Document ID: EPA-HQ-OPP-2008-0129-0007
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-02-27T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION
AGENCY

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

SULFOMETURON METHYL

PC Code: 122001; CAS Number: 74222-97-2

Note: Appendix A has been slightly revised from the 11/28/07 review (DP
Barcode D346171) per registrant comment.

 Prepared by:

M. Barrett,  Chemist, 

Environmental Fate Reviewer, ERB V

K. Sappington, Biologist, 

Ecological Effects Reviewer, ERB V

Approved by:

Mah Shamim, PhD, Chief ERB V	February 14, 2008

DP Barcode D334277

United States Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave.

Mail Code 7507P 

Washington, D.C. 20460

TABLE OF CONTENTS

  TOC \o "1-4" \h \z \u    HYPERLINK \l "_Toc191187505"  1.	EXECUTIVE
SUMMARY	  PAGEREF _Toc191187505 \h  8  

  HYPERLINK \l "_Toc191187506"  1.1.	Nature of Chemical Stressor	 
PAGEREF _Toc191187506 \h  8  

  HYPERLINK \l "_Toc191187507"  1.2.	Conclusions- Exposure
Characterization	  PAGEREF _Toc191187507 \h  8  

  HYPERLINK \l "_Toc191187508"  1.3.	Conclusions- Effects
Characterization	  PAGEREF _Toc191187508 \h  9  

  HYPERLINK \l "_Toc191187509"  1.4.	Potential Risks to Non-target
Animals and Plants	  PAGEREF _Toc191187509 \h  10  

  HYPERLINK \l "_Toc191187510"  1.5.	Conclusions - Endangered Species	 
PAGEREF _Toc191187510 \h  11  

  HYPERLINK \l "_Toc191187511"  1.6.	Identification of Uncertainties and
Their Impact on the Risk Assessment	  PAGEREF _Toc191187511 \h  13  

  HYPERLINK \l "_Toc191187512"  1.6.1.	Environmental Fate and Exposure	 
PAGEREF _Toc191187512 \h  13  

  HYPERLINK \l "_Toc191187513"  1.6.2.	Ecological Effects	  PAGEREF
_Toc191187513 \h  14  

  HYPERLINK \l "_Toc191187514"  2.	PROBLEM FORMULATION	  PAGEREF
_Toc191187514 \h  15  

  HYPERLINK \l "_Toc191187515"  2.1.	Nature of the Regulatory Action	 
PAGEREF _Toc191187515 \h  15  

  HYPERLINK \l "_Toc191187516"  2.2.	Stressor Source and Distribution	 
PAGEREF _Toc191187516 \h  15  

  HYPERLINK \l "_Toc191187517"  2.2.1.	Nature of the Chemical Stressor	 
PAGEREF _Toc191187517 \h  15  

  HYPERLINK \l "_Toc191187518"  2.2.2.	Overview of Pesticide Usage	 
PAGEREF _Toc191187518 \h  17  

  HYPERLINK \l "_Toc191187519"  2.3.	Receptors	  PAGEREF _Toc191187519
\h  17  

  HYPERLINK \l "_Toc191187520"  2.3.1.	Aquatic and Terrestrial Effects	 
PAGEREF _Toc191187520 \h  17  

  HYPERLINK \l "_Toc191187521"  2.3.2.	Ecosystems at Risk	  PAGEREF
_Toc191187521 \h  19  

  HYPERLINK \l "_Toc191187522"  2.4.	Assessment Endpoints	  PAGEREF
_Toc191187522 \h  19  

  HYPERLINK \l "_Toc191187523"  2.5.	Conceptual Model	  PAGEREF
_Toc191187523 \h  20  

  HYPERLINK \l "_Toc191187524"  2.5.1.	Risk Hypotheses	  PAGEREF
_Toc191187524 \h  20  

  HYPERLINK \l "_Toc191187525"  2.5.2.	Conceptual Diagram	  PAGEREF
_Toc191187525 \h  20  

  HYPERLINK \l "_Toc191187526"  2.6.	Analysis Plan	  PAGEREF
_Toc191187526 \h  24  

  HYPERLINK \l "_Toc191187527"  2.6.1.	Conclusions from Previous Risk
Assessments	  PAGEREF _Toc191187527 \h  24  

  HYPERLINK \l "_Toc191187528"  2.6.2.	Preliminary Identification of
Data Gaps and Analysis Plan	  PAGEREF _Toc191187528 \h  25  

  HYPERLINK \l "_Toc191187529"  2.6.3.	Measures of Effect and Exposure	 
PAGEREF _Toc191187529 \h  25  

  HYPERLINK \l "_Toc191187530"  3.	ANALYSIS	  PAGEREF _Toc191187530 \h 
27  

  HYPERLINK \l "_Toc191187531"  3.1.	USE CHARACTERIZATION	  PAGEREF
_Toc191187531 \h  27  

  HYPERLINK \l "_Toc191187532"  3.2.	EXPOSURE CHARACTERIZATION	  PAGEREF
_Toc191187532 \h  33  

  HYPERLINK \l "_Toc191187533"  3.2.1.	Environmental Fate and Transport
Characterization	  PAGEREF _Toc191187533 \h  33  

  HYPERLINK \l "_Toc191187534"  3.2.2.	Measures of Aquatic Exposure	 
PAGEREF _Toc191187534 \h  43  

  HYPERLINK \l "_Toc191187535"  3.2.2.1.	Aquatic Exposure Monitoring and
Field Data	  PAGEREF _Toc191187535 \h  43  

  HYPERLINK \l "_Toc191187536"  3.2.2.2.	Aquatic Exposure Modeling	 
PAGEREF _Toc191187536 \h  43  

  HYPERLINK \l "_Toc191187537"  3.2.3.	Measures of Terrestrial  Exposure
  PAGEREF _Toc191187537 \h  51  

  HYPERLINK \l "_Toc191187538"  3.2.3.1.	Terrestrial Exposure Modeling	 
PAGEREF _Toc191187538 \h  51  

  HYPERLINK \l "_Toc191187539"  3.2.3.2.	Residue Studies	  PAGEREF
_Toc191187539 \h  56  

  HYPERLINK \l "_Toc191187540"  3.2.4.	Uncertainties and Limitations for
this Exposure Assessment	  PAGEREF _Toc191187540 \h  56  

  HYPERLINK \l "_Toc191187541"  3.2.4.1.	Limitations In Knowledge Of
Actual Use Patterns	  PAGEREF _Toc191187541 \h  56  

  HYPERLINK \l "_Toc191187542"  3.2.4.2.	Variability In Sulfometuron
Environmental Persistence	  PAGEREF _Toc191187542 \h  57  

  HYPERLINK \l "_Toc191187543"  3.2.4.3.	Exposure To Sulfometuron Methyl
Degradates	  PAGEREF _Toc191187543 \h  57  

  HYPERLINK \l "_Toc191187544"  3.3.	ECOLOGICAL EFFECTS CHARACTERIZATION
  PAGEREF _Toc191187544 \h  57  

  HYPERLINK \l "_Toc191187545"  3.3.1.	Aquatic Effects Characterization	
 PAGEREF _Toc191187545 \h  59  

  HYPERLINK \l "_Toc191187546"  3.3.1.1.	Freshwater Fish, Acute	 
PAGEREF _Toc191187546 \h  59  

  HYPERLINK \l "_Toc191187547"  3.3.1.2.	Freshwater Invertebrates, Acute
  PAGEREF _Toc191187547 \h  60  

  HYPERLINK \l "_Toc191187548"  3.3.1.3.	Estuarine and marine Fish,
Acute	  PAGEREF _Toc191187548 \h  60  

  HYPERLINK \l "_Toc191187549"  3.3.1.4.	Estuarine and marine
Invertebrates, Acute	  PAGEREF _Toc191187549 \h  61  

  HYPERLINK \l "_Toc191187550"  3.3.1.5.	Freshwater Fish, Chronic	 
PAGEREF _Toc191187550 \h  62  

  HYPERLINK \l "_Toc191187551"  3.3.1.6.	Freshwater Invertebrate,
Chronic	  PAGEREF _Toc191187551 \h  62  

  HYPERLINK \l "_Toc191187552"  3.3.1.7.	Aquatic Animal Sublethal
Effects: Formulated Product  and Degradate Toxicity	  PAGEREF
_Toc191187552 \h  63  

  HYPERLINK \l "_Toc191187553"  3.3.1.8.	Field Studies	  PAGEREF
_Toc191187553 \h  64  

  HYPERLINK \l "_Toc191187554"  3.3.1.9.	Aquatic Plants	  PAGEREF
_Toc191187554 \h  65  

  HYPERLINK \l "_Toc191187555"  3.3.2.	Terrestrial Effects
Characterization	  PAGEREF _Toc191187555 \h  66  

  HYPERLINK \l "_Toc191187556"  3.3.2.1.	Acute Effects on Birds	 
PAGEREF _Toc191187556 \h  66  

  HYPERLINK \l "_Toc191187557"  3.3.2.2.	Acute Effects on Mammals	 
PAGEREF _Toc191187557 \h  67  

  HYPERLINK \l "_Toc191187558"  3.3.2.3.	Acute Effects on
Terrestrial-phase Amphibians, Reptiles and Beneficial Insects	  PAGEREF
_Toc191187558 \h  68  

  HYPERLINK \l "_Toc191187559"  3.3.2.4.	Chronic Effects on Birds	 
PAGEREF _Toc191187559 \h  68  

  HYPERLINK \l "_Toc191187560"  3.3.2.5.	Mammals,  Reproductive Effects	
 PAGEREF _Toc191187560 \h  69  

  HYPERLINK \l "_Toc191187561"  3.3.2.6.	Terrestrial Animal Sublethal
Effects, Formulated Product and Degradation Products	  PAGEREF
_Toc191187561 \h  69  

  HYPERLINK \l "_Toc191187562"  3.3.2.7.	Field Studies	  PAGEREF
_Toc191187562 \h  70  

  HYPERLINK \l "_Toc191187563"  3.3.2.8.	Terrestrial Plants	  PAGEREF
_Toc191187563 \h  70  

  HYPERLINK \l "_Toc191187564"  4.	RISK CHARACTERIZATION	  PAGEREF
_Toc191187564 \h  73  

  HYPERLINK \l "_Toc191187565"  4.1.	Risk Estimation - Integration of
Exposure and Effects Data	  PAGEREF _Toc191187565 \h  73  

  HYPERLINK \l "_Toc191187566"  4.1.1.	Non-target Aquatic Animals and
Plants	  PAGEREF _Toc191187566 \h  75  

  HYPERLINK \l "_Toc191187567"  4.1.1.1.	Fish and Aquatic Invertebrates	
 PAGEREF _Toc191187567 \h  75  

  HYPERLINK \l "_Toc191187568"  4.1.1.2.	Aquatic Plants	  PAGEREF
_Toc191187568 \h  76  

  HYPERLINK \l "_Toc191187569"  4.1.2.	Non-target Terrestrial Animals	 
PAGEREF _Toc191187569 \h  77  

  HYPERLINK \l "_Toc191187570"  4.1.2.1.	Birds, Acute Risks	  PAGEREF
_Toc191187570 \h  77  

  HYPERLINK \l "_Toc191187571"  4.1.2.2.	Birds, Chronic Risks	  PAGEREF
_Toc191187571 \h  78  

  HYPERLINK \l "_Toc191187572"  4.1.2.3.	Mammals, Acute Risks	  PAGEREF
_Toc191187572 \h  78  

  HYPERLINK \l "_Toc191187573"  4.1.2.4.	Mammals, Chronic Risks	 
PAGEREF _Toc191187573 \h  79  

  HYPERLINK \l "_Toc191187574"  4.1.2.5.	Non-Target Terrestrial-phase
Amphibians, Reptiles and Terrestrial Invertebrates	  PAGEREF
_Toc191187574 \h  80  

  HYPERLINK \l "_Toc191187575"  4.1.3.	Non-target Terrestrial Plants	 
PAGEREF _Toc191187575 \h  81  

  HYPERLINK \l "_Toc191187576"  4.1.3.1.	Non-Endangered and Endangered
Plant Risks	  PAGEREF _Toc191187576 \h  81  

  HYPERLINK \l "_Toc191187577"  4.1.4.	Use of Contaminated Irrigation
Waters	  PAGEREF _Toc191187577 \h  82  

  HYPERLINK \l "_Toc191187578"  4.2.	RISK DESCRIPTION	  PAGEREF
_Toc191187578 \h  83  

  HYPERLINK \l "_Toc191187579"  4.2.1.	Risk to Aquatic Animals and
Plants	  PAGEREF _Toc191187579 \h  83  

  HYPERLINK \l "_Toc191187580"  4.2.1.1.	Fish and Aquatic Invertebrates	
 PAGEREF _Toc191187580 \h  83  

  HYPERLINK \l "_Toc191187581"  4.2.1.2.	Non-target Aquatic-phase
Amphibians	  PAGEREF _Toc191187581 \h  85  

  HYPERLINK \l "_Toc191187582"  4.2.1.3.	Aquatic Plants	  PAGEREF
_Toc191187582 \h  86  

  HYPERLINK \l "_Toc191187583"  4.2.1.4.	Aquatic Toxicity of
Sulfometuron Methyl Degradates	  PAGEREF _Toc191187583 \h  87  

  HYPERLINK \l "_Toc191187584"  4.2.2.	Risk to Terrestrial Animals	 
PAGEREF _Toc191187584 \h  90  

  HYPERLINK \l "_Toc191187585"  4.2.2.1.	Birds	  PAGEREF _Toc191187585
\h  90  

  HYPERLINK \l "_Toc191187586"  4.2.2.2.	Mammals	  PAGEREF _Toc191187586
\h  92  

  HYPERLINK \l "_Toc191187587"  4.2.2.3.	Non-target Terrestrial-phase
Amphibians, Reptiles, and Beneficial Insects	  PAGEREF _Toc191187587 \h 
92  

  HYPERLINK \l "_Toc191187588"  4.2.3.	Risk to Terrestrial Plants	 
PAGEREF _Toc191187588 \h  92  

  HYPERLINK \l "_Toc191187589"  4.2.3.1.	Tier 1 Modeling of Runoff and
Spray Drift	  PAGEREF _Toc191187589 \h  92  

  HYPERLINK \l "_Toc191187590"  4.2.3.2.	Field and Greenhouse Studies	 
PAGEREF _Toc191187590 \h  93  

  HYPERLINK \l "_Toc191187591"  4.2.3.3.	Contaminated Irrigation Water	 
PAGEREF _Toc191187591 \h  94  

  HYPERLINK \l "_Toc191187592"  4.2.4.	Refined Spray Drift Analysis	 
PAGEREF _Toc191187592 \h  95  

  HYPERLINK \l "_Toc191187593"  4.2.5.	Review of Incident Data	  PAGEREF
_Toc191187593 \h  97  

  HYPERLINK \l "_Toc191187594"  4.2.6.	Overall Ecological Risk
Conclusions	  PAGEREF _Toc191187594 \h  98  

  HYPERLINK \l "_Toc191187595"  4.2.7.	Endocrine Effects	  PAGEREF
_Toc191187595 \h  99  

  HYPERLINK \l "_Toc191187596"  4.2.8.	Federally Threatened and
Endangered (Listed) Species	  PAGEREF _Toc191187596 \h  99  

  HYPERLINK \l "_Toc191187597"  4.2.8.1.	Action Area	  PAGEREF
_Toc191187597 \h  99  

  HYPERLINK \l "_Toc191187598"  4.2.8.2.	Taxonomic Groups Potentially at
Risk	  PAGEREF _Toc191187598 \h  100  

  HYPERLINK \l "_Toc191187599"  4.3.	Description of Assumptions,
Limitations, Uncertainties, and Data Gaps	  PAGEREF _Toc191187599 \h 
105  

  HYPERLINK \l "_Toc191187600"  4.3.1.	Assumptions and Limitations
Related to Effects on all Species	  PAGEREF _Toc191187600 \h  105  

  HYPERLINK \l "_Toc191187601"  4.3.2.	Assumptions and Limitations
Related to Effects on Aquatic Species	  PAGEREF _Toc191187601 \h  107  

  HYPERLINK \l "_Toc191187602"  4.3.3.	Assumptions and Limitations
Related to Effects on Terrestrial Species	  PAGEREF _Toc191187602 \h 
107  

  HYPERLINK \l "_Toc191187603"  5.	Literature Cited	  PAGEREF
_Toc191187603 \h  108  

  HYPERLINK \l "_Toc191187604"  6.	APPENDICES	  PAGEREF _Toc191187604 \h
 111  

  HYPERLINK \l "_Toc191187605"  APPENDIX A: Structures and Chemical
Names of Sulfometuron methyl Metabolites	  PAGEREF _Toc191187605 \h  111
 

  HYPERLINK \l "_Toc191187606"  APPENDIX B: Environmental Fate Data
Requirements	  PAGEREF _Toc191187606 \h  113  

  HYPERLINK \l "_Toc191187607"  APPENDIX C:  Ecological Aquatic Exposure
Modeling	  PAGEREF _Toc191187607 \h  115  

  HYPERLINK \l "_Toc191187608"  APPENDIX D:  Terrplant Spreadsheet	 
PAGEREF _Toc191187608 \h  123  

  HYPERLINK \l "_Toc191187609"  APPENDIX E: Adverse Ecological Incidents
Associated with Sulfometuron Methyl Use	  PAGEREF _Toc191187609 \h  125 

  HYPERLINK \l "_Toc191187610"  APPENDIX F: T-REX Output	  PAGEREF
_Toc191187610 \h  127  

  HYPERLINK \l "_Toc191187611"  APPENDIX G:  Modeling of Terrestrial
plant Exposure from Contaminated irrigation Water	  PAGEREF
_Toc191187611 \h  129  

  HYPERLINK \l "_Toc191187612"  APPENDIX H: Ecological Effects Data
Summaries	  PAGEREF _Toc191187612 \h  131  

  HYPERLINK \l "_Toc191187613"  APPENDIX I; Ecological Effects Data
Requirements	  PAGEREF _Toc191187613 \h  144  

  HYPERLINK \l "_Toc191187614"  APPENDIX J: Ecological Effects Studies
Rejected by OPP	  PAGEREF _Toc191187614 \h  146  

 

LIST OF TABLES

  TOC \h \z \c "Table"    HYPERLINK \l "_Toc191187615"  Table 1.  Listed
Taxonomic Groups Potentially at Risk from Direct or Indirect Effects of
Sulfometuron Methyl Application for Vegetative Management Throughout the
U.S.	  PAGEREF _Toc191187615 \h  12  

  HYPERLINK \l "_Toc191187616"  Table 2. Nature and product chemistry of
the chemical stressor - Sulfometuron methyl.	  PAGEREF _Toc191187616 \h 
15  

  HYPERLINK \l "_Toc191187617"  Table 3.  Taxonomic Groups, Test Species
and Acute Toxicity Classification for Assessing Ecological Risks of
Sulfometuron Methyl to Non-target Organisms.	  PAGEREF _Toc191187617 \h 
18  

  HYPERLINK \l "_Toc191187618"  Table 4.  Measures of Ecological Effects
and Exposure for Sulfometuron Methyl	  PAGEREF _Toc191187618 \h  26  

