**UNITED STATES ENVIRONMENTAL PROTECTION
AGENCY**![](media/image1.wmf){width="1.1256944444444446in"
height="1.0618055555555554in"}

**WASHINGTON, D.C. 20460**

**OFFICE OF**

**PREVENTION, PESTICIDES**

**AND TOXIC SUBSTANCES**

**Environmental Fate and Ecological Risk Assessment**

**for the Reregistration of Sulfometuron-methyl: Vegetative Management
and Other Non-crop Uses**

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

+-------------------------------------+-------------------------------+---+
| ![](media/image                     |                               |   |
| 2.wmf){width="3.6034722222222224in" |                               |   |
| height="2.0944444444444446in"}      |                               |   |
|                                     |                               |   |
| **SULFOMETURON METHYL**             |                               |   |
|                                     |                               |   |
| **PC Code: 122001; CAS Number:      |                               |   |
| 74222-97-2**                        |                               |   |
+-------------------------------------+-------------------------------+---+
| **Note: Appendix A has been         | **February 14, 2008**         |   |
| slightly revised from the 11/28/07  |                               |   |
| review (DP Barcode D346171) per     | **DP Barcode D334277**        |   |
| registrant comment.**               |                               |   |
|                                     | **United States Environmental |   |
| **Prepared by:**                    | Protection Agency**           |   |
|                                     |                               |   |
| **M. Barrett, Chemist,**            | **Office of Pesticide         |   |
|                                     | Programs**                    |   |
| **Environmental Fate Reviewer, ERB  |                               |   |
| V**                                 | **Environmental Fate and      |   |
|                                     | Effects Division**            |   |
| **K. Sappington, Biologist,**       |                               |   |
|                                     | **Environmental Risk Branch   |   |
| **Ecological Effects Reviewer, ERB  | V**                           |   |
| V**                                 |                               |   |
|                                     | **1200 Pennsylvania Ave.**    |   |
| **Approved by:**                    |                               |   |
|                                     | **Mail Code 7507P**           |   |
| **Mah Shamim, PhD, Chief ERB V**    |                               |   |
|                                     | **Washington, D.C. 20460**    |   |
+-------------------------------------+-------------------------------+---+

**TABLE OF CONTENTS**

### [1. EXECUTIVE SUMMARY 8](#executive-summary) {#executive-summary-8 .TOC-1}

[1.1. Nature of Chemical Stressor 8](#nature-of-chemical-stressor)

[1.2. Conclusions- Exposure Characterization
8](#conclusions--exposure-characterization)

[1.3. Conclusions- Effects Characterization
9](#conclusions--effects-characterization)

[1.4. Potential Risks to Non-target Animals and Plants
10](#potential-risks-to-non-target-animals-and-plants)

[1.5. Conclusions - Endangered Species
11](#conclusions---endangered-species)

[1.6. Identification of Uncertainties and Their Impact on the Risk
Assessment
13](#identification-of-uncertainties-and-their-impact-on-the-risk-assessment)

[1.6.1. Environmental Fate and Exposure
13](#environmental-fate-and-exposure)

[1.6.2. Ecological Effects 14](#ecological-effects)

### [2. PROBLEM FORMULATION 15](#problem-formulation) {#problem-formulation-15 .TOC-1}

[2.1. Nature of the Regulatory Action
15](#nature-of-the-regulatory-action)

[2.2. Stressor Source and Distribution
15](#stressor-source-and-distribution)

[2.2.1. Nature of the Chemical Stressor
15](#nature-of-the-chemical-stressor)

[2.2.2. Overview of Pesticide Usage 17](#overview-of-pesticide-usage)

[2.3. Receptors 17](#receptors)

[2.3.1. Aquatic and Terrestrial Effects
17](#aquatic-and-terrestrial-effects)

[2.3.2. Ecosystems at Risk 19](#ecosystems-at-risk)

[2.4. Assessment Endpoints 19](#assessment-endpoints)

[2.5. Conceptual Model 20](#conceptual-model)

[2.5.1. Risk Hypotheses 20](#risk-hypotheses)

[2.5.2. Conceptual Diagram 20](#conceptual-diagram)

[2.6. Analysis Plan 24](#__RefHeading___Toc191187526)

[2.6.1. Conclusions from Previous Risk Assessments
24](#conclusions-from-previous-risk-assessments)

[2.6.2. Preliminary Identification of Data Gaps and Analysis Plan
25](#preliminary-identification-of-data-gaps-and-analysis-plan)

[2.6.3. Measures of Effect and Exposure
25](#measures-of-effect-and-exposure)

### [3. ANALYSIS 27](#analysis) {#analysis-27 .TOC-1}

[3.1. USE CHARACTERIZATION 27](#use-characterization)

[3.2. EXPOSURE CHARACTERIZATION 33](#exposure-characterization)

[3.2.1. Environmental Fate and Transport Characterization
33](#environmental-fate-and-transport-characterization)

[3.2.2. Measures of Aquatic Exposure 43](#measures-of-aquatic-exposure)

[3.2.2.1. Aquatic Exposure Monitoring and Field Data
43](#aquatic-exposure-monitoring-and-field-data)

[3.2.2.2. Aquatic Exposure Modeling 43](#aquatic-exposure-modeling)

[3.2.3. Measures of Terrestrial Exposure
51](#measures-of-terrestrial-exposure)

[3.2.3.1. Terrestrial Exposure Modeling
51](#terrestrial-exposure-modeling)

[3.2.3.2. Residue Studies 56](#residue-studies)

[3.2.4. Uncertainties and Limitations for this Exposure Assessment
56](#uncertainties-and-limitations-for-this-exposure-assessment)

[3.2.4.1. Limitations In Knowledge Of Actual Use Patterns
56](#limitations-in-knowledge-of-actual-use-patterns)

[3.2.4.2. Variability In Sulfometuron Environmental Persistence
57](#variability-in-sulfometuron-environmental-persistence)

[3.2.4.3. Exposure To Sulfometuron Methyl Degradates
57](#exposure-to-sulfometuron-methyl-degradates)

[3.3. ECOLOGICAL EFFECTS CHARACTERIZATION
57](#ecological-effects-characterization)

[3.3.1. Aquatic Effects Characterization
59](#aquatic-effects-characterization)

[3.3.1.1. Freshwater Fish, Acute 59](#freshwater-fish-acute)

[3.3.1.2. Freshwater Invertebrates, Acute
60](#freshwater-invertebrates-acute)

[3.3.1.3. Estuarine and marine Fish, Acute
60](#estuarine-and-marine-fish-acute)

[3.3.1.4. Estuarine and marine Invertebrates, Acute
61](#estuarine-and-marine-invertebrates-acute)

[3.3.1.5. Freshwater Fish, Chronic 62](#freshwater-fish-chronic)

[3.3.1.6. Freshwater Invertebrate, Chronic
62](#freshwater-invertebrate-chronic)

[3.3.1.7. Aquatic Animal Sublethal Effects: Formulated Product and
Degradate Toxicity
63](#aquatic-animal-sublethal-effects-formulated-product-and-degradate-toxicity)

[3.3.1.8. Field Studies 64](#field-studies)

[3.3.1.9. Aquatic Plants 65](#aquatic-plants)

[3.3.2. Terrestrial Effects Characterization
66](#terrestrial-effects-characterization)

[3.3.2.1. Acute Effects on Birds 66](#acute-effects-on-birds)

[3.3.2.2. Acute Effects on Mammals 67](#acute-effects-on-mammals)

[3.3.2.3. Acute Effects on Terrestrial-phase Amphibians, Reptiles and
Beneficial Insects
68](#acute-effects-on-terrestrial-phase-amphibians-reptiles-and-beneficial-insects)

[3.3.2.4. Chronic Effects on Birds 68](#chronic-effects-on-birds)

[3.3.2.5. Mammals, Reproductive Effects
69](#mammals-reproductive-effects)

[3.3.2.6. Terrestrial Animal Sublethal Effects, Formulated Product and
Degradation Products
69](#terrestrial-animal-sublethal-effects-formulated-product-and-degradation-products)

[3.3.2.7. Field Studies 70](#field-studies-1)

[3.3.2.8. Terrestrial Plants 70](#terrestrial-plants)

### [4. RISK CHARACTERIZATION 73](#risk-characterization) {#risk-characterization-73 .TOC-1}

[4.1. Risk Estimation - Integration of Exposure and Effects Data
73](#risk-estimation---integration-of-exposure-and-effects-data)

[4.1.1. Non-target Aquatic Animals and Plants
75](#non-target-aquatic-animals-and-plants)

[4.1.1.1. Fish and Aquatic Invertebrates
75](#fish-and-aquatic-invertebrates)

[4.1.1.2. Aquatic Plants 76](#aquatic-plants-1)

[4.1.2. Non-target Terrestrial Animals
77](#non-target-terrestrial-animals)

[4.1.2.1. Birds, Acute Risks 77](#birds-acute-risks)

[4.1.2.2. Birds, Chronic Risks 78](#birds-chronic-risks)

[4.1.2.3. Mammals, Acute Risks 78](#mammals-acute-risks)

[4.1.2.4. Mammals, Chronic Risks 79](#mammals-chronic-risks)

[4.1.2.5. Non-Target Terrestrial-phase Amphibians, Reptiles and
Terrestrial Invertebrates
80](#non-target-terrestrial-phase-amphibians-reptiles-and-terrestrial-invertebrates)

[4.1.3. Non-target Terrestrial Plants
81](#non-target-terrestrial-plants)

[4.1.3.1. Non-Endangered and Endangered Plant Risks
81](#non-endangered-and-endangered-plant-risks)

[4.1.4. Use of Contaminated Irrigation Waters
82](#use-of-contaminated-irrigation-waters)

[4.2. RISK DESCRIPTION 83](#risk-description)

[4.2.1. Risk to Aquatic Animals and Plants
83](#risk-to-aquatic-animals-and-plants)

[4.2.1.1. Fish and Aquatic Invertebrates
83](#fish-and-aquatic-invertebrates-1)

[4.2.1.2. Non-target Aquatic-phase Amphibians
85](#non-target-aquatic-phase-amphibians)

[4.2.1.3. Aquatic Plants 86](#aquatic-plants-2)

[4.2.1.4. Aquatic Toxicity of Sulfometuron Methyl Degradates
87](#aquatic-toxicity-of-sulfometuron-methyl-degradates)

[4.2.2. Risk to Terrestrial Animals 90](#risk-to-terrestrial-animals)

[4.2.2.1. Birds 90](#birds)

[4.2.2.2. Mammals 92](#mammals)

[4.2.2.3. Non-target Terrestrial-phase Amphibians, Reptiles, and
Beneficial Insects
92](#non-target-terrestrial-phase-amphibians-reptiles-and-beneficial-insects)

[4.2.3. Risk to Terrestrial Plants 92](#risk-to-terrestrial-plants)

[4.2.3.1. Tier 1 Modeling of Runoff and Spray Drift
92](#tier-1-modeling-of-runoff-and-spray-drift)

[4.2.3.2. Field and Greenhouse Studies
93](#field-and-greenhouse-studies)

[4.2.3.3. Contaminated Irrigation Water
94](#contaminated-irrigation-water)

[4.2.4. Refined Spray Drift Analysis 95](#refined-spray-drift-analysis)

[4.2.5. Review of Incident Data 97](#review-of-incident-data)

[4.2.6. Overall Ecological Risk Conclusions
98](#overall-ecological-risk-conclusions)

[4.2.7. Endocrine Effects 99](#endocrine-effects)

[4.2.8. Federally Threatened and Endangered (Listed) Species
99](#federally-threatened-and-endangered-listed-species)

[4.2.8.1. Action Area 99](#action-area)

[4.2.8.2. Taxonomic Groups Potentially at Risk
100](#taxonomic-groups-potentially-at-risk)

[4.3. Description of Assumptions, Limitations, Uncertainties, and Data
Gaps
105](#description-of-assumptions-limitations-uncertainties-and-data-gaps)

[4.3.1. Assumptions and Limitations Related to Effects on all Species
105](#assumptions-and-limitations-related-to-effects-on-all-species)

[4.3.2. Assumptions and Limitations Related to Effects on Aquatic
Species
107](#assumptions-and-limitations-related-to-effects-on-aquatic-species)

[4.3.3. Assumptions and Limitations Related to Effects on Terrestrial
Species
107](#assumptions-and-limitations-related-to-effects-on-terrestrial-species)

### [5. Literature Cited 108](#literature-cited) {#literature-cited-108 .TOC-1}

### [6. APPENDICES 111](#appendices) {#appendices-111 .TOC-1}

### [APPENDIX A: Structures and Chemical Names of Sulfometuron methyl Metabolites 111](#appendix-a-structures-and-chemical-names-of-sulfometuron-methyl-metabolites) {#appendix-a-structures-and-chemical-names-of-sulfometuron-methyl-metabolites-111 .TOC-1}

### [APPENDIX B: Environmental Fate Data Requirements 113](#appendix-b-environmental-fate-data-requirements) {#appendix-b-environmental-fate-data-requirements-113 .TOC-1}

### [APPENDIX C: Ecological Aquatic Exposure Modeling 115](#appendix-c-ecological-aquatic-exposure-modeling) {#appendix-c-ecological-aquatic-exposure-modeling-115 .TOC-1}

### [APPENDIX D: Terrplant Spreadsheet 123](#appendix-d-terrplant-spreadsheet) {#appendix-d-terrplant-spreadsheet-123 .TOC-1}

### [APPENDIX E: Adverse Ecological Incidents Associated with Sulfometuron Methyl Use 125](#appendix-e-adverse-ecological-incidents-associated-with-sulfometuron-methyl-use) {#appendix-e-adverse-ecological-incidents-associated-with-sulfometuron-methyl-use-125 .TOC-1}

### [APPENDIX F: T-REX Output 127](#appendix-f-t-rex-output) {#appendix-f-t-rex-output-127 .TOC-1}

### [APPENDIX G: Modeling of Terrestrial plant Exposure from Contaminated irrigation Water 129](#appendix-g-modeling-of-terrestrial-plant-exposure-from-contaminated-irrigation-water) {#appendix-g-modeling-of-terrestrial-plant-exposure-from-contaminated-irrigation-water-129 .TOC-1}

### [APPENDIX H: Ecological Effects Data Summaries 131](#appendix-h-ecological-effects-data-summaries) {#appendix-h-ecological-effects-data-summaries-131 .TOC-1}

### [APPENDIX I; Ecological Effects Data Requirements 144](#appendix-i-ecological-effects-data-requirements) {#appendix-i-ecological-effects-data-requirements-144 .TOC-1}

### [APPENDIX J: Ecological Effects Studies Rejected by OPP 146](#appendix-j-ecological-effects-studies-rejected-by-opp) {#appendix-j-ecological-effects-studies-rejected-by-opp-146 .TOC-1}

**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](#__RefHeading___Toc191187615)

[Table 2. Nature and product chemistry of the chemical stressor -
Sulfometuron methyl. 15](#__RefHeading___Toc191187616)

[Table 3. Taxonomic Groups, Test Species and Acute Toxicity
Classification for Assessing Ecological Risks of Sulfometuron Methyl to
Non-target Organisms. 18](#__RefHeading___Toc191187617)

[Table 4. Measures of Ecological Effects and Exposure for Sulfometuron
Methyl 26](#__RefHeading___Toc191187618)

[Table 5. Permitted application methods for sulfometuron methyl, DuPont
Products 28](#__RefHeading___Toc191187619)

[Table 6. Permitted application methods for sulfometuron methyl,
Vegetation Management LLC Products 28](#__RefHeading___Toc191187620)

[Table 7. States with high sulfometuron usage (based upon DuPont sales
data, 2001-2004). 28](#__RefHeading___Toc191187621)

[Table 8. Annual usage of sulfometuron methyl in the US by use site.
29](#__RefHeading___Toc191187622)

[Table 9. Sulfometuron application rate ranges by product label and use
site. 30](#__RefHeading___Toc191187623)

[Table 10. Key results of sulfometuron methyl environmental fates
studies. 35](#__RefHeading___Toc191187624)

[Table 11. Models Used to Estimate Exposure Concentrations for Aquatic
Ecosystem. 44](#__RefHeading___Toc191187625)

[Table 12. Aquatic exposure with PRZM -- EXAMS: Modeling scenarios and
representative usage pattern summary. 45](#__RefHeading___Toc191187626)

[Table 13. PRZM/EXAMS input parameters for modeling (Aquatic ecological
EECs). 46](#__RefHeading___Toc191187627)

[Table 14. Estimated environmental concentrations (µg/L) for aquatic
exposure to parent sulfometuron methyl: scenario-specific results from
PRZM-EXAMS modeling. 48](#__RefHeading___Toc191187628)

[Table 15. Sulfometuron methyl surface water EECs used in aquatic risk
assessment. 50](#__RefHeading___Toc191187629)

[Table 16. Estimated concentrations of sulfometuron methyl in ground
water (SCI-GROW inputs and results). 50](#__RefHeading___Toc191187630)

[Table 17. Unadjusted Dietary Terrestrial EECs for Birds and Mammals
Following Sulfometuron Methyl Spray Application For Non-Crop Vegetative
Management. 52](#__RefHeading___Toc191187631)

[Table 18. EECs for Terrestrial Plants Located Adjacent to Sulfometuron
Methyl (aerial and ground spray application) Treated Sites.
53](#__RefHeading___Toc191187632)

[Table 19. Selected AgDRIFT inputs for high-end exposure from aerial
applications of sulfometuron methyl using best management practices.
54](#__RefHeading___Toc191187633)

[Table 20. Estimated percentage of sulfometuron methyl spray drift from
ground or aerial applications at various distances from a treated field.
55](#__RefHeading___Toc191187634)

[Table 21. Estimated amount of sulfometuron methyl spray drift from
ground or aerial applications at various distances from a field treated
with the maximum labeled rate of 0.375 lb ai/A.
56](#__RefHeading___Toc191187635)

[Table 22. The Most Sensitive Endpoints Used In The Sulfometuron Methyl
Screening-Level Risk Estimation. 59](#__RefHeading___Toc191187636)

[Table 23. Freshwater Fish Acute Toxicity of Sulfometuron Methyl.
60](#__RefHeading___Toc191187637)

[Table 24. Freshwater Invertebrate Acute Toxicity of Sulfometuron
Methyl. 60](#__RefHeading___Toc191187638)

[Table 25. Estuarine/Marine Fish Acute Toxicity of Sulfometuron Methyl.
61](#__RefHeading___Toc191187639)

[Table 26. Freshwater Invertebrate Acute Toxicity of Sulfometuron
Methyl. 62](#__RefHeading___Toc191187640)

[Table 27. Freshwater Aquatic Invertebrate Chronic Toxicity for
Sulfometuron Methyl. 63](#__RefHeading___Toc191187641)

[Table 28. Non-target Aquatic Plant Toxicity for Sulfometuron Methyl.
66](#__RefHeading___Toc191187642)

[Table 29. Avian Acute Oral Toxicity for Sulfometuron Methyl.
67](#__RefHeading___Toc191187643)

[Table 30. Avian Subacute Dietary Studies for Sulfometuron Methyl.
67](#__RefHeading___Toc191187644)

[Table 31. Mammalian Acute Toxicity for Sulfometuron Methyl.
68](#__RefHeading___Toc191187645)

[Table 32. Non-Target Insects - Acute Contact Toxicity for Sulfometuron
Methyl. 68](#__RefHeading___Toc191187646)

[Table 33. Mammalian Developmental Toxicity of Sulfometuron Methyl .
69](#__RefHeading___Toc191187647)

[Table 34. Mammalian Acute Toxicity to Sulfometuron Methyl in Formulated
Product: DPX-T5486-87 70](#__RefHeading___Toc191187648)

[Table 35. Summary of Most Sensitive Tier II Terrestrial Non-target
Plant Seedling Emergence and Vegetative Vigor Toxicity Data for
Sulfometuron Methyl. 72](#__RefHeading___Toc191187649)

[Table 36. Risk Presumptions for Aquatic Animals.
74](#__RefHeading___Toc191187650)

[Table 37. Risk Presumptions for Terrestrial Animals.
74](#__RefHeading___Toc191187651)

[Table 38. Risk Presumptions for Plants.
74](#__RefHeading___Toc191187652)

[Table 39. Endpoints Used for Estimating Risks of Sulfometuron Methyl to
Aquatic Animals and Plants. 75](#__RefHeading___Toc191187653)

[Table 40. Summary of Acute Aquatic Plant Risk Quotients for Rights of
Way Uses. 76](#__RefHeading___Toc191187654)

[Table 41. Endpoints Used for Estimating Risks of Sulfometuron Methyl to
Terrestrial Animals. 77](#__RefHeading___Toc191187655)

[Table 42. Upper Bound Kenaga, Acute Avian Dose-Based Risk Quotients
(Bounding Analysis Only). 78](#__RefHeading___Toc191187656)

[Table 43. Upper Bound Kenaga, Subacute Dietary-Based Risk Quotients
(Bounding Analysis Only). 78](#__RefHeading___Toc191187657)

[Table 44. Upper Bound Kenaga, Acute Mammalian Dose-Based Risk Quotients
(Bounding Analysis Only). 79](#__RefHeading___Toc191187658)

[Table 45. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk
Quotients. 79](#__RefHeading___Toc191187659)

[Table 46. Upper Bound Kenaga, Chronic Mammalian Dietary-Based Risk
Quotients 80](#__RefHeading___Toc191187660)

[Table 47. Summary of Selected Endpoints from Terrestrial Plant Toxicity
Studies of Sulfometuron Methyl 81](#__RefHeading___Toc191187661)

[Table 48. RQ Values For Plants In Dry And Semi-Aquatic Areas Exposed To
Sulfometuron Methyl Through Runoff And/Or Spray Drift.
81](#__RefHeading___Toc191187662)

[Table 49. Risk Quotients for Non-target and Endangered Plants,
Resulting From Exposure to Sulfometuron Methyl in Irrigation Water
82](#__RefHeading___Toc191187663)

[Table 50. Toxicity of sulfometuron methyl to the African clawed frog
from a study by Fort et al. (1999). 86](#__RefHeading___Toc191187664)

[Table 51. ECOSAR-predicted toxicity values for major degradates of
sulfometuron methyl. 88](#__RefHeading___Toc191187665)

[Table 52. Risks to Terrestrial Plants from Spray Drift According to
Distance Downwind, Application Method, and Drift Exposure Conditions
95](#__RefHeading___Toc191187666)

[Table 53. Listed Taxonomic Groups Potentially at Risk from Direct or
Indirect Effects of Sulfometuron Methyl Application for Vegetative
Management Throughout the U.S. 104](#__RefHeading___Toc191187667)

**LIST OF FIGURES**

[Figure 1. Conceptual model for sulfometuron methyl fate and effects in
aquatic ecosystems. 22](#_Ref177952507)

[Figure 2. Conceptual model for sulfometuron methyl fate and effects in
terrestrial ecosystems. 23](#_Ref177952990)

[Figure 3. Chronic Toxicity of Sulfonylurea Herbicides to Freshwater
Fish 84](#__RefHeading___Toc191187670)

[Figure 4. Chronic Avian Toxicity of Sulfonylurea Herbicides
91](#__RefHeading___Toc191187671)

# EXECUTIVE SUMMARY {#executive-summary .Style-Heading-1-+-Left}

## Nature of Chemical Stressor

Sulfometuron methyl, (2-\[\[\[\[(4,6-Dimethyl-2-pyrimidinyl) amino\]
carbonyl\] amino\] sulfonyl\] benzoic acid, methyl ester), is a
broad-spectrum pre- and post-emergence herbicide that is currently
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 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. It is
generally applied once per year for non-crop areas in years that
vegetation 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 ai/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 species. 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.

## 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 sulfometuron is likely to
be lowest under low pH conditions in soil and water.

Abiotic and microbially-mediated hydrolysis / degradation are both major
routes of transformation of sulfometuron methyl in water, soil, and
water-sediment systems. The degradation in soil and water appears to be
enhanced in the presence of an active microbial population (aerobic and
anaerobic degradation both proceed more slowly under sterile
conditions).

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.

Sulfometuron methyl does not sorb strongly to soils and has the
potential to leach to ground 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.

## Conclusions- Effects Characterization 

Available acute toxicity data for freshwater fish and invertebrates
indicate that sulfometuron 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 exposure
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 estimated
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 is 97 mg ai/L (highest
concentration tested) at which survival and reproduction were 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 saltwater species acute toxicity values
does not suggest considerable differences in sensitivity between
freshwater and saltwater species.

Aquatic vascular plants are more sensitive than any of the aquatic
nonvascular plants tested. The 14-day EC~50~ and NOAEC for 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, respectively, 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 observed 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 exposure 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).

Seedling emergence and vegetative vigor studies in terrestrial plants
were submitted by the registrant. Based on the most sensitive species
and endpoints reported, sulfometuron methyl is slightly more toxic to
terrestrial plants in the vegetative vigor study compared to seedling
emergence. The seedling emergence EC25 for the most sensitive dicot
(sugar 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 emergence and vegetative
vigor studies reported non-lethal effects of sulfometuron methyl
exposure on plants such as chlorosis, growth retardation, necrosis, and
unusual pigmentation.

## Potential Risks to Non-target Animals and Plants

Potential risks to aquatic 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 drift
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 risks 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 values 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/EXAMS 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 conditions modeled.

Although use 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 risks 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-driven 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.

An analysis 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 substantial 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, reduces the downwind
drift 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 recommended, 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
regularly, sulfometuron methyl concentrations in surface irrigation
water may result in damage to agricultural crops that are sensitive to
sulfometuron methyl.

## Conclusions - 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 taxonomic 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 level, 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 (AgDRIFT; 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 endangered
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 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. 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
altered (i.e. reduced bird populations in edge 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 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 vegetative management uses nationwide.

[]{#__RefHeading___Toc191187615 .anchor}Table 1. Listed Taxonomic Groups
Potentially at Risk from Direct or Indirect Effects of Sulfometuron
Methyl Application for Vegetative Management Throughout the U.S.

  --------------------------------------------------------------------------------------------
  **Listed Taxon**    **Direct    **Basis for Direct    **Indirect   **Basis for Indirect
                      Effects**   Effects Concern**     Effects**    Effects Concern**
  ------------------- ----------- --------------------- ------------ -------------------------
  Terrestrial and     Yes         The endangered and    Yes          Potential concerns from
  Semi-Aquatic Plants             non-endangered                     shifts in plant community
  -- monocots and                 species LOCs are                   structure and function
  dicots                          exceeded for                       due to from selective
                                  terrestrial plants.                impacts on plant species.

  Terrestrial         No          Sulfometuron methyl   Yes          Potential concerns for
  Invertebrates                   is practically                     terrestrial invertebrates
                                  nontoxic to                        that use plants for
                                  honeybees, suggesting              habitat, feeding, or
                                  no direct effect                   cover requirements.
                                  concerns for                       
                                  terrestrial                        
                                  invertebrates.                     

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

  Terrestrial-phase   No          The LOC is not        Yes          Potential concerns for
  Amphibians^(1)^                 exceeded                           terrestrial-phase
                                                                     amphibians that use
                                                                     plants for habitat,
                                                                     feeding, or cover
                                                                     requirements.

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

  Aquatic Vascular    Yes         The endangered and    Yes          Potential concerns from
  Plants and                      non-endangered                     shifts in plant community
  Nonvascular Plants              species LOCs are                   structure and function
                                  exceeded for aquatic               due to from selective
                                  vascular and                       impacts on plant species.
                                  nonvascular plants.                

  Freshwater and      No          The LOC is not        Yes          Potential concerns for
  Marine/Estuarine                exceeded                           fish and aquatic-phase
  fish and                                                           amphibians that use
  Aquatic-phase                                                      plants for habitat,
  Amphibians^(2)^                                                    feeding, or cover
                                                                     requirements.

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

  Mollusks            No          The LOC is not        Yes          Potential concerns for
                                  exceeded                           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 fish and
aquatic-phase amphibian species are considered equivalent.

## Identification of Uncertainties and Their Impact on the Risk Assessment

### Environmental Fate and Exposure

**Limitations In Knowledge Of Actual Use Patterns**

-   Specific regions of use are not known. 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 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 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)

**Variability In Sulfometuron Environmental Persistence**

-   Sulfometuron methyl persistence is significantly affected by soil or
    water chemistry and may not always be 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 / sediments with a greater range of pH
    levels 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 Sulfometuron 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 constrains
    the modeling. The data on individual degradates, environmental
    persistence and mobility is insufficient to model each compound
    separately. Furthermore, total residue modeling with the currently
    available receiving water body assumes residues concentrate in that
    body (pond) since:

    -   available data require assumptions of total stability of
        sulfometuron total residues (because insufficient decline data
        are available from the laboratory studies);

    -   The existing surface water exposure scenario assumes these
        stable residues do not migrate from the pond and simply
        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 terrestrial 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.

### Ecological Effects

-   **Indirect Effects to Animals.** In this screening-level risk
    assessment, 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 exposure 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 quantify the indirect effects 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 effects 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, sulfonamide) 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 application of the total residue
    approach in the exposure assessment. Second, acceptable ecotoxicity
    data were 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 Data 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 including
    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 orders 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 emergence 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 vegetative growth
    or visual injury (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.

# PROBLEM FORMULATION {#problem-formulation .Style-Heading-1-+-Left}

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 provides a plan for analyzing the data and characterizing
the risk (US EPA, 1998).

## 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 methyl. 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.

## Stressor Source and Distribution 

### Nature of the Chemical Stressor 

Sulfometuron methyl, a broad-spectrum pre- and post-emergence herbicide,
is currently registered for weed control in forestry and non-food crop
situations, including vegetative management in rights-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.
A brief summary of the product chemistry data on sulfometuron methyl is
provided in Table 2.

+----------------------+-----------------------------------------------+
| []{#__RefHe          |                                               |
| ading___Toc191187616 |                                               |
| .anchor}Table 2.     |                                               |
| Nature and product   |                                               |
| chemistry of the     |                                               |
| chemical stressor -  |                                               |
| Sulfometuron methyl. |                                               |
+----------------------+-----------------------------------------------+
| **Common name**      | Sulfometuron methyl                           |
+----------------------+-----------------------------------------------+
| **IUPAC Chemical     | 2-(                                           |
| Name**               | 4,6-Dimethylpyrimidin-2-ylcarbamoylsulfamoyl) |
|                      | benzoic acid, methyl ester                    |
|                      |                                               |
|                      | ***OR***                                      |
|                      |                                               |
|                      | > 2-\[3                                       |
|                      | -(4,6-dimethylpyrimidin-2-yl)ureidosulfonyl\] |
|                      | > benzoic acid, methyl ester                  |
+----------------------+-----------------------------------------------+
| **CAS Chemical       | 2-\[\[\[\[(4,6-Dimethyl-2-pyrimidinyl)        |
| Name**               | amino\] carbonyl\]                            |
|                      |                                               |
|                      | amino\] sulfonyl\] benzoic acid, methyl ester |
+----------------------+-----------------------------------------------+
| **Structure**        | > ![](m                                       |
|                      | edia/image2.wmf){width="2.5104166666666665in" |
|                      | > height="1.457638888888889in"}               |
+----------------------+-----------------------------------------------+
| **Pesticide type**   | Herbicide                                     |
+----------------------+-----------------------------------------------+
| **Chemical class**   | Sulfonylurea herbicide                        |
+----------------------+-----------------------------------------------+
| **CAS number**       | 74222-97-2                                    |
+----------------------+-----------------------------------------------+
| **Empirical          | C~15~H~16~N~4~SO~5~                           |
| formula**            |                                               |
+----------------------+-----------------------------------------------+
| **Molecular Mass     | 364.38                                        |
| (g/mol)**            |                                               |
+----------------------+-----------------------------------------------+
| **Vapor pressure at  | 5.4 x10^-16^ Torr                             |
| 20^o^ C**            |                                               |
+----------------------+-----------------------------------------------+
| **Henry's Law        | 1.1 x 10^-18^, calculated                     |
| Constant at 20^o^    |                                               |
| C**                  | from vapor pressure                           |
|                      |                                               |
| **(atm m3/mol)**     |                                               |
+----------------------+-----------------------------------------------+
| **Solubility in      | pH 5 buffer\...\... 6.42 ppm                  |
| water (mg/L)at       |                                               |
| 20^0^C**             | pH 7 buffer \...\... 244 ppm                  |
|                      |                                               |
|                      | pH 8.6 buffer.. 12,500 ppm                    |
+----------------------+-----------------------------------------------+
| **Log K~ow~**        | pH 5 = 1.03                                   |
|                      |                                               |
|                      | pH 7 = -0.46                                  |
|                      |                                               |
|                      | pH 9 = -1.87                                  |
+----------------------+-----------------------------------------------+
| **pKa at 25°C**      | 5.2                                           |
+----------------------+-----------------------------------------------+

Sulfometuron methyl may be persistent and mobile and may have 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 degradation / mineralization is more rapid under
aerobic conditions and is generally enhanced substantially when microbes
are present. The primary route of degradation is by the following
pathway involving cleavage of the sulfonylurea bridge:

(1) Hydrolytic cleavage generating a sulfonamide plus the
    aminopyrimidine (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.

Sulfometuron methyl is considered "mobile" according 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
concentrations 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.

### Overview of Pesticide Usage

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.
Sulfometuron methyl is registered for non-crop agricultural and
vegetative management uses throughout the United States. The 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 substations), 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.

## Receptors

### 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 potentially 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. Toxicological data generated from
surrogate test species, that are intended to be representative of broad
taxonomic groups, are used to extrapolate to potential effects on a
variety of species (receptors) included under these taxonomic groupings.

Acute and chronic toxicity data from studies submitted by pesticide
registrants along with the available open literature are used to
evaluate potential direct effects 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 functional characteristics
of the affected communities.

Table 3 provides 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,
sulfometuron 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 highest 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 reproductive toxicity data were not
available for birds or mammals**.** As expected, aquatic and terrestrial
plants show the greatest sensitivity to the parent compound.

[]{.mark}

Major environmental degradates of sulfometuron methyl most commonly
include: the sulfometuron sulfonamide, the sulfometuron pyrimidine
amine, and saccharin; other degradates occur less commonly (see Table 10
and APPENDIX A: Structures and Chemical Names of Sulfometuron methyl
Metabolites). 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 substantially phytotoxic,
however, information is requested from the registrant to confirm this.

[]{#__RefHeading___Toc191187617 .anchor}Table 3. Taxonomic Groups, Test
Species and Acute Toxicity Classification for Assessing Ecological Risks
of Sulfometuron Methyl to Non-target Organisms.

+------------------+---------------------------+-----------------------+
| **Taxonomic      | **Example(s) of Surrogate | **Acute Toxicity      |
| Group**          | Species**                 | Classification**      |
+==================+===========================+=======================+
| Birds^1^         | Mallard duck (*Anas       | Practically non-toxic |
|                  | platyrhynchos*)           |                       |
|                  |                           |                       |
|                  | Bobwhite quail (*Colinus  |                       |
|                  | virginianus*)             |                       |
+------------------+---------------------------+-----------------------+
| Mammals          | Laboratory rat (*Rattus   | Practically non-toxic |
|                  | norvegicus*)              |                       |
+------------------+---------------------------+-----------------------+
| Insects          | Honey bee (*Apis          | Practically non-toxic |
|                  | mellifera L.*)            |                       |
+------------------+---------------------------+-----------------------+
| Freshwater       | Bluegill sunfish          | Practically non-toxic |
| fish^2^          | (*Lepomis macrochirus*)   |                       |
|                  |                           | Practically non-toxic |
|                  | Rainbow trout             |                       |
|                  | (*Oncorhynchus mykiss*)   |                       |
+------------------+---------------------------+-----------------------+
| Freshwater       | Water flea (*Daphnia      | Practically non-toxic |
| invertebrates    | magna*)                   |                       |
+------------------+---------------------------+-----------------------+
| Estuarine/marine | Sheepshead minnow         | [\>]{.underline}      |
| fish             | *(Cyprinodon variegatus)* | Slightly toxic^4^     |
+------------------+---------------------------+-----------------------+
| Estuarine/marine | Mysid shrimp *(Mysidopsis | [\>]{.underline}      |
| invertebrates    | bahia)*                   | Slightly toxic^4^     |
|                  |                           |                       |
|                  | Eastern oyster            | [\>]{.underline}      |
|                  | (*Crassostrea virginica)* | Slightly toxic^4^     |
+------------------+---------------------------+-----------------------+
| Terrestrial      | Monocots -- corn (*Zea    | Not classified        |
| plants^3^        | mays*)                    |                       |
|                  |                           |                       |
|                  | Dicots -- soybean         |                       |
|                  | (*Glycine max*)           |                       |
+------------------+---------------------------+-----------------------+
| Aquatic plants   | Duckweed (*Lemna gibba*)  | Not classified        |
| and algae        |                           |                       |
|                  | Green algae (*Selenastrum |                       |
|                  | capricornutum*)           |                       |
|                  |                           |                       |
|                  | Bluegreen algae           |                       |
|                  | (*Anabaena flos-aquae)*   |                       |
|                  |                           |                       |
|                  | Diatom (*Navicula         |                       |
|                  | pelliculosa)*             |                       |
+------------------+---------------------------+-----------------------+

^1^ In absence of data, birds are used as surrogates for
terrestrial-phase amphibians and reptiles.

