metabolism kbacw 292 days Half

- life Anaerobic Aquatic Metabolism kbacs 76 days Half

- life

Aerobic Soil Metabolism asm 61 days Half

- life Hydrolysis: pH 5 8.8 days Half

- life Hydrolysis: pH 7 139 days Half

- life Hydrolysis: pH 9 224 days Half

- life

Method: CAM 2 in teger See PRZM manual Incorporation Depth: DEPI 4 cm Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.95 fraction Spray Drift DRFT 0.05 fraction of application rate applied to pond Application Date Date April 2 dd/mm or d d/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

### 121 FEXTRC 0.5 Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF none none, monthly or total



## Single PRZM

- EXAMS runs for different sites: Sample EEC Summary tables and sample input files

Florida Citrus scenario

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.0323 1.642 1.592 1.403 1.072 1.000 0.340

0.0645 1.490 1.446 1.30 0 1.026 0.942 0.318

0.0968 1.487 1.446 1.279 1.020 0.864 0.292

0.1290 1.338 1.297 1.143 0.933 0.848 0.260

0.1613 1.199 1.172 1.056 0.918 0.782 0.248

0.1935 1.057 1.038 0.939 0.787 0.676 0.216

0.2258 1.057 1.028 0.928 0.767 0.666 0.210

0.2581 1.056 1. 027 0.924 0.756 0.636 0.203

0.2903 1.056 1.026 0.921 0.731 0.606 0.198

0.3226 1.054 1.026 0.921 0.724 0.601 0.188

0.3548 1.053 1.025 0.921 0.721 0.600 0.187

0.3871 1.053 1.025 0.916 0.720 0.600 0.186

0.4194 1.053 1.025 0.915 0.720 0.595 0.185

0.4516 1.053 1.025 0.914 0.717 0.594 0.184

0.4839 1.053 1.024 0.914 0.714 0.593 0.184

0.5161 1.053 1.024 0.911 0.713 0.591 0.183

0.5484 1.053 1.024 0.910 0.709 0.587 0.182

0.5806 1.053 1.024 0.909 0.704 0.583 0.182

0.6129 1.053 1.024 0.908 0.703 0.579 0.181

0.6452 1.053 1.023 0.907 0.700 0.578 0.179

0.6774 1.053 1.023 0.907 0.700 0.578 0.177

0.7097 1.053 1.023 0.906 0.697 0.576 0.177

0.7419 1.052 1.023 0.905 0.695 0.573 0.177

0.7742 1.052 1.022 0.904 0.694 0.570 0.176

0.8065 1.052 1.022 0.904 0.694 0.57 0 0.175

0.8387 1.052 1.021 0.902 0.693 0.570 0.175

0.8710 1.052 1.021 0.902 0.691 0.570 0.174

0.9032 1.052 1.021 0.901 0.688 0.567 0.174

0.9355 1.052 1.020 0.900 0.688 0.566 0.173

0.9677 1.050 1.019 0.899 0.687 0.565 0.172

0.1000 1.472 1.431 1.265 1.011 0.863 0.28865 Average of yearly

averages: 0.20175

Output File: Sfmt_FLcitrus1

Metfile: w12844.dvf

PRZM scenario: FLcitrusSTD.txt

### 122 EXAMS environment file: pond298.exv

Chemical Name: Sulfometuron Methy l

Description Variable

Name Value Units Comments Molecular weight mwt 364.38 g/mol Henry's Law Const. henry atm

- m^3/mol

Vapor Pressure vapr 5.40E

16 torr Solubility sol 244 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L Photolysis half

- life kdp 0 days Half

- life Aerobic Aquatic

Metabolism kbacw 292 days Half

- life Anaerobic Aquatic

Metabolism kbacs 76 days Half

- life

Aerobic Soil Metabolism asm 61 days Half

- life Hydrolysis: pH 5 8.8 days Half

- life Hydrolysis: pH 7 139 days Half

- life Hydrolysis: pH 9 224 days Half

- life

Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 4 cm Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.95 fraction

Spray Drift DRFT 0.05 fraction of application rate applied to pond Application Date Date 3

- Jan dd/mm or dd/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FE XTRC 0.5 Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF none none, monthly or total



### Florida Turf Scenario

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly

0.032 0.707 0.686 0.604 0.457 0.372 0.128

0.06 5 0.639 0.622 0.558 0.429 0.354 0.109

0.097 0.464 0.451 0.398 0.303 0.259 0.090

0.129 0.379 0.367 0.323 0.255 0.221 0.076

0.161 0.360 0.353 0.318 0.244 0.218 0.071

0.194 0.226 0.220 0.200 0.168 0.150 0.048

0.226 0.213 0.207 0.186 0.162 0.141 0.045

### 123 0. 258 0.212 0.206 0.185 0.153 0.130 0.042

0.290 0.212 0.206 0.184 0.147 0.125 0.041

0.323 0.212 0.206 0.184 0.146 0.121 0.039

0.355 0.211 0.206 0.184 0.145 0.120 0.037

0.387 0.211 0.206 0.184 0.144 0.120 0.037

0.419 0.211 0.205 0.183 0.144 0.119 0.037

0.452 0.211 0.205 0.183 0.144 0.119 0.037

0.484 0.211 0.205 0.183 0.143 0.119 0.037

0.516 0.211 0.205 0.183 0.143 0.119 0.037

0.548 0.211 0.205 0.182 0.142 0.117 0.037

0.581 0.211 0.205 0.182 0.141 0.117 0.036

0.613 0.211 0.205 0.182 0.141 0.117 0.036

0.645 0.211 0.205 0.182 0.141 0.116 0.036

0.677 0.211 0.205 0.182 0.141 0.116 0.036

0.710 0.211 0.205 0.181 0.140 0.115 0.036

0.742 0.211 0.205 0.181 0.139 0.115 0.035

0.774 0.211 0.204 0.181 0.139 0.114 0.035

0.806 0.211 0.204 0.181 0.139 0.114 0.0 35

0.839 0.211 0.204 0.181 0.139 0.114 0.035

0.871 0.210 0.204 0.180 0.138 0.114 0.035

0.903 0.210 0.204 0.180 0.138 0.113 0.035

0.935 0.210 0.204 0.180 0.138 0.113 0.035

0.968 0.210 0.204 0.180 0.138 0.113 0.034

0.100 0.456 0.442 0.391 0.298 0.255 0.089 Average of yearly

averages: 0.046883

Inputs generated by pe5.pl

- November 2006

Data used for this run: Output File: Sfmt_FLturf2

Metfile: w12834.dvf

PRZM scenario: FLturfSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Sulfometuron Methyl

Description Variable

Name Value Units Comments Molecular weight mwt 364.38 g/mol Henry's Law Const. henry atm

- m^3/mol

Vapor Pressure vapr 5.40E

16 T orr Solubility sol 244 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L Photolysis half

- life kdp 0 D ays Half

- life Aerobic Aquatic

Metabolism kbacw 292 D ays Half

- life Anaerobic Aquatic

Metabolism kbacs 109 D ays Half

- life

### 124 Aerobic Soil Me tabolism asm 61 D ays Half

- life Hydrolysis: pH 5 8.8 D ays Half

- life Hydrolysis: pH 7 139 D ays Half

- life Hydrolysis: pH 9 224 D ays Half

- life

Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 C m Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 3

- Jan dd/mm or dd/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

U PTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA

Pond

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

Inputs generated by pe5.pl

- November 2006

Data used for this run: Output File: Sfmt_FLturf1

Metfile: w12834.dvf

PRZM scenario: FLturfSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Sulfometuron Methyl Descripti on Variable Name Value Units Comments Molecular weight mwt 364.38 g/mol Henry's Law Const. henry atm

- m^3/mol Vapor Pressure vapr 5.40E

- 16 Torr Solubility sol 2.44E+02 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L Photolys is half

- life kdp 0 Days Half

- life Aerobic Aquatic

Metabolism kbacw 292 Days Half

- life Anaerobic Aquatic

Metabolism kbacs 76 Days Half

- life

Aerobic Soil Metabolism asm 61 Days Half

- life Hydrolysis: pH 5 8.8 Days Half

- life Hydrolysis : pH 7 139 Days Half

- life Hydrolysis: pH 9 224 Days Half

- life

Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 4 cm Application Rate: TAPP 0.42 kg/ha Application Efficiency: APPEFF 0.95 fraction

### 125 Spray Drift DRFT 0.05 fraction of application rate applied to pond Application Date Date 3

- Jan dd/mm or dd/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA

Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)



## APPENDIX D: TERRPLANT SPREADSHEE T

( 

## TerrPlant Version 1.2.2)

Table D

- 1. Chemical Identity.

Chemical Name Sulfometuron

M ethyl
PC code 122001

Use non
- crop vegetative management, forestry, rights of way Application Method ground

Application Form water dispersible granule Solubility in Water (ppm) 244 (pH 7)

Table D

- 2. Input parameters used to derive EECs.

In put Parameter Symbol Value Units

Application Rate A 0.375 lb a.i./A

Incorporation I 1 none
Runoff Fraction R 0.05 none

Drift Fraction D 0.01 none

Table D

- 3. EECs for Sulfometuron Methyl. Units in lb a.i./A.

Description Equation EEC

Runoff to dry areas (A/I)*R 0.01875

Runoff to semi

- aquatic

areas (A/I)*R*10 0.1875

Spray drift A*D 0.00375 Total for dry areas ((A/I)*R)+(A*D) 0.0225

Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.19125

Table D

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

Seedling Emergence Vegetative Vigor
Plant type EC 25 NOAEC EC 25 NOAEC

### 126 Monocot 1.90E

- 04 4.30E

- 05 3.70E

- 05 8.40E

- 06

Dicot 3.20E

- 05 2.90E

- 05 1.80E

- 05 9.90E

- 07

Table D

- 5. RQ values for plants in dry and semi

- aquati c areas exposed to Sulfometuron Methyl through runoff and/or spray drift.*

Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed 118.42 1006.58 101.35

Monocot listed 523.26 4447.67 446.43

Dicot non

- listed 703.13 5976.56 208.33

Dico t listed 775.86 6594.83 3787.88

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

### 127 

## APPENDIX E : ADVERSE ECOLOGICAL INCIDENTS ASSOCIATED WITH
SULFOMETURON METHYL USE

Incident ID Use Site Start

Date Legality Cer tainty State County Year Total Magnitud

e Appl. Rate Appl.