  HYPERLINK \l "_Toc191187619"  Table 5. Permitted application methods
for sulfometuron methyl, DuPont Products	  PAGEREF _Toc191187619 \h  28 

  HYPERLINK \l "_Toc191187620"  Table 6. Permitted application methods
for sulfometuron methyl, Vegetation Management LLC Products	  PAGEREF
_Toc191187620 \h  28  

  HYPERLINK \l "_Toc191187621"  Table 7.  States with high sulfometuron
usage (based upon DuPont sales data, 2001-2004).	  PAGEREF _Toc191187621
\h  28  

  HYPERLINK \l "_Toc191187622"  Table 8.  Annual usage of sulfometuron
methyl in the US by use site.	  PAGEREF _Toc191187622 \h  29  

  HYPERLINK \l "_Toc191187623"  Table 9.  Sulfometuron application rate
ranges by product label and use site.	  PAGEREF _Toc191187623 \h  30  

  HYPERLINK \l "_Toc191187624"  Table 10. Key results of sulfometuron
methyl environmental fates studies.	  PAGEREF _Toc191187624 \h  35  

  HYPERLINK \l "_Toc191187625"  Table 11.  Models Used to Estimate
Exposure Concentrations for Aquatic Ecosystem.	  PAGEREF _Toc191187625
\h  44  

  HYPERLINK \l "_Toc191187626"  Table 12. Aquatic exposure with PRZM –
EXAMS: Modeling scenarios and representative usage pattern summary.	 
PAGEREF _Toc191187626 \h  45  

  HYPERLINK \l "_Toc191187627"  Table 13.  PRZM/EXAMS input parameters
for modeling (Aquatic ecological EECs).	  PAGEREF _Toc191187627 \h  46  

  HYPERLINK \l "_Toc191187628"  Table 14.  Estimated environmental
concentrations (µg/L) for aquatic exposure to parent sulfometuron
methyl: scenario-specific results from PRZM-EXAMS modeling.	  PAGEREF
_Toc191187628 \h  48  

  HYPERLINK \l "_Toc191187629"  Table 15.  Sulfometuron methyl surface
water EECs used in aquatic risk assessment.	  PAGEREF _Toc191187629 \h 
50  

  HYPERLINK \l "_Toc191187630"  Table 16. Estimated concentrations of
sulfometuron methyl in ground water (SCI-GROW inputs and results).	 
PAGEREF _Toc191187630 \h  50  

  HYPERLINK \l "_Toc191187631"  Table 17.  Unadjusted Dietary
Terrestrial EECs for Birds and Mammals Following Sulfometuron Methyl
Spray Application For Non-Crop Vegetative Management.	  PAGEREF
_Toc191187631 \h  52  

  HYPERLINK \l "_Toc191187632"  Table 18.   EECs for Terrestrial Plants
Located Adjacent to Sulfometuron Methyl (aerial and ground spray
application) Treated Sites.	  PAGEREF _Toc191187632 \h  53  

  HYPERLINK \l "_Toc191187633"  Table 19.  Selected AgDRIFT inputs for
high-end exposure from aerial applications of sulfometuron methyl using
best management practices.	  PAGEREF _Toc191187633 \h  54  

  HYPERLINK \l "_Toc191187634"  Table 20.  Estimated percentage of
sulfometuron methyl spray drift from ground or aerial applications at
various distances from a treated field.	  PAGEREF _Toc191187634 \h  55  

  HYPERLINK \l "_Toc191187635"  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.	  PAGEREF _Toc191187635 \h  56  

  HYPERLINK \l "_Toc191187636"  Table 22.  The Most Sensitive Endpoints
Used In The Sulfometuron Methyl Screening-Level Risk Estimation.	 
PAGEREF _Toc191187636 \h  59  

  HYPERLINK \l "_Toc191187637"  Table 23.  Freshwater Fish Acute
Toxicity of Sulfometuron Methyl.	  PAGEREF _Toc191187637 \h  60  

  HYPERLINK \l "_Toc191187638"  Table 24.  Freshwater Invertebrate Acute
Toxicity of Sulfometuron Methyl.	  PAGEREF _Toc191187638 \h  60  

  HYPERLINK \l "_Toc191187639"  Table 25.  Estuarine/Marine Fish Acute
Toxicity of Sulfometuron Methyl.	  PAGEREF _Toc191187639 \h  61  

  HYPERLINK \l "_Toc191187640"  Table 26.  Freshwater Invertebrate Acute
Toxicity of Sulfometuron Methyl.	  PAGEREF _Toc191187640 \h  62  

  HYPERLINK \l "_Toc191187641"  Table 27.  Freshwater Aquatic
Invertebrate Chronic Toxicity for Sulfometuron Methyl.	  PAGEREF
_Toc191187641 \h  63  

  HYPERLINK \l "_Toc191187642"  Table 28.  Non-target Aquatic Plant
Toxicity for Sulfometuron Methyl.	  PAGEREF _Toc191187642 \h  66  

  HYPERLINK \l "_Toc191187643"  Table 29.  Avian Acute Oral Toxicity for
Sulfometuron Methyl.	  PAGEREF _Toc191187643 \h  67  

  HYPERLINK \l "_Toc191187644"  Table 30.  Avian Subacute Dietary
Studies for Sulfometuron Methyl.	  PAGEREF _Toc191187644 \h  67  

  HYPERLINK \l "_Toc191187645"  Table 31.  Mammalian Acute Toxicity for
Sulfometuron Methyl.	  PAGEREF _Toc191187645 \h  68  

  HYPERLINK \l "_Toc191187646"  Table 32.  Non-Target Insects - Acute
Contact Toxicity for Sulfometuron Methyl.	  PAGEREF _Toc191187646 \h  68
 

  HYPERLINK \l "_Toc191187647"  Table 33.  Mammalian Developmental
Toxicity of Sulfometuron Methyl .	  PAGEREF _Toc191187647 \h  69  

  HYPERLINK \l "_Toc191187648"  Table 34.  Mammalian Acute Toxicity to
Sulfometuron Methyl in Formulated Product: DPX-T5486-87	  PAGEREF
_Toc191187648 \h  70  

  HYPERLINK \l "_Toc191187649"  Table 35.  Summary of Most Sensitive
Tier II Terrestrial Non-target Plant Seedling Emergence and Vegetative
Vigor Toxicity Data for Sulfometuron Methyl.	  PAGEREF _Toc191187649 \h 
72  

  HYPERLINK \l "_Toc191187650"  Table 36.  Risk Presumptions for Aquatic
Animals.	  PAGEREF _Toc191187650 \h  74  

  HYPERLINK \l "_Toc191187651"  Table 37.  Risk Presumptions for
Terrestrial Animals.	  PAGEREF _Toc191187651 \h  74  

  HYPERLINK \l "_Toc191187652"  Table 38.  Risk Presumptions for Plants.
  PAGEREF _Toc191187652 \h  74  

  HYPERLINK \l "_Toc191187653"  Table 39.  Endpoints Used for Estimating
Risks of Sulfometuron Methyl to Aquatic Animals and Plants.	  PAGEREF
_Toc191187653 \h  75  

  HYPERLINK \l "_Toc191187654"  Table 40.  Summary of Acute Aquatic
Plant Risk Quotients for Rights of Way Uses.	  PAGEREF _Toc191187654 \h 
76  

  HYPERLINK \l "_Toc191187655"  Table 41.  Endpoints Used for Estimating
Risks of Sulfometuron Methyl to Terrestrial Animals.	  PAGEREF
_Toc191187655 \h  77  

  HYPERLINK \l "_Toc191187656"  Table 42.  Upper Bound Kenaga, Acute
Avian Dose-Based Risk Quotients (Bounding Analysis Only).	  PAGEREF
_Toc191187656 \h  78  

  HYPERLINK \l "_Toc191187657"  Table 43. Upper Bound Kenaga, Subacute
Dietary-Based Risk Quotients (Bounding Analysis Only).	  PAGEREF
_Toc191187657 \h  78  

  HYPERLINK \l "_Toc191187658"  Table 44.   Upper Bound Kenaga, Acute
Mammalian Dose-Based  Risk Quotients (Bounding Analysis Only).	  PAGEREF
_Toc191187658 \h  79  

  HYPERLINK \l "_Toc191187659"  Table 45.  Upper Bound Kenaga, Chronic
Mammalian Dose-Based Risk Quotients.	  PAGEREF _Toc191187659 \h  79  

  HYPERLINK \l "_Toc191187660"  Table 46.  Upper Bound Kenaga, Chronic
Mammalian Dietary-Based Risk Quotients	  PAGEREF _Toc191187660 \h  80  

  HYPERLINK \l "_Toc191187661"  Table 47.  Summary of Selected Endpoints
from Terrestrial Plant Toxicity Studies of Sulfometuron Methyl	  PAGEREF
_Toc191187661 \h  81  

  HYPERLINK \l "_Toc191187662"  Table 48.  RQ Values For Plants In Dry
And Semi-Aquatic Areas Exposed To Sulfometuron Methyl Through Runoff
And/Or Spray Drift.	  PAGEREF _Toc191187662 \h  81  

  HYPERLINK \l "_Toc191187663"  Table 49.  Risk Quotients for Non-target
and Endangered Plants, Resulting From Exposure to Sulfometuron Methyl in
Irrigation Water	  PAGEREF _Toc191187663 \h  82  

  HYPERLINK \l "_Toc191187664"  Table 50.  Toxicity of sulfometuron
methyl to the African clawed frog from a study by Fort et al.  (1999).	 
PAGEREF _Toc191187664 \h  86  

  HYPERLINK \l "_Toc191187665"  Table 51.  ECOSAR-predicted toxicity
values for major degradates of sulfometuron methyl.	  PAGEREF
_Toc191187665 \h  88  

  HYPERLINK \l "_Toc191187666"  Table 52.  Risks to Terrestrial Plants
from Spray Drift According to Distance Downwind, Application Method, and
Drift Exposure Conditions	  PAGEREF _Toc191187666 \h  95  

  HYPERLINK \l "_Toc191187667"  Table 53.  Listed Taxonomic Groups
Potentially at Risk from Direct or Indirect Effects of Sulfometuron
Methyl Application for Vegetative Management Throughout the U.S.	 
PAGEREF _Toc191187667 \h  104  

 

LIST OF FIGURES

  TOC \h \z \c "Figure"    HYPERLINK \l "_Toc191187668"  Figure 1.
Conceptual model for sulfometuron methyl fate and effects in aquatic
ecosystems.	  PAGEREF _Toc191187668 \h  22  

  HYPERLINK \l "_Toc191187669"  Figure 2. Conceptual model for
sulfometuron methyl fate and effects in terrestrial ecosystems.	 
PAGEREF _Toc191187669 \h  23  

  HYPERLINK \l "_Toc191187670"  Figure 3. Chronic Toxicity of
Sulfonylurea Herbicides to Freshwater Fish	  PAGEREF _Toc191187670 \h 
84  

  HYPERLINK \l "_Toc191187671"  Figure 4. Chronic Avian Toxicity of
Sulfonylurea Herbicides	  PAGEREF _Toc191187671 \h  91  

 

EXECUTIVE SUMMARY  TC \l1 "I.  EXECUTIVE SUMMARY 

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 EC50s/ LC50s 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 (EC50/ LC50s 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 EC50 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 EC50 and NOAEC values of
4.6 and 0.63 μg/L, respectively, based on cell density.  

Sulfometuron methyl is practically non-toxic to birds (LD50 >4,650
mg/kg-bw; LC50 >4,600 mg/kg-diet), mammals (LD50 >5000 mg/kg-bw), and
bees (LD50 >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).  

 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   HYPERLINK
"http://www.agdrift.com/AgDRIFt2/DownloadAgDrift2_0.htm" 
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  
REF _Ref179644072 \w \h  \* MERGEFORMAT  3.2.3.1  and   REF
_Ref179645835 \w \h  \* MERGEFORMAT  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 
 HYPERLINK "http://www.agdrift.com/AgDRIFt2/DownloadAgDrift2_0.htm" 
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.  

Table   SEQ Table \* ARABIC  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 Effects	Basis for Direct Effects Concern	Indirect
Effects	Basis for Indirect Effects Concern

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

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

Birds and Reptiles1	No	The LOC is not exceeded	Yes	Potential concerns
for birds and reptiles that use plants for habitat, feeding, or cover
requirements.

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

Mammals

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

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

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

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

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

(1) Birds are used as surrogate species for terrestrial-phase amphibians
and reptiles; therefore, potential direct and indirect effects to
endangered avian, terrestrial-phase amphibians and reptilian species are
considered equivalent.

(2) Fish are used as a surrogate for aquatic phase amphibians;
therefore, potential direct and indirect effects to endangered 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

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   REF _Ref184022003 \h  Table 2 . 

Table   SEQ Table \* ARABIC  2 . Nature and product chemistry of the
chemical stressor - Sulfometuron methyl.

Common name	Sulfometuron methyl

IUPAC Chemical Name	2-(4,6-Dimethylpyrimidin-2-ylcarbamoylsulfamoyl)
benzoic acid, methyl ester

OR

2-[3-(4,6-dimethylpyrimidin-2-yl)ureidosulfonyl] benzoic acid, methyl
ester

CAS Chemical Name	2-[[[[(4,6-Dimethyl-2-pyrimidinyl) amino] carbonyl]

Pesticide type	Herbicide

Chemical class	Sulfonylurea herbicide

CAS number	74222-97-2

Empirical formula	C15H16N4SO5

Molecular Mass (g/mol)	364.38

Vapor pressure at 20o C	5.4 x10-16 Torr

Henry’s Law Constant at 20o C

(atm m3/mol)	1.1 x 10-18, calculated

from vapor pressure

Solubility in water (mg/L)at 200C	pH 5 buffer...... 6.42 ppm

pH 7 buffer ...... 244 ppm

pH 8.6 buffer.. 12,500 ppm

Log Kow 	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:

Hydrolytic cleavage generating a sulfonamide plus the aminopyrimidine
(resulting in elimination of a carbon dioxide molecule)

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:   HYPERLINK
"http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm" 
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   HYPERLINK
"http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.
htm" 
http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.h
tm  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.  T  SEQ CHAPTER \h \r 1 oxicological
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 (
 HYPERLINK "http://cfpub.epa.gov/ecotox/"  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.  

  REF _Ref177716963 \h  \* MERGEFORMAT  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.

Major environmental degradates of sulfometuron methyl most commonly
include: the sulfometuron sulfonamide, the sulfometuron pyrimidine
amine, and saccharin; other degradates occur less commonly (see   REF
_Ref184020399 \h  Table 10  and   REF _Ref177717834 \h  \* MERGEFORMAT 
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. 

Table   SEQ Table \* ARABIC  3 .  Taxonomic Groups, Test Species and
Acute Toxicity Classification for Assessing Ecological Risks of
Sulfometuron Methyl to Non-target Organisms.

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

Birds1	  SEQ CHAPTER \h \r 1 Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)	Practically non-toxic

  SEQ CHAPTER \h \r 1 Mammals	  SEQ CHAPTER \h \r 1 Laboratory rat
(Rattus norvegicus)	Practically non-toxic

  SEQ CHAPTER \h \r 1 Insects	  SEQ CHAPTER \h \r 1 Honey bee (Apis
mellifera L.)	Practically non-toxic

  SEQ CHAPTER \h \r 1 Freshwater fish2		  SEQ CHAPTER \h \r 1 Bluegill
sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)	Practically non-toxic

Practically non-toxic

  SEQ CHAPTER \h \r 1 Freshwater invertebrates	  SEQ CHAPTER \h \r 1
Water flea (Daphnia magna)	Practically non-toxic

  SEQ CHAPTER \h \r 1 Estuarine/marine fish	  SEQ CHAPTER \h \r 1 
Sheepshead minnow (Cyprinodon variegatus)	> Slightly toxic4

Estuarine/marine invertebrates	Mysid shrimp (Mysidopsis bahia)

Eastern oyster (Crassostrea virginica)	> Slightly toxic4 

> Slightly toxic4

  SEQ CHAPTER \h \r 1 Terrestrial plants3	  SEQ CHAPTER \h \r 1 Monocots
– corn (Zea mays)

Dicots – soybean (Glycine max)	Not classified

  SEQ CHAPTER \h \r 1 Aquatic plants and algae	  SEQ CHAPTER \h \r 1
Duckweed (Lemna gibba) 

Green algae (Selenastrum capricornutum)

Bluegreen algae (Anabaena flos-aquae)

Diatom (Navicula pelliculosa)

	Not classified

  SEQ CHAPTER \h \r 1 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   REF _Ref178558153 \r \h  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   REF _Ref179505907 \h  Figure 1  and   REF
_Ref179505925 \h  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 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 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.

 

 

Figure   SEQ Figure \* ARABIC  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.

 

Figure   SEQ Figure \* ARABIC  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  tc \l2 "E.        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   HYPERLINK
"http://www.epa.gov/oppefed1/ecorisk_ders/toera_analysis_exp.htm#WSAN2" 
http://www.epa.gov/oppefed1/ecorisk_ders/toera_analysis_exp.htm#WSAN2 
and   HYPERLINK
"http://www.oecd.org/department/0,3355,en_2649_34377_1_1_1_1_1,00.html" 
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  tc \l3 "1.         Preliminary
Identification of Data Gaps and Methods 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 LD50 or NOAEC. 
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 
 REF _Ref178576262 \h  Table 4  are selected for this baseline risk
assessment.

	

Table   SEQ Table \* ARABIC  4 .  Measures of Ecological Effects and
Exposure for Sulfometuron Methyl

Assessment Endpoint

	

Surrogate Species and Measures of Ecological Effect1	

Measures of Exposure

Birds2	Survival

	Bobwhite acute oral LD50

Bobwhite and mallard subacute dietary LC50	

Maximum residues on food items (foliar)

	Reproduction and growth	Bobwhite and mallard chronic reproduction NOAEC
and LOAEC

 (no studies available)

	Mammals	Survival	Laboratory rat acute oral LD50

	

Reproduction and growth	Laboratory rat oral reproduction chronic NOAEC
and LOAEC  

(no acceptable studies available)

	Freshwater fish3

	Survival	Rainbow trout and bluegill sunfish acute LC50 	Peak EEC4

	Reproduction and growth	Fathead minnow

        chronic (early life-stage) NOAEC and LOAEC

(no acceptable studies available)	60-day average EEC4

Freshwater invertebrates	Survival	Water flea acute EC50	Peak EEC4

	Reproduction and growth	Water flea chronic (life cycle) LOAEC	21-day
average EEC4

Estuarine/marine fish

	Survival	Sheepshead minnow acute LC50 	Peak EEC4

	Reproduction and growth	Sheepshead minnow chronic (early life-stage)
NOAEC and LOAEC

(No studies available)	60-day average EEC4

Estuarine/marine invertebrates	Survival	Eastern oyster acute EC50 and
mysid acute LC50	Peak EEC4

	Reproduction and growth	Mysid chronic NOAEC and LOAEC

(no data available)	21-day average EEC4

Terrestrial plants5	Survival and growth	Monocot and dicot seedling
emergence and vegetative vigor EC25, EC05, and NOAEC values	Estimates of
runoff and spray drift to non-target areas

Insects

	Survival (not quantitatively assessed)	Honeybee acute contact LD50 
Maximum application rate

Aquatic plants and algae	Survival and growth	Algal and vascular plant
(i.e., duckweed) EC50 and NOAEC values for growth rate and biomass
measurements	Peak EEC

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).
LD50 = Lethal dose to 50% of the test population; NOAEC = No observed
adverse effect concentration; LOAEC = Lowest observed adverse effect
concentration; LC50 = Lethal concentration to 50% of the test
population; EC50/EC25 = Effect concentration to 50%/25% of the test
population.