^2^ In absence of data, freshwater fish may be surrogates for
aquatic-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.

### 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. As a result, it is not possible
to identify 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 drift 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 toxicity data indicate terrestrial plants are
highly sensitive to sulfometuron methyl and thus, they could be directly
affected. Organisms dependent on sensitive terrestrial plants could be
affected indirectly, which could result in subsequent effects at the
community and ecosystem levels. 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 habitat.

Aquatic ecosystems potentially at risk include water bodies adjacent to,
or down stream from, the treatment area and might include impounded
bodies such as ponds, lakes, reservoirs 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 and 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 indirectly to the
extent they depend on affected plants for food and habitat.

## 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 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).

## Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological
receptors in biologically significant concentrations. An exposure
pathway is the means by which a pesticide moves in the environment from
a source to an ecological receptor. For an ecological pathway to be
complete, it must have a source, a release mechanism, an environmental
transport medium, a point of exposure for ecological receptors, and a
feasible route of exposure.

A conceptual model is used in this risk assessment to provide a written
and visual description 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,
1998).

### 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 sulfometuron 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
> organisms will be exposed when sulfometuron 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.*

### Conceptual Diagram

Based on the iterative process of examining the usage information, fate
and effects data, the risk hypotheses described previously, conceptual
diagrams 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) the organisms that are
most relevant and applicable to this assessment.

The dominant sources/transport pathways of sulfometuron methyl to
[aquatic ecosystems]{.underline} 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 due to modeling 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 water and sediments
may also 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]{.underline} 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. Volatilization 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 items,
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 ground water or surface water sources. Indirect impacts may
occur on animals that depend on affected terrestrial plants for food or
habitat.

[]{#_Ref177952507 .anchor}

Figure 1. Conceptual model for sulfometuron methyl fate and effects 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
quantitatively.

[]{#_Ref177952990 .anchor}

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

^1^ Solid 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
quantitatively.

## Analysis Plan 

This document characterizes the environmental fate and effects of
sulfometuron 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 data
evaluation review (DER) to determine their 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 studies 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 literature 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 Guidelines (See
<http://www.epa.gov/oppefed1/ecorisk_ders/toera_analysis_exp.htm#WSAN2>
and
<http://www.oecd.org/department/0,3355,en_2649_34377_1_1_1_1_1,00.html>
).

### Conclusions from Previous Risk Assessments

No previous environmental fate and ecological risk assessment was
available for sulfometuron methyl that was comparable to current OPP
practices. 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 assessments 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 assessment (USDA,
2004) indicate that risk of direct toxicity 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 plants (peak concentrations) and up to 15,000 for
terrestrial plants based on the NOAEC for vegetative vigor. The US
Forest Service assessment considered only ground 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 spray, drift, or
surface runoff of sulfometuron methyl were identified for terrestrial
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 plants from surface runoff to 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.

### Preliminary 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 and 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 freshwater 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 growth 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 Study (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 environmental fate data gaps.

[In accordance with OPP practices for conducting baseline ecological
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 effect. A commonly used measure of
exposure is the estimated exposure concentration (EEC) and commonly used
measures of effect include toxicity values such as the]{.mark} LD~50~
[or NOAEC.]{.mark} The resulting RQ is then compared to a specified LOC.
If the RQ exceeds an LOC, then risks are identified.

### 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 selected for this baseline risk assessment.

+-----------+---------------+---------------------+------------------+
| []{#      |               |                     |                  |
| __RefHead |               |                     |                  |
| ing___Toc |               |                     |                  |
| 191187618 |               |                     |                  |
| .anc      |               |                     |                  |
| hor}Table |               |                     |                  |
| 4.        |               |                     |                  |
| Measures  |               |                     |                  |
| of        |               |                     |                  |
| E         |               |                     |                  |
| cological |               |                     |                  |
| Effects   |               |                     |                  |
| and       |               |                     |                  |
| Exposure  |               |                     |                  |
| for       |               |                     |                  |
| Sul       |               |                     |                  |
| fometuron |               |                     |                  |
| Methyl    |               |                     |                  |
+===========+===============+=====================+==================+
| **A       |               | **Surrogate Species | **Measures of    |
| ssessment |               | and Measures of     | Exposure**       |
| E         |               | Ecological          |                  |
| ndpoint** |               | Effect^1^**         |                  |
+-----------+---------------+---------------------+------------------+
| Birds^2^  | Survival      | Bobwhite acute oral | Maximum residues |
|           |               | LD~50~              | on food items    |
|           |               |                     | (foliar)         |
|           |               | Bobwhite and        |                  |
|           |               | mallard subacute    |                  |
|           |               | dietary LC~50~      |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Bobwhite and        |                  |
|           | and growth    | mallard chronic     |                  |
|           |               | reproduction NOAEC  |                  |
|           |               | and LOAEC           |                  |
|           |               |                     |                  |
|           |               | **(no studies       |                  |
|           |               | available)**        |                  |
+-----------+---------------+---------------------+------------------+
| Mammals   | Survival      | Laboratory rat      |                  |
|           |               | acute oral LD~50~   |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Laboratory rat oral |                  |
|           | and growth    | reproduction        |                  |
|           |               | chronic NOAEC and   |                  |
|           |               | LOAEC               |                  |
|           |               |                     |                  |
|           |               | **(no acceptable    |                  |
|           |               | studies             |                  |
|           |               | available)**        |                  |
+-----------+---------------+---------------------+------------------+
| F         | Survival      | Rainbow trout and   | Peak EEC^4^      |
| reshwater |               | bluegill sunfish    |                  |
| fish^3^   |               | acute LC~50~        |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Fathead minnow      | 60-day average   |
|           | and growth    |                     | EEC^4^           |
|           |               | chronic (early      |                  |
|           |               | life-stage) NOAEC   |                  |
|           |               | and LOAEC           |                  |
|           |               |                     |                  |
|           |               | **(no acceptable    |                  |
|           |               | studies             |                  |
|           |               | available)**        |                  |
+-----------+---------------+---------------------+------------------+
| F         | Survival      | Water flea acute    | Peak EEC^4^      |
| reshwater |               | EC~50~              |                  |
| inve      |               |                     |                  |
| rtebrates |               |                     |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Water flea chronic  | 21-day average   |
|           | and growth    | (life cycle) LOAEC  | EEC^4^           |
+-----------+---------------+---------------------+------------------+
| Estuari   | Survival      | Sheepshead minnow   | Peak EEC^4^      |
| ne/marine |               | acute LC~50~        |                  |
| fish      |               |                     |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Sheepshead minnow   | 60-day average   |
|           | and growth    | chronic (early      | EEC^4^           |
|           |               | life-stage) NOAEC   |                  |
|           |               | and LOAEC           |                  |
|           |               |                     |                  |
|           |               | **(No studies       |                  |
|           |               | available)**        |                  |
+-----------+---------------+---------------------+------------------+
| Estuari   | Survival      | Eastern oyster      | Peak EEC^4^      |
| ne/marine |               | acute EC~50~ and    |                  |
| inve      |               | mysid acute LC~50~  |                  |
| rtebrates |               |                     |                  |
+-----------+---------------+---------------------+------------------+
|           | Reproduction  | Mysid chronic NOAEC | 21-day average   |
|           | and growth    | and LOAEC           | EEC^4^           |
|           |               |                     |                  |
|           |               | **(no data          |                  |
|           |               | available)**        |                  |
+-----------+---------------+---------------------+------------------+
| Te        | Survival and  | Monocot and dicot   | Estimates of     |
| rrestrial | growth        | seedling emergence  | runoff and spray |
| plants^5^ |               | and vegetative      | drift to         |
|           |               | vigor EC~25,~       | non-target areas |
|           |               | EC~05~, and NOAEC   |                  |
|           |               | values              |                  |
+-----------+---------------+---------------------+------------------+
| Insects   | Survival (not | Honeybee acute      | Maximum          |
|           | q             | contact LD~50~      | application rate |
|           | uantitatively |                     |                  |
|           | assessed)     |                     |                  |
+-----------+---------------+---------------------+------------------+
| Aquatic   | Survival and  | Algal and vascular  | Peak EEC         |
| plants    | growth        | plant (i.e.,        |                  |
| and algae |               | duckweed) EC~50~    |                  |
|           |               | and NOAEC values    |                  |
|           |               | for growth rate and |                  |
|           |               | biomass             |                  |
|           |               | measurements        |                  |
+-----------+---------------+---------------------+------------------+

^1^ Species listed in this table represent most commonly encountered
species from registrant-submitted studies, risk assessment guidance
indicates most sensitive 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 10-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 concentration; 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.

# 

# ANALYSIS  {#analysis .Style-Heading-1-+-Left}

## 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. is 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 management (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 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***[^1] ***of
active ingredient per year*.** 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 species.
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. Ranges of
application rates by use are summarized in Table 9.

Considering all types of uses, regions 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
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 ingredient Table 8.

  --------------------------------- ---------------------------------------------------------
  []{#__RefHeading___Toc191187619   
  .anchor}Table 5. Permitted        
  application methods for           
  sulfometuron methyl, DuPont       
  Products                          

  Forestry/ Plantations             Aerial (fixed wing, helicopter), ground (closed cab), and
                                    backpack (spot spray).

  Vegetative Management             Aerial (helicopter) and ground (closed and open cab).

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

  --------------------------------- ---------------------------------------------------------
  []{#__RefHeading___Toc191187620   
  .anchor}Table 6. Permitted        
  application methods for           
  sulfometuron methyl, Vegetation   
  Management LLC Products           

  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 (forestry applications
                                    include banded or spot hand applications).
  --------------------------------- ---------------------------------------------------------

  --------------------------------- -------------- -------------- -------------- --------------
  []{#__RefHeading___Toc191187621                                                
  .anchor}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**    **10 to 20**   **\> 20**

  Forestry                          OR, TX, LA,    AR, MS, AL     \-\--          \-\--
                                    GA, VA                                       

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

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

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

[]{#__RefHeading___Toc191187622 .anchor}Table 8. Annual usage of
sulfometuron methyl in the US by use site.

+-------------------------------------------------+---------+----------+
|                                                 |         |          |
+-------------------------------------------------+---------+----------+
| ***Use Site***                                  | ***Low  | ***High  |
|                                                 | Es      | E        |
|                                                 | tim.*** | stim.*** |
+-------------------------------------------------+---------+----------+
|                                                 | *       |          |
|                                                 | *Annual |          |
|                                                 | U       |          |
|                                                 | sage,** |          |
|                                                 |         |          |
|                                                 | **Lbs   |          |
|                                                 | ai**    |          |
+-------------------------------------------------+---------+----------+
| (Commercial Christmas Trees - Nurseries)        | 50      | 830      |
+-------------------------------------------------+---------+----------+
| Forestry                                        | 89,000  | 100,000  |
+-------------------------------------------------+---------+----------+
| Non-crop Vegetative Management (VM - includes   | 80,000  | 100,000  |
| Roadway, Utility & Pipeline)                    |         |          |
+-------------------------------------------------+---------+----------+
| Railroad (RR)                                   | 50,000  | 71,000   |
+-------------------------------------------------+---------+----------+
| Total                                           | 230,000 | 261,000  |
+-------------------------------------------------+---------+----------+
| Estimates reflect ranges from combined          |         |          |
| registrant and OPP-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. |         |          |
+-------------------------------------------------+---------+----------+

[]{#__RefHeading___Toc191187623 .anchor}Table 9. Sulfometuron
application rate ranges by product label and use site.

+---------------+--------+---------+--------+-----------+------------+
| **Product     | **Type | **Add   | **Use  | **Single  | **Single   |
| Name**        | of     | itional | Sit    | App. Low  | App. High  |
|               | F      | Active  | e(s)** | Rate      | Rate       |
|               | ormula | I       |        | (pounds   | (pounds    |
|               | tion** | ngredie |        | a.i.)**   | a.i.)**    |
|               |        | nt(s)** |        |           |            |
+===============+========+=========+========+===========+============+
| DuPont™ Oust® | Dispe  | None    | Fo     | 0.047     | 0.375      |
|               | rsible | (may be | restry |           |            |
| Herbicide     | gr     | tank    |        | 0.047     | 0.375      |
|               | anules | mixed)  | No     |           |            |
| Or            |        |         | n-Crop |           |            |
| "Sulfometuron |        |         |        |           |            |
| methyl 75"    |        |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™ Oust® | Dispe  | None    | Fo     | 0.023     | 0.375      |
| XP Herbicide  | rsible | (may be | restry |           |            |
|               | gr     | tank    |        | 0.047     | 0.375      |
|               | anules | mixed)  | No     |           |            |
|               |        |         | n-Crop |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Mets    | C      | 0.023     | 0.281      |
|               | rsible | ulfuron | onifer |           |            |
| Oust® Extra   | gr     | Methyl  | Plant  | 0.016     | 0.188      |
| Herbicide     | anules |         | ations |           |            |
|               |        |         |        |           |            |
|               |        |         | No     |           |            |
|               |        |         | n-Crop |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Hex     | Fo     | 0.075     | 0.175      |
| Oustar®       | rsible | azinone | restry |           |            |
|               | gr     |         |        |           |            |
| Herbicide     | anules |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Hex     | Chr    | 0.025     | 0.100      |
| Westar®       | rsible | azinone | istmas |           |            |
|               | gr     |         | Trees  | 0.100     | 0.131      |
| Herbicide     | anules |         |        |           |            |
|               |        |         | Fo     | 0.131     | 0.194      |
|               |        |         | restry |           |            |
|               |        |         |        |           |            |
|               |        |         | No     |           |            |
|               |        |         | n-Crop |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Chlors  | No     | 0.023     | 0.281      |
| Landmark® MP  | rsible | ulfuron | n-Crop |           |            |
| Herbicide     | gr     |         |        |           |            |
|               | anules |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Chlors  | No     | 0.035     | 0.350      |
| Landmark® II  | rsible | ulfuron | n-Crop |           |            |
| MP Herbicide  | gr     |         |        |           |            |
|               | anules |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Chlors  | No     | 0.023     | 0.281      |
| Landmark® XP  | rsible | ulfuron | n-Crop |           |            |
| Herbicide     | gr     |         |        |           |            |
|               | anules |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Chlors  | No     | 0.035     | 0.350      |
| Landmark® II  | rsible | ulfuron | n-Crop |           |            |
| XP Herbicide  | gr     |         |        |           |            |
|               | anules |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Sulfen  | No     | 0.141     | 0.141      |
|               | rsible | trazone | n-Crop |           |            |
| Throttle™ MP  | gr     |         | \*\*   |           |            |
| Herbicide     | anules | Chlors  |        |           |            |
|               |        | ulfuron |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| DuPont™       | Dispe  | Sulfen  | No     | 0.141     | 0.141      |
|               | rsible | trazone | n-Crop |           |            |
| Throttle™ XP  | gr     |         |        |           |            |
|               | anules | Chlors  |        |           |            |
| Herbicide     |        | ulfuron |        |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | C      | 0.063     | 0.250      |
| Extra         | rsible | tank    | onifer |           |            |
|               | gr     | mixes   | Site   |           |            |
|               | anules |         | Prepa  |           |            |
|               |        |         | ration |           |            |
|               |        |         | (pre-  |           |            |
|               |        |         | plant) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | C      | 0.125     | 0.188      |
| Extra         | rsible | tank    | onifer |           |            |
|               | gr     | mixes   | R      |           |            |
|               | anules |         | elease |           |            |
|               |        |         | (post  |           |            |
|               |        |         | -trans |           |            |
|               |        |         | plant) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | C      | 0.281     | 0.375      |
| Extra         | rsible | tank    | onifer |           |            |
|               | gr     | mixes   | Site   |           |            |
|               | anules |         | Prepa  |           |            |
|               |        |         | ration |           |            |
|               |        |         | or     |           |            |
|               |        |         | Pos    |           |            |
|               |        |         | t-tran |           |            |
|               |        |         | splant |           |            |
|               |        |         | for    |           |            |
|               |        |         | sp     |           |            |
|               |        |         | ecific |           |            |
|               |        |         | weeds  |           |            |
|               |        |         | (e.g., |           |            |
|               |        |         | Kudzu) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | Har    | 0.023     | 0.234      |
| Extra         | rsible | tank    | dwoods |           |            |
|               | gr     | mixes   | (see   |           |            |
|               | anules |         | dlings |           |            |
|               |        |         | or     |           |            |
|               |        |         | trans  |           |            |
|               |        |         | plants |           |            |
|               |        |         | in     |           |            |
|               |        |         | dor    |           |            |
|               |        |         | mancy) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | Non    | 0.035     | 0.375      |
| Extra         | rsible | tank    | -Crop: |           |            |
|               | gr     | mixes   |        |           |            |
|               | anules |         | "N     |           |            |
|               |        |         | on-Agr |           |            |
|               |        |         | icultu |           |            |
|               |        |         | ral"\* |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | Non    | 0.188     | 0.375      |
| Extra         | rsible | tank    | -Crop: |           |            |
|               | gr     | mixes   |        |           |            |
|               | anules |         | Under  |           |            |
|               |        |         | a      |           |            |
|               |        |         | sphalt |           |            |
|               |        |         | and    |           |            |
|               |        |         | co     |           |            |
|               |        |         | ncrete |           |            |
|               |        |         | pav    |           |            |
|               |        |         | ements |           |            |
|               |        |         | (      |           |            |
|               |        |         | before |           |            |
|               |        |         | p      |           |            |
|               |        |         | aving) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| SFM 75, SFM   | Dispe  | Only in | Non    | 0.023     | 0.188      |
| Extra         | rsible | tank    | -crop: |           |            |
|               | gr     | mixes   |        |           |            |
|               | anules |         | Turf   |           |            |
|               |        |         | (unimp |           |            |
|               |        |         | roved) |           |            |
+---------------+--------+---------+--------+-----------+------------+
| \*\* Non-Crop |        |         |        |           |            |
| lumps         |        |         |        |           |            |
| together uses |        |         |        |           |            |
| such as       |        |         |        |           |            |
| r             |        |         |        |           |            |
| ights-of-way, |        |         |        |           |            |
| industrial    |        |         |        |           |            |
| site weed     |        |         |        |           |            |
| management,   |        |         |        |           |            |
| applications  |        |         |        |           |            |
| 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.       |        |         |        |           |            |
+---------------+--------+---------+--------+-----------+------------+

## EXPOSURE CHARACTERIZATION

### 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 potentially dominant under acidic
conditions. First-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 comparison, 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 entire ca. 350 to
500 days of each study)[^3]. 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 of 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 17 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 with 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 trend 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
percent.

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 soils where the methyl ester form of
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 sulfometuron-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(OM) -- 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 percent 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 sulfonylureas 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 terrestrial field dissipation studies at four US sites, leaching of
parent sulfometuron methyl occurred 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 levels (but possibly still high enough to be
phytotoxic) of sulfometuron methyl residues were 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 a several year period should limit the
actual exposure of sulfometuron methyl parent residues in surface water
(however, note that sulfometuron 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 surface water estimated environmental concentration
(EEC) of 31.5 µg/L; additional assumptions for this modeling are
discussed in "Section 3.2.2.2, Aquatic Exposure Modeling". 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. However, 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 occurs 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 "APPENDIX 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 characteristics of two of the
sulfometuron methyl degradates were studied 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). This 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)

+------------+------------------------------------------------+--------+
| [          |                                                |        |
| ]{#__RefHe |                                                |        |
| ading___To |                                                |        |
| c191187624 |                                                |        |
| .an        |                                                |        |
| chor}Table |                                                |        |
| 10. Key    |                                                |        |
| results of |                                                |        |
| su         |                                                |        |
| lfometuron |                                                |        |
| methyl     |                                                |        |
| env        |                                                |        |
| ironmental |                                                |        |
| fates      |                                                |        |
| studies.   |                                                |        |
+============+================================================+========+
| ***Pa      | ***Value^1^***                                 | *      |
| rameter*** |                                                | **MRID |
|            |                                                | (s)*** |
| ***\       |                                                |        |
| [Guideline |                                                |        |
| #\]***     |                                                |        |
+------------+------------------------------------------------+--------+
| Hydrolysis | **t~½~= 8.8 days** @ 25 ^o^C, pH 5;            | 42     |
|            |                                                | 715201 |
| \[161-1\]  | **t~½~=139 days** @ 25 ^o^C, pH 7;             |        |
|            |                                                |        |
|            | **t~½~= 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              |        |
+------------+------------------------------------------------+--------+
| Direct     | **Combined labels results:**                   | 42     |
| photolysis |                                                | 182401 |
| in water   | **t~½~= 428 days** @ 24 ^o^C, pH 5;            |        |
|            |                                                | 43     |
| \[161-2\]  | **t~½~= stable** @ 24 ^o^C, pH 7;              | 174101 |
|            |                                                |        |
|            | **t~½~= stable** @ 24 ^o^C, pH 9.              |        |
|            |                                                |        |
|            | (calculated by the difference in degradation   |        |
|            | rates between irradiated 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.                                    |        |
+------------+------------------------------------------------+--------+
| Photolysis | **t~½~= 72.1 days** @ 25 ^o^C,                 | 41     |
| on soil    |                                                | 420601 |
|            | Study duration was 33 days, substantial        |        |
| \[161-3\]  | 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       |        |
|            | sulfonylurea 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 sulfometuron 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.                                 |        |
+------------+------------------------------------------------+--------+
| Aerobic    | [Study with \[pyrimidine-2-^14^C\]             | 42     |
| soil       | Sulfometuron Methyl]{.underline}               | 091401 |
| metabolism |                                                |        |
|            | **Soil: Keyport Silt loam (pH 6.3, 1.6% O.C.)  |        |
| \[162-1\]  | from Delaware**                                |        |
|            |                                                |        |
|            | First Order **t~½~**: 57.8 days (r^2^ =        |        |
|            | 0.9239).                                       |        |
|            |                                                |        |
|            | Observed DT50: 23 days.                        |        |
|            |                                                |        |
|            | Observed DT90: 110 days.                       |        |
|            |                                                |        |
|            | Sterile soil First Order **t~½~**: 364 days    |        |
|            |                                                |        |
|            | Major transformation 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.                             |        |
+------------+------------------------------------------------+--------+
| Aerobic    | [Study with U- ^14^C-phenyl-labeled            | 43     |
| soil       | Sulfometuron Methyl]{.underline}               | 174102 |
| metabolism |                                                | and    |
|            | **Soil: Keyport Silt loam (pH 6.4, 1.6 % O.C.) | 245375 |
| \[162-1\]  | from Delaware (0.12 mg a.i./kg).**             |        |
|            |                                                |        |
|            | First Order **t~½~**: 52.5 days (r^2^ =        |        |
|            | 0.9239).                                       |        |
|            |                                                |        |
|            | Observed DT50: 29 days.                        |        |
|            |                                                |        |
|            | Observed DT90: 162 days.                       |        |
|            |                                                |        |
|            | Major transformation products:                 |        |
|            |                                                |        |
|            | > 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)                                |        |
+------------+------------------------------------------------+--------+
| Anaerobic  | Study performed with \[pyrimidine-2-^14^C\]    | 42     |
| aquatic    | Sulfometuron Methyl                            | 091402 |
| metabolism |                                                | and    |
|            | **Matrix: Bradenton Pond water-sand            | 43     |
| \[162-3\]  | sediment.**                                    | 188601 |
|            |                                                |        |
|            | First Order **t~½~**: 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: Landenberg Pond water-sandy loam     |        |
|            | sediment.**                                    |        |
|            |                                                |        |
|            | First Order **t~½~**; 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.               |        |
|            | >                                              |        |
|            | > pyrimidine amine.                            |        |
|            |                                                |        |
|            | Minor identified transformation products:      |        |
|            |                                                |        |
|            | > pyrimidine-ol.                               |        |
|            | >                                              |        |
|            | > CO~2~.                                       |        |
+------------+------------------------------------------------+--------+
| Anaerobic  | Study with \[phenyl-U-^14^C\] Sulfometuron     | 4413   |
| aquatic    | Methyl                                         | 010-20 |
| metabolism |                                                | (1     |
|            | **Matrix: Pond water-sandy loam sediment from  | 43540) |
| \[162-3\]  | Bradenton, Florida.**                          |        |
|            |                                                |        |
|            | **(water pH 5.5 . Sediment: pH 5.1; O.C. = 5.9 |        |
|            | %).**                                          |        |
|            |                                                |        |
|            | First Order **t~½~**; total system: 104 days   |        |
|            | (r^2^ = 0.4883)\*.                             |        |
|            |                                                |        |
|            | Observed DT50 in total system: *ca.* 21 days.  |        |
|            |                                                |        |
|            | Sterile **t~½~**; 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~½~**; total system: 87 days    |        |
|            | (r^2^ = 0.3577).                               |        |
|            |                                                |        |
|            | Observed DT50 in total system: *ca.* 28 days.  |        |
|            |                                                |        |
|            | Sterile **t~½~**; total system: 175 days       |        |
|            |                                                |        |
|            | **Matrix: Pond water-loam sediment from        |        |
|            | Saskatoon, Canada. (water pH 8.3 . Sediment:   |        |
|            | pH 7.8; O.C. = 0.9 %).**                       |        |
|            |                                                |        |
|            | First Order **t~½~**; total system: 77 days    |        |
|            | (r^2^ = 0.5853).                               |        |
|            |                                                |        |
|            | Observed DT50 in total system: *ca.* 70 days.  |        |
|            |                                                |        |
|            | Sterile **t~½~**; 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~½~**; total system: 73 days    |        |
|            | (r^2^ = 0.5691).                               |        |
|            |                                                |        |
|            | Observed DT50 in total system: *ca.* 28 days.  |        |
|            |                                                |        |
|            | Sterile **t~½~**; total system: 95 days        |        |
|            |                                                |        |
|            | Major transformation products:                 |        |
|            |                                                |        |
|            | saccharin.                                     |        |
|            |                                                |        |
|            | free acid sulfonamide.                         |        |
|            |                                                |        |
|            | Minor identified transformation products:      |        |
|            |                                                |        |
|            | Methyl-2-aminocarbonyl(aminosulfonyl)benzoate. |        |
+------------+------------------------------------------------+--------+
| Aerobic    | Study performed with \[pyrimidine-2-^14^C\]    | 42     |
| aquatic    | Sulfometuron Methyl                            | 091403 |
| metabolism |                                                | and    |
|            | **Matrix used: Pond water-silt loam sediment   | 43     |
| \[162-4\]  | (****Landenberg, acidic system).**             | 174103 |
|            |                                                |        |
|            | First Order **t~½~**; total system: 9.2 days   |        |
|            | (r^2^ = 0.94).                                 |        |
|            |                                                |        |
|            | Observed DT50 in total system: 15 days.        |        |
|            |                                                |        |
|            | Observed DT90 in total system: 31 days         |        |
|            | (extrapolated).                                |        |
|            |                                                |        |
|            | Major transformation products:                 |        |
|            |                                                |        |
|            | > Pyrimidine amine (pyrimidine label).         |        |
|            | >                                              |        |
|            | > Hydroxymethyl-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~½~**; total system: 187.3 days |        |
|            | (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.                                      |        |
|            | >                                              |        |
|            | > Sulfonamide (phenyl label).                  |        |
|            | >                                              |        |
|            | > CO~2~.                                       |        |
+------------+------------------------------------------------+--------+
| A          | **[Parent sulfometuron methyl]{.underline}:**  | 42     |
| dsorption/ |                                                | 789301 |
|            | Soil type: Chino Sandy loam; pH 7.1, organic   |        |
| Desorption | carbon 1.0%.                                   |        |
|            |                                                |        |
| (K~d~ and  | Adsorption K~d~: 0.35.                         |        |
|            |                                                |        |
| **K~oc~**  | Adsorption K~oc~: 35.                          |        |
| in L       |                                                |        |
| Kg^-1^)    | Freundlich adsorption 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 type: 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%.                                   |        |
|            |                                                |        |
|            | Adsorption 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                                      |        |
+------------+------------------------------------------------+--------+
| A          | **[Pyrimidine amine]{.underline}**             | 42     |
| dsorption/ |                                                | 789301 |
|            | Although the registrant conducted adsorption / |        |
| Desorption | desorption studies for the pyrimidine amine    |        |
|            | degradate, the results were insufficiently     |        |
| Of         | documented to verify their calculations of     |        |
| Degradates | adsorption coefficients (and furthermore, they |        |
|            | only reported Freundlich adsorption "K~F~" and |        |
|            | "K~Foc~" values without 1/N values (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-dimethoxy rather than 4-, 6-dimethyl         |        |
|            | 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]{.underline}**                    |        |
|            |                                                |        |
|            | Although the registrant conducted 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 and 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://ec.europa.eu/food/plant/prot          |        |
|            | ection/evaluation/existactive/list1-13_en.pdf> |        |
|            | )                                              |        |
+------------+------------------------------------------------+--------+
| T          | Greenville, MS silty clay loam soil: pH 6.7,   | N      |
| errestrial | 0.6% O.C.                                      | umbers |
| Field      |                                                | 43     |
| /Lysimeter | Half-life: 49.2 days (based on 0- to 359-day   | 212101 |
|            | data);                                         | and    |
| D          |                                                | 43     |
| issipation | 12.2 days (based on 0- to 91-day data).        | 637101 |
| ^2^        |                                                |        |
|            | 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: 128 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 days (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   |        |
|            | data);                                         |        |
|            |                                                |        |
|            | 22.9 days (based on 0- to 180-day data).       |        |
|            |                                                |        |
|            | DT90: 55 days                                  |        |
|            |                                                |        |
|            | Major transformation products detected (\>0.01 |        |
|            | ppm):                                          |        |
|            |                                                |        |
|            | PYA, SFN, and SCC                              |        |
+------------+------------------------------------------------+--------+
| ^1^ Unless |                                                |        |
| otherwise  |                                                |        |
| specified, |                                                |        |
| half-lives |                                                |        |
| were       |                                                |        |
| derived    |                                                |        |
| with a     |                                                |        |
| "L         |                                                |        |
| og-linear" |                                                |        |
| d          |                                                |        |
| egradation |                                                |        |
| rate       |                                                |        |
| ca         |                                                |        |
| lculation; |                                                |        |
| a process  |                                                |        |
| of         |                                                |        |
| c          |                                                |        |
| alculating |                                                |        |
| d          |                                                |        |
| egradation |                                                |        |
| rates and  |                                                |        |
| half-lives |                                                |        |
| from       |                                                |        |
| linear     |                                                |        |
| regression |                                                |        |
| of         |                                                |        |
| log-t      |                                                |        |
| ransformed |                                                |        |
| con        |                                                |        |
| centration |                                                |        |
| me         |                                                |        |
| asurements |                                                |        |
| over time. |                                                |        |
| This       |                                                |        |
| provides a |                                                |        |
| f          |                                                |        |
| irst-order |                                                |        |
| type of    |                                                |        |
| m          |                                                |        |
| easurement |                                                |        |
| of         |                                                |        |
| pesticide  |                                                |        |
| decline.   |                                                |        |
|            |                                                |        |
| ^2^ For    |                                                |        |
| these      |                                                |        |
| field      |                                                |        |
| d          |                                                |        |
| issipation |                                                |        |
| studies,   |                                                |        |
| d          |                                                |        |
| ifferences |                                                |        |
| between    |                                                |        |
| half-lives |                                                |        |
| measured   |                                                |        |
| over       |                                                |        |
| various    |                                                |        |
| time       |                                                |        |
| durations  |                                                |        |
| apparently |                                                |        |
| reflect    |                                                |        |
| both       |                                                |        |
| slowing of |                                                |        |
| d          |                                                |        |
| egradation |                                                |        |
| at lower   |                                                |        |
| te         |                                                |        |
| mperatures |                                                |        |
| and a      |                                                |        |
| large      |                                                |        |
| v          |                                                |        |
| ariability |                                                |        |
| in         |                                                |        |
| measured   |                                                |        |
| conce      |                                                |        |
| ntrations; |                                                |        |
| also, a    |                                                |        |
| 2-c        |                                                |        |
| ompartment |                                                |        |
| d          |                                                |        |
| egradation |                                                |        |
| model for  |                                                |        |
| adsorbed   |                                                |        |
| and        |                                                |        |
| dissolved  |                                                |        |
| su         |                                                |        |
| lfometuron |                                                |        |
| is quite   |                                                |        |
| p          |                                                |        |
| ossibility |                                                |        |
| more       |                                                |        |
| a          |                                                |        |
| ppropriate |                                                |        |
| (little    |                                                |        |
| d          |                                                |        |
| issipation |                                                |        |
| of the     |                                                |        |
| remaining  |                                                |        |
| residues   |                                                |        |
| in the     |                                                |        |
| topsoil    |                                                |        |
| occurred   |                                                |        |
| during the |                                                |        |
| second     |                                                |        |
| year of    |                                                |        |
| these      |                                                |        |
| studies,   |                                                |        |
| for        |                                                |        |
| example).  |                                                |        |
| A          |                                                |        |
| 2-c        |                                                |        |
| ompartment |                                                |        |
| model was  |                                                |        |
| not used   |                                                |        |
| to         |                                                |        |
| represent  |                                                |        |
| d          |                                                |        |
| issipation |                                                |        |
| rate here  |                                                |        |
| because    |                                                |        |
| the data   |                                                |        |
| are not    |                                                |        |
| sufficient |                                                |        |
| robust     |                                                |        |
| (e.g.,     |                                                |        |
| very high  |                                                |        |
| v          |                                                |        |
| ariability |                                                |        |
| between    |                                                |        |
| replicate  |                                                |        |
| meas       |                                                |        |
| urements), |                                                |        |
| the        |                                                |        |
| effects of |                                                |        |
| weather    |                                                |        |
| changes on |                                                |        |
| d          |                                                |        |
| egradation |                                                |        |
| rate       |                                                |        |
| cannot     |                                                |        |
| easily be  |                                                |        |
| isolated,  |                                                |        |
| and the    |                                                |        |
| amount of  |                                                |        |
| residues   |                                                |        |
| lost       |                                                |        |
| through    |                                                |        |
| d          |                                                |        |
| issipation |                                                |        |
| out of the |                                                |        |
| topsoil    |                                                |        |
| also       |                                                |        |
| cannot be  |                                                |        |
| separated  |                                                |        |
| from the   |                                                |        |
| amount     |                                                |        |
| lost to    |                                                |        |
| de         |                                                |        |
| gradation. |                                                |        |
| At all     |                                                |        |
| four of    |                                                |        |
| these      |                                                |        |
| field      |                                                |        |
| study      |                                                |        |
| sites      |                                                |        |
| about 99%  |                                                |        |
| of the     |                                                |        |
| applied    |                                                |        |
| su         |                                                |        |
| lfometuron |                                                |        |
| methyl     |                                                |        |
| dissipated |                                                |        |
| from the   |                                                |        |
| topsoil    |                                                |        |
| within 3   |                                                |        |
| to 6       |                                                |        |
| months.    |                                                |        |
+------------+------------------------------------------------+--------+

### Measures of Aquatic Exposure

#### Aquatic Exposure Monitoring and Field 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 above the minimum
reporting limit of 0.05 ug/L in 12% of the samples collected 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.