Method Affected Species Product

I011666

- 001 Municpal operation 01

- Nov

- 00 Registered use Highly

Probable ID 2000 Thousand
s Of Acres 1 Oz/Acre Aerial 1 OUST

I013086

- 001 Right

- of

way, rail 15

- Jun

- 02 Registered use Probable WA Kittitas 2002 Unknown 3 Oz Per 15
Gallons Spray 1 Oust

I009556

- 043 Agricultural

area 15

- May

- 92 Registered use Probable CO Costilla 1992 $4,400,00

0 Damages N/R Spray 1 OUST

I005972

- 001 PLANT
SITE 01

- Sep

- 97 Registered use Probab le TX 1997 N/A N/R 1 OUST

I006010

- 003 Utility plant 19

- Aug

- 97 Misuse (accidental) Probable MS 1997 Unknown RUN

OFF 1

I000903

- 005 Forest 01

- Sep

- 91 Misuse (accidental) Probable TX Anderson 1991 N/R 500 Oz/

3000 Acres Spray 1 OUST

I000903

- 002 Agricult ural

area 01

- Jan

- 94 Registered use Probable TX Cherokee 1994 N/R N/R Spray 1 OUST

I006010

- 001 Right

- of

way, road 20

- Aug

- 97 Misuse (accidental) Probable LA 1997 Unknown N/R N/R 1

I000903

- 003 Agricultural

Area 01

- Jan

- 94 Registered use Probable TX 1994 N /R N/R Spray 2,3,4 OUST

I000903

- 001 Agricultural

area 01

- Sep

- 91 Registered use Probable TX Anderson 1991 N/R 2 Oz/25

- 30
Gal Water Spray 1 OUST

I006010

- 002 Agricultural

area 20

- Aug

- 97 Misuse (accidental) Probable TX 1997 Unknown N/R N/R 1

I007269

- 001 A gricultural

area 21

- May

- 98 Registered use Probable CA Fresno 1998 All N/R N/R 1 OUST

I007269

- 002 YARD 29

- May

- 98 Registered use Probable TN Davidson 1998 All N/R N/R 1 OUST

I015217

- 001 Forest 21

- May

- 04 Registered use Probable OH Gallia 2004 8000 Sq

Ft 3 O z/Acre Spray 1 Oust

herbicide

I015832

- 001 Right

- of

way, road 14

- Dec

- 04 Registered use Probable LA Lafayette 2004 N/R Spray 1 Oust

I017481

- 001 Turf, 24

- May

- 06 Undetermined Probable WI Waukesha 2006 Unknown Unknown N/R 1 DuPont

### 128 Incident ID Use Site Start

Date Legality Cer tainty State County Year Total Magnitud

e Appl. Rate Appl.

Method Affected Species Product

residential Oust

I015576

- 0 01 Right

- of

way, road 01

- Apr

- 04 Registered use Probable OR Multnomah 2004 $40,000 N/R N/R 1 Landmark

MP

I016302

- 001 Right

- of

way, road 23

- May

- 05 Registered use Probable WA Grant 2005 Less Than

An Acre N/R Spray 1 Oust

I016429

- 001 Industrial

site 13

- Jun

- 0 5 Registered use Probable WA Grant 2005 $90,000 Damage 5 Oz/Acre Spray 1 Oust

I015440

- 001 Right

- of

way, utility 01

- Jun

- 03 Misuse (accidental) Probable MN Benton 2003 2 Acres 5 Oz/Acre Spray 1 Oust

I013194

- 001 Right

- of

way, rail 02

- Jul

- 02 Registered use P robable ND Walsh 2002 10 Acres 3 Oz/15
Gals Water Spray 1 OUST

I014409

- 011 Right

- of

way, road 03

- Jun

- 92 Registered use Possible WA Walla Walla 1992 Not Given 1

B000601

- 010 Right

- of

way 25

- May

- 84 Registered use Possible CA Fresno 1984 N/R Spray 1 Oust

I015796

- 001 Right

- of

way, utility 08

- Nov

- 04 Registered use Possible KY Jessamine 2004 1

- 4 Acres 3 Oz/Acre Nr 1 Oust XP

Herbicide

B000601

- 011 N/R 16

- May

- 88 Registered use Possible CA Kern 1988 N/R 1 Oust

I000071

- 001 Peach 01

- Jan

- 92 Registered use Poss ible SC Saluda 1992 Numerous

Trees N/R N/R 1 OUST

B000601

- 009 N/R 23

- May

- 85 Undetermined Possible LA Acadia 1985 Less Than

50 Acres Spray 1 Oust

I015265

- 001 Seedling 01

- Mar

- 04 Registered use Possible TX Cass 2004 Unknown Unknown Unknow

n 1 Oustar

I01668 0

- 001 Right

- of

way 06

- Apr

- 05 Undetermined Possible OR Douglas 2005 13 Acres Spray 1

I009556

- 005 Agricultural

area Misuse (accidental) Possible NC 0 Unknown N/R N/R 1 OUST

B000601

- 001 N/R 04

- May

- 88 Undetermined Possible CA Kern 1988 NR NR 1 Oust

I01 6312

- 001 Forest 01

- Apr

- 05 Undetermined Possible OR Benton 2005 300 Acres 2 Lb/Acre Spray 1 Westar

B000601

- 008 Right

- of

way, road 23

- May

- 85 Registered use Possible LA Acadia 1985 Nr Spray 1 Oust

B000601

- 007 Right

- of

way, road 23

- May

- 85 Registered use Pos sible NE Scotts Bluff 1985 Nr 2 Oz/Acre 1 Oust



### Source: USEPA, OPP Ecological Incident Information System, October, 2007. Affected Species: 1 = terrestrial plants, 2 = aquatic plants, 3 = terrestrial animals, 4= aquatic animals

### 129 

## APPENDIX F : T

- REX OUTPUT

Table F

- 1. T

- REX Model Inputs Used for Sulfometuron Methyl

TREX MODEL INPUTS

Chemical Name: Sulfometuron methyl

Use: non

- crop; forest, rights

- of

- way

Product name and form: Oust (et al): water dispersible graunule % A.I. (leadi ng zero must be entered for formulations <1% a.i.): 100.00%

Application Rate (lbs/A): 0.375

Half

- life (days): 35

Application Interval (days):

Number of Applications: 1

Note: Sources of wildlife diet are assumed to be available for

less than one year for this model.

Endpoints

Avian Indicate test species below

LD50 (mg/kg

- bw) 4650.00 2 (mallard)
LC50 (mg/kg

- diet) 4600.00 2 (mallard) NOAEL (mg/kg

- bw) 2

NOAEC (mg/kg

diet) 1

Enter the Mineau et al. Scaling

Fact or 1.15

Mammals

LD50 (mg/kg

- bw) 5000.00 Rat

LC50 (mg/kg

- diet)

Reported Chronic Endpoint (mg/kg

- bw/d) 549.00 Scaled to 350 g

from Rabbit Developmental Tox Study

Is dietary concentration (mg/kg

- diet) reported from the available chronic mammal study? (yes or no) no

Enter dietary concentration (mg/kg

- diet)

Estimated Chronic Diet Concentration Equivalent to Reported Chronic Daily Dose 10980 mg/kg

- diet based

on standard FDA

lab rat conversion

### 130 Table F

- 5. T

- REX Output: Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants/

Small Insects Fruits/Pods/

Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

10980 90.00 0.01 41.25 0.00 50.63 0.00 5.63 0.00

Size class not us ed for dietary risk quotients

Table F

- 6: T

- REX Output: 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/

Lar ge Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 1206.61 85.81 0.07 39.33 0.03 48.27 0.04 5.36 0.00 1.19 0.00

35 976.28 59.30 0.06 27.18 0.03 33.36 0.03 3.71 0.00 0.82 0.00

1000 422.27 13.75 0.03 6.30 0.01 7.73 0.02 0.86 0.00 0.19 0.00

Table F

- 2. T

- REX Output: Upper B ound Kenaga, Acute Avian Dose

- Based Risk Quotients

Size Class (grams) Adjusted

LD50 EECs and RQs

Short Grass Tall

Grass Broadleaf

Plants/

Small Insects Fruits/Pods/

Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

20 2414.40 102.50 0.04 46.98 0.02 57.66 0.02 6.41 0.00

100 3073.65 58.45 0.02 26.79 0.01 32.88 0.01 3.65 0.00

1000 4341.65 26.17 0.01 11.99 0.00 14.72 0.00 1.64 0.00

Table F

- 3. T

- REX Output: Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50 EECs and R Qs

Short Grass Tall Grass Broadleaf

Plants/

Small Insects Fruits/Pods/

Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

4600 90.00 0.02 41.25 0.01 50.63 0.01 5.63 0.00
Size class not used for dietary risk quotients

Table F

- 4. T

- REX Outp ut: 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 85.81 0.01 39.33 0.00 48.27 0.00 5.36 0.00 1.19 0.00

35 8891.40 59.30 0.01 27.18 0.00 33.36 0.00 3.71 0.00 0.82 0.00

1000 3845.80 13.75 0.00 6.30 0.00 7.73 0.00 0.86 0.00 0.19 0.00

### 131 

## AP PENDIX G: MODELING OF TERRESTR IAL PLANT
EXPOSURE FROM CONTAM INATED IRRIGATION WA TER

The following calculations were used for determining risk quotients for plants when groundwater or surface water contaminated by sulfometuron methyl is applied to areas as irrigation water and subsequently drift to adjacent areas.

SURFACE WATER IRRIGATION:

Assume a 1

- acre field is irrigated with one inch of water containing 31 μg/L (or ppb) sulfometuron methyl (peak EEC for surface water, Table 15).

One acre has 6,272, 640 square inches of surface area. A 1

- acre field irrigated with 1 acre

- inch of water (6,272,640 cubic inches of water) would have been treated with 3,630 cubic ft of water (6,272,640 cubic inches x 1 cubic ft/1728 cubic inches). Converting to gallons, t he field has received 27,156 gallons of water (3,630 cubic ft x 7.481 gallons/cubic ft). On a pounds per acre basis, 1 inch of water applied to a 1

- acre field weighs 226,625 lbs (27,156 gallons x 8.3453 lbs/gallon of water).

So, if surface water containi ng 31 ppb sulfometuron methyl is used to provide of 1 acre

- inch of irrigation water, sulfometuron methyl is applied at a rate of:

226,625 lb of water/A x 31 ppb (ai sulfometuron methyl ) = 0.00703 lbs ai/A sulfometuron methyl 1,000,000,000

Therefore, the risk quotient for sensitive plants adjacent to a field that is irrigated with surface water containing 31 ppb (or μg/L) sulfometuron methyl is calculated as follows:

EEC (spray drift) = application rate of contaminated irrigation water (0. 00703 lb ai/A) * 1% drift

= 7.03 x 10 - 5 

### lb ai/A.

Non

- endangered Plant RQ:

From 1 acre

- inch of surface water: EEC/EC 25 

### for vegetative vigor = 7.03 x 10 - 5 

### lbs ai/ A = 3.9

1.8 x 10 - 5 

### lbs ai/A

E ndangered Plant RQ:

From 1 acre

- inch of s urface water: EEC/EC 05 

### for vegetative vigor =

7.03 x 10 - 5 

### lbs ai/ A = 71

9.9 x 10 - 7 

### lbs ai/A

### 132 GROUND WATER IRRIGATION

To calculate risk quotients for plants when ground water contaminated by sulfometuron methyl is applied as irrigation wa ter and subsequently drifts to adjacent areas, the following method was

used.

Assume a 1

- acre field is irrigated with one inch of water containing 0.33 ppb (or μg/L) sulfometuron methyl (peak EEC for ground water, Table 15).

