2

(DCI) to address uncertainties surrounding the environmental fate and potential ecological 

effects of sulfometuron methyl.
3

Problem Formulation for the Environmental Fate, 

Ecological Risk, Endangered Species, and Human Health

Drinking Water Exposure Assessments in Support of the 

Registration Review of Sulfometuron Methyl

SULFOMETURON METHYL

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

SMILES: n1c(C)cc(C)nc1NC(=O)NS(=O)(=O)c2ccccc2C(=O)OC

Chemical Name:

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

Prepared by:

Robin Sternberg, Ecologist, ERB I

Michael Barrett, Senior Chemist, ERB V

U.S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Keith Sappington, Biologist, ERB V

José L. Meléndez, Chemist, ERB V

Approved by:

Mah Shamim, PhD, Branch Chief, ERB V

Date: December 5, 2012
4

TABLE OF CONTENTS

1. INTRODUCTION.................................................................................................................................................. 5

2. PREVIOUS CONCLUSIONS...................................................................................................................................7

ECOLOGICAL RISK ASSESSMENTS.......................................................................................................................................7

DRINKING WATER EXPOSURE ASSESSMENTS .......................................................................................................................8

CLEAN WATER ACT PROGRAMS........................................................................................................................................9

3. FATE SUMMARY................................................................................................................................................. 9

3.1. CHEMISTRY AND ENVIRONMENTAL FATE OF PARENT ..............................................................................................9

3.2. TRANSFORMATION PRODUCTS .........................................................................................................................19

4. RECEPTORS................................................................................................................................................. 21

4.1. EFFECTS OF PARENT SULFOMETURON METHYL TO AQUATIC AND TERRESTRIAL ORGANISMS.........................................21

4.2. EFFECTS OF DEGRADATES TO AQUATIC AND TERRESTRIAL ORGANISMS ......................................................................23

4.2.1. Overview ..................................................................................................................................................23

4.2.2. Analysis of Available Toxicity Data...........................................................................................................24

4.3. ECOLOGICAL INCIDENTS ..................................................................................................................................29

5. EXPOSURE PATHWAYS OF CONCERN.......................................................................................................... 32

6. ANALYSIS PLAN............................................................................................................................................... 32

6.1. STRESSORS OF CONCERN.................................................................................................................................32

6.2. MEASURES OF EXPOSURE ...............................................................................................................................33

6.3. MEASURES OF EFFECT ....................................................................................................................................33

6.4. ENDANGERED SPECIES ASSESSMENTS ................................................................................................................34

6.5. ENDOCRINE DISRUPTOR SCREENING PROGRAM ...................................................................................................34

7. PRELIMINARY IDENTIFICATION OF DATA GAPS ............................................................................................... 34

Environmental Fate Data Requirements............................................................................................................35

Ecological Effects Data Requirements................................................................................................................37

APPENDIX 1. SUBMITTED ENVIRONMENTAL FATE AND EFFECTS STUDIES .......................................................... 42

ENVIRONMENTAL FATE STUDIES ......................................................................................................................... 42

SUBMITTED EFFECTS STUDIES:................................................................................................................................50

APPENDIX 2: STRUCTURES AND CHEMICAL NAMES OF SULFOMETURON METHYL METABOLITES ....................... 55

APPENDIX 3. UNCERTAINTIES RELATED TO THE USE OF INCIDENT INFORMATION FROM THE ECOLOGICAL 

INCIDENT INFORMATION SYSTEM ....................................................................................................................... 57

APPENDIX 4. SIP V.1.0 INPUTS AND OUTPUTS .................................................................................................... 59

APPENDIX 5. STIR V.1.0 INPUTS AND OUTPUTS .................................................................................................. 61

APPENDIX 6. THE RISK QUOTIENT METHOD AND LEVELS OF CONCERN .............................................................. 62

APPENDIX 7. TOXICITY ENDPOINTS FOR SULFOMETURON METHYL AND ITS DEGRADATES AND ANALOGUES.... 64

Degradate toxicity in comparison to parent toxicity..........................................................................................66
5

1. Introduction

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

and ecological effects of the registered uses of sulfometuron methyl ( 2-[[[[(4,6-Dimethyl-2-

pyrimidinyl) amino] carbonyl] amino] sulfonyl] benzoic acid, methyl ester). Sulfometuronmethyl is a sulfonylurea herbicide; this class of pesticides has been targeted by the Agency for 

the evaluation of common degradates and with respect to their modes of action and toxicological 

profiles which will be addressed in this document. Similar to other sulfonylurea herbicides, the 

mode of action of parent 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. ALS is also known as acetohydroxyacid synthase 

(AHAS) (HRAC Group B)1. This particular mode of action appears to impart herbicidal activity 

and require relatively low concentrations of the chemical to produce such effects, as evidenced 

by the generally low range of labeled rates.

In sulfometuron methyl the sulfonylurea moiety serves as a “bridge” between an aminopyrimidine (the “Q” moiety on the -NH- or amine side of bridge) and an esterified benzoic acid 

(“A” on the -SO2- or sulfonyl side of bridge) ring structures in the molecule as shown below in 

Figure 1. 

Generic Molecular Structure for Sulfonylurea Herbicides

 1 URL: http://www.hracglobal.com/ (accessed 08/02/2012)

Stidham, Mark A. 1991. Herbicides That Inhibit Acetohydroxyacid Synthase. Weed Science 39(3):428-434.
6

Sulfometuron Methyl Chemical Structure

Figure 1. Molecular structure of a sulfonylurea and sulfometuron methyl.

Many sulfonylurea herbicides share similar A and Q moieties, these will be discussed further in 

the Toxicity discussion below. 

Sulfometuron-methyl is labeled for use on rangeland, uncultivated agriculture areas, and

swamps/marshes/bogs after water has receded, seasonally dry flood areas2, rights of way, forest 

trees, ornamental lawns and turf, ornamental woody shrubs and vines, ornamental and/or shade 

trees, drainage systems, drained canals, uncultivated nonagricultural areas, loading docks 

(outdoor), and storage areas (outdoor). The uses of sulfometuron methyl are further summarized 

in the “BEAD Chemical Profile for Registration Review: Sulfometuron-methyl (122001) dated 

5/30/2012. Recent label changes in response to the Reregistration Eligibility Document have 

been approved by the Agency (memorandum entitled “Clarifications to Sulfometuron Methyl 

Label Table Dated October 2011” from OPP Pesticide Re-Evaluation Division to Registration 

Division). Currently labels are adopting measures from the Reregistration Eligibility Decision 

(RED) to mitigate identified risks. Major changes on the new labels will be that all uses will be 

limited to a maximum single rate of 0.199 lb ai / A for forestry uses and 0.281 lb ai / A for other 

(non-agricultural) uses, aerial applications of liquid formulations will be limited to rotary 

aircraft, and numerical buffers will be required for applications made near sensitive sites. For the 

current Problem Formulation, the Agency has assessed the subject sulfometuron methyl labels as 

they are currently registered. The Agency acknowledges that risks are expected to be reduced 

once mitigation has been fully implemented, and anticipates that the preliminary risk assessment 

for sulfometuron methyl will reflect label changes required via the RED

Sulfometuron-methyl is formulated as a water dispersible granular and soluble concentrate; and 

is applied using ground or aerial application methods. On current labels both the maximum

single and annual application rates are up to 0.375 lb a.i. / acre or less depending on the use site

 2 The labels prohibit applications to natural or man-made bodies of water such as lakes, reservoirs, ponds, streams, 

and canals.
7

(the range of application rates allowed by site is summarized in detail in the revised risk 

assessment for the RED, DP Barcode D354292, 7/14/2008; only rangeland uses have been added 

since then).

This document will provide a plan for analyzing data relevant to environmental and human 

health risk for sulfometuron-methyl. Additionally, this problem formulation is intended to 

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

relative to a sulfometuron methyl ecological risk assessment. 

EFED will use application scenarios that result in maximum exposure for a given use for the risk 

assessment. Any absence of information on the labels that specifies the maximum single 

application rate, the application interval, the annual maximum rate allowed (lbs a.i./year), or 

application method will result in conservative assumptions as illustrated in the following 

examples:

• A maximum single application rate is specified with a re-application interval of 7 days 

without specifying a maximum annual rate may result in an assumption of 52 

applications with 7-day intervals;

• A label that does not preclude aerial applications will likely result in an assumption of 

aerial pesticide applications;

2. Previous Conclusions

Recent EFED reviews for sulfometuron methyl include:

• DP Barcode D354292; 7/14/2008: Reregistration eligibility EFED chapter, revised.

• DP Barcode: D355888; 2/2/2009: New use for rangeland restoration.

• DP Barcode D334277; 2/8/2009; Drinking water assessment.

• DP Barcode D346187and D346188; 4/2008: Review of sulfometuron-methyl spray drift 

study.

• DP Barcode D346169; 11/2009: Response to RED comments and refined spray drift 

analysis by EFED.

Risk assessment conclusions from these assessments are summarized below.

Ecological Risk Assessments

In previous ecological risk assessments concerns were identified for direct effects on terrestrial 

and aquatic plants from sulfometuron methyl uses. Although direct effects on birds, mammals, 

fish, and aquatic invertebrates were not identified some uncertainties remain and these are 

discussed below.

Important exposure pathways include leaching to groundwater, spray drift, and runoff to surface 

water. Although the residues of concern are believed to be for parent only, it is important to note 

the exposure level to degradates can be equal or higher than to parent (an analysis of the 

potential for risk from exposure to degradates is also included in this document).
8

At the maximum registered application rate for sulfometuron methyl (0.375 lb a.i./A), LOCs for 

direct effects on aquatic and terrestrial animals are not exceeded. Lack of risk from direct effects 

on animals is consistent with the mode of action of sulfometuron methyl and findings from other 

sulfonylurea risk assessments. 

Potential risks to aquatic and terrestrial plants have been identified with LOCs exceeded for 

terrestrial and aquatic plants at all application rates. This is the case because sulfometuron 

methyl is by design a herbicide with especially high activity on some sensitive plant species and 

it cannot be assumed that any exposed plant is less sensitive in the absence of specific toxicity 

data for the species in question. 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)3. Risks to plants from groundwater 

exposure were evaluated and determined to not exceed LOCs. 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 at risk from indirect effects 

resulting from potential direct effects to aquatic or terrestrial plants. 

Use of ‘typical’ application rates as reported by the registrants would result in RQs significantly 

lower than annual application of the maximum application rate (for example, because 

applications apparently are only rarely applied more than once or twice every several years, not 

annually as the current labels allow), however, the typical rates may still result in RQs above 

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 use. 

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.

Drinking Water Exposure Assessments

A drinking water exposure assessment for the proposed new use on rhubarb was conducted for 

sulfometuron-methyl as part of the Reregistration Eligibility Decision in 2008 (USEPA, DP 

Barcode D334277; 2/14/2008; EFED ecological risk assessment chapter {revised} for 

reregistration eligibility). For surface water, the acute screening value was 31.98 ppb and the 

chronic was 14.51 ppb. The groundwater screening concentration was 0.33 ppb. These values 

represent upper-bound estimates of the concentrations that might be found in surface water (a 

vulnerable reservoir) and groundwater for drinking water due to the use of sulfometuron methyl 

 3 Endangered / listed species assessments require a more conservative LOC assumption resulting in higher estimated 

RQs for the same level of exposure.
9

at the maximum allowable rate within the watershed. Exposure estimates were also generated 

for the total residues of sulfometuron methyl which include sulfometuron-methyl and major 

degradates such as a pyrimidine amine, a sulfonamide degradate, and saccharin (see Appendix 1 

for structures and chemical names of degradates). For surface water sulfometuron methyl total 

residue exposure the acute value was 32.35 ppb and the chronic was 21.82 ppb. The 

groundwater screening concentration was 1.13 ppb. Overall, this screening level analysis 

showed that even if all degradates of sulfometuron methyl are included in a drinking water 

assessment acute exposure is not significantly increased and chronic exposure is increased by 

about 50% compared to the estimated exposure to parent sulfometuron methyl alone.

Clean Water Act Programs

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

impaired under section 303(d) of the Clean Water Act. No Total Maximum Daily Load (TMDL) 

criteria have been developed for sulfometuron methyl. Aquatic benchmarks have been 

established for sulfometuron methyl and are summarized in Table 1. Details are available at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm. Any data submitted or 

otherwise located as part of the Registration Review process may be used to update aquatic life 

benchmarks if applicable. 

Table 1. OPP freshwater Aquatic Life Benchmarks (μg / L).

Organism ------ Fish Invertebrates

Nonvascular 

Plants

Vascular 

Plants

Exposure Duration -- Acute Chronic Acute Chronic Acute Acute

Pesticide:

Sulfometuron methyl

> 

74,000 — > 75,000 97,000 4.6 0.48

3. Fate Summary 

3.1. Chemistry and Environmental Fate of Parent

The physicochemical properties (Table 2) and the body of environmental fate data submitted

(Table 3) demonstrates sulfometuron methyl is mobile (all measured Koc values < 100 and 

persistent (degradation half-lives from a few weeks to several months in various laboratory and 

field studies) in the environment. Sulfometuron methyl is more soluble in neutral and alkaline 

water than in acidic water. The major route of dissipation for sulfometuron methyl is aerobic and 
10

anaerobic degradation / metabolism in soil and water (pseudo first-order degradation half-lives4

generally around 2 to 6 months), with hydrolysis potentially dominant under acidic conditions. 

However, sulfometuron methyl degradation rate and mobility in the environment can be 

characterized as highly variable – significantly affected by soil and water properties such as pH 

and organic matter and with often significantly increased resistance to degradation in soil over 

time.

As summarized in Table 3 and previously in the Ecological Fate and Effects chapter to the 

sulfometuron-methyl RED (DP Barcode D354292) the sulfometuron methyl environmental fate 

data show some unusual characteristics of sulfometuron methyl in that some field dissipation 

rates at some sites are slower than the degradation rates measured in aerobic soil metabolism 

studies. Furthermore, both measured laboratory degradation and field dissipation rates are in 

some cases slower than the hydrolysis rate measured in the laboratory (particularly under acidic 

conditions) for sulfometuron methyl. These data indicate that the fate of sulfometuron methyl 

may be highly site dependent – an important factor to consider in risk assessments.

Table 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]

amino] sulfonyl] benzoic acid, methyl ester

Structure

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 

 4

 All first-order rates / degradation half-lives discussed in this document, were, unless otherwised specified, 

calculated from linear regression of log-transformed decay data.
11

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Hydrolysis

835.2120

[161-1]

t1⁄2= 8.8 days @ 25 oC, pH 5;

t1⁄2=139 days @ 25 oC, pH 7;

t1⁄2= 224 days @ 25 o

C, pH 9.

Major degradates (from cleavage of the sulfonylurea bridge): 

Sulfonamide – only in acidic water

Saccharin – all pH levels

Pyrimidine amine – all pH levels

42715201

Direct photolysis 

in water

835.2240

[161-2]

Combined labels results:

t1⁄2= 428 days @ 24 oC, pH 5;

t1⁄2= stable @ 24 o

C, pH 7;

t1⁄2= stable @ 24 o

C, pH 9.

(calculated by the difference in degradation rates between irradiated and dark 

controls and adjusting for typical light levels on sunny days)

Major degradates (irradiated water):

pH 5: sulfonamide, pyrimidine amine;

pH 7: none;

pH 9: none.

42182401

43174101

(suppleme

ntal)

Previous 

study 

#41672812 

is 

supplement

al.

Photolysis on soil

835.2410

[161-3]

t1⁄2= 72.1 days @ 25 oC5, 

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

 5 Hydrolysis may have been a significant factor in the dark controls. The reported pH of the test soil (Keyport silt 

loam) was 6.8, but the soil series tends to be more acidic which would likely promote signifincant abiotic hydrolysis.
12

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Aerobic soil 

metabolism

835.4100

[162-1]

Study with [pyrimidine-2-

14C] Sulfometuron Methyl

Soil: Keyport Silt loam (pH 6.3, 1.6% O.C.) from Delaware (0.68 mg 

a.i./kg

First Order t1⁄2: 57.8 days (r2 = 0.9239).