#### Aquatic Exposure Modeling

EFED's PRZM ([P]{.underline}esticide [R]{.underline}oot
[Z]{.underline}one [M]{.underline}odel) and EXAMS
([EX]{.underline}posure [A]{.underline}nalysis [M]{.underline}odeling
[S]{.underline}ystem) models (Table 11) were used in this assessment to
estimate the exposure of sulfometuron methyl residues to the aquatic
environment as a result of the proposed uses in forestry and various
non-crop land vegetation control uses. PRZM 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 in 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 -- PE5.pl - which incorporates the standard scenarios
developed by EFED. (For additional information see
<http://www.epa.gov/oppefed1/models/water/index.htm>[)]{.underline}.
Potential exposure from ground-water (for, example, via contaminated
irrigation water) was also estimated using the SCI-GROW model.

+----------------------+-----------------------------------------------+
| []{#__RefHe          |                                               |
| ading___Toc191187625 |                                               |
| .anchor}Table 11.    |                                               |
| Models Used to       |                                               |
| Estimate Exposure    |                                               |
| Concentrations for   |                                               |
| Aquatic Ecosystem.   |                                               |
+----------------------+-----------------------------------------------+
| **Exposure Estimate  | **Models Used**                               |
| Type**               |                                               |
+----------------------+-----------------------------------------------+
| [Aquatic             | PE v5.0, PRZM v3.12.2, EXAMS v2.98.04.06      |
| eco                  |                                               |
| systems]{.underline} | Details of executables:                       |
|                      |                                               |
| Surface water (Tier  | PRZM 3.12.2, named przm3122.exe (dated May    |
| II)                  | 12, 2005)                                     |
|                      |                                               |
|                      | EXAMS 2.98.04.06, executable file named       |
|                      | EXAMS.EXE (dated April 12, 2005)              |
|                      |                                               |
|                      | PE v5.0, Executable file PE5.pl (dated July   |
|                      | 24, 2006)                                     |
+----------------------+-----------------------------------------------+
| Ground water (Tier   | SCI-GROW v2.3                                 |
| I)                   |                                               |
|                      | Executable file sg23.exe (dated May 16, 2006) |
+----------------------+-----------------------------------------------+

The estimated environmental concentrations (EECs) were predicted
assuming 1 aerial or ground application at the maximum allowable single
application rate of 0.375 lbs. a.i./A (which also represents 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 the 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 forestry 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]{.underline}**. 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 this 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
sulfometuron methyl

2\. **[Modeling with multiple application dates]{.underline}**. 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 that 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 reason 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) ranged
from 8.5 to 49.5 ug/L and the 90-day EECs ranged from 5.5 to 27.2
ug/L[^4]. 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 methyl 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 application date
model results were chosen for risk calculations.

Both 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 sulfometuron
methyl than aerial applications at the same site.

The pesticide-specific input parameters for this modeling (summarized in
Table 13) were selected from the environmental fate studies submitted by
the registrant, and in accordance 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 sulfometuron 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 (electronic 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 hydrolysis, aerobic aquatic metabolism, and anaerobic
aquatic metabolism hand to be assumed (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). Further details on the limitations
of the modeling and uncertainties regarding exposure to sulfometuron
methyl degradates are provided in Section 3.2.4.3.

+----------+------+------+------+--------+--------------------------+
| []{#__R  |      |      |      |        |                          |
| efHeadin |      |      |      |        |                          |
| g___Toc1 |      |      |      |        |                          |
| 91187626 |      |      |      |        |                          |
| .anch    |      |      |      |        |                          |
| or}Table |      |      |      |        |                          |
| 12.      |      |      |      |        |                          |
| Aquatic  |      |      |      |        |                          |
| exposure |      |      |      |        |                          |
| with     |      |      |      |        |                          |
| PRZM --  |      |      |      |        |                          |
| EXAMS:   |      |      |      |        |                          |
| Modeling |      |      |      |        |                          |
| s        |      |      |      |        |                          |
| cenarios |      |      |      |        |                          |
| and      |      |      |      |        |                          |
| repres   |      |      |      |        |                          |
| entative |      |      |      |        |                          |
| usage    |      |      |      |        |                          |
| pattern  |      |      |      |        |                          |
| summary. |      |      |      |        |                          |
+----------+------+------+------+--------+--------------------------+
| Scenario | WBAN | a    | CA   | app    | Use(s) represented       |
| ID^1^    | (    | ppl. | M^3^ | lictn. |                          |
|          | met. | m    |      | dates  |                          |
|          | file | eth. |      | (      |                          |
|          | )^2^ |      |      | MM-DD) |                          |
+----------+------+------+------+--------+--------------------------+
| PA       | W1   | Ae   | 2    | 03-15  | Forestry, Conifer        |
| Apples   | 4751 | rial |      |        | Plantations              |
| (std)    |      |      |      |        |                          |
+----------+------+------+------+--------+--------------------------+
| FL       | W1   | Gr   | 1    | 03-01  | Forestry, Conifer        |
| Citrus   | 2844 | ound |      |        | Plantations              |
| (std)    |      |      |      |        |                          |
+----------+------+------+------+--------+--------------------------+
| FL       | W1   | Ae   | 1    | 03-01  | Forestry, Conifer        |
| Citrus   | 2844 | rial |      |        | Plantations              |
| (std)    |      |      |      |        |                          |
+----------+------+------+------+--------+--------------------------+
| FL Turf  | W1   | Gr   | 1    | 03-01  | Non-crop (e.g.,          |
| (std)    | 2834 | ound |      |        | unimproved turf & rights |
|          |      |      |      |        | of way)                  |
+----------+------+------+------+--------+--------------------------+
| FL Turf  | W1   | Ae   | 2    | 03-01  | Unimproved turf,         |
| (std)    | 2834 | rial |      |        | non-crop                 |
+----------+------+------+------+--------+--------------------------+
| PA Turf  | W1   | Ae   | 2    | 03-01  | Unimproved turf,         |
| (std)    | 4751 | rial |      |        | non-crop                 |
+----------+------+------+------+--------+--------------------------+
| OR Xmas  | W2   | Gr   | 1    | 03-01  | Christmas Trees,         |
| Trees    | 4232 | ound |      |        | Forestry, Conifer        |
| (std)    |      |      |      |        | Plantations              |
+----------+------+------+------+--------+--------------------------+
| OR Xmas  | W2   | Ae   | 2    | 03-01  | Christmas Trees,         |
| Trees    | 4232 | rial |      |        | Forestry, Conifer        |
| (std)    |      |      |      |        | Plantations              |
+----------+------+------+------+--------+--------------------------+
| CA right | W2   | Ae   | 2    | 03-01  | Non-Crop (rights of way, |
| of way   | 3234 | rial |      |        | unimproved turf,         |
| (RLF)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| CA right | W9   | Ae   | 2    | 03-01  | Non-Crop (rights of way, |
| of way   | 4224 | rial |      |        | unimproved turf,         |
| (RLF)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| CA right | W9   | Ae   | 2    | Feb to | Non-Crop (rights of way, |
| of way   | 4224 | rial |      | Oct^4^ | unimproved turf,         |
| (RLF)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| TX right | W1   | Ae   | 2    | 03-01  | Non-Crop (rights of way, |
| of way   | 3958 | rial |      |        | unimproved turf,         |
| (BSS)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| TX right | W1   | Ae   | 2    | 03-01  | Non-Crop (rights of way, |
| of way   | 2917 | rial |      |        | unimproved turf,         |
| (BSS)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| TX right | W1   | Ae   | 2    | Feb to | Non-Crop (rights of way, |
| of way   | 2917 | rial |      | Oct^4^ | unimproved turf,         |
| (BSS)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| TX right | W1   | Gr   | 2    | Feb to | Non-Crop (rights of way, |
| of way   | 2917 | ound |      | Oct^4^ | unimproved turf,         |
| (BSS)    |      |      |      |        | railroads, etc.)         |
+----------+------+------+------+--------+--------------------------+
| ^1^      |      |      |      |        |                          |
| Native   |      |      |      |        |                          |
| scenario |      |      |      |        |                          |
| des      |      |      |      |        |                          |
| ignation |      |      |      |        |                          |
| state    |      |      |      |        |                          |
| and use  |      |      |      |        |                          |
| site.    |      |      |      |        |                          |
| Native   |      |      |      |        |                          |
| scenario |      |      |      |        |                          |
| target   |      |      |      |        |                          |
| in       |      |      |      |        |                          |
| pare     |      |      |      |        |                          |
| nthesis, |      |      |      |        |                          |
| where:   |      |      |      |        |                          |
| std =    |      |      |      |        |                          |
| std      |      |      |      |        |                          |
| scenario |      |      |      |        |                          |
| used in  |      |      |      |        |                          |
| na       |      |      |      |        |                          |
| tionwide |      |      |      |        |                          |
| asse     |      |      |      |        |                          |
| ssments; |      |      |      |        |                          |
| RLF =    |      |      |      |        |                          |
| scenario |      |      |      |        |                          |
| or       |      |      |      |        |                          |
| iginally |      |      |      |        |                          |
| d        |      |      |      |        |                          |
| eveloped |      |      |      |        |                          |
| for      |      |      |      |        |                          |
| regional |      |      |      |        |                          |
| ass      |      |      |      |        |                          |
| essments |      |      |      |        |                          |
| related  |      |      |      |        |                          |
| to the   |      |      |      |        |                          |
| Ca       |      |      |      |        |                          |
| lifornia |      |      |      |        |                          |
| re       |      |      |      |        |                          |
| d-legged |      |      |      |        |                          |
| frog;    |      |      |      |        |                          |
| and BSS  |      |      |      |        |                          |
| =        |      |      |      |        |                          |
| scenario |      |      |      |        |                          |
| or       |      |      |      |        |                          |
| iginally |      |      |      |        |                          |
| d        |      |      |      |        |                          |
| eveloped |      |      |      |        |                          |
| for      |      |      |      |        |                          |
| regional |      |      |      |        |                          |
| ass      |      |      |      |        |                          |
| essments |      |      |      |        |                          |
| related  |      |      |      |        |                          |
| to the   |      |      |      |        |                          |
| Barton   |      |      |      |        |                          |
| Springs  |      |      |      |        |                          |
| sal      |      |      |      |        |                          |
| amander. |      |      |      |        |                          |
|          |      |      |      |        |                          |
| ^2^ The  |      |      |      |        |                          |
| Weather  |      |      |      |        |                          |
| Bureau   |      |      |      |        |                          |
| A        |      |      |      |        |                          |
| utomated |      |      |      |        |                          |
| Network  |      |      |      |        |                          |
| (WBAN)   |      |      |      |        |                          |
| meteor   |      |      |      |        |                          |
| ological |      |      |      |        |                          |
| station  |      |      |      |        |                          |
| used for |      |      |      |        |                          |
| weather  |      |      |      |        |                          |
| inputs   |      |      |      |        |                          |
| in the   |      |      |      |        |                          |
| runoff   |      |      |      |        |                          |
| m        |      |      |      |        |                          |
| odeling. |      |      |      |        |                          |
|          |      |      |      |        |                          |
| ^3^ CAM  |      |      |      |        |                          |
| =        |      |      |      |        |                          |
| Chemical |      |      |      |        |                          |
| app      |      |      |      |        |                          |
| lication |      |      |      |        |                          |
| method.  |      |      |      |        |                          |
| CAM 1 is |      |      |      |        |                          |
| app      |      |      |      |        |                          |
| lication |      |      |      |        |                          |
| direct   |      |      |      |        |                          |
| to soil, |      |      |      |        |                          |
| although |      |      |      |        |                          |
| a 4 cm   |      |      |      |        |                          |
| incor    |      |      |      |        |                          |
| poration |      |      |      |        |                          |
| depth is |      |      |      |        |                          |
|          |      |      |      |        |                          |
| autom    |      |      |      |        |                          |
| atically |      |      |      |        |                          |
| assumed, |      |      |      |        |                          |
| to       |      |      |      |        |                          |
| account  |      |      |      |        |                          |
| for      |      |      |      |        |                          |
| surface  |      |      |      |        |                          |
| ro       |      |      |      |        |                          |
| ughness. |      |      |      |        |                          |
| CAM 2 is |      |      |      |        |                          |
| linear   |      |      |      |        |                          |
| foliar   |      |      |      |        |                          |
| decay    |      |      |      |        |                          |
| based on |      |      |      |        |                          |
| crop     |      |      |      |        |                          |
| canopy,  |      |      |      |        |                          |
| default  |      |      |      |        |                          |
| soil     |      |      |      |        |                          |
| incor    |      |      |      |        |                          |
| poration |      |      |      |        |                          |
| depth    |      |      |      |        |                          |
| for      |      |      |      |        |                          |
| no       |      |      |      |        |                          |
| n-foliar |      |      |      |        |                          |
| int      |      |      |      |        |                          |
| ercepted |      |      |      |        |                          |
| chemical |      |      |      |        |                          |
| is 4 cm. |      |      |      |        |                          |
|          |      |      |      |        |                          |
| ^4^ Only |      |      |      |        |                          |
| one      |      |      |      |        |                          |
| app      |      |      |      |        |                          |
| lication |      |      |      |        |                          |
| per year |      |      |      |        |                          |
| in each  |      |      |      |        |                          |
| model    |      |      |      |        |                          |
| run.     |      |      |      |        |                          |
| PR       |      |      |      |        |                          |
| ZM-EXAMS |      |      |      |        |                          |
| was      |      |      |      |        |                          |
| se       |      |      |      |        |                          |
| parately |      |      |      |        |                          |
| run for  |      |      |      |        |                          |
| app      |      |      |      |        |                          |
| lication |      |      |      |        |                          |
| dates    |      |      |      |        |                          |
| between  |      |      |      |        |                          |
| February |      |      |      |        |                          |
| 1 and    |      |      |      |        |                          |
| October  |      |      |      |        |                          |
| 29,      |      |      |      |        |                          |
| in       |      |      |      |        |                          |
| creasing |      |      |      |        |                          |
| the      |      |      |      |        |                          |
| app      |      |      |      |        |                          |
| lication |      |      |      |        |                          |
| date by  |      |      |      |        |                          |
| 10       |      |      |      |        |                          |
| Julian   |      |      |      |        |                          |
| days     |      |      |      |        |                          |
| with     |      |      |      |        |                          |
| each     |      |      |      |        |                          |
| su       |      |      |      |        |                          |
| ccessive |      |      |      |        |                          |
| model    |      |      |      |        |                          |
| run      |      |      |      |        |                          |
| (2/1,    |      |      |      |        |                          |
| 2/11,    |      |      |      |        |                          |
| 2/21,    |      |      |      |        |                          |
| etc.).   |      |      |      |        |                          |
+----------+------+------+------+--------+--------------------------+

+---------------------+--------------+---------------------------------+
| []{#__RefHea        |              |                                 |
| ding___Toc191187627 |              |                                 |
| .anchor}Table 13.   |              |                                 |
| PRZM/EXAMS input    |              |                                 |
| parameters for      |              |                                 |
| modeling (Aquatic   |              |                                 |
| ecological EECs).   |              |                                 |
+=====================+==============+=================================+
| ***Input            | *            | ***Reference***                 |
| Parameter***        | **Value\**** |                                 |
+---------------------+--------------+---------------------------------+
| **Molecular Weight  | 364.38       | MRID: 416728-02                 |
| (gram mole ^-1^)**  |              |                                 |
+---------------------+--------------+---------------------------------+
| **Vapor Pressure    | 5.4x10^-16^  |                                 |
| (torr)**            |              |                                 |
+---------------------+--------------+---------------------------------+
| **Aerobic Soil      | 60.9         | 90% Upper Confidence Limit of   |
| Metabolism          |              | the mean of measured values     |
| Half-life (days)**  |              | (MRIDs 42091401; 43174102 and   |
|                     |              | 245375)                         |
+---------------------+--------------+---------------------------------+
| **Water column      | 292          | 90% Upper Confidence Limit of   |
| Half-life (days)**  |              | the mean of measured values     |
|                     |              | (MRIDs 42091403 and 43174103 )  |
| **(Aerobic Aquatic  |              |                                 |
| Metabolism          |              |                                 |
| half-life)**        |              |                                 |
+---------------------+--------------+---------------------------------+
| **Benthic sediment  | 76           | 90% Upper Confidence Limit of   |
| Half-life (days)**  |              | the mean of measured values     |
|                     |              | (MRIDs 43174102, 245375,        |
| **(Anaerobic        |              | 42091402, and 43188601)         |
| Aquatic Metabolism  |              |                                 |
| half-life)**        |              |                                 |
+---------------------+--------------+---------------------------------+
| **Application Rate  | 0.41         | Efficiency= 0.99 for ground     |
| (Kg a.i./ha)**      |              | spray, 0.95 for aerial.         |
+---------------------+--------------+---------------------------------+
| **Application       | One          | Product Label; typical use.     |
| Number (Method of   |              |                                 |
| application)**      |              |                                 |
+---------------------+--------------+---------------------------------+
| **Application       | Aerial or    | CAM=1 or CAM=2 depending on the |
| method; Depth of    | ground;      | use.                            |
| Incorporation       |              |                                 |
| (cm)**              | 0            |                                 |
+---------------------+--------------+---------------------------------+
| **Spray Drift       | 0.01 (GS),   | Default values per guidance     |
| (fraction)**        | 0.05         | document. (GS= ground spray)    |
|                     | (aerial)     |                                 |
+---------------------+--------------+---------------------------------+
| **Solubility        | 244          | Highest solubility was recorded |
| (ppm)**             |              | 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          | 47.5         | Average of four values (MRID    |
| Kg^-1^)**           |              | 42789301).                      |
|                     |              |                                 |
|                     |              | K~oc~ model was determined to   |
|                     |              | be appropriate.                 |
+---------------------+--------------+---------------------------------+
| **Hydrolysis        | 139 days     | MRID 42715201.                  |
| Half-life @ pH 7    |              |                                 |
| (days)**            |              |                                 |
+---------------------+--------------+---------------------------------+
| **Direct Aqueous    | Stable       | Maximum dark control corrected  |
| Photolysis          |              | value (MRIDs 42182401 and       |
| Half-life(days)**   |              | 43174101)                       |
+---------------------+--------------+---------------------------------+

Fate data values are as per Guidance for Selecting 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, Texas
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 southeastern 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 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 about the same, but
the chronic EECs estimated would be lower).

<table>
<colgroup>
<col style="width: 23%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 11%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="11"><p><span id="__RefHeading___Toc191187628"
class="anchor"></span>Table 14. Estimated environmental concentrations
(µg/L) for aquatic exposure to parent sulfometuron methyl:
scenario-specific results from PRZM-EXAMS modeling.</p>
<p>(all values are listed as ppb or ug/L)</p></td>
</tr>
<tr class="even">
<td><em><strong>Scenario Description</strong></em></td>
<td><em><strong>Site</strong></em><sup>1</sup></td>
<td><em><strong>Peak</strong></em></td>
<td><em><strong>96 hr</strong></em></td>
<td><em><strong>21 Day</strong></em></td>
<td><em><strong>60 Day</strong></em></td>
<td><em><strong>90 Day</strong></em></td>
<td><em><strong>Yearly</strong></em></td>
<td><em><strong>Lifetime</strong></em></td>
<td><em><strong>Applictn. Date, mm-yy</strong></em></td>
<td><em><strong>App-Type</strong></em><sup>3</sup></td>
</tr>
<tr class="odd">
<td>PA Apple</td>
<td>Fr</td>
<td>2.28</td>
<td>2.23</td>
<td>2.05</td>
<td>1.61</td>
<td>1.39</td>
<td>0.45</td>
<td>0.31</td>
<td>3-15</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>FL Citrus</td>
<td>Fr</td>
<td>9.39</td>
<td>9.09</td>
<td>7.97</td>
<td>6.03</td>
<td>4.93</td>
<td>1.48</td>
<td>0.72</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>FL Citrus</td>
<td>Fr</td>
<td>7.32</td>
<td>7.08</td>
<td>6.19</td>
<td>4.71</td>
<td>3.81</td>
<td>1.14</td>
<td>0.43</td>
<td>3-01</td>
<td>ground</td>
</tr>
<tr class="even">
<td>FL Turf</td>
<td>NC</td>
<td>1.47</td>
<td>1.43</td>
<td>1.27</td>
<td>1.01</td>
<td>0.86</td>
<td>0.29</td>
<td>0.20</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>FL Turf</td>
<td>NC</td>
<td>0.46</td>
<td>0.44</td>
<td>0.39</td>
<td>0.30</td>
<td>0.25</td>
<td>0.09</td>
<td>0.05</td>
<td>3-01</td>
<td>ground</td>
</tr>
<tr class="even">
<td>PA Turf</td>
<td>NC</td>
<td>1.22</td>
<td>1.20</td>
<td>1.12</td>
<td>0.96</td>
<td>0.84</td>
<td>0.29</td>
<td>0.26</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>OR Xmas</td>
<td>Fr</td>
<td>1.57</td>
<td>1.53</td>
<td>1.42</td>
<td>1.21</td>
<td>1.06</td>
<td>0.40</td>
<td>0.29</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>OR(Astoria) Xmas</td>
<td>Fr</td>
<td>2.87</td>
<td>2.82</td>
<td>2.61</td>
<td>2.18</td>
<td>1.91</td>
<td>0.73</td>
<td>0.42</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>OR(Astoria) Xmas</td>
<td>Fr</td>
<td>1.78</td>
<td>1.74</td>
<td>1.58</td>
<td>1.29</td>
<td>1.13</td>
<td>0.43</td>
<td>0.35</td>
<td>9-01</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>CA RightsWay</td>
<td>NC</td>
<td>8.33</td>
<td>8.15</td>
<td>7.47</td>
<td>6.17</td>
<td>5.35</td>
<td>2.00</td>
<td>0.84</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>CA(As-OR) <sup>4</sup> RightsWay</td>
<td>NC</td>
<td>13.64</td>
<td>13.37</td>
<td>12.39</td>
<td>10.35</td>
<td>9.04</td>
<td>3.42</td>
<td>1.34</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>CA(As-OR) RightsWay 90<sup>th</sup> date<sup>5</sup></td>
<td>NC</td>
<td>11.01</td>
<td>10.83</td>
<td>10.10</td>
<td>8.46</td>
<td>6.73</td>
<td>2.73</td>
<td>1.44</td>
<td>various <sup>6</sup></td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>TX RightsWay</td>
<td>NC</td>
<td>6.96</td>
<td>6.74</td>
<td>5.99</td>
<td>4.72</td>
<td>3.94</td>
<td>1.22</td>
<td>0.64</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>TX(PtAr) <sup>7</sup> RightsWay</td>
<td>NC</td>
<td>11.87</td>
<td>11.55</td>
<td>10.66</td>
<td>8.84</td>
<td>7.41</td>
<td>2.30</td>
<td>1.06</td>
<td>3-01</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>TX(PtAr) RightsWay 50<sup>th</sup> date</td>
<td>NC</td>
<td>21.75</td>
<td>20.93</td>
<td>18.33</td>
<td>13.51</td>
<td>10.99</td>
<td>3.39</td>
<td>1.97</td>
<td>Various</td>
<td>aerial</td>
</tr>
<tr class="even">
<td>TX(PtAr) RightsWay 90<sup>th</sup> date</td>
<td>NC</td>
<td>31.45</td>
<td>30.34</td>
<td>26.24</td>
<td>20.45</td>
<td>16.49</td>
<td>5.26</td>
<td>3.14</td>
<td>Various</td>
<td>aerial</td>
</tr>
<tr class="odd">
<td>TX(PtAr) RightsWay 90<sup>th</sup> date</td>
<td>NC</td>
<td>26.08</td>
<td>25.20</td>
<td>21.64</td>
<td>15.51</td>
<td>12.48</td>
<td>3.92</td>
<td>2.05</td>
<td>Various</td>
<td>ground</td>
</tr>
<tr class="even">
<td colspan="11"><p><sup>1</sup> Fr = forestry plantings uses. NC =
Non-crop uses on rights of way, industrial land with unimproved turf, on
ground prior to paving, railroads, etc.</p>
<p><sup>2</sup> CAF = crop area factor.</p>
<p><sup>3</sup> App-Type = application type.</p>
<p><sup>4</sup> As-OR = Astoria, Oregon meteorological weather
substituted for the original San Francisco, CA weather data for this
regional scenario.</p>
<p><sup>5</sup> 90<sup>th</sup> Date or 50<sup>th</sup> Date = For the
specified exposure distribution the 90<sup>th</sup> percentile of the
10<sup>th</sup> percentile exceedence probability (1 in 10 year return
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.</p>
<p><sup>6</sup> Pt-Ar = Port Arthur, Texas meteorological weather
substituted for the original Austin, TX weather data for this regional
scenario.</p>
<p><sup>7</sup> Only one application per year in each 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.).</p></td>
</tr>
</tbody>
</table>

+---------+-------+-------+-------+--------+--------+--------+-------+
| []{     |       |       |       |        |        |        |       |
| #__RefH |       |       |       |        |        |        |       |
| eading_ |       |       |       |        |        |        |       |
| __Toc19 |       |       |       |        |        |        |       |
| 1187629 |       |       |       |        |        |        |       |
| .ancho  |       |       |       |        |        |        |       |
| r}Table |       |       |       |        |        |        |       |
| 15.     |       |       |       |        |        |        |       |
| Sulfo   |       |       |       |        |        |        |       |
| meturon |       |       |       |        |        |        |       |
| methyl  |       |       |       |        |        |        |       |
| surface |       |       |       |        |        |        |       |
| water   |       |       |       |        |        |        |       |
| EECs    |       |       |       |        |        |        |       |
| used in |       |       |       |        |        |        |       |
| aquatic |       |       |       |        |        |        |       |
| risk    |       |       |       |        |        |        |       |
| asse    |       |       |       |        |        |        |       |
| ssment. |       |       |       |        |        |        |       |
|         |       |       |       |        |        |        |       |
| []      |       |       |       |        |        |        |       |
| {.mark} |       |       |       |        |        |        |       |
+---------+-------+-------+-------+--------+--------+--------+-------+
| **      |       |       |       |        |        |        |       |
| Surface |       |       |       |        |        |        |       |
| Water   |       |       |       |        |        |        |       |
| EECs in |       |       |       |        |        |        |       |
| ug      |       |       |       |        |        |        |       |
| /L^1^** |       |       |       |        |        |        |       |
+---------+-------+-------+-------+--------+--------+--------+-------+
| **Appl  | **P   | **96  | **21- | **60   | **90   | **     | **Y   |
| ication | eak** | -hr** | day** | -day** | -day** | Annual | early |
| m       |       |       |       |        |        | Ave    | Aver  |
| ethod** |       |       |       |        |        | rage** | age** |
+---------+-------+-------+-------+--------+--------+--------+-------+
| 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 from
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 concentrations 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 estimated 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.

+---------------------+----------------+-------------------------------+
| []{#__RefHea        |                |                               |
| ding___Toc191187630 |                |                               |
| .anchor}Table 16.   |                |                               |
| Estimated           |                |                               |
| concentrations of   |                |                               |
| sulfometuron methyl |                |                               |
| in ground water     |                |                               |
| (SCI-GROW inputs    |                |                               |
| and results).       |                |                               |
+=====================+================+===============================+
| ***Input            | ***Value\****  | ***Reference***               |
| Parameter***        |                |                               |
+---------------------+----------------+-------------------------------+
| **Aerobic Soil      | 55.2           | Mean of measured values       |
| Metabolism          |                | (MRIDs 42091401; 43174102 and |
| Half-life (days)**  |                | 245375)                       |
+---------------------+----------------+-------------------------------+
| **Application Rate  | 0.41           | Maximum permitted single (and |
| (Kg a.i./ha)**      |                | annual) rate.                 |
+---------------------+----------------+-------------------------------+
| **Application       | One            | Typical use.                  |
| Number (Method of   |                |                               |
| application)**      |                |                               |
+---------------------+----------------+-------------------------------+
| **K~oc~ (L          | 73.4           | Median of four values (MRID   |
| Kg^-1^)**           |                | 42789301).                    |
+---------------------+----------------+-------------------------------+
| > ***SCI-GROW       |                |                               |
| > Modeling          |                |                               |
| > Results***        |                |                               |
+---------------------+----------------+-------------------------------+
| **Acute Exposure    | 0.33           |                               |
| EEC, ug/L**         |                |                               |
+---------------------+----------------+-------------------------------+
| **Chronic Exposure  | 0.33           |                               |
| EEC, ug/L**         |                |                               |
+---------------------+----------------+-------------------------------+

### Measures of Terrestrial Exposure

#### Terrestrial Exposure Modeling

***Terrestrial Animals.*** Estimates of terrestrial wildlife exposure to
pesticides are typically evaluated for the dietary pathway for birds and
mammals (USEPA, 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 and 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 application methods for sulfometuron methyl are considered,
since labeling does not permit granular applications.

Estimating sulfometuron methyl concentrations on wildlife food items
focuses on quantifying possible dietary ingestion of residues on
vegetative matter and insects. No field residue data or field study
information is available for sulfometuron methyl except for lump
dissipation rates from the application of sulfometuron methyl to two
forest sites (MRIDs 42091404 and 43174104), therefore, the residue
estimates were based on a nomogram that 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 is 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 the 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 \[132-1\]). Although 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 items may be compared directly with dietary
toxicity data or converted to an oral dose and compared to dose-based
toxicity data. This screening-level risk assessment for sulfometuron
methyl uses estimated upper bound (i.e., 90^th^ percentile) residues as
the initial 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 application season, these EECs are considered
to represent an estimate of the upper bound exposure following
sulfometuron methyl 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

+----------+----------------+---------------------+-------------------+
| []{#__R  |                |                     |                   |
| efHeadin |                |                     |                   |
| g___Toc1 |                |                     |                   |
| 91187631 |                |                     |                   |
| .anch    |                |                     |                   |
| or}Table |                |                     |                   |
| 17.      |                |                     |                   |
| Un       |                |                     |                   |
| adjusted |                |                     |                   |
| Dietary  |                |                     |                   |
| Ter      |                |                     |                   |
| restrial |                |                     |                   |
| EECs for |                |                     |                   |
| Birds    |                |                     |                   |
| and      |                |                     |                   |
| Mammals  |                |                     |                   |
| F        |                |                     |                   |
| ollowing |                |                     |                   |
| Sulf     |                |                     |                   |
| ometuron |                |                     |                   |
| Methyl   |                |                     |                   |
| Spray    |                |                     |                   |
| App      |                |                     |                   |
| lication |                |                     |                   |
| For      |                |                     |                   |
| Non-Crop |                |                     |                   |
| Ve       |                |                     |                   |
| getative |                |                     |                   |
| Man      |                |                     |                   |
| agement. |                |                     |                   |
+----------+----------------+---------------------+-------------------+
| **Uses** | **\# of App. x | **Food Items**      | **Upper Bound     |
|          | App. Rate**    |                     | EECs**            |
|          |                |                     |                   |
|          | **(application |                     | **(ppm)**         |
|          | method)**      |                     |                   |
+----------+----------------+---------------------+-------------------+
| Non-Crop | 1 x 0.375 lb   | Short Grass         | 90.0              |
| Ve       | a.i./A         |                     |                   |
| getative |                | Tall Grass          | 41.3              |
| Ma       | (ground        |                     |                   |
| nagement | broadcast)     | Sm. Insects,        | 50.6              |
| ^1^      |                | Broadleaf Plants    |                   |
|          |                |                     | 5.6               |
|          |                | Lg. Insects,        |                   |
|          |                | Fruits, Pods        |                   |
+----------+----------------+---------------------+-------------------+

^1^ Includes uses on unimproved turf, forestry (Christmas trees & other
conifer plantations), non-crop vegetative management 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
drift and runoff are important factors in characterizing the risk of
sulfometuron methyl to non-target plants, which is assumed to reach
off-site areas. Two different models were used to evaluate impacts on
terrestrial plants:

1.  TerrPlant, which focuses more 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 on spray drift; only environmental
    concentrations 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 semi-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-aquatic
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 area (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, the 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 water (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 EECs (expressed as a
fraction of the application rate) following single, aerial and ground
spray application at the maximum application rate of sulfometuron methyl
are summarized in Table 18. Details on inputs and outputs from the
TerrPlant model are provided in "APPENDIX D: Terrplant Spreadsheet".

+------------+------------+-------------+----------------+-----------+
| [          |            |             |                |           |
| ]{#__RefHe |            |             |                |           |
| ading___To |            |             |                |           |
| c191187632 |            |             |                |           |
| .an        |            |             |                |           |
| chor}Table |            |             |                |           |
| 18. EECs   |            |             |                |           |
| for        |            |             |                |           |
| T          |            |             |                |           |
| errestrial |            |             |                |           |
| Plants     |            |             |                |           |
| Located    |            |             |                |           |
| Adjacent   |            |             |                |           |
| to         |            |             |                |           |
| Su         |            |             |                |           |
| lfometuron |            |             |                |           |
| Methyl     |            |             |                |           |
| (aerial    |            |             |                |           |
| and ground |            |             |                |           |
| spray      |            |             |                |           |
| ap         |            |             |                |           |
| plication) |            |             |                |           |
| Treated    |            |             |                |           |
| Sites.     |            |             |                |           |
+------------+------------+-------------+----------------+-----------+
| **T        | **A        | **EEC (lbs  |                |           |
| errestrial | pplication | ai/A)**     |                |           |
| Use**      | Method**   |             |                |           |
|            |            |             |                |           |
|            | **(Non-g   |             |                |           |
|            | ranular)** |             |                |           |
+------------+------------+-------------+----------------+-----------+
|            |            | **Total     | **Total        | **Drift   |
|            |            | Loading to  | Loading to     | to        |
|            |            | Dry Areas   | Semi-Aquatic   | Adjacent  |
|            |            | Adjacent to | Areas Adjacent | A         |
|            |            | Treated     | to Treated     | reas^4^** |
|            |            | Areas^2^**  | Areas^3^**     |           |
+------------+------------+-------------+----------------+-----------+
| Vegetative | Aerial     | 0.038       | 0.21           | 0.019     |
| managem    |            |             |                |           |
| ent**^1^** |            |             |                |           |
|            |            |             |                |           |
| (1 x 0.375 |            |             |                |           |
| lb ai/A)   |            |             |                |           |
+------------+------------+-------------+----------------+-----------+
|            | Ground     | 0.023       | 0.19           | 0.0038    |
|            | (uninc     |             |                |           |
|            | orporated) |             |                |           |
+------------+------------+-------------+----------------+-----------+
| ^1^        |            |             |                |           |
| Includes   |            |             |                |           |
| uses on    |            |             |                |           |
| unimproved |            |             |                |           |
| turf,      |            |             |                |           |
| forestry   |            |             |                |           |
| (Christmas |            |             |                |           |
| trees &    |            |             |                |           |
| other      |            |             |                |           |
| conifer    |            |             |                |           |
| pla        |            |             |                |           |
| ntations), |            |             |                |           |
| non-crop   |            |             |                |           |
| vegetative |            |             |                |           |
| management |            |             |                |           |
| including  |            |             |                |           |
| roadsides, |            |             |                |           |
| railroads  |            |             |                |           |
| and        |            |             |                |           |
| industrial |            |             |                |           |
| sites      |            |             |                |           |
|            |            |             |                |           |
| ^2^ EEC =  |            |             |                |           |
| Sheet      |            |             |                |           |
| Runoff +   |            |             |                |           |
| Drift (5%  |            |             |                |           |
| for aerial |            |             |                |           |
| or 1% for  |            |             |                |           |
| ground)    |            |             |                |           |
| assuming   |            |             |                |           |
| 1:1 runoff |            |             |                |           |
| loading    |            |             |                |           |
| ratio      |            |             |                |           |
|            |            |             |                |           |
| ^3^ EEC =  |            |             |                |           |
| C          |            |             |                |           |
| hannelized |            |             |                |           |
| 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     |            |             |                |           |
| a          |            |             |                |           |
| pplication |            |             |                |           |
| (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] AgDRIFT® (version 2.01)
modeling is also provided to better characterize potential exposure of
terrestrial plants. 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. Table 20 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 the 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 are
    not necessarily typical or recommended, but are plausible and
    permitted on the label. See columns B and D.