As calculated above, 1 acre

- i nch of irrigation water weighs 226,625 lbs. So, sulfometuron methyl is applied at a rate of:

226,625 lb of water/acre x 0.33 (ai sulfometuron methyl ) = 7.48 x 10 - 5 

### lbs ai/A.
1,000,000,000

Therefore, the risk quotient for sensitive plant s adjacent to the irrigated area with ground water containing 0.33 ppb (or μg/L) sulfometuron methyl is calculated as follows:

EEC (spray drift) = application rate of contaminated irrigation water (7.48 x 10 - 5 

### lb ai/A) * 1%

drift = 7.03 x 10 - 7 

### lb ai/A.

Non

- endangered Plant RQ:

From 1 acre

- inch of ground water: EEC/EC 25 

### for veg.vigor = 7.48 x 10 - 5 

### lb ai/A = 0.04

1.8 x 10 - 5 

### lbs ai/A

E ndangered Plant RQ:

From 1 acre

- inch of ground water: EEC/EC 25 

### for veg.vigor = 7.48 x 10 - 5 

### lb ai/A = 0.76

9.9 x 10 - 7 

### lbs ai/A

### 133 

## APPENDIX H: ECOLOGICAL EFFECT S DATA SUMMARIES

I. OPP Guideline Toxicity Studies

Freshwater Fish, Acute

Bluegill Sunfish, (L epomis macrochirus )

. For bluegill, results from the range finding test indicated no mortality w hen exposed to sulfometuron methyl up to 200 mg ai/L (i.e., LC50 >200 mg/L). Accordingly, a definitive toxicity test was not required and a single treatment test was conducted at the toxicity limit of 150 mg ai/L using technical grade sulfometuron methyl (99.6% ai). Results from the limit test (MRID 435018

- 01 ) indicate no mortality to bluegill at an exposure concentration of 150 mg ai/L. To prevent the formation of chemical precipitate experienced during previous toxicity testing, test solutions were buf fered with 5N sodium hydroxide. This resulted in a greater pH range (7.2

– 9.0) than recommended (7.2

- 7.6) in study guidelines. The study authors reported observing no precipitate or other signs of insolubility during the study. The test concentration w ere measured and found to be within 80% to 120% of nominal. The pH range deviation is therefore considered a necessary byproduct of increasing the solubility of the test chemical. No mortality was observed in the controls. All other test guideline deviat ions are considered minor. This study is classified as acceptable and meets the guideline requirements for acute toxicity to a fresh water fish.

Rainbow Trout, (Oncorhynchus mykiss)

. Similarly for rainbow trout, no mortality was observed in a range findi ng test up to 200 mg ai/L or the follow

- up toxicity limit test at 150 mg ai/L sulfometuron methyl (99.6% ai). Buffering of test solutions was required to prevent formation of precipitates which resulted in a greater pH range (7.9

- 8.7) than recommended (7. 2

- 7.6). The test concentration were measured and found to be within 80% to 120% of nominal. The pH range deviation is therefore considered a necessary byproduct of increasing the solubility of the test chemical. No mortality was observed at 148 mg ai/L (m easured concentration) or in the controls. All other test guideline deviations are considered minor. This study is classified as acceptable and meets the guideline requirements for acute toxicity to a fresh water fish.

Freshwater Invertebrates, Acute

W ater flea ( Daphnia magna ). The toxicity of sulfometuron methyl to freshwater invertebrates is indicated by a 48

- hr acute toxicity test with the water flea, Daphnia magna (MRID 435018

- 03 ). As observed with freshwater fish, no mortality was observed in a ra nge finding test up to 200 mg ai/L or the follow

- up toxicity limit test at 150 mg ai/L sulfometuron methyl (99.6% ai). Buffering of test solutions was required to prevent formation of precipitates which resulted in a greater pH range (8.4

- 9.0) than recomm ended (7.2

- 7.6). No mortality was observed in the 150 mg/L treatment or in the negative control. One daphnid died in the pH adjusted control (mortality 3%). The test concentration was measured and found to be 100% of nominal. The pH range deviation is t herefore considered a necessary byproduct of increasing the solubility of the

test chemical.

### 134 This test was originally classified as supplemental in 1995 by EFED because of concerns over chemical composition of the dilution water (filtered fish tank wate r housing fathead minnows) and the potential for microbial degradation. For the purposes of this risk assessment, this study

was re

- reviewed and upgraded to acceptable. According to the study authors, ammonia levels in the dilution water were not signifi cantly raised and a summary of its chemical composition was provided in an earlier chronic life cycle test with the same organism (MRID 416728

- 06) and found to be acceptable. Furthermore, given the very low hydrophobicity of this chemical,

alteration of i ts bioavailability due to sorption to organic carbon would not likely be significant, even if levels far exceeded those reported in the dilution water from the earlier daphnid study. Lastly, the chemical concentration was verified analytically which confi rmed that significant chemical degradation was not occurring. This study is classified as acceptable and meets the guideline requirements for an acute toxicity study with a freshwater invertebrate.

Estuarine and marine Fish, Acute

S heepshead minnow ( Cy prinodon variegatus )

. The toxicity of sulfometuron methyl to estuarine and marine fish is indicated by a 96

- hr acute toxicity test with the sheepshead minnow, Cyprinodon variegatus conducted at nominal concentrations of sulfometuron methyl (99.1% ai) rangi ng from 15 to 100 mg ai/L (MRID 416728

- 03 ). The LC 50 

### based on measured concentrations from this study was found to be greater than 45 mg ai/L. No mortality or observable signs of sublethal effects occurred in the study except for one dead fish (5%) at 8. 2 mg/L (measured). This study was re

- reviewed for this risk assessment and found to contain several significant deficiencies which render its classification as supplemental. Specifically, measured concentrations ranged widely from test initiation to term ination (4 to 7 times), which is believed due to the formation of an observable precipitate in test solutions. This occurred despite buffering of the dilution water to an initial pH of 8.5 (pH ranged thereafter from 7.4 to 8.5).

Although originally cla ssified as supplemental by EFED in 1993, the study was subsequently upgraded to core/acceptable by EFED in 1994 upon the registrant’s explanation that solubility limits in unbuffered water prevented adequate recovery of sulfometuron methyl from test

soluti ons and that test concentrations were verified analytically. However, while this information may explain the low % of nominal concentrations observed in the study, there was high variability in measured test concentrations with treatments and substantial uncertainty in the actual exposure of organisms to dissolved sulfometuron methyl (no centrifugation of test samples prior to analysis). Although these deficiencies could render the study classification as “unacceptable,” it is considered to provide some u seful information in this risk assessment (i.e., an indication of a lack of toxicity at or near solubility limits in test solutions). Furthermore, when viewed in the context of screening level EECs (i.e., a maximum peak concentration of

0.031 ppm in water ) , the bioavailable (dissolved) portion sulfometuron methyl would have to be approximately 1500

- fold lower than the highest measured test concentration (~45 ppm) in order for risks to be evident. Therefore, this study is classified as supplemental but is not recommended for repeat testing at this time because a repeat test would be highly unlikely to

alter the risk assessment conclusions.

Estuarine and Marine Invertebrates, Acute

### 135 M ysid shrimp, Mysidopsis bahia. For mysids, a 96

- h assay was conducted at nominal concentrations of sulfometuron methyl (99.1%) ranging from 15 to 100 mg ai/L (MRID 416728

- 04). The 96

- h LC 50 

### based on measured concentrations from this study was found to be greater than 44.8 mg ai./L. No mortality or observable signs of subletha l effects occurred in the study at any test concentration or the control. A re

- review of the mysid test indicates it has several significant deficiencies which render its classification as supplemental. Specifically, measured

concentrations of sulfometur on methyl ranged widely from test initiation to termination (3X to 13X in the mysid tests) and were substantially below nominal concentrations. The low % nominal is believed due to the formation of an observable precipitate in test solutions. The low

% n ominal occurred despite buffering of the dilution water to an initial pH of 8.5 (pH ranged thereafter from 7.6 to 8.5). The pH range in the mysid test extended beyond the recommended range in the test guidelines (7.7

- 8.0 for euryhaline shrimp).

Although the mysid study was originally classified as supplemental by EFED in 1993, the study was subsequently upgraded to core/acceptable in 1994 by EFED upon the registrant’s explanation that solubility limits in unbuffered water prevented adequate recovery of

su lfometuron methyl from test solutions and that test concentrations were verified analytically. However, while this information may explain the low % of nominal concentrations observed in the study, there was high variability in measured test concentratio ns with treatments and substantial uncertainty in the actual exposure of organisms to dissolved sulfometuron methyl (no centrifugation of test samples prior to analysis per OPP test guidelines). Although these deficiencies could render the study classific ation as “unacceptable,” it is considered to provide some useful information in this risk assessment (i.e., an indication of a lack of toxicity at or near solubility limits in test solutions). Furthermore, when viewed in the context of screening level

EEC s (i.e., a maximum peak concentration of 0.031 ppm in water)

, the bioavailable (dissolved) portion sulfometuron methyl would have to be approximately 1 3 00

- fold lower than the highest measured test concentration (~ 45 ppm) in order for risks to be evident. Therefore, this study is classified as supplemental but is not recommended for repeat testing at this time because a repeated test would not likely affect the risk assessment conclusions.

Eastern oyster, Crassostrea virginica

. For oysters, a 48

- h assay was conducted on embryos at the same nominal concentrations as used for mysids (MRID 416728

- 05). The 48

- h EC 50 

### based on measured concentrations for this study was found to be greater than 38.2 mg ai/L. No mortality occurred and 99% of the surviving contr ol oysters were normal.

A re

- review of the oyster study indicates it has several significant deficiencies which render its classification as supplemental. Specifically, measured concentrations of sulfometuron methyl ranged widely from test initiation t o termination (up to 3X) and were substantially below

nominal concentrations. The low % nominal is believed due to the formation of an observable precipitate in test solutions. In the oyster test, pH ranged from 7.7 to 8.0. The pH range in the

oyster te st extended beyond the recommended range in the test guidelines (8.0

- 8.3 for stenohaline oysters).

Although this study was originally classified as supplemental by EFED in 1993, it was subsequently upgraded to core/acceptable in 1994 by EFED upon the regi strant’s explanation

### 136 that solubility limits in unbuffered water prevented adequate recovery of sulfometuron methyl from test solutions and that test concentrations were verified analytically. However, while this information may explain the low % of nomin al concentrations observed in the study, there was high variability in measured test concentrations with treatments and substantial uncertainty in the actual exposure of organisms to dissolved sulfometuron methyl (no centrifugation of test samples prior to analysis per OPP test guidelines). Although these deficiencies could render the study classifications as “unacceptable,” it is considered to provide some useful information in this risk assessment (i.e., an indication of a lack of toxicity at or near sol ubility limits in test solutions). Furthermore, when viewed in the context of screening level EECs (i.e., a maximum peak

concentration of 0.031 ppm in water)

, the bioavailable (dissolved) portion sulfometuron methyl would have to be approximately 1000

- fol d lower than the highest measured test concentration (~ 40 ppm) in order for risks to be evident. Therefore, this study is classified as supplemental but is not recommended for repeat testing at this time because a repeated test would not likely affect

th e risk assessment conclusions.