ANALYSIS	

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 (  REF _Ref184020171 \h 
Table 5  and   REF _Ref184020188 \h  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 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   REF _Ref177866558 \h  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 (  REF _Ref177654603 \h  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   REF
_Ref177740523 \h  Table 8 .

Table   SEQ Table \* ARABIC  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).

Table   SEQ Table \* ARABIC  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).

Table   SEQ Table \* ARABIC  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, GA, VA	AR, MS, AL	 ---	 ---

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

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

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

Table   SEQ Table \* ARABIC  8 .  Annual usage of sulfometuron methyl in
the US by use site.

Use Site	Low Estim.	High Estim.

	Annual Usage,

Lbs ai

 (Commercial Christmas Trees - Nurseries) 	50	830

 Forestry 	89,000	100,000

 Non-crop Vegetative Management (VM - includes Roadway, Utility &
Pipeline) 	80,000	100,000

 Railroad (RR) 	50,000	71,000

 Total 	230,000	261,000

 Estimates reflect ranges from combined registrant and 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.

Table   SEQ Table \* ARABIC  9 .  Sulfometuron application rate ranges
by product label and use site.

Product Name	Type of Formulation	Additional Active Ingredient(s)	Use
Site(s)	Single App.  Low Rate (pounds a.i.)	Single App.  High Rate
(pounds a.i.)

DuPont™ Oust® 

Herbicide

Or “Sulfometuron methyl 75”	Dispersible granules	None (may be tank
mixed)	Forestry

Non-Crop	0.047

0.047	0.375

0.375

DuPont™ Oust® XP Herbicide	Dispersible granules	None (may be tank
mixed)	Forestry 

Non-Crop	0.023

0.047	0.375

0.375

DuPont™ 

Oust®  Extra Herbicide	Dispersible granules	Metsulfuron Methyl	Conifer
Plantations

Non-Crop	0.023

0.016	0.281

0.188

DuPont™ Oustar® 

Herbicide	Dispersible granules	Hexazinone

	Forestry	0.075

	0.175

DuPont™ Westar® 

Herbicide	Dispersible granules	Hexazinone

	Christmas Trees

Forestry

Non-Crop	0.025

0.100

0.131	0.100

0.131

0.194

DuPont™ Landmark® MP Herbicide	Dispersible granules	Chlorsulfuron
Non-Crop 	0.023	0.281

DuPont™ Landmark® II MP Herbicide	Dispersible granules	Chlorsulfuron
Non-Crop 	0.035	0.350

DuPont™ Landmark® XP Herbicide	Dispersible granules	Chlorsulfuron
Non-Crop 	0.023	0.281

DuPont™ Landmark® II XP Herbicide	Dispersible granules	Chlorsulfuron
Non-Crop 	0.035	0.350

DuPont™ 

Throttle™ MP Herbicide	Dispersible granules	Sulfentrazone

Chlorsulfuron	Non-Crop **	0.141	0.141

DuPont™ 

Throttle™ XP

Herbicide	Dispersible granules	Sulfentrazone

Chlorsulfuron	Non-Crop	0.141	0.141

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Conifer Site
Preparation (pre-plant)	0.063	0.250

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Conifer
Release (post-transplant)	0.125	0.188

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Conifer Site
Preparation or Post-transplant for specific weeds (e.g., Kudzu)	0.281
0.375

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Hardwoods
(seedlings or transplants in dormancy)	0.023	0.234

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Non-Crop:

“Non-Agricultural”*	0.035	0.375

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Non-Crop: 

Under asphalt and concrete pavements (before paving)	0.188	0.375

SFM 75, SFM Extra	Dispersible granules	Only in  tank mixes	Non-crop:

Turf (unimproved)	0.023	0.188

** Non-Crop lumps together uses such as rights-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 (  REF _Ref184020399 \h 
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 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). 
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
KF 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 (“NHSO2 acid herbicides” means sulfonylurea
herbicides):

OM and pH were also the primary soil properties in best-fit Kd equations
obtained for five of the six NHSO2 acid herbicides, with all three soil
properties utilized in the Kd equation for sulfometuron-methyl. Cl was
also one component of the Kd 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:

Kd = 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 Kd of any of ten families of
pesticides tested; the correlation of soil percent OM and Kd was second
to “OH acid” (uracil) herbicides such as bromacil. Similarly, soil
pH and % OM together accounted for more of the variability in soil Kd
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   REF _Ref178226314 \r \h  \* MERGEFORMAT 
3.2.2.2 ,   REF _Ref178226222 \h  \* MERGEFORMAT  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 CO2 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 “  REF _Ref178038010 \h  \* MERGEFORMAT  APPENDIX A:
Structures and Chemical Names of Sulfometuron methyl Metabolites ”).
For the phenyl ring labeled studies, CO2 was up to 28 to 44 % of applied
at study termination whereas for the pyrimdine-ring labeled studies CO2
was up to 53% of applied at study termination (see   REF _Ref184020399
\h  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 Kfs were 0.03 to 0.27 and the
pyrimidine amine Kfs were 0.17 to 3.70 in the four test soils (  REF
_Ref184020399 \h  Table 10 ). This means saccharin would be slightly
more mobile and the pyrimidine amine slightly less mobile than parent
(Kfs of 0.15 to 2.12 in the same four soils)

Table   SEQ Table \* ARABIC  10 . Key results of sulfometuron methyl
environmental fates studies.

Parameter

[Guideline #]	Value1	MRID(s)

Hydrolysis

[161-1]

	t½= 8.8 days @ 25 oC, pH 5;

t½=139 days @ 25 oC, pH 7;

t½= 224 days @ 25 oC, pH 9.

	

Major degradates (from cleavage of the sulfonylurea bridge): 

Sulfonamide – only in acidic water

Saccharin – all pH levels

Pyrimidine amine – all pH levels

	

42715201

Direct photolysis in water

[161-2]	Combined labels results:

t½= 428 days @ 24 oC, pH 5;

t½= stable @ 24 oC, pH 7;

t½= stable @ 24 oC, 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.

	

42182401

43174101

Photolysis on soil

[161-3]	t½= 72.1 days @ 25 oC, 

Study duration was 33 days, substantial degradation occurred in dark
controls and the calculated photolysis half-life represents the
difference in the dissipation rate in the irradiated and the dark
control samples.

Major degradates (from cleavage of the 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
14C-labeled.	

41420601

Aerobic soil metabolism

[162-1]

	Study with [pyrimidine-2-14C] Sulfometuron Methyl

Soil: Keyport Silt loam (pH 6.3, 1.6% O.C.) from Delaware

First Order t½:			57.8 days (r2 = 0.9239).

Observed DT50:		23 days.

Observed DT90:		110 days.

Sterile soil First Order t½: 	364 days

Major transformation products:

Pyrimidine amine (maximum 41.0% of the applied)

Pyrimidine-ol (maximum 10.5% of the applied).

	CO2 (maximum 53.1% of applied).

Minor transformation products:	

Free acid sulfometuron methyl.

Pyrimidine urea. 

	

42091401

Aerobic soil metabolism

[162-1]

	Study with U- 14C-phenyl-labeled Sulfometuron Methyl

Soil: Keyport Silt loam (pH 6.4, 1.6 % O.C.) from Delaware (0.12 mg
a.i./kg).

First Order t½:		52.5 days (r2 = 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).

	CO2.

Minor transformation products:	

Free acid sulfonamide plus urea (0.12 mg a.i./Kg only)

	

43174102 and 245375

Anaerobic aquatic metabolism

[162-3]	Study  performed with [pyrimidine-2-14C] Sulfometuron Methyl

Matrix: Bradenton Pond water-sand sediment.

First Order t½:			37.4 days (r2 = 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 t½; total system:	17.1 days (r2 = 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.

CO2.	

42091402 and 43188601

Anaerobic aquatic metabolism

[162-3]	Study with [phenyl-U-14C] Sulfometuron Methyl

Matrix: Pond water-sandy loam sediment from Bradenton, Florida.

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

First Order t½; total system:	104 days (r2 = 0.4883)*.

Observed DT50 in total system:	ca. 21 days.

Sterile t½; 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 t½; total system:	87 days (r2 = 0.3577).

Observed DT50 in total system:	ca. 28 days.

Sterile t½; 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 t½; total system:	77 days (r2 = 0.5853).

Observed DT50 in total system:	ca. 70 days.

Sterile t½; 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 t½; total system:	73 days (r2 = 0.5691).

Observed DT50 in total system:	ca. 28 days.

Sterile t½; total system:	95 days

Major transformation products:

	saccharin.

	free acid sulfonamide.

Minor identified transformation products:

	Methyl-2-aminocarbonyl(aminosulfonyl)benzoate.	

4413010-20 (143540)

Aerobic aquatic metabolism

[162-4]	Study  performed with [pyrimidine-2-14C] Sulfometuron Methyl

Matrix used: Pond water-silt loam sediment (Landenberg, acidic system).

First Order t½; total system:	9.2 days (r2 = 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:

CO2.

Matrix used: Pond water-sand sediment (Bradenton, alkaline system).

First Order t½; total system:	187.3 days (r2 = 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).

CO2.	

42091403 and 43174103

Adsorption/

Desorption 

(Kd and 

Koc in L Kg-1)

	Parent sulfometuron methyl:

Soil type:  Chino Sandy loam; pH 7.1, organic carbon 1.0%.

Adsorption Kd:			0.35.

Adsorption Koc:			35.

Freundlich adsorption KF:	0.153.

Freundlich adsorption KFoc:	14.7.

1/N				0.504

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

Adsorption Kd:			2.07.

Adsorption Koc:			79.6.

Freundlich adsorption KF:	2.12.

Freundlich adsorption KFoc:	83.2.

1/N				1.23

Soil type:  Miaka Sand ; pH 7.0, organic carbon 0.6%.

Adsorption Kd:			Not applicable.

Adsorption Koc:			Not applicable.  

Freundlich adsorption KF:	0.508.

Freundlich adsorption KFoc:	87.6.

1/N				1.61

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

Adsorption Kd:			0.79.

Adsorption Koc:			52.7.

Freundlich adsorption KF:	0.974.

Freundlich adsorption KFoc:	67.2.

1/N				0.851

	42789301

Adsorption/

Desorption 

Of Degradates	

  SEQ CHAPTER \h \r 1 Pyrimidine amine 

Although the registrant conducted adsorption / desorption studies for
the pyrimidine amine degradate, the results were insufficiently
documented to verify their calculations of adsorption coefficients (and
furthermore, they only reported Freundlich adsorption “KF” and
“KFoc” values without 1/N values (or sufficient data for the
reviewer to calculate them) and Kd 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 Kd values of 0.23 to 1.52 and Koc
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.

  SEQ CHAPTER \h \r 1 Saccharin

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 “KF” and “KFoc” values without
1/N values and Kd values were also not reported.

Saccharin has been reported elsewhere to be quite mobile, e.g.:

When tested as a degradate of metsulfuron methyl (  HYPERLINK
"http://ec.europa.eu/food/plant/protection/evaluation/existactive/list1-
13_en.pdf" 
http://ec.europa.eu/food/plant/protection/evaluation/existactive/list1-1
3_en.pdf  )

	

42789301

Terrestrial Field/Lysimeter

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

Half-life: 49.2 days (based on 0- to 359-day data); 

12.2 days (based on 0- to 91-day data).

DT90:	32 days

Major transformation products detected (>0.01 ppm): 

Sulfometuron free acid (SFA)

Pyrimdine amine (PYA)

Sulfonamide IN-D5803 (SFN)

Saccharin IN-581 (SCC)

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

Half-life: 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	Numbers 43212101 and 43637101

1 Unless otherwise specified, half-lives were derived with a
“Log-linear” degradation rate calculation; a process of calculating
degradation rates and half-lives from linear regression of
log-transformed concentration measurements over time. This provides a
first-order type of measurement of pesticide decline.

2 For these field dissipation studies, differences between half-lives
measured over various time durations apparently reflect both slowing of
degradation at lower temperatures and a large variability in measured
concentrations; also, a 2-compartment degradation model for adsorbed and
dissolved sulfometuron is quite possibility more appropriate (little
dissipation of the remaining residues in the topsoil occurred during the
second year of these studies, for example). A 2-compartment model was
not used to represent dissipation rate here because the data are not
sufficient robust (e.g., very high variability between replicate
measurements), the effects of weather changes on degradation rate cannot
easily be isolated, and the amount of residues lost through dissipation
out of the topsoil also cannot be separated from the amount lost to
degradation. At all four of these field study sites about 99% of the
applied sulfometuron methyl dissipated from the topsoil within 3 to 6
months.

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 95th 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 (Pesticide Root Zone Model) and EXAMS (EXposure Analysis
Modeling System) models (  REF _Ref178047312 \h  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-m2 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   HYPERLINK
"http://www.epa.gov/oppefed1/models/water/index.htm" 
http://www.epa.gov/oppefed1/models/water/index.htm ).  Potential
exposure from ground-water (for, example, via contaminated irrigation
water) was also estimated using the SCI-GROW model.

Table   SEQ Table \* ARABIC  11 .  Models Used to Estimate Exposure
Concentrations for Aquatic Ecosystem.

Exposure Estimate Type	Models Used

Aquatic ecosystems

Surface water (Tier II)

	

PE v5.0, PRZM v3.12.2, EXAMS v2.98.04.06 

Details of executables:

PRZM 3.12.2, named przm3122.exe (dated May 12, 2005) 

EXAMS 2.98.04.06, executable file named EXAMS.EXE (dated April 12, 2005)

PE v5.0,  Executable file PE5.pl (dated July 24, 2006)

Ground water (Tier I)	SCI-GROW v2.3

Executable file sg23.exe (dated May 16, 2006)

The estimated environmental concentrations (EECs) were predicted
assuming 1 aerial or ground application at 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   REF _Ref177973597 \w \h  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   REF
_Ref177973831 \h  Table 12 ).  The major adjustments to the standard
scenario modeling were:

 

1.  Specific regional scenario adjustments. The rights-of-way regional
scenarios were selected for this national assessment because they are
the only scenarios currently approved in EFED for specific modeling of
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.  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.
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 90th 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
  REF _Ref177972956 \h  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 (  REF _Ref177972956
\h  \* MERGEFORMAT  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   REF _Ref178575384 \r \h  \* MERGEFORMAT  3.2.4.3 . 

Table   SEQ Table \* ARABIC  12 . Aquatic exposure with PRZM – EXAMS:
Modeling scenarios and representative usage pattern summary.

Scenario ID1	WBAN (met. file)2	appl. meth.	CAM3	applictn. dates (MM-DD)
Use(s) represented

PA Apples (std)	W14751	Aerial	2	03-15	Forestry, Conifer Plantations

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

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

FL Turf (std)	W12834	Ground	1	03-01	Non-crop (e.g., unimproved turf &
rights of way)

FL Turf (std)	W12834	Aerial	2	03-01	Unimproved turf, non-crop

PA Turf (std)	W14751	Aerial	2	03-01	Unimproved turf, non-crop

OR Xmas Trees (std)	W24232	Ground	1	03-01	Christmas Trees, Forestry,
Conifer Plantations

OR Xmas Trees (std)	W24232	Aerial	2	03-01	Christmas Trees, Forestry,
Conifer Plantations

CA right of way (RLF)	W23234	Aerial 	2	03-01	Non-Crop (rights of way,
unimproved turf, railroads, etc.)

CA right of way (RLF)	W94224	Aerial	2	03-01	Non-Crop (rights of way,
unimproved turf, railroads, etc.)

CA right of way (RLF)	W94224	Aerial	2	Feb to Oct4 	Non-Crop (rights of
way, unimproved turf, railroads, etc.)

TX right of way (BSS)	W13958	Aerial	2	03-01	Non-Crop (rights of way,
unimproved turf, railroads, etc.)

TX right of way (BSS)	W12917	Aerial	2	03-01	Non-Crop (rights of way,
unimproved turf, railroads, etc.)

TX right of way (BSS)	W12917	Aerial	2	Feb to Oct4 	Non-Crop (rights of
way, unimproved turf, railroads, etc.)

TX right of way (BSS)	W12917	Ground	2	Feb to Oct4 	Non-Crop (rights of
way, unimproved turf, railroads, etc.)

1 Native scenario designation state and use site.  Native scenario
target in parenthesis, where: std = std scenario used in nationwide
assessments; RLF = scenario originally developed for regional
assessments related to the California red-legged frog; and BSS =
scenario originally developed for regional assessments related to the
Barton Springs salamander.

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

3 CAM = Chemical application method. CAM 1 is application direct to
soil, although a 4 cm incorporation depth is

automatically assumed, to account for surface roughness. CAM 2 is linear
foliar decay based on crop canopy, default soil incorporation depth for
non-foliar intercepted chemical is 4 cm.

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

 Table   SEQ Table \* ARABIC  13 .  PRZM/EXAMS input parameters for
modeling (Aquatic ecological EECs).

Input Parameter	Value*	Reference

Molecular Weight (gram mole -1)	364.38	MRID: 416728-02

Vapor Pressure (torr)	5.4x10-16

	Aerobic Soil Metabolism Half-life (days)	60.9	90% Upper Confidence
Limit of the mean of measured values  (MRIDs 42091401; 43174102 and
245375)

Water column Half-life (days)

(Aerobic Aquatic Metabolism half-life)	292	90% Upper Confidence Limit of
the mean of measured values  (MRIDs 42091403 and 43174103 )

Benthic sediment Half-life (days) 

(Anaerobic Aquatic Metabolism half-life)	76	90% Upper Confidence Limit
of the mean of measured values  (MRIDs 43174102, 245375, 42091402, and
43188601)

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

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

Application method; Depth of Incorporation (cm)	Aerial or ground;

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

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

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

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

Koc model was determined to be appropriate.

Hydrolysis Half-life @ pH 7 (days)	139 days	

MRID 42715201. 

Direct Aqueous Photolysis Half-life(days)	Stable	Maximum dark control
corrected value (MRIDs 42182401 and 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 (  REF
_Ref178047777 \h  Table 14 ).  Chosen EEC values for the aquatic risk
assessments are provided in   REF _Ref178044350 \h  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   SEQ Table \* ARABIC  14 .  Estimated environmental
concentrations (µg/L) for aquatic exposure to parent sulfometuron
methyl: scenario-specific results from PRZM-EXAMS modeling.