For ground applications, there is only a "Tier 1" module in AgDRIFT, but
there are some input options still available to vary. For this
assessment, only the boom height was varied between the 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 set
    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 labels. 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-site (the
percentage difference between estimates with each scenario increases
with increasing distance from the targeted field); see Table 20 and
Table 21.

+-------------+-------------+-----------------------------------------+
| []{#__Ref   |             |                                         |
| Heading___T |             |                                         |
| oc191187633 |             |                                         |
| .a          |             |                                         |
| nchor}Table |             |                                         |
| 19.         |             |                                         |
| Selected    |             |                                         |
| AgDRIFT     |             |                                         |
| inputs for  |             |                                         |
| high-end    |             |                                         |
| exposure    |             |                                         |
| from aerial |             |                                         |
| a           |             |                                         |
| pplications |             |                                         |
| of          |             |                                         |
| s           |             |                                         |
| ulfometuron |             |                                         |
| methyl      |             |                                         |
| using best  |             |                                         |
| management  |             |                                         |
| practices.  |             |                                         |
+-------------+-------------+-----------------------------------------+
| **Input     | **Input     | **Justification**                       |
| type**      | value**     |                                         |
+-------------+-------------+-----------------------------------------+
| Aircraft    | Air Tractor | Commonly used aircraft. Typical size    |
|             | AT-401      | and weight. Aircraft type does not      |
|             |             | greatly affect drift.                   |
+-------------+-------------+-----------------------------------------+
| Boom length | 76.3% of    | Recommended to reduce drift and         |
|             | wingspan    | increase application efficiency.        |
|             |             | Greater boom lengths generate more      |
|             |             | drift. 3/4 wingspan should be specified |
|             |             | on the label.                           |
+-------------+-------------+-----------------------------------------+
| Release     | 15 ft.      | Estimated upper bound under normal      |
| (boom)      |             | conditions. Should be specified on      |
| height      |             | labels with no-spray zones.             |
+-------------+-------------+-----------------------------------------+
| Flight      | 20          | Approximate standard scenario field     |
| lines       |             | size.                                   |
+-------------+-------------+-----------------------------------------+
| Swath width | 60 ft.      | Typical. Does not greatly affect drift. |
+-------------+-------------+-----------------------------------------+
| Swath       | fine:       | Swath offset is good application        |
| d           | 0.6833      | practice. The value used results in 50% |
| isplacement |             | deposition at the edge of the field.    |
|             |             |                                         |
| fraction    |             |                                         |
| (as a       |             |                                         |
| fraction of |             |                                         |
| the swath   |             |                                         |
| width)      |             |                                         |
+-------------+-------------+-----------------------------------------+
| Drop size   | Fine (ASAE  | Dependent upon product.                 |
|             | definition) |                                         |
| D           |             |                                         |
| istribution |             |                                         |
+-------------+-------------+-----------------------------------------+
| Spray       | 50% water   | Dependent on tank mix. Calculate        |
| material    |             | nonvolatile rate based on the portion   |
|             | 50%         | of the tank mix which is not easily     |
|             | nonvolatile | evaporated (e.g. the fraction that is   |
|             |             | not water or high vapor pressure        |
|             |             | solvent).                               |
+-------------+-------------+-----------------------------------------+
| Wind speed  | 15 mph      | Typical wind speed varies greatly with  |
|             |             | geographic region and other factors.    |
| (at 2       |             | Ten mph is an adequate, high drift,     |
| meters      |             | input for many areas. Model runs for    |
| above the   |             | the plains states may require higher    |
| surface.    |             | wind speeds. Wind speed limitations     |
|             |             | 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  | Conservative input adequate for much of |
|             | F           | the US. Extreme values may              |
|             |             | significantly affect drift levels under |
|             |             | certain conditions.                     |
+-------------+-------------+-----------------------------------------+

+---------+-------------+-------------+------------------+-------------+
| []{     |             |             |                  |             |
| #__RefH |             |             |                  |             |
| eading_ |             |             |                  |             |
| __Toc19 |             |             |                  |             |
| 1187634 |             |             |                  |             |
| .ancho  |             |             |                  |             |
| r}Table |             |             |                  |             |
| 20.     |             |             |                  |             |
| Es      |             |             |                  |             |
| timated |             |             |                  |             |
| per     |             |             |                  |             |
| centage |             |             |                  |             |
| of      |             |             |                  |             |
| sulfo   |             |             |                  |             |
| meturon |             |             |                  |             |
| methyl  |             |             |                  |             |
| spray   |             |             |                  |             |
| drift   |             |             |                  |             |
| from    |             |             |                  |             |
| ground  |             |             |                  |             |
| or      |             |             |                  |             |
| aerial  |             |             |                  |             |
| appli   |             |             |                  |             |
| cations |             |             |                  |             |
| at      |             |             |                  |             |
| various |             |             |                  |             |
| di      |             |             |                  |             |
| stances |             |             |                  |             |
| from a  |             |             |                  |             |
| treated |             |             |                  |             |
| field.  |             |             |                  |             |
+---------+-------------+-------------+------------------+-------------+
| **D     | **\[A\]     | **\[B\]     | **\[C\] Aerial   | **\[D\]     |
| istance | Ground      | Ground      | (following many  | Aerial**    |
| Down    | Application | Application | label            |             |
| Wind    | (low        | (high       | Re               | **(high-end |
| (       | boom)**     | boom)**     | commendations)** | exposure    |
| Feet)** |             |             |                  | 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        |
+---------+-------------+-------------+------------------+-------------+

+---------+-------------+-------------+--------------------+----------+
| []{     |             |             |                    |          |
| #__RefH |             |             |                    |          |
| eading_ |             |             |                    |          |
| __Toc19 |             |             |                    |          |
| 1187635 |             |             |                    |          |
| .ancho  |             |             |                    |          |
| r}Table |             |             |                    |          |
| 21.     |             |             |                    |          |
| Es      |             |             |                    |          |
| timated |             |             |                    |          |
| amount  |             |             |                    |          |
| of      |             |             |                    |          |
| sulfo   |             |             |                    |          |
| meturon |             |             |                    |          |
| methyl  |             |             |                    |          |
| spray   |             |             |                    |          |
| drift   |             |             |                    |          |
| from    |             |             |                    |          |
| ground  |             |             |                    |          |
| or      |             |             |                    |          |
| aerial  |             |             |                    |          |
| appli   |             |             |                    |          |
| cations |             |             |                    |          |
| at      |             |             |                    |          |
| various |             |             |                    |          |
| di      |             |             |                    |          |
| stances |             |             |                    |          |
| from a  |             |             |                    |          |
| field   |             |             |                    |          |
| treated |             |             |                    |          |
| with    |             |             |                    |          |
| the     |             |             |                    |          |
| maximum |             |             |                    |          |
| labeled |             |             |                    |          |
| rate of |             |             |                    |          |
| 0.375   |             |             |                    |          |
| lb      |             |             |                    |          |
| ai/A.   |             |             |                    |          |
+---------+-------------+-------------+--------------------+----------+
| **D     | **\[A\]     | **\[B\]     | **\[C\] Aerial     | **\[D\]  |
| istance | Ground      | Ground      | (following many    | Aerial** |
| Down    | Application | Application | label              |          |
| Wind    | (low        | (high       | Recommendations)** | **(      |
| (       | boom)**     | boom)**     |                    | high-end |
| Feet)** |             |             |                    | exposure |
|         |             |             |                    | sce      |
|         |             |             |                    | nario)** |
+---------+-------------+-------------+--------------------+----------+
|         | ***Lbs      | ***Lbs      | ***Lbs ai/A***     | ***Lbs   |
|         | ai/A***     | ai/A***     |                    | 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     | 0.0005      | 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 adjacent 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.

#### Residue Studies

Environmental residue studies can also provide 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

### Uncertainties and Limitations for this Exposure Assessment

#### Limitations In Knowledge Of Actual Use Patterns

Knowledge on the specific 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
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 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).

#### Variability In Sulfometuron Environmental Persistence

Sulfometuron methyl persistence is significantly 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 / sediments with a greater range of pH levels
and other soil properties. This is particularly true for the aerobic
soil and anaerobic aquatic metabolism studies.

#### Exposure To Sulfometuron Methyl Degradates

Limitations in environmental fate data for the degradates 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 the 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
additional data and exposure assessment specific to the degradates of
concern would be needed.

## ECOLOGICAL EFFECTS CHARACTERIZATION

In screening-level ecological risk assessments, the ecological effects
characterization describes the types of effects a pesticide 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 studies that are conducted (and
reviewed) according to OPP test guidelines. 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 sulfometuron 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
amphibians are tested, although data from reptiles and amphibians may be
available from the literature as reported in ECOTOX. In absence of such
data, the risk assessment assumes that avian and reptilian and
terrestrial-phase amphibian sensitivities to the chemical 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 reproduction data is particularly relevant to
sulfometuron methyl because some data suggest plant reproduction may be
more sensitive to sulfonylurea herbicide exposure compared to growth 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-submitted
studies of the acute, oral toxicity of end use product (Oust^®^) 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 non-target organisms are provided in
"APPENDIX H: Ecological Effects Data Summaries."

Toxicological information on the primary degradates of sulfometuron
methyl (e.g., pyrimidine amine, pyrimidine-ol, saccharin, sulfonamide)
appears 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 conducted 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 ecologically 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 pertain 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: Ecological 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** contains 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. This finding is
consistent with the mode of action of sulfometuron methyl (inhibition of
ALS) and is similar to toxicity findings from other sulfonylurea
herbicides.

  -------------------------------------------------------------------------------------------------------------------------
  []{#__RefHeading___Toc191187636                                                                          
  .anchor}Table 22. The Most                                                                               
  Sensitive Endpoints Used In The                                                                          
  Sulfometuron Methyl                                                                                      
  Screening-Level Risk Estimation.                                                                         
  --------------------------------- --------------- ------------ ------------ -------------- ------------- ----------------
  **Environment**                   **Taxa**        **Type of    **Type of    **Endpoint**   **Units**     **MRID**
                                                    Risk**       Endpoint**                                

  Aquatic                           Freshwater Fish Acute        LC~50~       \> 148         mg ai/L       435018-02

                                                    Chronic      NOAEC        Data gap                     ^(A)^

                                    Freshwater      Acute        EC~50~       \> 150         mg ai/L       435018-03
                                    Invertebrates                                                          

                                                    Chronic      NOAEC        97             mg ai/L       416728-06^(A)^

                                    Saltwater Fish  Acute        LC~50~       \> 45          mg ai/L       416728-03

                                    Saltwater       Acute        EC~50~       \> 38.2        mg ai/L       416728-04
                                    Invertebrates                                                          

                                    Plants          Non-Listed   EC~50~       0.48           µg ai/L       435385-03

                                                    Listed       NOAEC        0.21           µg ai/L       435385-03

  Terrestrial                       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)^

                                                    Listed       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 exceeded the EC~25~, as
discussed in the terrestrial effect characterization section.

### Aquatic Effects Characterization 

#### 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 tests 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 studies 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 (nominal) 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 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. These studies are classified as acceptable and
meet the guideline requirements for an acute toxicity study with warm
water and cold water fish.

+------+-------------+---+------+------+-------------------+--------+
| []{  |             |   |      |      |                   |        |
| #__R |             |   |      |      |                   |        |
| efHe |             |   |      |      |                   |        |
| adin |             |   |      |      |                   |        |
| g___ |             |   |      |      |                   |        |
| Toc1 |             |   |      |      |                   |        |
| 9118 |             |   |      |      |                   |        |
| 7637 |             |   |      |      |                   |        |
| .    |             |   |      |      |                   |        |
| anch |             |   |      |      |                   |        |
| or}T |             |   |      |      |                   |        |
| able |             |   |      |      |                   |        |
| 23.  |             |   |      |      |                   |        |
| Fr   |             |   |      |      |                   |        |
| eshw |             |   |      |      |                   |        |
| ater |             |   |      |      |                   |        |
| Fish |             |   |      |      |                   |        |
| A    |             |   |      |      |                   |        |
| cute |             |   |      |      |                   |        |
| Toxi |             |   |      |      |                   |        |
| city |             |   |      |      |                   |        |
| of   |             |   |      |      |                   |        |
| Sulf |             |   |      |      |                   |        |
| omet |             |   |      |      |                   |        |
| uron |             |   |      |      |                   |        |
| Met  |             |   |      |      |                   |        |
| hyl. |             |   |      |      |                   |        |
+======+=============+===+======+======+===================+========+
| *    | **Species** | * | **9  | **   | **MRID No.**      | *      |
| *Gui |             | * | 6-ho | Toxi |                   | *Study |
| deli |             | % | ur** | city | **Author/Year**   | Clas   |
| ne** |             | a |      | Ca   |                   | sifica |
|      |             | i | **LC | tego |                   | tion** |
|      |             | * | ~50~ | ry** |                   |        |
|      |             | * | (mg/ |      |                   |        |
|      |             |   | L)** |      |                   |        |
+------+-------------+---+------+------+-------------------+--------+
| 72-1 | Bluegill    | 9 | \>   | Pra  | 435018-01         | Acce   |
|      | sunfish     | 9 | 150  | ctic |                   | ptable |
|      |             | . |      | ally | Brown (1994a)     |        |
|      | *(Lepomis   | 6 |      |      |                   |        |
|      | ma          |   |      | n    |                   |        |
|      | crochirus)* |   |      | on-t |                   |        |
|      |             |   |      | oxic |                   |        |
+------+-------------+---+------+------+-------------------+--------+
| 72-1 | Rainbow     | 9 | \>   | Pra  | 435018-02         | Acce   |
|      | trout       | 9 | 148  | ctic |                   | ptable |
|      |             | . |      | ally | Brown (1994b)     |        |
|      | *(O         | 6 |      |      |                   |        |
|      | ncorhynchus |   |      | n    |                   |        |
|      | mykiss)*    |   |      | on-t |                   |        |
|      |             |   |      | oxic |                   |        |
+------+-------------+---+------+------+-------------------+--------+

#### 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 toxicity 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 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 therefore considered a necessary byproduct of
increasing the solubility of the test chemical. 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."

+------+-------------+---+------+------+-------------------+--------+
| []{  |             |   |      |      |                   |        |
| #__R |             |   |      |      |                   |        |
| efHe |             |   |      |      |                   |        |
| adin |             |   |      |      |                   |        |
| g___ |             |   |      |      |                   |        |
| Toc1 |             |   |      |      |                   |        |
| 9118 |             |   |      |      |                   |        |
| 7638 |             |   |      |      |                   |        |
| .    |             |   |      |      |                   |        |
| anch |             |   |      |      |                   |        |
| or}T |             |   |      |      |                   |        |
| able |             |   |      |      |                   |        |
| 24.  |             |   |      |      |                   |        |
| Fr   |             |   |      |      |                   |        |
| eshw |             |   |      |      |                   |        |
| ater |             |   |      |      |                   |        |
| Inve |             |   |      |      |                   |        |
| rteb |             |   |      |      |                   |        |
| rate |             |   |      |      |                   |        |
| A    |             |   |      |      |                   |        |
| cute |             |   |      |      |                   |        |
| Toxi |             |   |      |      |                   |        |
| city |             |   |      |      |                   |        |
| of   |             |   |      |      |                   |        |
| Sulf |             |   |      |      |                   |        |
| omet |             |   |      |      |                   |        |
| uron |             |   |      |      |                   |        |
| Met  |             |   |      |      |                   |        |
| hyl. |             |   |      |      |                   |        |
+======+=============+===+======+======+===================+========+
| *    | **Species** | * | **4  | **   | **MRID No.**      | *      |
| *Gui |             | * | 8-ho | Toxi |                   | *Study |
| deli |             | % | ur** | city | **Author/Year**   | Clas   |
| ne** |             | a |      | Ca   |                   | sifica |
|      |             | i | **LC | tego |                   | tion** |
|      |             | * | ~50~ | ry** |                   |        |
|      |             | * | (mg/ |      |                   |        |
|      |             |   | L)** |      |                   |        |
+------+-------------+---+------+------+-------------------+--------+
| 72-2 | Water flea  | 9 | \>   | Pra  | 435018-03         | Acc    |
|      |             | 9 | 150  | ctic |                   | eptabl |
|      | *(Daphnia   | . |      | ally | Brown (1994c)     | e^(1)^ |
|      | magna)*     | 6 |      |      |                   |        |
|      |             |   |      | N    |                   |        |
|      |             |   |      | on-t |                   |        |
|      |             |   |      | oxic |                   |        |
+------+-------------+---+------+------+-------------------+--------+
| ^    |             |   |      |      |                   |        |
| (1)^ |             |   |      |      |                   |        |
| recl |             |   |      |      |                   |        |
| assi |             |   |      |      |                   |        |
| fied |             |   |      |      |                   |        |
| as   |             |   |      |      |                   |        |
| ac   |             |   |      |      |                   |        |
| cept |             |   |      |      |                   |        |
| able |             |   |      |      |                   |        |
| for  |             |   |      |      |                   |        |
| this |             |   |      |      |                   |        |
| risk |             |   |      |      |                   |        |
| ass  |             |   |      |      |                   |        |
| essm |             |   |      |      |                   |        |
| ent, |             |   |      |      |                   |        |
| see  |             |   |      |      |                   |        |
| APPE |             |   |      |      |                   |        |
| NDIX |             |   |      |      |                   |        |
| H:   |             |   |      |      |                   |        |
| Ec   |             |   |      |      |                   |        |
| olog |             |   |      |      |                   |        |
| ical |             |   |      |      |                   |        |
| Eff  |             |   |      |      |                   |        |
| ects |             |   |      |      |                   |        |
| Data |             |   |      |      |                   |        |
| S    |             |   |      |      |                   |        |
| umma |             |   |      |      |                   |        |
| ries |             |   |      |      |                   |        |
| for  |             |   |      |      |                   |        |
| deta |             |   |      |      |                   |        |
| ils. |             |   |      |      |                   |        |
+------+-------------+---+------+------+-------------------+--------+

#### Estuarine and marine Fish, Acute

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 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 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 these deficiencies
could render the study classification 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 EECs (i.e., a maximum peak concentration of 0.031 ppm in water,
Table 15), the bioavailable (dissolved) portion sulfometuron methyl
would have to be approximately [1500-fold lower]{.underline} 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.

+------+-------------+---+------+------+-----------------+----------+
| []{  |             |   |      |      |                 |          |
| #__R |             |   |      |      |                 |          |
| efHe |             |   |      |      |                 |          |
| adin |             |   |      |      |                 |          |
| g___ |             |   |      |      |                 |          |
| Toc1 |             |   |      |      |                 |          |
| 9118 |             |   |      |      |                 |          |
| 7639 |             |   |      |      |                 |          |
| .    |             |   |      |      |                 |          |
| anch |             |   |      |      |                 |          |
| or}T |             |   |      |      |                 |          |
| able |             |   |      |      |                 |          |
| 25.  |             |   |      |      |                 |          |
| Estu |             |   |      |      |                 |          |
| arin |             |   |      |      |                 |          |
| e/Ma |             |   |      |      |                 |          |
| rine |             |   |      |      |                 |          |
| Fish |             |   |      |      |                 |          |
| A    |             |   |      |      |                 |          |
| cute |             |   |      |      |                 |          |
| Toxi |             |   |      |      |                 |          |
| city |             |   |      |      |                 |          |
| of   |             |   |      |      |                 |          |
| Sulf |             |   |      |      |                 |          |
| omet |             |   |      |      |                 |          |
| uron |             |   |      |      |                 |          |
| Met  |             |   |      |      |                 |          |
| hyl. |             |   |      |      |                 |          |
+======+=============+===+======+======+=================+==========+
| *    | **Species** | * | **9  | **   | **MRID No.**    | **Study  |
| *Gui |             | * | 6-ho | Toxi |                 | Classifi |
| deli |             | % | ur** | city | **Author/Year** | cation** |
| ne** |             | a |      | Ca   |                 |          |
|      |             | i | **LC | tego |                 |          |
|      |             | * | ~50~ | ry** |                 |          |
|      |             | * | (mg/ |      |                 |          |
|      |             |   | L)** |      |                 |          |
+------+-------------+---+------+------+-----------------+----------+
| 72-3 | Sheepshead  | 9 | \>   | [\>] | 416728-03       | S        |
|      | minnow      | 9 | 45   | {.un |                 | upplemen |
|      |             | . |      | derl | Ward and Boeri  | tal^(1)^ |
|      | *           | 1 |      | ine} | (1990a)         |          |
|      | (Cyprinodon |   |      | Slig |                 |          |
|      | v           |   |      | htly |                 |          |
|      | ariegatus)* |   |      |      |                 |          |
|      |             |   |      | t    |                 |          |
|      |             |   |      | oxic |                 |          |
+------+-------------+---+------+------+-----------------+----------+
| ^    |             |   |      |      |                 |          |
| (1)^ |             |   |      |      |                 |          |
| Recl |             |   |      |      |                 |          |
| assi |             |   |      |      |                 |          |
| fied |             |   |      |      |                 |          |
| as   |             |   |      |      |                 |          |
| supp |             |   |      |      |                 |          |
| leme |             |   |      |      |                 |          |
| ntal |             |   |      |      |                 |          |
| for  |             |   |      |      |                 |          |
| the  |             |   |      |      |                 |          |
| purp |             |   |      |      |                 |          |
| oses |             |   |      |      |                 |          |
| of   |             |   |      |      |                 |          |
| this |             |   |      |      |                 |          |
| risk |             |   |      |      |                 |          |
| ass  |             |   |      |      |                 |          |
| essm |             |   |      |      |                 |          |
| ent. |             |   |      |      |                 |          |
| See  |             |   |      |      |                 |          |
| APPE |             |   |      |      |                 |          |
| NDIX |             |   |      |      |                 |          |
| H:   |             |   |      |      |                 |          |
| Ec   |             |   |      |      |                 |          |
| olog |             |   |      |      |                 |          |
| ical |             |   |      |      |                 |          |
| Eff  |             |   |      |      |                 |          |
| ects |             |   |      |      |                 |          |
| Data |             |   |      |      |                 |          |
| S    |             |   |      |      |                 |          |
| umma |             |   |      |      |                 |          |
| ries |             |   |      |      |                 |          |
| for  |             |   |      |      |                 |          |
| ad   |             |   |      |      |                 |          |
| diti |             |   |      |      |                 |          |
| onal |             |   |      |      |                 |          |
| s    |             |   |      |      |                 |          |
| tudy |             |   |      |      |                 |          |
| deta |             |   |      |      |                 |          |
| ils. |             |   |      |      |                 |          |
+------+-------------+---+------+------+-----------------+----------+

#### 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 the 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 mg 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 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 concentration
of 0.031 ppm in water, Table 15)**,** the bioavailable (dissolved)
portion sulfometuron methyl would have to be approximately [1300-fold
lower]{.underline} 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 the risk
assessment conclusions.

+------+-------------+---+------+------+----------------+-----------+
| []{  |             |   |      |      |                |           |
| #__R |             |   |      |      |                |           |
| efHe |             |   |      |      |                |           |
| adin |             |   |      |      |                |           |
| g___ |             |   |      |      |                |           |
| Toc1 |             |   |      |      |                |           |
| 9118 |             |   |      |      |                |           |
| 7640 |             |   |      |      |                |           |
| .    |             |   |      |      |                |           |
| anch |             |   |      |      |                |           |
| or}T |             |   |      |      |                |           |
| able |             |   |      |      |                |           |
| 26.  |             |   |      |      |                |           |
| Fr   |             |   |      |      |                |           |
| eshw |             |   |      |      |                |           |
| ater |             |   |      |      |                |           |
| Inve |             |   |      |      |                |           |
| rteb |             |   |      |      |                |           |
| rate |             |   |      |      |                |           |
| A    |             |   |      |      |                |           |
| cute |             |   |      |      |                |           |
| Toxi |             |   |      |      |                |           |
| city |             |   |      |      |                |           |
| of   |             |   |      |      |                |           |
| Sulf |             |   |      |      |                |           |
| omet |             |   |      |      |                |           |
| uron |             |   |      |      |                |           |
| Met  |             |   |      |      |                |           |
| hyl. |             |   |      |      |                |           |
+======+=============+===+======+======+================+===========+
| *    | **Species** | * | **9  | **   | **MRID No.**   | **Study   |
| *Gui |             | * | 6-ho | Toxi |                | Classif   |
| deli |             | % | ur** | city | *              | ication** |
| ne** |             | a |      | Ca   | *Author/Year** |           |
|      |             | i | **LC | tego |                |           |
|      |             | * | ~50~ | ry** |                |           |
|      |             | * | or   |      |                |           |
|      |             |   | 48-h |      |                |           |
|      |             |   | EC   |      |                |           |
|      |             |   | ~50~ |      |                |           |
|      |             |   | (mg/ |      |                |           |
|      |             |   | L)** |      |                |           |
+------+-------------+---+------+------+----------------+-----------+
| 72-3 | Mysid       | 9 | \>   | [\>] | 416728-04      | Sup       |
|      | shrimp^(1)^ | 9 | 44.8 | {.un |                | plemental |
|      |             | . |      | derl | Ward and Boeri | ^(2)^     |
|      | *           | 1 |      | ine} | (1990c)        |           |
|      | (Mysidopsis |   |      | Slig |                |           |
|      | bahia)*     |   |      | htly |                |           |
|      |             |   |      |      |                |           |
|      |             |   |      | t    |                |           |
|      |             |   |      | oxic |                |           |
+------+-------------+---+------+------+----------------+-----------+
| 72-3 | Eastern     | 9 | \>   | [\>] | 416728-05      | Suppleme  |
|      | oyster^(1)^ | 9 | 38.2 | {.un |                | ntal^(2)^ |
|      |             | . |      | derl | Ward and Boeri |           |
|      | *(          | 1 |      | ine} | (1990b)        |           |
|      | Crassostrea |   |      | Slig |                |           |
|      | virginica)* |   |      | htly |                |           |
|      |             |   |      |      |                |           |
|      |             |   |      | t    |                |           |
|      |             |   |      | oxic |                |           |
+------+-------------+---+------+------+----------------+-----------+
| ^    |             |   |      |      |                |           |
| (1)^ |             |   |      |      |                |           |
| 96-h |             |   |      |      |                |           |
| LC   |             |   |      |      |                |           |
| ~50~ |             |   |      |      |                |           |
| app  |             |   |      |      |                |           |
| lies |             |   |      |      |                |           |
| to   |             |   |      |      |                |           |
| mys  |             |   |      |      |                |           |
| ids; |             |   |      |      |                |           |
| 48-h |             |   |      |      |                |           |
| EC   |             |   |      |      |                |           |
| ~50~ |             |   |      |      |                |           |
| app  |             |   |      |      |                |           |
| lies |             |   |      |      |                |           |
| to   |             |   |      |      |                |           |
| oys  |             |   |      |      |                |           |
| ter. |             |   |      |      |                |           |
|      |             |   |      |      |                |           |
| ^    |             |   |      |      |                |           |
| (2)^ |             |   |      |      |                |           |
| Recl |             |   |      |      |                |           |
| assi |             |   |      |      |                |           |
| fied |             |   |      |      |                |           |
| as   |             |   |      |      |                |           |
| supp |             |   |      |      |                |           |
| leme |             |   |      |      |                |           |
| ntal |             |   |      |      |                |           |
| for  |             |   |      |      |                |           |
| the  |             |   |      |      |                |           |
| purp |             |   |      |      |                |           |
| oses |             |   |      |      |                |           |
| of   |             |   |      |      |                |           |
| this |             |   |      |      |                |           |
| risk |             |   |      |      |                |           |
| ass  |             |   |      |      |                |           |
| essm |             |   |      |      |                |           |
| ent. |             |   |      |      |                |           |
| See  |             |   |      |      |                |           |
| APPE |             |   |      |      |                |           |
| NDIX |             |   |      |      |                |           |
| H:   |             |   |      |      |                |           |
| Ec   |             |   |      |      |                |           |
| olog |             |   |      |      |                |           |
| ical |             |   |      |      |                |           |
| Eff  |             |   |      |      |                |           |
| ects |             |   |      |      |                |           |
| Data |             |   |      |      |                |           |
| S    |             |   |      |      |                |           |
| umma |             |   |      |      |                |           |
| ries |             |   |      |      |                |           |
| for  |             |   |      |      |                |           |
| ad   |             |   |      |      |                |           |
| diti |             |   |      |      |                |           |
| onal |             |   |      |      |                |           |
| s    |             |   |      |      |                |           |
| tudy |             |   |      |      |                |           |
| deta |             |   |      |      |                |           |
| ils. |             |   |      |      |                |           |
+------+-------------+---+------+------+----------------+-----------+

#### Freshwater Fish, Chronic

No acceptable or supplemental data on the chronic toxicity of
sulfometuron 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.

#### Freshwater Invertebrate, Chronic

The chronic toxicity of sulfometuron methyl to freshwater invertebrates
is indicated by a 21-day life cycle test conducted on the water flea,
*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 concentrations were close to nominal concentrations (i.e.,
within 20%), thus indicating that variability in test concentrations was
well within the acceptable limits of 1.5X. Survival and growth (length)
were not affected at any test concentration. Reproduction, as measured
by the number of neonates produced/daphnid, was [not]{.underline}
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 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 requirements
for a chronic study using a freshwater invertebrate.

+-------------+----+-------------+------------+-----------+---------+
| []{#__Ref   |    |             |            |           |         |
| Heading___T |    |             |            |           |         |
| oc191187641 |    |             |            |           |         |
| .a          |    |             |            |           |         |
| nchor}Table |    |             |            |           |         |
| 27.         |    |             |            |           |         |
| Freshwater  |    |             |            |           |         |
| Aquatic     |    |             |            |           |         |
| I           |    |             |            |           |         |
| nvertebrate |    |             |            |           |         |
| Chronic     |    |             |            |           |         |
| Toxicity    |    |             |            |           |         |
| for         |    |             |            |           |         |
| S           |    |             |            |           |         |
| ulfometuron |    |             |            |           |         |
| Methyl.     |    |             |            |           |         |
+=============+====+=============+============+===========+=========+
| *           | *  | **21-day    | *          | **MRID    | **Study |
| *Species/** | *% | NOAEC /     | *Endpoints | No.**     | Cl      |
|             | ai | LOAEC       | Affected** |           | assific |
| **Static    | ** | (m          |            | **Author  | ation** |
| Renewal**   |    | g/L)^(1)^** |            | (Year)**  |         |
+-------------+----+-------------+------------+-----------+---------+
| Water flea  | 99 | 97 / \>97   | Re         | 416728-06 | Acc     |
|             | .1 |             | production |           | eptable |
| *(Daphnia   |    |             |            | Baer      |         |
| magna)*     |    |             |            | (1990)    |         |
+-------------+----+-------------+------------+-----------+---------+
| ^(1)^ NOAEC |    |             |            |           |         |
| and LOAEC   |    |             |            |           |         |
| were        |    |             |            |           |         |
| re-analyzed |    |             |            |           |         |
| as part of  |    |             |            |           |         |
| this risk   |    |             |            |           |         |
| assessment. |    |             |            |           |         |
| See         |    |             |            |           |         |
| Appendix H  |    |             |            |           |         |
| for         |    |             |            |           |         |
| additional  |    |             |            |           |         |
| study       |    |             |            |           |         |
| details.    |    |             |            |           |         |
+-------------+----+-------------+------------+-----------+---------+

#### Aquatic Animal Sublethal Effects: Formulated Product and Degradate Toxicity 

No signs of toxicity or sublethal effects were observed 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 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 ranging 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 LC~50~s (probit
analysis) were reported as follows:

+------------+--------+------------------+------------+---------------+
| *          | **Test | **48-h LC~50~    | **Classi   | **Reference** |
| *Species** | Chem   | (mg/L)**         | fication** |               |
|            | ical** |                  |            |               |
|            |        | **(95%           |            |               |
|            |        | confidence       |            |               |
|            |        | limits)**        |            |               |
+------------+--------+------------------+------------+---------------+
| *Diaptomus | O      | 1315 (1207-1524) | su         | Naqvi and     |
| sp.*       | ust^®^ |                  | pplemental | Hawkins       |
|            |        |                  |            | (1989)        |
|            | (\~93% |                  |            |               |
|            | ai)    |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Eucyclops |        | 1320 (1154-1536) |            |               |
| sp.*       |        |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Alonella  |        | 802 (475-928)    |            |               |
| sp.*       |        |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Cypria    |        | 2241 (1744-4517) |            |               |
| sp*        |        |                  |            |               |
+------------+--------+------------------+------------+---------------+

This study is classified as supplemental primarily because test
concentrations were not measured in the study and the field collected
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 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 adjusted to reflect
the percent active ingredient in the formulated product. 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 any
test treatment. However, review of this study indicates that it is
[unacceptable]{.underline} 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 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 to
[aquatic]{.underline} 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."

####  Field Studies

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

#### Aquatic Plants

Aquatic plant toxicity studies using the TGAI are required to establish
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 freshwater 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 toxicity
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 ug 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 indicate
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 problematic.

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 concentrations of 370 μg/L and 410 μg/L (i.e., the
maximum values calculated for sulfometuron methyl applied directly to a
6 inch deep pond. Measurements at test initiation and termination
indicate stability of sulfometuron methyl in the test solutions.

A tier 2 test was conducted on the freshwater blue-green algae,
*Anabaena flos-aquae,* at measured test concentrations ranging from 14
to180 μg/L. Measurements at test initiation and termination indicate
stability of sulfometuron methyl in the test solutions. An EC~50~ of
41.6 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, the 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 sensitive species
(green algae and duckweed) will be used to calculate risk quotients.

+-----------------+---+-----------+---------+---------------+---------+
| [               |   |           |         |               |         |
| ]{#__RefHeading |   |           |         |               |         |
| ___Toc191187642 |   |           |         |               |         |
| .anchor}Table   |   |           |         |               |         |
| 28. Non-target  |   |           |         |               |         |
| Aquatic Plant   |   |           |         |               |         |
| Toxicity for    |   |           |         |               |         |
| Sulfometuron    |   |           |         |               |         |
| Methyl.         |   |           |         |               |         |
+=================+===+===========+=========+===============+=========+
| **Species**     | * | **EC~50~/ | **En    | **MRID No.**  | **Study |
|                 | * | NOAEC**   | dpoints |               | Cl      |
|                 | % |           | Aff     | **Author      | assific |
|                 | a | *         | ected** | (Year)**      | ation** |
|                 | i | *(µg/L)** |         |               |         |
|                 | * |           |         |               |         |
|                 | * |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| **Vascular      |   |           |         |               |         |
| Species:        |   |           |         |               |         |
| Duckweed**      |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| Duckweed        | 9 | 0.48 /    | Frond   | 435385-03     | Acc     |
|                 | 5 | 0.21      | Co      |               | eptable |
| (*Lemna gibba*) | . |           | unt[^6] | Kannuck       |         |
|                 | 7 |           |         | (1995)        |         |
+-----------------+---+-----------+---------+---------------+---------+
| **Non-Vascular  |   |           |         |               |         |
| Species: Algae  |   |           |         |               |         |
| and Diatoms**   |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| Green Algae     | 9 | 4.6 /     | Cell    | 416801-02     | Acc     |
| ^(1)^           | 9 | 0.63      | Density |               | eptable |
|                 | . |           |         | Hobert (1990) |         |
| *(Selenastrum   | 1 |           |         |               |         |
| capricornutum)* |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| Blue-green      | 9 | 41.6 /    | Cell    | 435385-02     | Suppl   |
| Algae^(1)^      | 9 | \<14      | Density |               | emental |
|                 | . |           |         | Thompson      |         |
| (*A.            | 2 |           |         | (1994)        |         |
| flos-aquae*)    |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| Fresh Water     | 9 | \>370     | Cell    | 435385-02     | Acc     |
| Diatom ^(2)^    | 9 |           | Density |               | eptable |
|                 | . |           |         | Thompson      |         |
| (*Navicula      | 2 |           |         | (1994)        |         |
| pelliculosa*)   |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+
| Salt Water      | 9 | \>410     | Cell    | 435385-02     | Acc     |
| Diatom^(2)^     | 9 |           | Density |               | eptable |
|                 | . |           |         | Thompson      |         |
| (*Skeletonema   | 2 |           |         | (1994)        |         |
| costatum*)      |   |           |         |               |         |
+-----------------+---+-----------+---------+---------------+---------+

^(1)^ Tier II definitive test

^(2)^ Tier I screening test

### Terrestrial Effects Characterization

#### 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
duck (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 29). 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. Lack of acute oral toxicity to birds is consistent
with testing results from other sulfonylurea herbicides (e.g.,
flazasulfuron, rimsulfuron). The guideline requirement (71-1) is
fulfilled for an acute oral toxicity study with birds for sulfometuron
methyl and the study (Accession No. 245375) is classified as acceptable.