Freshwater Fish, Chronic

A chronic, early life

- stage toxicity test was conducted in 1982 to determine the effect of sulfometuron methyl on fathead minnow embryo hatching, larval survival, and growth (MRID

423857

- 04; Accessi on No. 249796). Fertilized embryos and hatched larvae were exposed to 5 nominal concentrations ranging from 0.15 to 2.5 mg ai/L under flow

- through conditions. Dimethylformamide (DMF) was used as a carrier (0.1 ml/L) and a solvent and negative control

wer e used. Two replicates were used per test treatment, with each replicate containing 50 embryos and subsequent to hatching, 20 larvae. A statistically

- significant reduction in hatching was attributed to the highest test concentration (2.5 mg/L nominal, 1. 16 mg/L measured) using

chi

- square analysis (but not significant using ANOVA). Mean percent hatch was 38% in the highest test concentration compared to 75% in the solvent and negative controls. Larval survival was not significantly affected in any test c oncentration (ranging from 85

- 100%) compared to 92% in the negative control and 95% in the solvent control. Larval growth (length, weight) were also not significantly affected in any test concentration relative to either control. During the last

week of t he test, a diluter malfunction resulted in a precipitous drop in exposure concentrations in all treatments (at or below detection of 0.01 mg/L in several treatments). Thus, the NOAEC and LOAEC from this study (0.71 and 1.16 mg/L, respectively for % hatchin g) were determined by considering only the embryo exposure portion of the study prior up through hatching (i.e., prior to the diluter malfunction).

A re

- review of this study conducted for this risk assessment the study is unacceptable primarily

because of high uncertainty in quantifying exposure experienced by fathead minnows during the test. Specifically, temporal variability in test concentrations exceeded OPP test guidelines of <

1.5X in all test concentrations. Even when measured concentrations from the last week are not considered, the ratio of the highest to the lowest test concentration ranged from 1.6 to 2.7. As reported in the study, the stability of the test substance in the DMF carrier is in question and is thought to be responsible for the lo w measured concentrations (48% of nominal on average).

Follow

- up testing indicated that at the pH of the study (7.2

- 7.5), the solubility of the sulfometuron methyl with the DMF carrier would be approximately 3 mg/L. At higher pH, the

### 137 solubility of sulfom eturon methyl increases substantially (>100 mg/L). At the time this study was conducted (1982), however, pH adjusted test solutions was not conducted reportedly due to lack of knowledge of the NaOH pH adjustment method. However, results from the Daphnia life cycle study discussed below indicate that with appropriate buffering, stable and consistent concentrations are achievable with sulfometuron methyl. Because the NOAEC for fathead minnow from this study (0.71 mg/L) is within an order of magnitude of EE Cs (0.031 mg/L), there is a reasonable probability that a valid NOAEC for chronic effects could fall in the range of the EECs. Finally, the precipitous drop in exposure concentrations brings into question the study findings of a lack of a significant affe ct on fathead minnow larval growth, since exposure was terminated up to a week prematurely. This study is considered unacceptable and does not fulfill the guideline requirements for chronic toxicity to freshwater fish.

Freshwater Invertebrate, Chronic

Chronic toxicity sulfometuron methyl to freshwater invertebrates is indicated by a 21

- day life cycle test conducted on the water flea, Daphnia magna (MRID 416728

- 06). Daphnids (<24

- h old) were exposed to six concentrations of sulfometuron methyl ranging f rom 0.1 to 100 mg/L (nominal) in a static

- renewal system. Reproduction, growth and survival were measured in 7 replicates per treatment (1 organism/rep.), while 3 additional replicates were designated solely for survival measurement (5 organisms/rep.). I n order to promote solubility of the test substance, the pH of the stock solutions of the 25 mg/L and 100 mg/L treatments were adjusted with NaOH to pH 8.5. Both a negative and pH

- adjusted controls were included.

Results indicate that mean measured conc entrations were close to nominal concentrations (i.e., within 20% of the 0.1, 0.39, 1.6, 6.3, 25 and 100 mg/L nominal concentrations). Variability in test concentrations was well within the acceptable limits of 1.5X. Daphnid survival, growth and reproduct ion were not significantly different between negative and pH adjusted controls. Survival and growth (length) were not affected at any test concentration. Reproduction, as measured by the number of neonates produced/daphnid, was not significantly different from negative controls in any treatment (ANOVA, 0.05). Although the Dunnett’s multiple comparison test indicated a marginally significant difference in the 24 mg/L treatment (mean measured concentration), it is not considered statistically valid to apply means testing when ANOVA results indicate lack of significant differences among treatments. Furthermore, an

inconsistent concentration

- response relationship is indicated by the lack of a significant reduction in daphnid reproduction at 97 mg/L (the highe st treatment tested). Therefore, the NOAEC for daphnid reproduction is re

- interpreted as 97 mg/L (unbounded) and the LOAEC is > 97 mg/L. This study is classified as acceptable and meets the guideline requirements for a chronic study using a freshwater in vertebrate.

Aquatic Plants

Green Algae, Selenastrum capricornutum . A tier 2 growth and reproduction study was conducted on the effects of sulfometuron methyl (99.1% ai) on the green algae, S. capricornutum (MRID 416801

- 02). Six test concentrations were evaluated ranging from 0.63 to 20 ug ai/L (nominal). The 120 hr EC 50 

### (reduction in cell density) for S. capricornutum was 4.6 μg ai /L and the NOAEC was 0.63 ug ai/L. At the LOAEC of 1.3 μg/L, growth was reduced approximately

### 138 20%, while the cell growth at the NOAEC showed a slight increase relative to controls. A

monotonic concentration

- response relationship with cell density was observed. These toxicity values are based on reported nominal concentrations. Although the study authors indicate that sample s were taken for analytical measurement and would be analyzed “if deemed necessary,” results from chemical analysis were not provided in the study report. At these concentrations, solubility of the test compound is not expected to be problematic. Therefor e, this test is classified as acceptable and meets the guidelines requirement a test with a freshwater green algal species.

Freshwater and Marine Diatoms ( Navicula pelliculosa and Skeletonema costatum). Preliminary tests with the freshwater diatom ( N. pel liculosa ) and saltwater diatom ( S. costatum ) indicated a lack of toxicity such that Tier II tests were not necessary. Both species were exposed to a nominal ‘limit’ test concentration of 414 ug ai/L (99.2% ai) for 120 hours including negative controls (4 reps each). This ‘limit concentration’ corresponded to the maximum concentration calculated for sulfometuron methyl applied to a 6 in. deep, 1 acre pond. For N. pelliculosa , no significant reduction in cell density was observed following exposure to 370 ug ai/L (measured,

MRID 435385

- 02 ). The pH ranged from 7.4 to 7.5. Similarly for S. costatum

, no significant reduction in cell density was observed following exposure to 410 ug ai/L (measured, MRID

435385

- 02 ). The test pH ranged from 7.9

- 8.7 at test ter mination. Measurements at test initiation and termination indicate stability of sulfometuron methyl in the test solutions. No significant guideline deviations were noted in these studies. These tests are considered acceptable and meet the guideline requi rements for a freshwater and marine diatom.

Bluegreen Algae, Anabena flos

- aquae. A tier 2 test was conducted on the freshwater blue

- green algae, Anabaena flos

- aquae
, at 5 test concentrations of sulfometuron methyl (99.2% ai) ranging

from 14 to180 μg/L (measured values, MRID 435385

- 02 ). Measurements at test initiation and termination indicate stability of sulfometuron methyl in the test solutions. The 120

- hr EC 50 

### (cell density) for Anabaena was calculated as 41.6 μg/L. A NOAEC for cell density wa s calculated as

<14 μg/L (lowest concentration tested). This NOAEC corresponds to a 20% in cell growth relative to controls. This test is considered scientifically sound but is classified as supplemental because a NOAEC was not reached in the study. No other major guideline deviations were apparent in this test.

Duckweed, Lemna gibba

. T he freshwater vascular plant (duckweed) was studied in a 14

- day exposure to sulfometuron methyl (95.7% ai, MRID 435835

- 03) at 5 test doses ranging from

0.13 to 1.0 45 ug ai/L plus a negative control. A total of 3

- 5 plants were tested per replicate with

3

- 5 fronds per plant. The pH of test solutions ranged from 7.5 to 9.4 because test solutions were buffered to maintain adequate solubility. The 14

- day exposure of EC 50 

### and N OAEC for frond count (the most sensitive endpoint tested) were 0.48 and 0.21 μg/L, respectively. Frond counts were reduced 4% at the NOAEC and 20% at the LOAEC (0.32 ug/L). Measurements at test initiation and termination indicate stability of sulfometuro n methyl in the test solutions. Following the 14

- d exposure period, recovery of duckweed was assessed at the end of the study by exposing organisms to untreated medium for an additional 14 days. Effects were expressed as percent inhibition of frond count s and biomass. The results are as follows:

### 139 14

- d Recovery 14

- d Recovery:

14

- d Exposure Conc. Frond Count Inhibition Biomass Inhibition

1.045 ppb 41.1% 38.3% 0.590 ppb 11.8% 10.8% 0.323 ppb 0.6%

- 1.0%

Th e study authors concluded that sulfometuron methyl was phytotoxic to duckweed at

concentrations of > 0.590 ppb and phytostatic at 0.323 ppb. These data suggest that the effects of sulfometuron methyl to aquatic vascular plants may be reversible following 14

- d exposures at selected concentrations (0.323 ppb and below) provided a sufficient recovery period is available. This study is considered acceptable and satisfies the guideline requirement for a toxicity test using an aquatic vascular plant.

Avian, O r al A cute

Mallard duck, Anas platyrhynchos. An acute oral toxicity study with the mallard indicates sulfometuron methyl ( > 93% ai) is practically non

- toxic on an acute basis (MRID 245375). An

oral LD 50 

### of > 4,650 mg ai/kg

- bw was reported in this study (rec alculated by reviewer for % ai). No mortality occurred in any treatment and birds appeared normal throughout the 14

- d test period. Food consumption varied widely across treatments, but did not exhibit a dose

- dependent trend. Weight gain/loss also did not exhibit a dose

- dependent trend within or across sexes. Weight gain in females may have been confounded by induction of the egg laying cycle by the photoperiod used. The guideline requirement (71

- 1) is fulfilled for an acute oral toxicity study

with birds for sulfometuron methyl and the study is classified as acceptable.

Avian, Dietary A cute

Mallard duck, Anas platyrhynchos and bobwhite quail, Colinus virginianus. Two, 8

- d dietary acute toxicity studies were submitted on the effects of sulfometuron met hyl on bobwhite quail and mallard duck (Accession No. 246409 and MRID 71414, respectively). Both tests consisted

of a 5

- d exposure period followed by 3 days of observation. Mortality, food consumption and body weight were measured during the test. Mallar ds were 16 days old while quail were < 14 days old at test initiation, with each test using 10 birds per treatment level. The submitted data indicates that sulfometuron methyl (92 to 95.2% ai) is practically nontoxic to mallard and quail

when administered via subacute, dietary exposure. The 8

- day acute dietary LC 50 

### values for bobwhite quail and mallard are > 5,620 mg ai/kg

- diet and > 4,600 mg ai/kg

- diet , respectively (adjusted by reviewer for & ai). There were no signs of mortality

, clinical toxicity, or a bnormal behavior reported in the studies. The guideline (71

- 2) is fulfilled for a subacute dietary study

with birds and these studies are classified as acceptable.