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

Scenario Description	Site1 	Peak	96 hr	21 Day	60 Day	90 Day	Yearly
Lifetime	Applictn. Date, mm-yy	App-Type3

PA Apple	Fr	2.28	2.23	2.05	1.61	1.39	0.45	0.31	3-15	aerial

FL Citrus	Fr	9.39	9.09	7.97	6.03	4.93	1.48	0.72	3-01	aerial

FL Citrus	Fr	7.32	7.08	6.19	4.71	3.81	1.14	0.43	3-01	ground

FL Turf	NC	1.47	1.43	1.27	1.01	0.86	0.29	0.20	3-01	aerial

FL Turf	NC	0.46	0.44	0.39	0.30	0.25	0.09	0.05	3-01	ground

PA Turf	NC	1.22	1.20	1.12	0.96	0.84	0.29	0.26	3-01	aerial

OR Xmas	Fr	1.57	1.53	1.42	1.21	1.06	0.40	0.29	3-01	aerial

OR(Astoria) Xmas	Fr	2.87	2.82	2.61	2.18	1.91	0.73	0.42	3-01	aerial

OR(Astoria) Xmas	Fr	1.78	1.74	1.58	1.29	1.13	0.43	0.35	9-01	aerial

CA RightsWay	NC	8.33	8.15	7.47	6.17	5.35	2.00	0.84	3-01	aerial

CA(As-OR) 4 RightsWay	NC	13.64	13.37	12.39	10.35	9.04	3.42	1.34	3-01
aerial

CA(As-OR) RightsWay 90th date5	NC	11.01	10.83	10.10	8.46	6.73	2.73	1.44
various 6	aerial

TX RightsWay	NC	6.96	6.74	5.99	4.72	3.94	1.22	0.64	3-01	aerial

TX(PtAr) 7 RightsWay	NC	11.87	11.55	10.66	8.84	7.41	2.30	1.06	3-01
aerial

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

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

TX(PtAr) RightsWay 90th date	NC	26.08	25.20	21.64	15.51	12.48	3.92	2.05
Various	ground

1 Fr = forestry plantings uses.  NC = Non-crop uses on rights of way,
industrial land with unimproved turf, on ground prior to paving,
railroads, etc.

2 CAF = crop area factor.

3 App-Type = application type.

4 As-OR = Astoria, Oregon meteorological weather substituted for the
original San Francisco, CA weather data for this regional scenario.

5 90th Date or 50th Date = For the specified exposure distribution the
90th percentile of the 10th 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.

6 Pt-Ar = Port Arthur, Texas meteorological weather substituted for the
original Austin, TX weather data for this regional scenario.

7 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.).



Table   SEQ Table \* ARABIC  15 .  Sulfometuron methyl surface water
EECs used in aquatic risk assessment.

Surface Water EECs in ug/L1

Application method	Peak	96-hr	21-day	60-day	90-day	Annual Average	Yearly
Average

Aerial	31.45	30.34	26.24	20.45	16.49	5.26	3.14

Ground	26.08	25.20	21.64	15.51	12.48	3.92	2.05

1 Results based on PRZM/EXAMS modeling described in Section   REF
_Ref178562606 \r \h  \* MERGEFORMAT  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.

Table   SEQ Table \* ARABIC  16 . Estimated concentrations of
sulfometuron methyl in ground water (SCI-GROW inputs and results).

Input Parameter	Value*	Reference

Aerobic Soil Metabolism Half-life (days)	55.2	Mean of measured values 
(MRIDs 42091401; 43174102 and 245375)

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

Application Number (Method of application)	    One	Typical use.

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

SCI-GROW Modeling Results

Acute Exposure EEC, ug/L 	0.33

	Chronic Exposure EEC, ug/L	0.33

	

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   REF _Ref177796826 \r \h 
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   REF _Ref177797625 \r \h  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., 90th 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 ( 
REF _Ref177798194 \h  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   REF
_Ref179708540 \h  APPENDIX F: T-REX Output 

Table   SEQ Table \* ARABIC  17 .  Unadjusted Dietary Terrestrial EECs
for Birds and Mammals Following Sulfometuron Methyl Spray Application
For Non-Crop Vegetative Management.

Uses	# of App. x App. Rate

(application method)	Food Items	Upper Bound EECs

(ppm)

Non-Crop Vegetative Management 1	1 x 0.375 lb a.i./A 

(ground broadcast)	Short Grass

Tall Grass

Sm. Insects, Broadleaf Plants

Lg. Insects, Fruits, Pods	90.0

41.3

50.6

5.6

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

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

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, t  SEQ CHAPTER \h \r 1 he amount of
sulfometuron methyl that runs off is a proportion of the application
rate and is assumed to be 5% based on a solubility of >100 mg/L for
sulfometuron methyl in 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   REF
_Ref177801664 \h  Table 18 . Details on inputs and outputs from the
TerrPlant model are provided in “  REF _Ref179701993 \h  APPENDIX D: 
Terrplant Spreadsheet ”.

 

Table   SEQ Table \* ARABIC  18 .   EECs for Terrestrial Plants Located
Adjacent to Sulfometuron Methyl (aerial and ground spray application)
Treated Sites.

Terrestrial Use	Application Method

(Non-granular)	EEC (lbs ai/A)

Total Loading to Dry Areas Adjacent to Treated Areas2	Total Loading to
Semi-Aquatic Areas Adjacent to Treated Areas3	Drift to Adjacent Areas4

Vegetative management1

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

	Ground (unincorporated)	0.023	0.19	0.0038

1 Includes uses on unimproved turf, forestry (Christmas trees & other
conifer plantations), non-crop vegetative management including
roadsides, railroads and industrial sites

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

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

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

Because sulfometuron methyl is an herbicide, a more in-depth spray drift
exposure assessment utilizing Tier I and II 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.    REF _Ref178147274 \h  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:

what may be characterized as typical applications that mostly follow
best management practices (that are recommended on the sulfometuron
label) – columns A and C. 

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:

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

Number of swaths = 20

Swath Width = 45 feet 

Application Efficiency (20 rows): 97.96 %

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   REF _Ref178145865 \h  Table 19 .  Factors
varied for the more typical-use scenario [D] with some best-management
practices  include:

Wind speed of 10 mph

ASAE droplet size of fine to medium

Temperature = 86 deg F

Relative Humidity = 75 percent

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   REF
_Ref178147274 \h  Table 20  and   REF _Ref178147279 \h  Table 21 .

Table   SEQ Table \* ARABIC  19 .  Selected AgDRIFT inputs for high-end
exposure from aerial applications of sulfometuron methyl using best
management practices.

                  

Input type	

Input value	

Justification

Aircraft	

Air Tractor AT-401	

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

Boom length	

76.3% of wingspan	

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

Release (boom) height 	

15 ft.	

Estimated upper bound under normal conditions.  Should be specified on
labels with no-spray zones.

Flight lines		

20	

Approximate standard scenario field size.

Swath width		

60 ft.	

Typical.  Does not greatly affect drift.

Swath displacement 

fraction (as a fraction of  the swath width)	

fine: 0.6833

	

Swath offset is good application practice.  The value used results in
50% deposition at the edge of the field.  

Drop size 

Distribution		

Fine (ASAE definition)	

Dependent upon product. 

Spray material	

50% water

50% nonvolatile	

Dependent on tank mix.  Calculate nonvolatile rate based on the portion
of the tank mix which is not easily evaporated (e.g. the fraction that
is not water or high vapor pressure solvent).  

Wind speed

(at 2 meters above the surface.	15 mph	

Typical wind speed varies greatly with geographic region and other
factors.  Ten mph is an adequate, high drift, input for many areas. 
Model runs for the plains states may require higher wind speeds.  Wind
speed 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 F	

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

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

Distance Down Wind (Feet)	[A] Ground Application (low boom)	[B] Ground
Application (high boom)	[C] Aerial (following many label
Recommendations)	[D] Aerial 

(high-end exposure scenario)

	Percent	Percent	Percent	Percent

0	102.0	106.0	50.00	77.35

50	1.77	5.00	17.12	38.32

100	0.95	2.48	9.79	25.11

200	0.51	1.20	4.69	14.07

500	0.21	0.39	1.92	5.40

750	0.13	0.22	1.39	3.82

900	0.11	0.17	1.24	3.32

Table   SEQ Table \* ARABIC  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.

Distance Down Wind (Feet)	[A] Ground Application (low boom)	[B] Ground
Application (high boom)	[C] Aerial (following many label
Recommendations)	[D] Aerial 

(high-end exposure scenario)

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

0	0.3822	0.3956	0.1874	0.2900

50	0.0066	0.0187	0.0642	0.1437

100	0.0036	0.0093	0.0367	0.0941

200	0.0019	0.0045	0.0176	0.0527

500	0.0008	0.0015	0.0072	0.0203

750	0.0005	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 “  REF _Ref178405615 \h  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 “  REF _Ref178405615
\h  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.

  REF _Ref178148115 \h  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. 

Table   SEQ Table \* ARABIC  22 .  The Most Sensitive Endpoints Used In
The Sulfometuron Methyl Screening-Level Risk Estimation.

Environment	Taxa	Type of Risk	Type of Endpoint	Endpoint	Units	MRID

Aquatic	Freshwater Fish	Acute	LC50	> 148	mg ai/L	435018-02

Chronic	NOAEC	Data gap

(A)

	Freshwater Invertebrates	Acute	EC50	> 150	mg ai/L	435018-03

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

	Saltwater Fish	Acute	LC50	> 45	

mg ai/L	

416728-03

	Saltwater Invertebrates	Acute	EC50	> 38.2	

mg ai/L	

416728-04

	Plants	Non-Listed	EC50	0.48	µg ai/L	435385-03

Listed	NOAEC	0.21	µg ai/L	435385-03

Terrestrial	Avian	Acute	LD50	> 4650	mg ai/kg-bw	245375

Acute	LC50	> 4600	mg ai/kg-diet	00071414

	Mammalian	Acute	LD50	> 5000 	mg ai/kg-bw	430892-01

Chronic	NOAEC	 > 300   	mg ai/kg-bw/d	78798

	Plants	Non-Listed	EC25	1.8 x 10-5	lb ai/A	435385-01(A)

Listed	EC5 (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 EC25, as
discussed in the terrestrial effect characterization section. 

Aquatic Effects Characterization  tc \l3 "1.     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., LC50 >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   REF _Ref178151784 \h  \*
MERGEFORMAT  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. 

Table   SEQ Table \* ARABIC  23 .  Freshwater Fish Acute Toxicity of
Sulfometuron Methyl.

Guideline	

Species 	% ai	96-hour

LC50 (mg/L) 	Toxicity Category	MRID No.

Author/Year	Study Classification

72-1	Bluegill sunfish 

(Lepomis macrochirus)	99.6	> 150	Practically

 non-toxic	435018-01

Brown (1994a)	Acceptable

72-1	Rainbow  trout

(Oncorhynchus mykiss)	99.6	> 148	Practically

non-toxic	435018-02

Brown (1994b)	Acceptable

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;   REF _Ref178151938 \h  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 “
 REF _Ref178405615 \h  APPENDIX H: Ecological Effects Data Summaries
.”

Table   SEQ Table \* ARABIC  24 .  Freshwater Invertebrate Acute
Toxicity of Sulfometuron Methyl.

Guideline	

Species 	% ai	48-hour

LC50 (mg/L) 	Toxicity Category	MRID No.

Author/Year	Study Classification

72-2	Water flea 

(Daphnia magna)	99.6	> 150	Practically

 Non-toxic	435018-03

Brown (1994c)	Acceptable(1)

(1) reclassified as acceptable for this risk assessment, see   REF
_Ref178405615 \h  \* MERGEFORMAT  APPENDIX H: Ecological Effects Data
Summaries  for details.

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,   REF _Ref178152097 \h  \*
MERGEFORMAT  Table 25 .  The LC50 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,   REF _Ref178044350 \h  Table 15 ), the bioavailable (dissolved)
portion sulfometuron methyl would have to be approximately 1500-fold
lower than the highest measured test concentration (~45 ppm) in order
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.

Table   SEQ Table \* ARABIC  25 .  Estuarine/Marine Fish Acute Toxicity
of Sulfometuron Methyl.

Guideline	

Species 	% ai	96-hour

LC50 (mg/L) 	Toxicity Category	MRID No.

Author/Year	Study Classification

72-3	Sheepshead minnow 

(Cyprinodon variegatus)	99.1	> 45	> Slightly

 toxic	416728-03

Ward and Boeri (1990a)	Supplemental(1)

(1) Reclassified as supplemental for the purposes of this risk
assessment.  See   REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H:
Ecological Effects Data Summaries  for additional study details.

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 LC50 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 EC50 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,   REF _Ref178044350 \h  Table 15 ),
the bioavailable (dissolved) portion sulfometuron methyl would have to
be approximately 1300-fold lower than the highest measured test
concentration (~ 40 ppm) in order for risks to be evident.  Therefore,
this study is classified as supplemental but is not recommended for
repeat testing at this time because a repeated test would not likely
affect the risk assessment conclusions.

Table   SEQ Table \* ARABIC  26 .  Freshwater Invertebrate Acute
Toxicity of Sulfometuron Methyl.

Guideline	

Species 	% ai	96-hour

LC50 or 48-h EC50 (mg/L) 	Toxicity Category	MRID No.

Author/Year	Study Classification

72-3	Mysid shrimp(1)

(Mysidopsis bahia)	99.1	> 44.8	> Slightly 

 toxic	416728-04

Ward and Boeri (1990c)	Supplemental (2)

72-3	Eastern oyster(1) 

(Crassostrea virginica)	99.1	> 38.2	> Slightly 

 toxic	416728-05

Ward and Boeri (1990b)	Supplemental(2)

(1) 96-h LC50 applies to mysids; 48-h EC50 applies to oyster.

(2) Reclassified as supplemental for the purposes of this risk
assessment.  See   REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H:
Ecological Effects Data Summaries  for additional study  details.

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;   REF _Ref178404187 \h  \* MERGEFORMAT 
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 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. 

Table   SEQ Table \* ARABIC  27 .  Freshwater Aquatic Invertebrate
Chronic Toxicity for Sulfometuron Methyl. 

 tc "Table IIIC-9.  Freshwater Aquatic Invertebrate Chronic Toxicity for
Flazasulfuron  " \f E  

Species/

Static Renewal	% ai	21-day NOAEC / LOAEC (mg/L)(1)	Endpoints Affected
MRID No.

Author (Year)	Study Classification

Water flea

(Daphnia magna)	99.1	97 / >97	Reproduction	416728-06

Baer (1990)	Acceptable

(1) NOAEC and LOAEC were re-analyzed as part of this risk assessment. 
See Appendix H for additional study details.

Aquatic Animal Sublethal Effects: Formulated Product  and Degradate
Toxicity  tc \l5 "(3).       Sublethal Effects  

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 LC50s (probit
analysis) were reported as follows: 

	

Species	Test Chemical	48-h LC50 (mg/L) 

(95% confidence limits)	Classification	Reference

Diaptomus sp.		

Oust® 

(~93% ai)	1315 (1207-1524)	supplemental	Naqvi and Hawkins (1989)

Eucyclops sp.

1320 (1154-1536)

Alonella sp.

802 (475-928)

Cypria sp

2241 (1744-4517)

This study is classified as supplemental primarily because test
concentrations were not measured in the study and the field 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 LC50
and EC50 values were not achieved for the technical grade herbicide
(e.g., EC50 and LC50 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 LC50 was > 5,000 mg
ai/L for sulfometuron methyl and mortality did not exceed 50% in any
test treatment.  However, review of this study indicates that it is
unacceptable because dissolved oxygen levels dropped precipitously
throughout the study in test concentrations where mortality was
observed, despite periodic aeration of test solutions.  Dissolved oxygen
levels repeatedly reached levels as low as 2.1 mg/L or approximately 25%
saturation, which is well below ASTM recommendations of 60% saturation. 
Because the effect of dissolved oxygen on crayfish mortality could not
be separated from the possible effects of sulfometuron methyl, this
study is not 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 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 “  REF
_Ref179621877 \h  APPENDIX J: Ecological Effects Studies Rejected by OPP
.”

 Field Studies tc \l5 "(4).       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 (  REF
_Ref178154109 \h  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 EC50 (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 EC50 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 EC50 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 (  REF _Ref178154109 \h  \* MERGEFORMAT  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.

 tc \l4 "b.     Aquatic Plants 

Table   SEQ Table \* ARABIC  28 .  Non-target Aquatic Plant Toxicity for
Sulfometuron Methyl.

Species	% ai	EC50/ NOAEC

(µg/L)	Endpoints Affected	MRID No.

Author (Year)	Study Classification

Vascular Species: Duckweed

Duckweed

(Lemna gibba)	95.7	0.48 / 0.21	Frond Count	435385-03

Kannuck (1995)	Acceptable

Non-Vascular Species: Algae and Diatoms

Green Algae (1)

(Selenastrum capricornutum)	99.1	4.6 / 0.63	Cell Density	416801-02

Hobert (1990)	Acceptable

Blue-green Algae(1)

(A. flos-aquae)	99.2	41.6 / <14	Cell Density	435385-02

Thompson (1994)	Supplemental

Fresh Water Diatom (2)

(Navicula pelliculosa)	99.2	>370	Cell Density	435385-02

Thompson (1994)	Acceptable

Salt Water Diatom(2)

(Skeletonema costatum)	99.2	>410	Cell Density	435385-02

Thompson (1994)	Acceptable

(1) Tier II definitive test

(2) Tier I screening  test

Terrestrial Effects Characterization tc \l3 "2.     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 LD50
>4,650 mg ai/kg-bw (  REF _Ref178155491 \h  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.
 

Table   SEQ Table \* ARABIC  29 .  Avian Acute Oral Toxicity for
Sulfometuron Methyl.

Species	% ai	LD50

(mg ai/kg-bw)	Toxicity Category	Accession No.

Author (Year)	Study

Classification

Mallard duck

(Anas platyrhynchos)	>93	>4,650	Practically

non-toxic	245375

Dudeck and Bristol (1981)	Acceptable

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
LC50 values for bobwhite quail and mallard are > 5,620 mg ai/kg-diet and
> 4,600 mg ai/kg-diet, respectively (  REF _Ref178155558 \h  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. 

Table   SEQ Table \* ARABIC  30 .  Avian Subacute Dietary Studies for
Sulfometuron Methyl.

Species	% ai	8-Day LC50

(mg ai/kg-diet)	Toxicity Category	MRID No.

Author (Year)	Study Classification

Northern bobwhite quail

(Colinus virginianus)	95.2	>5,620	Practically

non-toxic	246409 (1)

Beavers and Fink (1981)	Acceptable

Mallard duck

(Anas platyrhynchos)	92	>4,600	Practically

non-toxic	71414

Hazelton Laboratories Inc (1980)	Acceptable

(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;   REF _Ref178155676 \h 
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 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 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.

Table   SEQ Table \* ARABIC  31 .  Mammalian Acute Toxicity for
Sulfometuron Methyl.

Species	% ai	Toxicity	Affected Endpoints	MRID No.

Author (Year)	Toxicity Category

Rat

(Sprague-Dawley)	~100	LD50 > 5,000 mg ai/kg bw  (males/females)
Survival, weight gain, gross organ pathology	43089201

Dashiell and Sarver (1990)	IV

Acute Effects on Terrestrial-phase Amphibians, Reptiles and Beneficial
Insects

exposed at 5 treatments ranging from 13 to 100 μg ai/bee and included a
solvent and negative control (MRID 416728-10;   REF _Ref178155745 \h 
Table 32 ).  Results indicate that sulfometuron methyl is practically
non-toxic to bees on an acute contact basis.  The contact 48-h LD50 for
sulfometuron methyl is >100 µg ai/bee.  Cumulative mortality and
immobility ranged from 4-8% in the controls to 0-2% in the treatments. 
No overt signs of toxicity were observed in the study.  The guideline
(141-1) is fulfilled (MRID 416728-10).

Table   SEQ Table \* ARABIC  32 .  Non-Target Insects - Acute Contact
Toxicity for Sulfometuron Methyl.

Species	% ai	LD50

(µg ai/bee)	Toxicity Category	MRID No.

Author (Year)	Study Classification

Honey Bee

(Apis mellifera)	~100	>100 (contact)	Practically

non-toxic	

416728-10

Hoxter and Smith (1990)	Acceptable

No acceptable or supplemental terrestrial-phase amphibian or reptile
toxicity studies were submitted or located in the open literature based
on a search of the ECOTOX database.

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 (  REF _Ref178566541 \h  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.

Table   SEQ Table \* ARABIC  33 .  Mammalian Developmental Toxicity of
Sulfometuron Methyl .

Species

	% ai	Test

Type	Toxicity1	Affected Endpoints	Accession  No.

Author (year) 

Rabbit

(New Zealand White)	100	Developmental	NOAEL = 300 mg ai/kg/day (highest
test dose)

LOAEL > 300 mg ai/kg/day 	None	78798

Serota (1981)

Terrestrial Animal Sublethal Effects, Formulated Product and Degradation
Products  tc \l5 "(3).      Sublethal Effects 

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;   REF
_Ref178495898 \h  Table 34 ).  Results from this study indicate that the
formulated product DPX-T5486-87 is practically nontoxic to laboratory
rats, with a 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.

Table   SEQ Table \* ARABIC  34 .  Mammalian Acute Toxicity to
Sulfometuron Methyl in Formulated Product: DPX-T5486-87

Species	% ai	Toxicity	Affected Endpoints	MRID No.	Toxicity Category

Rat

(Sprague-Dawley)	74%	LD50 > 5,000 mg ai/kg bw  (males/females)	Survival,
weight gain, gross organ pathology	44874103	IV

Except for saccharin, no toxicity information was available on the other
major degradation products of sulfometuron methyl (e.g., pyrimidine
amine, pyrimidine-ol, sulfonamide).  Data on the toxicity of saccharin
that met ECOTOX and OPP screening criteria were available for nine
studies (Appendix J).  However, further review of these data 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 “  REF _Ref179621877 \h  APPENDIX J: Ecological Effects
Studies Rejected by OPP .”

Field Studies

 tc \l5 "(4).      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 tc \l4 "b.     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 EC25 and EC05,
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 EC25, the EC05 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 (  REF _Ref178157054 \h  Table 35 ). 
For seedling emergence, the EC25 of 1.9 x 10 -4 lb ai/acre for the most
sensitive monocot (sorghum) is about a factor of 5 greater than the EC25
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 EC25
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 EC25
values indicates that species sensitivity is within a factor of 20
(based on summary data presented by McKelvey, 1995).  This indicates
that the most sensitive test species is not an outlier in terms of its
relative sensitivity.  The EC05 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 ECx
values, the actual mean response associated with the EC05 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 EC25 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 EC25 values.  Because the NOEC exceeded
the EC25 values for both species, the EC05 is used for risk assessment
with threatened and endangered species.  The EC05 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 EC25 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 an outlier in terms of its relative sensitivity.  A consistent,
declining monotonic exposure-response curve was observed for corn and
soybean in the vegetative vigor test.  

Table   SEQ Table \* ARABIC  35 .  Summary of Most Sensitive Tier II
Terrestrial Non-target Plant Seedling Emergence and Vegetative Vigor
Toxicity Data for Sulfometuron Methyl.

Most Sensitive Species	

EC25

(lb ai/A)	

NOAEC/[EC05]*

(lb ai/A)	Endpoint

Affected	MRID No.

Author/year	Study Classification

Seedling Emergence

Monocots

Sorghum	1.9 x 10 -4 	4.3 x 10 -5   (*)	shoot height 	435385-01

McKelvey (1995)	Acceptable

Dicots

sugar beet	3.2 x 10 -5	2.9 x 10 -5	shoot dry wt

Acceptable

Vegetative Vigor

Monocots	435385-01

McKelvey (1995)

	Corn	3.7 x 10 -5	9.9 x 10 -7  (*)	shoot dry wt

Acceptable

Dicots

Soybean	1.8 x 10 -5	8.4 x 10 -6  (*)	shoot dry wt

Acceptable

* The NOAEC value is above or equal to the EC25 or below the lowest
concentration, therefore, an EC05 is used instead.



RISK CHARACTERIZATION	

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  tc "A.      
  Risk Estimation - Integration of Exposure and Effects Data " \l 2 

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:

Table   SEQ Table \* ARABIC  36 .  Risk Presumptions for Aquatic
Animals.

Risk Presumption	RQ 	LOC

Acute Risk	EEC(1)/LC50 or EC50	0.5

Acute Restricted Use	EEC/LC50  or EC50	0.1

Acute Endangered Species	EEC/LC50  or EC50	0.05

Chronic Risk	EEC/NOAEC	1

(1)  EEC units in (mg/L or µg/L) in water

Table   SEQ Table \* ARABIC  37 .  Risk Presumptions for Terrestrial
Animals.

Risk Presumption	RQ 	LOC

Acute Risk	EEC(1)/LC50 or LD50/sqft(2) or LD50/day(3)	0.5

Acute Restricted Use	EEC/LC50 or LD50/sqft or LD50/day

 (or LD50 < 50 mg/kg)	0.2

Acute Endangered Species	EEC/LC50 or LD50/sqft or LD50/day	0.1

Chronic Risk	EEC/NOAEC	1

Acute Endangered Terrestrial Invertebrate	EEC(4)/LD50 (4)	0.05

(1)   EEC units are in ppm diet

(2)        mg/sqft              			 

LD50 * wt. of bird       

(3) mg of toxicant consumed/day

           LD50 * wt. of bird  

(4) EEC = ppm in small insects; LD50 = ug/g  bw (ppm)

Table   SEQ Table \* ARABIC  38 .  Risk Presumptions for Plants.

Risk Presumption	RQ	LOC

Terrestrial Plants in Terrestrial and Semi-Aquatic Areas:

Non-Endangered Species	EEC(1)/EC25	1

Endangered Species	EEC/EC05 or NOAEC	1

Aquatic Plants:

Non-Endangered Species	EEC(2)/EC50	1

Endangered Species	EEC/EC05 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 

 tc "1.         Non-target Aquatic Animals and Plants " \l 3 

A summary of the toxicity values used to derive risk quotients for
aquatic animals and plants is provided in   REF _Ref178452513 \h  Table
39  below.  

Table   SEQ Table \* ARABIC  39 .  Endpoints Used for Estimating Risks
of Sulfometuron Methyl to Aquatic Animals and Plants.

(1) tc "Table IVA-4.  Summary of Selected Endpoints for Aquatic Toxicity
Studies " \f D  

Organism Group	Toxicity	Units	MRID #

Freshwater fish, LC50 	> 148 	mg ai/L	435018-02

Freshwater invertebrate EC50	> 150	mg ai/L	435018-03

Marine/estuarine fish LC50	> 45	mg ai/L	416728-03

Marine/estuarine invertebrate (mollusk - oyster) EC50	> 38	mg ai/L
416728-04

Chronic freshwater fish NOAEC	Data gap

Chronic freshwater invertebrate NOAEC	97	mg ai/L	416728-06

Aquatic nonvascular plants EC50/NOAEC	4.6 / 0.63	µg ai/L	416801-02

Aquatic vascular plants EC50/NOAEC	0.48 / 0.21	µg ai/L	435385-03

(1) Details for each study are presented in earlier sections of this
document and in   REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H:
Ecological Effects Data Summaries ,

Fish and Aquatic Invertebrates

All available LC50 or EC50 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;   REF _Ref178452513 \h  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 LC50
or EC50 values represent the lower bound of actual (definitive) LC50 or
EC50 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 be determined from the sulfometuron methyl toxicity
database because a definitive LC50 or EC50 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 LC50 = 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 LC50 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   REF _Ref178453261 \r \h  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 EC50 and NOAEC values for vascular and non-vascular
aquatic plants, respectively (  REF _Ref178157491 \h  \* MERGEFORMAT 
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. 

 tc "Table IVA-5.  Summarized Acute Aquatic Plant Risk Quotients for
Turf Uses " \f D  

Table   SEQ Table \* ARABIC  40 .  Summary of Acute Aquatic Plant Risk
Quotients for Rights of Way Uses.

Scenario	Endangered	Non-endangered

	Vascular	Non-vascular	Vascular	Non-vascular

TX Rights of Way (max rate of 0.375 lbs ai/acre x 1 aerial application/
yr) (a,b)	148  (c)	49 (c)	65 (d)	6.7 (d)

(a) Based on a peak EEC of 31 ug/L derived from the TX rights of way
exposure scenario which yielded the highest EECs.  Details on scenarios
and PRZM-EXAMS modeling are provided in Section    REF _Ref178580641 \r
\h  \* MERGEFORMAT  3.2.2.2  and   REF _Ref179348297 \h  \* MERGEFORMAT 
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 (EC50) 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  tc "2.         Non-target Terrestrial
Animals " \l 3 

A summary of the toxicity values used to derive risk quotients for
terrestrial animals is provided in   REF _Ref178157575 \h  \*
MERGEFORMAT  Table 41  below.  

Table   SEQ Table \* ARABIC  41 .  Endpoints Used for Estimating Risks
of Sulfometuron Methyl to Terrestrial Animals.

Organism Group (a)	Toxicity	MRID #

Bird LD50 (oral dose-based, mg ai/kg-bw)	>4,650	245375

Bird LC50  (dietary-based, mg ai/kg-diet)	>4,600	71414

Mammal LD50 (oral dose-based, mg ai/kg-bw)	>5,000	430892-01

Honeybee LD50, µg ai/bee	>100	416728-10

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

(a) Details for each study are presented in earlier sections of this
document and in   REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H:
Ecological Effects Data Summaries .

 (c) Highest dose tested.

(c) Accession number.

Birds, Acute Risks

The acute LC50/LD50s 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”) LC50/LD50 values, a bounding analysis can be conducted to
provide a conservative, upper bound estimate of the RQs (  REF
_Ref178157712 \h  \* MERGEFORMAT  Table 42  and   REF _Ref178157714 \h 
\* MERGEFORMAT  Table 43 ). 

In this bounding analysis, calculated EECs for various food items from
the TREX terrestrial exposure model are compared to dose-base LD50
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 1/25th the lowest adjusted dose-based LD50
(> 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 (  REF _Ref178157714 \h  Table 43 ). 
Specifically, the highest diet-based EEC (90 mg ai/kg-diet for short
grass) is approximately 1/50th the avian subacute dietary LC50 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   REF _Ref178453261 \r \h  4.2 ).

Table   SEQ Table \* ARABIC  42 .  Upper Bound Kenaga, Acute Avian
Dose-Based Risk Quotients (Bounding Analysis Only).

Size Class

(grams)	Adjusted

LD50

(mg ai/kg-bw)	Short Grass(1)

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 LD50 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   REF _Ref178578557 \r \h  \* MERGEFORMAT  3.2
 and “  REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H: Ecological
Effects Data Summaries ” for details on the model inputs, calculations
and output. 

Table   SEQ Table \* ARABIC  43 . Upper Bound Kenaga, Subacute
Dietary-Based Risk Quotients (Bounding Analysis Only).

Dietary-based LC50

(mg ai/kg-diet)	Short Grass(1)

	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   REF
_Ref178578557 \r \h  \* MERGEFORMAT  3.2  and “  REF _Ref178405615 \h 
\* MERGEFORMAT  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 LD50 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”) LD50 value, a
bounding analysis can be conducted to provide a conservative, upper
bound estimate of the acute, mammalian RQ (  REF _Ref178157883 \h  \*
MERGEFORMAT  Table 44 ). 

In this bounding analysis, calculated EECs for various food items from
the TREX terrestrial exposure model are compared to dose-base LD50
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 LD50 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 “  REF
_Ref179708540 \h  APPENDIX F: T-REX Output ” and acute mammalian risks
are further described in the Risk Description (Section 4.2). “

Table   SEQ Table \* ARABIC  44 .   Upper Bound Kenaga, Acute Mammalian
Dose-Based  Risk Quotients (Bounding Analysis Only).

(1)

Size Class

(grams)	Adjusted

LD50	Short Grass(1)

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 LD50 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   REF _Ref178578557 \r \h  \* MERGEFORMAT  3.2
 and “  REF _Ref178405615 \h  \* MERGEFORMAT  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 (  REF _Ref178157965 \h 
Table 45 ) nor the dietary-based risk quotients (  REF _Ref178494277 \h 
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   REF _Ref179708540 \h  APPENDIX F: T-REX Output ).

Table   SEQ Table \* ARABIC  45 .  Upper Bound Kenaga, Chronic Mammalian
Dose-Based Risk Quotients.

Size Class

(grams)	Adjusted NOAEL(1)

(mg ai/kg-bw/d)	EECs and RQs

Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects	Granivore

EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

15	1206.6	85.8	0.07	39.3	0.03	48.3	0.04	5.36	<0.01	1.19	<0.01

35	976.3	59.3	0.06	27.2	0.03	33.4	0.03	3.71	<0.01	0.82	<0.01

1000	422.3	13.8	0.03	6.3	0.01	7.7	0.02	0.86	<0.01	0.19	<0.01

(1) RQs derived for different size classes using unadjusted NOAEL of 
>300 mg ai/kg-bw/d and dose-based EECs (mg ai/kg-bw/d) calculated using
TREX ver. 1.3.1 with a single application at the maximum allowable label
rate (0.375 lb ai/acre/yr).  See Section   REF _Ref178578557 \r \h  \*
MERGEFORMAT  3.2  and “  REF _Ref178405615 \h  \* MERGEFORMAT 
APPENDIX H: Ecological Effects Data Summaries ” for details on the
model inputs, calculations and output. 

Table   SEQ Table \* ARABIC  46 .  Upper Bound Kenaga, Chronic Mammalian
Dietary-Based Risk Quotients

NOAEC (ppm)	EECs and RQs

	Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

10980	90.00	0.01	41.25	<0.01	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   REF
_Ref178494380 \r \h  \* MERGEFORMAT  3.2  and “  REF _Ref178405615 \h 
\* MERGEFORMAT  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 LD50 is <11 µg/bee.  Based on the
acute contact toxicity study to honeybees, the LD50 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 LD50 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 LD50 of >780
μg ai/g.  This LD50 value is then compared to the EEC of 50.6 ug/g for
small insects/broadleaf plants (  REF _Ref177798194 \h  Table 17 ). The
resulting RQ (EEC/LD50) is <0.06, which is at or below the LOC for
endangered terrestrial invertebrates (0.05).  Therefore, the risk of
direct adverse effects to terrestrial invertebrates is considered low;
however, due to the potential risk identified to plants, the potential
for indirect effects to terrestrial invertebrates from sulfometuron
methyl use cannot be discounted.

Additional discussion of potential risks to these taxa is qualitatively
discussed in the Risk Description portion of this document (Section  
REF _Ref178454248 \r \h  4.2 ). 

Non-target Terrestrial Plants 

A summary of the toxicity values used to derive risk quotients for
terrestrial plants is provided in   REF _Ref178454331 \h  Table 47 
below.  

Table   SEQ Table \* ARABIC  47 .  Summary of Selected Endpoints from
Terrestrial Plant Toxicity Studies of Sulfometuron Methyl

Organism Group	Toxicity

(Lbs A.I./Acre)	MRID #

Terrestrial monocots emergence, EC25, lbs ai/acre

EC05 or NOAEC, lbs ai/acre	EC25 = 1.9 x 10-4

EC05 = 4.3 x 10-5	435385-01

Terrestrial dicots emergence, EC25, lbs ai/acre

EC05 or NOAEC, lbs ai/acre	EC25 = 3.2 x 10-5

NOAEC = 2.9 x 10-5	435385-01

Terrestrial monocots vegetative vigor, EC25, lbs ai/acre

EC05 or NOAEC, lbs ai/acre	EC25 = 3.7 x 10-5

EC05 = 8.4 x 10-6	435385-01

Terrestrial dicots vegetative vigor, EC25, lbs ai/acre

EC05 or NOAEC, lbs ai/acre	EC25 = 1.8 x 10-5

EC05 = 9.9 x 10-7	435385-01

a Details for each study are presented in earlier sections of this
document and in “  REF _Ref178405615 \h  \* MERGEFORMAT  APPENDIX H:
Ecological Effects Data Summaries ”.

Non-Endangered and Endangered Plant Risks

  REF _Ref178405382 \h  \* MERGEFORMAT  Table 48   SEQ CHAPTER \h \r 1 
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   REF _Ref178453261 \r \h  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   REF _Ref178405382 \h  Table 48 . 

Table   SEQ Table \* ARABIC  48 .  RQ Values For Plants In Dry And
Semi-Aquatic Areas Exposed To Sulfometuron Methyl Through Runoff And/Or
Spray Drift. 

Plant Type	Application Method	Terrestrial Adjacent Areas	Semi-Aquatic
Adjacent Areas	Spray Drift

Non-endangered Plant RQs a,b,d

Monocot	 ground spray	118	1007	101

Dicot	 ground spray	703	5977	208

Monocot	Aerial	197	1086	507

Dicot	Aerial	1172	6445	1042

Endangered Plant RQs a,c,d

Monocot	ground spray	523	4448	446

Dicot	ground spray	776	6595	3788

Monocot	Aerial	872	4797	2232

Dicot	Aerial	1293	7112	18939

aDetailed calculations for RQs and TerrPlant (ver 1.2.2) input and
output are provided in “  REF _Ref179701993 \h  \* MERGEFORMAT 
APPENDIX D:  Terrplant Spreadsheet .”

b Non-endangered toxicity thresholds (EC25) 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 EC05) 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
  REF _Ref178394370 \h  \* MERGEFORMAT  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 (
 REF _Ref178394075 \h  Table 16 ) while that for surface water was
calculated using PRZM/EXAMS for the scenario yielding the highest EECs (
 REF _Ref178044350 \h  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   REF _Ref179708808
\h  APPENDIX G:  Modeling of Terrestrial plant Exposure from
Contaminated irrigation Water ).  

Based on this screening analysis, results suggest that sulfometuron
methyl levels in irrigation water from ground water sources would not
exceed non-target or endangered species LOCs (i.e, RQs < 1.0).  However,
RQs based on sulfometuron methyl in irrigation water derived from
surface water sources exceed the LOCs for both non-target and endangered
species (3.9 and 71, respectively), thus indicating a potential risk to
plants adjacent to areas irrigated with surface water sources.  

Table   SEQ Table \* ARABIC  49 .  Risk Quotients for Non-target and
Endangered Plants, Resulting From Exposure to Sulfometuron Methyl in
Irrigation Water

Location	Ground water and Surface Water EEC: 1, 2

(lbs ai/A)	Risk Quotients:

Ground water (GW) and Surface Water (SW) Irrigation

Non-target plants3

(EEC/EC25)	Endangered plants3

(EEC/NOAEC)

Semi-aquatic and terrestrial areas adjacent to irrigated fields	Ground
water: 7.5 x 10-7

Surface water: 6.1 x 10-5

	GW:   0.04

SW:    3.9	GW:   0.76

SW:   71

1 Estimated EEC assumes 1 inch of irrigation water is applied to the
target field, 1% drift of irrigated water containing 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   REF
_Ref178400427 \r \h  \* MERGEFORMAT  3.2.2.2 ;   REF _Ref177972956 \h 
\* MERGEFORMAT  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 LC50 and EC50 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 LC50 and EC50 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 (  REF
_Ref178400557 \r \h  \* MERGEFORMAT  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 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 (  REF _Ref178400557 \r
\h  \* MERGEFORMAT  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 90th percentile ACR of 80 across all chemicals, which if
applied to the freshwater fish LC50 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 90th percentile ACR reflects
pesticides with modes of action that differ from sulfometuron methyl and
therefore may not reflect the 90th percentile ACR within the
sulfonylurea class of herbicides.  However, for the purposes of
evaluating uncertainty 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 ( 
REF _Ref184015257 \h  Figure 3 ).  Results indicate that chronic
toxicity of other sulfonylurea herbicides occurs at concentrations two
to three orders of magnitude greater than the chronic EEC of 0.020 mg/L.
 Therefore, based on the use of a conservative “high end” ACR and
comparison with toxicity information for other sulfonylurea herbicides,
the potential for chronic risk to aquatic animals from direct effects of
sulfometuron methyl appears unlikely. 

Figure   SEQ Figure \* ARABIC  3 . Chronic Toxicity of Sulfonylurea
Herbicides to Freshwater Fish

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 ( 
REF _Ref178401495 \h  \* MERGEFORMAT  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).

 

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

Species	Test Chemical	Exposure Duration	Endpoint (Effect)	Effect Level 

(mg ai/L)	Study Classification	Ref.

Xenopus laevis		sulfometuron methyl (99.5% ai)	96-h	LC50 (% mortality)

NOAEC  (% malformations)	> 24.9 

 24.9 (a)	Supplemental	Fort et al. (1999) 

14-d	NOAEC (tail resorption)

LOAEC (tail resporption)	0.995

9.95

30-d	NOAEC (limb deformation)	24.9(a)

(a) Highest tested dose, LOAEL not achieved in study.

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

Aquatic Plants   tc "b.         Aquatic Plants  " \l 4 

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 EC50 and NOAEC are 0.48 and 0.21 μg/L,
respectively) followed by the green algae (EC50 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

			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 > 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;   REF _Ref178044350 \h  \* MERGEFORMAT  Table 15 ) derived from
the exposure scenario yielding the highest exposure concentrations still
exceeds the 14-d EC50 (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   REF _Ref178582210 \r \h  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).  

Aquatic Toxicity of Sulfometuron Methyl Degradates

As discussed earlier in Section   REF _Ref184002208 \r \h  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.    REF
_Ref184002630 \h  Table 51  displays the results of the ECOSAR model
predictions for five major sulfometuron methyl degradates.  

Table   SEQ Table \* ARABIC  51 .  ECOSAR-predicted toxicity values for
major degradates of sulfometuron methyl.

Degradate Name	ECOSAR Class	Organism	Toxicity Endpoint	Toxicity Value
(mg/L)

2-Hydroxy, 4,6-dimethyl pyrimidine	Phenols	Fish	96-h LC50

90-d Chronic Value	49

0.31

Daphnid	48-h LC50

21-d Chronic Value	13

5.3

Green Algae	96-h EC50	257

2-(Aminosulfonyl) benzoic acid	Neutral organic acids	Fish	96-h LC50

30-d Chronic Value	137,000*

12,600

Daphnid	48-h LC50

16-d EC50	128,000*

2,620

Green Algae	96-h EC50	70,676

Saccharin	Thiazolinone (iso-)	Fish	96-h LC50

Chronic Value**	1.9

0.14

Daphnid	48-h LC50

Chronic Value**	1.6

0.057

Green Algae	96-h EC50	0.41

2-(Aminosulfonyl) benzoic acid, methyl ester	Esters	Fish	96-h LC50

Chronic Value**	152

136

Daphnid	48-h LC50	2,350

Green Algae	96-h EC50

Chronic Value**	11.6

8.7

2-Pyrimidinamine, 4,6-dimethyl	Aromatic amines	Fish	96-h LC50

Chronic Value**	214

0.93

Daphnid	48-h LC50

Chronic Value**	1.6

0.042

Green Algae	Chronic Value**	12.9

 * 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 ( 
REF _Ref178044350 \h  \* MERGEFORMAT  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 (  REF _Ref184002630 \h  \* MERGEFORMAT 
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,   REF _Ref177972956 \h  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 (  REF _Ref184002630 \h  \* MERGEFORMAT 
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; (  REF
_Ref184002630 \h  \* MERGEFORMAT  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.

Risk to Terrestrial Animals

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 (LD50 >4,650 mg/kg-bw)
and practically nontoxic to both upland game birds and waterfowl by the
subacute dietary route (LC50 >5,620 mg/kg-diet and > 4,600 mg/kg-diet,
respectively). Since the LD50 and LC50 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   REF _Ref178404082 \r \h  \* MERGEFORMAT  4.1 ;   REF
_Ref178157712 \h  \* MERGEFORMAT  Table 42  and   REF _Ref178157714 \h 
\* MERGEFORMAT  Table 43 ).  This bounding analysis compared size class
adjusted ‘indefinite’ LD50 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’ LC50 and LD50 values (at which no mortality was
observed in the test) represent definitive LC50 and LD50 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;   REF _Ref179612370 \h  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.  

Figure   SEQ Figure \* ARABIC  4 . Chronic Avian Toxicity of
Sulfonylurea Herbicides

Results from   REF _Ref179612370 \h  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 (  REF _Ref177798194 \h  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
LD50 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 LD50 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 (  REF _Ref178157883 \h  \*
MERGEFORMAT  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 (  REF _Ref178157965 \h  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 (LD50 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. 

Risk to Terrestrial Plants

Tier 1 Modeling of Runoff and Spray Drift

Results presented in Section   REF _Ref178405021 \n \h  \* MERGEFORMAT 
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 (  REF _Ref178405382 \h 
\* MERGEFORMAT  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
(  REF _Ref178405382 \h  \* MERGEFORMAT  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   REF _Ref178407275 \r \h  \*
MERGEFORMAT  4.2.4 .   The potential risk to endangered monocots and
dicots will be discussed in greater detail in Section   REF
_Ref178496349 \r \h  4.2.8.2 .

  SEQ CHAPTER \h \r 1 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   REF _Ref178405615 \h  \* MERGEFORMAT  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   REF _Ref178406112
\r \h  \* MERGEFORMAT  4.1.4 ).    The EEC for ground water (0.33 ug/L)
was calculated using the Tier 1 SCIGROW model (  REF _Ref178394075 \h 
\* MERGEFORMAT  Table 16 ) while that for surface water (31 ug/L) was
calculated using PRZM/EXAMS from the scenario yielding the highest EECs
(  REF _Ref178044350 \h  \* MERGEFORMAT  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   REF _Ref178406298 \r \h  \* MERGEFORMAT 
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   REF _Ref178147274 \h  Table 20  and
  REF _Ref178147279 \h  Table 21 ).

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

Distance Down Wind (Feet)	PERCENT OF APPLICATION RATE	eec (1)
non-endangered plants (2)	endangered plants(3)

	Percent	lb ai/A	RQ	RQ

[A] Ground Application (Low Boom)

0	102.0	0.3822	21233	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 Application (High Boom)

0	106.0	0.3956	21978	399596

50	5.00	0.0187	1039	18889

100	2.48	0.0093	517	9394

200	1.20	0.0045	250	4545

500	0.39	0.0015	83	1515

750	0.22	0.0008	44	808

900	0.17	0.0006	33	606

[C] Aerial (Following Many Label Recommendations)

0	50.00	0.1874	10411	189293

50	17.12	0.0642	3567	64848

100	9.79	0.0367	2039	37071

200	4.69	0.0176	978	17778

500	1.92	0.0072	400	7273

750	1.39	0.0052	289	5253

900	1.24	0.0046	256	4646

[D] Aerial (High-End Exposure Scenario)

0	77.35	0.2900	16111	292929

50	38.32	0.1437	7983	145152

100	25.11	0.0941	5228	95051

200	14.07	0.0527	2928	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 
 REF _Ref178494837 \r \h  \* MERGEFORMAT  3.2.3.1 .

(2) Non-endangered plant RQs based on vegetative vigor EC25 for soybean
of 1.8 x 10-5 lb ai/A (MRID 435385-01)

(3)  Endangered plant RQs based on vegetative vigor EC05 for soybean of
9.9 x 10-7 lb ai/A (MRID 435385-01).

Results from the refined spray drift modeling indicate that RQs exceed
the 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  
REF _Ref178147274 \h  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 3 and 10 mph.

Review of Incident Data

An analysis of the ecological incidents associated with a pesticide
application (or misapplication) is an important part of EPA’s
ecological risk assessment because such information can help establish
additional lines of evidence to the risk assessment 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 (“  REF _Ref184019372 \h  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   REF _Ref182204239 \h  \* MERGEFORMAT  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.   SEQ
CHAPTER \h \r 1 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 1016 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, LC50 or EC50 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 Slope	Endangered Species LOC	Estimated Probability of an
Individual Effect at the Endangered Species LOC	Comment

Fish	4.5 (2 – 9)	0.05	1 in 4 x 108

(1 in 2 x 102 to 1 in 2 x 1031)	Data insufficient to allow for probit
slope derivation; therefore, the default slope of 4.5 with lower and
upper bounds of 2 – 9 was used.

Aquatic Invertebrates	4.5 (2 – 9)

	0.05	1 in 4 x 108

(1 in 2 x 102 to 1 in 2 x 1031)

	Birds	4.5 (2 – 9)	0.1	1 in 2.9x 105 (1 in 44 to 

1 in 9 x 1018)

	Mammals	4.5 (2 – 9)

	0.1	1 in 2.9x 105 (1 in 44 to 

1 in 9 x 1018)

	

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.  

Table   SEQ Table \* ARABIC  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 Effects	Basis for Direct Effects Concern	Indirect
Effects	Basis for Indirect Effects Concern

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

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

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

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

Mammals

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

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

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

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

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

(1)  Birds are used as surrogate species for terrestrial-phase
amphibians and reptiles; therefore, potential direct and indirect
effects to endangered avian, terrestrial-phase amphibians and reptilian
species are considered equivalent.

(2) Fish are used as a surrogate for aquatic phase amphibians;
therefore, potential direct and indirect effects to endangered 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.  

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   REF _Ref178494916 \r \h  \* MERGEFORMAT  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

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;   HYPERLINK "http://www.asabe.org"  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 (Kd) 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

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

Sulfometuron methyl

DPX-T5648; DPX-5648; IN-T5648; IN T5648-18

Methyl 2-(4,6-dimethylpyrimidin-2-ylcarbamoylsulfamoyl)benzoate

	

Saccharin

IN-581

1,2-Benzisothiazol-3(2H)-one, 1,1-dioxide

Sulfometuron pyrimidine amine

IN-X0993; IN-X993; PA

4,6-Dimethyl-2-pyrimidinamine

4,6-dimethyl-2-pyrimidinamine

	

Sulfometuron sulfonamide

IN-D5803; SA; methyl phenylsulfonamide

Methyl 2-(aminosulfonyl)benzoate.

2-(Aminosulfonyl)-benzoic acid, methyl ester

Pyrimidine-ol

IN-11859

4,6-Dimethyl-2-pyrimidinol	

Sulfometuron free acid

FA-SM; IN-T6385

2-[[[[(4,6-Dimethyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-benzoic
acid

0Free acid Sulfonamide

FA-Sulfonamide; Free acid; IN-D5119

2-(Aminosulfonyl)benzoic acid

	

APPENDIX B: Environmental Fate Data Requirements

Environmental Fate Data Requirements for Sulfometuron Methyl

Guideline	

Data Requirement	

Test Material	

MRID	

Study Classification	Data Requirement Met? 	More Data Needed? 

[161-1]

	Hydrolysis	

sulfometuron methyl	42715201	Acceptable	Yes	No

[161-2]	Direct photolysis in water

	

sulfometuron methyl	42182401

43174101	Acceptable	Yes	No

[161-3]	Photolysis on soil

	

sulfometuron methyl	41420601	Acceptable	Yes	No

[161-4]	

Photodegradation in Air	NA	NA	not required	NA	NA

[162-1]

	Aerobic soil metabolism

	sulfometuron methyl	42091401	Acceptable	Yes	No

[162-1]

	Aerobic soil metabolism

	sulfometuron methyl	43174102 and 245375	Acceptable	Yes	No

[162-2]	

Anaerobic Soil Metabolism	NA	NA	ref 162-3	Yes	No

[162-3]	Anaerobic aquatic metabolism

	sulfometuron methyl	42091402 and 43188601	Acceptable	Yes	No

[162-3]	Anaerobic aquatic metabolism

	sulfometuron methyl	4413010-20 (143540)	Acceptable	Yes	No

[162-4]	Aerobic aquatic metabolism

	sulfometuron methyl	42091403 and 43174103	Acceptable	Yes	No

[163-1]	Adsorption/

Desorption

	sulfometuron methyl	42789301	Acceptable	Yes	No

[163-1]	Adsorption/

Desorption

	Pyrimidine amine	42789301	Acceptable	Yes	No

[163-1]	Adsorption/

Desorption

	saccharin	42789301	Acceptable	Yes	No

[163-2]	

Laboratory Volatility	NA	NA	not required	NA	NA

[163-3]	

Field Volatility	NA	NA	not required	NA	NA

[164-1]	Terrestrial Field

Dissipation	Sulfometuron methyl	43212101 and 43637101	Acceptable	Yes	No

[164-2]	

Aquatic Field Dissipation	No study	NA

	NA	NA	NA

[164-3]	Forestry Dissipation	Sulfometuron methyl	42091404 and  43174104

	Acceptable	Yes	No

[165-4]	

Accumulation in Fish	Waived	NA	NA	NA	NA

[165-5]	

Accumulation in aquatic non-target organism (crayfish)	Waived	NA	NA	NA
NA

[166-1]	

Ground Water- small

scale prospective	No Study (not required)	NA	NA	NA	NA

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	Peak	96 hr	21 Day	60 Day	90 Day	Yearly	30-Year

09-10	49.472	47.733	43.139	33.437	27.192	7.450	4.065

12-05	36.060	34.879	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 Metabolism	kbacs	76	days	Half-life	 	 

Aerobic Soil Metabolism	asm	61	days	Half-life	 	 

Hydrolysis:	pH 5	8.8	days	Half-life	 	 

Hydrolysis:	pH 7	139	days	Half-life	 	 

Hydrolysis:	pH 9	224	days	Half-life	 	 

Method:	CAM	2	integer	See PRZM manual	 

Incorporation Depth:	DEPI	4	cm	 	 	 

Application Rate:	TAPP	0.42	kg/ha	 	 	 

Application Efficiency:	APPEFF	0.95	fraction	 	 	 

Spray Drift	DRFT	0.05	fraction of application rate applied to pond

Application Date	Date	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	Peak	96 hr	21 Day	60 Day	90 Day	Yearly	30-Year

09-10	39.996	38.810	34.507	27.791	21.603	6.172	2.769

30-08	27.463	26.544	22.992	16.878	13.881	3.981	1.858

10-08	26.457	25.737	21.998	15.903	12.933	4.017	1.582

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 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 Metabolism	kbacs	76	days	Half-life	 

Aerobic Soil Metabolism	asm	61	days	Half-life	 

Hydrolysis:	pH 5	8.8	days	Half-life	 

Hydrolysis:	pH 7	139	days	Half-life	 

Hydrolysis:	pH 9	224	days	Half-life	 

Method:	CAM	2	integer	See PRZM manual

Incorporation Depth:	DEPI	4	cm	 	 

Application Rate:	TAPP	0.42	kg/ha	 	 

Application Efficiency:	APPEFF	0.95	fraction	 	 

Spray Drift	DRFT	0.05	fraction of application rate applied to pond

Application Date	Date	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. Run	IR	EPA Pond	 	 	 

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

Single PRZM-EXAMS runs for different sites: Sample EEC Summary tables
and sample input files

Florida Citrus scenario

Sorted results

Prob.	Peak	96 hr	21 Day	60 Day	90 Day	Yearly

0.0323	1.642	1.592	1.403	1.072	1.000	0.340

0.0645	1.490	1.446	1.300	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 yearly averages:	0.20175

Output File: Sfmt_FLcitrus1	 	 	 	 	 

Metfile:	w12844.dvf	 	 	 	 

PRZM scenario:	FLcitrusSTD.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	244	mg/L	 	 	 

Kd	Kd	 	mg/L	 	 	 

Koc	Koc	47.5	mg/L	 	 	 

Photolysis half-life	kdp	0	days	Half-life	 	 

Aerobic Aquatic Metabolism	kbacw	292	days	Half-life	 	 

Anaerobic Aquatic Metabolism	kbacs	76	days	Half-life	 	 

Aerobic Soil Metabolism	asm	61	days	Half-life	 	 

Hydrolysis:	pH 5	8.8	days	Half-life	 	 

Hydrolysis:	pH 7	139	days	Half-life	 	 

Hydrolysis:	pH 9	224	days	Half-life	 	 

Method:	CAM	2	integer	See PRZM manual	 

Incorporation Depth:	DEPI	4	cm	 	 	 

Application Rate:	TAPP	0.42	kg/ha	 	 	 

Application Efficiency:	APPEFF	0.95	fraction	 	 	 

Spray Drift	DRFT	0.05	fraction of application rate applied to pond

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

Record 17:	FILTRA	 	 	 	 	 

 	IPSCND	1	 	 	 	 

 	UPTKF	 	 	 	 	 

Record 18:	PLVKRT	 	 	 	 	 

 	PLDKRT	 	 	 	 	 

 	FEXTRC	0.5	 	 	 	 

Flag for Index Res. Run	IR	EPA Pond	 	 	 

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

Florida Turf Scenario

Sorted results

Prob.	Peak	96 hr	21 Day	60 Day	90 Day	Yearly

0.032	0.707	0.686	0.604	0.457	0.372	0.128

0.065	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 yearly averages:	0.046883

Inputs generated by pe5.pl - November 2006

	Data used for this run:	 	 	 	 	 

Output File: Sfmt_FLturf2

 	 	 	 

Metfile:	w12834.dvf	 	 	 	 

PRZM scenario:	FLturfSTD.txt	 	 	 	 

EXAMS environment file:	pond298.exv	 	 	 	 

Chemical Name:	Sulfometuron Methyl	 	 	 	 

Description	Variable Name	Value	Units	Comments	 

Molecular weight	mwt	364.38	g/mol	 	 	 

Henry's Law Const.	henry

atm-m^3/mol	 	 

Vapor Pressure	vapr	5.40E-16	Torr	 	 	 

Solubility	sol	244	mg/L	 	 	 

Kd	Kd

mg/L	 	 	 

Koc	Koc	47.5	mg/L	 	 	 

Photolysis half-life	kdp	0	Days	Half-life	 	 

Aerobic Aquatic Metabolism	kbacw	292	Days	Half-life	 	 

Anaerobic Aquatic Metabolism	kbacs	109	Days	Half-life	 	 

Aerobic Soil Metabolism	asm	61	Days	Half-life	 	 

Hydrolysis:	pH 5	8.8	Days	Half-life	 	 

Hydrolysis:	pH 7	139	Days	Half-life	 	 

Hydrolysis:	pH 9	224	Days	Half-life	 	 

Method:	CAM	1	integer	See PRZM manual	 

Incorporation Depth:	DEPI	0	Cm	 	 	 

Application Rate:	TAPP	0.42	kg/ha	 	 	 

Application Efficiency:	APPEFF	0.99	fraction	 	 	 

Spray Drift	DRFT	0.01	fraction of application rate applied to pond

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

Record 17:	FILTRA

 	 	 	 

	IPSCND	1	 	 	 	 

	UPTKF

 	 	 	 

Record 18:	PLVKRT

 	 	 	 

	PLDKRT

 	 	 	 

	FEXTRC	0.5	 	 	 	 

Flag for Index Res. Run	IR	EPA Pond	 	 	 	 

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

Inputs generated by pe5.pl - November 2006

Data used for this run:	 	 	 	 	 	 

Output File: Sfmt_FLturf1	 	 	 	 	 	 

Metfile:	w12834.dvf	 	 	 	 	 

PRZM scenario:	FLturfSTD.txt	 	 	 	 	 

EXAMS environment file:	pond298.exv	 	 	 	 	 

Chemical Name:	Sulfometuron Methyl	 	 	 	 

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 Metabolism	kbacs	76	Days	Half-life	 	 

Aerobic Soil Metabolism	asm	61	Days	Half-life	 	 

Hydrolysis:	pH 5	8.8	Days	Half-life	 	 

Hydrolysis:	pH 7	139	Days	Half-life	 	 

Hydrolysis:	pH 9	224	Days	Half-life	 	 

Method:	CAM	2	integer	See PRZM manual	 

Incorporation Depth:	DEPI	4	cm	 	 	 

Application Rate:	TAPP	0.42	kg/ha	 	 	 

Application Efficiency:	APPEFF	0.95	fraction	 	 	 

Spray Drift	DRFT	0.05	fraction of application rate applied to pond

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

Record 17:	FILTRA	 	 	 	 	 

 	IPSCND	1	 	 	 	 

 	UPTKF	 	 	 	 	 

Record 18:	PLVKRT	 	 	 	 	 

 	PLDKRT	 	 	 	 	 

 	FEXTRC	0.5	 	 	 	 

Flag for Index Res. Run	IR	EPA Pond	 	 	 	 

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

APPENDIX D:  Terrplant 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 (ppm)	244 (pH 7)

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 areas

(A/I)*R*10	0.1875

Spray drift

A*D	0.00375

Total for dry areas

((A/I)*R)+(A*D)	0.0225

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

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

 	Seedling Emergence	Vegetative Vigor

Plant type	EC25	NOAEC 	EC25	NOAEC 

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 Magnitude	Appl. Rate	Appl. Method	Affected Species	Product

I011666-001	Municpal operation	01-Nov-00	Registered use	Highly Probable
ID

2000	Thousands Of Acres	1 Oz/Acre	Aerial	1	OUST

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

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

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 (accidental)	Probable	MS

1997	Unknown

RUN-OFF	1

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

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

I006010-001	Right-of-way, road	20-Aug-97	Misuse (accidental)	Probable	LA

1997	Unknown	N/R	N/R	1

	I000903-003	Agricultural Area	01-Jan-94	Registered use	Probable	TX

1994	N/R	N/R	Spray	2,3,4	OUST

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

I006010-002	Agricultural area	20-Aug-97	Misuse (accidental)	Probable	TX

1997	Unknown	N/R	N/R	1

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

I007269-002	YARD	29-May-98	Registered use	Probable	TN	Davidson	1998	All
N/R	N/R	1	OUST

I015217-001	Forest	21-May-04	Registered use	Probable	OH	Gallia	2004	8000
Sq Ft	3 Oz/Acre	Spray	1	Oust herbicide

I015832-001	Right-of-way, road	14-Dec-04	Registered use	Probable	LA
Lafayette	2004

N/R	Spray	1	Oust

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

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

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

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

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

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

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

	1

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

Spray	1	Oust

I015796-001	Right-of-way, utility	08-Nov-04	Registered use	Possible	KY
Jessamine	2004	1-4 Acres	3 Oz/Acre	Nr	1	Oust XP Herbicide

B000601-011	N/R	16-May-88	Registered use	Possible	CA	Kern	1988	N/R

	1	Oust

I000071-001	Peach	01-Jan-92	Registered use	Possible	SC	Saluda	1992
Numerous Trees	N/R	N/R	1	OUST

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

Spray	1	Oust

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

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

Spray	1

	I009556-005	Agricultural area

Misuse (accidental)	Possible	NC

0	Unknown	N/R	N/R	1	OUST

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

NR	NR	1	Oust

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

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

Spray	1	Oust

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

1	Oust

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

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

APPENDIX F: T-REX Output

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

TREX MODEL INPUTS	 	 

 

 

 

 

 

Chemical Name:	Sulfometuron methyl

	      Use:	non-crop; forest, rights-of-way

	Product name and form:	Oust (et al): water dispersible graunule

	% A.I. (leading zero must be entered for formulations <1% a.i.):
100.00%

	Application Rate (lbs/A): 	0.375	 

	Half-life (days):	35	 

	Application Interval (days):	 	 

	Number of Applications:	1	 

	Note: Sources of wildlife diet are assumed to be available for less
than one year for this model.	 	 

	Endpoints	 

	 Avian 	Indicate test species below

 	LD50 (mg/kg-bw)	4650.00	2 (mallard)

 	LC50 (mg/kg-diet)	4600.00	2 (mallard)

 	NOAEL (mg/kg-bw)	 	2

 	NOAEC (mg/kg-diet)	 	1

 	Enter the Mineau et al. Scaling Factor	1.15

 Mammals

 

 	LD50 (mg/kg-bw)	5000.00	 Rat

 	LC50 (mg/kg-diet)	 	 

 

Reported Chronic Endpoint (mg/kg-bw/d)	549.00	Scaled to 350 g from
Rabbit Developmental Tox Study

 

Is dietary concentration (mg/kg-diet) reported from the available
chronic mammal study? (yes or no)	no	 

 

Enter dietary concentration (mg/kg-diet)	 	 

 

Estimated Chronic Diet Concentration Equivalent to Reported Chronic
Daily Dose	10980	mg/kg-diet based on standard FDA lab rat conversion



Table F-2. T-REX Output: Upper Bound Kenaga, Acute Avian Dose-Based Risk
Quotients

Size Class

(grams)	

Adjusted

LD50	EECs and RQs

Short Grass	Tall Grass

Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

20	2414.40	102.50	0.04	46.98	0.02	57.66	0.02	6.41	0.00

100	3073.65	58.45	0.02	26.79	0.01	32.88	0.01	3.65	0.00

1000	4341.65	26.17	0.01	11.99	0.00	14.72	0.00	1.64	0.00

 

Table F-3.  T-REX Output: Upper Bound Kenaga, Subacute Avian Dietary
Based Risk Quotients

LC50	EECs and RQs

	Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

4600	90.00	0.02	41.25	0.01	50.63	0.01	5.63	0.00

Size class not used for dietary risk quotients 

Table F-4. T-REX Output: Upper Bound Kenaga, Acute  Mammalian Dose-Based
 Risk Quotients 

Size Class

(grams)	

Adjusted

LD50	EECs and RQs

Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects	Granivore

EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

15	10989.15	85.81	0.01	39.33	0.00	48.27	0.00	5.36	0.00	1.19	0.00

35	8891.40	59.30	0.01	27.18	0.00	33.36	0.00	3.71	0.00	0.82	0.00

1000	3845.80	13.75	0.00	6.30	0.00	7.73	0.00	0.86	0.00	0.19	0.00

Table F-5.  T-REX Output: Upper Bound Kenaga, Chronic Mammalian Dietary
Based Risk Quotients

NOAEC (ppm)	EECs and RQs

	Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

10980	90.00	0.01	41.25	0.00	50.63	0.00	5.63	0.00

Size class not used for dietary risk quotients 

Table F-6: T-REX Output:  Upper Bound Kenaga, Chronic Mammalian
Dose-Based Risk Quotients

Size Class

(grams)	Adjusted NOAEL	EECs and RQs

Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects	Granivore

EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

15	1206.61	85.81	0.07	39.33	0.03	48.27	0.04	5.36	0.00	1.19	0.00

35	976.28	59.30	0.06	27.18	0.03	33.36	0.03	3.71	0.00	0.82	0.00

1000	422.27	13.75	0.03	6.30	0.01	7.73	0.02	0.86	0.00	0.19	0.00

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) = 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/EC25 for vegetative vigor =    
7.03 x 10-5 lbs ai/A = 3.9

					 				       1.8 x 10-5 lbs ai/A 

 

Endangered Plant RQ:

From 1 acre-inch of surface water: EEC/EC05 for vegetative vigor =  

							7.03 x 10-5 lbs ai/A = 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) = 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/EC25 for veg.vigor =  7.48 x 10-5
lb ai/A = 0.04

								    1.8 x 10-5 lbs ai/A

Endangered Plant RQ:

From 1 acre-inch of ground water: EEC/EC25 for veg.vigor =  7.48 x 10-5
lb ai/A = 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 LC50 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 than
the highest measured test concentration (~45 ppm) in order for risks to
be evident.  Therefore, this study is classified as supplemental but is
not recommended for repeat testing at this time because a repeat test
would be highly unlikely to alter the risk assessment conclusions.

Estuarine and Marine Invertebrates, Acute

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 LC50 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 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 EC50 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 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.

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 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 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 EC50 (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.

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 EC50 (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 EC50 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

			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 > 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 (> 93% ai) is practically
non-toxic on an acute basis (MRID 245375).  An oral LD50 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 LC50 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. 

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

eturon 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 LD50 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 tc \l4 "b.     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 EC25 and EC05,
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 EC25, the EC05 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 EC25 of
1.9 x 10 -4 lb ai/acre for the most sensitive monocot (sorghum) is about
a factor of 5 greater than the EC25 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 EC25 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 ‘outliers’ in terms of their relative sensitivity.  The EC05
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 ECx values, the actual mean response
associated with the EC05 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 EC25 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 EC25 values for both species, the EC05 is
used for risk assessment with threatened and endangered species.  The
EC05 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 EC25 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 ‘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: 

	

Species	Test Chemical	48-h LC50 (mg/L) 

(95% confidence limits)	Classification	Reference

Diaptomus sp.		

Oust® 

(~93% ai)	1315 (1207-1524)	supplemental	Naqvi and Hawkins (1989)

Eucyclops sp.

1320 (1154-1536)

Alonella sp.

802 (475-928)

Cypria sp

2241 (1744-4517)

This study is classified as supplemental primarily because test
concentrations were not measured in the study and the field 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 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).

 

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

Species	Test Chemical	Exposure Duration	Endpoint (Effect)	Effect Level 

(mg ai/L)	Study Classification	Ref.

Xenopus laevis		sulfometuron methyl (99.5% ai)	96-h	LC50 (% mortality)

NOAEC  (% malformations)	> 24.9 

 24.9 (a)	Supplemental	Fort et al. (1999) 

14-d	NOAEC (tail resorption)

LOAEC (tail resporption)	0.995

9.95

30-d	NOAEC (limb deformation)	24.9(a)

(a) Highest tested dose, LOAEL not achieved in study.

Terrestrial Organisms

Busse et al. (2005). In a greenhouse study, Busse et al. (2005) studied
the effect of sulfometuron methyl (applied as the formulated product
Oust) on ectomycorrhizal formation and seedling growth of three conifer
species: ponderosa pine (Pinus ponderosa), Douglas fir (Pseudosuga
menziesii), and white fir (Abies concolor).  Conifer seedlings (5
replicates) were grown 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

Ecological Effects Data Requirements for Sulfometuron Methyl

Guideline	

Data Requirement	

Test Material	

MRID	

Study Classification	Data Requirement Met? 	More Data Needed? 

71-1	

Avian Oral LD50	

sulfometuron methyl	245375	Acceptable	Yes	No

71-2	

Avian Dietary LC50	

sulfometuron methyl	71414

246409 (2)	Acceptable  Acceptable	Yes	No

71-4	

Avian Reproduction	

sulfometuron methyl

Data Gap	No	Reserved(3) 

72-1	

Freshwater Fish LC50	sulfometuron methyl	435018-01

435018-02	Acceptable	Yes	No

72-2	

Freshwater Invertebrate Acute LC50	sulfometuron methyl	435018-03
Acceptable (1)	Yes	No

72-3(a)	

Estuarine/Marine Fish LC50	sulfometuron methyl	416728-03	Supplemental
(1)	No	Reserved(3)

72-3(b)	

Estuarine/Marine Mollusk EC50	sulfometuron methyl	416728-05	Supplemental
(1)	No	Reserved(3) 

72-3(c)	

Estuarine/Marine Shrimp EC50	sulfometuron methyl	416728-04	Supplemental
(1)	No 	Reserved(3) 

72-4(a)	

Freshwater Fish Early Life-Stage	sulfometuron methyl	423857-04; 249796
(2)	Invalid (1)	No	Reserved(3)

72-4(b)	

Aquatic Invertebrate Life-Cycle (freshwater)	sulfometuron methyl
416728-06	Acceptable	Yes	No

123-1(a)	Seedling Emergence

(Tier II)	sulfometuron methyl	435385-01	Acceptable	Yes	No

123-1(b)	

Vegetative Vigor (Tier II)	sulfometuron methyl	435385-01	Acceptable	Yes
No

123-2

Aquatic Plant Growth	

Blue-green Algae (Tier II)	sulfometuron methyl	435385-02	Acceptable	Yes
No

	Duckweed, Lemna gibba 

(Tier II)	sulfometuron methyl	435385-03	Acceptable	Yes	No

	

Freshwater Diatom, Navicula (Tier 1)	sulfometuron methyl	435385-02
Acceptable	Yes	No

	

Marine Diatom  (Tier 1)	sulfometuron methyl	435385-02	Acceptable	Yes	No

	

Green algae (Tier II)	sulfometuron methyl	416801-02	Acceptable	Yes	No

141-1	

Honey Bee Acute

Contact LD50	sulfometuron methyl	416728-10	Acceptable	Yes	No

(1) Study was re-classified as part of this risk assessment.

(2) Accession number.

(3) Data requirement not met for this guideline study.  However, risk
assessment results are not likely to 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:  Target/efficacy study, Mixtures;
EcoReference No.: 31608)

	Anderson, R. L., Lefever, F. R., and Maurer, J. K. (1988). The Effect
of Various Saccharin Forms on Gastro-Intestinal Tract, Urine and Bladder
of Male Rats.  Food Chem.Toxicol. 26: 665-669. (Rejection Rationale: 
Endpoint Relevancy; EcoReference No.: 82947)

	Byl, T. D. and Klaine, S. J. (1991). Peroxidase Activity as an
Indicator of Sublethal Stress in the Aquatic Plant Hydrilla verticillata
(Royle).  In: J.W.Gorsuch, W.R.Lower, W.Wang, and M.A.Lewis (Eds.),
Plants for Toxicity Assessment, 2nd Volume, ASTM STP 1115, Philadelphia,
PA 101-106. (Rejection Rationale:  Superceded by Byl et al, 1994; 
EcoReference No.: 17181)

	Cumberland, P. F. T., Richold, M., Parsons, J. F., and Pratten, M. K.
(1994). Further Evaluation of a Teratogenicity Screen Using an
Intravitelline Injection Technique.  Toxicol. In Vitro 8: 153-166.
(Rejection Rationale:  Endpoint Relevancy, Exposure 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)Benzoa
te Or Dpx 5648, A New Herbicide for Weeding Uncultivated Plac.  Columa
3: 257-265. (Rejection Rationale:  Target/Efficacy study; EcoReference
No.: 31204)

	Epelbaum, S., Landstein, D., Arad, S., Barak, Z., Chipman, D. M.,
Larossa, R. A., and Vandyk, T. K. (1992). Is the Inhibitory Effect of
the Herbicide Sulfometuron Methyl due to 2 Ketobutyrate Accumulation? 
In: B.K.Singh, H.E.Flores, and J.C.Shannon (Eds.), 7th Annu. Penn. State
Symp. in Plant Physiol., May 28-30, Univ.Park, PA, Am.Soc.of Plant
Physiol., Rockville, MD 352-353. (Rejection Rationale:  Target/Efficacy
study, Toxicity mechanisms);

	Fleischer, S. J., Gaylor, M. J., Dickens, R., and Turner, D. L. (1989).
Roadside Management of Annual Fleabane (Erigeron annuus) and Wild Carrot
(Daucus carota).  Weed Technol. 3: 72-75. (Rejection Rationale: 
Target/Efficacy study; EcoReference No.: 90965) EcoReference No.: 49268)

	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: 
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:  Endpoint relevancy;
EcoReference No.: 82213)

	Kim, H.-C., Cha, S.-W., Ha, C.-S., Roh, J.-K., Lee, Y.-S., Furukawa,
F., Nishikawa, A., and Takahashi, M. (1996). Reappraisal of Eight
Representative Carcinogenic and Non-Carcinogenic Compounds in a New
Medium-Term Rat Liver Bioassay Using.  Cancer Lett. 104: 85-90.
(Rejection Rationale:  Endpoint relevancy; EcoReference No.: 90556)

	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:  Target/Efficacy study, Mixture;
EcoReference No.: 31373)

	Kitchin, K. T. and Ebron, M. T. (1983). Studies of Saccharin and
Cyclohexylamine in a Coupled Microsomal activating/Embryo Culture
System.  Food Chem.Toxicol. 21: 537-541. (Rejection Rationale:  Endpoint
relevancy; EcoReference No.: 90513)

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

	Liscia, A., Masala, C., Crnjar, R., Sollai, G., and Solari, P. (2004).
Saccharin Stimulates the "Deterrent" Cell in the Blowfly:  Behavioral
and Electrophysiological Evidence.  Physiol.Behav. 80: 637-646.
(Rejection Rationale:  Endpoint relevancy; EcoReference No.: 90053)

	Nascimento, M. G., De Oliveira, M. L. C. S., Lima, A. S., and De
Camargo, J. L. V. (2006). Effects of Diuron
[3-(3,4-Dichlorophenyl)-1,1-Dimethylurea] on the Urinary Bladder of Male
Wistar Rats .  Toxicology 224: 66-73. (Rejection Rationale:  Endpoint
relevancy; EcoReference No.: 90555)

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

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

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:  T;  Effect Codes: 
REP,GRO,BEH; Rejection Code:  NO ENDPOINT(SAC)//PCBRES
CODED,RQA,DATA,ENTERED,DONE.

	2. 	Asamoto, M., Mann, A. M., and Cohen, S. M. (1994). P53 Mutation is
Infrequent and Might not give a Growth Advantage in Rat Bladder
Carcinogenesis In Vivo.  Carcinogenesis 15: 455-458.

EcoReference No.: 90517

Chemical of Concern: SAC;  Habitat:  T;  Effect Codes:  CEL; Rejection
Code:  NO MIXTURE(SAC),NO COC(SMM).

	3. 	Bannasch, P., Griesemer, R. A., Anders, F., Becker, R., Cabral, J.
R., Della Porta, G., Feron, V. J., Henschler, D., Ito, N., Kroes, R.,
Magee, P. N., McKnight, B., Montesano, R., Napalkov, N. P., Nesnow, S.,
Roberfroid, M., Slaga, T., Turusov, V. S., Wilbourn, J., and Williams,
G. M. (1986). 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:  T;  Effect Codes: 
MOR,PHY; Rejection Code:  NO CONTROL,ENDPOINT(SAC).

	4. 	Bantle, J. A., Burton, D. T., Dawson, D. A., Dumont, J. N., Finch,
R. A., Fort, D. J., Linder, G., and Rayburn, J. R. (1994). Fetax
Interlaboratory Validation Study:  Phase II Testing. 
Environ.Toxicol.Chem. 13: 1629-1637.

EcoReference No.: 13502

Chemical of Concern: SMM;  Habitat:  A;  Rejection Code:  NO
CONTROL(SMM).

	5. 	Boswell, K. J., Reid, M. L., Fitch, J. V., 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:  T;  Effect Codes:  GRO,BEH;
Rejection Code:  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:  A;  Effect Codes:  BCM,GRO;
Rejection Code:  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:  A;  Effect Codes: 
BCM,GRO; Rejection Code:  LITE EVAL CODED(CuS),NO ENDPOINT(SMM).

	8. 	Cumberland, P. F. T., Richold, M., Parsons, J., and Pratten, M. K.
(1994). Intravitelline Injection of Rodent Conceptuses:  An Improved In
Vitro Developmental Toxicity Screen.  Toxicol.In Vitro 8: 731-733.

EcoReference No.: 91267

Chemical of Concern: ETU,SAC;  Habitat:  T;  Effect Codes:  GRO,BCM,CEL;
Rejection Code:  NO CONTROL,NO ENDPOINT(ETU,SAC).

	9. 	Duan, J. J. and Prokopy, R. J. (1993). Toward Developing
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:  T;  Effect Codes:  BEH; Rejection
Code:  NO CONTROL,ENDPOINT(SAC).

	10. 	Fedtke, C., Schmalfuss, J., and Couderchet, M. (1999).
Chloroacetanilides, Oxyacetamides, Tetrazolinones:  Mode of Action.  1. 
Cross Resistance and Oleic Acid Incorporation in Algal Model Systems. 
Pestic.Sci. 55: 580-582 .

EcoReference No.: 90964

Chemical of Concern: SMM,PCP,PAQT,DU,ACR,BTC,ATZ,BSF,CPP,MBZ;  Habitat: 
A;  Effect Codes:  POP; Rejection Code:  NO
CONTROL,ENDPOINT(SMM,PCP,ATZ).

	11. 	Ferguson, S. A., Delclos, K. B., 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:  T;  Effect Codes:  GRO,BEH;
Rejection Code:  NO ENDPOINT(SAC).

	12. 	Ferguson, S. A., Flynn, K. M., Delclos, K. B., and Newbold, R. R.
(2000). Maternal and Offspring Toxicity but few Sexually Dimorphic
Behavioral Alterations Result from Nonylphenol Exposure. 
Neurotoxicol.Teratol. 22: 583-591.

EcoReference No.: 68835

Chemical of Concern: SAC,NYP;  Habitat:  T;  Effect Codes: 
BEH,GRO,MOR,REP; Rejection Code:  NO ENDPOINT(SAC).

	13. 	Flynn, K. M., Ferguson, S. A., Delclos, K. B., and Newbold, R. R.
(2000). Effects of Genistein Exposure on Sexually Dimorphic Behaviors in
Rats.  Toxicol.Sci. 55: 311-319.

EcoReference No.: 90544

Chemical of Concern: SAC;  Habitat:  T;  Effect Codes:  GRO,BEH;
Rejection Code:  NO ENDPOINT(SAC).

	14. 	Gonzalez, F. E., Atkins, R. L., and Brown, G. C. (1984).
Sulfometuron Methyl, Rate and Timing Studies on Bermudagrass and
Bahiagrass Roadside Turf.  Proc.South Weed Sci.Soc. 37: 272-274.

EcoReference No.: 31768

Chemical of Concern: SMM;  Habitat:  T;  Effect Codes:  GRO; Rejection
Code:  NO ENDPOINT,NO CONTROL(TARGET-SMM).

	15. 	Hannan, P. J. (1995). A Novel Detection Scheme for Herbicidal
Residues.  Environ.Toxicol.Chem. 14: 775-780.

EcoReference No.: 69628

Chemical of Concern: ATZ,PPZ,THF,CRME,TNM,AMTR,CZE,SMM;  Habitat:  AT; 
Effect Codes:  PHY; Rejection Code:  NO ENDPOINT(ALL CHEMS) .

	16. 	Hartnett, M. E., Newcomb, J. R., and Hodson, R. C. (1987).
Mutations in Chlamydomonas reinhardtii Conferring Resistance to the
Herbicide Sulfometuron Methyl.  Plant Physiol.(Bethesda) 85: 898-901.

EcoReference No.: 90536

Chemical of Concern: SMM;  Habitat:  A;  Effect Codes:  POP,PHY;
Rejection Code:  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:  A;  Effect Codes:  ACC; Rejection
Code:  NO ENDPOINT(SMM).

	18. 	Hicks, R. M., Wakefield, J. S. J., and Chowaniec, J. (1975).
Evaluation of a New Model to Detect Bladder Carcinogens or
Co-Carcinogens; Results Obtained with Saccharin, Cyclamate and
Cyclophosphamide.  Chem.-Biol.Interact. 11: 225-233.

EcoReference No.: 91040

Chemical of Concern: SAC;  Habitat:  T;  Effect Codes:  PHY; Rejection
Code:  NO ENDPOINT(SAC).

	19. 	Ikeda, M., Mitsui, T., Setani, K., Tamura, M., Kakeyama, M., Sone,
H., Tohyama, C., and Tomita, T. (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:  T;  Effect Codes: 
BEH,REP,GRO,BCM,PHY; Rejection Code:  NO ENDPOINT(SAC)//PCBRES
CODED,RQA,DATA ENTERED,DONE.

	20. 	Ioannides, C., Lum, P. Y., and Parke, D. V. (1984). Cytochrome
P-488 and the Activation of Toxic Chemicals and Carcinogens. 
Xenobiotica 14: 119-137 .

EcoReference No.: 90546

Chemical of Concern: ETHN,SAC,DDT,AND;  Habitat:  T;  Effect Codes: 
CEL,BCM; Rejection Code:  NO ENDPOINT(SAC).

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

EcoReference No.: 5895

Chemical of Concern: Cd,SMM;  Habitat:  A;  Rejection Code:  NO
ENDPOINT(SMM).

	22. 	Koeppe, M. K. and Mucha, C. F.  (1991). Metabolism of Sulfometuron
Methyl in Lactating Goats.   J.Agric.Food Chem. 39: 2304-2309.

EcoReference No.: 90542

Chemical of Concern: SMM;  Habitat:  T;  Effect Codes:  ACC; Rejection
Code:  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:  A;  Effect Codes:  CEL; Rejection
Code:  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:  T;  Effect Codes:  POP,PHY;
Rejection Code:  NO ENDPOINT(ALL CHEMS,TARGET-IZP,SMM,SMU).

	25. 	Landstein, D., Arad, S., Barak, Z., and Chipman, D. M. (1993).
Relationships Among the Herbicide and Functional Sites of Acetohydroxy
Acid Synthase from Chlorella emersonii.  Planta 191: 1-6.

EcoReference No.: 91069

Chemical of Concern: SMM;  Habitat:  A;  Effect Codes:  BCM; Rejection
Code:  NO ENDPOINT(SMM).

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

EcoReference No.: 90966

Chemical of Concern: SMM;  Habitat:  A;  Effect Codes:  BCM,PHY;
Rejection Code:  NO ENDPOINT(TARGET-SMM).

B*

B*

B*

"

#

$

R

o

—

³

Ê

Û

ò

!

"

ò

ó

ô

õ

ᔓ᭨᥊ᘀ婷㔀脈䩃 ᔓ⹨ࠆᘀ婷㔀脈䩃
ᘍ婷㔀脈䩃 ᤀò

ó

ô

I

¶

̤̀␱愀̤m欀Ꝥ

jÌ

jO

'

(

)

C

D

E

F

G

H

I

J

K

g

h

i

j

n

o

”

•

–

°

±

²

³

´

µ

¶

·

!·

¸

Ô

Õ

Ö

×

Û

Ü

j

j

j

B*

 h

h

h

 h

hA

hA

hA

hA

ùòëòëòùòäòùÝùÒùÄÀÒ¼ÒÝ±Ý£À±¼±œù•ò‘Š
‘Š†Š‘Š‘Š‘Š‘Š‘Š‘ h

 h

B*

B*

 h

਀&䘋

␆ਁ&䘋

h

”ÿø

瑹פ:Ԁ

”ÿø

B*

h

hŠz

hÐ

hÐ

hŠz

hH

 hH

hH

gdH

hH

hH

hH

hH

B*

B*

B*

H

&

@

b

…

†

C

D

G

H

I

J

t

´

Â

.H

I

J

u

v

␅؁Ĥ萏и葞и摧ѱí

摧ѱí

$

Æ

Æ

  h

Æ

Æ

Æ

Æ

Æ

Æ

Æ

  h

Æ

	”

Æ

Æ

Æ

  h

Æ

Æ

hŠz

hÝ

gdÝ

ytÝ

gdÝ

ytÝ

ytÝ

gdÝ

ytÝ

gdÝ

ytÝ

gdÝ

ytÝ

gdÝ

ytÝ

gdÝ

gdÝ

gdÝ

a$gdÝ

gdÝ

a$gdÝ

gdÝ

ytÝ

a$gdÝ

gdÝ

ytÝ

a$gdÝ

gdÝ

ytÝ

a$gdÝ

gdÝ

ytÝ

ytÝ

gdÝ

ytÝ

j

葞Ũ葠ﺘ摧ᓞ

葞ฐ葠摧ᓞ

葞ː葠ﺘ摧嬘ú

”ÿô

”ÿô

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

¸	Ì

h

h

¸	Ì

¸	Ì

¸	Ì

 h]

 h]

h]

h

 h]

h]

h]

H*

Ȁ亖̀Ĵ혈Fꘃ髿뀋刓&

a$gd	B

L	”

a$gd	B

L	”

 h]

Ȁ亖̀Ĵ혈Fꘃ髿᠋刕&

¶

{

kd

଀

'

(

º

»

	

	

"

#

(

9

D

E

I

[

g

h

l

t

ˆ

‹

—

™

š

ž

¥

¦

§

Á

Â

Ã

Ä

Å

å

ê

'

؀'

(

)

3

4

8

9

º

܀º

»

¼

Ê

Ë

Ø

Ù

	

瑹擿g܀සහ

Ä

Å

Í

Õ

Ý

å

෥෦

᠀

᠀

᠀

᠀

᠀

æ

è

î

ô

ú

ê

í

î

ó

鐇ư혈r鐅菿䌄̋缒㼛耢᠄

耀쀆᠆

耀쀆᠆

耀簆᠉

耀쀆᠆

ီု

0ၔၕ

᠀

᠀

᠀

᠀

᠀

鐇ư혈r鐅㯿贅ﰞ耤᠀

耀᠀

耀᠀

耀᠀

耀᠀

{

{

z

j

晆ﴁ

	

晆џ

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

Ò

&

&

&

&

&

&

 h

h

h

&

&

&

&

&

&

&

&

&

&

&

&

&

&

 h

h

h

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

$	Ø	@

&

&

&

&

&

$	Ø	@

&

&

&

&

&

&

$	Ø	@

  h3

  h3

 h3

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

&

$	Ø	@

"

&

\

\

&

&

&

&

&

&

&

&

 h

h

h

 h

h

 h

h

h

h

˜

˜

'˜

!

&

0

4

9

Y

b

c

f

Þ

à

â

ã

þ

h

h

 h

h

摧睖u؀

 h

h

 h

h

h

h

hÉ

 hÉ

 hÉ

hÉ

hÉ

C

gdÉ

hÉ

hÉ

hÉ

hÉ

hÉ

hÉ

hÉ

hÉ

hÉ

hÉ

&

&

&

&

	

&

&

&

&

&

&

 h3

  h3

摧Ⰷ

 h3

$

 hÉ

 hÉ

 hÉ

  hÉ

 hÉ

  hÉ

 hÉ

 hÉ

 hÉ

 hÉ

 hÉ

 hÉ

 hÉ

 hÉ

 hÉ

  hÉ

 h§

 hÉ

hà

  hÉ

  hÉ

  hÉ

  hÉ

 hÉ

 hÉ

  hÉ

 hÉ

 hÉ

  hÉ

 hÉ

 h

h

h

 h

h

h

  hÉ

&

$	Ø	@

 hÉ

hÉ

 hÉ

  hÉ

 hÉ

 hÉ

  hÉ

 hÉ

 hÉ

  hÉ

 hÉ

  hÉ

  hÉ

Á

Â

„@

„0ý^„@

À

Â

ጆ

ጆ

ጆ

ጆ

 hG

摧拆Þ

ԀĤ␆ਁ&䘋

਀&䘋

态ú萏ː萑ﴰ葞ː葠ﴰ摧㟷

摧㟷

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

h÷7

gd÷7

gd÷7

h÷7

h÷7

h÷7

h÷7

摧㟷

 hU

kd

ú

ú

ú

ú

ú

ú

'p

kd

kd'

Ó

Ó

Ó

Ó

Ó

Ó

'p

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

瑹䋿+̀

'

B*

B*

瑹䜔Rက

ù	.

ô

ù	.

ô

ù	.

ô

ù	.

ô

 h8:

 h8:

 h8:

 h8:

 h8:

 h8:

_

`

 h§

 hÉ

 hÉ

 hÉ

@

@

@

@

@

@

@

$

@

@

$

@

@

Ff

@

@

܀

	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:  AT;  Effect Codes:  POP; Rejection Code:  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:  A;  Effect Codes:  POP,PHY;
Rejection Code:  NO ENDPOINT(SMM).

	29. 	Naqvi, S. M., Hawkins, R., and Naqvi, N. H. (1987). Mortality
Response and LC50 Values for Juvenile and Adult Crayfish, Procambarus
clarkii Exposed to Thiodan (Insecticide), Treflan, Msma, Oust. 
Environ.Pollut. 48: 275-283.

EcoReference No.: 12802

Chemical of Concern: SMM,TFN;  Habitat:  A;  Effect Codes:  MOR;
Rejection Code:  NO CONTROL(SMM).

	30. 	Nishida, N., Farmer, J. D., Kodavanti, P. R. S., Tilson, H. A.,
and MacPhail, R. C. (1997). Effects of Acute and Repeated Exposures to
Aroclor 1254 in Adult Rats:  Motor Activity and Flavor Aversion
Conditioning.  Fundam.Appl.Toxicol.  40: 68-74.

EcoReference No.: 90537

Chemical of Concern: SAC,PCB;  Habitat:  T;  Effect Codes:  GRO,BEH;
Rejection Code:  NO CONTROL,ENDPOINT(SAC),OK(PCB).

	31. 	Office of Pesticide Programs (2000). Pesticide Ecotoxicity
Database (Formerly:  Environmental Effects Database (EEDB)). 
Environmental Fate and Effects Division, U.S.EPA, Washington, D.C.

EcoReference No.: 344  Rejection Code: Secondary Duplicative Data

	32. 	Peele, D. B., Farmer, J. D., and MacPhail, R. C. (1988).
Behavioral Consequences of Chelator Administration in Acute Cadmium
Toxicity.  Fundam.Appl.Toxicol. 11: 416-428.

EcoReference No.: 90538

Chemical of Concern: SAC,CdCl;  Habitat:  T;  Effect Codes:  GRO,BEH;
Rejection Code:  NO ENDPOINT(SAC).

	33. 	Roshon, R. D., McCann, J. H., Thompson, D. G., and Stephenson, G.
R. (1999). Effects of Seven Forestry Management Herbicides on
Myriophyllum sibiricum, as Compared with Other Nontarget Aquatic
Organisms.  Can.J.For.Res. 29: 1158-1169.

EcoReference No.: 60978

Chemical of Concern: 24DXY,GYP,HXZ,IZP,MSFM,SMM,TPR;  Habitat:  A; 
Effect Codes:  GRO,MOR; Rejection Code:  NO CONTROL(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:  T;  Effect Codes:  PHY; Rejection Code:  NO ENDPOINT(ALL
CHEMS).

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

EcoReference No.: 90533

Chemical of Concern: SMM;  Habitat:  A;  Effect Codes:  POP,PHY;
Rejection Code:  NO ENDPOINT(SMM)

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

  All first-order rates / degradation half-lives discussed in this
document, were, unless otherwised specified, calculated from linear
regression of log-transformed decay data.

  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.

 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 
 REF _Ref179348297 \h  \* MERGEFORMAT  APPENDIX C:  Ecological Aquatic
Exposure Modeling .

 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. 

 PAGE   2 

 PAGE   31 

 PAGE   112 

 PAGE   113 

Sulfometuron Methyl Applied To Foliage Via Aerial And Ground Sprays

Indirect effects

Gill/Integument Uptake & Ingestion

Vascular Aquatic 

Plants

Individual Animals

Reduced survival, growth and/or reproduction

Attribute Change

Aquatic 

Animals 

Exposure Point

Stressor 

Nonvascular Aquatic Plants

Plant Population

Reduced Population Growth

Receptor

Source/ Transport

Pathways 

Surface Water/ Sediment

Spray

Drift

Direct Contact & 

Root Uptake

Source/ Exposure Media

Runoff/

Erosion

Leaching/ Infiltration

Indirect effects

Groundwater

Individual Plants

Reduced Survival and Growth

Groundwater

Individual Plants

Reduced Survival and Growth

Direct Contact/ 

Root Uptake

Terrestrial 

Plants

Individual Animals

Reduced survival, growth and/or reproduction

Attribute Change

Terrestrial 

Animals

Ingestion

Exposure Point

Foliage/Soil

Inhalation/ Dermal

Air/ Soil Particles

Terrestrial Food (foliage, fruits insects)

Source/ Exposure Media

Leaching/ Infiltration

Runoff/

Erosion

Spray

Drift

Direct Deposition

Volatilization/Wind Erosion

Receptor

Source/ Transport

Pathways 

Stressor 

Sulfometuron methyl applied to foliage via aerial and ground sprays