+--------------+---+---------+------+----------------------+--------+
| []{#__R      |   |         |      |                      |        |
| efHeading___ |   |         |      |                      |        |
| Toc191187643 |   |         |      |                      |        |
| .            |   |         |      |                      |        |
| anchor}Table |   |         |      |                      |        |
| 29. Avian    |   |         |      |                      |        |
| Acute Oral   |   |         |      |                      |        |
| Toxicity for |   |         |      |                      |        |
| Sulfometuron |   |         |      |                      |        |
| Methyl.      |   |         |      |                      |        |
+==============+===+=========+======+======================+========+
| **Species**  | * | **L     | **   | **Accession No.**    | **S    |
|              | * | D~50~** | Toxi |                      | tudy** |
|              | % |         | city | **Author (Year)**    |        |
|              | a | **(mg   | Ca   |                      | **Clas |
|              | i | ai/k    | tego |                      | sifica |
|              | * | g-bw)** | ry** |                      | tion** |
|              | * |         |      |                      |        |
+--------------+---+---------+------+----------------------+--------+
| Mallard duck | [ | \>4,650 | Pra  | 245375               | Acce   |
|              | \ |         | ctic |                      | ptable |
| *(Anas       | > |         | ally | Dudeck and Bristol   |        |
| pla          | ] |         |      | (1981)               |        |
| tyrhynchos)* | { |         | n    |                      |        |
|              | . |         | on-t |                      |        |
|              | u |         | oxic |                      |        |
|              | n |         |      |                      |        |
|              | d |         |      |                      |        |
|              | e |         |      |                      |        |
|              | r |         |      |                      |        |
|              | l |         |      |                      |        |
|              | i |         |      |                      |        |
|              | n |         |      |                      |        |
|              | e |         |      |                      |        |
|              | } |         |      |                      |        |
|              | 9 |         |      |                      |        |
|              | 3 |         |      |                      |        |
+--------------+---+---------+------+----------------------+--------+

Two dietary studies are required to establish the subacute dietary
toxicity of sulfometuron methyl to birds. The preferred test species are
mallard duck and bobwhite quail. The submitted data indicates that
sulfometuron methyl 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 (Table 30. There was no
mortality, 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.

+---------------+-----+----------+-------+------------------+--------+
| []{#_         |     |          |       |                  |        |
| _RefHeading__ |     |          |       |                  |        |
| _Toc191187644 |     |          |       |                  |        |
| .anchor}Table |     |          |       |                  |        |
| 30. Avian     |     |          |       |                  |        |
| Subacute      |     |          |       |                  |        |
| Dietary       |     |          |       |                  |        |
| Studies for   |     |          |       |                  |        |
| Sulfometuron  |     |          |       |                  |        |
| Methyl.       |     |          |       |                  |        |
+===============+=====+==========+=======+==================+========+
| **Species**   | **% | **8-Day  | **Tox | **MRID No.**     | *      |
|               | a   | LC~50~** | icity |                  | *Study |
|               | i** |          | Categ | **Author         | Clas   |
|               |     | **(mg    | ory** | (Year)**         | sifica |
|               |     | ai/kg    |       |                  | tion** |
|               |     | -diet)** |       |                  |        |
+---------------+-----+----------+-------+------------------+--------+
| Northern      | 9   | \>5,620  | P     | 246409 ^(1)^     | Acce   |
| bobwhite      | 5.2 |          | racti |                  | ptable |
| quail         |     |          | cally | Beavers and Fink |        |
|               |     |          |       | (1981)           |        |
| *(Colinus     |     |          | non-  |                  |        |
| virginianus)* |     |          | toxic |                  |        |
+---------------+-----+----------+-------+------------------+--------+
| Mallard duck  | 92  | \>4,600  | P     | 71414            | Acce   |
|               |     |          | racti |                  | ptable |
| *(Anas        |     |          | cally | Hazelton         |        |
| pl            |     |          |       | Laboratories Inc |        |
| atyrhynchos)* |     |          | non-  | (1980)           |        |
|               |     |          | toxic |                  |        |
+---------------+-----+----------+-------+------------------+--------+

^(1)^ Accession number.

#### Acute Effects on Mammals

Wild mammal testing is required by the Agency 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 (MRID 43089201; Table 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,
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 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 with lack of acute oral
toxicity observed with other sulfonylurea herbicides to rats (e.g.,
flazasulfuron). This study is considered acceptable and satisfies the
guideline requirement (81-1) for an acute toxicity study with mammals.

+-----------+---+------------+----------------+-----------+---------+
| []{#      |   |            |                |           |         |
| __RefHead |   |            |                |           |         |
| ing___Toc |   |            |                |           |         |
| 191187645 |   |            |                |           |         |
| .anc      |   |            |                |           |         |
| hor}Table |   |            |                |           |         |
| 31.       |   |            |                |           |         |
| Mammalian |   |            |                |           |         |
| Acute     |   |            |                |           |         |
| Toxicity  |   |            |                |           |         |
| for       |   |            |                |           |         |
| Sul       |   |            |                |           |         |
| fometuron |   |            |                |           |         |
| Methyl.   |   |            |                |           |         |
+===========+===+============+================+===========+=========+
| **        | * | **         | **Affected     | **MRID    | **T     |
| Species** | * | Toxicity** | Endpoints**    | No.**     | oxicity |
|           | % |            |                |           | Cat     |
|           | a |            |                | **Author  | egory** |
|           | i |            |                | (Year)**  |         |
|           | * |            |                |           |         |
|           | * |            |                |           |         |
+-----------+---+------------+----------------+-----------+---------+
| Rat       | \ | LD~50~ \>  | Survival,      | 43089201  | IV      |
|           | ~ | 5,000 mg   | weight gain,   |           |         |
| (Spragu   | 1 | ai/kg bw   | gross organ    | Dashiell  |         |
| e-Dawley) | 0 | (male      | pathology      | and       |         |
|           | 0 | s/females) |                | Sarver    |         |
|           |   |            |                | (1990)    |         |
+-----------+---+------------+----------------+-----------+---------+

#### 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 honeybee
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).

+-----------+---------+-----------+-------+---------------+----------+
| []{#      |         |           |       |               |          |
| __RefHead |         |           |       |               |          |
| ing___Toc |         |           |       |               |          |
| 191187646 |         |           |       |               |          |
| .anc      |         |           |       |               |          |
| hor}Table |         |           |       |               |          |
| 32.       |         |           |       |               |          |
| N         |         |           |       |               |          |
| on-Target |         |           |       |               |          |
| Insects - |         |           |       |               |          |
| Acute     |         |           |       |               |          |
| Contact   |         |           |       |               |          |
| Toxicity  |         |           |       |               |          |
| for       |         |           |       |               |          |
| Sul       |         |           |       |               |          |
| fometuron |         |           |       |               |          |
| Methyl.   |         |           |       |               |          |
+===========+=========+===========+=======+===============+==========+
| **        | **%     | *         | **Tox | **MRID No.**  | **Study  |
| Species** | ai**    | *LD~50~** | icity |               | Classifi |
|           |         |           | Categ | **Author      | cation** |
|           |         | **(µg     | ory** | (Year)**      |          |
|           |         | ai/bee)** |       |               |          |
+-----------+---------+-----------+-------+---------------+----------+
| Honey Bee | \~100   | \>100     | P     | 416728-10     | Ac       |
|           |         | (contact) | racti |               | ceptable |
| *(Apis    |         |           | cally | Hoxter and    |          |
| me        |         |           |       | Smith (1990)  |          |
| llifera)* |         |           | non-  |               |          |
|           |         |           | toxic |               |          |
+-----------+---------+-----------+-------+---------------+----------+

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.

#### 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 test 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.

#### 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, 100, 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 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 rabbits
because dose levels were not considered high enough to adequately assess
developmental toxicity.

+------+---+--------+--------------------------+----------+----------+
| []{  |   |        |                          |          |          |
| #__R |   |        |                          |          |          |
| efHe |   |        |                          |          |          |
| adin |   |        |                          |          |          |
| g___ |   |        |                          |          |          |
| Toc1 |   |        |                          |          |          |
| 9118 |   |        |                          |          |          |
| 7647 |   |        |                          |          |          |
| .    |   |        |                          |          |          |
| anch |   |        |                          |          |          |
| or}T |   |        |                          |          |          |
| able |   |        |                          |          |          |
| 33.  |   |        |                          |          |          |
| M    |   |        |                          |          |          |
| amma |   |        |                          |          |          |
| lian |   |        |                          |          |          |
| D    |   |        |                          |          |          |
| evel |   |        |                          |          |          |
| opme |   |        |                          |          |          |
| ntal |   |        |                          |          |          |
| Toxi |   |        |                          |          |          |
| city |   |        |                          |          |          |
| of   |   |        |                          |          |          |
| Sulf |   |        |                          |          |          |
| omet |   |        |                          |          |          |
| uron |   |        |                          |          |          |
| Me   |   |        |                          |          |          |
| thyl |   |        |                          |          |          |
| .    |   |        |                          |          |          |
+======+===+========+==========================+==========+==========+
| **S  | * | **     | **Toxicity^1^**          | **       | **A      |
| peci | * | Test** |                          | Affected | ccession |
| es** | % |        |                          | End      | No.**    |
|      | a | **     |                          | points** |          |
|      | i | Type** |                          |          | **Author |
|      | * |        |                          |          | (year)** |
|      | * |        |                          |          |          |
+------+---+--------+--------------------------+----------+----------+
| Ra   | 1 | D      | NOAEL = 300 mg ai/kg/day | None     | 78798    |
| bbit | 0 | evelop | (highest test dose)      |          |          |
|      | 0 | mental |                          |          | Serota   |
| (New |   |        | LOAEL \> 300 mg          |          | (1981)   |
| Zea  |   |        | ai/kg/day                |          |          |
| land |   |        |                          |          |          |
| Wh   |   |        |                          |          |          |
| ite) |   |        |                          |          |          |
+------+---+--------+--------------------------+----------+----------+

#### Terrestrial 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 toxicity
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 on 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).

Formulated pesticide products 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 available for one species of terrestrial animal (rat; Table 34).
Results from this study indicate that the formulated product
DPX-T5486-87 is practically 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
considered acceptable.

+-----------+---+------------+----------------+-----------+---------+
| []{#      |   |            |                |           |         |
| __RefHead |   |            |                |           |         |
| ing___Toc |   |            |                |           |         |
| 191187648 |   |            |                |           |         |
| .anc      |   |            |                |           |         |
| hor}Table |   |            |                |           |         |
| 34.       |   |            |                |           |         |
| Mammalian |   |            |                |           |         |
| Acute     |   |            |                |           |         |
| Toxicity  |   |            |                |           |         |
| to        |   |            |                |           |         |
| Sul       |   |            |                |           |         |
| fometuron |   |            |                |           |         |
| Methyl in |   |            |                |           |         |
| F         |   |            |                |           |         |
| ormulated |   |            |                |           |         |
| Product:  |   |            |                |           |         |
| DPX       |   |            |                |           |         |
| -T5486-87 |   |            |                |           |         |
+===========+===+============+================+===========+=========+
| **        | * | **         | **Affected     | **MRID    | **T     |
| Species** | * | Toxicity** | Endpoints**    | No.**     | oxicity |
|           | % |            |                |           | Cat     |
|           | a |            |                |           | egory** |
|           | i |            |                |           |         |
|           | * |            |                |           |         |
|           | * |            |                |           |         |
+-----------+---+------------+----------------+-----------+---------+
| Rat       | 7 | LD~50~ \>  | Survival,      | 44874103  | IV      |
|           | 4 | 5,000 mg   | weight gain,   |           |         |
| (Spragu   | % | ai/kg bw   | gross organ    |           |         |
| e-Dawley) |   | (male      | pathology      |           |         |
|           |   | s/females) |                |           |         |
+-----------+---+------------+----------------+-----------+---------+

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 indicates
they do not contain information on endpoints that are considered
ecologically relevant (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, biochemical
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."

#### Field Studies

Data from field studies of the effects of sulfometuron methyl on
terrestrial animals were 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).

####  Terrestrial Plants 

Terrestrial 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 species of at least four dicotyledonous families,
one species of 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 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. Depending 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 sensitive 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 (Table 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 of 0.375 lb ai/acre exceeds 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]{.underline} 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
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
value.

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. 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 comparison 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 test species is [not]{.underline} 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.

+----------+--------+--------------+---------+----------+-----------+
| []{#__R  |        |              |         |          |           |
| efHeadin |        |              |         |          |           |
| g___Toc1 |        |              |         |          |           |
| 91187649 |        |              |         |          |           |
| .anch    |        |              |         |          |           |
| or}Table |        |              |         |          |           |
| 35.      |        |              |         |          |           |
| Summary  |        |              |         |          |           |
| of Most  |        |              |         |          |           |
| S        |        |              |         |          |           |
| ensitive |        |              |         |          |           |
| Tier II  |        |              |         |          |           |
| Ter      |        |              |         |          |           |
| restrial |        |              |         |          |           |
| No       |        |              |         |          |           |
| n-target |        |              |         |          |           |
| Plant    |        |              |         |          |           |
| Seedling |        |              |         |          |           |
| E        |        |              |         |          |           |
| mergence |        |              |         |          |           |
| and      |        |              |         |          |           |
| Ve       |        |              |         |          |           |
| getative |        |              |         |          |           |
| Vigor    |        |              |         |          |           |
| Toxicity |        |              |         |          |           |
| Data for |        |              |         |          |           |
| Sulf     |        |              |         |          |           |
| ometuron |        |              |         |          |           |
| Methyl.  |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| **Most   | **EC   | **NOAEC/     | **End   | **MRID   | **Study   |
| S        | ~25~** | \[EC05\]\*** | point** | No.**    | Classif   |
| ensitive |        |              |         |          | ication** |
| S        | **(lb  | **(lb        | **Aff   | **Autho  |           |
| pecies** | a      | ai/A)**      | ected** | r/year** |           |
|          | i/A)** |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| **       |        |              |         |          |           |
| Seedling |        |              |         |          |           |
| Eme      |        |              |         |          |           |
| rgence** |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| ***Mon   |        |              |         |          |           |
| ocots*** |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| Sorghum  | 1.9 x  | 4.3 x 10     | shoot   | 4        | A         |
|          | 10     | ^-5\ (\*)^   | height  | 35385-01 | cceptable |
|          | ^-4^   |              |         |          |           |
|          |        |              |         | McKelvey |           |
|          |        |              |         | (1995)   |           |
+----------+--------+--------------+---------+----------+-----------+
| ***D     |        |              |         |          |           |
| icots*** |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| sugar    | 3.2 x  | 2.9 x 10     | shoot   |          | A         |
| beet     | 10     | ^-5^         | dry wt  |          | cceptable |
|          | ^-5^   |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| **Ve     |        |              |         |          |           |
| getative |        |              |         |          |           |
| Vigor**  |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| ***Mon   |        |              |         | 4        |           |
| ocots*** |        |              |         | 35385-01 |           |
|          |        |              |         |          |           |
|          |        |              |         | McKelvey |           |
|          |        |              |         | (1995)   |           |
+----------+--------+--------------+---------+----------+-----------+
| Corn     | 3.7 x  | 9.9 x 10     | shoot   |          | A         |
|          | 10     | ^-7\ (\*)^   | dry wt  |          | cceptable |
|          | ^-5^   |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| ***D     |        |              |         |          |           |
| icots*** |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| Soybean  | 1.8 x  | 8.4 x 10     | shoot   |          | A         |
|          | 10     | ^-6\ (\*)^   | dry wt  |          | cceptable |
|          | ^-5^   |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+
| \* The   |        |              |         |          |           |
| NOAEC    |        |              |         |          |           |
| value is |        |              |         |          |           |
| above or |        |              |         |          |           |
| equal to |        |              |         |          |           |
| the      |        |              |         |          |           |
| EC~25~   |        |              |         |          |           |
| or below |        |              |         |          |           |
| the      |        |              |         |          |           |
| lowest   |        |              |         |          |           |
| concen   |        |              |         |          |           |
| tration, |        |              |         |          |           |
| th       |        |              |         |          |           |
| erefore, |        |              |         |          |           |
| an       |        |              |         |          |           |
| EC~05~   |        |              |         |          |           |
| is used  |        |              |         |          |           |
| instead. |        |              |         |          |           |
+----------+--------+--------------+---------+----------+-----------+

# RISK CHARACTERIZATION  {#risk-characterization .Style-Heading-1-+-Left}

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.

## Risk Estimation - Integration of Exposure and Effects Data 

Risk characterization integrates EECs and toxicity estimates and
evaluates the likelihood 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 calculated 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 organisms. 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 action, endangered species may potentially be affected
through chronic exposure,

\(5\) **non-endangered plant risk** - potential for effects in
non-target (non-endangered) plants, and

\(6\) **endangered plant risk** -- potential for effects in endangered
plants.

Currently, 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 calculation of the corresponding RQs
and LOCs, are tabulated below:

  --------------------------------------------------------------------------
  []{#__RefHeading___Toc191187650                                  
  .anchor}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 Endangered 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                                                         
  --------------------------------------------------------------------------

+------------------------------+------------------------------+--------+
| []{                          |                              |        |
| #__RefHeading___Toc191187651 |                              |        |
| .anchor}Table 37. Risk       |                              |        |
| Presumptions for Terrestrial |                              |        |
| Animals.                     |                              |        |
+==============================+==============================+========+
| **Risk Presumption**         | **RQ**                       | *      |
|                              |                              | *LOC** |
+------------------------------+------------------------------+--------+
| Acute Risk                   | EEC^(1)^/LC~50~ or           | 0.5    |
|                              | LD~50~/sqft^(2)^ or          |        |
|                              | LD~50~/day^(3)^              |        |
+------------------------------+------------------------------+--------+
| Acute Restricted Use         | EEC/LC~50~ or LD~50~/sqft or | 0.2    |
|                              | LD~50~/day                   |        |
|                              |                              |        |
|                              | (or LD~50~ \< 50 mg/kg)      |        |
+------------------------------+------------------------------+--------+
| Acute Endangered Species     | EEC/LC~50~ or LD~50~/sqft or | 0.1    |
|                              | LD~50~/day                   |        |
+------------------------------+------------------------------+--------+
| Chronic Risk                 | EEC/NOAEC                    | 1      |
+------------------------------+------------------------------+--------+
| Acute Endangered Terrestrial | EEC^(4)^/LD~50~ ^(4)^        | 0.05   |
| Invertebrate                 |                              |        |
+------------------------------+------------------------------+--------+
| ^(1)^ EEC units are in ppm   |                              |        |
| diet                         |                              |        |
|                              |                              |        |
| ^(2)^ [mg/sqft]{.underline}  |                              |        |
|                              |                              |        |
| LD~50~ \* wt. of bird        |                              |        |
|                              |                              |        |
| ^(3)^ [mg of toxicant        |                              |        |
| consumed/day]{.underline}    |                              |        |
|                              |                              |        |
| LD~50~ \* wt. of bird        |                              |        |
|                              |                              |        |
| ^(4)^ EEC = ppm in small     |                              |        |
| insects; LD~50~ = ug/g bw    |                              |        |
| (ppm)                        |                              |        |
+------------------------------+------------------------------+--------+

+------------------------------+------------------------------+--------+
| []{                          |                              |        |
| #__RefHeading___Toc191187652 |                              |        |
| .anchor}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 Species           | EEC/EC~05~ or NOAEC          | 1      |
+------------------------------+------------------------------+--------+
| ^(1)^ EEC units in lbs       |                              |        |
| ai/acre                      |                              |        |
|                              |                              |        |
| ^(2)^ EEC units in µg/L or   |                              |        |
| mg/L in water                |                              |        |
+------------------------------+------------------------------+--------+

### Non-target Aquatic Animals and Plants 

A summary of the toxicity values used to derive risk quotients for
aquatic animals and plants is provided in Table 39 below.

+-----------------------------------------+-------+---------+---------+
| []{#__RefHeading___Toc191187653         |       |         |         |
| .anchor}Table 39. Endpoints Used for    |       |         |         |
| Estimating Risks of Sulfometuron Methyl |       |         |         |
| to Aquatic Animals and Plants.          |       |         |         |
|                                         |       |         |         |
| \(1\)                                   |       |         |         |
+-----------------------------------------+-------+---------+---------+
| **Organism Group**                      | **    | **      | **MRID  |
|                                         | Toxic | Units** | \#**    |
|                                         | ity** |         |         |
+-----------------------------------------+-------+---------+---------+
| Freshwater fish, LC~50~                 | \>    | mg ai/L | 43      |
|                                         | 148   |         | 5018-02 |
+-----------------------------------------+-------+---------+---------+
| Freshwater invertebrate EC~50~          | \>    | mg ai/L | 43      |
|                                         | 150   |         | 5018-03 |
+-----------------------------------------+-------+---------+---------+
| Marine/estuarine fish LC~50~            | \> 45 | mg ai/L | 41      |
|                                         |       |         | 6728-03 |
+-----------------------------------------+-------+---------+---------+
| Marine/estuarine invertebrate           | \> 38 | mg ai/L | 41      |
| (mollusk - oyster) EC~50~               |       |         | 6728-04 |
+-----------------------------------------+-------+---------+---------+
| Chronic freshwater fish NOAEC           | Data  |         |         |
|                                         | gap   |         |         |
+-----------------------------------------+-------+---------+---------+
| Chronic freshwater invertebrate NOAEC   | 97    | mg ai/L | 41      |
|                                         |       |         | 6728-06 |
+-----------------------------------------+-------+---------+---------+
| Aquatic nonvascular plants EC~50~/NOAEC | 4.6 / | µg ai/L | 41      |
|                                         | 0.63  |         | 6801-02 |
+-----------------------------------------+-------+---------+---------+
| Aquatic vascular plants EC~50~/NOAEC    | 0.48  | µg ai/L | 43      |
|                                         | /     |         | 5385-03 |
|                                         | 0.21  |         |         |
+-----------------------------------------+-------+---------+---------+
| ^(1)^ Details for each study are        |       |         |         |
| presented in earlier sections of this   |       |         |         |
| document and in APPENDIX H: Ecological  |       |         |         |
| Effects Data Summaries,                 |       |         |         |
+-----------------------------------------+-------+---------+---------+

#### Fish and Aquatic Invertebrates

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 bounding 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 LOCs* 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 these acute toxicity tests, the actual RQ values
clearly represent conservative estimates of acute risk to these species.

The lowest available chronic NOAEC in aquatic invertebrates is 97 mg/L
(97,000 ug/L). Compared to the highest 21-d EEC of 26 µg/L derived 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]{.underline} be determined from the sulfometuron
methyl toxicity database because a definitive LC~50~ or EC~50~ was not
established for any aquatic animals. Considering data for another
sulfonylurea 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 46220967; 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 estimated NOAEC of \>21 mg/L for sulfometuron methyl. Compared
to the 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 were 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 animals is further discussed in the
Risk Description (Section 4.2),

#### 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
concentrations) 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-vascular aquatic plants receiving pesticide
runoff/drift, indicating a potential risk to these species.

[]{#__RefHeading___Toc191187654 .anchor}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     **148 ^(c)^**    **49 ^(c)^**       **65 ^(d)^**         **6.7 ^(d)^**
  rate of 0.375 lbs ai/acre                                                          
  x 1 aerial application/                                                            
  yr) ^(a,b)^                                                                        
  -----------------------------------------------------------------------------------------------------

^(a)^ Based on a peak EEC of 31 ug/L derived from the TX rights of way
exposure scenario which yielded the highest EECs. Details 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 0.63µg ai/L for non-vascular
plants; acute toxicity thresholds (EC~50~) used for non-endangered
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.

^(d)^ indicates an exceedence of non-target (i.e., non-endangered)
Species Level of Concern (LOC); RQ \> 1.0.

### Non-target Terrestrial Animals 

A summary of the toxicity values used to derive risk quotients for
terrestrial animals is provided in Table 41 below.

  ------------------------------------------------------------------------
  []{#__RefHeading___Toc191187655                       
  .anchor}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       \>4,650        245375
  ai/kg-bw)                                             

  Bird LC~50~ (dietary-based, mg         \>4,600        71414
  ai/kg-diet)                                           

  Mammal LD~50~ (oral dose-based, mg     \>5,000        430892-01
  ai/kg-bw)                                             

  Honeybee LD~50~, µg ai/bee             \>100          416728-10

  Mammal chronic NOAEL (dose-based, mg   300^(b)^       78798 ^(c)^
  ai/kg-bw/day)                                         
  ------------------------------------------------------------------------

^(a)^ Details for each study are presented in earlier sections of this
document and in APPENDIX H: Ecological Effects Data Summaries.

^(c)^ Highest dose tested.

^(c)^ Accession number.

#### Birds, Acute Risks

The 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 (treated 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 \< 0.04.
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-based 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 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 potential for
acute risk to birds is discussed further in the Risk Description
(Section 4.2).

+--------------+-------------+-----------------+----------------------+
| []{#__R      |             |                 |                      |
| efHeading___ |             |                 |                      |
| Toc191187656 |             |                 |                      |
| .            |             |                 |                      |
| anchor}Table |             |                 |                      |
| 42. Upper    |             |                 |                      |
| Bound        |             |                 |                      |
| Kenaga,      |             |                 |                      |
| Acute Avian  |             |                 |                      |
| Dose-Based   |             |                 |                      |
| Risk         |             |                 |                      |
| Quotients    |             |                 |                      |
| (Bounding    |             |                 |                      |
| Analysis     |             |                 |                      |
| Only).       |             |                 |                      |
+--------------+-------------+-----------------+----------------------+
| **Size       | **Adjusted\ | **Short         |                      |
| Class\       | LD~50~**    | Grass^(1)^**    |                      |
| (grams)**    |             |                 |                      |
|              | **(mg       |                 |                      |
|              | ai/kg-bw)** |                 |                      |
+--------------+-------------+-----------------+----------------------+
|              |             | **EEC**         | **RQ^(2)^**          |
+--------------+-------------+-----------------+----------------------+
| 20           | \> 2414     | 102.5           | \< 0.04              |
+--------------+-------------+-----------------+----------------------+
| 100          | \> 3074     | 58.5            | \< 0.02              |
+--------------+-------------+-----------------+----------------------+
| 1000         | \> 4342     | 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.  |             |                 |                      |
+--------------+-------------+-----------------+----------------------+

+-----------------------------+-----------------+----------------------+
| []{#                        |                 |                      |
| __RefHeading___Toc191187657 |                 |                      |
| .anchor}Table 43. Upper     |                 |                      |
| Bound Kenaga, Subacute      |                 |                      |
| Dietary-Based Risk          |                 |                      |
| Quotients (Bounding         |                 |                      |
| Analysis Only).             |                 |                      |
+-----------------------------+-----------------+----------------------+
| **Dietary-based LC~50~**    | **Short         |                      |
|                             | Grass^(1)^**    |                      |
| **(mg ai/kg-diet)**         |                 |                      |
+-----------------------------+-----------------+----------------------+
|                             | **EEC^(2)^**    | **RQ**               |
+-----------------------------+-----------------+----------------------+
| \> 4600                     | 90.0            | \< 0.02              |
+-----------------------------+-----------------+----------------------+
| ^(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 details on   |                 |                      |
| the model inputs,           |                 |                      |
| calculations and output.    |                 |                      |
| Size class not used for     |                 |                      |
| dietary risk quotients.     |                 |                      |
+-----------------------------+-----------------+----------------------+

#### Birds, Chronic Risks

As described in Section 3.3, no acceptable chronic toxicity data were
available on the effects of sulfometuron methyl on birds. Therefore,
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.

#### Mammals, Acute Risks

The unadjusted, acute LD~50~ for mammals 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 can 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
grass food item) are compared to the size-class adjusted LD~50~ values,
the largest upper bound 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). "

+--------------+-------------+--------------+------------------------+
| []{#__R      |             |              |                        |
| efHeading___ |             |              |                        |
| Toc191187658 |             |              |                        |
| .            |             |              |                        |
| anchor}Table |             |              |                        |
| 44. Upper    |             |              |                        |
| Bound        |             |              |                        |
| Kenaga,      |             |              |                        |
| Acute        |             |              |                        |
| Mammalian    |             |              |                        |
| Dose-Based   |             |              |                        |
| Risk         |             |              |                        |
| Quotients    |             |              |                        |
| (Bounding    |             |              |                        |
| Analysis     |             |              |                        |
| Only).       |             |              |                        |
|              |             |              |                        |
| \(1\)        |             |              |                        |
+--------------+-------------+--------------+------------------------+
| **Size       | **Adjusted\ | **Short      |                        |
| Class\       | LD~50~**    | Grass^(1)^** |                        |
| (grams)**    |             |              |                        |
+--------------+-------------+--------------+------------------------+
|              |             | **EEC**      | **RQ^(2)^**            |
+--------------+-------------+--------------+------------------------+
| 15           | \> 10989    | 85.8         | \< 0.01                |
+--------------+-------------+--------------+------------------------+
| 35           | \> 8891     | 59.3         | \< 0.01                |
+--------------+-------------+--------------+------------------------+
| 1000         | \> 3846     | 13.8         | \< 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    |             |              |                        |
| \>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.  |             |              |                        |
+--------------+-------------+--------------+------------------------+

#### 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 size-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 TREX for the remainder of the
chronic mammalian 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 classes (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 style="width:100%;">
<colgroup>
<col style="width: 12%" />
<col style="width: 18%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 8%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 6%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="12"><span id="__RefHeading___Toc191187659"
class="anchor"></span>Table 45. Upper Bound Kenaga, Chronic Mammalian
Dose-Based Risk Quotients.</td>
</tr>
<tr class="even">
<td rowspan="3"><strong>Size Class<br />
(grams)</strong></td>
<td rowspan="3"><p><strong>Adjusted NOAEL<sup>(1)</sup></strong></p>
<p><strong>(mg ai/kg-bw/d)</strong></p></td>
<td colspan="10"><strong>EECs and RQs</strong></td>
</tr>
<tr class="odd">
<td colspan="2"><strong>Short Grass</strong></td>
<td colspan="2"><strong>Tall Grass</strong></td>
<td colspan="2"><strong>Broadleaf Plants/<br />
Small Insects</strong></td>
<td colspan="2"><strong>Fruits/Pods/<br />
Seeds/<br />
Large Insects</strong></td>
<td colspan="2"><strong>Granivore</strong></td>
</tr>
<tr class="even">
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
</tr>
<tr class="odd">
<td>15</td>
<td>1206.6</td>
<td>85.8</td>
<td>0.07</td>
<td>39.3</td>
<td>0.03</td>
<td>48.3</td>
<td>0.04</td>
<td>5.36</td>
<td>&lt;0.01</td>
<td>1.19</td>
<td>&lt;0.01</td>
</tr>
<tr class="even">
<td>35</td>
<td>976.3</td>
<td>59.3</td>
<td>0.06</td>
<td>27.2</td>
<td>0.03</td>
<td>33.4</td>
<td>0.03</td>
<td>3.71</td>
<td>&lt;0.01</td>
<td>0.82</td>
<td>&lt;0.01</td>
</tr>
<tr class="odd">
<td>1000</td>
<td>422.3</td>
<td>13.8</td>
<td>0.03</td>
<td>6.3</td>
<td>0.01</td>
<td>7.7</td>
<td>0.02</td>
<td>0.86</td>
<td>&lt;0.01</td>
<td>0.19</td>
<td>&lt;0.01</td>
</tr>
<tr class="even">
<td colspan="12"><sup>(1)</sup> RQs derived for different size classes
using unadjusted NOAEL of &gt;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.</td>
</tr>
</tbody>
</table>

  --------------------------------- --------- -------- --------- -------- ------------- -------- ----------------- --------
  []{#__RefHeading___Toc191187660                                                                                  
  .anchor}Table 46. Upper Bound                                                                                    
  Kenaga, Chronic Mammalian                                                                                        
  Dietary-Based Risk Quotients                                                                                     

  **NOAEC (ppm)**                   **EECs                                                                         
                                    and RQs**                                                                      

                                    **Short            **Tall             **Broadleaf            **Fruits/Pods/\   
                                    Grass**            Grass**            Plants/\               Seeds/\           
                                                                          Small                  Large Insects**   
                                                                          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" for details on                                                                                   
  the model inputs, calculations                                                                                   
  and output. Size class not used                                                                                  
  for dietary risk quotients                                                                                       
  --------------------------------- --------- -------- --------- -------- ------------- -------- ----------------- --------

#### Non-Target Terrestrial-phase Amphibians, Reptiles and Terrestrial Invertebrates 

In absence of taxa-specific data, EFED currently uses birds as
surrogates for terrestrial non-target terrestrial phase amphibians and
reptiles and fish 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. This 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]{.underline} 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 risks to these taxa is qualitatively
discussed in the Risk Description portion of this document (Section
4.2).

### Non-target Terrestrial Plants 

A summary of the toxicity values used to derive risk quotients for
terrestrial plants is provided in Table 47 below.

[]{#__RefHeading___Toc191187661 .anchor}Table 47. Summary of Selected
Endpoints from Terrestrial Plant Toxicity Studies of Sulfometuron Methyl

+--------------------------------+------------------+-----------------+
| **Organism Group**             | **Toxicity**     | **MRID \#**     |
|                                |                  |                 |
|                                | **(Lbs           |                 |
|                                | A.I./Acre)**     |                 |
+================================+==================+=================+
| Terrestrial monocots           | EC~25~ = 1.9 x   | 435385-01       |
| emergence, EC~25~, lbs ai/acre | 10^-4^           |                 |
|                                |                  |                 |
| EC~05~ or NOAEC, lbs ai/acre   | EC~05~ = 4.3 x   |                 |
|                                | 10^-5^           |                 |
+--------------------------------+------------------+-----------------+
| Terrestrial dicots emergence,  | EC~25~ = 3.2 x   | 435385-01       |
| EC~25~, lbs ai/acre            | 10^-5^           |                 |
|                                |                  |                 |
| EC~05~ or NOAEC, lbs ai/acre   | NOAEC = 2.9 x    |                 |
|                                | 10^-5^           |                 |
+--------------------------------+------------------+-----------------+
| Terrestrial monocots           | EC~25~ = 3.7 x   | 435385-01       |
| vegetative vigor, EC~25~, lbs  | 10^-5^           |                 |
| ai/acre                        |                  |                 |
|                                | EC~05~ = 8.4 x   |                 |
| EC~05~ or NOAEC, lbs ai/acre   | 10^-6^           |                 |
+--------------------------------+------------------+-----------------+
| Terrestrial dicots vegetative  | EC~25~ = 1.8 x   | 435385-01       |
| vigor, EC~25~, lbs ai/acre     | 10^-5^           |                 |
|                                |                  |                 |
| EC~05~ or NOAEC, lbs ai/acre   | EC~05~ = 9.9 x   |                 |
|                                | 10^-7^           |                 |
+--------------------------------+------------------+-----------------+

^a^ Details for each study are presented in earlier sections of this
document and in "APPENDIX H: Ecological Effects Data Summaries".