Mammal, A cute

Rat, Sprague Dawley. The acute toxicity of sulfometuron methyl (technical grade active ingredient) is indicated by an acute, oral toxicity study with the rat (MR ID 43089201 ). In this study, 5 male and 5 female rats were administered a single oral dose of 5000 mg ai/kg

- bw

### 140 technical grade sulfometuron methyl (approx. 100% a.i.) in corn oil via gavage. Rats were observed for mortality, signs of ill health, pharmacologic and toxicological effects for 14 days after dosing. No mortality occurred at 5,000 mg ai/kg

- bw and no clinical signs of toxicity were

observed that were related to sulfometuron methyl exposure. Male and females continued to gain weight throughout the study. An acute, oral LD50 value of >5000 mg ai/kg

- bw was determined from this study, indicating that sulfometuron methyl is categorized as practically non

- toxic (to xicity category IV) to small mammals on an acute oral basis. This study is considered acceptable and satisfies the guideline requirement (81

- 1) for an acute toxicity study with

mammals.

Formulated Product, Rat (Sprague Dawley)

. Formulated pesticide pro ducts may contain a number of other ‘inert’ ingredients that alter their toxicity compared to the technical grade active ingredient (e.g., resulting in greater toxicity). For sulfometuron methyl, data on the oral toxicity of formulated products were avail able for one species of terrestrial animal (rat). Results from this study indicate that the formulated product DPX

- T5486

- 87 (74% ai) is practically nontoxic to laboratory rats, with an LD50 of >5,000 mg ai/kg

- bw. No clinical signs of toxicity, weight los s or gross legions were observed in this study. This study satisfied guideline requirements for acute oral toxicity with rats and is considered acceptable.

Mammals, Chronic/Developmental

A combined 2

- generation reproduction /oncogenicity study and 2

- yea r chronic reproduction study with rats exposed to sulfometuron methyl was submitted to the agency (MRID 423857

- 05 and

423857

- 06). However, study authors had to abandoned the study on about day 200 due to disease of the test organisms that was not related to exposure. Portions of this study were submitted to the Agency (e.g., 90

- day and chronic reproduction) but were found unacceptable upon their review by HED. Similarly, a mammalian developmental toxicity study (MRID 78796) with the rat was also found to be invalid by HED.

A developmental toxicity study with the rabbit (Accession No. 78798 ) was submitted to the Agency. In this study, rabbits were administered doses of 0, 30, 100, or 300 mg/kg/day from gestation days (GD) 6

- 18 and examined at GD 29. The re were no mortalities and no treatment

related clinical signs or macroscopic findings. A slight decrease in maternal body weight occurred during the gestation period (GD 6

- 18) but this was judged biologically insignificant.

There were no treatment relat ed effects on fetal or maternal endpoints measured, including external, visceral or skeletal malformations, frequency of resorptions, live fetuses, or dead fetuses, or on the number of litters, sex ratio, or post

- implantation loss. The developmental

LOAEL was not observed. The developmental NOAEL is 300 mg/kg/day ( highest dose tested). According to the data evaluation record provided by HED, this study is acceptable but does not fulfill the guideline requirement for a developmental toxicity study with r abbits because dose levels were not considered high enough to adequately assess developmental toxicity.

Terrestrial Invertebrate

### 141 Honeybee, Apis mellifera. A honeybee acute contact study is required for sulfometuron methyl because its post

- emergence trea tment use will likely result in honeybee exposure. The acute

contact LD 50 

### , using the honey bee is a single

- dose laboratory study designed to estimate the quantity of toxicant required to cause 50% mortality in a test population of bees. For

sulfometuron m ethyl, bees were exposed at 5 treatments ranging from 13 to 100 μg ai/bee and included a solvent and negative control ( MRID 416728

- 10 ) . Results indicate that sulfometuron methyl is practically non

- toxic to bees on an acute contact basis. The contact 48

- h LD 50 

### for sulfometuron methyl is >100 μg ai/bee

. Cumulative mortality and immobility ranged from 4

- 8%

in the controls to 0

- 2% in the treatments. No overt signs of toxicity were observed in the study. The guideline (141

- 1) is fulfilled

.

Terrestrial Pla nts

For sulfometuron methyl, six dicots (sugar beet, rape, tomato, pea, cucumber and soybean) and four monocots (onion, corn, wheat, sorghum) were tested using the Tier 2 protocols for effects on seedling emergence an d vegetative vigor. Tier 1 tests were not conducted since preliminary testing indicated all plants would be promoted to Tier 2 testing. Test durations were 14 days and 21 days for the seedling emergence and vegetative vigor studies, respectively. Depend ing on the species and test, seven to eleven treatments were used with application rates ranged from 0.0000017 to 0.5625 lb ai/acre. For this risk assessment, a re

- review and statistical analysis was conducted on the Tier 2 toxicity data from the more sen sitive test species in both the seedling emergence and vegetative vigor tests. All statistical comparisons were made to negative controls (previous analyses in the DER made comparisons to solvent controls even though negative and

solvent controls were not significantly different). For calculation of the EC 25 

### and EC 05 

### , nonlinear regression was conducted using the methods of Bruce and Versteeg (1992). In situations where the NOAEC was found to be greater than or equal to the EC 25 

### , the EC 05 

### was used for the comparison with threatened and endangered species.

Results for the most sensitive endpoints and species with monocots and dicots indicate that seedling emergence and vegetative vigor are impacted at exposures well below the maximum application rate of 0 .375 lb ai/acre for sulfometuron methyl. For seedling emergence, the EC 25 

### of 1.9 x 10 - 4 

### lb ai/acre for the most sensitive monocot (sorghum) is about a factor of 5 greater

than the EC 25 

### of 3.2 x 10 - 5 

### lb ai/acre for the most sensitive dicot (sugar beet). For 9 of the 10 test species, a comparison of EC 25 

### values indicates that interspecies sensitivity differences are within a factor of 20 (based on summary data presented by McKelvey, 1995). This indicates that the most sensitive test species are not ‘outl iers’ in terms of their relative sensitivity. The EC 05 

### and NOAEC for the sorghum and sugar beet are 4.3 x 10 - 5 

### and 2.9 x 10 - 5 

### , respectively. A consistent, declining monotonic exposure

- response curve was observed for sugar beet, while that for sorghum was monotonic following an increase in mean shoot height of 24% in the lowest test treatment and 2% in the next lowest treatment relative to the negative control. Because the statistical method of Bruce and Versteeg (1992) uses a pooled response from the non

- monotonic portion of the dose

- response curve for calculating EC

x 

### values, the actual mean response

associated with the EC 05 

### for sorghum is slightly higher than the mean response observed for controls, rendering it a relatively conservative toxicological va lue.

### 142 Results from the vegetative vigor study indicate the most sensitive monocot (corn) and dicot (soybean) are impacted at somewhat lower levels compared to the seedling emergence study.

The EC 25 

### values for corn and soybean (shoot dry weight) are 3.7 x 10 - 5 

### and 1.8 x 10 - 5



### , respectively. Because the NOAEC exceeded the EC 25 

### values for both species, the EC 05 

### is used for risk assessment with threatened and endangered species. The EC 05 

### values for corn and soybean are 8.4 x 10 - 6 

### and 9.9 x 10 - 7 

### , respectivel y. For all 10 test species, a comparison of EC 25 

### values indicates that interspecies sensitivity differences are within a factor of 20 (based on summary data presented by McKelvey, 1995). This indicates that the most sensitive test species

are not ‘outlier s’ in terms of their relative sensitivity. A consistent, declining monotonic

exposure

- response curve was observed for corn and soybean in the vegetative vigor test.

II. Acceptable or Su pplemental Studies from ECOTOX

Aquatic Organisms

Naqvi and Hawkin s (1989). In this study, Naqvi and Hawkins (1989) exposed four genera of

field

- collected microcrustaceans ( Diaptomus sp. Eucyclops sp., Alonella sp., and Cypria sp. ) to sulfometuron methyl from the Oust ® 

### formulated product at nominal concentrations of ran ging from 100 to 2500 mg/L for 48

- h. Consistent, monotonic exposure

- response relationships across the six treatments occurred for all four species and 48

- h LC50s (probit analysis) were reported as

follows:

Species Test

Chemical 48

- h LC50 (mg/L) (95% confidence limits) Classification Reference

Diaptomus sp.

Oust ®

(~93% ai) 1315 (1207

- 1524) supplemental Naqvi and Hawkins (1989) Eucyclops sp. 1320 (1154

- 1536)

Alonella sp. 802 (475

- 928)

Cypria sp 2241 (1744

- 4517)



### This study is classified as supplemental primarily because test concentrations were not measured in the study and the field collec ted test organisms were provided a relatively short application period (96

- h) vs. the 7

- d minimum acclimation period recommend for freshwater inverteb rate testing. Furthermore, organisms were not positively identified to the species level, thus indicating that more than one test species may have been tested in each study. Finally, the study

authors do not indicate whether nominal concentrations were a djusted to reflect the percent active ingredient in the formulated product.

Romaire (1984). A study was submitted by the registrant (DuPont) per FIFRA Section 6(a)2 requirements on July 1, 1991. In this study, Romaire (1984) evaluated the acute toxicit y of

Oust ® 

### (% ai not reported) to juvenile red swamp crayfish, Procambarus clarkii . A static, acute toxicity study was conducted for 96 hours in 4 replicate aquaria (5 crayfish/aquarium) at 8 test concentrations ranging from 0 to 10,000 mg ai/L. Analytica l measurements sulfometuron methyl

### 143 were not taken during the study. The authors report that the 96

- h LC50 was > 5,000 mg ai/L for sulfometuron methyl and mortality did not exceed 50% in any test treatment. However, review of this study indicates that it is unacceptable because dissolved oxygen levels dropped precipitously throughout the study in test concentrations where mortality was observed, despite periodic aeration of test solutions. Dissolved oxygen levels repeatedly reached levels as low as 2.1 mg /L or approximately 25% saturation, which is well below ASTM recommendations of 60% saturation. Because the effect of dissolved oxygen on crayfish mortality could not be separated from the possible effects of sulfometuron methyl, this study is not conside red scientifically sound for the purposes of describing the acute toxicity of sulfometuron methyl to juvenile crayfish.

Byl et al. (1994)

. The effects of sulfometuron methyl on the aquatic vascular plant, Hydrilla
verticillata, were evaluated in a labor atory study conducted by Byl et al (1994). In this study

, Byl et al.) exposed plants to four aqueous solutions ranging from 0.001 to 1.0 mg/L sulfometuro n methyl (as the formulated product, Oust ® 

### , % ai not reported) . Three replicates were used per

treat ment and exposures continued for 5 days. The number of plants tested per replicate was not reported. A significant decrease in shoot length was observed at or above 0.01 mg/L, with combined shoot and root length approximating 30% of the controls. Reduct ion in mean growth followed a concentration dependent monotonic relationship. A significant increase in peroxidase activity (a potential biochemical indicator of chemical exposure) was also measured at 0.01 mg/L relative to controls. This study is classi fied as supplemental because sulfometuron methyl was not measured in the study and it is unclear whether results reported reflect % ai or total formulated product.