Observed DT50: 23 days.

Observed DT90: 110 days.

Sterile soil First Order t1⁄2: 364 days

Major transformation products:

Pyrimidine amine (maximum 41.0% of the applied at 30 days, Final: 

11.4% at 365 days)

Pyrimidine-ol (maximum 10.5% of the applied at 63 days, 4.6% at 365 

days).

CO2 (maximum 53.1% of applied).

Minor transformation products:

Free acid sulfometuron methyl (up to 4.1%).

Pyrimidine urea (up to 2.4%). 

42091401

Aerobic soil 

metabolism

835.4100

[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) results (an exaggerated rate of 1.0 mg ai/kg was also tested).

First Order t1⁄2: 51.1 days (linear; r

2 = 0.9664).

Observed DT50: 29 days.

Observed DT90: 162 days.

(values are calculated from results with 2 application rates: 0.12 and 1.0 mg 

a.i. / kg with the higher rate study added to facilitate more precise 

characterization of degradation pathways. 

Major transformation products:

Sulfonamide (maximum 17% of applied at 0 days, Final: <1% at 168 days.

Saccharin (maximum 30% of applied at 14 days, 3% at 168 days)

At the high rate sulfonamide was up to 11% at 14 days and <1% at 168 days 

and saccharin was up to 37% at 28 days and 14% at 168 days.

Minor (possibly major) products:

Free acid sulfonamide (Maximum of % at 168 days); at the exaggerated rate 

it was 22% at 72 days and declined to 2% at 168 days).

43174102 

and 

245375
13

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Anaerobic aquatic 

metabolism

835.4200

[162-3]

1. Study performed with [pyrimidine-2-

14C] Sulfometuron Methyl

Matrix: Bradenton Pond water-sand sediment.

First Order t1⁄2: 37.4 days (r2 = 0.6125).

Observed total system DT50: 22 to 61 days (inconsistent decline data).

Observed total system DT90: 102 days.

Major transformation products (both systems):

free acid sulfometuron methyl (Up to 53.9% at 28 days; Final: 3.6% at 

364 days).

pyrimidine amine (Up to 52.7% at 168 days; Final: 27.0% at 364 days).

Minor identified transformation products:

pyrimidine-ol.

 CO2.

Matrix: Landenberg Pond water-sandy loam sediment.

First Order t1⁄2; 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 (Up to 55.9% at 28 days; Final: 0.8% at 

364 days).

pyrimidine amine (Up to 71.4% at 112 days; Final: 56.2% at 364 days).

Minor identified transformation products:

pyrimidine-ol.

CO2.

42091402 

and 

43188601
14

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Anaerobic aquatic 

metabolism

835.4400

[162-3]

2. Study with [phenyl-U14C] 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 t1⁄2; total system: 104 days (r2 = 0.4883)*.

Observed DT50 in total system: ca. 21 days.

Sterile t1⁄2; total system: 44 days

* Residues were highly variable over time data.

Matrix: Pond water-silt loam sediment from Landenberg, Pennsylvania.

(water pH 5.8 . Sediment: pH 5.6; O.C. = 2.1 %).

First Order t1⁄2; total system: 87 days (r2 = 0.3577).

Observed DT50 in total system: ca. 28 days.

Sterile t1⁄2; 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 t1⁄2; total system: 77 days (r2 = 0.5853).

Observed DT50 in total system: ca. 70 days.

Sterile t1⁄2; total system: 399 days

Matrix: Pond water-silt loam sediment from Walnut Grove, Tennessee. 

(water pH 5.5 . Sediment: pH 5.1; O.C. = 0.5 %).

First Order t1⁄2; total system: 73 days (r2 = 0.5691).

Observed DT50 in total system: ca. 28 days.

Sterile t1⁄2; total system: 95 days

Major transformation products:

saccharin.

free acid sulfonamide.

Minor identified transformation products:

Methyl-2-aminocarbonyl(aminosulfonyl)benzoate.

4413010-

20 

(143540)
15

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Aerobic aquatic 

metabolism

835.4300

[162-4]

Study performed with [pyrimidine-2-

14C] Sulfometuron Methyl

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

First Order t1⁄2; 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 t1⁄2; total system: 187.3 days (r2 = 0.5713).

Observed DT50 in total system: >>39 days (study termination).

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
16

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Adsorption/

Desorption 

(Kd and 

Koc in L K1g-1

)

835.1230

[163-1]

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: Negative.

Koc: Negative. 

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
17

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Adsorption/

Desorption 

Of Degradates

Sulfometuron Pyrimidine amine 

This study is in review.

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

4-, 6-dimethoxy rather than 4-, 6-dimethyl substitution of the pyrimidine 

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.

Saccharin

This study is in review.

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

When tested as a degradate of metsulfuron methyl 

(http://ec.europa.eu/food/plant/protection/evaluation/existactive/list1-

13_en.pdf )

Sulfometuron Sulfonamide

This study is in review.

42789301
18

Table 3. Key results of sulfometuron methyl environmental fate studies.

Parameter

Guideline #

[Old Guideline #]

Value1 MRID(s)

Terrestrial 

Field/Lysimeter

Dissipation 2

835.6100 

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)

Pyrimidine 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

43212101 

and 

43637101

Forestry 

Dissipation

835.6300

Gainesville, FL sand soil: pH 4.0, 0.62% O.M.

(study in review)

Scooba, Mississippi silty clay loam soil: pH 4.5, 4.0% O.M.

(study in review)

42091404

and

43174104

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 

possibly more appropriate (little dissipation of the remaining residues in the top soil 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 sufficiently 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 top soil within 3 to 6 months.
19

Sulfometuron-methyl 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 toxicity of sulfometuron 

methyl to certain plant species at very low levels (i.e., at only a small fraction of the already low 

application rates) means that there is a risk for exposure at toxic levels at far distances from the 

application site via spray drift (discussed in greater detail in previous reviews). 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. 

The log KOW values for sulfometuron methyl are ≤1.03 and therefore, bioconcentration of the 

chemical in aquatic animal tissue is not expected.

3.2. Transformation Products

Like most other registered sulfonylurea herbicides, cleavage of the sulfonylurea bridge between 

two ring structures occurs early in the degradation of the molecule creating two separate 

degradation pathways with fractions of the parent molecule; in the case of sulfometuron methyl,

these are an esterified benzoic acid and a pyrimidine amine moiety. The rate at which the 

sulfonylurea bridge is cleaved is similar under anaerobic and aerobic conditions. Complete 

degradation / mineralization is more rapid under aerobic conditions. The hydrolytic cleavage of 

the sulfonylurea bridge generates a sulfonamide plus the aminopyrimidine (resulting in 

elimination of a carbon dioxide molecule); similar metabolites may be the products of other 

sulfonylurea herbicides (discussed in further detail below). The sulfonamide is further cyclized 

with the carbomethoxy group in the ortho position, yielding saccharin. Degradation by this same 

pathway occurs at a slower rate under sterile conditions. 

The most commonly formed and persistent environmental degradates are the sulfometuron 

sulfonamide, the sulfometuron pyrimidine amine, and saccharin; other degradates occur less 

commonly (see APPENDIX 2: Structures and Chemical Names of Sulfometuron methyl 

Metabolites). Deesterification from sulfometuron methyl to the free acid occurs, but this 

degradate does not appear to accumulate substantially. 
The sulfometuron methyl pyrimidine amine and benzoic acid methyl ester moieties are shared in similar 

or identical in a number of other sulfonylurea herbicides (all of these herbicides by definition share the 

sulfonylurea bridge) as listed below6:

“Q” Moiety

Pyrimidine amine (dimethyl):

Sulfometuron methyl

Pyrimidine amine (Other substituted –

usually methoxy- or dimethoxy-):

Amidosulfuron

Azimsulfuron

Bensulfuron

Chlorimuron

Flazasulfuron

Foramasulfuron

Halosulfuron methyl

Imazosulfuron

Mesosulfuron

Nicosulfuron

Orthosulfamuron

Primisulfuron methyl

Pyrazosulfuron

Rimsulfuron

Sulfosulfuron

“A” Moiety:

Benzoic acid ester:

Bensulfuron methyl

Chlorimuron ethyl

Ethametsulfuron methyl

Metsulfuron methyl

Primisulfuron methyl

Sulfometuron methyl

Tribenuron methyl

Benzoic ester with other ring substitution:

Idosulfuron

Triflusulfuron 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 three of the sulfometuron methyl degradates were studied in batch equilibrium adsorption / desorption 

studies, these studies are in review and these results have not yet been validated; therefore the following

values can only be considered suggestive of what the sorption characteristics of these compounds might 

be: saccharin Kfs were 0.03 to 0.27 and the pyrimidine amine Kfs were 0.17 to 3.70 in the four test soils 

(Table 3). This means saccharin might 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).

 6 Not all of the listed herbicides have registered uses in the United States. The “Q” and “A” moieties are defined in Section 1.
21

4. Receptors

4.1. Effects of Parent Sulfometuron Methyl to Aquatic and Terrestrial 

Organisms

A summary of toxicity data for sulfometuron methyl from registrant-submitted studies is provided in

Table 4. As expected, the acute toxicity of sulfometuron methyl to aquatic and terrestrial animals is 

very low (slightly to practically non-toxic) whereas its toxicity to plants is very high. This finding is 

consistent with the mode of action of sulfometuron methyl (i.e., inhibition of ALS) and is similar to 

toxicity findings from other sulfonylurea herbicides. The following data are not available for 

sulfometuron methyl:

• chronic reproductive toxicity data for fish, birds, and mammals, 

• chronic toxicity data for estuarine/marine invertebrates and fish, and

• acute toxicity data for a passerine species. 

In previous risk assessments the Levels of Concern (LOCs) for sulfometuron on sensitive terrestrial 

plant species have been shown to be exceeded by wide margins when exposure is calculated from 

sulfometuron methyl use at maximum label rates (e.g., DP Barcode D355888 and D354292) with spray 

drift a major route of exposure. LOCs are also exceeded for aquatic plants, but by much smaller margins 

than terrestrial plants.

LOCs are not exceeded for any terrestrial or aquatic animal taxa evaluated. Sulfometuron methyl is 

practically non-toxic to birds, mammals, and bees on an acute toxicity basis (Table 4). 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). Sulfometuron methyl is practically non-toxic or at most slightly toxic for aquatic 

animal taxa (Table 4). This compares with expected peak exposure levels of 0.032 mg/L or less in 

surface waters even when sulfometuron methyl is applied at maximum label rates throughout the 

watershed (Table 5).

Table 4. Summary of the Endpoints from Aquatic and Terrestrial Toxicity Studies for 

Sulfometuron Methyl

Taxonomic 

Group

Study 

Type

Species Toxicity Value Acute 

Toxicity 

Classification

Source

Freshwater 

fish

Acute

Rainbow trout

(Oncorhynchus 

mykiss)

96-hr LC50 > 148 mg a.i./L

96-hr NOEC = 148 mg a.i./L

(no mortality)

Practically 

non-toxic

MRID 43501802*

Acceptable

Bluegill sunfish

(Lepomis 

macrochirus)

96-hr LC50 > 150 mg a.i./L

96-hr NOEC = 150 mg a.i./L

(no mortality)

Practically 

non-toxic

MRID 43501801

Acceptable

Chronic No data
22

Taxonomic 

Group

Study 

Type

Species Toxicity Value Acute 

Toxicity 

Classification

Source

Freshwater 

invertebrates

Acute

Water flea

(Daphnia 

magna)

96-hr EC50 > 150 mg a.i./L

96-hr NOEC = 150 mg a.i./L

Practically 

non-toxic

MRID 43501803

Acceptable

Chronic

Water flea

(Daphnia 

magna)

21-day NOEC = 97 mg 

a.i./L N/A MRID 41672806*

Acceptable

Saltwater 

fish

Acute

Sheepshead 

minnow 

(Cyprinodon 

variegatus)

96-hr LC50 > 45 mg a.i./L

96-hr NOEC = 45 mg a.i./L

At most

slightly toxic1

MRID 41672803

Supplemental**

Chronic No data

Saltwater 

invertebrates

Acute

Eastern oyster 

(Crassostrea 

virginica)

48-hr IC50 > 38.2 mg a.i../L

48-hr NOEC = 38.2 mg a.i./L

At most 

slightly toxic1

MRID 41672805

Supplemental**

Mysid shrimp

(Mysidopsis 

bahia)

96-hr LC50 > 44.8 mg a.i./L

96-hr NOEC = 44.8 mg a.i./L

(no mortality)

At most 

slightly toxic1

MRID 41672804

Supplemental**

Chronic No data

Aquatic 

plants

Vascular

Duckweed

(Lemna gibba

G3)

14-day EC50 = 0.45 μg a.i./L

14-day NOEC = 0.207 μg 

a.i./L

N/A MRID 43538503*

Acceptable

Nonvascular

Green alga

(Selenastrum 

capricornutum)

5-day EC50 = 4.3 μg a.i./L

5-day NOEC = 0.63 μg a.i./L

(based on cell density)

N/A MRID 41680102*

Acceptable

Blue-green alga

(Anabaena flosaqua)

5-day EC50 = 73 μg a.i./L

5-day NOEC = 14 μg a.i./L

(based on cell density)

N/A MRID 43538502*

Acceptable

Freshwater 

diatom 

(Navicula 

pelliculosa)

5-day EC50 > 370 μg a.i./L

5-day NOEC = 370 μg a.i./L

(based on cell density)

N/A MRID 43538502*

Acceptable

Marine diatom 

(Skeletonema 

costatum)

5-day EC50 > 410 μg a.i./L

5-day NOEC = 410 μg a.i./L

(based on cell density)

N/A MRID 43538502*

Acceptable

Birds

Acute

Mallard duck

(Anas 

platyrhynchos)

14-day LD50 > 4650 mg 

a.i./kg-bw

(no mortality)

Practically 

non-toxic

MRID 00078700

Acceptable

Passerine No data

Sub-acute 

dietary

Mallard duck

(Anas 

platyrhynchos)

8-day LD50 > 4600 mg 

a.i./kg-diet

(no mortality)

At most 

slightly toxic1

MRID 00071414

Acceptable

Northern 

bobwhite quail

(Colinus 

virginianus)

8-day LD50 > 5620 mg

a.i./kg-bw 

(no mortality)

Practically 

non-toxic

MRID 00088813

Acceptable

Chronic No data

Mammals

Acute Rat 14-day LD50 > 5000 mg 

a.i./kg-bw

Practically 

non-toxic MRID 43089201

Teratogenicity2 Rabbit NOAEC = 300 mg a.i./kgbw/d N/A MRID 00078798
23

Taxonomic 

Group

Study 

Type

Species Toxicity Value Acute 

Toxicity 

Classification

Source

Terrestrial 

invertebrates

Acute 

contact

Honeybee

(Apis mellifera)

48-hr LD50 > 100 μg a.i./bee

48-hr NOEC = 100 a.i. 

μg/bee

Practically 

non-toxic

MRID 41672810

Acceptable

Terrestrial 

plants

Seedling 

emergence

Most sensitive monocot

N/A MRID 43538501*

Acceptable

Sorghum EC25 = 1.9x10-4 lb a.i./A

EC05 = 4.3x10-5 lb a.i./A+

(based on shoot height)

Most sensitive dicot

Sugar beet EC25 = 3.1x10-5 lb a.i./A

NOEC = 2.9x10-5 lb a.i./A

(based on shoot dry weight)

Vegetative 

vigor

Most sensitive monocot

N/A MRID 43538501*

Acceptable

Corn EC25 = 3.7x10-5 lb a.i./A

EC05 = 8.4x10-6 lb a.i./A+

(based on shoot dry weight)

Most sensitive dicot

Soybean EC25 = 1.8x10-5 lb a.i./A

EC05 = 1.0x10-6 lb a.i./A+

(based on shoot dry weight)

N/A = not applicable

1 Toxicity endpoint was greater than the highest concentration tested, which fell in the slightly toxic category. 2 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 42385705 and 42385706). 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. A developmental toxicity study with rat (MRID 00078796) was also classified as unacceptable by 

HED.