#### Non-Endangered and Endangered Plant Risks

*Table 48* presents 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
maximum 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 the LOCs 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 aerial 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 quotients for
non-target terrestrial plants may be underestimated. Bold indicates an
LOC exceedence in Table 48.

+-------------+----------------+-------+----------------+-------------+
| []{#__Ref   |                |       |                |             |
| Heading___T |                |       |                |             |
| oc191187662 |                |       |                |             |
| .a          |                |       |                |             |
| nchor}Table |                |       |                |             |
| 48. RQ      |                |       |                |             |
| Values For  |                |       |                |             |
| Plants In   |                |       |                |             |
| Dry And     |                |       |                |             |
| S           |                |       |                |             |
| emi-Aquatic |                |       |                |             |
| Areas       |                |       |                |             |
| Exposed To  |                |       |                |             |
| S           |                |       |                |             |
| ulfometuron |                |       |                |             |
| Methyl      |                |       |                |             |
| Through     |                |       |                |             |
| Runoff      |                |       |                |             |
| And/Or      |                |       |                |             |
| Spray       |                |       |                |             |
| Drift.      |                |       |                |             |
+-------------+----------------+-------+----------------+-------------+
| **Plant     | **Application  | **T   | **Semi-Aquatic | **Spray     |
| Type**      | Method**       | erres | Adjacent       | Drift**     |
|             |                | trial | Areas**        |             |
|             |                | Adj   |                |             |
|             |                | acent |                |             |
|             |                | Ar    |                |             |
|             |                | eas** |                |             |
+-------------+----------------+-------+----------------+-------------+
| **Non       |                |       |                |             |
| -endangered |                |       |                |             |
| Plant RQs   |                |       |                |             |
| ^a,b,d^**   |                |       |                |             |
+-------------+----------------+-------+----------------+-------------+
| Monocot     | ground spray   | **    | **1007**       | **101**     |
|             |                | 118** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Dicot       | ground spray   | **    | **5977**       | **208**     |
|             |                | 703** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Monocot     | Aerial         | **    | **1086**       | **507**     |
|             |                | 197** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Dicot       | Aerial         | **1   | **6445**       | **1042**    |
|             |                | 172** |                |             |
+-------------+----------------+-------+----------------+-------------+
| *           |                |       |                |             |
| *Endangered |                |       |                |             |
| Plant RQs   |                |       |                |             |
| ^a,c,d^**   |                |       |                |             |
+-------------+----------------+-------+----------------+-------------+
| Monocot     | ground spray   | **    | **4448**       | **446**     |
|             |                | 523** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Dicot       | ground spray   | **    | **6595**       | **3788**    |
|             |                | 776** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Monocot     | Aerial         | **    | **4797**       | **2232**    |
|             |                | 872** |                |             |
+-------------+----------------+-------+----------------+-------------+
| Dicot       | Aerial         | **1   | **7112**       | **18939**   |
|             |                | 293** |                |             |
+-------------+----------------+-------+----------------+-------------+
| ^a^Detailed |                |       |                |             |
| c           |                |       |                |             |
| alculations |                |       |                |             |
| for RQs and |                |       |                |             |
| TerrPlant   |                |       |                |             |
| (ver 1.2.2) |                |       |                |             |
| input and   |                |       |                |             |
| output are  |                |       |                |             |
| provided in |                |       |                |             |
| "APPENDIX   |                |       |                |             |
| D:          |                |       |                |             |
| Terrplant   |                |       |                |             |
| Sp          |                |       |                |             |
| readsheet." |                |       |                |             |
|             |                |       |                |             |
| ^b^         |                |       |                |             |
| Non         |                |       |                |             |
| -endangered |                |       |                |             |
| toxicity    |                |       |                |             |
| thresholds  |                |       |                |             |
| (EC~25~)    |                |       |                |             |
| are 1.9 x   |                |       |                |             |
| 10^-4^      |                |       |                |             |
| (seedling   |                |       |                |             |
| emergence,  |                |       |                |             |
| monocot),   |                |       |                |             |
| 3.2 x       |                |       |                |             |
| 10^-5^      |                |       |                |             |
| (seedling   |                |       |                |             |
| emergence,  |                |       |                |             |
| dicot), 3.7 |                |       |                |             |
| x 10^-5^    |                |       |                |             |
| (vegetative |                |       |                |             |
| vigor,      |                |       |                |             |
| monocot),   |                |       |                |             |
| 1.8 x       |                |       |                |             |
| 10^-5^      |                |       |                |             |
| (vegetative |                |       |                |             |
| vigor,      |                |       |                |             |
| dicot) lb   |                |       |                |             |
| ai/A.       |                |       |                |             |
|             |                |       |                |             |
| ^c^         |                |       |                |             |
| Endangered  |                |       |                |             |
| toxicity    |                |       |                |             |
| thresholds  |                |       |                |             |
| (NOAEC of   |                |       |                |             |
| EC~05~) are |                |       |                |             |
| 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). |                |       |                |             |
+-------------+----------------+-------+----------------+-------------+

### Use of Contaminated Irrigation Waters

The potential risk to plants when exposed to irrigation water
contaminated with sulfometuron 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 that non-target
plants are exposed to sulfometuron methyl directly through spray drift
from irrigation water. Details of the calculation 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.

+-----------------+-----------------+-----------------+-----------------+
| [               |                 |                 |                 |
| ]{#__RefHeading |                 |                 |                 |
| ___Toc191187663 |                 |                 |                 |
| .anchor}Table   |                 |                 |                 |
| 49. Risk        |                 |                 |                 |
| Quotients for   |                 |                 |                 |
| Non-target and  |                 |                 |                 |
| Endangered      |                 |                 |                 |
| Plants,         |                 |                 |                 |
| Resulting From  |                 |                 |                 |
| Exposure to     |                 |                 |                 |
| Sulfometuron    |                 |                 |                 |
| Methyl in       |                 |                 |                 |
| Irrigation      |                 |                 |                 |
| Water           |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| **Location**    | **Ground water  | **Risk          |                 |
|                 | and Surface     | Quotients:**    |                 |
|                 | Water EEC:      |                 |                 |
|                 | ^1,\ 2^**       | **Ground water  |                 |
|                 |                 | (GW) and        |                 |
|                 | **(lbs ai/A)**  | Surface Water   |                 |
|                 |                 | (SW)            |                 |
|                 |                 | Irrigation**    |                 |
+-----------------+-----------------+-----------------+-----------------+
|                 |                 | **Non-target    | **Endangered    |
|                 |                 | plants^3^**     | plants^3^**     |
|                 |                 |                 |                 |
|                 |                 | **(EEC/EC25)**  | **(EEC/NOAEC)** |
+-----------------+-----------------+-----------------+-----------------+
| Semi-aquatic    | Ground water:   | GW: 0.04        | GW: 0.76        |
| and terrestrial | 7.5 x 10^-7^    |                 |                 |
| areas adjacent  |                 | SW: **3.9**     | SW: 71          |
| to irrigated    | Surface water:  |                 |                 |
| fields          | 6.1 x 10^-5^    |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| ^1^ Estimated   |                 |                 |                 |
| EEC assumes 1   |                 |                 |                 |
| inch of         |                 |                 |                 |
| irrigation      |                 |                 |                 |
| water is        |                 |                 |                 |
| applied to the  |                 |                 |                 |
| target field,   |                 |                 |                 |
| 1% drift of     |                 |                 |                 |
| irrigated water |                 |                 |                 |
| containing      |                 |                 |                 |
| sulfometuron    |                 |                 |                 |
| methyl, and no  |                 |                 |                 |
| runoff of       |                 |                 |                 |
| irrigated       |                 |                 |                 |
| water. See      |                 |                 |                 |
| Appendix G for  |                 |                 |                 |
| details on      |                 |                 |                 |
| irrigation      |                 |                 |                 |
| exposure        |                 |                 |                 |
| calculations.   |                 |                 |                 |
|                 |                 |                 |                 |
| ^2^ EECs 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      |                 |                 |                 |
| vigor endpoint. |                 |                 |                 |
| Bold RQ         |                 |                 |                 |
| indicates       |                 |                 |                 |
| exceedence of   |                 |                 |                 |
| LOC of 1.0      |                 |                 |                 |
| (i.e., RQ \> 1) |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+

## RISK DESCRIPTION 

### 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 data. 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 13).

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. Risks of direct effects to aquatic
vascular and nonvascular plants are above the Agency's LOCs. However,
the assessment refutes the risk hypothesis regarding direct effects to
aquatic animals, suggesting that direct effects to aquatic animals are
unlikely. Although risk from direct toxicity to aquatic animals is not
indicated in this screening level assessment, the dependence of aquatic
animals on primary producers (plants) results in the potential for
indirect effects to aquatic animals.

#### Fish and Aquatic Invertebrates

The submitted acute toxicity data for aquatic species 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 values for fish and invertebrates indicates
that these 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 interpreted 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
aquatic 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 levels.

Therefore, it is concluded that acute risk to aquatic animals from
[direct effects]{.underline} 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 invertebrates and fish, the
PRZM/EXAMS 21-day EEC (26 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
an ACR across chemicals, 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. (2007)
report a 90^th^ percentile ACR of 80 across all chemicals, which if
applied to the freshwater fish LC~50~ of \> 148 mg/L, would yield an
estimated NOAEC of \> 2 mg/L. This value is still 100-fold higher than
the chronic 60-d EEC of 20 ug/L. This 90^th^ percentile 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]{.underline} in acute-to-chronic 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]{.underline} of
sulfometuron methyl appears unlikely.

[]{#__RefHeading___Toc191187670 .anchor}Figure 3. Chronic Toxicity of
Sulfonylurea Herbicides to Freshwater Fish

![](media/image3.wmf){width="6.002777777777778in"
height="4.102777777777778in"}

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 expected 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 search 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 methyl
is practically nontoxic to these aquatic invertebrate crustaceans.
Therefore, toxicity findings of the formulated product (Oust^®^) are
consistent with those using the technical grade active ingredient with
*Daphnia magna* (MRID 435018-03)*.*

#### Non-target Aquatic-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 effect 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 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 resorption, and (3) a 30-d exposure to evaluate 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. Sulfometuron 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 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 (24.9 mg ai/L). Solvent controls were not significantly
different from 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 ai/L. Results from the
14-d tail resorption study indicate a significant reduction in tail
resorption at 9.95 and 24.9 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 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, randomization 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 various treatments was not reported (solvent concentrations were
only reported for the stock solutions).

+-----+--------+-------+------------------+--------+----------+------+
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| 9). |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
| **  | **Test | **Exp | **Endpoint       | **     | **Study  | **Re |
| Spe | Chem   | osure | (Effect)**       | Effect | Classifi | f.** |
| cie | ical** | Durat |                  | L      | cation** |      |
| s** |        | ion** |                  | evel** |          |      |
|     |        |       |                  |        |          |      |
|     |        |       |                  | **(mg  |          |      |
|     |        |       |                  | a      |          |      |
|     |        |       |                  | i/L)** |          |      |
+-----+--------+-------+------------------+--------+----------+------+
| *X  | sulfom | 96-h  | LC~50~ (%        | \>     | Supp     | Fort |
| eno | eturon |       | mortality)       | 24.9   | lemental | et   |
| pus | methyl |       |                  |        |          | al.  |
| l   | (99.5% |       | NOAEC (%         | 24.9   |          | (1   |
| aev | ai)    |       | malformations)   | ^(a)^  |          | 999) |
| is* |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
|     |        | 14-d  | NOAEC (tail      | 0.995  |          |      |
|     |        |       | resorption)      |        |          |      |
|     |        |       |                  | 9.95   |          |      |
|     |        |       | LOAEC (tail      |        |          |      |
|     |        |       | resporption)     |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
|     |        | 30-d  | NOAEC (limb      | 24.    |          |      |
|     |        |       | deformation)     | 9^(a)^ |          |      |
+-----+--------+-------+------------------+--------+----------+------+
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| dy. |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+

Although results from the Fort et al (1999) study are not being used
quantitatively in this risk assessment, they 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
26 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.

[]{.mark}

#### Aquatic Plants 

Toxicity studies indicate that sulfometuron methyl is classified as
highly toxic to aquatic plants, and the RQ values (65-148 for vascular
plants; 6.7-49 for nonvascular plants) indicates the potential risk to
aquatic vascular and nonvascular plants is above the Agency's concern
level. The 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:

14-d Recovery 14-d Recovery:

[14-d Exposure Conc. Frond Count Inhibition Biomass
Inhibition]{.underline}

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 methyl was
phytotoxic to duckweed at concentrations of [\>]{.underline} 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). 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 average concentration) was compared to
available toxicity information. Results indicate that the 90-d average
concentration (16 ug/L; Table 15) derived from the exposure scenario
yielding the highest exposure concentrations still exceeds the 14-d
EC~50~ (0.48 ug/L) by a factor of 33 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 concentrations 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 later
in Section 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 solutions 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 combined shoot and root
length was observed at or above 0.01 mg/L (approximating 30% of the
controls). Although not conclusive, results 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
product can not be determined conclusively from comparison of these two
studies because study protocols differed substantially (e.g., exposure
duration, measurement endpoints).

[]{.mark}

#### Aquatic Toxicity of Sulfometuron Methyl Degradates

As discussed earlier in Section 3.3.1.7, no acceptable or supplemental
studies were available on the toxicity of the major sulfometuron methyl
degradates to aquatic organisms. To characterize the potential toxicity
of the major degradates of sulfometuron 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 relationships (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.

+--------------------+------------+---------+--------------+----------+
| []{#__RefHead      |            |         |              |          |
| ing___Toc191187665 |            |         |              |          |
| .anchor}Table 51.  |            |         |              |          |
| ECOSAR-predicted   |            |         |              |          |
| toxicity values    |            |         |              |          |
| for major          |            |         |              |          |
| degradates of      |            |         |              |          |
| sulfometuron       |            |         |              |          |
| methyl.            |            |         |              |          |
+--------------------+------------+---------+--------------+----------+
| **Degradate Name** | **ECOSAR   | **Org   | **Toxicity   | **       |
|                    | Class**    | anism** | Endpoint**   | Toxicity |
|                    |            |         |              | Value    |
|                    |            |         |              | (mg/L)** |
+--------------------+------------+---------+--------------+----------+
| 2-Hydroxy,         | Phenols    | Fish    | 96-h LC~50~  | 49       |
| 4,6-dimethyl       |            |         |              |          |
| pyrimidine         |            |         | 90-d Chronic | 0.31     |
|                    |            |         | Value        |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Daphnid | 48-h LC~50~  | 13       |
|                    |            |         |              |          |
|                    |            |         | 21-d Chronic | 5.3      |
|                    |            |         | Value        |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Green   | 96-h EC~50~  | 257      |
|                    |            | Algae   |              |          |
+--------------------+------------+---------+--------------+----------+
| 2-(Aminosulfonyl)  | Neutral    | Fish    | 96-h LC~50~  | 1        |
| benzoic acid       | organic    |         |              | 37,000\* |
|                    | acids      |         | 30-d Chronic |          |
|                    |            |         | Value        | 12,600   |
+--------------------+------------+---------+--------------+----------+
|                    |            | Daphnid | 48-h LC~50~  | 1        |
|                    |            |         |              | 28,000\* |
|                    |            |         | 16-d EC~50~  |          |
|                    |            |         |              | 2,620    |
+--------------------+------------+---------+--------------+----------+
|                    |            | Green   | 96-h EC~50~  | 70,676   |
|                    |            | Algae   |              |          |
+--------------------+------------+---------+--------------+----------+
| Saccharin          | Th         | Fish    | 96-h LC~50~  | 1.9      |
|                    | iazolinone |         |              |          |
|                    | (iso-)     |         | Chronic      | 0.14     |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Daphnid | 48-h LC~50~  | 1.6      |
|                    |            |         |              |          |
|                    |            |         | Chronic      | 0.057    |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Green   | 96-h EC~50~  | 0.41     |
|                    |            | Algae   |              |          |
+--------------------+------------+---------+--------------+----------+
| 2-(Aminosulfonyl)  | Esters     | Fish    | 96-h LC~50~  | 152      |
| benzoic acid,      |            |         |              |          |
| methyl ester       |            |         | Chronic      | 136      |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Daphnid | 48-h LC~50~  | 2,350    |
+--------------------+------------+---------+--------------+----------+
|                    |            | Green   | 96-h EC~50~  | 11.6     |
|                    |            | Algae   |              |          |
|                    |            |         | Chronic      | 8.7      |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
| 2-Pyrimidinamine,  | Aromatic   | Fish    | 96-h LC~50~  | 214      |
| 4,6-dimethyl       | amines     |         |              |          |
|                    |            |         | Chronic      | 0.93     |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Daphnid | 48-h LC~50~  | 1.6      |
|                    |            |         |              |          |
|                    |            |         | Chronic      | 0.042    |
|                    |            |         | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
|                    |            | Green   | Chronic      | 12.9     |
|                    |            | Algae   | Value\*\*    |          |
+--------------------+------------+---------+--------------+----------+
| \* predicted       |            |         |              |          |
| toxicity value may |            |         |              |          |
| exceed compound'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 evaluated, 2-(aminosulfonyl) benzoic acid was
predicted to be the least toxic, with 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-(aminosulfonyl) benzoic acid appears at least 5 orders of magnitude
greater than the EEC for sulfometuron methyl. While this assumption may
have uncertainty due to the potential differential environmental fate
characteristics of sulfometuron methyl and 2-(aminosulfonyl) benzoic
acid, it appears highly unlikely that such differences would span the 5
order of magnitude range between EECs and predicted toxicity values for
2-(aminosulfonyl) benzoic acid, thus suggesting that the potential
ecological risk to fish, daphnids and green algae associated with
2-(aminosulfonyl) benzoic acid would be highly unlikely.

**Predicted toxicity and risk characterization for the other
degradates**

**Effects on Fish.** With the remaining four degradates (2-hydroxy,
4,6-dimethyl pyrimidine, saccharin, 2-(aminosulfonyl) benzoic acid,
methyl ester, and 2-pyrimidinamine, 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 predicted
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
concentrations 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 daphnids, 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-hydroxy,
4,6-dimethyl pyrimidine, saccharin, 2-(aminosulfonyl) benzoic acid,
methyl ester, and 2-pyrimidinamine, 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 greater (1.6-2,350 mg/L). However, for two
degradates (saccharin and 2-pyrimidinamine, 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 EECs.

**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 degradates. 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.

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 likely not a dominant concern, with the possible
exception of chronic toxicity to freshwater invertebrates (daphnia) and
acute toxicity to algae.

[]{.mark}

[]{.mark}

### Risk to Terrestrial Animals

[]{.mark}

In the conceptual model, direct deposition, spray drift, root uptake,
sediment and water runoff water, 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-phase amphibians, reptiles, mammals, and plants) were
assessed based on modeled EECs and available toxicity data. As part of
this screening terrestrial risk assessment, exposure concentrations of
sulfometuron methyl to non-target terrestrial plants and animals 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 consumed 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
refinement 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 hypothesis 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, the assessment
refutes the risk hypothesis regarding direct effects to animals and
suggests that direct effects to terrestrial animals are unlikely.

#### Birds

Sulfometuron methyl is categorized as practically nontoxic 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 (LC~50~ \>5,620 mg/kg-diet and
\> 4,600 mg/kg-diet, respectively). 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
exposure to sulfometuron methyl (Section 4.1; Table 42 and Table 43).
This bounding analysis compared size class adjusted 'indefinite' 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 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 (where 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
acetolactate 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 chronic
avian toxicity data for sulfometuron methyl.

[]{#__RefHeading___Toc191187671 .anchor}Figure 4. Chronic Avian Toxicity
of Sulfonylurea Herbicides

![](media/image4.wmf){width="4.604166666666667in"
height="3.209722222222222in"}

Results from Figure 4 indicate that out of the 12 chronic avian NOAECs
examined 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 tribenuron methyl (MRID 43594201) and 28 mg
ai/kg-diet for prosulfuron (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 suggest that chronic toxicity to avian fauna is
not likely to be a dominant concern in this risk assessment, although it
cannot be discounted entirely since LOCs would be exceeded for 2 of the
9 herbicides evaluated.

#### Mammals

As observed for avian fauna, sulfometuron methyl is classified as
practically nontoxic on an acute basis to mammals. As described in
Section 4.1, a bounding analysis compared 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 values. Since the
acute RQs for all weight classes of mammals consuming all feed types are
\< 0.01 and less than the Agency LOCs (Table 44), acute risks from
direct effects of sulfometuron methyl on mammals is not expected 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 mammal (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.

#### Non-target Terrestrial-phase 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
evaluation 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 quotients
for terrestrial non-target invertebrates. However, submitted 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 methyl 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, potential risk to
terrestrial insects and invertebrates in treatment area is expected to
be minimal.

[]{.mark}

[]{.mark}

### Risk to Terrestrial Plants

#### 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
sensitive to sulfometuron methyl, with dicots appearing to 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 (NOAEC), the predicted EEC for combined drift
and runoff were 4800 and 7100 for 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
sulfonylurea 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 at risk from adverse effects of sulfometuron methyl at the modeled
application rate. Specifically, the range in EC25s between the least and
most sensitive plant 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 predicted
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 for 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.

#### 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 studies 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
species (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 (*Pseudotsuga menziesii*),
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 to 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
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
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 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 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 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 (*Pinus 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 fertilization levels.
Although this study was designed primarily to investigate the efficacy
of different weed control methods, the authors reported 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).

#### Contaminated Irrigation Water 

The potential risks to plants when exposed to irrigation water
contaminated with sulfometuron methyl were estimated for both ground
water and surface 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 water (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 irrigation 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 water derived from surface water sources exceed the
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.

### Refined Spray Drift Analysis

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 potential
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 case assumptions regarding
potential exposure conditions (labeled A through D in Table 20 and Table
21).

+-----------+-------------+----------+---------------+---------------+
| []{#      |             |          |               |               |
| __RefHead |             |          |               |               |
| ing___Toc |             |          |               |               |
| 191187666 |             |          |               |               |
| .anc      |             |          |               |               |
| hor}Table |             |          |               |               |
| 52. Risks |             |          |               |               |
| to        |             |          |               |               |
| Te        |             |          |               |               |
| rrestrial |             |          |               |               |
| Plants    |             |          |               |               |
| from      |             |          |               |               |
| Spray     |             |          |               |               |
| Drift     |             |          |               |               |
| According |             |          |               |               |
| to        |             |          |               |               |
| Distance  |             |          |               |               |
| Downwind, |             |          |               |               |
| Ap        |             |          |               |               |
| plication |             |          |               |               |
| Method,   |             |          |               |               |
| and Drift |             |          |               |               |
| Exposure  |             |          |               |               |
| C         |             |          |               |               |
| onditions |             |          |               |               |
+-----------+-------------+----------+---------------+---------------+
| *         | **PERCENT   | **eec    | **n           | **endangered  |
| *Distance | OF          | ^(1)^**  | on-endangered | plants^(3)^** |
| Down Wind | APPLICATION |          | plants        |               |
| (Feet)**  | RATE**      |          | ^(2)^**       |               |
+-----------+-------------+----------+---------------+---------------+
|           | **          | ***lb    | ***RQ***      | ***RQ***      |
|           | *Percent*** | ai/A***  |               |               |
+-----------+-------------+----------+---------------+---------------+
| **\[A\]   |             |          |               |               |
| Ground    |             |          |               |               |
| Ap        |             |          |               |               |
| plication |             |          |               |               |
| (Low      |             |          |               |               |
| Boom)**   |             |          |               |               |
+-----------+-------------+----------+---------------+---------------+
| 0         | 102.0       | 0.3822   | **21233**     | **386061**    |
+-----------+-------------+----------+---------------+---------------+
| 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    |             |          |               |               |
| Ap        |             |          |               |               |
| plication |             |          |               |               |
| (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**       |
+-----------+-------------+----------+---------------+---------------+
| **\[C\]   |             |          |               |               |
| Aerial    |             |          |               |               |
| (         |             |          |               |               |
| Following |             |          |               |               |
| Many      |             |          |               |               |
| Label     |             |          |               |               |
| Recommend |             |          |               |               |
| ations)** |             |          |               |               |
+-----------+-------------+----------+---------------+---------------+
| 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  |             |          |               |               |
| Sc        |             |          |               |               |
| enario)** |             |          |               |               |
+-----------+-------------+----------+---------------+---------------+
| 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**      | **53232**     |
+-----------+-------------+----------+---------------+---------------+
| 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-e     |             |          |               |               |
| ndangered |             |          |               |               |
| plant RQs |             |          |               |               |
| based on  |             |          |               |               |
| v         |             |          |               |               |
| egetative |             |          |               |               |
| vigor     |             |          |               |               |
| EC25 for  |             |          |               |               |
| soybean   |             |          |               |               |
| of 1.8 x  |             |          |               |               |
| 10^-5^ lb |             |          |               |               |
| ai/A      |             |          |               |               |
| (MRID     |             |          |               |               |
| 4         |             |          |               |               |
| 35385-01) |             |          |               |               |
|           |             |          |               |               |
| ^(3)^     |             |          |               |               |
| E         |             |          |               |               |
| ndangered |             |          |               |               |
| plant RQs |             |          |               |               |
| based on  |             |          |               |               |
| v         |             |          |               |               |
| egetative |             |          |               |               |
| vigor     |             |          |               |               |
| EC05 for  |             |          |               |               |
| soybean   |             |          |               |               |
| of 9.9 x  |             |          |               |               |
| 10^-7^ lb |             |          |               |               |
| ai/A      |             |          |               |               |
| (MRID     |             |          |               |               |
| 43        |             |          |               |               |
| 5385-01). |             |          |               |               |
+-----------+-------------+----------+---------------+---------------+

Results from the refined spray drift modeling indicate that RQs exceed
the Agency 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 initial 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 ft) 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 applications, 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 ground applications. The EECs (and RQs) declined to 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
high 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]{.underline} 3 and 10 mph.

[]{.mark}

### Review of Incident Data

[]{.mark}

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 conclusions. 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, one 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 probable 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 of
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 pesticide 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 million.

**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 ground application, although
about one third of the incident reports did not contain information on
the application method. Relative to the type of application site, 7
involved railroad or road rights of way and 6 involved agriculture
sites. In terms of route 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 the 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.

### Overall Ecological Risk Conclusions

The results of this screening risk assessment indicate that potential
risks from 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 methyl 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 potential 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,
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
altered (i.e. reduced bird populations in edge 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 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.

### 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 determine 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 developed, sulfometuron methyl may be subjected to
additional screening and/or testing to better characterize effects
related to endocrine disruption.

### Federally Threatened and Endangered (Listed) Species

Both acute endangered species and chronic risk LOCs are 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.

#### Action Area 

For listed species assessment purposes, the action area is considered to
be the area potentially affected directly 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 those 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 to 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 action area is necessary.
Furthermore, RQs below the listed species LOCs for a given taxonomic
group indicate no concern for indirect effects upon listed species that
depend upon the taxonomic group covered by the RQ as a resource.
However, in situations where 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 considered 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 consider 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 direct
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 AgDRIFT 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 spray drift beyond 1000 feet the exceedances of levels
of concern for non-target plants are likely to extend well beyond 1000
feet given the trends observed with AgDRIFT up to 900 feet. This is
evident from the risk quotient calculations for terrestrial plants
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).

#### Taxonomic Groups Potentially at Risk

This 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 treated 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 LOCs 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 affected.
However, the Agency's LOC for endangered aquatic plants and terrestrial
plants is exceeded for the uses 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 performed 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
interpreted 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
default 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 achieved 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 individual 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.

+----------+------------+---------+----------------------+-------------+
| **Taxa** | **Probit   | **End   | **Estimated          | **Comment** |
|          | Slope**    | angered | Probability of an    |             |
|          |            | Species | Individual Effect at |             |
|          |            | LOC**   | the Endangered       |             |
|          |            |         | Species LOC**        |             |
+----------+------------+---------+----------------------+-------------+
| Fish     | 4.5 (2 --  | 0.05    | 1 in 4 x 10^8^       | Data        |
|          | 9)         |         |                      | i           |
|          |            |         | (1 in 2 x 10^2^ to 1 | nsufficient |
|          |            |         | in 2 x 10^31^)       | to allow    |
|          |            |         |                      | for probit  |
|          |            |         |                      | slope       |
|          |            |         |                      | derivation; |
|          |            |         |                      | therefore,  |
|          |            |         |                      | the default |
|          |            |         |                      | slope of    |
|          |            |         |                      | 4.5 with    |
|          |            |         |                      | lower and   |
|          |            |         |                      | upper       |
|          |            |         |                      | bounds of 2 |
|          |            |         |                      | -- 9 was    |
|          |            |         |                      | used.       |
+----------+------------+---------+----------------------+-------------+
| Aquatic  | 4.5 (2 --  | 0.05    | 1 in 4 x 10^8^       |             |
| Inver    | 9)         |         |                      |             |
| tebrates |            |         | (1 in 2 x 10^2^ to 1 |             |
|          |            |         | in 2 x 10^31^)       |             |
+----------+------------+---------+----------------------+-------------+
| Birds    | 4.5 (2 --  | 0.1     | 1 in 2.9x 10^5^ (1   |             |
|          | 9)         |         | in 44 to             |             |
|          |            |         |                      |             |
|          |            |         | 1 in 9 x 10^18^)     |             |
+----------+------------+---------+----------------------+-------------+
| Mammals  | 4.5 (2 --  | 0.1     | 1 in 2.9x 10^5^ (1   |             |
|          | 9)         |         | in 44 to             |             |
|          |            |         |                      |             |
|          |            |         | 1 in 9 x 10^18^)     |             |
+----------+------------+---------+----------------------+-------------+

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
actual exposure of sensitive species is likely to equal that modeled.
For birds, terrestrial-phase 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

Because 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 of 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 plant 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
refinement 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 terrestrial 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 chronic LOC. Similarly for fish, a chronic RQ, calculated from an
NOAEC estimated 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 unlikely. 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 non-endangered and endangered species
LOCs for non-target plants were exceeded for both terrestrial (monocots
and dicots) and aquatic plants (vascular, nonvascular) located adjacent
to treated areas, in semi-aquatic areas, and by spray drift for the
scenarios 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 pigmentation.

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 population. 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 addition,
depending on the severity of impacts to the plant community \[i.e.,
forest, wetlands, ecotones (edge and riparian habitats)\], assemblages
and ecosystem may be altered (i.e., reduced bird populations in edge
habitats, reduced riparian vegetation resulting 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 features (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 concern (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 terrestrial 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 elements 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 reviewed 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 Service(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 of 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 pesticide 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 the 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 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 biology 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.

**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 procedures 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 non-crop uses 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
potentially 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 biology 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.

  --------------------------------- ----------- --------------------- ------------ -------------------------
  []{#__RefHeading___Toc191187667                                                  
  .anchor}Table 53. Listed                                                         
  Taxonomic Groups Potentially at                                                  
  Risk from Direct or Indirect                                                     
  Effects of Sulfometuron Methyl                                                   
  Application for Vegetative                                                       
  Management Throughout the U.S.                                                   

  **Listed Taxon**                  **Direct    **Basis for Direct    **Indirect   **Basis for Indirect
                                    Effects**   Effects Concern**     Effects**    Effects Concern**

  Terrestrial and Semi-Aquatic      Yes         The endangered        Yes          Potential concerns from
  Plants -- monocots and dicots                 species LOC is                     shifts in plant community
                                                exceeded for                       structure and function
                                                terrestrial plants.                due to from selective
                                                                                   impacts on plant species.

  Terrestrial Invertebrates         No          Sulfometuron methyl   Yes          Potential concerns for
                                                is practically                     terrestrial invertebrates
                                                nontoxic to                        that use plants for
                                                honeybees, suggesting              habitat, feeding, or
                                                no direct effect                   cover requirements.
                                                concerns for                       
                                                terrestrial                        
                                                invertebrates.                     

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

  Terrestrial-phase Amphibians^(1)^ No          The LOC is not        Yes          Potential concerns for
                                                exceeded                           terrestrial-phase
                                                                                   amphibians that use
                                                                                   plants for habitat,
                                                                                   feeding, or cover
                                                                                   requirements.

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

  Aquatic Vascular Plants and       Yes         The endangered        No           Potential concerns from
  Nonvascular Plants                            species LOC is                     shifts in plant community
                                                exceeded for aquatic               structure and function
                                                vascular and                       due to from selective
                                                nonvascular plants.                impacts on plant species.

  Freshwater and Marine/Estuarine   No          The LOC is not        Yes          Potential concerns for
  fish and Aquatic-phase                        exceeded                           fish and aquatic-phase
  Amphibians^(2)^                                                                  amphibians that use
                                                                                   plants for habitat,
                                                                                   feeding, or cover
                                                                                   requirements.

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

  Mollusks                          No          The LOC is not        Yes          Potential concerns for
                                                exceeded                           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 fish and
aquatic-phase amphibian species are considered equivalent.

## Description of Assumptions, Limitations, Uncertainties, and Data Gaps

### Assumptions and Limitations Related to Effects on all Species

-   **Indirect Effects.** Perhaps one of the largest uncertainties
    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 present 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 altered (i.e. reduced
    bird populations in edge 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 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.

-   **Toxicity of Degradation Products.** In this screening level
    ecological risk assessment, 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 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
    were equivalent 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
    considered 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 species 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 substantially, 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
    tested). 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
    captured 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.

[]{.mark}

[]{.mark}

### Assumptions and Limitations Related to Effects 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
    additional acute toxicity data for marine and estuarine organisms
    because EECs were several orders of magnitude below reported
    toxicity limits. The freshwater chronic test with fathead minnow was
    found to be unacceptable, again because of uncertainty and
    variability 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 regarding
    the selection of the ACR, risks from direct effects of chronic
    sulfometuron methyl exposure to freshwater fish are not likely.

### Assumptions and Limitations Related to Effects on Terrestrial Species

-   **Study Quality and Data Gaps.** Lack of toxicity data was 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 methyl 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
    studies 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 be 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 Section 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 maximum application rate are well
    above a factor of 10, use of the lower application rates would not
    likely change the risk assessment conclusions.

# Literature Cited {#literature-cited .Style-Heading-1-+-Left}

Battaglin, WA, Furlongb, ET, Burkhardt, MR, Peter, CJ. 2000. Occurrence
of sulfonylurea, sulfonamide, imidazolinone, and other herbicides in
rivers, reservoirs and ground water in the Midwestern United States.
*Sci. Tot. Environ.* 248: 123-133

Blomquist, J.D., Denis, J.M., Hetrick, J.A., Jones, R.D., and
Birchfield, N.B. (2001) Pesticides in selected water-supply reservoirs
and finished drinking water, 1999-2000; summary of results from a pilot
monitoring program: U.S. Geological Survey Open-File Report 01-0456, 65
p. See: md.water.usgs.gov/nawqa/OFR_01-456.pdf .

Boyle, C and Walters, D. 2005. Induction of Systemic Protection Against
Rust Infection in Broad Bean by Saccharin: Effects on Plant Growth and
Development. *New Phytol.* 167: 607-612.

Bruce, RD and DJ Versteeg. 1992. A Statistical Procedure For Modeling
Continuous Toxicity Data. Env. Tox. and Chem. 11:1485-1494

Bureau of Land Management. 2005. Sulfometuron Methyl Ecological Risk
Assessment; Final Report. Bureau of Land Management Contract No.
NAD010156, Reno, NV. November.