Fort et al (1999). In this study, Fort et al. (1999) conducted three separate tests of sul fometuron methyl exposure to the African clawed frog, Xenopus laevis : (1) a 4

- day frog embryo teratogenesis assay (FETAX ) to evaluate embryo mortality/ malformations; (2) a 14

- d test to evaluate effects on tail resporption, and (3) a 30

- d exposure to evalu ate effects on limb development. Both analytically impure (85% ai) and purified (99.5% ai) sulfometuron methyl exposures were evaluated in the study, but due to the confounding influence of impurities on sulfometuron methyl toxicity, results from only the purified (99.5% ai) sulfometuron methyl are

used here.

In the FETAX assay, 2 replicates of 20 mid

- blastula frog embryos (stage 8) were exposed to 11 nominal test concentrations of sulfometuron methyl ranging from 0.001 to 24.9 mg ai/L for 96

- h.

Sulfome turon methyl stock solutions were prepared using a DMSO carrier and verified analytically (analytical results not reported). Both a negative and solvent control were included. Test procedures generally conformed to ASTM recommendations for the FETAX assa y (ASTM, 1996). Results indicate no statistically significant effect of sulfometuron methyl on embryo survival or percent malformations up to (and including) the highest test concentration (24.9 mg/L). Solvent controls were not significantly different fr om negative controls.

Similar results were found in the 30

- d study, whereby no statistically significant effect of sulfometuron methyl exposure was found on limb development (% malformations) up through 24.9 mg/L. Results from the 14

- d tail resporption s tudy indicate a significant reduction in tail

### 144 resporption at 9.95 and 24.9 mg ai/L beginning at development stage 64 through 66 (test termination). No significant reduction occur at or below 1 mg ai/L.

This study is classified as supplemental primarily b ecause exposure concentrations were not measured during the test. Although the authors report that sulfometuron methyl was ‘stable’

over the 24 to 96

- h renewal cycles used in the studies, no analytical chemistry results were provided. Furthermore, random ization of study organisms and replicates was not indicated (an ASTM requirement). Collection and testing of embryos by separate clutches (an ASTM recommendation) was not apparent in the study. Finally, the final concentrations of carrier

solvent in the v arious treatments was not reported (solvent concentrations were only reported for the stock solutions).

Toxicity of sulfometuron methyl to the African clawed frog from a study by Fort et al. (1999).

Species Test

Chemical Exposure

Duration Endpoint (Ef fect) Effect

Level (mg ai/L) Study

Classification Ref.

Xenopus

laevis sulfometuron methyl (99.5% ai) 96

- h LC50 (% mortality) NOAEC (% malformations) > 24.9

24.9 (a) Supplemental Fort et al. (1999)

14

- d NOAEC (tail resorption) LOAEC (tail resporpt ion) 0.995

9.95

30

- d NOAEC (limb deformation) 24.9 (a)

(a) Highest tested dose, LOAEL not achieved in study.



### Terrestrial Organisms

Busse et al. (2005). In a greenhouse study, Busse et al. (2005) studied the effect of sulfometuron methyl (applied as the formulated product Oust) on ectomycorrhizal formation and seedling growth of three conifer species: ponderosa pine (Pinus ponderosa), Douglas fir (Pseudosuga menziesii), and white fir (Abies concolor). Conifer seedlings (5 replicates) were grown i n four different soil types and applied with sulfometuron methyl at 0, 1X and 2X its application rate of 0.14 kg ai/ha (0.125 lb/A). Sulfometuron methyl was applied to soil at the onset of lateral root formation (approximately 45

- 55 d post planting) due t o the high sensitivity of seedlings to sulfometuron methyl applied prior to this time period. Results indicate that ectomycorrhizal formation was not inhibited for any conifer regardless of soil type or application rate (1X or 2X). For ponderosa pine, see dling dry weight and root growth (number of root tips/plant) were significantly reduced relative to controls at 0.125 and 0.250 lb ai/A in two of the four soil types. For Douglas fir and white fir, no significant reduction in seedling dry weight occurred at any treatment level. However, root growth was reduced for Douglas fir at 0.125 lb ai/A for three of the four soil types and at 0.25 lb ai/A for the forth soil type. White fir appeared least sensitive to sulfometuron methyl, with significant reductions in root growth at 0.125 lb ai/A in one soil type and at 0.25 lb ai/A in a second soil type. The authors conclude that sulfometuron methyl does not inhibit mycorrhizal formation at the specified application rates but does inhibit plant growth of ponderosa pine and root growth of all three species, depending on soil type and application

### 145 rate. The lowest NOAEC from this study is 1X the application rate or 0.125 lb ai/A, several orders of magnitude above NOECs observed in the seedling emergence and vegetative vigor guideline studies.

Boyle and Walters (2005) examined the effect of saccharin, a major degradation product of sulfometuron methyl, on resistance of broad bean ( Vicia faba ) to rust fungus. Although not conceived as a degradate study per se, these re sults nevertheless have some relevance to the ecotoxicology of one of the sulfometuron methyl degradation products. In this study, 200 ml of 0.3 mM saccharin was applied either as a soil drench or to foliage of broad bean which were exposed to rust fungus four times over a 14

- d period. Results indicate that saccharin did not induce resistance to rust fungus nor did it significantly affect shoot weight or leaf area. However the authors report the number of leaflets formed was significantly reduced relativ e to controls.

Neary et al. (1984) evaluated the effects of sulfometuron methyl (as the formulated product Oust) on slash pine ( Pinus elliottii ) and loblolly pine ( Pinus taeda ) seedlings inhabiting coastal plain flatlands. In this study, 60 trees of eac h species were exposed to sulfometuron methyl via broadcast spray at 0.50 lb ai/A in a randomized factorial design involving different plot locations, irrigation and fertilization levels. Although this study was designed primarily to investigate the effic acy of different weed control methods, the authors did report that three months after treatment, application of sulfometuron methyl did not reduce survival of slash or loblolly pine, suggesting an unbounded NOAEC of 0.50 lb ai/A (only dose tested).

### 146 

## APP ENDIX I; ECOLOGICAL EFFECTS D ATA REQUIREMENTS

Ecological Effects Data Requirements for Sulfometuron Methyl

Guideline Data Requirement Test Material MRID Study

Classification Data Requirement

Met? More

Data

Needed?

71

- 1 Avian Oral LD 50 sulfom eturon methyl 245375 Acceptable Yes No

71

- 2 Avian Dietary LC 50 sulfometuron methyl 71414

246409 ( 2 ) Acceptable Acceptable Yes No

71

- 4 Avian Reproduction sulfometuron methyl Data Gap No Reserved (3 )

72

- 1 Freshwater Fish

LC 50 sulfometuron methy l 435018

- 0 1

435018

- 02 Acceptable Yes No

72

- 2 Freshwater

Invertebrate Acute

LC 50 sulfometuron methyl 435018

- 03 Acceptable (1) Yes No

72

- 3(a) Estuarine/Marine

Fish LC 50 sulfometuron methyl 416728

- 03 Supplemental

(1) No Reserved (3 )

72

- 3(b) Estuarine/ Marine

Mollusk EC 50 sulfometuron methyl 416728

- 05 Supplemental

(1) No Reserved (3 )

72

- 3(c) Estuarine/Marine Shrimp EC 50 sulfometuron methyl 416728

- 04 Supplemental

(1) No Reserved (3 )

72

- 4(a) Freshwater Fish Early Life

- Stage sulfometuron methyl 42385 7

- 04;

249796 (2) Invalid (1) No Reserved (3 )

72

- 4(b) Aquatic Invertebrate

Life

- Cycle (freshwater) sulfometuron methyl 416728

- 06 Acceptable Yes No

123

- 1(a) Seedling Emergence (Tier II) sulfometuron methyl 435385

- 01 Acceptable Yes No

123

- 1(b) Vegetativ e Vigor (Tier II) sulfometuron methyl 435385

- 01 Acceptable Yes No

### 147 Ecological Effects Data Requirements for Sulfometuron Methyl

Guideline Data Requirement Test Material MRID Study

Classification Data Requirement

Met? More

Data

Needed?

123

- 2 Aquatic

Plant

Growth Blue

- green Algae (Tier II) sulfometuron methyl 435385

- 02 Acceptable Yes No

Duckweed, Lemna gibba

(Tier II) sulfometuron methyl 435385

- 03 Acceptable Yes No

Freshwater Diatom,

Navicula (Tier 1) sulfometuron methyl 435385

- 02 Acceptable Yes No

Marine Diatom (Tier 1) sulfometuron methyl 435385

- 02 Acceptable Yes No

Green algae (Tier II) sulfometuron methyl 416801

- 02 Acceptable Yes No

141

- 1 Honey Bee Acu te
Contact LD 50 sulfometuron methyl 416728

- 10 Acceptable Yes No

(1) Study was re

- classified as part of this risk assessment.

(2) Accession number.

(3) Data requirement not met for this guideline study. However, risk assessment results are not likely to c hange based on submission of new acceptable data. Therefore, the data requirement for this study is reserved but may be required in the future should additional information warrant additional testing.

### 148 

## APPENDIX J : ECOLOGICAL EFFECTS S TUDIES REJECTED

BY OPP

SULFOMETURON METHYL + DEGRADATES Papers that Were Accepted for ECOTOX But Ultimately Rejected By OPP (May 2007)

Initial Screen Acceptable for ECOTOX and OPP

Ahrens, J. F. (1985). Evaluation of Sulfometuron Methyl for Weed Control in Christmas Tre e Plantings. Proc.Northeast.Weed Sci.Soc. 39: 249

- 253. ( Rejection Rationale: Target/efficacy study, Mixtures ; EcoReference No.: 31608)

Anderson, R. L., Lefever, F. R., and Maurer, J. K. (1988). The Effect of Various Saccharin

Forms on Gastro

- Intestinal Tract, Urine and Bladder of Male Rats. Food

Chem.Toxicol. 26: 665

- 669. ( Rejection Rationale: Endpoint Relevancy; EcoReference No.: 82947)

Byl, T. D. and Klaine, S. J. (1991). Peroxidase Activity as an Indicator of Sublethal Stress in the Aquatic Plant Hydrilla verticillata (Royle). In: J.W.Gorsuch, W.R.Lower, W.Wang, and M.A.Lewis (Eds.), Plants for Toxicity Assessment, 2nd Volume, ASTM STP 1115, Philadelphia, PA 101

- 106. ( Rejection Rationale: Superceded by Byl et al, 1994; EcoReference No.: 17181)

Cumberland, P. F. T., Richold, M., Parsons, J. F., and Pratten, M. K. (1994). Further Evaluation of a Teratogenicity Screen Using an Intravitelline Injection Technique. Toxicol. In

Vitro 8: 153

- 166. ( Rejection Rationale: Endpoint Relevancy, Exposure Rout e; EcoReference No.: 91195)

Dodel, J. B., Everaere, L., Gauthier, B., and Issaly, G. (1983). Use of Dpx 5648 Or Methyl 2

- (((((4,6

- Dimethyl

- 2

- Pyrimidinyl)Amino)

- Carbonyl)Amino)=Sulfonyl)Benzoate Or Dpx 5648, A New Herbicide for Weeding Uncultivated Plac. Columa 3: 257

- 265. ( Rejection Rationale: Target/Efficacy study; EcoReference No.: 31204)

Epelbaum, S., Landstein, D., Arad, S., Barak, Z., Chipman, D. M., Larossa, R. A., and Vandyk, T. K. (1992). Is the Inhibitory Effect of the Herbicide Sulfometuron Methyl due to 2 Ketobutyrate Accumulation? In: B.K.Singh, H.E.Flores, and J.C.Shannon (Eds.), 7th Annu. Penn. State Symp. in Plant Physiol., May 28

- 30, Univ.Park, PA, Am.Soc.of Plant Physiol., Rockville, MD 352

- 353. ( Rejection Rationale: Target/Efficacy study, Toxicity mechanisms);

Fleischer, S. J., Gaylor, M. J., Dickens, R., and Turner, D. L. (1989). Roadside Management of Annual Fleabane (Erigeron annuus) and Wild Carrot (Daucus carota). Weed Technol.