* Toxicity values were revised after a re-review and analysis of the study results in 2007 (MRIDs 41672806, 43501802, and 

43538501) and 2012 (MRIDs 41680102, 435385032, and 43538503).

** Supplemental classification due to high variability in measured test concentrations and uncertainty in exposure to 

dissolved sulfometuron methyl (i.e., test samples were not centrifuged prior to analysis). + EC05 is reported for estimating effects to listed (endangered) terrestrial plants because the NOAEC equaled or exceeded the 

EC25.

Table 5. Summary of Estimated Environmental Concentrations (EECs) for Aquatic Exposure to 

Parent Sulfometuron Methyl as Modeled for the 2008 Ecological Risk Assessment for the 

Reregistration of Sulfometuron Methyl (USEPA, 2008)

Method of Application Peak EEC (mg/L) 21-day EEC (mg/L) 60-day EEC (mg/L)

Ground 0.0046-0.0261 0.0004-0.0216 0.0003-0.0155

Aerial 0.0012-0.0315 0.0011-0.0262 0.0010-0.0205 1 BOLD indicates largest EEC; values are estimated 1 in10 year return frequency concentrations after long-term application 

at maximum labeled rates throughout the watershed.

4.2. Effects of degradates to aquatic and terrestrial organisms

4.2.1. Overview

Five degradates were identified as major products in at least one environmental fate study: saccharin, 

pyrimidine amine, pyrimidine-ol, sulfonamide, and free acid sulfonamide (full chemical names and 
24

structures of each are given in Appendix 2). The major degradates of sulfometuron methyl form by 

bridge cleavage producing fractional degradates having a toxicological profile that may be very different 

from the parent molecule and, given the low application rates of sulfometuron methyl, the degradates

need to be fairly potent toxins to a particular class of organisms to trigger a risk concern.

From the substantial difference in structure from the parent molecule it appears unlikely that the

identified major degradates would significantly contribute to toxicity to sensitive plants on or near the 

application site. However, no direct data have been submitted to support this hypothesis. We also 

explored the potential for ecological effects from these degradates and have concluded that the 

preponderance of the available evidence indicates that ecological effects from sulfometuron use likely

primarily arise from the toxicity of sulfometuron per se to sensitive terrestrial or aquatic plant and algal 

species (including indirect effects on organisms that may be impacted by these direct effects on plants 

and algae).

For this Problem Formulation we analyzed structure-activity relationships using the Ecological Structure 

Activity Relationships (ECOSAR) version 1.00 model and additionally performed some comparisons 

with toxicity data from related degradates of other Note that ECOSAR, only estimates effect levels for 

aquatic species (and does not include aquatic macrophyte estimates). In terms of effects on terrestrial 

species we note that, while no direct data are available for degradate effects on terrestrial organisms, 

exposure to degradates on or near application areas will be lower than to parent because of dissipation 

processes as well as because the mass of each of the degradate molecules is much lower than the mass of 

the parent sulfometuron methyl molecule. 

4.2.2. Analysis of Available Toxicity Data

Direct toxicity testing is only available for the saccharin degradate. In the absence of toxicity 

data for the effects of the other degradates on the growth, reproduction, development, and 

survival of aquatic animals and plants, predicted acute and chronic toxicity values for pyrimidine 

amine, pyrimidine-ol, sulfonamide, and free acid sulfonamide were generated using ECOSAR 

which is based on quantitative structure activity relationships (QSAR) for effects on fish, 

daphnids, and green algae (effects on aquatic and terrestrial plants are not estimated). Predicted 

chronic toxicity values were also generated for saccharin since no chronic toxicity data were 

submitted for saccharin.

ECOSAR-predicted toxicity (and, when available, measured toxicity) values were compared to 

predicted estimated environmental concentrations (EECs) to determine whether additional degradate 

toxicity data could add value to the Registration Review ecological risk assessment (these comparisons 

are summarized in . Since EECs cannot be reliably modeled individually for the degradates due to the 

lack of appropriate data on the environmental fate of these compounds, predicted EECs for the 

degradates were conservatively assumed to be similar to those of the parent compound sulfometuron 

methyl

7

. EECs for sulfometuron methyl were taken from the 2008 ecological risk assessment for the 

reregistration of sulfometuron methyl (USEPA, 2008).

 7 The amount of each degradate formed is expected to be less than the amount of parent applied because of incomplete 

conversion (the degradates also form in smaller masses because the molecular weights of major degradates formed by 
25

An overall summary of the measured and estimated levels for toxic effects of parent and degradates is 

presented in Table 6.

 splitting of the parent molecule are substantially less than parent). Mobility of degradates is expected to be equivalent to or 

less than parent based up on available data. Degradate persistence could be somewhat higher than parent, but this is not 

expected to be enough to result in higher EECs.
Table 6. Summary of Available Measured and ECOSAR-Predicted Toxicity Endpoints for Sulfometuron methyl, its Major 

Degradates, and Analogues.

PREDICTED OR MEASURED EFFECT LEVELS

PARENT SULFOMETURON DEGRADATES8 ANALOG (to sulfom. 

Pyrimidine amine)

Organism Expected 

Exposure 

Level

Parent 

(measured)

Parent

(model)

PyrAm

(model)

PyrOl

(model)

SfnAm

(model)

SfnAc

(model

Sacch

(meas.)

Sacch

(model)

Dimethoxy

PyrAm

(measured)9

Dimethoxy

PyrAm

(modeled)

mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L

Fish

Acute

(96-hr 

LC50)

0.0315 >148.0 72 –

79.00 61.00 60.00

151 to 

26810 11669.0 124.00 --- 97.0011 79 to 920

Chronic

(~30-day) 0.0205 ND 0.47 –6.90 0.29 3.60 1.60 to 18.00 69.00 2.40 --- ND 0.38 to 90.00

Algae

Acute

(~ 96-hr 

LC50)

0.0315 0.0046 0.04 101.0 79.0 1.10 17.0 >10.0012 --- 120.0 0.92 to 130

Chronic

(# days?) 0.0262 ND 0.01 30.00 38.0 0.36 3.40 ND 3.4 ND ND

 8 PyrAm = Pyrimidine Amine PyrOl = Pyrimidine-ol SfnAm = Sulfonamide

SfnAc = Sulfonamide acid Sacch = Saccharin

9 Other company chemical codes for this metabolite include INJV0290, AE-F092944, and HOE092944. All measured aquatic toxicity data for this compound 

were retrieved from PPDB through a search for the string “2-amino-4,6-dimethoxypyrimidine” or for “AE-F092944” (duplicate entries for this compound in the 

database may not contain this information). The Pesticide Properties Database (aka. Footprint) may be accessed at: 

http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

2

 ChV = ECOSAR chronic toxicity value 10 Acute and chronic endpoint estimation ranges listed are based upon ester SAR classification for both fresh and saltwater fish species and amide classification 

for freshwater fish.

11 The species tested was Rainbow trout (Oncorhynchus mykiss). 12 Species tested: Green alga (Selenastrum capricornutum); MRID 48518910; in review. Reported value is 72-hr. LC50.
27

PREDICTED OR MEASURED EFFECT LEVELS

PARENT SULFOMETURON DEGRADATES8 ANALOG (to sulfom. 

Pyrimidine amine)

Organism Expected 

Exposure 

Level

Parent 

(measured)

Parent

(model)

PyrAm

(model)

PyrOl

(model)

SfnAm

(model)

SfnAc

(model

Sacch

(meas.)

Sacch

(model)

Dimethoxy

PyrAm

(measured)9

Dimethoxy

PyrAm

(modeled)

Daphnid

Acute

(~ 48-hr 

LC50)

0.0315 >150.0 40 –

154.0 700.0 16.0 98 to 

364 3192* >118 ---- >100 2.4 to 469

Chronic

~(21-day) 0.0262 97.0 0.53 -105.0 + 27 3.1 1.3 to 316 42+13 ND 1.70 24.0 0.05 – 36.0

Mysid shrimp

Acute

(~ 96-hr 

LC50)

0.0315 >44.8 121 ND ND 419.0 ND ND ND ND ND

Chronic

(# day ns) 0.0262 ND 16516 * ND ND 43000014 ND ND ND ND ND

Aquatic macrophyte (Lemna gibba)

Acute

(7- or 14-

day EC50)

0.0262 ND ND ND 62.0 ND ND 5.5 ND >100.0 ND

Saltwater fish

Acute

(96-hr 

LC50)

0.0315 >45.0 111.0 ND 67.0 256.0 ND ND ND ND ND

Chronic

(# day ns) 0.0262 ND 15 + ND ND 30+ ND ND ND ND ND

 13 + = The toxicity value was determined from a predicted SAR using established ACR ratios and ECOSAR regression techniques.

14 * = Predicted toxicity value may exceed compound’s aqueous solubility.
Saccharin Degradate

The saccharin degradate of sulfometuron methyl has numerous other anthropogenic origins in the 

environment including from its commercial use as an artificial sweetener and as a degradate of 

certain other pesticides (including several sulfonylurea herbicides) and pharmaceuticals. A literature 

review was not conducted for this Problem Formulation but we note here that, given its widespread 

use as a food additive and its other sources it is likely the published literature may provide additional 

information on the toxicity of saccharin.

Although some of this data is in review, a preliminary examination of the data indicates that 

saccharin is practically non-toxic to freshwater fish and invertebrates and mammals on an acute basis 

with toxicity endpoints comparable to those of parent sulfometuron methyl. However, saccharin is 4 

to 5 orders of magnitude less acutely toxic to aquatic plants than sulfometuron methyl. 

Acute aquatic toxicity values (5.5 to >124 mg/L) for saccharin are at least 2 orders of magnitude 

greater than the largest predicted peak EEC for sulfometuron methyl (0.0315 mg/L, and chronic 

aquatic toxicity values (1.7 to 3.4 mg/L) are at least two orders of magnitude greater than the largest 

predicted 21- and 60 day EECs (0.0205 to 0.0262 mg/L; Table 10). Thus there is little concern for 

risk to these organisms from exposure to saccharin. 

Other Degradates (pyrimidine amine, pyrimidine-ol, sulfonamide, and free acid 

sulfonamide)

No direct studies are available regarding the toxicity of the other four major or potentially major 

degradates so we used ECOSAR to predict levels at which toxic effects might occur and have 

compared these levels to the highest EECs for aquatic exposure to parent in Table 11 (as a 

conservative surrogate for the potential exposure to degradates).

15 All of the predicted toxic 

endpoints are multiple orders of magnitude lower than the highest parent sulfometuron methyl EECs 

except for the following:

• Pyrimidine amine predicted fish chronic toxicity value is as low as 0.29 mg/ L compared to a 

possible exposure level of 0.02 mg / L

• Sulfonamide predicted green algae chronic toxicity value is as low as 0.36 mg/ L compared 

to a possible exposure level of 0.02 mg / L

Even the above two predicted toxicity values are more than 10x less than the highest predicted 

parent EECs.

In addition to the measured values for degradates in Table 6, measured and estimated toxicity values 

for a structurally related degradate to the sulfometuron methyl dimethyl pyrmidineamine are 

presented in the same table and – this analysis also shows effects levels on plants and animals for 

this analog to occur only at levels of exposure much greater than expected to arise from the 

application of sulfometuron methyl. Additional details on this analysis are provided in Appendix 7.

 15 A rare exception to this would be where a degradate persists for multiple years in a water body with no outlet or 

turnover of water potentially resulting in long-term accumulation of residues in the water body.
29

4.3. Ecological Incidents

A preliminary review on July 25, 2012, of the Ecological Incident Information System (EIIS, version 

2.1), which is maintained by the Agency’s Office of Pesticide Programs, and the Avian Monitoring 

Information System (AIMS), which is maintained by the American Bird Conservancy, indicates a 

total of 34 reported ecological incidents associated with the use of sulfometuron methyl. These 

incidents are summarized in Table 7. This total excludes incidents classified as ‘unlikely’ or 

‘unrelated’ and only includes those incidents with certainty categories of ‘possible’, ‘probable’, and 

‘highly probable’ (for EIIS) and ‘possible’, ‘probable’, ‘likely’, ‘highly likely’ and ‘certain’ (for 

AIMS). Incidents classified as ‘unlikely’ the result of or ‘unrelated’ to sulfometuron methyl will not 

be included in this Problem Formulation or the ecological risk assessment conducted for Registration 

Review. 

All of the sulfometuron methyl incidents, excluding those classified as ‘unlikely’ or ‘unrelated’, 

occurred between 1985 and 2009. One of the sulfometuron methyl incidents involved aquatic 

animals, 2 involved terrestrial animals, and 33 involved plants. The certainty categories regarding 

the likelihood that the use of sulfometuron methyl caused the 34 incidents ranged from ‘highly 

probable’ (1 incident) to ‘possible’ (13 incidents); a majority of the incidents (20) were categorized 

as ‘probable.’ Twenty-two of the incidents were considered registered uses at the time of the 

incident, 6 involved misuses, and the legality of use was undetermined for 6 incidents. None of the 

incidents involved additional chemicals besides sulfometuron methyl. Sulfometuron methyl residues 

were not reported in any of the incident reports. All of the reported incidents for sulfometuron 

methyl involved 12 uses that are currently registered (agricultural area, apiary, forest, industrial site, 

municipal operation, peach, right-of-way, seedling, residential turf, utility plant, wheat, yard), and 

one in which the use site was not specified. The reported incidents associated with the 12 currently 

registered uses had certainty categories of ‘highly probable’, ‘probable’, and ‘possible’.

In the risk assessment, the incidents will be further evaluated to determine if the reported incidents 

represent current patterns of use for sulfometuron methyl. Examples of additional considerations are 

mitigation (e.g., reduced application rates), product cancellations, and changes in use patterns that 

have occurred since the date of the reported incident(s). 