Busse, MD, Fiddler, GO, and Ratcliff, AW. 2004. Ectomycorrhizal
Formation in Herbicide-Treated Soils of Differing Clay and Organic
Matter Content. *Water Air Soil Pollut.* 152: 23-34.

Byl, TD, Sutton, HD, and Klaine, SJ. 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.

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature
review and evaluation of the EPA food-chain (Kenaga) nomogram, an
instrument for estimating pesticide residues on plants. *Environ. Tox.
Chem*. 13:1383-1391.

Fletcher, JS, Pfleeger, TG, Ratsch, HC. 1993. Potential Environmental
Risks Associated With The New Sulfonylurea Herbicides. Environ. Sci.

Fort, DJ, Rogers, R, Copley, H, Bruning, L, Stover, EL, and Rapaport, D.
1999. Effect of Sulfometuron Methyl and Nicrosulfuron on Development and
Metamorphosis in Xenopus laevis: Impact of Purity. *Environ. Tox. Chem.*
18: 2934-2940.

McCall, P.J., R.L. Swann, and D.A. Laskowski. 1983. Partition Models for
Equilibrium Distribution of Chemicals in Environmental Compartments. In
R.L. Swann and A. Eschenroder (eds.). *Fate of Chemicals in the
Environment*. American Chemical Society. pp. 105-123.

McKelvey, RA. 1995. Influence of Sulfometuron Methyl (DPZ-T5648) on
Seedling Emergence and Vegetative Vigor of Several Terrestrial Plants.
Study No. AMR 2871-93. E.I. du Pont de Nemours and Co., Wilmington, DE
19880.

Naqvi, SM and Hawkins, RH 1989. Responses and LC50 Values for Selected
Microcrustaceans Exposed to Spartan, Malathion, Sonar, Weedtrine-D, and
Oust Pesticides. *Bull. Environ. Contam. Toxicol.* 43: 386-393.

Neary, DG, Conde, LF, and Smith, JE. 1984. Effects of Sulfometuron
Methyl on Six Important Competing Species in Coastal Plain Flatwoods.
*Proc.South Weed Sci.Soc.* 37: 193-199.

Raimondo, S, Montague, BJ, Barron, MG. (2007). Determinants of
Variability in Acute-Chronic Ratios for Invertebrates and Fish. Environ.
Tox. Chem. 26(9):

Romaire, RP. 1984. Acute Toxicity of Krenite and Oust to Juvenile Red
Swamp Crawfish, Procambarus clarkia. (Decapoda, Cambaridae). Louisiana
State University, Agricultural Experiment Station, Baton Rouge, LA.
Prepared for C.Wood, E.I. DuPont Corporation, Haskell Laboratory, New
Ark, Delaware. 19pp.

Teske, M.E and H.W. Thistle 2004. Aerial application model extension
into the far field. Biosystems Engineering 89(1) 29-36.

Thistle, HW, ME Teske, JG Droppo, CJ Allwine, SL Bird, and RJ Londergan.
2005.

AGDISP as a Source Term in Far Field Atmospheric Transport Modeling and
Near Field Geometric Assumptions. Amer. Soc. Agric. and Biol. Engineers,
St. Joseph, Michigan; [www.asabe.org](http://www.asabe.org/) .

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 Process 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~) using 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

Midwestern Rivers, Reservoirs, and Ground 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. Selective 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

# APPENDICES {#appendices .Style-Heading-1-+-Left}

# APPENDIX A: Structures and Chemical Names of Sulfometuron methyl Metabolites

+-----------------------------------+-----------------------------------+
| Chemical Structures               |                                   |
|                                   |                                   |
| Trivial or common names           |                                   |
|                                   |                                   |
| Company id or similar alternate   |                                   |
| names                             |                                   |
|                                   |                                   |
| Full chemical names               |                                   |
+-----------------------------------+-----------------------------------+
| ![](me                            | ![](media/image6.j                |
| dia/image5.jpeg){width="2.9375in" | peg){width="1.6972222222222222in" |
| height="1.7090277777777778in"}    | height="1.3993055555555556in"}    |
|                                   |                                   |
| Sulfometuron methyl               | Saccharin                         |
|                                   |                                   |
| DPX-T5648; DPX-5648; IN-T5648; IN | IN-581                            |
| T5648-18                          |                                   |
|                                   | 1,2-Benzisothiazol-3(2H)-one,     |
| Methyl                            | 1,1-dioxide                       |
| 2-(4,6-dimethylpyrimidi           |                                   |
| n-2-ylcarbamoylsulfamoyl)benzoate |                                   |
+-----------------------------------+-----------------------------------+
| ![](media/image7.j                | ![](media/image8.j                |
| peg){width="1.3472222222222223in" | peg){width="1.5416666666666667in" |
| height="1.375in"}                 | height="1.8194444444444444in"}    |
|                                   |                                   |
| Sulfometuron pyrimidine amine     | Sulfometuron sulfonamide          |
|                                   |                                   |
| IN-X0993; IN-X993; PA             | IN-D5803; SA; methyl              |
|                                   | phenylsulfonamide                 |
| 4,6-Dimethyl-2-pyrimidinamine     |                                   |
|                                   | Methyl 2-(aminosulfonyl)benzoate. |
| 4,6-dimethyl-2-pyrimidinamine     |                                   |
|                                   | 2-(Aminosulfonyl)-benzoic acid,   |
|                                   | methyl ester                      |
+-----------------------------------+-----------------------------------+
| ![](media/image9                  | ![](media/image10.                |
| .png){width="2.020138888888889in" | jpeg){width="2.688888888888889in" |
| height="1.8694444444444445in"}    | height="1.5583333333333333in"}    |
|                                   |                                   |
| Pyrimidine-ol                     | Sulfometuron free acid            |
|                                   |                                   |
| IN-11859                          | FA-SM; IN-T6385                   |
|                                   |                                   |
| 4,6-Dimethyl-2-pyrimidinol        | 2-\[\[\[\[(4,6                    |
|                                   | -Dimethyl-2-pyrimidinyl)amino\]ca |
|                                   | rbonyl\]amino\]sulfonyl\]-benzoic |
|                                   | acid                              |
+-----------------------------------+-----------------------------------+
| ![](media/image11.                |                                   |
| wmf){width="1.5868055555555556in" |                                   |
| height="1.875in"}                 |                                   |
|                                   |                                   |
| 0Free acid Sulfonamide            |                                   |
|                                   |                                   |
| FA-Sulfonamide; Free acid;        |                                   |
| IN-D5119                          |                                   |
|                                   |                                   |
| 2-(Aminosulfonyl)benzoic acid     |                                   |
+-----------------------------------+-----------------------------------+

# APPENDIX B: Environmental Fate Data Requirements

+---------+------------+----------+------+---------+---------+------+
| *       |            |          |      |         |         |      |
| *Enviro |            |          |      |         |         |      |
| nmental |            |          |      |         |         |      |
| Fate    |            |          |      |         |         |      |
| Data    |            |          |      |         |         |      |
| Requi   |            |          |      |         |         |      |
| rements |            |          |      |         |         |      |
| for     |            |          |      |         |         |      |
| Sulfo   |            |          |      |         |         |      |
| meturon |            |          |      |         |         |      |
| M       |            |          |      |         |         |      |
| ethyl** |            |          |      |         |         |      |
+=========+============+==========+======+=========+=========+======+
| **Guid  | **Data     | **Test   | **MR | **Study | **Data  | **   |
| eline** | Req        | Ma       | ID** | Cl      | Requ    | More |
|         | uirement** | terial** |      | assific | irement | Data |
|         |            |          |      | ation** | Met?**  | N    |
|         |            |          |      |         |         | eede |
|         |            |          |      |         |         | d?** |
+---------+------------+----------+------+---------+---------+------+
| \[      | Hydrolysis | sulf     | 4271 | Acc     | Yes     | No   |
| 161-1\] |            | ometuron | 5201 | eptable |         |      |
|         |            | methyl   |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Direct     | sulf     | 4218 | Acc     | Yes     | No   |
| 161-2\] | photolysis | ometuron | 2401 | eptable |         |      |
|         | in water   | methyl   |      |         |         |      |
|         |            |          | 4317 |         |         |      |
|         |            |          | 4101 |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Photolysis | sulf     | 4142 | Acc     | Yes     | No   |
| 161-3\] | on soil    | ometuron | 0601 | eptable |         |      |
|         |            | methyl   |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Photod     | NA       | NA   | not     | NA      | NA   |
| 161-4\] | egradation |          |      | r       |         |      |
|         | in Air     |          |      | equired |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Aerobic    | sulf     | 4209 | Acc     | Yes     | No   |
| 162-1\] | soil       | ometuron | 1401 | eptable |         |      |
|         | metabolism | methyl   |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Aerobic    | sulf     | 4317 | Acc     | Yes     | No   |
| 162-1\] | soil       | ometuron | 4102 | eptable |         |      |
|         | metabolism | methyl   | and  |         |         |      |
|         |            |          | 24   |         |         |      |
|         |            |          | 5375 |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Anaerobic  | NA       | NA   | ref     | Yes     | No   |
| 162-2\] | Soil       |          |      | 162-3   |         |      |
|         | Metabolism |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Anaerobic  | sulf     | 4209 | Acc     | Yes     | No   |
| 162-3\] | aquatic    | ometuron | 1402 | eptable |         |      |
|         | metabolism | methyl   | and  |         |         |      |
|         |            |          | 4318 |         |         |      |
|         |            |          | 8601 |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Anaerobic  | sulf     | 44   | Acc     | Yes     | No   |
| 162-3\] | aquatic    | ometuron | 1301 | eptable |         |      |
|         | metabolism | methyl   | 0-20 |         |         |      |
|         |            |          | (143 |         |         |      |
|         |            |          | 540) |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Aerobic    | sulf     | 4209 | Acc     | Yes     | No   |
| 162-4\] | aquatic    | ometuron | 1403 | eptable |         |      |
|         | metabolism | methyl   | and  |         |         |      |
|         |            |          | 4317 |         |         |      |
|         |            |          | 4103 |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | A          | sulf     | 4278 | Acc     | Yes     | No   |
| 163-1\] | dsorption/ | ometuron | 9301 | eptable |         |      |
|         |            | methyl   |      |         |         |      |
|         | Desorption |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | A          | Py       | 4278 | Acc     | Yes     | No   |
| 163-1\] | dsorption/ | rimidine | 9301 | eptable |         |      |
|         |            | amine    |      |         |         |      |
|         | Desorption |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | A          | s        | 4278 | Acc     | Yes     | No   |
| 163-1\] | dsorption/ | accharin | 9301 | eptable |         |      |
|         |            |          |      |         |         |      |
|         | Desorption |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Laboratory | NA       | NA   | not     | NA      | NA   |
| 163-2\] | Volatility |          |      | r       |         |      |
|         |            |          |      | equired |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Field      | NA       | NA   | not     | NA      | NA   |
| 163-3\] | Volatility |          |      | r       |         |      |
|         |            |          |      | equired |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | T          | Sulf     | 4321 | Acc     | Yes     | No   |
| 164-1\] | errestrial | ometuron | 2101 | eptable |         |      |
|         | Field      | methyl   | and  |         |         |      |
|         |            |          | 4363 |         |         |      |
|         | D          |          | 7101 |         |         |      |
|         | issipation |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Aquatic    | No study | NA   | NA      | NA      | NA   |
| 164-2\] | Field      |          |      |         |         |      |
|         | D          |          |      |         |         |      |
|         | issipation |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Forestry   | Sulf     | 4209 | Acc     | Yes     | No   |
| 164-3\] | D          | ometuron | 1404 | eptable |         |      |
|         | issipation | methyl   | and  |         |         |      |
|         |            |          | 4317 |         |         |      |
|         |            |          | 4104 |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Ac         | Waived   | NA   | NA      | NA      | NA   |
| 165-4\] | cumulation |          |      |         |         |      |
|         | in Fish    |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Ac         | Waived   | NA   | NA      | NA      | NA   |
| 165-5\] | cumulation |          |      |         |         |      |
|         | in aquatic |          |      |         |         |      |
|         | non-target |          |      |         |         |      |
|         | organism   |          |      |         |         |      |
|         | (crayfish) |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+
| \[      | Ground     | No Study | NA   | NA      | NA      | NA   |
| 166-1\] | Water-     | (not     |      |         |         |      |
|         | small      | r        |      |         |         |      |
|         |            | equired) |      |         |         |      |
|         | scale      |          |      |         |         |      |
|         | p          |          |      |         |         |      |
|         | rospective |          |      |         |         |      |
+---------+------------+----------+------+---------+---------+------+

# APPENDIX C: Ecological Aquatic Exposure 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                                                                                                                                           
  Exposure Durations -                                                                                                                                            
  Aerial application using                                                                                                                                        
  the Texas / Barton                                                                                                                                              
  Springs Salamander                                                                                                                                              
  scenario and Port Arthur                                                                                                                                        
  Texas meteorological                                                                                                                                            
  data.**                                                                                                                                                         

  **[DATE]{.underline}**   **[Peak]{.underline}**   **[96               **[21                **[60                **[90                **[Yearly]{.underline}**   **[30-Year]{.underline}**
                                                    hr]{.underline}**   Day]{.underline}**   Day]{.underline}**   Day]{.underline}**                              

  09-10                    49.472                   47.733              43.139               33.437               27.192               7.450                      4.065

  12-05                    36.060                   34.879              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

  19-10                    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               4.750                      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               12.818               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                    10.387                   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

  -------------------------- ------------------- ---------- -------------- ----------- -------- --------
  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 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          kbacs               76         days           Half-life             
  Metabolism                                                                                    

  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                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, monthly                        
                                                            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]{.underline}**   **[Peak]{.underline}**   **[96               **[21                **[60                **[90                **[Yearly]{.underline}**   **[30-Year]{.underline}**
                                                    hr]{.underline}**   Day]{.underline}**   Day]{.underline}**   Day]{.underline}**                              

  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                      1.582

  20-08                    25.924                   24.975              21.491               15.348               12.142               3.568                      1.734

  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-Legged 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

  09-09                    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

  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                    5.387               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:                                                                          
  Sfmt_CArway4_02-04                                                                   

  Metfile:             w94224.dvf                                                       

  PRZM scenario:       CArightofwayRLF.txt                                              

  EXAMS environment    pond298.exv                                                      
  file:                                                                                

  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   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      kbacw                 292        days               Half-life    
  Metabolism                                                                           

  Anaerobic Aquatic    kbacs                 76         days               Half-life    
  Metabolism                                                                           

  Aerobic Soil         asm                   61         days               Half-life    
  Metabolism                                                                           

  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          APPEFF                0.95       fraction                        
  Efficiency:                                                                          

  Spray Drift          DRFT                  0.05       fraction of                    
                                                        application rate               
                                                        applied to pond                

  Application Date     Date                  April 2    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.  IR                    EPA Pond                                   
  Run                                                                                  

  Flag for runoff      RUNOFF                none       none, monthly or                
  calc.                                                 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   1.300   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   0.570       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  0.20175
                                                      yearly      
                                                      averages:   
  --------------- ----------- ------- ------- ------- ----------- --------------

  ------------------ ----------------- ---------- -------------- ----------- -------- --------
  Output File:                                                                         
  Sfmt_FLcitrus1                                                                      

  Metfile:           w12844.dvf                                                        

  PRZM scenario:     FLcitrusSTD.txt                                                   

  EXAMS environment  pond298.exv                                                       
  file:                                                                               

  Chemical Name:     Sulfometuron                                                      
                     Methyl                                                           

  Description        Variable Name     Value      Units          Comments              

  Molecular weight   mwt               364.38     g/mol                                

  Henry\'s Law       henry                        atm-m\^3/mol                         
  Const.                                                                              

  Vapor Pressure     vapr              5.40E-16   torr                                 

  Solubility         sol               244        mg/L                                 

  Kd                 Kd                           mg/L                                 

  Koc                Koc               47.5       mg/L                                 

  Photolysis         kdp               0          days           Half-life             
  half-life                                                                           

  Aerobic Aquatic    kbacw             292        days           Half-life             
  Metabolism                                                                          

  Anaerobic Aquatic  kbacs             76         days           Half-life             
  Metabolism                                                                          

  Aerobic Soil       asm               61         days           Half-life             
  Metabolism                                                                          

  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      DEPI              4          cm                                   
  Depth:                                                                              

  Application Rate:  TAPP              0.42       kg/ha                                

  Application        APPEFF            0.95       fraction                             
  Efficiency:                                                                         

  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     IR                EPA Pond                                        
  Res. Run                                                                            

  Flag for runoff    RUNOFF            none       none, monthly                        
  calc.                                           or total                            
  ------------------ ----------------- ---------- -------------- ----------- -------- --------

**Florida Turf Scenario**

  ------------------------ -------- -------- -------- -------- ----------- ---------------
  **[Sorted                                                                
  results]{.underline}**                                                   

  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

  0.065                    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

  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       0.035

  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  0.046883
                                                               yearly      
                                                               averages:   
  ------------------------ -------- -------- -------- -------- ----------- ---------------

  --------------------- --------------- ---------- --------------- ----------- -------- --------
  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     pond298.exv                                                      
  file:                                                                                 

  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   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       kbacw           292        Days            Half-life             
  Metabolism                                                                            

  Anaerobic Aquatic     kbacs           109        Days            Half-life             
  Metabolism                                                                            

  Aerobic Soil          asm             61         Days            Half-life             
  Metabolism                                                                            

  Hydrolysis:           pH 5            8.8        Days            Half-life             

  Hydrolysis:           pH 7            139        Days            Half-life             

  Hydrolysis:           pH 9            224        Days            Half-life             

  Method:               CAM             1          integer         See PRZM              
                                                                   manual               

  Incorporation Depth:  DEPI            0          Cm                                    

  Application Rate:     TAPP            0.42       kg/ha                                 

  Application           APPEFF          0.99       fraction                              
  Efficiency:                                                                           

  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                                                

                        UPTKF                                                            

  Record 18:            PLVKRT                                                           

                        PLDKRT                                                           

                        FEXTRC          0.5                                              

  Flag for Index Res.   IR              EPA Pond                                         
  Run                                                                                   

  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           pond298.exv                                                       
  environment                                                                      
  file:                                                                            

  Chemical Name:  Sulfometuron                                                      
                  Methyl                                                           

  Description     Variable Name   Value      Units           Comments               

  Molecular       mwt             364.38     g/mol                                  
  weight                                                                           

  Henry\'s Law    henry                      atm-m\^3/mol                           
  Const.                                                                           

  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      kdp             0          Days            Half-life              
  half-life                                                                        

  Aerobic Aquatic kbacw           292        Days            Half-life              
  Metabolism                                                                       

  Anaerobic       kbacs           76         Days            Half-life              
  Aquatic                                                                          
  Metabolism                                                                       

  Aerobic Soil    asm             61         Days            Half-life              
  Metabolism                                                                       

  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   DEPI            4          cm                                     
  Depth:                                                                           

  Application     TAPP            0.42       kg/ha                                  
  Rate:                                                                            

  Application     APPEFF          0.95       fraction                               
  Efficiency:                                                                      

  Spray Drift     DRFT            0.05       fraction of                           
                                             application                           
                                             rate applied to                       
                                             pond                                  

  Application     Date            3-Jan      dd/mm or dd/mmm                       
  Date                                       or dd-mm or                           
                                             dd-mmm                                

  Record 17:      FILTRA                                                            

                  IPSCND          1                                                 

                  UPTKF                                                             

  Record 18:      PLVKRT                                                            

                  PLDKRT                                                            

                  FEXTRC          0.5                                               

  Flag for Index  IR              EPA Pond                                          
  Res. Run                                                                         

  Flag for runoff RUNOFF          none       none, monthly                         
  calc.                                      or                                    
                                             total(average                         
                                             of entire run)                        
  --------------- --------------- ---------- --------------- ----------- --------- --------------

# APPENDIX D: Terrplant Spreadsheet

(TerrPlant Version 1.2.2)

  ---------------------- ---------------- ---------------- ----------------
  **Table D-1. Chemical                                    
  Identity.**                                              

  **Chemical Name**      **Sulfometuron                    
                         Methyl**                          

  **PC code**            **122001**                        

  **Use**                **non-crop                        
                         vegetative                        
                         management,                       
                         forestry, rights                  
                         of way**                          

  **Application Method** **ground**                        

  **Application Form**   **water                           
                         dispersible                       
                         granule**                         

  **Solubility in Water  **244 (pH 7)**                    
  (ppm)**                                                  
  ---------------------- ---------------- ---------------- ----------------

  ---------------------- ---------------- ---------------- ----------------
  **Table D-2. Input                                       
  parameters used to                                       
  derive EECs.**                                           

  **Input 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                  (A/I)\*R\*10                0.1875
  areas                                                               

  **Spray drift**                         **A\*D**                    **0.00375**

  **Total for dry                         **((A/I)\*R)+(A\*D)**       **0.0225**
  areas**                                                             

  **Total for                             **((A/I)\*R\*10)+(A\*D)**   **0.19125**
  semi-aquatic areas**                                                
  ---------------------- ---------------- --------------------------- ----------------

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

                **Seedling                       **Vegetative      
                Emergence**                      Vigor**           

  **Plant       **EC25**          **NOAEC**      **EC25**          **NOAEC**
  type**                                                           

  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-aquatic                                                  
  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

  Dicot          listed            775.86    6594.83            3787.88

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

# APPENDIX E: Adverse Ecological Incidents Associated with Sulfometuron Methyl Use

  ---------------------------------------------------------------------------------------------------------------------------------------------------------
  Incident ID   Use Site        Start Date  Legality       Certainty   State   County      Year   Total         Appl. Rate Appl.     Affected   Product
                                                                                                  Magnitude                Method    Species    
  ------------- --------------- ----------- -------------- ----------- ------- ----------- ------ ------------- ---------- --------- ---------- -----------
  I011666-001   Municpal        01-Nov-00   Registered use Highly      ID                  2000   Thousands Of  1 Oz/Acre  Aerial    1          OUST
                operation                                  Probable                               Acres                                         

  I013086-001   Right-of-way,   15-Jun-02   Registered use Probable    WA      Kittitas    2002   Unknown       3 Oz Per   Spray     1          Oust
                rail                                                                                            15 Gallons                      

  I009556-043   Agricultural    15-May-92   Registered use Probable    CO      Costilla    1992   \$4,400,000   N/R        Spray     1          OUST
                area                                                                              Damages                                       

  I005972-001   PLANT SITE      01-Sep-97   Registered use Probable    TX                  1997                 N/A        N/R       1          OUST

  I006010-003   Utility plant   19-Aug-97   Misuse         Probable    MS                  1997   Unknown                  RUN-OFF   1          
                                            (accidental)                                                                                        

  I000903-005   Forest          01-Sep-91   Misuse         Probable    TX      Anderson    1991   N/R           500 Oz/    Spray     1          OUST
                                            (accidental)                                                        3000 Acres                      

  I000903-002   Agricultural    01-Jan-94   Registered use Probable    TX      Cherokee    1994   N/R           N/R        Spray     1          OUST
                area                                                                                                                            

  I006010-001   Right-of-way,   20-Aug-97   Misuse         Probable    LA                  1997   Unknown       N/R        N/R       1          
                road                        (accidental)                                                                                        

  I000903-003   Agricultural    01-Jan-94   Registered use Probable    TX                  1994   N/R           N/R        Spray     2,3,4      OUST
                Area                                                                                                                            

  I000903-001   Agricultural    01-Sep-91   Registered use Probable    TX      Anderson    1991   N/R           2 Oz/25-30 Spray     1          OUST
                area                                                                                            Gal Water                       

  I006010-002   Agricultural    20-Aug-97   Misuse         Probable    TX                  1997   Unknown       N/R        N/R       1          
                area                        (accidental)                                                                                        

  I007269-001   Agricultural    21-May-98   Registered use Probable    CA      Fresno      1998   All           N/R        N/R       1          OUST
                area                                                                                                                            

  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 Oz/Acre  Spray     1          Oust
                                                                                                                                                herbicide

  I015832-001   Right-of-way,   14-Dec-04   Registered use Probable    LA      Lafayette   2004                 N/R        Spray     1          Oust
                road                                                                                                                            

  I017481-001   Turf,           24-May-06   Undetermined   Probable    WI      Waukesha    2006   Unknown       Unknown    N/R       1          DuPont Oust
                residential                                                                                                                     

  I015576-001   Right-of-way,   01-Apr-04   Registered use Probable    OR      Multnomah   2004   \$40,000      N/R        N/R       1          Landmark MP
                road                                                                                                                            

  I016302-001   Right-of-way,   23-May-05   Registered use Probable    WA      Grant       2005   Less Than An  N/R        Spray     1          Oust
                road                                                                              Acre                                          

  I016429-001   Industrial site 13-Jun-05   Registered use Probable    WA      Grant       2005   \$90,000      5 Oz/Acre  Spray     1          Oust
                                                                                                  Damage                                        

  I015440-001   Right-of-way,   01-Jun-03   Misuse         Probable    MN      Benton      2003   2 Acres       5 Oz/Acre  Spray     1          Oust
                utility                     (accidental)                                                                                        

  I013194-001   Right-of-way,   02-Jul-02   Registered use Probable    ND      Walsh       2002   10 Acres      3 Oz/15    Spray     1          OUST
                rail                                                                                            Gals Water                      

  I014409-011   Right-of-way,   03-Jun-92   Registered use Possible    WA      Walla Walla 1992   Not Given                          1          
                road                                                                                                                            

  B000601-010   Right-of-way    25-May-84   Registered use Possible    CA      Fresno      1984   N/R                      Spray     1          Oust

  I015796-001   Right-of-way,   08-Nov-04   Registered use Possible    KY      Jessamine   2004   1-4 Acres     3 Oz/Acre  Nr        1          Oust XP
                utility                                                                                                                         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 Possible    SC      Saluda      1992   Numerous      N/R        N/R       1          OUST
                                                                                                  Trees                                         

  B000601-009   N/R             23-May-85   Undetermined   Possible    LA      Acadia      1985   Less Than 50             Spray     1          Oust
                                                                                                  Acres                                         

  I015265-001   Seedling        01-Mar-04   Registered use Possible    TX      Cass        2004   Unknown       Unknown    Unknown   1          Oustar

  I016680-001   Right-of-way    06-Apr-05   Undetermined   Possible    OR      Douglas     2005   13 Acres                 Spray     1          

  I009556-005   Agricultural                Misuse         Possible    NC                  0      Unknown       N/R        N/R       1          OUST
                area                        (accidental)                                                                                        

  B000601-001   N/R             04-May-88   Undetermined   Possible    CA      Kern        1988                 NR         NR        1          Oust

  I016312-001   Forest          01-Apr-05   Undetermined   Possible    OR      Benton      2005   300 Acres     2 Lb/Acre  Spray     1          Westar

  B000601-008   Right-of-way,   23-May-85   Registered use Possible    LA      Acadia      1985   Nr                       Spray     1          Oust
                road                                                                                                                            

  B000601-007   Right-of-way,   23-May-85   Registered use Possible    NE      Scotts      1985   Nr            2 Oz/Acre            1          Oust
                road                                                           Bluff                                                            
  ---------------------------------------------------------------------------------------------------------------------------------------------------------

Source: USEPA, OPP Ecological Incident Information System, October,
2007.

Affected Species: 1 = terrestrial plants, 2 = aquatic plants, 3 =
terrestrial animals, 4= aquatic animals

# APPENDIX F: T-REX Output

**Table F-1. T-REX Model Inputs Used for Sulfometuron Methyl**

+-------------------------------------+------------+---+----+-----------+
| **TREX MODEL INPUTS**               |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
+-------------------------------------+------------+---+----+-----------+
| **Chemical Name:**                  | **Su       |   |    |           |
|                                     | lfometuron |   |    |           |
|                                     | methyl**   |   |    |           |
+-------------------------------------+------------+---+----+-----------+
| **Use:**                            | *          |   |    |           |
|                                     | *non-crop; |   |    |           |
|                                     | forest,    |   |    |           |
|                                     | right      |   |    |           |
|                                     | s-of-way** |   |    |           |
+-------------------------------------+------------+---+----+-----------+
| **Product name and form:**          | **Oust (et |   |    |           |
|                                     | al): water |   |    |           |
|                                     | d          |   |    |           |
|                                     | ispersible |   |    |           |
|                                     | graunule** |   |    |           |
+-------------------------------------+------------+---+----+-----------+
| **% A.I. (leading zero must be      | *          |   |    |           |
| entered for formulations \<1%       | *100.00%** |   |    |           |
| a.i.):**                            |            |   |    |           |
+-------------------------------------+------------+---+----+-----------+
| **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     | 4 |    | 2         |
|                                     | (m         | 6 |    | (mallard) |
|                                     | g/kg-bw)** | 5 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | . |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **LC50     | * |    | 2         |
|                                     | (mg/       | * |    | (mallard) |
|                                     | kg-diet)** | 4 |    |           |
|                                     |            | 6 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | . |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **NOAEL    | * |    | 2         |
|                                     | (m         | * |    |           |
|                                     | g/kg-bw)** |   |    |           |
|                                     |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **NOAEC    | * |    | 1         |
|                                     | (mg/       | * |    |           |
|                                     | kg-diet)** |   |    |           |
|                                     |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **Enter    |   |    | **1.15**  |
|                                     | the Mineau |   |    |           |
|                                     | et al.     |   |    |           |
|                                     | Scaling    |   |    |           |
|                                     | Factor**   |   |    |           |
+-------------------------------------+------------+---+----+-----------+
|  **Mammals**                        |            |   |    |           |
|                                     |            |   |    |           |
|                                     |            |   |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **LD50     | * |    |  Rat      |
|                                     | (m         | * |    |           |
|                                     | g/kg-bw)** | 5 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | . |    |           |
|                                     |            | 0 |    |           |
|                                     |            | 0 |    |           |
|                                     |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     | **LC50     | * |    |           |
|                                     | (mg/       | * |    |           |
|                                     | kg-diet)** |   |    |           |
|                                     |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     |            | 5 |    |   ------  |
|                                     |            | 4 |    | --------- |
| **Reported Chronic Endpoint         |            | 9 |    |   Scaled  |
| (mg/kg-bw/d)**                      |            | . |    |  to 350 g |
|                                     |            | 0 |    |   fr      |
|                                     |            | 0 |    | om Rabbit |
|                                     |            |   |    |   Deve    |
|                                     |            |   |    | lopmental |
|                                     |            |   |    |           |
|                                     |            |   |    | Tox Study |
|                                     |            |   |    |           |
|                                     |            |   |    |   ------  |
|                                     |            |   |    | --------- |
+-------------------------------------+------------+---+----+-----------+
|                                     |            | * |    | ** **     |
|                                     |            | * |    |           |
| **Is dietary concentration          |            | n |    |           |
| (mg/kg-diet) reported from the      |            | o |    |           |
| available chronic mammal study?     |            | * |    |           |
| (yes or no)**                       |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     |            | * |    | ** **     |
|                                     |            | * |    |           |
| **Enter dietary concentration       |            |   |    |           |
| (mg/kg-diet)**                      |            | * |    |           |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+
|                                     |            | * |    | **m       |
|                                     |            | * |    | g/kg-diet |
| **Estimated Chronic Diet            |            | 1 |    | based on  |
| Concentration Equivalent to         |            | 0 |    | standard  |
| Reported Chronic Daily Dose**       |            | 9 |    | FDA lab   |
|                                     |            | 8 |    | rat       |
|                                     |            | 0 |    | con       |
|                                     |            | * |    | version** |
|                                     |            | * |    |           |
+-------------------------------------+------------+---+----+-----------+

<table>
<colgroup>
<col style="width: 12%" />
<col style="width: 12%" />
<col style="width: 9%" />
<col style="width: 8%" />
<col style="width: 10%" />
<col style="width: 8%" />
<col style="width: 10%" />
<col style="width: 8%" />
<col style="width: 10%" />
<col style="width: 8%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="10"><strong>Table F-2. T-REX Output: Upper Bound Kenaga,
Acute Avian Dose-Based Risk Quotients</strong></td>
</tr>
<tr class="even">
<td rowspan="3"><p><strong>Size Class</strong></p>
<p><strong>(grams)</strong></p></td>
<td rowspan="3"><p><strong>Adjusted</strong></p>
<p><strong>LD50</strong></p></td>
<td colspan="8"><strong>EECs and RQs</strong></td>
</tr>
<tr class="odd">
<td colspan="2"><strong>Short Grass</strong></td>
<td><strong>Tall Grass</strong></td>
<td></td>
<td colspan="2"><p><strong>Broadleaf Plants/</strong></p>
<p><strong>Small Insects</strong></p></td>
<td colspan="2"><p><strong>Fruits/Pods/</strong></p>
<p><strong>Seeds/</strong></p>
<p><strong>Large Insects</strong></p></td>
</tr>
<tr class="even">
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
</tr>
<tr class="odd">
<td>20</td>
<td>2414.40</td>
<td>102.50</td>
<td>0.04</td>
<td>46.98</td>
<td>0.02</td>
<td>57.66</td>
<td>0.02</td>
<td>6.41</td>
<td>0.00</td>
</tr>
<tr class="even">
<td>100</td>
<td>3073.65</td>
<td>58.45</td>
<td>0.02</td>
<td>26.79</td>
<td>0.01</td>
<td>32.88</td>
<td>0.01</td>
<td>3.65</td>
<td>0.00</td>
</tr>
<tr class="odd">
<td>1000</td>
<td>4341.65</td>
<td>26.17</td>
<td>0.01</td>
<td>11.99</td>
<td>0.00</td>
<td>14.72</td>
<td>0.00</td>
<td>1.64</td>
<td>0.00</td>
</tr>
</tbody>
</table>

+--------+-------+------+-----+------+-----+-------+-----+--------+
| *      |       |      |     |      |     |       |     |        |
| *Table |       |      |     |      |     |       |     |        |
| F-3.   |       |      |     |      |     |       |     |        |
| T-REX  |       |      |     |      |     |       |     |        |
| O      |       |      |     |      |     |       |     |        |
| utput: |       |      |     |      |     |       |     |        |
| Upper  |       |      |     |      |     |       |     |        |
| Bound  |       |      |     |      |     |       |     |        |
| K      |       |      |     |      |     |       |     |        |
| enaga, |       |      |     |      |     |       |     |        |
| Su     |       |      |     |      |     |       |     |        |
| bacute |       |      |     |      |     |       |     |        |
| Avian  |       |      |     |      |     |       |     |        |
| D      |       |      |     |      |     |       |     |        |
| ietary |       |      |     |      |     |       |     |        |
| Based  |       |      |     |      |     |       |     |        |
| Risk   |       |      |     |      |     |       |     |        |
| Quoti  |       |      |     |      |     |       |     |        |
| ents** |       |      |     |      |     |       |     |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+
| **     | *     |      |     |      |     |       |     |        |
| LC50** | *EECs |      |     |      |     |       |     |        |
|        | and   |      |     |      |     |       |     |        |
|        | RQs** |      |     |      |     |       |     |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+
|        | **    |      | **T |      | **  |       | *   |        |
|        | Short |      | all |      | Bro |       | *Fr |        |
|        | Gr    |      | G   |      | adl |       | uit |        |
|        | ass** |      | ras |      | eaf |       | s/P |        |
|        |       |      | s** |      | Pla |       | ods |        |
|        |       |      |     |      | nts |       | /** |        |
|        |       |      |     |      | /** |       |     |        |
|        |       |      |     |      |     |       | *   |        |
|        |       |      |     |      | *   |       | *Se |        |
|        |       |      |     |      | *Sm |       | eds |        |
|        |       |      |     |      | all |       | /** |        |
|        |       |      |     |      | Ins |       |     |        |
|        |       |      |     |      | ect |       | *   |        |
|        |       |      |     |      | s** |       | *La |        |
|        |       |      |     |      |     |       | rge |        |
|        |       |      |     |      |     |       | Ins |        |
|        |       |      |     |      |     |       | ect |        |
|        |       |      |     |      |     |       | s** |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+
|        | **    | **   | *   | **   | *   | *     | *   | **RQ** |
|        | EEC** | RQ** | *EE | RQ** | *EE | *RQ** | *EE |        |
|        |       |      | C** |      | C** |       | C** |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+
| 4600   | 90.00 | 0.02 | 41  | 0.01 | 50  | 0.01  | 5   | 0.00   |
|        |       |      | .25 |      | .63 |       | .63 |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+
| Size   |       |      |     |      |     |       |     |        |
| class  |       |      |     |      |     |       |     |        |
| not    |       |      |     |      |     |       |     |        |
| used   |       |      |     |      |     |       |     |        |
| for    |       |      |     |      |     |       |     |        |
| d      |       |      |     |      |     |       |     |        |
| ietary |       |      |     |      |     |       |     |        |
| risk   |       |      |     |      |     |       |     |        |
| quo    |       |      |     |      |     |       |     |        |
| tients |       |      |     |      |     |       |     |        |
+--------+-------+------+-----+------+-----+-------+-----+--------+