3: 72

- 75. ( Rejection Rationale: Target/Efficacy study; EcoReference No.: 90965) EcoReference No.: 49268)

### 149 Harada, K., Miyasaki, T., and Tamura, Y. (1994). Chemoattractant Effects of Sugars and Their Related Compounds on Black Abalone Haliotis discus. Comp.Biochem.Physiol.A

109: 111

- 115. ( Rejection Rati onale: Endpoint relevancy; EcoReference No.: 90554)

Hirose, M., Shirai, T., Tsuda, H., Fukushima, S., Ogiso, T., and Ito, N. (1981). Effect of Phenobarbital, Polychlorinated Biphenyl and Sodium Saccharin on Hepatic and Renal Carcinogenesis in Unilateral ly Nephrectomized Rats Given N

- Ethyl

- N

Hydroxyethylnitrosasmine Orally. Carcinogenesis 2: 1299

- 1302. ( Rejection

Rationale: Endpoint relevancy; EcoReference No.: 82213)

Kim, H.

- C., Cha, S.

- W., Ha, C.

- S., Roh, J.

- K., Lee, Y.

- S., Furukawa, F., Nishikawa, A., and Takahashi, M. (1996). Reappraisal of Eight Representative Carcinogenic and Non

Carcinogenic Compounds in a New Medium

- Term Rat Liver Bioassay Using.

Cancer Lett. 104: 85

- 90. ( Rejection Rationale: Endpoint relevancy; EcoReference No.: 90556)

Kin g, J. W. and Rogers III, J. N. (1986). Bermudagrass Growth Suppression with Sulfometuron Methyl and Metsulfuron Methyl. Ark Farm Re 35(2): 1

- 4. ( Rejection Rationale: Target/Efficacy study, Mixture; EcoReference No.: 31373)

Kitchin, K. T. and Ebron, M. T. (1983). Studies of Saccharin and Cyclohexylamine in a Coupled Microsomal activating/Embryo Culture System. Food Chem.Toxicol. 21: 537

- 541. ( Rejection Rationale: Endpoint relevancy; EcoReference No.: 90513)

Kramers, P. G. N. (1977). Mutagenicity of S accharin in Drosophila: The Possible Role of

Contaminants. Mutat.Res. 56: 163

- 167. ( Rejection Rationale: Endpoint relevancy; EcoReference No.: 90961)

Liscia, A., Masala, C., Crnjar, R., Sollai, G., and Solari, P. (2004). Saccharin Stimulates the

"Dete rrent" Cell in the Blowfly: Behavioral and Electrophysiological Evidence. Physiol.Behav. 80: 637

- 646. ( Rejection Rationale: Endpoint relevancy; EcoReference No.: 90053)

Nascimento, M. G., De Oliveira, M. L. C. S., Lima, A. S., and De Camargo, J. L. V. (2006). Effects of Diuron [3

- (3,4

- Dichlorophenyl)

- 1,1

- Dimethylurea] on the Urinary Bladder

of Male Wistar Rats . Toxicology 224: 66

- 73. ( Rejection Rationale: Endpoint relevancy; EcoReference No.: 90555)

Pszczolkowski, M. A. and Brown, J. J. (2003). Eff ect of Sugars and Non

- Nutritive Sugar Substitutes on Consumption of Apple Leaves by Codling Moth Neonates. Phytoparasitica 31: 283

- 291. ( Rejection Rationale: Target/Efficacy; EcoReference No.: 91055)

Sivan, A. and Arad, S. (1998). Intraspecific Transfe r of Herbicide Resistance in the Red Microalga Porphyridium sp. (Rhodophyceae) via Protoplast Fusion. J.Phycol. 34:

706

- 711. ( Rejection Rationale: Target/Efficacy; EcoReference No.: 61449)

### 150 Initial Screen Acceptable for ECOTOX but not OPP

Amin, S., Mo ore, R. W., Peterson, R. E., and Schantz, S. L. (2000). Gestational and Lactational Exposure to TCDD or Coplanar PCBs Alters Adult Expression of Saccharin

Preference Behavior in Female Rats. Neurotoxicol.Teratol. 22: 675

- 682.

EcoReference No.: 75076

Chem ical of Concern: TCDD,PCB,SAC; Habitat : T; Effect Codes : REP,GRO,BEH; Rejection Code : NO ENDPOINT(SAC)//PCBRES CODED,RQA,DATA,ENTERED,DONE.

2. Asamoto, M., Mann, A. M., and Cohen, S. M. (1994). P53 Mutation is Infrequent and Might not give a Growth Advantage in Rat Bladder Carcinogenesis In Vivo. Carcinogenesis 15: 455

- 458.

EcoReference No.: 90517 Chemical of Concern: SAC; Habitat : T; Effect Codes : CEL; Rejection Code : NO MIXTURE(SAC),NO COC(SMM).

3. Bannasch, P., Griesemer, R. A., Anders, F ., Becker, R., Cabral, J. R., Della Porta, G., Feron, V. J., Henschler, D., Ito, N., Kroes, R., Magee, P. N., McKnight, B., Montesano, R., Napalkov, N. P., Nesnow, S., Roberfroid, M., Slaga, T., Turusov, V. S., Wilbourn, J., and Williams, G. M. (1986). Ass ays for Initiating and Promoting Activities. In: R.Montesano, et al.(Eds.), IARC (Int.Agency for Res.on Cancer) Sci.Publ.No.83, Long

- Term and Short

- Term Assays for Carcinogens: A Critical Appraisal, Oxford
Univ.Press, New York, NY 103

- 126.

EcoReference N o.: 90967 Chemical of Concern: PbAC,EXQ,SAC,CTC; Habitat : T; Effect Codes : MOR,PHY; Rejection Code : NO CONTROL,ENDPOINT(SAC).

4. Bantle, J. A., Burton, D. T., Dawson, D. A., Dumont, J. N., Finch, R. A., Fort, D. J., Linder, G., and Rayburn, J. R. (1 994). Fetax Interlaboratory Validation Study: Phase II Testing. Environ.Toxicol.Chem. 13: 1629

- 1637.

EcoReference No.: 13502 Chemical of Concern: SMM; Habitat : A; Rejection Code : NO CONTROL(SMM).

5. Boswell, K. J., Reid, M. L., Fitch, J. V., Benne tt, S. M., Narciso, S. P., Hubbell, C. L., and Reid, L. D. (2005). Estradiol Valerate and Intake of Sweetened Water.

Pharmacol.Biochem.Behav. 80: 1

- 7.

EcoReference No.: 90545 Chemical of Concern: SAC; Habitat : T; Effect Codes : GRO,BEH; Rejection Code :

### 151 NO CONTROL,ENDPOINT(SAC).

6. Byl, T. D. and Klaine, S. J. (1991). Peroxidase Activity as an Indicator of Sublethal Stress in the Aquatic Plant Hydrilla verticillata (Royle). In: J.W.Gorsuch, W.R.Lower, W.Wang, and M.A.Lewis (Eds.), Plants for Toxicit y Assessment, 2nd Volume, ASTM STP 1115, Philadelphia, PA 101

- 106.

EcoReference No.: 17181 Chemical of Concern: SMM,CuS; Habitat : A; Effect Codes : BCM,GRO; Rejection

Code : LITE EVAL CODED(CuS),NO ENDPOINT(SMM).

7. Byl, T. D., Sutton, H. D., and Kla ine, S. J. (1994). Evaluation of Peroxidase as a Biochemical Indicator of Toxic Chemical Exposure in the Aquatic Plant Hydrilla verticillata, Royle. Environ.Toxicol.Chem. 13: 509

- 515.

EcoReference No.: 4016 Chemical of Concern: SMM,CuS,Se,Cd; Habitat : A; Effect Codes : BCM,GRO; Rejection Code : LITE EVAL CODED(CuS),NO ENDPOINT(SMM).

8. Cumberland, P. F. T., Richold, M., Parsons, J., and Pratten, M. K. (1994). Intravitelline Injection of Rodent Conceptuses: An Improved In Vitro Developmental Toxicity

Screen. Toxicol.In Vitro 8: 731

- 733.

EcoReference No.: 91267 Chemical of Concern: ETU,SAC; Habitat : T; Effect Codes : GRO,BCM,CEL; Rejection Code : NO CONTROL,NO ENDPOINT(ETU,SAC).

9. Duan, J. J. and Prokopy, R. J. (1993). Toward Developing Pestici de

- Treated Spheres for Controlling Apple Maggot Flies, Rhagoletis pomonella (Walsh) (Dipt., Tephritidae): I. Carbohydrates and Amino Acids as Feeding Stimulants. J.Appl.Entomol. 115: 176

- 184.

EcoReference No.: 91063 Chemical of Concern: SAC; Habitat : T ; Effect Codes : BEH; Rejection Code : NO CONTROL,ENDPOINT(SAC).

10. Fedtke, C., Schmalfuss, J., and Couderchet, M. (1999). Chloroacetanilides, Oxyacetamides, Tetrazolinones: Mode of Action. 1. Cross Resistance and Oleic Acid Incorporation in Algal M odel Systems. Pestic.Sci. 55: 580

- 582 .

EcoReference No.: 90964 Chemical of Concern: SMM,PCP,PAQT,DU,ACR,BTC,ATZ,BSF,CPP,MBZ;

Habitat : A; Effect Codes : POP; Rejection Code : NO CONTROL,ENDPOINT(SMM,PCP,ATZ).

11. Ferguson, S. A., Delclos, K. B., New bold, R. R., and Flynn, K. M. (2003). Dietary Ethinyl Estradiol Exposure During Development Causes Increased Voluntary Sodium

### 152 Intake and Mild Maternal and Offspring Toxicity in Rats. Neurotoxicol.Teratol. 25:

491

- 501.

EcoReference No.: 90547

Chemical of Concern: EED,SAC; Habitat : T; Effect Codes : GRO,BEH; Rejection

Code : NO ENDPOINT(SAC).

12. Ferguson, S. A., Flynn, K. M., Delclos, K. B., and Newbold, R. R. (2000). Maternal and Offspring Toxicity but few Sexually Dimorphic Behavioral Alterations Re sult from Nonylphenol Exposure. Neurotoxicol.Teratol. 22: 583

- 591.

EcoReference No.: 68835 Chemical of Concern: SAC,NYP; Habitat : T; Effect Codes : BEH,GRO,MOR,REP; Rejection Code : NO ENDPOINT(SAC).

13. Flynn, K. M., Ferguson, S. A., Delclos, K. B. , and Newbold, R. R. (2000). Effects of Genistein Exposure on Sexually Dimorphic Behaviors in Rats. Toxicol.Sci. 55: 311

- 319.

EcoReference No.: 90544 Chemical of Concern: SAC; Habitat : T; Effect Codes : GRO,BEH; Rejection Code : NO ENDPOINT(SAC).

14. Gonzalez, F. E., Atkins, R. L., and Brown, G. C. (1984). Sulfometuron Methyl, Rate and Timing Studies on Bermudagrass and Bahiagrass Roadside Turf. Proc.South Weed

Sci.Soc. 37: 272

- 274.

EcoReference No.: 31768 Chemical of Concern: SMM; Habitat : T; E ffect Codes : GRO; Rejection Code : NO ENDPOINT,NO CONTROL(TARGET

- SMM).

15. Hannan, P. J. (1995). A Novel Detection Scheme for Herbicidal Residues.

Environ.Toxicol.Chem. 14: 775

- 780.

EcoReference No.: 69628 Chemical of Concern: ATZ,PPZ,THF,CRME,TNM,AMT R,CZE,SMM; Habitat : AT; Effect Codes : PHY; Rejection Code : NO ENDPOINT(ALL CHEMS) .

16. Hartnett, M. E., Newcomb, J. R., and Hodson, R. C. (1987). Mutations in Chlamydomonas reinhardtii Conferring Resistance to the Herbicide Sulfometuron Methyl. Pl ant Physiol.(Bethesda) 85: 898

- 901.

EcoReference No.: 90536 Chemical of Concern: SMM; Habitat : A; Effect Codes : POP,PHY; Rejection Code : NO ENDPOINT(SMM).

### 153 17. Harvey, J. H. Jr., Dulka, J. J., and Anderson, J. J. (1985). Properties of Sulfometuron

M ethyl Affecting Its Environmental Fate: Aqueous Hydrolysis and Photolysis, Mobility and Adsorption on Soils, and Bioaccumulation Potential. J.Agric.Food

Chem. 33: 590

- 596.

EcoReference No.: 90543 Chemical of Concern: SMM; Habitat : A; Effect Codes : ACC; Rejection Code : NO ENDPOINT(SMM).

18. Hicks, R. M., Wakefield, J. S. J., and Chowaniec, J. (1975). Evaluation of a New Model to Detect Bladder Carcinogens or Co

- Carcinogens; Results Obtained with Saccharin, Cyclamate and Cyclophosphamide. Chem.

- Bi ol.Interact. 11: 225

- 233.

EcoReference No.: 91040 Chemical of Concern: SAC; Habitat : T; Effect Codes : PHY; Rejection Code : NO ENDPOINT(SAC).

19. Ikeda, M., Mitsui, T., Setani, K., Tamura, M., Kakeyama, M., Sone, H., Tohyama, C., and Tomita, T. (200 5). In Utero and Lactational Exposure to 2,3,7,8

- Tetrachlorodibenzo

- p

- Dioxin in Rats Disrupts Brain Sexual Differentiation. Toxicol.Appl.Pharmacol. 205: 98

- 105.

EcoReference No.: 80278 Chemical of Concern: TCDD,DXN,SAC; Habitat : T; Effect Codes : BEH, REP,GRO,BCM,PHY; Rejection Code : NO ENDPOINT(SAC)//PCBRES CODED,RQA,DATA ENTERED,DONE.

20. Ioannides, C., Lum, P. Y., and Parke, D. V. (1984). Cytochrome P

- 488 and the Activation of Toxic Chemicals and Carcinogens. Xenobiotica 14: 119

- 137 .

EcoReferen ce No.: 90546 Chemical of Concern: ETHN,SAC,DDT,AND; Habitat : T; Effect Codes : CEL,BCM; Rejection Code : NO ENDPOINT(SAC).

21. Jaffe, R. L. (1995). Rapid Assay of Cytotoxicity Using Tetramitus flagellates.

Toxicol.Ind.Health 11: 543

- 558.

EcoReferen ce No.: 5895 Chemical of Concern: Cd,SMM; Habitat : A; Rejection Code : NO ENDPOINT(SMM).

22. Koeppe, M. K. and Mucha, C. F. (1991). Metabolism of Sulfometuron Methyl in Lactating Goats. J.Agric.Food Chem. 39: 2304

- 2309.

EcoReference No.: 90542

Che mical of Concern: SMM; Habitat : T; Effect Codes : ACC; Rejection Code : NO CONTROL,ENDPOINT(SMM).

### 154 23. Kovar, J. L., Zhang, J., Funke, R. P., and Weeks, D. P. (2002). Molecular Analysis of the Acetolactate Synthase Gene of Chlamydomonas reinhardtii and Development of a Genetically Engineered Gene as a Dominant Selectable Marker for Genetic

Transformation. Plant J. 29: 109

- 117.

EcoReference No.: 90963 Chemical of Concern: SMM; Habitat : A; Effect Codes : CEL; Rejection Code : NO CONTROL(SMM).

24. K uhns, L. J. and Kaps, M. A. (1986). Sulfometuron Methyl and Imazapyr Applied as a Directed Spray on White Pine. Proc.Northeast.Weed Sci.Soc. 40: 263

- 264 .

EcoReference No.: 31014 Chemical of Concern: IZP,SMM,SMU; Habitat : T; Effect Codes : POP,PHY;

Re jection Code : NO ENDPOINT(ALL CHEMS,TARGET

- IZP,SMM,SMU).

25. Landstein, D., Arad, S., Barak, Z., and Chipman, D. M. (1993). Relationships Among the Herbicide and Functional Sites of Acetohydroxy Acid Synthase from Chlorella

emersonii. Planta 191: 1

- 6.

EcoReference No.: 91069 Chemical of Concern: SMM; Habitat : A; Effect Codes : BCM; Rejection Code : NO ENDPOINT(SMM).

26. Landstein, D., Epelbaum, S., Arad, S., Barak, Z., and Chipman, D. M. (1995). Metabolic Response of Chlorella emersonii to the Her bicide Sulfometuron Methyl. Planta 197:

219

- 224.

EcoReference No.: 90966 Chemical of Concern: SMM; Habitat : A; Effect Codes : BCM,PHY; Rejection

Code : NO ENDPOINT(TARGET

- SMM).

27. Langeland, K. A. (1986). Management Program for Alligatorweed in Nor th Carolina. Rep.No.224, Water Resour.Res.Inst.of the Univ.of N.Carolina 36 p.

EcoReference No.: 90590

Chemical of Concern:
MTPN,SMM,TPR,HXZ,BMC,AMTL,DU,IZP,DMB,FDE,GYP,24DXY; Habitat : AT; Effect Codes : POP; Rejection Code : NO CONTROL(SMM,HXZ,IZP,GY P),NO ENDPOINT(SMM,HXZ,BMC).

28. Lapidot, M., Raveh, D., Sivan, A., Arad, S., and Shapira, M. (2002). Stable Chloroplast Transformation of the Unicellular Red Alga Porphyridium Species. Plant Physiol.

129: 7

- 12.

### 155 EcoReference No.: 90535

Chemical of Conc ern: SMM; Habitat : A; Effect Codes : POP,PHY; Rejection Code : NO ENDPOINT(SMM).

29. Naqvi, S. M., Hawkins, R., and Naqvi, N. H. (1987). Mortality Response and LC50 Values for Juvenile and Adult Crayfish, Procambarus clarkii Exposed to Thiodan (Insect icide), Treflan, Msma, Oust. Environ.Pollut. 48: 275

- 283.

EcoReference No.: 12802 Chemical of Concern: SMM,TFN; Habitat : A; Effect Codes : MOR; Rejection

Code : NO CONTROL(SMM).

30. Nishida, N., Farmer, J. D., Kodavanti, P. R. S., Tilson, H. A., and MacPhail, R. C. (1997). Effects of Acute and Repeated Exposures to Aroclor 1254 in Adult Rats: Motor Activity and Flavor Aversion Conditioning. Fundam.Appl.Toxicol. 40: 68

- 74.

EcoReference No.: 90537 Chemical of Concern: SAC,PCB; Habitat : T; Effect Codes : GRO,BEH; Rejection

Code : NO CONTROL,ENDPOINT(SAC),OK(PCB).

31. Office of Pesticide Programs (2000). Pesticide Ecotoxicity Database (Formerly: Environmental Effects Database (EEDB)). Environmental Fate and Effects Division, U.S.EPA, Washington , D.C.

EcoReference No.: 344 Rejection Code : Secondary Duplicative Data

32. Peele, D. B., Farmer, J. D., and MacPhail, R. C. (1988). Behavioral Consequences of Chelator Administration in Acute Cadmium Toxicity. Fundam.Appl.Toxicol. 11:

416

- 428.

EcoR eference No.: 90538 Chemical of Concern: SAC,CdCl; Habitat : T; Effect Codes : GRO,BEH; Rejection

Code : NO ENDPOINT(SAC).

33. Roshon, R. D., McCann, J. H., Thompson, D. G., and Stephenson, G. R. (1999). Effects of Seven Forestry Management Herbicides on Myriophyllum sibiricum, as Compared with Other Nontarget Aquatic Organisms. Can.J.For.Res. 29: 1158

- 1169.

EcoReference No.: 60978 Chemical of Concern: 24DXY,GYP,HXZ,IZP,MSFM,SMM,TPR; Habitat : A;

Effect Codes : GRO,MOR; Rejection Code : NO CONTROL(A LL CHEMS),TARGET SMM.

34. Schiffman, S. S., Suggs, M. S., Donia, M. B. A., Erickson, R. P., and Nagle, H. T. (1995). Environmental Pollutants Alter Taste Responses in the Gerbil.

Pharmacol.Biochem.Behav. 52: 189

- 194.

### 156 EcoReference No.: 74836

Chemical of Concern: CBF,PYT,MTM,ACP,CPY,DEM,MLN,CBL,FNV,PAQT,GYP,SMM ; Habitat : T;

Effect Codes : PHY; Rejection Code : NO ENDPOINT(ALL CHEMS).

35. Van

- Moppes, D., Barak, Z., Chipman, D. M., Gollop, N., and Arad, S. (1989). An Herbicide (Sulfometuron Methyl) Re sistant Mutant in Porphyridium (Rhodophyta). J.Phycol. 25: 108

- 112.

EcoReference No.: 90533 Chemical of Concern: SMM; Habitat : A; Effect Codes : POP,PHY; Rejection Code : NO ENDPOINT(SMM)