In addition to the incidents recorded in EIIS and AIMS, additional incidents have been reported to 

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

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

reported in aggregate reports include those categorized as ‘minor fish and wildlife’ (W-B), ‘minor 

plant’ (P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ incidents include reports of 

adverse effects to insects and other terrestrial invertebrates. For sulfometuron methyl, registrants 

have reported 5 minor fish and wildlife incidents, 25 minor plant incidents, and 0 other non-target 

incidents. Unless additional information on these aggregated incidents becomes available, they will 

be assumed to be representative of registered uses of sulfometuron methyl in the risk assessment.
Table 7. Ecological Incidents Associated with Sulfometuron Methyl1

Incident 

Number

Taxa Involved Magnitude Year State Use Legality2 Certainty

I000903-001 Terrestrial plant Seeds, unknown woody plant: NR 1991 TX Agricultural area Registered use Probable

I000903-002 Terrestrial plant Peach, pecan: NR 1994 TX Agricultural area Registered use Probable

I000903-003

Aquatic animal, 

aquatic plant, 

terrestrial animal, 

terrestrial plant

Deer, forage, unknown fish, unknown 

plant: NR 1994 TX Agricultural Area Registered use Probable

I006010-002 Terrestrial plant Corn: unknown 1997 TX Agricultural area Misuse (accidental) Probable

I007269-001 Terrestrial plant Grape: NR 1998 CA Agricultural area Registered use Probable

I009556-005 Terrestrial plant Unknown Unknown NC Agricultural area Misuse (accidental) Possible

I009556-043 Terrestrial plant Potato: $4.4 million in damages 1992 CO Agricultural area Registered use Probable

I020592-001 Terrestrial plant Douglas fir: 80% of 80 acres 2008 WI Agricultural area Registered Use Possible

I021457-012 Terrestrial plant Pea: some 2006 WA Agricultural area Undetermined Unlikely

I021587-003 Terrestrial animal Honey bee: hives 2009 NJ Apiary Registered Use Possible

I000903-005 Terrestrial plant Unknown tree: NR 1991 TX Forest Misuse (accidental) Probable

I015217-001 Terrestrial plant Pasture grass: 8,000 sq ft 2004 OH Forest Registered use Probable

I016312-001 Terrestrial plant Ponderosa pine: 300 acres 2005 OR Forest Undetermined Possible

I005972-001 Terrestrial plant Live oak: 3 1997 TX Industrial site Registered Use Probable

I016429-001 Terrestrial plant Sweet corn: 10 acres; potato: 15 acres 2005 WA Industrial site Registered use Probable

I011666-001 Terrestrial plant

Sugar beet: 46,800 acres; garlic: 2 

acres; corn: unknown; potato: 

unknown; wheat: 10,700 acres; alfalfa: 

unknown, 800 acres

2000 ID Municipal operation Registered Use Highly 

Probable

B000601-001 Terrestrial plant Onion: 10 acres 1988 CA N/R Undetermined Possible

I000071-001 Terrestrial plant Peach: large numbers 1992 SC Peach Registered Use Possible

I016680-001 Terrestrial plant Grape: 13 acres 2005 OR Right-of-way Undetermined Possible

I013086-001 Terrestrial plant Sugar beet: unknown 2002 WA Right-of-way, rail Registered use Probable

I013194-001 Terrestrial plant Sugar beet: 10 acres 2002 ND Right-of-way, rail Registered use Probable

I020180-033 Terrestrial plant Brussels sprout: 9 acres 2008 CA Right-of-way, railroad Undetermined Possible

B000601-007 Terrestrial plant Sugar beet: NR 1985 NE Right-of-way, road Registered use Possible

I006010-001 Terrestrial plant Cotton: unknown 1997 LA Right-of-way, road Misuse (accidental) Probable

I014409-011 Terrestrial plant Onion: NR 1992 WA Right-of-way, road Registered use Possible

I015576-001 Terrestrial plant Sugar beet: NR 2004 OR Right-of-way, road Registered use Probable

I015832-001 Terrestrial plant Pecan: 1 2004 LA Right-of-way, road Registered use Probable

I016302-001 Terrestrial plant Grass, wheat: < 1 acre 2005 WA Right-of-way, road Registered use Probable

I015440-001 Terrestrial plant Corn, soybean: 1 acre 2003 MN Right-of-way, utility Misuse (accidental) Probable

I015796-001 Terrestrial plant Corn: 1-4 acres 2004 KY Right-of-way, utility Registered use Possible
31

Incident 

Number

Taxa Involved Magnitude Year State Use Legality2 Certainty

I015265-001 Terrestrial plant Pine: unknown 2004 TX Seedling Registered use Possible

I017481-001 Terrestrial plant Turf: unknown 2006 WI Turf, residential Undetermined Probable

I006010-003 Terrestrial plant, 

aquatic plant

Grass: unknown aquatic plant: 

unknown 1997 MS Utility plant Misuse (accidental) Probable

I020627-007 Terrestrial plant Ornamental: NR 2001 WA Wheat Undetermined Possible

I007269-002 Terrestrial plant Grass seed: NR 1998 TN YARD Registered use Probable

NR = not reported

1 ‘Minor’ incidents aggregately reported by the registrant(s) are not included in this table.

2 Incidents classified as ‘unrelated’ and ‘unlikely’ are excluded.
5. Exposure Pathways of Concern

The environmental fate properties of sulfometuron methyl indicate that spray drift, leaching to 

ground water, atmospheric deposition, and runoff represent potential transport mechanisms of 

sulfometuron methyl to aquatic and terrestrial organisms. Spray drift has been noted to be a 

special concern for many sulfonylurea herbicides because sensitive plants can be adversely 

affected by a small fraction of the applied amount. Drinking water and inhalation exposure 

pathways were screened using the SIP (Screening Imbibition Program, v1.0) and STIR 

(Screening Tool for Inhalation Risk, v1.0) screening methods. Results generated by SIP indicate 

that chronic exposure through drinking water alone is a potential concern for birds (see 

Appendix 3). However, there is some uncertainty associated with this result. Since a NOAEC

is not available for birds, chronic exposure to sulfometuron methyl through drinking water was 

characterized using chronic toxicity data for primisulfuron and flazasulfuron, sulfonylureas with 

a similar toxicity profile and the same mode of action as sulfometuron methyl. Results generated 

by STIR indicate exposure via inhalation was of low concern (no LOC exceedances are 

expected; see Appendix 4). SIP and STIR are described in detail at: 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm.

6. Analysis Plan

In order to address the risk hypothesis, the potential for adverse effects on the environment is 

estimated. The use, environmental fate, and ecological effects of sulfometuron methyl are 

characterized and integrated to assess the potential for risks. This is accomplished using a risk 

quotient (ratio of exposure concentration to effects concentration) approach (Appendix 6). 

Although risk is often defined as the likelihood and magnitude of adverse ecological effects, the 

risk quotient-based approach does not provide a quantitative estimate of likelihood and/or 

magnitude of an adverse effect. However, as outlined in the Overview Document (USEPA 

2004), the likelihood of effects to individual organisms from particular uses of sulfometuron 

methyl is estimated using the probit dose-response slope and either the level of concern 

(discussed below) or actual calculated risk quotient values.

This analysis plan will be revisited and may be revised depending upon the information 

submitted by the registrant and the public in response to the opening of the Registration Review 

docket for sulfometuron methyl.

6.1. Stressors of Concern

Ecological Risk Assessment

The stressor of concern for terrestrial and aquatic organisms is parent sulfometuron methyl. 
33

As previously stated in the section on degradate toxicity, the major degradates of sulfometuron 

methyl are several orders of magnitude less toxic than the parent sulfometuron methyl to 

terrestrial plants, and are therefore not expected to alter the risk picture. Furthermore, none of 

the degradates have been identified as chemicals of concern based on the conclusions of the EPA 

Health Effects Division Metabolism Committee Meeting (D200158, March 29, 1994). 

Therefore, EFED does not expect any of these degradates to be toxic to mammals or birds. 

Drinking Water 

A new drinking water assessment will be conducted to support future human health dietary risk 

assessments of sulfometuron methyl and will consider all currently registered uses of 

sulfometuron methyl. The new drinking water assessment will incorporate model estimates as 

well as available monitoring data of sulfometuron methyl and any transformation products of 

toxicological concern that might be identified by the Health Effects Division in surface water and 

groundwater. The potential toxicity of sulfometuron methyl transformation products will be 

considered in the drinking water assessment conducted during the Registration Review process. 

The final determination of the residues of concern will be made through consultation with the 

Health Effects Division (HED) and through any proceedings of the ROCKS (Residues of 

Concern Knowledge Subcommittee). 

6.2. Measures of Exposure 

In order to estimate risks of sulfometuron methyl exposure to aquatic and terrestrial organisms, 

all exposure modeling and resulting risk conclusions will be made based on maximum 

application rates, application methods, and any mitigation measures specifically indicated on the 

label. The models that will be used to predict the estimated environmental concentrations (EECs) 

of sulfometuron methyl are discussed on OPP’s water model website.16 These models include: 

PRZM (Pesticide Root Zone Model) and EXAMS (EXposure Analysis Modeling System), 

PRZM-groundwater (GW), T-REX, TerrPlant, STIR (Screening Tool for Inhalation Risk) and 

SIP (Screening Imbibition Program). Results of the SIP and STIR model runs are presented in 

Appendix 4 and 5, respectively.

6.3. Measures of Effect 

Toxicity data presented in Section 3 of this problem formulation will be used to calculate risk 

quotients. Any additional information submitted by the registrant or found in the open literature 

prior to conduct of the risk assessment, will also be considered. The open literature studies are 

identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007c), 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 pesticides on biotic communities from loss of species that are sensitive to the 

chemicals and from changes in structure and functional characteristics of the affected 

communities.

 16 http://www.epa.gov/opp00001/science/models_pg.htm
34

6.4. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to federally listed, threatened and/or endangered species from 

registered uses of pesticides in Registration Review. These assessments will be conducted in 

accordance with standard EPA procedures and good scientific judgment. The process for 

evaluating potential risks to listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm.

6.5. Endocrine Disruptor Screening Program

Sulfometuron methyl was not included in the first group of 67 chemicals issued an order to 

conduct Tier 1 EDSP testing. For additional information the EDSP program, visit 

http://www.epa.gov/endo/. 

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.

7. Preliminary Identification of Data Gaps

Table 8 and Table 9 identify environmental fate and eco-toxicological studies, respectively, that 

offer data for each guideline requirement, as well as study classifications and whether or not 

further data are needed in order to support risk assessment.

In addition to providing the guideline number and study title for required data, the DCI table 

provides a rationale for requiring the data, an explanation of how the data will be used, and a 

brief description of the how the data could impact the Agency’s future decision-making.

Before the status and needs of environmental fate and ecotoxicological studies are presented, 

additional information related to sulfometuron methyl labels is needed. The maximum number 

of applications and minimum time interval between applications are not specified for many uses 

on current sulfometuron methyl labels. The labels should express these aspects of sulfometuron 
35

methyl precisely or provide a rationale as to while, in some cases these aspects of application 

cannot be exactly specified (but with the maximum seasonal rates still clearly specified).

Environmental Fate Data Requirements

The Agency has completed a review of all available data submitted by the registrant as part of 

Registration Review. The following is required:

Guideline 835.6100 Terrestrial Field Dissipation Study – (Supporting Environmental 

Chemistry Methods (ECMs)/Independent Laboratory Validation (ILV): Sulfometuron 

methyl): State of the art ECMs in soil and water and ILVs used in sulfometuron methyl 

environmental fate studies are requested at this time17. Environmental chemistry methods for 

soil and water are only available for parent sulfometuron methyl. In addition, no ILVs have been 

submitted to the Agency with the exception of the immunoassay method which does not detect 

sulfometuron methyl with full specificity. Therefore, ECMs should be submitted with their 

associated ILVs for parent sulfometuron methyl and its major degradates sulfometuron

pyrimidine amine (IN-X0993), sulfometuron sulfonamide (IN-D5803), and saccharin (IN-581) in 

water and soil. 

Guideline 835.4100 Aerobic soil metabolism: Guideline requirements are partially fulfilled. 

The studies submitted to fulfill environmental fate data requirements for sulfometuron-methyl 

are not complete by current standards as stipulated in 40 CFR part 158 Subpart N §158.1300 for 

all pesticides with use patterns for aquatic food and nonfood applications: There are acceptable 

data from only one soil for aerobic soil metabolism under guideline #835.4100. The guideline 

stipulates that results from at least four relevant soils of different organic carbon content, pH, 

clay content, and with an active microbial biomass must be submitted in order to characterize the 

variability in the aerobic biodegradation of the pesticide in the environment. Therefore, studies 

must be conducted on three additional test soils.

The following studies have been submitted but are currently in review:

Guideline 835.1240 Adsorption / desorption (for degradates).

Guideline 835.6100 Forestry dissipation (required because of the forestry use of 

sulfometuron).

Table 8 lists the status of the fate and transport data requirements for sulfometuron methyl. The 

adequacy of the submitted data was evaluated relative to Agency guidelines. 

Table 8. Environmental Fate Data Requirements for Sulfometuron Methyl.

Guideline Data 

Requirement Test Material MRID

Study 

Classification

Data 

Requirement 

Met? 

More 

Data 

Needed? 

835.2120

[161-1] Hydrolysis Sulfometuron methyl 42715201 Acceptable Yes No

 17 The actual Field Dissipation studies have already been submitted and accepted.
36

Guideline Data 

Requirement Test Material MRID

Study 

Classification

Data 

Requirement 

Met? 

More 

Data 

Needed? 

835.2240

[161-2]

Direct photolysis 

in water

Sulfometuron 

methyl

42182401

43174101

41672812

Acceptable

Acceptable

Supplemental 18

Yes No

835.2410

[161-3] Photolysis on soil Sulfometuron methyl 41420601 Acceptable Yes No

None

[161-4]

Photodegradation 

in Air NA NA Waived19 NA NA

835.4100

[162-1] Aerobic soil 

metabolism

Sulfometuron 

methyl 42091401

Acceptable

but 

incomplete20

Partially Yes

835.4100

[162-1]

Aerobic soil 

metabolism

Sulfometuron 

methyl

43174102 

and 

00245375

Acceptable13 Partially Yes

835.4200

[162-2]

Anaerobic Soil 

Metabolism NA NA ref 162-3 Yes No

835.4200

[162-3]

Anaerobic aquatic 

metabolism

Sulfometuron 

methyl

42091402 

and 

43188601

Acceptable Yes No

835.4200

[162-3]

Anaerobic aquatic 

metabolism

Sulfometuron 

methyl

4413010-20 

(143540) Acceptable Yes No

835.4300

[162-4]

Aerobic aquatic 

metabolism

Sulfometuron 

methyl

42091403 

and 

43174103

Acceptable Yes No

835.1240

[163-1]

Adsorption/

Desorption

Sulfometuron 

methyl 42789301 Acceptable Yes No

835.1240

[163-1]

Adsorption/

Desorption

(degradates)

Pyrimidine 

amine

degradate

42789301 In Review21 --- ---

Saccharin

degradate 42789301 In Review --- ---

Sulfonamide 

degradate 42789301 In Review --- ---

None

[163-2]

Laboratory 

Volatility NA NA Waived22 NA NA

None

[163-3] Field Volatility NA NA Waived NA NA

835.6100

[164-1]

(also see 

Terrestrial Field

Dissipation

Sulfometuron 

methyl

43212101 

and 

43637101

Acceptable Yes No

 18 The initial photolysis study submitted was classified as supplemental; a replacement study was submitted and 

accepted to fully meet the 835.2240 data requirements.

19 Data requirement was waived based on sulfometuron-methyl’s low vapor pressure and Henry’s Law Constant. 20 Current guidelines require aerobic soil metabolism studies (Guideline 835.4100) in four test soils. The submitted 

studies are all only for one test soil and differ in the position of the radiolabel on the applied sulfometuron methyl. 21 Adsorption / desorption studies were submitted for three sulfometuron methyl degradates – initial review indicates 

that these studies may have deficiencies and in Registration Review it will be determined whether additional data 

should be required to further understand the sorption characteristics of the degradates.

22 Data requirement was waived based on sulfometuron-methyl’s low vapor pressure and Henry’s Law Constant.
37

Guideline Data 

Requirement Test Material MRID

Study 

Classification

Data 

Requirement 

Met? 

More 

Data 

Needed? 

below)

835.6100 

and 

835.6300

(Supporting)

Environmental

Chemistry 

Methods in soil 

and water; 

Independent Lab. 

Validation

Sulfometuron 

methyl + 

degradates?

44035201; 

43505001; 

43505002; 

43764801

Partial;(degrad

ate methods 

needed along 

with updated 

parent 

methods)

No Yes

835.6200

[164-2]

Aquatic Field 

Dissipation No study NA NA NA NA

835.6300

[164-3]

(also see 

above

Forestry 

Dissipation

Sulfometuron 

methyl

42091404 

and 

43174104

In review23 --- ---

850.1730

[165-4]

Accumulation in 

Fish Waived

41418623

and

146279

NA NA NA

835.7100

[166-1]

Ground Water 

Monitoring (small 

scale prospective)

---

N/A NA NA No

[165-5]

Accumulation in 

aquatic non-target 

organism 

(crayfish)

Waived NA NA NA NA

NA = not applicable

* Only an Independent Laboratory Validation for the immunoassay method has been conducted, this method is not 

specific enough to fulfill the data requirement).

Ecological Effects Data Requirements

Although a number of data gaps for ecological effects data requirements have been identified for 

sulfometuron methyl, we are not requiring additional data; analysis is provided below.

Guideline 850.1025 – Acute toxicity estuarine/marine invertebrate (bivalve); Guideline 

850.1035 – Acute toxicity estuarine/marine invertebrate (mysid); Guideline 850.1075 –

Acute toxicity estuarine/marine fish: Acceptable acute toxicity data for an estuarine/marine 

bivalve, mysid, and fish are not available. Submitted studies for these data requirements with a 

48-hr IC50 > 38.2 mg a.i./L (MRID 41672805), a 48-hr LC50 > 44.8 mg a.i./L (MRID 41672803), 

and a 48-hr LC50 > 45 mg a.i./L (MRID 41672804), respectively, are classified as supplemental 

due to high variability in measured test concentrations and uncertainty in exposure to dissolved 

sulfometuron methyl (i.e., test samples were not centrifuged prior to analysis). Although these 

 23 Data were submitted for the field dissipation of sulfometuron applied on forestry sites in a Gainesville, FL sand 

and a Scooba, MS silty clay loam and will be assessed to meet the requirements to meet field dissipation study 

requirements for this major use of sulfometuron methyl.
38

deficiencies could have rendered the study classifications as invalid, the studies are considered to 

provide some useful information for the Registration Review ecological 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 predicted EECs (i.e., a maximum peak concentration of 0.0315 mg/L in 

water, see Table 5), the bioavailable (dissolved) portion sulfometuron methyl would have to be 

approximately 1200-1400 fold lower than the highest measured test concentrations (~ 38-45 

mg/L) for risks to be evident. Therefore, repeating these studies would not likely affect the risk 

assessment conclusions, and new studies are not required. 

 

Guideline 850.1350 – Estuarine/marine invertebrate life cycle: Aquatic invertebrate life cycle 

toxicity data for an estuarine/marine invertebrate are required under 40 CFR Part 158 if the 

product is expected to enter the environment in significant concentrations because of its expected 

use or mobility patterns. No studies have been submitted for this data requirement. Given that 

the acute toxicity of sulfometuron methyl to aquatic animals is very low (slightly to practically 

non-toxic), the NOEC for the freshwater invertebrate life cycle study (MRID 41672806) was set 

at the highest test concentration, and there is no evidence to indicate that estuarine/marine 

animals are substantially more sensitive to sulfometuron methyl than freshwater animals, 

fulfilling this data requirement has a low potential to add value to the Registration Review risk 

assessment. In the absence of this data, toxicity to estuarine/marine invertebrates from chronic 

exposure to sulfometuron methyl will be characterized using toxicity data for freshwater 

invertebrates. New study is not required.

Guideline 850.1400 – Estuarine/marine and freshwater fish early-life stage: Early-life stage 

toxicity data for a freshwater fish are required under 40 CFR Part 158. Early-life stage toxicity 

data for an estuarine/marine fish are required under 40 CFR Part 158 if the product is expected to 

enter the environment in significant concentrations because of its expected use or mobility 

patterns. No studies have been submitted for this data requirement. Given that the acute toxicity 

of sulfometuron methyl to aquatic animals is very low (slightly to practically non-toxic), the 

NOEC for the freshwater invertebrate life cycle study (MRID 41672806) was set at the highest 

test concentration, and there is no evidence to indicate that estuarine/marine animals are 

substantially more sensitive to sulfometuron methyl than freshwater animals, fulfilling these data 

requirements has a low potential to add value to the Registration Review risk assessment. In the 

absence of this data, toxicity to freshwater fish from chronic exposure to sulfometuron methyl 

will be estimated using a freshwater fish ACR for another sulfonylurea with a similar toxicity 

profile and the same mode of action (e.g., flazasulfuron, PC code 119011; see 2008 RED, 

USEPA, 2008) to extrapolate from existing acute toxicity data for freshwater fish. For 

estuarine/marine fish, a similar approach may be taken. A new study is not required.

 

Guideline 850.2100 – Avian oral toxicity, passerine species: Acute oral toxicity data for a 

passerine species are required under the new 40 CFR Part 158. No studies have been submitted 

for this data requirement. The acute toxicity of sulfometuron methyl to birds and mammals is 

very low (practically non-toxic). In addition, acute toxicity data for a passerine species is 

available for flazasulfuron (PC code 119011), a sulfonylurea with a similar toxicity profile and 

the same mode of action as sulfometuron methyl. This study (MRID 47939912) indicates that 

flazasulfuron is practically non-toxic to the zebra finch (Taeniopygia guttata) on an acute oral 

basis (LD50 > 2000 mg a.i./kg-bw). Therefore, fulfilling this data requirement has a low 
39

potential to add value to the Registration Review risk assessment. In the absence of this data, 

toxicity to passerines from acute exposure to sulfometuron methyl will be characterized using all 

acute toxicity data for other sulfonylureas with a similar toxicity profile and the same mode of 

action that are available at the time of the Registration Review risk assessment. A passerine acute 

study with SMM is not required.

Guideline 850.2300 – Avian reproduction, upland game and waterfowl species: Avian 

reproductive toxicity data for water fowl and upland game species are required under 40 CFR 

Part 158. No studies have been submitted for this data requirement. The acute toxicity of 

sulfometuron methyl to birds and mammals is very low (practically non-toxic). In addition, there 

is ample avian reproductive toxicity data available for other sulfonylureas with a similar toxicity 

profile and the same mode of action (e.g., halosulfuron, PC code 128721, NOAEC = 1010 mg 

a.i./kg-diet, MRIDs 47792801 and 47792802; primisulfuron, PC code 128973, NOAEC = 500 

mg a.i./kg-diet, MRID 40512004; rimsulfuron, PC code 129009, NOAEC = 1250 ppm, 

D358867, D358872; flazasulfuron, PC code 119011, NOAEC = 484 mg a.i./kg-diet, MRID 

46220975). Avian reproductive NOECs for these sulfonylureas are 1 to 2 orders of magnitude 

greater than the peak sulfometuron methyl EEC of 90 mg/kg-diet (for birds consuming short 

grass) as calculated for the 2008 ecological risk assessment for the reregistration of sulfometuron 

methyl (USEPA, 2008) suggesting there is little concern for risk to birds from chronic exposure 

to sulfometuron methyl. Therefore, fulfilling this data requirement has a low potential to add 

value to the Registration Review risk assessment. In the absence of this data, toxicity to birds 

from chronic exposure to sulfometuron methyl will be characterized using chronic toxicity data

for other sulfonylureas with a similar toxicity profile and the same mode of action. New studies 

are not required.

Non-Guideline – Special study for non-target plant reproductive toxicity with TEP: A DCI 

for this study, previously published as a result of the 2008 RED for sulfometuron methyl, has not 

been fulfilled. EFED's Plant Technical Team (PTT) conducted an analysis of available SU plant 

reproduction data from the open literature and the registrant-submitted data for chlorsulfuron and 

concluded that data from the 850.4150 vegetative vigor guideline study are sufficiently 

protective of potential impacts to plant reproduction. Acetolactate synthase (ALS) inhibitors 

primarily affect metabolically-active meristem tissues. When plants are exposed at a young, 

vigorously growing life-stage, effects are expressed primarily as inhibition of vegetative growth 

(i.e. biomass, shoot length). As plants mature these effects are less pronounced. However, as 

plants enter their reproductive life-stage, the metabolically-active tissue will include flower and 

seed production. Plants exposed to SU herbicides during the reproductive life stage are likely to 

exhibit adverse effects on reproduction, generally expressed as reduced seed number or reduced 

seed weight. Based on the latest data analysis, these effects are expected to occur at similar 

concentrations to those effects determined in the guideline vegetative vigor studies (850.4150). 

Therefore, fulfilling this DCI has a low potential to add value to the Registration Review risk 

assessment, and a study is not required.
40

Table 9 provides ecological effects studies by MRID that offer data to fulfill each guideline 

requirement as well as indicates whether or not further data are needed in order to support the 

Registration Review ecological risk assessment (i.e., whether there is a data gap). 

Table 9. Ecological Effects Data Requirements for Sulfometuron Methyl and Remaining 

Data Gaps.

Guideline Data Requirement Test 

Substance

MRID/ 

Citation

Study 

Classification

Data Requirement 

Met?

More 

Data 

Needed?

850.1010

Acute toxicity 

freshwater 

invertebrates

99.6% 43501803 Acceptable Yes No

850.1025

850.1055

Acute toxicity

estuarine/marine 

invertebrate 

(bivalve)

99.1% 41672805 Supplemental No No1

850.1035

850.1045

Acute toxicity

estuarine/marine 

invertebrate 

(crustacean)

99.1% 41672804 Supplemental No No1

850.1075

Acute toxicity 

freshwater fish 

(cold water species)

99.6% 43501802 Acceptable Yes No

Acute toxicity 

freshwater fish 

(warm water species)

99.6% 43501801 Acceptable Yes No

Acute toxicity

estuarine/marine fish 99.1% 41672803 Supplemental No No1

850.1300

Aquatic invertebrate

life cycle

(freshwater)

99.1% 41672806 Acceptable Yes No

850.1350

Aquatic invertebrate 

life cycle 

(saltwater)

No data No No1

850.1400

Fish early-life stage

(freshwater) No data No No1

Fish early-life stage

(saltwater) No data No No1

850.2100

Avian oral toxicity 

(upland game or 

waterfowl species)

93% 00078700 Acceptable Yes

No

Avian oral toxicity

(passerine species) No data No No1

850.2200

Avian dietary toxicity 

(upland game species) 92.5% 00088813 Acceptable Yes No

Avian dietary toxicity 

(waterfowl species) 92% 00071414 Acceptable Yes No

850.2300

Avian reproduction 

(upland game species) No data No

No

 No1

 No1 Avian reproduction 

(waterfowl species) No data

850.3020 Honeybee acute 

contact toxicity 99.8% 41672810 Acceptable Yes No
41

Guideline Data Requirement Test 

Substance

MRID/ 

Citation

Study 

Classification

Data Requirement 

Met?

More 

Data 

Needed?

850.4100 Seedling emergence 

95.72% 

TEP 43538501 Acceptable Yes No

850.4150 Vegetative vigor 95.72% 

TEP 43538501 Acceptable Yes No

NonguidelineTerrestrial plant 

reproduction toxicity No data No No1

850.4400 Aquatic plant growth: 

Vascular 85.72% 43538503 Acceptable Yes No1

850.5400 Aquatic plant growth: 

Non-vascular

99.1%

99.16%

41680102

43538502 Acceptable Yes No1

1 Additional data are not required. See below for analysis.
42

APPENDIX 1. Submitted Environmental Fate and Effects 

Studies

Environmental Fate Studies

Guideline: 161-1 Hydrolysis

-------------------------------------------------------------------------------------

MRID: 71419

Harvey, J., Jr.; Bennett, C.T.; Reiser, R.W. (19??) Hydrolysis of ^14IC-DPX-5648. 

(Unpublished study received Jan 23, 1981 under 352-EX-107; submitted by E.I. du Pont de 

Nemours & Co., Wilmington, Del.; CDL:244195-U) 

MRID: 71420

Harvey, J., Jr.; Bennett, C.T.; Reiser, R.W. (1980?) Photolysis of ^14IC-DPX-5648: Document 

No. AMR-01-81. (Unpublished study received Jan 23, 1981 under 352-EX-107; submitted by 

E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:244195-V) 

MRID: 41418623

Harvey, J.; Dulka, J.; Anderson, J. (1985) Properties of Sulfometuron methyl affecting its 

environmental fate: aqueous hydrolysis and photolysis, mobility and adsorption on soils and 

bioaccumulation potential. Journal of Agricultural Food Chemistry. 33: 590-596. 

MRID: 41672811

Brattsen, L. (1987) Hydrolysis of ?Pyrimidine-2-C14| Sulfometuron Methyl: Lab Project 

Number: AMR-541-86. Unpublished study pre- pared by E. I. du Pont de Nemours and Co. 40 

p. 

MRID: 42715201

Schneiders, G. (1993) Hydrolysis of (Phenyl-carbon 14 (U)) and (Pyrimidine-2-carbon 

14))Sulfometuron Methyl in Buffer Solutions of pH 5, 7, and 9: Lab Project Number: AMR 

2426-92. Unpublished study prepared by E.I. du Pont de Nemours & Co. 48 p. 

MRID: 93206022

Harvey, J. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00071419. 

Hydrolysis of Sulfometuron Methyl: AMR 2-81,AMR-1819-90. Prepared by E.I. DU PONT DE 

NEMOURS CO. INC. 11 p. 

Guideline: 161-2 Photodegradation-water

-------------------------------------------------------------------------------------

MRID: 41418623

Harvey, J.; Dulka, J.; Anderson, J. (1985) Properties of Sulfome- turon methyl affecting its 

environmental fate: aqueous hydrolysis and photolysis, mobility and adsorption on soils and 

bioaccumulation potential. Journal of Agricultural Food Chemistry. 33: 590-596. 

MRID: 41672812
43

Naidu, M. (1990) Aqueous Photolysis of (Pyrimidine-2-C14) Sulfometuron Methyl: Lab Project 

Number: AMR-564-86. Unpublished study prepared by E. I. Du Pont de Nemours and Co. 43 p. 

MRID: 42182401

Schneiders, G.; Bachmura, S. (1992) Photodegradation of Phenyl-Carbon 14(U) and 

?Pyrimidine-2-carbon 14| Sulfometuron Methyl in Water--Conducted in Simulated Sunlight: Lab 

Project Number: AMR 2179-91. Unpublished study prepared by E.I. du Pont de Nemours and 

Co. 48 p. 

MRID: 43174101

Schneiders, G. (1994) Photodegradation of (Phenyl-(carbon 14)(U)) and (Pyrimidine-2-(carbon 

14)) Sulfometuron Methyl in Water Conducted in Simulated Sunlight: Supplement: Lab Project 

Number: AMR 2179-91. Unpublished study prepared by DuPont Agricultural Products. 18 p. 

Guideline: 161-3 Photodegradation-soil

-------------------------------------------------------------------------------------

MRID: 137864

Hardesty, P. (1983) Soil Photolysis of Sulfometuron Methyl: Docu- ment No. AMR-123-83. 

(Unpublished study received Apr 12, 1984 under 352-401; submitted by E.I. du Pont de 

Nemours & Co., Inc., Wilmington, DE; CDL:252941-C) 

MRID: 41420601

Ryan, D.; Atkins, B. (1986) Photodegradation of ?Phenyl(U)-Carbon 14|Sulfometruron Methyl 

and ?Pyrimidine-2-Carbon 14|Sulfometuron Methyl on Soil: Lab Project Number: AMR-573-86. 

Unpublished study prepared by E. I. du Pont de Nemours and Co. 35 p. 

MRID: 41680103

Ryan, D.; Atkins, B. (1986) Aged Soil Column Leaching Study with ?Phenyl(U)-carbon 

14|Sulfometuron Methyl and Pyrimidine-2-?car- bon 14|Sulfometuron methyl: Lab Project 

Number: AMR/643/86. Un- published study prepared by E. I. du Pont de Nemours & Co. 35 p. 

MRID: 42385707

Ryan, D.; Atkins, B. (1987) Photodegradation of ?Phenyl(U)-?carbon 14||-Sulfometuron Methyl 

and ?Pyrimidine-2-?carbon 14||-Sulfometuron Methyl on Soil: Supplement No. 1: Lab Project 

Number: AMR 573-86. Unpub- lished study prepared by E. I. du Pont de Nemours and Co. 15 

p. 

MRID: 93206023

Cadwgan, G. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 41420601. 

Photodegradation of Sulfometuron Methyl on Soil: du Pont Report No. AMR-573-86, AMR1861-90. Prepared by E.I. DU PONT DE NEMOURS CO. INC. 12 p. 

Guideline: 162-1 Aerobic soil metabolism

-------------------------------------------------------------------------------------
44

MRID: 78701

Anderson, J.J. (1980) Microbial Metabolism of ^14IC-Phenyl Labeled DPX-5648 in a Viable 

Soil Ecosystem: Document No. AMR-34-81. (Unpublished study received Jun 17, 1981 under 

352-EX-108; sub- mitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL: 245375-

B) 

MRID: 42091401

Monson, K.; Hoffman, D. (1990) Aerobic Soil Metabolism of ?Pyrimid- ine-2-Carbon 

14|Sulfometuron: Methyl in Keyport Silt Loam: Lab Project Number: AMR-1113-88. 

Unpublished study prepared by E.I. du Pont de Nemours and Co. 42 p. 

MRID: 43174102

Anderson, J. (1994) Microbial Metabolism of (carbon 14)-Phenyl-Labeled DPX-T5648 in a 

Viable Soil Ecosystem: Supplement: Lab Project Number: AMR 34-81. Unpublished study 

prepared by DuPont Agricultural Products. 7 p. 

MRID: 93206024

Anderson, J. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00078701. 

Microbial Metabolism of [Carbon 14]-Phenyl-Labeled DPX-T5648 in a Viable Soil Ecosystem: 

du Pont Report Nos. AMR 34-81, AMR-1846-90. Prepared by E.I. DU PONT DE NEMOURS 

CO. INC. 10 p. 

Guideline: 162-2 Anaerobic soil metabolism

-------------------------------------------------------------------------------------

MRID: 143540

Dulka, J.; Anderson, J. (1982) The Fate of [Carbon radiolabeled]- DPX-T5648 in an Anaerobic 

Environment. Unpublished study pre- pared by E. I. du Pont de Nemours and Co., Inc. 28 p. 

Guideline: 162-3 Anaerobic aquatic metab.

-------------------------------------------------------------------------------------

MRID: 78703

Anderson, J.J.; Dulka, J.J.; Harvey, J., Jr. (1981) Metabolism/ Environmental Fate Studies with 

^14IC-DPX-5648: Document No. AMR-35-81. Interim summary rept. (Unpublished study received 17, 1981 under 352-EX-108; submitted by E.I. du Pont de Nemours & Co., Wilmington, 

Del.; CDL:245375-D) 

MRID: 143540

Dulka, J.; Anderson, J. (1982) The Fate of [Carbon radiolabeled]- DPX-T5648 in an Anaerobic 

Environment. Unpublished study pre- pared by E. I. du Pont de Nemours and Co., Inc. 28 p. 

MRID: 42091402

Fallon, R. (1989) Anaerobic Aquatic Metabolism of (Pyrimidine-2- Carbon 14) Sulfometuron 

Methyl in Landenberg, Pennsylvania and Bradenton, Florida Pond Water and Sediment Systems: 
45

Lab Project Number: AMR 1084-88: 587-87. Unpublished study prepared by E.I. du Pont de 

Nemours and Co., Haskell Lab for Toxicology and Industrial Medicine. 64 p. 

MRID: 43188601

McCord, E. (1994) Anaerobic Aquatic Metabolism of (Pyrimidine-2-(carbon 14))Sulfometuron 

Methyl in Landenberg, Pennsylvania and Bradenton, Florida Pond Water and Sediment Systems: 

Supplement: Lab Project Number: AMR 1084-88: 587-87: 7831-001. Unpublished study 

prepared by Haskell Laboratory for Toxicology and Industrial Medicine, E.I. du Pont de 

Nemours and Co., Inc. 26 p. 

MRID: 93206025

Anderson, J. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00143540. The 

Fate of [Carbon 14]DPX-T5648 in an Anaerobic Environment: du Pont Report No. 65-82, AMR1848-90. Prepared by E.I. DU PONT DE NEMOURS CO. INC. 10 p. 

Guideline: 162-4 Aerobic aquatic metab.

-------------------------------------------------------------------------------------

MRID: 42091403

Rhodes, B. (1991) Aerobic Aquatic Metabolism of Carbon 14-Sulfometuron Methyl: Lab Project 

Number: AMR-1896-90. Unpublished study prepared by E.I. du Pont de Nemours and Co. 40 

p. 

MRID: 43174103

Rhodes, B. (1994) Aerobic Aquatic Metabolism of (Carbon 14)-Sulfometuron Methyl: 

Supplement: Lab Project Number: AMR 1896-90. Unpublished study prepared by DuPont 

Agricultural Products. 7 p. 

Guideline: 163-1 Leach/adsorp/desorption

-------------------------------------------------------------------------------------

MRID: 71423

Dulka, J.J.; Rapisarda, C.; Babineaux, B. (19??) Adsorption/Desorption Studies of (Carbon 14)-

Phenyl (UL)-Labeled DPX-5648 on Soil and Partitioning of DPX-5648 between Octanol and 

HI2^0 (KIow^): Document No. AMR-25-80. (Unpublished study received Jan 23, 1981 under 

352-EX-107; prepared in cooperation with Univ. of Delaware, College of Agricultural Sciences, 

submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:244195-Y) 

MRID: 78702

Dulka, J.J. (1981) Mobility of (Carbon 14)-Phenyl Labeled DPX-5648 in Soil; Soil Column 

Leaching Studies: AMR-11-81. (Unpublished study received Jun 17, 1981 under 352-EX-108; 

submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:245375-C) 

MRID: 78706

Dulka, J.J. (1980) Dissipation of ^14IC-DPX-5648 in the Field: Document No. AMR-35-81-C. 
46

Interim rept. (Unpublished study received Jun 17, 1981 under 352-EX-108; submitted by E.I. du 

Pont de Nemours & Co., Wilmington, Del.; CDL:245375-G) 

MRID: 41418623

Harvey, J.; Dulka, J.; Anderson, J. (1985) Properties of Sulfome- turon methyl affecting its 

environmental fate: aquous hydrolysis and photolysis, mobility and adsorption on soils and 

bioaccumu- lation potential. Journal of Agricultural Food Chemistry. 33: 590-596. 

MRID: 42789301

Kraut, G. (1993) Batch Equilibrium (Adsorption/Desorption) Study of (Phenyl(U)--(carbon 

14))Sulfometuron Methyl, IN-X993, IN-D5803, and Saccharin: Lab Project Number: AMR 

2607-93. Unpublished study prepared by E.I. duPont de Nemours and Co. 84 p. 

MRID: 93206026

Cadwgan, G. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00071423 and 

Related MRIDs 00078702. Soil Mobility of Sulfometuron Methyl: AMR-25-80,AMR-11-81. 

Prepared by E.I. DU PONT DE NEMOURS CO. INC. 12 p. 

Guideline: 163-2 Volatility - lab

-------------------------------------------------------------------------------------

MRID: 41418623

Harvey, J.; Dulka, J.; Anderson, J. (1985) Properties of Sulfome- turon methyl affecting its 

environmental fate: aquous hydrolysis and photolysis, mobility and adsorption on soils and 

bioaccumu- lation potential. Journal of Agricultural Food Chemistry. 33: 590-596. 

Guideline: 164-1 Terrestrial field dissipation

-------------------------------------------------------------------------------------

MRID: 78705

Anderson, J.J. (1980) Terrestrial Field Dissipation Study of ^14IC-DPX-5648 in Delaware, 

North Carolina, and Mississippi Soils: Document No. AMR-35-81-B. Interim rept. 

(Unpublished study received Jun 17, 1981 under 352-EX-108; submitted by E.I. du Pont de 

Nemours & Co., Wilmington, Del.; CDL:245375-F) 

MRID: 94840

Anderson, J.J. (1981) Terrestrial Field Dissipation Study of ^14IC- DPX-T5648 in Delaware, 

North Carolina, and Mississippi: Document No. AMR-59-81. (Unpublished study received Feb 

11, 1982 under 352-401; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.; 

CDL:246795-A) 

MRID: 43212101

Trubey, R. (1994) Field Soil Dissipation on Oust Herbicide: Sulfometuron Methyl: Lab Project 

Number: AMR/1922/91: DUPDE01B- 2. Unpublished study prepared by E.I. du Pont de 

Nemours and Co. and Alta Analytical Lab., Inc. 1151 p. 
47

MRID: 43253501

Wauchope, R.; Williams, R.; Marti, L. (1988) Runoff of Sulfometuron Methyl and Cyanazine 

from Small Plots: Effects of Formulation and Grass Cover. Journal of Environmental Quality 

19:119-125. 

MRID: 43637101

Trubey, R. (1995) Field Soil Dissipation of Oust Herbicide: Supplement No. 1 to Revision No. 1: 

Lab Project Number: AMR 1922-91: DUPDE01B-2. Unpublished study prepared by DuPont 

Agricultural Products and Alta Analytical Labs, Inc. 120 p. 

MRID: 93206027

Anderson, J. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00094840. 

Terrestrial Field Dissipation Study of [Carbon 14]-DPX-T5648 in Delaware, North Carolina, and 

Mississippi: du Pont Report No. AMR-59-81,AMR-1847-90. Prepared by E.I. DU PONT DE 

NEMOURS CO. INC. 10 p. 

Guideline: 164-3 Forest field dissipation

-------------------------------------------------------------------------------------

MRID: 42091404

Michael, J.; Neary, D. (1991) Movement of Sulfometuron Methyl in Forest Watersheds After 

Aerial Application of Oust for Herbaceous Weed Control (75% Dispersible Granule): Lab 

Project Number : AMR-1641-90. Unpublished study prepared by Auburn University Southern 

Forest Experiment Station. 172 p. 

MRID: 43174104

Trubey, R. (1994) Movement of Sulfometuron Methyl in Forest Watersheds After Aerial 

Application of Oust for Herbaceous Weed Control (75% Dispersible Granule): Lab Project 

Number: AMR 1641-90. Unpublished study prepared by Southern Forest Experiment Station, 

Auburn University and DuPont Agric. Products. 38 p. 

MRID: 43174105

Trubey, R.; Devine, P. (1994) Storage Stability of Sulfometuron Methyl in Soil (Frozen) and in 

Water (Frozen, Refrigerated, and Room Temperature): Lab Project Number: AMR 1586-90: 02-

9002. Unpublished study prepared by DuPont Agricultural Products and Minnesota Valley 

Testing Laboratories, Inc. 79 p. 

MRID: 43492501

Trubey, R. (1994) Movement of Sulfometuron Methyl in Forest Watersheds After Aerial 

Application of Oust for Herbaceous Weed Control (75 (percent) Dispersible Granule): 

Supplement No. 2: Lab Project Numbers: FS-SO-4105-1.19: AMR 1641-90. Unpublished study 

prepared by Auburn University. 143 p. 
48

Guideline: 165-1 Confined rotational crop

-------------------------------------------------------------------------------------

MRID: 47459401

Swanson, M. (1988) Confined Accumulation Study of [carbon 14]-Sulfometuron Methyl of 

Rotational Crops. Project Number: AMR/956/87. Unpublished study prepared by DuPont 

Experiment Station Laboratories. 42 p.

Guideline: 165-4 Bioaccumulation in fish

-------------------------------------------------------------------------------------

MRID: 146279

Harvey, J. (1981) Bioaccumulation Studies of [Carbonradiolabeled]- Phenyl-DPX-5648 in Fish. 

Unpublished study prepared by E. I. du Pont de Nemours and Co., Inc. 15 p. 

MRID: 41418623

Harvey, J.; Dulka, J.; Anderson, J. (1985) Properties of Sulfome- turon methyl affecting its 

environmental fate: aquous hydrolysis and photolysis, mobility and adsorption on soils and 

bioaccumu- lation potential. Journal of Agricultural Food Chemistry. 33: 590-596. 

MRID: 93206028

Harvey, J. (1990) E.I. du Pont De Nemours Co. Phase 3 Summary of MRID 00146279. 

Bioaccumulation of Sulfometuron Methyl in Fish: AMR-41-81,AMR-1820- 90. Prepared by E.I. 

DU PONT DE NEMOURS CO. INC. 11 p. 

Guideline: 171-4B Residue Analytical Methods

-------------------------------------------------------------------------------------

MRID: 44035201

Powley, C.; de Bernard, P. (1996) Analytical Method for the Determination of Azimsulfuron, 

Bensulfuron Methyl, Chlorimuron Ethyl, Ethametsulfuron Methyl, Sulfometuron Methyl, and 

Triflusulfuron Methyl in Water: Lab Project Number: AMR 3720-95. Unpublished study 

prepared by E. I. du Pont de Nemours and Co. 60 p. 

MRID: 71421

Citation: Anderson, J.J.; Berg, D.S. (1980?) Studies To Determine the Effect of DPX-5648 on 

Metabolic Processes of Soil Microbes: Document No. AMR-01-81. (Unpublished study 

received Jan 23, 1981 under 352-EX-107; prepared in cooperation with Univ. of Delaware, 

College of Agricultural Sciences, submitted by E.I. du Pont de Nemours & Co., Wilmington, 

Del.; CDL:244195-W) 

MRID: 71422

Citation: Hadley, B.A.; Bembry, R.P.; Larsen, J.M.; et al. (19??) The Effect of DPX-5648 on 

Soil Microorganism Populations. (Unpublished study received Jan 23, 1981 under 352-EX-107; 

prepared in co- operation with Univ. of Delaware, Soil Testing Laboratory, sub- mitted by E.I. 
49

du Pont de Nemours & Co., Wilmington, Del.; CDL:244195-X) 

MRID: 78704

Citation: Harvey, J., Jr. (1981) Aerobic Soil Metabolism of ?^14IC|-Phenyl- DPX-5648: 

Document No. AMR-35-81-A. Interim rept. (Unpublished study received Jun 17, 1981 under 

352-EX-108; submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:245375-E) 

MRID: 78707

Citation: Dulka, J.J. (1980) The Fate of ?^14IC|-DPX-5648 in an Anaerobic Environment: 

Document No. AMR-35-81-D. Interim rept. (Un- published study received Jun 17, 1981 under 

352-EX-108; submit- ted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL: 245375-

H) 

MRID: 78710

Citation: Harvey, J., Jr. (1981) Bioaccumulation Studies of ?^14IC|-Phenyl- DPX-5648 in Fish: 

Document No. AMR-35-81-F. Interim rept. (Unpublished study received Jun 17, 1981 under 

352-EX-108; sub- mitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL: 245375-

K) 

MRID: 137863

Citation: Harvey, J. (1981) Bioaccumulation Studies of 14C-Phenyl-DPX-5648 in Fish: 

Document No. AMR-41-81. (Unpublished study received Apr 12, 1984 under 352-401; 

submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, DE; CDL:252941-B) 

MRID: 43039601

Citation: Whitcomb, C. (1991) (Compilation Concerning the Use of Sulfonylurea-type 

Herbicides and the Fate and Effects in plants and the Environment). Unpublished study. 264 p. 
50

SUBMITTED EFFECTS STUDIES:

Guideline: 71-1 Avian Single Dose Oral Toxicity

-------------------------------------------------------------------------------------

MRID: 78700

Dudeck, S.H.; Bristol, K.L. (1981) Final Report: Single-dose Oral Toxicity in Mallard Ducks: 

Project No. 201-552. (Unpublished study received Jun 17, 1981 under 352-EX-108; prepared by 

Hazle- ton Laboratories America, Inc., submitted by E.I. du Pont de Nemours & Co., 

Wilmington, Del.; CDL:245375-A) 

Guideline: 71-2 Avian Dietary Toxicity

-------------------------------------------------------------------------------------

MRID: 71414

Dudeck, S.H.; Twigg, C.J. (1980) Final Report: Avian Dietary Toxic- ity (LC50) Study in 

Mallard Ducks: Project No. 201-548; HLO-788- 80. (Unpublished study received Jan 23, 1981 

under 352-EX-107; prepared by Hazleton Laboratories America, Inc., submitted by E.I. du Pont 

de Nemours & Co., Wilmington, Del.; CDL:244195-P) 

MRID: 71415

Dudeck, S.; Bristol, K.L. (1981) Final Report: Avian Dietary Toxic- ity Study in Bobwhite 

Quail: Project No. 201-549; HLO-17-81. (Unpublished study received Jan 23, 1981 under 352-

EX-107; pre- pared by Hazleton Laboratories America, Inc., submitted by E.I. du Pont de 

Nemours & Co., Wilmington, Del.; CDL:244195-Q) 

MRID: 88813

Fink, R.; Beavers, J.B.; Joiner, G.; et al. (1981) Final Report: Eight-day Dietary LCI50^--

Bobwhite Quail: H-13,647-03: Project No. 112-122. (Unpublished study received Dec 12, 1981 

under 352-401; prepared by Wildlife International, Ltd., submitted by E.I. du Pont de Nemours 

& Co., Inc., Wilmington, Del.; CDL: 246409-A) 

Guideline: 72-1 Acute Toxicity to Freshwater Fish

-------------------------------------------------------------------------------------

MRID: 71416

Muska, C.F.; Trivits, R.L. (1980) 96-hour LC50 to Rainbow Trout: Haskell Laboratory Report 

No. 630-80. (Unpublished study re- ceived Jan 23, 1981 under 352-EX-107; submitted by E.I. 

du Pont de Nemours & Co., Wilmington, Del.; CDL:244195-R)

MRID: 71417

Muska, C.F.; Hall, C.L. (1980) 96-hour LC50 to Bluegill Sunfish: Haskell Laboratory Report 

No. 629-80. (Unpublished study received Jan 23, 1981 under 352-EX-107; submitted by E.I. du 

Pont de Nemours & Co., Wilmington, Del.; CDL:244195-S) 

MRID: 143539

Driscoll, R. (1984) Early Life Stage Toxicity of INT-5648-18 to Fathead Minnow: Report No. 

765-82. Unpublished study prepared by Haskell Laboratory. 29 p. 
51

MRID: 43501801

Brown, M. (1994) Static, Acute, 96-Hour LC50 of DPX-T5648-42 (Sulfometuron Methyl) to 

Bluegill Sunfish, Lepomis macrochirus: (Limit Test): Lab Project Numbers: 9868-001: 590-94: 

HLR 590-94. Unpublished study prepared by E.I. du Pont de Nemours and Co. 27 p. 

MRID: 43501802

Brown, M. (1994) Static, Acute, 96-Hour LC50 of DPX-T5648-42 (Sulfometuron Methyl) to 

Rainbow Trout, Oncorhynchus mykiss: (Limit Test): Lab Project Numbers: 9868-001: 589-94: 

HLR 589-94. Unpublished study prepared by E.I. du Pont de Nemours and Co. 28 p. 

Guideline: 72-2 Acute Toxicity to Freshwater Invertebrates

-------------------------------------------------------------------------------------

MRID: 71418

Muska, C.F.; Trivits, R.L. (1980) 48-hour LC50 to Daphnia Magna: Haskell Laboratory Report 

No. 631-80. (Unpublished study re- ceived Jan 23, 1981 under 352-EX-107; submitted by E.I. 

du Pont de Nemours & Co., Wilmington, Del.; CDL:244195-T) 

MRID: 145514

Wetzel, J. (1984) 48-Hour EC50 to Daphnia Magna: Report No. 147- 84. Unpublished study 

prepared by Haskell Laboratory. 5 p. 

MRID: 43501803

Brown, M. (1994) Static, Acute, 96-Hour LC50 of DPX-T5648-42 (Sulfometuron Methyl) to 

Daphnia magna: (Limit Test): Lab Project Numbers: 9868-001: 588-94: HLR 588-94. 

Unpublished study prepared by E.I. du Pont de Nemours and Co. 26 p. 

Guideline: 72-3 Acute Toxicity to Estuarine/Marine Organisms

-------------------------------------------------------------------------------------

MRID: 41672803

Ward, T.; Boeri, R. (1990) Static Acute Toxicity of IN T5648-40 to the Sheepshead Minnow,

Cyprinodon variegatus: Lab Project Num- ber: 4581-804: 90108-DU. Unpublished study 

prepared by Resource Analysts, Inc. 32 p. 

MRID: 41672804

Ward, T.; Boeri, R. (1990) Static Acute Toxicity of IN 75648-40 to the Mysid, Mysidopsis 

bahia: Lab Project Number: 615-90: 90109- DU. Unpublished study prepared by Resource 

Analysts, Inc. 32 p. 

MRID: 41672805

Ward, T.; Boeri, R. (1990) Static Acute Toxicity of IN T5648-40 to Bivalve Mollusc Embryos 

and Larvae: Lab Project Number: 633-90: 90110-DU. Unpublished study prepared by Resource 

Analysts, Inc. 31 p. 
52

Guideline: 72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

-------------------------------------------------------------------------------------

MRID: 126600

Muska, C.; Driscoll, R. (1982) Early Life Stage Toxicity of Int- 5648-18 to Fathead Minnow: 

Haskell Laboratory Report No. 765-82. (Unpublished study received Mar 28, 1983 under 352-

401; submit- ted by E.I. du Pont de Nemours & Co., Inc., Wilmington, DE; CDL:249796-A) 

MRID: 143539

Driscoll, R. (1984) Early Life Stage Toxicity of INT-5648-18 to Fathead Minnow: Report No. 

765-82. Unpublished study prepared by Haskell Laboratory. 29 p. 

MRID: 41672806

Baer, K. (1990) Chronic Toxicity of IN T5648-40 to Daphnia magna: Lab Project Number: 614-

90: MR-4581-804. Unpublished study pre- pared by Haskell Laboratory. 260 p. 

Guideline: 122-1 Seed Germination/Seedline Emergence and Vegetable Vigor

-------------------------------------------------------------------------------------

MRID: 41672809

Drake, D. (1990) Tier Testing Evaluation of Sulfometuron Methyl on Plants Grown under 

Greenhouse: Lab Project Number: DCD-90-2. Unpublished study prepared by E. I. Du Pont de 

Nemours and Co. 13 p. 

MRID: 43538501

McKelvey, R. (1995) Influence of Sulfometuron Methyl (DPX-T5648) on Seedling Emergence 

and Vegetative Vigor of Several Terrestrial Plants: Lab Project Number: AMR 2871-93. 

Unpublished study prepared by DuPont Agricultural Products. 415 p. 

Guideline: 122-2 Aquatic plant growth

-------------------------------------------------------------------------------------

MRID: 41680102

Hoberg, J. (1990) Sulfometuron methyl-Toxicity to the Freshwater Green Alga Selenastrum 

capricornutum: Lab Project Number: AMR- 1893-90. Unpublished study prepared by 

Springborn Laboratories, Inc. 24 p. 

MRID: 43538502

Thompson, S. (1994) Sulfometuron Methyl (DPX-T5648): Influence on Growth and 

Reproduction of Three Select Algal Species: Lab Project Number: AMR 2892-93: 112A-121. 

Unpublished study prepared by Wildlife International and Haskell Lab for Toxicology and 

Industrial Medicine. 58 p. 

Guideline: 123-1 Seed germination/seedling emergence and vegetative vigor

-------------------------------------------------------------------------------------
53

MRID: 41672809

Drake, D. (1990) Tier Testing Evaluation of Sulfometuron Methyl on Plants Grown under 

Greenhouse: Lab Project Number: DCD-90-2. Unpublished study prepared by E. I. Du Pont de 

Nemours and Co. 13 p. 

MRID: 43228101

Cain, J. (1994) Letter Sent to Office of Pesticide Programs dated May 5, 1994: Report of 

supplementary study information: DuPont Sulfometuron Methyl, DuPont Oust Herbicide: 

(Terrestrial Tier II Non-target testing: plant studies: AMR 2871-93). Prepared by DuPont

Agricultural Products. 3 p. 

MRID: 43538501

McKelvey, R. (1995) Influence of Sulfometuron Methyl (DPX-T5648) on Seedling Emergence 

and Vegetative Vigor of Several Terrestrial Plants: Lab Project Number: AMR 2871-93. 

Unpublished study prepared by DuPont Agricultural Products. 415 p. 

Guideline: 123-2 Aquatic plant growth

-------------------------------------------------------------------------------------

MRID: 43538502

Thompson, S. (1994) Sulfometuron Methyl (DPX-T5648): Influence on Growth and

Reproduction of Three Select Algal Species: Lab Project Number: AMR 2892-93: 112A-121. 

Unpublished study prepared by Wildlife International and Haskell Lab for Toxicology and 

Industrial Medicine. 58 p. 

MRID: 43538503

Kannuck, R.; Sloman, T. (1995) Sulfometuron Methyl (DPX-T5648): Influence on Growth and 

Reproduction of Lemna gibba G3: Lab Project Number: AMR 2902-94. Unpublished study 

prepared by Stine-Haskell Research Center. 41 p. 

Guideline: 141-1 Honey bee acute contact

-------------------------------------------------------------------------------------

MRID: 41672810

Hoxter, K. ; Smith, G. (1990) An Acute Contact Toxicity Study with the Honey Bee: Lab Project 

Number: 112-243: 583-90. Unpublished study prepared by Wildlife International Ltd. 14 p. 

Analytical Methods

MRID: 43505001

Citation: Trubey, R.; Sund, R. (1994) An ELISA Immunoassay Method for the Determination of 

Residues of Sulfometuron Methyl in Soil and Water: Lab Project Number: AMR 3066-94. 

Unpublished study prepared by DuPont Agricultural Products. 116 p. 

MRID: 43505002
54

Citation: Trubey, R.; Bethem, R.; Peterson, B. (1994) An LC/MS Method for the Determination 

of Residues of Sulfometuron Methyl in Soil and Water: Lab Project Number: AMR 3164-94: 

13710. Unpublished study prepared by Alta Analytical Lab. 110 p. 

MRID: 43764801

Citation: Trubey, T.; Sund, R.; Hill, S. (1995) Analytical Method for the Determination of 

Residues of Sulfometuron Methyl in Soil and Water, Using Supercritical Fluid Extraction: Lab 

Project Number: AMR 2498-92. Unpublished study prepared by DuPont Ag Products. 72 p. 
55

APPENDIX 2: 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
56

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

Free acid Sulfonamide

FA-Sulfonamide; Free acid; IN-D5119

2-(Aminosulfonyl)benzoic acid

O

O

H

S

O

O

N

H

H
57

APPENDIX 3. Uncertainties Related to the Use of Incident 

Information from the Ecological Incident Information System

Incident data are used in risk assessments to provide evidence that the risk predictions from the 

screening level assessment are supported by actual effects in the field. Incident reports 

submitted to EPA since approximately 1994 have been tracked by assignment of incident 

numbers in an Incident Data System (IDS), microfiched, and then entered to a second database, 

the Ecological Incident Information System (EIIS). Additionally, there is an on-going effort to 

enter information to EIIS on incident reports received prior to establishment of current databases. 

Incident reports are not received in a consistent format (e.g., states and various labs usually have 

their own formats), may involve multiple incidents involving multiple chemicals in one report, 

and may report on only part of a given incident investigation (e.g., residues). 

Incidents entered into EIIS are categorized into one of several certainty levels regarding the 

likelihood that a particular pesticide is associated with the incident: highly probable, probable, 

possible, unlikely, or unrelated. In brief, “highly probable” incidents usually require carcass 

residues and/or clear circumstances regarding the exposure. “Probable” incidents include those 

where residues were not available and/or circumstances were less clear than for “highly 

probable.” “Possible” incidents include those where multiple chemicals may have been involved 

and it is not clear what the contribution was of a given chemical. The “unlikely” category is 

used, for example, where a given chemical is practically nontoxic to the category of organism 

killed and/or the chemical was tested for but not detected in samples. “Unrelated” incidents are 

those that have been confirmed to be not pesticide-related.

Incidents entered into the EIIS are also categorized as to use/misuse. Unless specifically 

confirmed by a state or federal agency to be misuse, or there was very clear misuse such as 

intentional baiting to kill wildlife, incidents are not typically considered misuse. 

The number of documented kills in EIIS is believed to be a small fraction of total mortality 

caused by pesticides. Mortality incidents must be seen, reported, investigated, and have 

investigation reports submitted to EPA to have the potential for entry into the database. 

Incidents often are not seen, due to scavenger removal of carcasses, decay in the field, or simply 

because carcasses may be hard to see on many sites and/or few people are systematically 

looking. Poisoned animals may also move off-site to less conspicuous areas before dying. 

Incidents may not get reported to appropriate authorities capable of investigating the incident for 

a variety of reasons including the finder may not know of the importance of reporting incidents, 

may not know who to call, may not feel they have the time or desire to call, or may hesitate to 

call because of their own involvement in the kill. Incidents reported may not get investigated if 

resources are limited or may not get investigated thoroughly, with residue analyses, for example. 

Also, if kills are not reported and investigated promptly, there will be little chance of 

documenting the cause, since tissues and residues may deteriorate quickly. Reports of 

investigated incidents often do not get submitted to EPA, since reporting by states is voluntary. 

Furthermore, the database relies heavily on registrant-submitted incident reports, and registrants 

are currently only required to submit detailed information on ‘major’ ecological incidents, while 

‘minor’ incidents are reported aggregately. 
58

Based on the 40 CFR (§159.184 Toxic or adverse effect incident reports), an ecological incident 

is considered ‘major’ if any of the following criteria are met:

Fish or wildlife:

(A) Involves any incident caused by a pesticide currently in Formal Review for 

ecological concerns. 

(B) Fish: Affected 1,000 or more individuals of a schooling species or 50 or more 

individuals of a non-schooling species. 

(C) Birds: Affected 200 or more individuals of a flocking species, or 50 or more 

individuals of a songbird species, or 5 or more individuals of a predatory species. 

(D) Mammals, reptiles, amphibians: Affected 50 or more individuals of a relatively 

common or herding species or 5 or more individuals of a rare or solitary species. 

(E) Involves effects to, or illegal pesticide treatment (misuse) of a substantial tract of 

habitat (greater than or equal to 10 acres, terrestrial or aquatic). 

Plants: 

(A) The effect is alleged to have occurred on more than 45 percent of the acreage 

exposed to the pesticide.

All other ecological incidents are considered ‘minor’ and only need to be aggregately reported. 

‘Minor’ incidents reported by the registrants are not included in the EIIS database. Therefore, 

for example, an incident could affect 900 fish, 150 birds, 45 mammals, and 40% of an exposed 

crop and not be included in the EIIS database [unless is it reported by a non-registrant (e.g., an 

incident submitted by a state agency – which are not systematically collected)]. Therefore, 

because the number of documented kills in EIIS is believed to be a small fraction of total 

mortality caused by pesticides, absence of reports does not necessarily provide evidence of an 

absence of incidents. 
59

APPENDIX 4. SIP v.1.0 Inputs and Outputs

SIP employs the following conservative assumptions to derive upper bound exposure 

estimates:

1) The chemical concentration in drinking water is at the solubility limit in water (at 25oC).

2) The assessed animals obtain 100% of their daily water needs through drinking water.

3) The daily water need is equivalent to the daily water flux rate as calculated by Nagy and 

Peterson (1988).

4) The body weight of the assessed bird is equivalent to the smallest generic bird modeled 

in T-REX (i.e., 20 g). This assumption results in the highest ratio of exposure to toxicity for 

the 3 assessed avian body weights of T-REX (i.e., 20, 100, 1000 g).

5) The body weight of the assessed mammal is equivalent to the largest generic mammal 

modeled in T-REX (i.e., 1000 g). This results in the highest ratio of exposure to toxicity for 

the 3 assessed mammalian body weights of T-REX (i.e., 15, 35, 1000 g). 

Table 1. Inputs

Parameter Value Data source

Chemical name Sulfometuron methyl

Solubility (in water at 25oC; mg/L) 244 2008 RED; USEPA, 2008

Mammalian LD50 (mg/kg-bw) 5000 MRID 43089201

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 300 MRID 00078798

Mammalian test species other

Body weight (g) of "other" mammalian species 3898

Avian LD50 (mg/kg-bw) 4650 MRID 00078700

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 500 For flazasulfuron, MRID 46220926

Bobwhite quail NOAEC (mg/kg-diet) 484 For primisulfuron, MRID 40512004

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird species

Body weight (g) of 2nd other avian species

Enter body weight of 'other' mammalian species for NOAEL.
60

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 41.9680 41.9680

Adjusted toxicity value (mg/kg-bw) 3845.8028 421.5331

Ratio of exposure to toxicity 0.0109 0.0996

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 197.6400 197.6400

Adjusted toxicity value (mg/kg-bw) 2414.3981 24.8063

Ratio of exposure to acute toxicity 0.0819 7.9673

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Exposure through 

drinking water alone is a 

potential concern for 

birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when aggregated with 

other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water may contribute to a total exposure that has 

potential for effects to non-target animals.
61

APPENDIX 5. STIR v.1.0 Inputs and Outputs

Welcome to the EFED 

Screening Tool for Inhalation Risk

This tool is designed to provide the risk assessor with a rapid method for determining the potential

significance of the inhalation exposure route to birds and mammals in a risk assessment.

Input Data Source

Application and Chemical Information

Enter Chemical Name Sulfometuron methyl

Enter Chemical Use non-crop

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 364.38 2008 RED, USEPA

Enter Chemical Vapor Pressure (mmHg) 5.40E-16 2008 RED, USEPA

Enter Application Rate (lb a.i./acre) 0.375 2008 RED, USEPA

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 4650 MRID 00078700

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000 MRID 43089201

Enter Lowest Rat Inhalation LC50 (mg/L) 5 MRID 43089203

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.06E-11

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 1.33E-12

Adjusted Inhalation LD50 1.87E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 7.12E-14

Exposure not Likely 

Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 3.60E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 1.93E-03

Exposure not Likely 

Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.06E-11

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 1.67E-12

Adjusted Inhalation LD50 2.98E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 5.62E-15

Exposure not Likely 

Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 4.53E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 1.52E-04

Exposure not Likely 

Significant
62

APPENDIX 6. The Risk Quotient Method and Levels of 

Concern

The Risk Quotient Method is the means used by EFED to integrate the results of exposure and 

ecotoxicity data. For this method, Risk Quotients (RQs) are calculated by dividing exposure 

estimates by the acute and chronic ecotoxicity values (i.e., RQ = EXPOSURE/TOXICITY). 

These RQs are then compared to OPP's levels of concern (LOCs). These LOCs are criteria used 

by OPP to indicate potential risk to non-target organisms and the need to consider regulatory 

action. EFED has defined LOCs for acute risk, potential restricted use classification, and for 

endangered species. 

The criteria indicate that a pesticide used as directed has the potential to cause adverse effects 

on non-target organisms. LOCs currently address the following risk presumption categories: 

(1) acute - there is a potential for acute risk; regulatory action may be warranted in addition to 

restricted use classification; 

(2) acute restricted use - the potential for acute risk is high, but this may be mitigated through 

restricted use classification;

(3) acute endangered species - the potential for acute risk to endangered species is high, 

regulatory action may be warranted; and 

(4) chronic risk - the potential for chronic risk is high, regulatory action may be warranted. 

Currently, EFED does not perform assessments for chronic risk to plants, acute or chronic 

risks to non-target insects, or chronic risk from granular/bait formulations to mammalian or 

avian species. 

The ecotoxicity test values (i.e., measurement endpoints) used in the acute and chronic RQs are 

derived from required studies. Examples of ecotoxicity values derived from short-term 

laboratory studies that assess acute effects are: (1) LC50 (fish and birds), (2) LD50 (birds and 

mammals), (3) EC50 (aquatic plants and aquatic invertebrates), and (4) EC25 (terrestrial 

plants). Examples of toxicity test effect levels derived from the results of long-term laboratory 

studies that assess chronic effects are: (1) the Lowest Observed Adverse Effect Concentration 

(LOAEC) (birds, fish, and aquatic invertebrates), and (2) the No Observed Adverse Effect 

Concentration (NOAEC) (birds, fish and aquatic invertebrates). The NOAEC is generally used 

as the ecotoxicity test value in assessing chronic effects. Risk presumptions, along with the 

corresponding RQs and LOCs are summarized in Table B1.
63

Table B1. Agency risk quotient (RQ) metrics and levels of concern (LOC) per risk class.

Risk Class Risk Description RQ LOC

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures

Peak EEC/LC501 0.5

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use 

classification

Peak EEC/LC501 0.1

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

Peak EEC/LC501 0.05

Chronic Potential for effects to non-listed and listed animals 

from chronic exposures 

60-day EEC/NOEC (fish) 1

21-day EEC/NOEC 

(invertebrates)

Terrestrial Animals (mammals and birds)

Acute Potential for effects to non-listed animals from acute 

exposures

EEC2/LC50 (Dietary) 0.5

EEC/LD50 (Dose)

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use 

classification

EEC2

/LC50 (Dietary) 0.2

EEC/LD50 (Dose)

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

EEC 2/LC50 (Dietary) 0.1

EEC/LD50 (Dose)

Chronic Potential for effects to non-listed and listed animals 

from chronic exposures

EEC 2/NOAEC 1

Plants

Non-Listed Potential for effects to non-target, non-listed plants 

from exposures

EEC/ EC25 1

Listed Plant Potential for effects to non-target, listed plants from 

exposures

EEC/ NOEC 1

EEC/ EC05

1 LC50 or EC50. 2 Based on upper bound Kenaga values.
64

APPENDIX 7. Toxicity Endpoints for Sulfometuron Methyl 

and its Degradates and Analogues

Detailed summaries of measured and modeled endpoints for sulfometuron methyl and its

degradates and related compounds are presented in Tables 10 to 13.

Table 10. Summary of Toxicity Endpoints for Saccharin

Taxonomic 

Group

Study 

Type

Species Toxicity Value & Acute 

Toxicity Classification

Source

Freshwater 

fish

Acute

Rainbow trout

(Oncorhynchus 

mykiss)

96-hr LC50 > 124 mg/L

Practically non-toxic

MRID 48518912

In review

Chronic N/A Chronic value* = 2.4 mg/L ECOSAR: Class amides

Freshwater 

invertebrates

Acute Water flea

(Daphnia magna)

48-hr EC50 > 118 mg/L

Practically non-toxic

MRID 48518911

In review

Chronic N/A Chronic value* = 1.7 mg/L ECOSAR: Class amides

Aquatic 

plants

Vascular Duckweed

(Lemna gibba)

14-day EC50 = 5.5 mg/L

14-day NOEC < 0.63 mg/L

MRIDs 48518909 and 45791505

In review

Nonvascular

Green alga

(Selenastrum 

capricornutum)

72-hr EC50 > 10 mg/L MRID 48518910

In review

Green algae Chronic value* = 3.4 mg/L ECOSAR: Class thiazolinones 

(iso-) 

Mammals Acute 

oral Rat LD50 > 142,000 mg/kg-bwPractically non-toxic PPBD data1

* duration associated with the reported chronic value was not reported by the ECOSAR program 1 Toxicity data were retrieved from PPDB through a search using the CAS number for saccharin, 81-07-2. The 

Pesticide Properties Database (aka. Footprint) may be accessed at: 

http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

Table 11. ECOSAR-predicted Toxicity Values for Four Major Degradates of Sulfometuron 

Methyl.

Degradate Name ECOSAR Class Organism Toxicity Endpoint Degradate

Toxicity 

Value

(mg/L)24

Parent 

EEC 

(mg/L)

pyrimidine amine

(2-Pyrimidinamine, 4,6-dimethyl

)

Anilines –

aromatic amines

Fish1 96-hr LC50

Chronic value

61

0.29

0.0315

0.0205

Neutral organics Daphnid1 48-hr LC50

Chronic Value**

700

27

0.0315

0.0205

Green Algae1 96-hr EC50

Chronic value**

101

30

0.0315

0.0205

 24 When possible, the ECOSAR class that best predicts the toxicity for each degradate/taxon combination was 

chosen by comparing laboratory toxicity data and ECOSAR-predicted toxicity values for related degradates of 

registered sulfonylurea herbicides. 
65

Degradate Name ECOSAR Class Organism Toxicity Endpoint Degradate

Toxicity 

Value

(mg/L)24

Parent 

EEC 

(mg/L)

pyrimidine-ol

(2-Hydroxy, 4,6-dimethyl 

pyrimidine )

Phenols Freshwater fish 96-hr LC50

30-day Chronic 

value***

60

3.6

0.0315

0.0262

Daphnid 48-hr LC50

21-day Chronic 

value

16

3.1

0.0315

0.0262

Green algae 96-hr EC50

Chronic value**

79

38

0.0315

0.0205

Lemna gibba 7-day EC50 62 0.0315

Saltwater fish 96-hr LC50 67 0.0315

Sulfonamide

( 2-(Aminosulfonyl) benzoic 

acid, methyl ester )

Esters Freshwater fish 96-hr LC50

32/33-day Chronic 

value

151

18

0.0315

0.0262

Daphnid 48-hr LC50

21-day Chronic 

value

364

316

0.0315

0.0262

Mysid shrimp 96-hr LC50

Chronic value**

419

4.3x105*

0.0315

0.0205

Saltwater fish 96-hr LC50

Chronic value**

256

30+

0.0315

0.0205

Amides Freshwater fish 96-hr LC50

Chronic value**

268

1.6

0.0315

0.0205

Daphnid 48-hr LC50

Chronic value**

98

1.3

0.0315

0.0205

Green algae2 96-hr EC50

Chronic value**

1.1

0.36

0.0315

0.0205

free acid sulfonamide

2-(Aminosulfonyl) benzoic acid

Amides-acid Fish 96-hr LC50

Chronic value**

11669*

69

0.0315

0.0205

Daphnid 48-hr LC50

Chronic value**

3192*

42+

0.0315

0.0205

Green algae2 96-hr EC50

Chronic value**

17

3.4

0.0315

0.0205 1 ECOSAR class was chosen by comparing laboratory toxicity data and ECOSAR-predicted toxicity values for 

related degradate of dimethoxy aminopyrimidine (see Table 12). 2 ECOSAR class (amides) was chosen by comparing laboratory toxicity data and ECOSAR-predicted toxicity 

values for related degradate of IND1R84.

* predicted toxicity value may exceed compound’s aqueous solubility 

** duration associated with the reported chronic value was not reported by the ECOSAR program 

*** 60-day chronic value of 0.004 mg/L was deemed unreliable based on the paucity of underlying data used to generate the 

value

+ The toxicity value was determined from a predicted SAR using established ACR ratios and ECOSAR regression techniques.

Table 12. Toxicity Data and QSAR Analysis for Dimethoxy Aminopyrimidine (CP 17477)

Endpoint CP 17477 

(PPDB data1)

CP 17477

(ECOSAR – aromatic 

amine SAR)

CP 17477

(ECOSAR – neutral 

organic SAR)

Fish 96-h LC50 97 mg/L (rainbow trout) 79 mg/L 920 mg/L
66

Fish chronic toxicity value2 No data 0.38 mg/L 90 mg/L

Algae 96h EC50 120 mg/L (P. subcapitata) 9.2 mg/L 130 mg/L

Lemna 7-d EC50 >100 mg/L No prediction No prediction

Daphnid 48-h EC50 >100 mg/L 2.4 mg/L 469 mg/L

Daphnid chronic toxicity value2 24 mg/L (21-d NOEC) 0.05 mg/L 36 mg/L 1 Other company chemical codes for this metabolite include INJV0290, AE-F092944, and HOE092944. Aquatic 

toxicity data were retrieved from PPDB through a search for the string “2-amino-4,6-dimethoxypyrimidine” or for 

“AE-F092944” (duplicate entries for this compound in the database may not contain this information). The Pesticide 

Properties Database (aka. Footprint) may be accessed at: http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

2

 ChV = ECOSAR chronic toxicity value

Degradate toxicity in comparison to parent toxicity

Also important to the analysis of degradate toxicity is the comparative data for parent compound 

– both measured and ECOSAR predictions for parent are summarized and compared to EECs in 

Table 6 and provided in more detail in Table 13. ECOSAR-predicted toxicities for 

sulfometuron methyl are based on returned results for toxicity endpoints for three ECOSAR 

classes: esters, amides, and sulfonylureas. Collectively, ECOSAR predicted the toxicity of 

sulfonylureas to be slightly toxic to practically non-toxic to fish, daphnids, and mysid shrimp on 

an acute exposure basis – similar to the level of toxicity for sulfometuron methyl degradates 

discussed above. Also, this is similar to observed data from registrant-submitted studies (also 

provided in Table 13). The predicted toxicity of each of the degradates to non-vascular plants / 

algae was much lower (Table 10 and Table 11) than parent toxicity supporting a conclusion that 

the primary effects on plants from sulfometuron methyl application likely come from exposure to 

the parent molecule.

Table 13. ECOSAR-predicted and Observed Toxicity Values for Parent Sulfometuron 

Methyl

Organism Toxicity 

Endpoint

Toxicity Value (mg/L)

Registrantsubmitted data1ECOSAR class

Esters Amides Sulfonylureas

Freshwater 

fish

96-hr LC50

Chronic value

>148

No data

72

6.9

79

0.47 No predictions

Daphnid 48-hr LC50

Chronic value

>150

97

154

105

40

0.53+

134

12+

Green algae 96- or 120-hr EC50

Chronic value

0.0046

No data

68

16

0.96

0.61

0.04

0.01+

Mysid 

shrimp

96-hr LC50

Chronic value

>44.8

No data

121

16516* No predictions No predictions

Saltwater 

fish

96-hr LC50

Chronic value

>45

No data

111

15+ No predictions No predictions

* predicted toxicity value may exceed compound’s aqueous solubility 

+ The toxicity value was determined from a predicted SAR using established ACR ratios and ECOSAR regression techniques. 1 from Table 4
67

Comparisons to measured toxicity values for related pesticide degradates

Many sulfonylurea herbicides have similar degradates to each other (where sulfometuron methyl 

relates structurally to many other sulfonylurea herbicides with similar degradates is summarized 

in Section 3.2 above. In this section we provide some context to the sulfometuron degradate 

toxicological analysis for the pyrimidine amine degradate by an analysis of the available toxicity 

data for a similar degradate produced by several other sulfonylurea herbicides. 

Confidence in the ability of ECOSAR to predict the toxicity of degradates of sulfometuron 

methyl was assessed by comparing observed endpoint values from laboratory studies with 

ECOSAR-predicted values for dimethoxy aminopyrimidine (CP17477), a pyrimidine degradate 

of a number of sulfonylurea herbicides that is structurally similar to the pyrimidine amine (4,6-

dimethyl-2-pyrimidinamine) degradate of sulfometuron methyl.

Results for dimethoxy aminopyrimidine (a degradation product of many registered sulfonylurea 

herbicides which is predicted to have a similar toxicological profile to the dimethyl 

aminopyrimidine formed from the degradation of sulfometuron methyl) were previously 

discussed in the halosulfuron methyl Problem Formulation (DP Barcode: D394807; 3/8/2012), 

including both direct test data and QSAR results from ECOSAR. Table 12 shows the observed 

values recorded in the Pesticide Properties Database (PPDB) maintained by the FOOTPRINT 

Project25 and predicted toxicity using either neutral organic or aromatic amine structure-activity 

relationships in ECOSAR. Based on the data available in the PPDB database, the measured 

values are within the range of the predicted values by ECOSAR. The aromatic amine ECOSAR 

class best predicts toxicity to freshwater fish, and the neutral organic ECOSAR class best 

predicts toxicity to algae and daphnia. This analysis suggests that ECOSAR may serve as a 

reliable predictor of toxicity values for the pyridimine amine degradates of sulfonylureas. 

 25 More information accessible at: http://sitem.herts.ac.uk/aeru/footprint/.