<table style="width:100%;">
<colgroup>
<col style="width: 10%" />
<col style="width: 9%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="12"><strong>Table F-4. T-REX Output: Upper Bound Kenaga,
Acute Mammalian Dose-Based Risk Quotients</strong></td>
</tr>
<tr class="even">
<td rowspan="3"><p><strong>Size Class</strong></p>
<p><strong>(grams)</strong></p></td>
<td rowspan="3"><p><strong>Adjusted</strong></p>
<p><strong>LD50</strong></p></td>
<td colspan="10"><strong>EECs and RQs</strong></td>
</tr>
<tr class="odd">
<td colspan="2"><strong>Short Grass</strong></td>
<td colspan="2"><strong>Tall Grass</strong></td>
<td colspan="2"><p><strong>Broadleaf Plants/</strong></p>
<p><strong>Small Insects</strong></p></td>
<td colspan="2"><p><strong>Fruits/Pods/</strong></p>
<p><strong>Seeds/</strong></p>
<p><strong>Large Insects</strong></p></td>
<td colspan="2"><strong>Granivore</strong></td>
</tr>
<tr class="even">
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
</tr>
<tr class="odd">
<td>15</td>
<td>10989.15</td>
<td>85.81</td>
<td>0.01</td>
<td>39.33</td>
<td>0.00</td>
<td>48.27</td>
<td>0.00</td>
<td>5.36</td>
<td>0.00</td>
<td>1.19</td>
<td>0.00</td>
</tr>
<tr class="even">
<td>35</td>
<td>8891.40</td>
<td>59.30</td>
<td>0.01</td>
<td>27.18</td>
<td>0.00</td>
<td>33.36</td>
<td>0.00</td>
<td>3.71</td>
<td>0.00</td>
<td>0.82</td>
<td>0.00</td>
</tr>
<tr class="odd">
<td>1000</td>
<td>3845.80</td>
<td>13.75</td>
<td>0.00</td>
<td>6.30</td>
<td>0.00</td>
<td>7.73</td>
<td>0.00</td>
<td>0.86</td>
<td>0.00</td>
<td>0.19</td>
<td>0.00</td>
</tr>
</tbody>
</table>

+--------+-------+------+-----+-------+-----+-------+-----+-------+
| *      |       |      |     |       |     |       |     |       |
| *Table |       |      |     |       |     |       |     |       |
| F-5.   |       |      |     |       |     |       |     |       |
| T-REX  |       |      |     |       |     |       |     |       |
| O      |       |      |     |       |     |       |     |       |
| utput: |       |      |     |       |     |       |     |       |
| Upper  |       |      |     |       |     |       |     |       |
| Bound  |       |      |     |       |     |       |     |       |
| K      |       |      |     |       |     |       |     |       |
| enaga, |       |      |     |       |     |       |     |       |
| C      |       |      |     |       |     |       |     |       |
| hronic |       |      |     |       |     |       |     |       |
| Mam    |       |      |     |       |     |       |     |       |
| malian |       |      |     |       |     |       |     |       |
| D      |       |      |     |       |     |       |     |       |
| ietary |       |      |     |       |     |       |     |       |
| Based  |       |      |     |       |     |       |     |       |
| Risk   |       |      |     |       |     |       |     |       |
| Quoti  |       |      |     |       |     |       |     |       |
| ents** |       |      |     |       |     |       |     |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+
| *      | *     |      |     |       |     |       |     |       |
| *NOAEC | *EECs |      |     |       |     |       |     |       |
| (      | and   |      |     |       |     |       |     |       |
| ppm)** | RQs** |      |     |       |     |       |     |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+
|        | **    |      | **T |       | **  |       | *   |       |
|        | Short |      | all |       | Bro |       | *Fr |       |
|        | Gr    |      | G   |       | adl |       | uit |       |
|        | ass** |      | ras |       | eaf |       | s/P |       |
|        |       |      | s** |       | Pla |       | ods |       |
|        |       |      |     |       | nts |       | /** |       |
|        |       |      |     |       | /** |       |     |       |
|        |       |      |     |       |     |       | *   |       |
|        |       |      |     |       | *   |       | *Se |       |
|        |       |      |     |       | *Sm |       | eds |       |
|        |       |      |     |       | all |       | /** |       |
|        |       |      |     |       | Ins |       |     |       |
|        |       |      |     |       | ect |       | *   |       |
|        |       |      |     |       | s** |       | *La |       |
|        |       |      |     |       |     |       | rge |       |
|        |       |      |     |       |     |       | Ins |       |
|        |       |      |     |       |     |       | ect |       |
|        |       |      |     |       |     |       | s** |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+
|        | **    | **   | *   | *     | *   | *     | *   | *     |
|        | EEC** | RQ** | *EE | *RQ** | *EE | *RQ** | *EE | *RQ** |
|        |       |      | C** |       | C** |       | C** |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+
| 10980  | 90.00 | 0.01 | 41  | 0.00  | 50  | 0.00  | 5   | 0.00  |
|        |       |      | .25 |       | .63 |       | .63 |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+
| Size   |       |      |     |       |     |       |     |       |
| class  |       |      |     |       |     |       |     |       |
| not    |       |      |     |       |     |       |     |       |
| used   |       |      |     |       |     |       |     |       |
| for    |       |      |     |       |     |       |     |       |
| d      |       |      |     |       |     |       |     |       |
| ietary |       |      |     |       |     |       |     |       |
| risk   |       |      |     |       |     |       |     |       |
| quo    |       |      |     |       |     |       |     |       |
| tients |       |      |     |       |     |       |     |       |
+--------+-------+------+-----+-------+-----+-------+-----+-------+

<table style="width:100%;">
<colgroup>
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="12"><strong>Table F-6: T-REX Output: Upper Bound Kenaga,
Chronic Mammalian Dose-Based Risk Quotients</strong></td>
</tr>
<tr class="even">
<td rowspan="3"><p><strong>Size Class</strong></p>
<p><strong>(grams)</strong></p></td>
<td rowspan="3"><strong>Adjusted NOAEL</strong></td>
<td colspan="10"><strong>EECs and RQs</strong></td>
</tr>
<tr class="odd">
<td colspan="2"><strong>Short Grass</strong></td>
<td colspan="2"><strong>Tall Grass</strong></td>
<td colspan="2"><p><strong>Broadleaf Plants/</strong></p>
<p><strong>Small Insects</strong></p></td>
<td colspan="2"><p><strong>Fruits/Pods/</strong></p>
<p><strong>Seeds/</strong></p>
<p><strong>Large Insects</strong></p></td>
<td colspan="2"><strong>Granivore</strong></td>
</tr>
<tr class="even">
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
<td><strong>EEC</strong></td>
<td><strong>RQ</strong></td>
</tr>
<tr class="odd">
<td>15</td>
<td>1206.61</td>
<td>85.81</td>
<td>0.07</td>
<td>39.33</td>
<td>0.03</td>
<td>48.27</td>
<td>0.04</td>
<td>5.36</td>
<td>0.00</td>
<td>1.19</td>
<td>0.00</td>
</tr>
<tr class="even">
<td>35</td>
<td>976.28</td>
<td>59.30</td>
<td>0.06</td>
<td>27.18</td>
<td>0.03</td>
<td>33.36</td>
<td>0.03</td>
<td>3.71</td>
<td>0.00</td>
<td>0.82</td>
<td>0.00</td>
</tr>
<tr class="odd">
<td>1000</td>
<td>422.27</td>
<td>13.75</td>
<td>0.03</td>
<td>6.30</td>
<td>0.01</td>
<td>7.73</td>
<td>0.02</td>
<td>0.86</td>
<td>0.00</td>
<td>0.19</td>
<td>0.00</td>
</tr>
</tbody>
</table>

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

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, the 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 containing 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)]{.underline} =
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]{.underline} = **3.9**

1.8 x 10^-5^ lbs ai/A

**Endangered Plant RQ:**

From 1 acre-inch of surface water: EEC/EC~05~ for vegetative vigor =

[7.03 x 10^-5^ lbs ai/A]{.underline} = **71**

9.9 x 10^-7^ lbs ai/A

**GROUND WATER IRRIGATION**

To calculate risk quotients for plants when ground water contaminated by
sulfometuron methyl is applied as irrigation water 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-inch 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)]{.underline} =
7.48 x 10^-5^ lbs ai/A. 1,000,000,000

Therefore, the **risk quotient for sensitive plants 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]{.underline} = 0.04

1.8 x 10^-5^ lbs ai/A

**Endangered Plant RQ:**

From 1 acre-inch of ground water: EEC/EC~25~ for veg.vigor = [7.48 x
10^-5^ lb ai/A]{.underline} = 0.76

9.9 x 10^-7^ lbs ai/A

# APPENDIX H: Ecological Effects Data Summaries

**I. OPP Guideline Toxicity Studies**

**Freshwater Fish, Acute**

**Bluegill Sunfish, *(Lepomis macrochirus)*.** For bluegill, results
from the range finding test indicated no mortality when 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 buffered 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 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 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.

**Rainbow Trout, *(Oncorhynchus mykiss)*.** Similarly for rainbow trout,
no mortality was observed in a range 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 (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 (measured
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**

**Water 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 range 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 recommended (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
therefore considered a necessary byproduct of increasing the solubility
of the test chemical.

This test was originally classified as supplemental in 1995 by EFED
because of concerns over chemical composition of the dilution water
(filtered fish tank water 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 significantly
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 its 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 confirmed 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**

**Sheepshead minnow (*Cyprinodon 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)
ranging 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 termination (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 classified 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 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
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 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 concentration of 0.031 ppm in water),
the bioavailable (dissolved) portion sulfometuron methyl would have to
be approximately [1500-fold lower]{.underline} 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.

####  {#section-1 .unnumbered}

**Estuarine and Marine Invertebrates, Acute**

**Mysid 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 sublethal 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 sulfometuron 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 % nominal 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 sulfometuron 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 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
classification 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 EECs (i.e., a
maximum peak concentration of 0.031 ppm in water)**,** the bioavailable
(dissolved) portion sulfometuron methyl would have to be approximately
[1300-fold lower]{.underline} 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 control 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 to 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 test 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 registrant's explanation 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 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 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 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
[1000-fold lower]{.underline} 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 the risk assessment conclusions.

####  {#section-2 .unnumbered}

**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; Accession 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 were 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 concentration
(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 the 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 % hatching) 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]{.underline} 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 low
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 solubility of sulfometuron 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
EECs (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 affect 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 from 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.). 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.

Results indicate that mean measured concentrations 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
reproduction 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]{.underline} 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
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
requirements for a chronic study using a freshwater invertebrate.

**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 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 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 problematic. Therefore, 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.
pelliculosa*) 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
termination. 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 requirements 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 was 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*.** The 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 1.045 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 NOAEC 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
sulfometuron 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 counts and
biomass. The results are as follows:

14-d Recovery 14-d Recovery:

[14-d Exposure Conc. Frond Count Inhibition Biomass
Inhibition]{.underline}

1.045 ppb 41.1% 38.3%

0.590 ppb 11.8% 10.8%

0.323 ppb 0.6% - 1.0%

The study authors concluded that sulfometuron methyl was phytotoxic to
duckweed at concentrations of [\>]{.underline} 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, Oral Acute**

**Mallard duck, *Anas platyrhynchos.*** An acute oral toxicity study
with the mallard indicates sulfometuron methyl ([\>]{.underline} 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 (recalculated 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 Acute**

**Mallard duck, *Anas platyrhynchos* and bobwhite quail, *Colinus
virginianus.*** Two, 8-d dietary acute toxicity studies were submitted
on the effects of sulfometuron methyl 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. Mallards 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 abnormal 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, Acute**

**Rat, Sprague Dawley.** The acute toxicity of sulfometuron methyl
(technical grade active ingredient) is indicated by an acute, oral
toxicity study with the rat (MRID 43089201). 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,
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 (toxicity 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
products 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 available 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 loss or gross legions were observed in this study.
This study satisfied guideline requirements for acute oral toxicity with
rats and is considered acceptable.

####  {#section-3 .unnumbered}

**Mammals, Chronic/Developmental**

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 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. 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 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 rabbits because dose levels were not considered high enough
to adequately assess developmental toxicity.

**Terrestrial Invertebrate**

**Honeybee, *Apis mellifera.*** A honeybee acute contact study is
required for sulfometuron methyl because its post-emergence treatment
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 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). 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 Plants**

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 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. Depending 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 sensitive 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]{.underline} 'outliers' 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 value.

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^, respectively. 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]{.underline} 'outliers' 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 Supplemental Studies from ECOTOX**

**Aquatic Organisms**

**Naqvi and Hawkins (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 ranging
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:

+------------+--------+------------------+------------+---------------+
| *          | **Test | **48-h LC50      | **Classi   | **Reference** |
| *Species** | Chem   | (mg/L)**         | fication** |               |
|            | ical** |                  |            |               |
|            |        | **(95%           |            |               |
|            |        | confidence       |            |               |
|            |        | limits)**        |            |               |
+------------+--------+------------------+------------+---------------+
| *Diaptomus | O      | 1315 (1207-1524) | su         | Naqvi and     |
| sp.*       | ust^®^ |                  | pplemental | Hawkins       |
|            |        |                  |            | (1989)        |
|            | (\~93% |                  |            |               |
|            | ai)    |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Eucyclops |        | 1320 (1154-1536) |            |               |
| sp.*       |        |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Alonella  |        | 802 (475-928)    |            |               |
| sp.*       |        |                  |            |               |
+------------+--------+------------------+------------+---------------+
| *Cypria    |        | 2241 (1744-4517) |            |               |
| sp*        |        |                  |            |               |
+------------+--------+------------------+------------+---------------+

This study is classified as supplemental primarily because test
concentrations were not measured in the study and the field collected
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 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 adjusted 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 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 sulfometuron methyl 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]{.underline} 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 considered 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 laboratory
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
sulfometuron methyl (as the formulated product, Oust^®^, % ai not
reported) . Three replicates were used per treatment 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. Reduction 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
classified 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 sulfometuron 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
evaluate 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. Sulfometuron 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 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 (24.9 mg/L). Solvent controls were not significantly
different from 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 study indicate a significant reduction in tail
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 because 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, randomization 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 various treatments was not reported (solvent concentrations were
only reported for the stock solutions).

+-----+--------+-------+------------------+--------+----------+------+
| To  |        |       |                  |        |          |      |
| xic |        |       |                  |        |          |      |
| ity |        |       |                  |        |          |      |
| of  |        |       |                  |        |          |      |
| sul |        |       |                  |        |          |      |
| fom |        |       |                  |        |          |      |
| etu |        |       |                  |        |          |      |
| ron |        |       |                  |        |          |      |
| met |        |       |                  |        |          |      |
| hyl |        |       |                  |        |          |      |
| to  |        |       |                  |        |          |      |
| the |        |       |                  |        |          |      |
| A   |        |       |                  |        |          |      |
| fri |        |       |                  |        |          |      |
| can |        |       |                  |        |          |      |
| cla |        |       |                  |        |          |      |
| wed |        |       |                  |        |          |      |
| f   |        |       |                  |        |          |      |
| rog |        |       |                  |        |          |      |
| f   |        |       |                  |        |          |      |
| rom |        |       |                  |        |          |      |
| a   |        |       |                  |        |          |      |
| st  |        |       |                  |        |          |      |
| udy |        |       |                  |        |          |      |
| by  |        |       |                  |        |          |      |
| F   |        |       |                  |        |          |      |
| ort |        |       |                  |        |          |      |
| et  |        |       |                  |        |          |      |
| al. |        |       |                  |        |          |      |
| (   |        |       |                  |        |          |      |
| 199 |        |       |                  |        |          |      |
| 9). |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
| **  | **Test | **Exp | **Endpoint       | **     | **Study  | **Re |
| Spe | Chem   | osure | (Effect)**       | Effect | Classifi | f.** |
| cie | ical** | Durat |                  | L      | cation** |      |
| s** |        | ion** |                  | evel** |          |      |
|     |        |       |                  |        |          |      |
|     |        |       |                  | **(mg  |          |      |
|     |        |       |                  | a      |          |      |
|     |        |       |                  | i/L)** |          |      |
+-----+--------+-------+------------------+--------+----------+------+
| *X  | sulfom | 96-h  | LC50 (%          | \>     | Supp     | Fort |
| eno | eturon |       | mortality)       | 24.9   | lemental | et   |
| pus | methyl |       |                  |        |          | al.  |
| l   | (99.5% |       | NOAEC (%         | 24.9   |          | (1   |
| aev | ai)    |       | malformations)   | ^(a)^  |          | 999) |
| is* |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
|     |        | 14-d  | NOAEC (tail      | 0.995  |          |      |
|     |        |       | resorption)      |        |          |      |
|     |        |       |                  | 9.95   |          |      |
|     |        |       | LOAEC (tail      |        |          |      |
|     |        |       | resporption)     |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+
|     |        | 30-d  | NOAEC (limb      | 24.    |          |      |
|     |        |       | deformation)     | 9^(a)^ |          |      |
+-----+--------+-------+------------------+--------+----------+------+
| ^(  |        |       |                  |        |          |      |
| a)^ |        |       |                  |        |          |      |
| H   |        |       |                  |        |          |      |
| igh |        |       |                  |        |          |      |
| est |        |       |                  |        |          |      |
| tes |        |       |                  |        |          |      |
| ted |        |       |                  |        |          |      |
| do  |        |       |                  |        |          |      |
| se, |        |       |                  |        |          |      |
| LO  |        |       |                  |        |          |      |
| AEL |        |       |                  |        |          |      |
| not |        |       |                  |        |          |      |
| ac  |        |       |                  |        |          |      |
| hie |        |       |                  |        |          |      |
| ved |        |       |                  |        |          |      |
| in  |        |       |                  |        |          |      |
| stu |        |       |                  |        |          |      |
| dy. |        |       |                  |        |          |      |
+-----+--------+-------+------------------+--------+----------+------+

**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 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 to 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 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 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 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 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 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 (*Pinus 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
fertilization levels. Although this study was designed primarily to
investigate the efficacy 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).

# APPENDIX I; Ecological Effects Data Requirements

+-------+------------+------------+------+---------+--------+-------+
| **    |            |            |      |         |        |       |
| Ecolo |            |            |      |         |        |       |
| gical |            |            |      |         |        |       |
| Ef    |            |            |      |         |        |       |
| fects |            |            |      |         |        |       |
| Data  |            |            |      |         |        |       |
| Re    |            |            |      |         |        |       |
| quire |            |            |      |         |        |       |
| ments |            |            |      |         |        |       |
| for   |            |            |      |         |        |       |
| Su    |            |            |      |         |        |       |
| lfome |            |            |      |         |        |       |
| turon |            |            |      |         |        |       |
| Met   |            |            |      |         |        |       |
| hyl** |            |            |      |         |        |       |
+=======+============+============+======+=========+========+=======+
| **G   | **Data     | **Test     | **MR | **Study | **Data | *     |
| uidel | Req        | Material** | ID** | Cl      | Requi  | *More |
| ine** | uirement** |            |      | assific | rement | Data  |
|       |            |            |      | ation** | Met?** | Need  |
|       |            |            |      |         |        | ed?** |
+-------+------------+------------+------+---------+--------+-------+
| 71-1  | Avian Oral | su         | 24   | Acc     | Yes    | No    |
|       | LD~50~     | lfometuron | 5375 | eptable |        |       |
|       |            | methyl     |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 71-2  | Avian      | su         | 7    | Acc     | Yes    | No    |
|       | Dietary    | lfometuron | 1414 | eptable |        |       |
|       | LC~50~     | methyl     |      | Acc     |        |       |
|       |            |            | 24   | eptable |        |       |
|       |            |            | 6409 |         |        |       |
|       |            |            | ^    |         |        |       |
|       |            |            | (2)^ |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 71-4  | Avian      | su         |      | Data    | No     | Res   |
|       | Re         | lfometuron |      | Gap     |        | erved |
|       | production | methyl     |      |         |        | ^(3)^ |
+-------+------------+------------+------+---------+--------+-------+
| 72-1  | Freshwater | su         | 4    | Acc     | Yes    | No    |
|       | Fish       | lfometuron | 3501 | eptable |        |       |
|       | LC~50~     | methyl     | 8-01 |         |        |       |
|       |            |            |      |         |        |       |
|       |            |            | 4    |         |        |       |
|       |            |            | 3501 |         |        |       |
|       |            |            | 8-02 |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72-2  | Freshwater | su         | 4    | Acc     | Yes    | No    |
|       | In         | lfometuron | 3501 | eptable |        |       |
|       | vertebrate | methyl     | 8-03 | ^(1)^   |        |       |
|       | Acute      |            |      |         |        |       |
|       | LC~50~     |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72    | Estuar     | su         | 4    | Suppl   | No     | Res   |
| -3(a) | ine/Marine | lfometuron | 1672 | emental |        | erved |
|       | Fish       | methyl     | 8-03 | ^(1)^   |        | ^(3)^ |
|       | LC~50~     |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72    | Estuar     | su         | 4    | Suppl   | No     | Res   |
| -3(b) | ine/Marine | lfometuron | 1672 | emental |        | erved |
|       | Mollusk    | methyl     | 8-05 | ^(1)^   |        | ^(3)^ |
|       | EC~50~     |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72    | Estuar     | su         | 4    | Suppl   | No     | Res   |
| -3(c) | ine/Marine | lfometuron | 1672 | emental |        | erved |
|       | Shrimp     | methyl     | 8-04 | ^(1)^   |        | ^(3)^ |
|       | EC~50~     |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72    | Freshwater | su         | 42   | Invalid | No     | Res   |
| -4(a) | Fish Early | lfometuron | 3857 | ^(1)^   |        | erved |
|       | Life-Stage | methyl     | -04; |         |        | ^(3)^ |
|       |            |            | 24   |         |        |       |
|       |            |            | 9796 |         |        |       |
|       |            |            | ^    |         |        |       |
|       |            |            | (2)^ |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 72    | Aquatic    | su         | 4    | Acc     | Yes    | No    |
| -4(b) | In         | lfometuron | 1672 | eptable |        |       |
|       | vertebrate | methyl     | 8-06 |         |        |       |
|       | Life-Cycle |            |      |         |        |       |
|       | (f         |            |      |         |        |       |
|       | reshwater) |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 123   | Seedling   | su         | 4    | Acc     | Yes    | No    |
| -1(a) | Emergence  | lfometuron | 3538 | eptable |        |       |
|       |            | methyl     | 5-01 |         |        |       |
|       | (Tier II)  |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 123   | Vegetative | su         | 4    | Acc     | Yes    | No    |
| -1(b) | Vigor      | lfometuron | 3538 | eptable |        |       |
|       | (Tier II)  | methyl     | 5-01 |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 123-2 | Blue-green | su         | 4    | Acc     | Yes    | No    |
|       | Algae      | lfometuron | 3538 | eptable |        |       |
| Aq    | (Tier II)  | methyl     | 5-02 |         |        |       |
| uatic |            |            |      |         |        |       |
| Plant |            |            |      |         |        |       |
| G     |            |            |      |         |        |       |
| rowth |            |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
|       | Duckweed,  | su         | 4    | Acc     | Yes    | No    |
|       | Lemna      | lfometuron | 3538 | eptable |        |       |
|       | gibba      | methyl     | 5-03 |         |        |       |
|       |            |            |      |         |        |       |
|       | (Tier II)  |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
|       | Freshwater | su         | 4    | Acc     | Yes    | No    |
|       | Diatom,    | lfometuron | 3538 | eptable |        |       |
|       | Navicula   | methyl     | 5-02 |         |        |       |
|       | (Tier 1)   |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
|       | Marine     | su         | 4    | Acc     | Yes    | No    |
|       | Diatom     | lfometuron | 3538 | eptable |        |       |
|       | (Tier 1)   | methyl     | 5-02 |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
|       | Green      | su         | 4    | Acc     | Yes    | No    |
|       | algae      | lfometuron | 1680 | eptable |        |       |
|       | (Tier II)  | methyl     | 1-02 |         |        |       |
+-------+------------+------------+------+---------+--------+-------+
| 141-1 | Honey Bee  | su         | 4    | Acc     | Yes    | No    |
|       | Acute      | lfometuron | 1672 | eptable |        |       |
|       |            | methyl     | 8-10 |         |        |       |
|       | Contact    |            |      |         |        |       |
|       | LD~50~     |            |      |         |        |       |
+-------+------------+------------+------+---------+--------+-------+

^(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 change 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.

# APPENDIX J: Ecological Effects Studies 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 Tree Plantings. *Proc.Northeast.Weed Sci.Soc.* 39: 249-253.
([Rejection Rationale:]{.underline} 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:]{.underline} 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:]{.underline} 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:]{.underline} Endpoint Relevancy, Exposure Route;
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:]{.underline} 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:]{.underline}
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:]{.underline} Target/Efficacy study; EcoReference No.: 90965)
EcoReference No.: 49268)

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
Rationale:]{.underline} 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 Unilaterally
Nephrectomized Rats Given N-Ethyl-N-Hydroxyethylnitrosasmine Orally.
*Carcinogenesis* 2: 1299-1302. ([Rejection Rationale:]{.underline}
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:]{.underline} Endpoint relevancy; EcoReference
No.: 90556)

King, 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:]{.underline} 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:]{.underline} Endpoint relevancy; EcoReference No.: 90513)

Kramers, P. G. N. (1977). Mutagenicity of Saccharin in Drosophila: The
Possible Role of Contaminants. *Mutat.Res.* 56: 163-167. ([Rejection
Rationale:]{.underline} Endpoint relevancy; EcoReference No.: 90961)

Liscia, A., Masala, C., Crnjar, R., Sollai, G., and Solari, P. (2004).
Saccharin Stimulates the \"Deterrent\" Cell in the Blowfly: Behavioral
and Electrophysiological Evidence. *Physiol.Behav.* 80: 637-646.
([Rejection Rationale:]{.underline} 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:]{.underline} Endpoint relevancy; EcoReference No.: 90555)

Pszczolkowski, M. A. and Brown, J. J. (2003). Effect of Sugars and
Non-Nutritive Sugar Substitutes on Consumption of Apple Leaves by
Codling Moth Neonates. *Phytoparasitica* 31: 283-291. ([Rejection
Rationale:]{.underline} Target/Efficacy; EcoReference No.: 91055)

Sivan, A. and Arad, S. (1998). Intraspecific Transfer of Herbicide
Resistance in the Red Microalga Porphyridium sp. (Rhodophyceae) via
Protoplast Fusion. *J.Phycol.* 34: 706-711. ([Rejection
Rationale:]{.underline} Target/Efficacy; EcoReference No.: 61449)

**Initial Screen Acceptable for ECOTOX but not OPP**

Amin, S., Moore, 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\
Chemical of Concern: TCDD,PCB,SAC; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: REP,GRO,BEH; [Rejection Code]{.underline}: 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]{.underline}: T; [Effect
Codes]{.underline}: CEL; [Rejection Code]{.underline}: 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). Assays 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 No.: 90967\
Chemical of Concern: PbAC,EXQ,SAC,CTC; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: MOR,PHY; [Rejection Code]{.underline}: 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. (1994). Fetax
Interlaboratory Validation Study: Phase II Testing.
*Environ.Toxicol.Chem.* 13: 1629-1637.

EcoReference No.: 13502\
Chemical of Concern: SMM; [Habitat]{.underline}: A; [Rejection
Code]{.underline}: NO CONTROL(SMM).

5\. Boswell, K. J., Reid, M. L., Fitch, J. V., Bennett, 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]{.underline}: T; [Effect
Codes]{.underline}: GRO,BEH; [Rejection Code]{.underline}: 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 Toxicity Assessment, 2nd Volume, ASTM STP 1115, Philadelphia,
PA* 101-106.

EcoReference No.: 17181\
Chemical of Concern: SMM,CuS; [Habitat]{.underline}: A; [Effect
Codes]{.underline}: BCM,GRO; [Rejection Code]{.underline}: LITE EVAL
CODED(CuS),NO ENDPOINT(SMM).

7\. Byl, T. D., Sutton, H. D., and Klaine, 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]{.underline}: A; [Effect
Codes]{.underline}: BCM,GRO; [Rejection Code]{.underline}: 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]{.underline}: T; [Effect
Codes]{.underline}: GRO,BCM,CEL; [Rejection Code]{.underline}: NO
CONTROL,NO ENDPOINT(ETU,SAC).

9\. Duan, J. J. and Prokopy, R. J. (1993). Toward Developing
Pesticide-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]{.underline}: T; [Effect
Codes]{.underline}: BEH; [Rejection Code]{.underline}: 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 Model Systems.
*Pestic.Sci.* 55: 580-582 .

EcoReference No.: 90964\
Chemical of Concern: SMM,PCP,PAQT,DU,ACR,BTC,ATZ,BSF,CPP,MBZ;
[Habitat]{.underline}: A; [Effect Codes]{.underline}: POP; [Rejection
Code]{.underline}: NO CONTROL,ENDPOINT(SMM,PCP,ATZ).

11\. Ferguson, S. A., Delclos, K. B., Newbold, R. R., and Flynn, K. M.
(2003). Dietary Ethinyl Estradiol Exposure During Development Causes
Increased Voluntary Sodium Intake and Mild Maternal and Offspring
Toxicity in Rats. *Neurotoxicol.Teratol.* 25: 491-501.

EcoReference No.: 90547\
Chemical of Concern: EED,SAC; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: GRO,BEH; [Rejection Code]{.underline}: 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 Result from Nonylphenol Exposure.
*Neurotoxicol.Teratol.* 22: 583-591.

EcoReference No.: 68835\
Chemical of Concern: SAC,NYP; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: BEH,GRO,MOR,REP; [Rejection Code]{.underline}: 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]{.underline}: T; [Effect
Codes]{.underline}: GRO,BEH; [Rejection Code]{.underline}: 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]{.underline}: T; [Effect
Codes]{.underline}: GRO; [Rejection Code]{.underline}: 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,AMTR,CZE,SMM;
[Habitat]{.underline}: AT; [Effect Codes]{.underline}: PHY; [Rejection
Code]{.underline}: 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. *Plant Physiol.(Bethesda)* 85: 898-901.

EcoReference No.: 90536\
Chemical of Concern: SMM; [Habitat]{.underline}: A; [Effect
Codes]{.underline}: POP,PHY; [Rejection Code]{.underline}: NO
ENDPOINT(SMM).

17\. Harvey, J. H. Jr., Dulka, J. J., and Anderson, J. J. (1985).
Properties of Sulfometuron Methyl 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]{.underline}: A; [Effect
Codes]{.underline}: ACC; [Rejection Code]{.underline}: 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.-Biol.Interact.* 11: 225-233.

EcoReference No.: 91040\
Chemical of Concern: SAC; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: PHY; [Rejection Code]{.underline}: NO ENDPOINT(SAC).

19\. Ikeda, M., Mitsui, T., Setani, K., Tamura, M., Kakeyama, M., Sone,
H., Tohyama, C., and Tomita, T. (2005). 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]{.underline}: T; [Effect
Codes]{.underline}: BEH,REP,GRO,BCM,PHY; [Rejection Code]{.underline}:
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 .

EcoReference No.: 90546\
Chemical of Concern: ETHN,SAC,DDT,AND; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: CEL,BCM; [Rejection Code]{.underline}: NO
ENDPOINT(SAC).

21\. Jaffe, R. L. (1995). Rapid Assay of Cytotoxicity Using Tetramitus
flagellates. *Toxicol.Ind.Health* 11: 543-558.

EcoReference No.: 5895\
Chemical of Concern: Cd,SMM; [Habitat]{.underline}: A; [Rejection
Code]{.underline}: 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\
Chemical of Concern: SMM; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: ACC; [Rejection Code]{.underline}: NO
CONTROL,ENDPOINT(SMM).

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]{.underline}: A; [Effect
Codes]{.underline}: CEL; [Rejection Code]{.underline}: NO CONTROL(SMM).

24\. Kuhns, 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]{.underline}: T; [Effect
Codes]{.underline}: POP,PHY; [Rejection Code]{.underline}: 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]{.underline}: A; [Effect
Codes]{.underline}: BCM; [Rejection Code]{.underline}: NO ENDPOINT(SMM).

26\. Landstein, D., Epelbaum, S., Arad, S., Barak, Z., and Chipman, D.
M. (1995). Metabolic Response of Chlorella emersonii to the Herbicide
Sulfometuron Methyl. *Planta* 197: 219-224.

EcoReference No.: 90966\
Chemical of Concern: SMM; [Habitat]{.underline}: A; [Effect
Codes]{.underline}: BCM,PHY; [Rejection Code]{.underline}: NO
ENDPOINT(TARGET-SMM).

27\. Langeland, K. A. (1986). Management Program for Alligatorweed in
North 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]{.underline}: AT; [Effect Codes]{.underline}: POP; [Rejection
Code]{.underline}: NO CONTROL(SMM,HXZ,IZP,GYP),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.

EcoReference No.: 90535\
Chemical of Concern: SMM; [Habitat]{.underline}: A; [Effect
Codes]{.underline}: POP,PHY; [Rejection Code]{.underline}: 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 (Insecticide), Treflan, Msma, Oust.
*Environ.Pollut.* 48: 275-283.

EcoReference No.: 12802\
Chemical of Concern: SMM,TFN; [Habitat]{.underline}: A; [Effect
Codes]{.underline}: MOR; [Rejection Code]{.underline}: 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]{.underline}: T; [Effect
Codes]{.underline}: GRO,BEH; [Rejection Code]{.underline}: 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]{.underline}: 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.

EcoReference No.: 90538\
Chemical of Concern: SAC,CdCl; [Habitat]{.underline}: T; [Effect
Codes]{.underline}: GRO,BEH; [Rejection Code]{.underline}: 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]{.underline}: A; [Effect Codes]{.underline}: GRO,MOR;
[Rejection Code]{.underline}: NO CONTROL(ALL 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.

EcoReference No.: 74836\
Chemical of Concern: CBF,PYT,MTM,ACP,CPY,DEM,MLN,CBL,FNV,PAQT,GYP,SMM ;
[Habitat]{.underline}: T; [Effect Codes]{.underline}: PHY; [Rejection
Code]{.underline}: NO ENDPOINT(ALL CHEMS).

35\. Van-Moppes, D., Barak, Z., Chipman, D. M., Gollop, N., and Arad, S.
(1989). An Herbicide (Sulfometuron Methyl) Resistant Mutant in
Porphyridium (Rhodophyta). *J.Phycol.* 25: 108-112.

> EcoReference No.: 90533\
> Chemical of Concern: SMM; [Habitat]{.underline}: A; [Effect
> Codes]{.underline}: POP,PHY; [Rejection Code]{.underline}: NO
> ENDPOINT(SMM)

[^1]: That is, 0.375 pounds of active ingredient per acre per year.

[^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
    (calculated 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
    first-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.

[^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.

[^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 AgDRIFT assessment should not be presumed to represent more
    conservative (higher exposure) scenarios than those represented in a
    Tier II AgDRIFT assessment.

[^6]: