UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

DATE: 

SUBJECT: 

FROM: 

THRU: 

TO: 

May 14,2013 

Registration Review- Preliminary Problem Formulation for the Ecological Risk 

Assessment for Trifloxysulfuron-Sodium (PC Code 119009; DP Barcode 408408) 

Tanja Crk, M.A., Biologist ]~·..._ C4_ J/ttt /13 

James K. Wolf, Ph.D., Environmental Scientist 

Environmental Risk Branch 3 <J..~~ IC w~ Environmental Fate and Effects Division (7507P) V .. -., ) J 

Dana Spatz, Branch Chief 

Rosanna Louie-Juzwiak, RAPL 

Environmental Risk Branch 3 

Environmental Fate and Effects Division (7507P) 

Kelly Ballard, Chemical Review Manager 

Neil Anderson, Chief 

Risk Management and Implementation Branch 1 

Pesticide Reevaluation Division (7508P) 

s- )Y ~t3 

~"""'~~-

~ :s/t't{2t>,e, 

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation (attached) for the ecological risk and endangered species assessments to be 

conducted as part ofthe Registration Review oftrifloxysulfuron-sodium. This document is 

intended to provide an overview of what is currently known regarding the environmental fate and 

ecological effects associated with trifloxysulfuron-sodium and its degradation products, and 

outlines uncertainties regarding attributes of the parent compound and its transformation 

products. It describes the preliminary ecological risk hypothesis and the processes that will be 

used during the completion of the ecological risk assessment in support of Registration Review. 
2 

 

Problem Formulation for the 

Ecological Risk Assessment in Support of the 

Registration Review of Trifloxysulfuron-Sodium

Trifloxysulfuron-Sodium 

Prepared by: 

James K. Wolf, Ph.D., Environmental Scientist 

Tanja Crk, M.A., Biologist 

Reviewed by: 

Melissa Panger, Ph.D., Senior Biologist 

James Hetrick, Ph.D., Senior Advisor 

Rosanna Louie-Juzwiak, RAPL 

Approved by: 

Dana Spatz, Branch Chief 

Environmental Risk Branch III 

Environmental Fate and Effects Division 

May 14, 2013 
3 

1. INTRODUCTION 

The purpose of this problem formulation is to provide EFED’s current understanding of the 

environmental fate and ecological effects of the registered uses of trifloxysulfuron-sodium 

[2-Pyridinesulfonamide,N-[[(4,6-dimethoxy-2-pyrimidinyl)-amino]carbonyl]-3-(2,2,2-

trifluoroethoxy)-, monosodium salt]. This document provides a plan for analyzing data relevant 

to trifloxysulfuron-sodium and for assessing potential risk to non-target organisms, including 

Federally-listed endangered/threatened species (hereafter referred to as “listed” species), and 

potential exposure in drinking water for the human health risk assessment. 

Trifloxysulfuron-sodium is the active ingredient (a.i.) in selective herbicides intended to control 

or suppress a variety of broadleaf, sedge and grass weeds as a post-emergence uses on cotton, 

sugarcane, citrus, almonds; for pre-emergence and post-emergence on tomatoes, and on 

established turf. Trifloxysulfuron-sodium slows or stunts plant growth (or causes ultimate plant 

death) by limiting amino acid synthesis in plants through inhibition of acetolactate synthase 

(ALS). Other chemical families of ALS-inhibitors are the imidazilinones (imazapyr, imazaquin), 

the triazolopyrimidines (flumetsulam), the pyrimidinyl(thio)benzoates (pyrithiobac-sodium), and 

the sulfonyaminocarbonyltriazolinones (flucarbazone-Na). 

The end use products proposed for trifloxysulfuron-sodium consist of water dispersible granules 

and emulsifiable concentrates containing 75% trifloxysulfuron-sodium as the active ingredient, 

and a granular co-formulated with the active ingredients 0.7 % trifloxysulfuron-sodium and 79.3 

% prometryn (CAS Reg No. 7287-19-6; PC Code 080805). 

Additionally, this problem formulation is intended to identify data gaps, uncertainties, and 

potential assumptions used to address those uncertainties, relative to characterizing the 

ecological risk associated with the registered uses of trifloxysulfuron-sodium. 

The structure of trifloxysulfuron-sodium, as well as the chemical name and other identifiers are 

provided in Table 1. Trifloxysulfuron-sodium (salt) will dissociate, losing the sodium ion, under 

environmentally relevant conditions (pKa = 4.76). Trifloxysulfuron-sodium is structurally 

similar to trifloxysulfuron (acid) which is also shown in Table 1. 

 
4 

Table 1. Trifloxysulfuron-sodium Chemical Identifiers 

2. Parameter 3. Identifier 

Trifloxysulfuron-sodium 

(salt) 

Chemical Structure 

Empirical Formula C14H13F3N5NaO6S 

Chemical Name 

And Synonyms 

IUPAC: sodium N′-(4,6-dimethoxypyrimidin-2-yl)-N-[3-(2,2,2-trifluoroethoxy)-2-

pyridylsulfonyl]imidocarbamate 

Sodium (4,6-dimethoxypyrimidin-2-yl)({[3-(2,2,2-trifluoroethoxy)pyridin-2-

yl]sulfonyl}carbamoyl)azanide 

2-Pyridinesulfonamide,N-[[(4,6-dimethoxy-2-pyrimidinyl)-amino]carbonyl]-3-(2,2,2-

trifluoroethoxy)-, monosodium salt 

Trifloxysulfuron sodium salt 

Trifloxysulfuron-sodium 

CAS Number 290332-10-4 (from US EPA) (sodium salt monohydrate) 

199119-58-9 (from www.hclrss.demon.co.uk) (sodium salt) 

Company Code CGA-362622 

Trifloxysulfuron Chemical Identifiers 

Trifloxysulfuron (acid) 

Chemical Structure 

Empirical Formula C14H14F3N5O6S 

Chemical Name 

And Synonyms 

IUPAC: 1-(4,6-dimethoxypyrimidin-2-yl)-3-[3-(2,2,2-trifluoroethoxy)-2-pyridylsulfonyl]urea 

CAS: N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(2,2,2-trifluoroethoxy)-2-

pyridinesulfonamide

CAS Number 145099-21-4 

Company Code CGA-292230 
5 

2. USE CHARACTERIZATION 

In addition to the technical product (Reg. No. 100-1133), there are three end-use products that 

contain trifloxysulfuron-sodium: Envoke Herbicide (Reg. No. 100-1132), Monument 75 WG 

Herbicide (Reg. No. 100-1134), and Suprend Herbicide (Reg. No. 100-1163) which also contains 

the active ingredient Prometryn (PC Code 080805). A special local needs registration (24c) has 

used Envoke Herbicide (Reg. No. MS11004). A summary of all the trifloxysulfuron-sodium 

products is provided in Table 2. 

Table 2. Trifloxysulfuron-sodium Formulated Products 

EPA 

Registration 

Number

Product Name 

CAS No. Amount Active 

Ingredient 

(% AI) 

(Product Code) 

Physical Forum 

100-1132 Envoke® Herbicide 290332-10-4 75 Emulsifiable Concentrate 

100-1133 Trifloxysulfuron-sodium Technical 290332-10-4 94 Technical 

100-1134 Monument® 75WG Herbicide 290332-10-4 75 Water Dispersible 

100-1163 SuprendTM Herbicide a 199119-58-9 0.7 Granular 

MS110004 Envoke® Herbicide 290332-10-4 75 Emulsifiable Concentrate a

 Prometryn (79.3 % AI) 2,4-bis (isopropylamino)-6-methylthio-s-triazine (CAS Reg. No. 7287-19-6). 

Based on the usage report prepared by OPP’s Biological and Economic Analysis Division, 3000 

and 1000 pounds (ai) of trifloxysulfuron-sodium is used per year on corn and sugar cane, 

respectively.1 Usage data for other uses (i.e., non-agricultural uses) are not available. All 

currently registered uses of trifloxysulfuron-sodium are listed in Table 3. 

 

1

 BEAD, 2013 Usage/Use Report in Support of Registration Review for Trifloxysulfuron sodium (119009), Screening Level 

Usage Analysis (SLUA) Date: June 15, 2012 
Table 3. Registered Uses, Application Rates and Methods of Trifloxysulfuron-sodium Applications. 

Site Description Reg# 

A. I. Max App 

Rate 

(lb ai/a) 

Max 

# 

Apps 

@ 

Max 

Rate 

/ CC 

A. I. Max 

App 

Rate/Year 

Product 

Seasonal 

Max 

Dose/CC 

A. I. 

Seasonal 

Max 

Dose/CC 

Max 

# 

Apps 

@ 

Max 

Rate / 

Unit 

of 

Time 

Minimum 

Retreatment 

Interval 

Application 

Method 

Type 

AGRICULTURAL FALLOW/IDLELAND / CONSERVATION RESERVE 

100-1132 .007031 NS .01875 NS NS NS NS Spray. 

AIRPORTS/LANDING FIELDS 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. AIRPORTS/LANDING FIELDS 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. ALMOND 100-1132 0.01875 NS NS 1.2 oz / a .0563 NS 30 d Spray. CITRUS 100-1132 0.01875 NS NS 1.2 oz / a .0563 NS 30 d Spray. COMMERCIAL/INDUSTRIAL LAWNS 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. COMMERCIAL/INDUSTRIAL LAWNS 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. COTTON (UNSPECIFIED) 100-1163 0.0105 NS NS 2.7 .0189 NS 14 d Basal spray treatment. COTTON (UNSPECIFIED) 100-1163 0.0105 NS NS 2.7 .0189 NS 14 d Directed spray. COTTON (UNSPECIFIED) 100-1132 0.007031 NS .007031 NS NS NS 14 d Ground spray. COTTON (UNSPECIFIED) 100-1132 0.007031 NS .007031 NS NS NS 14 d Spray. COTTON (UNSPECIFIED) 100-1132 0.011719 NS NS .4 oz / a .0188 NS 14 d Directed spray. GOLF COURSE TURF 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. GOLF COURSE TURF 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. ORNAMENTAL SOD FARM (TURF) 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. 
7 

Site Description Reg# 

A. I. Max App 

Rate 

(lb ai/a) 

Max 

# 

Apps 

@ 

Max 

Rate 

/ CC 

A. I. Max 

App 

Rate/Year 

Product 

Seasonal 

Max 

Dose/CC 

A. I. 

Seasonal 

Max 

Dose/CC 

Max 

# 

Apps 

@ 

Max 

Rate / 

Unit 

of 

Time 

Minimum 

Retreatment 

Interval 

Application 

Method 

Type 

ORNAMENTAL SOD FARM (TURF) 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. RECREATIONAL AREAS 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. RECREATIONAL AREAS 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. RESIDENTIAL LAWNS 100-1134 0.02482 NS .079688 NS NS NS 28 d Spot treatment. RESIDENTIAL LAWNS 100-1134 0.024844 NS .079688 NS NS NS 28 d Spray. SUGARCANE 100-1132 0.014063 3 .070312 NS NS NS 14 d Directed 

spray. 

SUGARCANE 100-1132 0.014063 3 .070312 NS NS NS 14 d Spray. SUGARCANE 100-1132 0.014063 3 .070312 NS NS NS 14 d Spray. SUGARCANE 100-1132 0.028125 3 .070312 NS NS NS 14 d Directed 

spray. 

SUGARCANE 100-1132 0.028125 3 .070312 NS NS NS 14 d Directed 

spray. 

TOMATO 100-1132 0.009375 1 .014062 NS NS NS NS Directed 

spray. 

TOMATO MS110004 0.009375 1 NS .3 oz / a .0141 NS NS Directed 

spray. 

TOMATO MS110004 0.009375 1 NS .3 oz / a .0141 NS NS Spray. 
3. CONCLUSIONS FROM PREVIOUS RISK ASSESSMENTS 

One ecological risk assessment has been completed for trifloxysulfuron-sodium: the new 

chemical assessment (cotton, citrus, sugarcane, almonds, tomatoes, and turf; D2769882

; August 

11, 2003). EFED evaluated this assessment in association with the current toxicity, exposure, and 

usage information to determine if sufficient data are available and if further updates are needed 

to support registration review. 

Potential direct risk to terrestrial and aquatic vascular and non-vascular plants from the use of 

trifloxysulfuron-sodium is expected. There is also the potential for various indirect effects on 

non-target animal species due to the effects on the plant community (for example, depletion of 

food sources and habitat). The major conclusions presented in the new chemical assessment for 

trifloxysulfuron-sodium are summarized in Table and are briefly discussed in the subsections 

below. All registered uses will be considered as part of the registration review risk assessment. 

Table 4. Summary of Risk Concerns Identified for Trifloxysulfuron-Sodium in Previous Assessments

Birds Mammals Terrestrial 

Plants 

Terrestrial 

Inverts Fish Aquatic Inverts 

Aquatic 

Plants 

Groundwater 

Contamination Persistence Degradates of Concern 

-- -- √ -- -- -- √ √ √ -- 

*The checkmarks indicate that the particular element was found to have a risk concern in the previous assessment. 

For all proposed uses, trifloxysulfuron-sodium exceeded levels of concern (LOCs) for risk to 

terrestrial plants, non-listed and listed, as a result of spray drift and runoff. Label precautions for 

uses on citrus and almond groves suggest that fruiting trees may be very sensitive to 

trifloxysulfuron-sodium via spray drift. 

On all proposed uses, trifloxysulfuron-sodium in runoff exceeded LOCs for acute risk to aquatic 

plants. Trifloxysulfuron-sodium was found to be more phytotoxic to aquatic vascular plants at 

acidic than alkaline pH. 

Trifloxysulfuron-sodium did not exceed LOCs for non-listed or listed terrestrial and aquatic 

(freshwater; estuarine) animals. Trifloxysulfuron-sodium was determined as not toxic to birds or 

mammals. However, there is potential for indirect effects by loss of any plant habitats as a result 

of inadvertent exposure to the chemical. 

Trifloxysulfuron-sodium has the potential to leach to ground water and/or reach to surface water 

by direct runoff. If residues of trifloxysulfuron-sodium were to reach irrigation water sources in 

high enough concentrations, there is a potential for damage to vulnerable crops and non-target 

terrestrial plants. In surface water, runoff events may have an acute effect on aquatic vascular 

plants. 

 

2

 USEPA, 2003. Section 3.Trifloxysulfuron Sodium (“Trifloxysulfuron”) Section 3 for cotton, sugarcane, almonds, citrus, 

tomatoes, and turf 2- Pyridinesulfonamide, N-[[(4,6-Dimethoxy-pyrimidinyl)amino]carbonyl]-3-(2,2,2-trifluroethoxy), 

monosodium salt CAS Registry Number(s) 29032-10-4 (sodium salt monohydrate); 199119-58-9 (sodium salt); 1450099-41-4 

(free sulfonylurea), Company Code CGA 362622; August 11, 2003; DB Barcodes: D276988; D280727; D284104; D284108; 

D284113; D284117; D284478 
9 

Previous Drinking Water Assessments 

A drinking water assessment (DWA) was prepared by EFED at the time of the new chemical 

assessment for parent trifloxysulfuron-sodium only as highlighted in Table 5. 

The Health Effects Division (HED) determined that the residues of concern in drinking water are 

parent trifloxysulfuron, CGA-053052, CGA-382997, and CGA-3687323

. Structures and 

chemical names are given in Appendix A. In order to account for the potential residues of these 

breakdown products in water, the parent as well as the maximum percent formation of these 

metabolites (of the applied parent compound observed in 14C-environmental fate studies) were 

considered. Those values are 61% of the a.i. for CGA-053052 (hydrolysis at pH 5 after 30 days), 

54% of the a.i. for CGA-382997 (aerobic soil metabolism after 365 days), and 53% of the a.i. for 

CGA-368732 (hydrolysis at pH 7 after 30 days). To account for the total residues of concern, 

the conversion factor (from parent compound to all residues of concern) is, therefore, 2.68. This 

assumption results in conservative levels of the total residues of concern since it assumes that all 

of the compounds occur simultaneously, and does not consider the kinetics of their formation 

and dissipation. These total-residue estimated drinking water concentrations (EDWCs) have 

been used directly in the dietary assessment (see below) to estimate dietary exposure to 

trifloxysulfuron from food and drinking water. The surface water estimates were used for acute 

(10.26 ppb) and chronic (0.83 ppb) drinking water exposure assessments. 

Table 5. Summary of Estimated Surface and Ground Water Concentrations for Trifloxysulfuron-sodium 

and Associated Residues of Concern.

Exposure Duration Trifloxysulfuron-sodium 

(D276988; 08/20/03) 

Trifloxysulfuron-sodium + CGA-053052 + 

CGA-382997 + CGA-368732 a

Surface Water 

Conc., ppb b

Ground Water 

Conc., ppb c

Surface Water 

Conc., ppb 

Ground Water 

Conc., ppb 

Acute 3.83 0.032 10.26 0.086 

Chronic (non-cancer) 0.31 0.032 0.83 0.086 a HED included the following trifloxysulfuron-sodium metabolites, using maximum formation values of these 

degradates observed in available fate studies:0.61 for CGA-053052, 0.54 for CGA382997, and 0.53 for CGA368732; as provided in the MARC Report (TXR No. 0052100, 8/25/03). The conversion factor for 

trifloxysulfuron-sodium to all residues of concern is 2.68 (USEPA, 2008). b From the Tier II PRZM-EXAMS - Index Reservoir model. Input parameters are based on sugarcane grown in 

Florida. 

c From the SCI-GROW model assuming a maximum seasonal use rate of 0.0788 lb ai/A, a Koc of 29, and a half-life 

of 29.84 days. 

EFED will prepare a updated drinking water assessment for trifloxysulfuron-sodium and the 

drinking water degradates of concern (CGA-053052, CGA-382997, and CGA-368732) following 

EFED guidance appropriate at that time. Using EFED aquatic models, the drinking water 

assessment will incorporate model estimates of trifloxysulfuron-sodium and its degradates in 

surface water (e.g., PRZM-EXAMS) and groundwater (e.g., (PRZM-GW). 

 

3

 USEPA, 2003. Health Effects Division. Trifloxysulfuron-sodium: Metabolism Assessment Review Committee 

Report. DP Barcode D293085. August 25, 2003. 
10 

Clean Water Act Programs 

Trifloxysulfuron-sodium 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 trifloxysulfuron-sodium. Aquatic Life Ambient Water Quality 

Criteria documents or Aquatic life benchmarks have not been published for trifloxysulfuronsodium. 

The Agency will consider available monitoring data such as the USGS National Water Quality 

Assessment (NAQWA), USEPA STORET database and, California Depart of Pesticide 

Regulations (CDPR) Surface Water Database. The Agency invites submission of water quality 

data for this pesticide. To the extent possible, data should conform to the quality standards in 

Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and 

Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management 

Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in 

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

4. ENVIRONMENTAL FATE AND TRANSPORT 

Physical and Chemical Properties of Trifloxysulfuron-Sodium 

The physicochemical properties of trifloxysulfuron-sodium are shown in Table 6. Based on 

these properties alone, trifloxysulfuron-sodium is not expected to be volatile or to bioaccumulate. 

It is highly soluble in water. 

Table 6. Selected Physical/Chemical Parameters of Trifloxysulfuron-Sodium 

Parameter Value Source/Classification

Empirical Formula C14H13F3N5NaO6S 45371702

Molecular mass (molecular formula) 459.3 45371702 

Vapor Pressure, 25C * < 1.3 x 10-6 Pa 

<9.75 x 10-9 torr 45371702 

Henry’s Law Constant, 25C (Estimated) 2.6 x 10-5 Pa m3

/mol 

2.29 x10-13 atm m3

/mole 45371702 

Aqueous solubility (25C)

25.7 g/L @ pH 7.4 

(25,700 mg/L) 

No data are available on the solubility of this 

chemical at pH 5 and 9

45371702 

Log octanol-to-water partition coefficient 

(log KOW) 

1.40 @ pH 5 

-0.42 @ pH 7 

-1.60 @ pH 9.1 

45371702 

Dissociation Constant, pKa (acidic) 4.76 45371702 
11 

Environmental Fate Properties of Trifloxysulfuron-Sodium 

Environmental fate properties of trifloxysulfuron-sodium are summarized in Table 7. 

These half-life estimates will be updated to reflect current guidance, if needed, from previous 

assessments to reflect the NAFTA degradation kinetics guidance.4 The results are similar to 

those previously reported in the data evaluation records (DERs). For many studies, the DERs 

indicated that trifloxysulfuron-sodium transformation could not always be adequately described 

using single first order kinetics. 

Hydrolysis is the major route of transformation in the environment. Rates of hydrolysis (halflives) and types, mechanism of formation, and predominance of degradation products is pHdependent. Given the considerable variability in soil and water pH across the proposed use area, 

considerable variability in persistence and nature of degradates is to be expected. Like all of the 

sulfonylurea herbicides, trifloxysulfuron-sodium is very mobile. Although the persistence and 

mobility of trifloxysulfuron-sodium in soils may be considered moderate when compared to 

other very persistent and mobile sulfonylurea herbicides (e.g., chlorsulfuron), there is still the 

potential for leaching and runoff. The chemical names and abbreviation of the major 

degradation/transformation products are listed in Table 9. Chemical names and structures are 

given in Appendix A. 

At acidic pHs, hydrolysis is faster than at neutral-to-basic pHs (half-lives of 6 days at pH 5 and 

20-22 days at pH 7 and 9). The products prevailing under acidic condition are distinctly different 

as those prevailing under alkaline conditions and are formed by very different chemical 

mechanisms. The predominant products in acidic media contain a single ring, CGA-382997 

(pyridine) and CGA-53052 (pyrimidinyl). These degradates are formed by cleavage of the 

sulfonylurea bridge. The predominant products under alkaline conditions have the two rings, but 

a shorter bridge and are formed by elimination of the sulfonyl and the urea groups, followed by 

re-bridging. These degradates are CGA-368732, CGA-368733, and NOA-436664. This bridge 

elimination/re-bridging mechanism has been documented for other sulfonylurea herbicides 

containing a pyridine ring, such as nicosulfuron and rimsulfuron. A generalized degradation 

pathway of trifloxysulfuron-sodium in the environment is shown in Figure 1. 

 

4 Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media, Health Canada, U.S. 

Environmental Protection Agency, December 2012. 
12 

Figure 1. Degradation Pathways of Trifloxysulfuron-sodium in the Environment. 

 

The estimated half-lives of trifloxysulfuron-sodium are 29-79 days in aerobic soils (DT90 > 235 

days), 9-13 days in anaerobic water-sediments, 11- 16 days in aerobic water-sediment systems, 

and 9-25 days in California and 6-10 days in Louisiana in field dissipation studies. The pHdependent predominance of one type of degradate over the other was observed in both 

homogeneous aqueous media (abiotic hydrolysis study), in heterogeneous media (soils; watersediment systems), and in the field. Of all the degradation products, CGA-382997 appears to be 

the most persistent. The degradate CGA-53052 is also a common degradate of other sulfonylurea 

herbicides. The half-lives for the degradates of concern which were found in the aerobic soil and 

aerobic and anaerobic aquatic metabolism studies are also shown in Table 7. 

The transformation of trifloxysulfuron-sodium in water-sediment systems, while dominated by 

hydrolytic reactions (abiotic), includes a clearly metabolic pathway that involves loss of a methyl 

group from the 4,6-dimethoxypyrimidinyl moiety to form NOA-436664. This metabolic pathway 

was not observed in laboratory studies conducted with soils or in abiotic aqueous media, but it 

was identified in the field. While the rates of transformation under aerobic and anaerobic 

conditions were comparable (14-21 days for the bulk system), some variation was found in the 

amount and distribution of products between the aqueous and sediment phases. However, under 

the experimental conditions of the studies, formation of bridge-contraction products was 

significant, but formation of cleavage products was not. See Table 9. 
13 

Photolysis in water (direct) or on soil is not an important transformation pathway for 

trifloxysulfuron-sodium. Volatilization is not anticipated to be a significant dissipation pathway 

from soil. 

Trifloxysulfuron-sodium and three of its degradates (CGA-382997, CGA-53052, and CGA368732) do not bind strongly to soils and have leaching and runoff potential. Binding to soils is 

stronger for the degradates CGA-368733 and NOA-436664. In water-sediment studies these 

degradates were predominantly found in the sediment. Thus, trifloxysulfuron-sodium, CGA382997, CGA-53052, and CGA-368732 are the chemical species that would most likely be 

found in water 
14 

Table 7. Environmental Fate Parameters of Trifloxysulfuron-Sodium and degradates 

Parameter Value Source/Classification

Persistence

Hydrolysis half-life (25C) 

2.7- 2.9 days @ pH 4 

5.7 - 5.8 days @ pH 5 

19.8 - 20.8 days @ pH 7 

21.3 -22.2 days @ pH 9 

45371804 

45371805 

Aqueous photolysis half-life (25C @ pH 7) Pyrimidine label: 423 days 

Pyridine label: 63 days 

45371806 

45371807 

45893304 

Soil photolysis half-life (25C) Pyrimidine label: 79.5 days 

Pyridine label: 79.3 days 

45371808 

45371809 

Aerobic soil metabolism half-life (25°C) 

Trifloxysulfuron-sodium 

Pyridine label: t1⁄2 = 54 days 

Pyrimidine label: t1⁄2 = 79 days 

Trifloxysulfuron + degradates 

Pyridine label: t1⁄2 = 1695 daysa

Pyrimidine label: t1⁄2 = 371.6 daysb

45371810 

45371811 

45371810 

45371811 

Anaerobic aquatic metabolism half-life (25°C) 

(Total System: water + sediment) 

Trifloxysulfuron-sodium 

Pyridine label: t1⁄2 = 21.8 days 

Pyrimidine label: t1⁄2 = 15.9 days 

Trifloxysulfuron-sodium + degradates 

Pyridine label: t1⁄2 = 127.9 daysc

Pyrimidine label: t1⁄2 = 146.6 daysd 

45371812 

45371813 

45371812 

45371813 

Aerobic aquatic metabolism half-life (25°C) 

Trifloxysulfuron-sodium 

Pyridine label: t1⁄2 = 17.6 days 

Pyrimidine label: t1⁄2 = 21.1 days 

Trifloxysulfuron-sodium+ degradates 

Pyridine label: t1⁄2 = 43.9 dayse

Pyrimidine label: t1⁄2 = 92.3 daysf

45371814 

45371815 

45371814 

45371815

Mobility

Freundlich Kads and Koc See Table 8. -- 

Field Dissipation 

Terrestrial field dissipation half-life 

CA-cotton : t1⁄2 = 25 days 

CA-bare ground : t1⁄2 = 9 days 

LA-sugarcane : t1⁄2 = 10.4 days 

LA-bare ground : t1⁄2 = 5.8 days 

45371828 

45371829 

a

 Parent + degradates CGA-382997, CGA-368733 

b

 Parent + degradates CGA-53052, CGA-368733 

c

 Parent + degradates CGA-53052, CGA-368733 

d

 Parent + degradates CGA-382997, CGA-368733 

e

 Parent + degradates CGA-382997, CGA-368733 

f

 Parent + degradates CGA-53052, CGA-268733 
15 

The Freundlich sorption coefficients (Kads) and soil organic carbon coefficient (Koc) for the 

major degradates are shown in Table 8. 

Based upon soil organic carbon coefficient (Table 8), Koc, CGA-382997 would be mobile, 

trifloxysulfuron-sodium; CGA-53052, CGA-368732 would be mobile to moderately mobile; and 

CGA-368733 and NOA-436664 would be moderately mobile to slightly mobile, according to 

mobility classification scheme adapted from the FAO by EFED (USEPA, 20065

). 

Table 8. Freundlich Adsorption Coefficients (Kads) and Kocs for Trifloxysulfuron-sodium and its Major 

Degradates (5 U.S.A soils). 

Sorption 

Parameter 

Parent: 

Trifloxysulfuron

-Sodium 

CGA-382997 CGA-53052 CGA-368732 CGA-368733 NOA-436664 

MRID 45371825 45371721 4537123 45371820 45371824 45371816 

Kads (mL/g) 0.31- 0.88 0.17- 0.30 1.2- 2 0.26- 1.2 14- 137 3.9- 28

Koc (ml/goc) 29- 147 15- 50 75- 425 43- 200 875- 22817 650- 1925 

1/N 0.90 - 0.99 0.70 - 0.80 0.70 - 0.97 0. 90 - 0.96 0.56 - 0.93 0.71 - 0.83 

Transformation Products 

Trifloxysulfuron-sodium like other sulfonylurea herbicides containing a pyridine ring can 

eliminate the sulfonyl and the urea groups from the bridge and then re-bridge to form products 

with a shorter ring. The trifluoroethyl group in the pyridine is very stable. One of the degradates 

of trifloxysulfuron-sodium, CGA-53052 (4,6-dimethoxy-pyrimidine) is common to other 

sulfonylurea herbicides, such as rimsulfuron, nicosulfuron, and foramsulfuron. 

Table 9 summarizes the mechanisms by which trifloxysulfuron-sodium degrades together with 

the chemical names. Chemical structures are shown in Figure 1 and Appendix A. 

The cleavage products predominate at acidic pHs while the bridge-elimination/contraction 

products predominate at alkaline pHs. While this is a general observation, at intermediate pHs 

both types of degradates may form but at variable ratios. For this reason, it is expected that there 

would be considerable variation in exposure to specific degradates throughout the proposed use 

area. See Table 10 and compare the distribution of degradates depending on the pH of the media. 

The degradate CGA-382997 appears to be the most stable of the degradates, as it continues to 

form (i.e., increase) throughout the aerobic soil metabolism studies. At the present time, EFED 

has not determined the kinetics (rates of formation and decline; half-life) for the degradates in 

the aerobic soil metabolism studies or other systems. Although some fate studies do not allow for 

determination of the kinetics of the individual degradation products, data are sufficient to 

determine the degradation rate of the residues of concern using the total toxic residue (TTR) 

methodology. 

 

5

 USEPA, 2006. Standardized Soil Mobility Classification Guidance. Memorandum: S. Bradbury, April 21, 2006. 
16 

See Table 10 for the maximum amount of degradates formed in the soils and water (as percent 

of the applied 14C-parent). Note that all are major degradates, even though their relative amounts 

may vary in soils and water-sediment systems. Note also that NOA-436664 was not found in 

laboratory-scale aerobic soil metabolism studies, but that it was found in water-sediment systems 

and in the field. 

In the terrestrial field studies, the highest amount of the cleavage products were found in the 

acidic Louisiana plots and were also higher in the planted than in the bare-ground plot. After the 

third application, the degradate CGA-382997 in the 0-15 cm depth reached a maximum of 22.8 

ppb in the sugarcane plot and 15.3 ppb in the bare ground plot after 90 days. For CGA-53052, a 

maximum of 12.98 ppb was found after 121 days (cropped plot) and 9.91 after 90 days (bare 

ground plot). In the California study, residues of these degradates did not exceed 3.1 ppb in the 

0-15 cm sampling depth. In California, the highest amount of a bridge elimination/contraction 

product (CGA-368732) in the 0-15 cm depths was 8.3 in the cotton plot 21 days after the third 

application. This product was also the highest in the Louisiana plots (11 ppb 177 days after the 

third application). 

 
17 

Table 9. Chemical Names for Trifloxysulfuron-sodium and Its Major Transformation Products

Chemical Name and CAS Registry Number, if 

assigned 

Company Code Type of Transformation Product 

IUPAC Name: 4,6-Dimethoxy-pyrimidin-2-ylamine

CAS Name: 2-Pyrimidinamine,4,6-dimethoxyCAS #: 36315-01-2

CGA-53052 Cleavage product (pyrimidine ring) 

Other sulfonylurea herbicides generate this 

product 

IUPAC Name: (4,6-Dimethoxy-pyrimidin-2-yl)-urea

CAS Name: Urea, 4,6-dimethoxy-2- pyrimidinyl)- 

CAS #: 36315-01-2 

CGA 294409 Cleavage product (pyrimidine ring) 

Other sulfonylurea herbicides generate this 

product. 

CGA-294409 may be considered as a 

precursor to CGA-53052 

IUPAC Name: 3-(2,2,2-Trifluoro-ethoxy)-pyridine2-sulfonic acid amide.

CAS Name: 2-Pyridinesulfonamide-3-(2,2,2-

trifluoroethoxy)-

CAS #: NA

CGA-382997 Cleavage product (pyridine ring) 

This product is unique to trifloxysulfuron 

IUPAC Name: 1-(4,6-Dimethoxy-pyrimidin-2-yl)-

1-[3-(2,2,2-trifluoroethoxy)-pyridin2-yl)-urea 

CAS Name: Urea, N-(4,6-dimethoxy-2-

pyrimidinyl)-N-[3-(2,2,2-

trifluoroethoxy)-2-pyridinyl]- 

CAS #: NA

CGA-368732 Formed by elimination of the sulfonyl group 

in the bridge, followed by rebridging. Thus, 

the bridge in CGA-368732 is shorter than 

parent’s. 

This product is unique to trifloxysulfuron 

Bridge elimination/contraction product

IUPAC Name: (4,6-Dimethoxy-pyrimidin-2-yl)-[3-

(2,2,2-trifluoro-ethoxy)-pyridin-2-

yl]-amine 

CAS Name: 2-Pyrimidinamine,4,6-dimethoxy-N-

[3-(2,2,2-trifluoroethoxy)-2-

pyridinyl]- 

CAS #: NA

CGA-368733 Formed by elimination of the ureido group of 

CGA-368732, followed by rebridging. Thus, 

the bridge in CGA-368732 is shorter than in 

CGA-368732 

This product is unique to trifloxysulfuron 

Bridge elimination/contraction product

NOA-436664 

IUPAC Name: 6-Methoxy-2-[3-(2,2,2-trifluoroethoxy)-pyridin-2-ylamino]-

pyrimidin-4-ol

CAS Name: 4-(1H)-Pyrimidinone, 6-methoxy-2-

[[3-(2,22-trifluoroethoxy)-2-

pyridinyl]amino]- 

CAS #: NA

NOA-436664 This is the mono-desmethoxy product of 

CGA-368733 

This product is unique to trifloxysulfuron 

Bridge elimination/contraction product

 
18 

Table 10. Major Trifloxysulfuron-Sodium Environmental Transformation Products 

Trifloxysulfuron

-sodium 

Transformation 

Products 

[

14C] Label Hydrolysis Aqueous 

Photolysis2

Soil 

Photolysis2

Aerobic 

Soil 

Metabolism 

Anaerobic 

Aquatic 

Metabolism 

Aerobic Aquatic 

Metabolism 

%max/day/pH1 Maximum % of applied radioactivity (day maximum occurred) 

CGA 382997 

Pyrimidine - - - - - - 

Pyridine 

64.0 (30 d; 4 

52.5 (30 d;5) 

4.8 (30 d; 7) 

4.0 (30 d; 9) 

I: 5.3 (30 d) 

D: 5.1 (30 d) 

I: 10.1 (30 d) 

D: 17.2 (30 d) 54.1(273 d) 4.6 (270 d)3

 4.3 (100 d)3

CGA 53052 Pyrimidine 

61.1 (30 d; 4) 

49.8 (30 d;5) 

4.9 (30 d; 7) 

3.3 (30 d; 9) 

I: 7.54 (30 d) 

D: 9.2 (30 d) 

I: 3.3 (21 d) 

D: 1.3 (14 d) 14.1(179 d) 3.8 (21 d)4 3.2 (100 d)4 

Pyridine - - - - - 

CGA 368733 

Pyrimidine 

2.7 (30 d; 4) 

2.7 (30 d; 5) 

8.1 (30 d; 7) 

35.1 (30 d; 9) 

I: 6.4 (30 d) 

D: 3.4 (30 d) - 26.7 (365 d) 7.1 (181 d)4 37.0 (100 d)4

Pyridine 

1.9 (30 d; 4) 

5.1 (30 d; 5) 

9.3 (30 d; 7) 

29.8 (30 d; 9) 

I: 7.8 (30 d) 

D: 5.1 (26 d) 

I: 11.5 (30 d) 

D: 3.2 (30 d) 16.4 (365 d) 6.4 (270 d)4

 14.1 (100 d)4

CGA 368732 

Pyrimidine 

35.9 (30 d; 4) 

42.3 (30 d; 5) 

53.0 (30 d; 7) 

23.0 (30 d; 9 

I: 45.9 (30 d) 

D: 51.1 (30 d) 

I: 25.5 (21 d) 

D: 29.0 (30 d) 21.8 (90 d) 20.1 (21 d)3 30.9 (59 d)3

14 (59 d)4

Pyridine 

34.8 (30 d; 4) 

39.3 (30 d; 5) 

51.0 (30 d; 7) 

26.5 (30 d; 9) 

I: 46.1 (30 d) 

D: 49.0 (30 d) 

I: 6.2 (30 d) 

D: 1.1 (30 d) 12.5 (91 d) 16.7 (22 d)3

 19.2 (21 d)3

CGA 294409 

Pyrimidine - I: 2.0 (3 d) 

D: 5.8 (7 d) I: 2.4 (30 d) - - - 

Pyridine - - - - - 

NOA-436664 Pyrimidine - - I: 1.0 (30 d) - 45.7 (181 d)4 7.7 (100 d)4

Pyridine - - - - 37.2 (270 d)4 21.5 (59 d)4

1

 Maximum percent of applied radioactivity, days after treatment maximum occurred, pH. 2

 I = irradiated; D = Dark; Maximum percent of applied radioactivity and days after treatment. 3

 Water fraction 

4

 Sediment fraction. 

 
19 

5. RECEPTORS 

Table 11 and Table 12 provide a summary of the aquatic and terrestrial taxonomic groups, 

respectively, and the most sensitive surrogate species tested to characterize the potential acute 

and chronic ecological effects of trifloxysulfuron. The tables provide a preliminary overview of 

the potential acute toxicity of trifloxysulfuron by providing the acute toxicity classifications. 

Based on the available ecotoxicity information, the organisms facing the greatest hazard are 

aquatic and terrestrial plants. No toxicity data were submitted or identified in the open literature 

for the trifloxysulfuron-sodium or its transformation products. Additional transformation product 

data from other sulfonylurea chemicals were not available to supplement the data submitted for 

transformation products of trifloxysulfuron-sodium (i.e., CGA-382997, CGA-368732). Note that 

CGA-362622 is the parent compound. 

Four studies were identified in the OPPIN database for which a DER was not available; these 

studies are currently being processed for review. A preliminary, cursory review of the endpoints 

suggests the possibility of a more sensitive endpoint for duckweed (Lemna gibba; MRID 

47168201) than that provided in the tables below; the study author 7-day EC50 for the parent 

compound is 5.3 x10-5 mg a.i./L (NOAEC = 2.8 x 10-5 mg a.i./L) with frond number as the most 

sensitive parameter. The endpoint is a tentative estimate until the value is formally vetted and 

recalculated by the reviewers (Table 11). 

The remaining studies, all with the parent compound, suggest reduced toxicity (MRID 

47168202, non-vascular plant Anabaena flos-aquae, study author reported 120-hr cell density 

EC50 of 0.27 mg a.i./L and NOAEC of 0.20 mg a.i./L) or equivalent toxicity (MRID 45371803, 

Lemna minor, study author reported 6-day frond number EC50 of 0.00062 mg a.i./L; and, MRID 

45371732, Apis mellifera, 48-hr acute oral LD50 of >25 g a.i/bee) than the endpoints reported in 

the tables below. The endpoints are also tentative estimates until the values are formally vetted 

and recalculated by the reviewers. 

Table 11. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for Trifloxysulfuron 

Taxonomic 

Group 

Study 

Type 

Surrogate Species 

and 

Test Material 

Toxicity Value 

(all units in 

terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute 

Toxicity 

Classification 

Freshwater fish1 Acute 

850.1075 

Rainbow Trout –cold 

water species 

(Oncorhynchus 

mykiss) 

CGA-362622 

96.3% a.i. 

LC50: >103 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371713 

Acceptable 

(limit test) 

Practically 

nontoxic 

Rainbow trout 

(Oncorhynchus 

mykiss) 

Metabolite 

CGA-382997 

99.5% a.i. 

LC50: >96.7 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371715 

Supplementala

No more than 

slightly toxic 
20 

Taxonomic 

Group 

Study 

Type 

Surrogate Species 

and 

Test Material 

Toxicity Value 

(all units in 

terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute 

Toxicity 

Classification 

Rainbow trout 

(Oncorhynchus 

mykiss) 

Degradate 

CGA-368732 

99.5% a.i. 

LC50: >104 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371731 

Acceptable 

(limit test) 

Practically 

nontoxic 

Chronic 

(Early Life 

Stage) 

850.1400 

Rainbow Trout 

(Oncorhynchus 

mykiss) 

CGA-362622 

96% a.i. 

NOAEC: 9.52 

mg a.i./L 

LOAEC: >9.52 

mg a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371721, 

45893302 

Supplementalb 

-- 

Estuarine/Marine 

fish 

Acute 

850.1075 

Sheepshead Minnow 

(Cyprinodon 

variegatus) 

CGA-362622 

96.3% a.i. 

LC50: >103 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371720 

Acceptable 

(Limit test) 

Practically 

nontoxic 

Freshwater 

invertebrates 

Acute 

850.1010 

Water Flea (Daphnia 

magna) 

CGA-362622 

96.3% a.i. 

EC50:>108 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371716 

Acceptable 

(Limit test) Practically 

nontoxic 

Water Flea (Daphnia 

magna) 

Metabolite 

CGA-382997 

99.5 % a.i. 

EC50:>99.5 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371717 

Acceptable 

(Limit test) 

Practically 

nontoxic 

Water Flea (Daphnia 

magna) 

Degradate 

CGA-368732 

99.5 % a.i. 

EC50:>119 mg 

a.i./L 

Most sensitive 

endpoint: none. 

5% mortality in 

second highest 

test conc. 

Sublethal effects: 

quiescence, 

extraneous 

material on 

organisms 

45371730 

Acceptable 

Practically 

nontoxic 
21 

Taxonomic 

Group 

Study 

Type 

Surrogate Species 

and 

Test Material 

Toxicity Value 

(all units in 

terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute 

Toxicity 

Classification 

Chronic 

850.1300 

Water Flea (Daphnia 

magna) 

CGA-362622 

96.0% a.i. 

NOAEC: 0.549 

mg a.i./L 

LOAEC: 1.23 

mg a.i./L 

Most sensitive 

endpoint: 

Reproduction 

(#of 

offspring/repro 

day) 

45371722 

Acceptable -- 

Estuarine/Marine 

invertebrates 

Acute – 

shell 

deposition 

study 

850.1025 

Eastern Oyster 

(Crassostrea 

virginica) 

CGA-362622 

96.3% a.i. 

EC50: >103 mg 

a.i./L 

NOAEC: 103 mg 

a.i./L 

Most sensitive 

endpoint: none 

No sublethal 

effects reported. 

45371719 

Acceptable 

(Limit test) 

Practically 

nontoxic 

Acute – 

shrimp 

850.1035 

Mysid Shrimp 

(Mysidopsis bahia) 

CGA-362622 

96.3% a.i. 

LC50: 60.1 mg 

a.i./L 

NOAEC: 9.16 

mg a.i./L 

Most sensitive 

endpoint: 

mortality 

No sublethal 

effects reported. 

45371718 

Acceptable Slightly toxic 

Aquatic plants and 

algae 

Nonvascular 

850.4500 

Green alga 

(Selenastrum 

capricornutum) 

CGA-362622 

96% a.i. 

EC50: 0.0065 mg 

a.i./L 

NOAEC: 

0.00113 mg 

a.i./L 

Most sensitive 

endpoint: cell 

density. 

45371725 

Acceptable -- 

Nonvascular 

850.4500 

Green alga 

(Selenastrum 

capricornutum) 

Degradate 

CGA-368732 

99.5% a.i. 

EC50: 23 mg 

a.i./L 

NOAEC: 6.8 mg 

a.i./L 

Most sensitive 

endpoint: cell 

density. 

45371729 

Supplementalc 
22 

Taxonomic 

Group 

Study 

Type 

Surrogate Species 

and 

Test Material 

Toxicity Value 

(all units in 

terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute 

Toxicity 

Classification 

Nonvascular 

850.4500 

Green alga 

(Pseudokirchneriella 

subcapitata) 

Metabolite 

CGA-382997 

99.5% a.i. 

EC50: >95.85 mg 

a.i./L 

Most sensitive 

endpoint: none. 

No abnormalities 

observed.2 

45371727 

Supplementalc

 

(Limit test) 

-- 

Vascular 

850.4400 

Duckweed (Lemna 

gibba) 

CGA-362622 

93 % a.i. 

EC50: 0.000240 

mg a.i./L 

NOAEC: 

0.00001024 mg 

a.i./L 

Most sensitive 

endpoint: frond 

number 

45371802 

Acceptable 

-- 

Duckweed (Lemna 

gibba) 

CGA-362622 

98.1 % a.i. 

Tentative values: 

EC50: 0.000053 

mg a.i./L 

NOAEC: 

0.000028 mg 

a.i./L 

Most sensitive 

endpoint: frond 

number 

47168201 

In review 

1

Freshwater fish represent surrogates for aquatic-phase amphibians. 2

The 72-hour percent inhibition in cell density in the mean measured 95.85 mg a.i./L treatment group was -45%, 

compared to the control. 

a

 Several guideline deviations, collectively, do not allow the study to be considered acceptable by USEPA criteria. b

 A LOAEC was not determined and the raw data for growth was not submitted; only mean values for each replicate 

instead of the value for each individual were provided. c

 Numerous deviations from US EPA guideline recommendations. Most importantly, study was conducted for 72-

hours, which is reviewed as a Tier I study. 

Table 12. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for Trifloxysulfuron 

Taxonomic 

Group Study Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

(all units in terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute Toxicity 

Classification 

Birds1 Acute 

850.2100 

Mallard Duck 

(Anas 

platyrhynchos) 

CGA-362622 

96.3% a.i. 

LD50: >2250 mg a.i./kgbw 

No mortality. No 

sublethal effects 

reported. Regurgitation 

in one female. 

45371707 

Acceptable 

(gavage) 

Practically 

nontoxic2 
23 

Taxonomic 

Group Study Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

(all units in terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute Toxicity 

Classification 

Sub-acute 

dietary 

850.2200 

Mallard Duck 

(Anas 

platyrhynchos) 

CGA-362622 

96.3% a.i. 

LC50: >5800 mg a.i./kg 

No mortality. No 

sublethal effects 

reported. 

45371709 

Acceptable 

Practically 

nontoxic2 

Chronic 

1-gen repro 

850.2300 

Mallard Duck 

(Anas 

platyrhynchos) 

CGA-362622 

96 % a.i. 

NOAEC: 106 mg 

a.i./kg-diet 

LOAEC: 201 mg 

a.i./kg-diet 

Adult parameters not 

affected. 

Most sensitive endpoint: 

# of hatchlings/live 3-

wk embryos and 

hatchling survival/eggs 

set 

45371711 

Acceptable -- 

Mammals 

Acute Oral 

870.1100 

Laboratory rat 

(Rattus 

norvegicus) 

CGA-362622 

95.7% a.i. 

LD50: >5,000 mg 

a.i./kg-bw 

Mortality (2/5 females). 

No adverse effect on 

body weight gain. 

Sublethal effects: 

piloerection, hunched 

posture hypoactivity, 

dyspnea. 

45371923 

Acceptable 

 (gavage) 

Practically 

nontoxic2

Acute Oral 

870.1100 

Laboratory rat 

(Rattus 

norvegicus) 

CGA-362622 

75% a.i. (TEP) 

LD50: >5,000 mg 

form/kg-bw 

LD50: >3,750 mg 

a.i./kg-bw 

No mortality, no 

adverse effect on body 

weight gain. No 

sublethal effects. 

45371924 

Acceptable 

(Limit study) 

 (gavage) 

Practically 

nontoxic2

Acute Oral 

870.1100 

Laboratory rat 

(Rattus 

norvegicus) 

CGA-362622, 

0.77% 

Prometryn, 79.2% 

(TEP) 

LD50: >2,000 mg 

form/kg-bw 

LD50: >15.4 mg a.i./kgbw 

No mortality. Body 

weight gain. 

Sublethal effects: slight 

piloerection, slightly 

reduced activity, 

slightly hunched 

posture. Normal by day 

3 post treatment. 

45762303 

Acceptable 

(Limit study) 

 (gavage) 
24 

Taxonomic 

Group Study Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

(all units in terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute Toxicity 

Classification 

Acute 

Inhalation 

(4-hr) 

870.1300 

Laboratory rat - 

Wistar 

(Rattus 

norvegicus) 

CGA-362622, 

0.78% 

Prometryn, 79.3% 

LC50: > 5.14 mg form/L 

LC50: > 0.04 mg a.i./L 

No mortality. Body 

weight gain. 

Sublethal effects: wet 

fur, reduced breathing 

rate, salivation, reduced 

response to sound, 

hunched posture, 

piloerection, 

chromodaccryorrhea, 

stains around nose, 

upper respiratory tract 

irritation, decreased 

activity, reduced foot 

withdrawal reflex, 

tremors. Recovery by 

day 3. Pelvic dilatation 

and speckled thymus at 

necropsy. 

45762305 

Acceptable 

(Limit study) 

-- 
25 

Taxonomic 

Group Study Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

(all units in terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute Toxicity 

Classification 

Chronic 

2-gen repro 

870.3800 

Laboratory rat 

(Rattus 

norvegicus) 

CGA-362622 

94.6% a.i. 

Parental Toxicity

NOAEL: 1000 ppm 

(78.8/83.5 mg/kgbw/day m/f) 

LOAEL: 8000 ppm 

(631/676.4 mg/kg-bw 

/day m/f) 

Endpoint: decreased 

body wt, body wt gain, 

food consumption in P 

and F1 m & f 

Offspring Toxicity

NOAEL: 1000 ppm 

(78.8/83.5 mg/kg-bw 

/day m/f) 

LOAEL: 8000 ppm 

(631/676.4 mg/kg-bw 

/day m/f) 

Endpoint: decreased 

body wt, body wt gain, 

spleen and thymus wts 

in F1 and F2 pups, 

increased vaginal 

patency in F1 pups 

Reproductive 

performance

NOAEL: 12,000 ppm 

(968.3/1029.6 mg/kgbw /day m/f) 

LOAEL: Not observed 

Endpoint: N/A 

45372007 

(definitive) 

45372023 

(range finding) 

Acceptable 

--

Insects 

Acute 

contact 

850.3020 

Honey bee 

(Apis mellifera 

L.) 

CGA-362622 

96.3% a.i. 

LD50: >25 μg a.i./bee 

No mortality or 

sublethal effects 

reported. 

45371728 

Acceptable 

(Limit test) 

Practically 

nontoxic2 

Terrestrial 

plants 

Vegetative 

Vigor 

(Tier II) 

850.4150 

Dicot – Radish 

(Raphanus 

sativus) 

CGA-362622 

75.2% a.i. (TEP) 

NOAEC = 0.00002 lbs 

a.i./acre 

IC25 = 0.000009 lbs 

a.i./acre 

Endpoint: Shoot dry 

weight 

45371734 

Acceptable -- 

Monocot – 

Ryegrass 

(Lolium perenne) 

CGA-362622 

75.2% a.i. (TEP) 

NOAEC = 0.0059 lbs 

a.i./acre 

EC25 = 0.0056 lbs 

a.i./acre 

Endpoint: Shoot dry 

weight 

45371734 

Acceptable -- 
26 

Taxonomic 

Group Study Type 

Surrogate 

Species 

and 

Test Material 

Toxicity Value 

(all units in terms of 

measured active 

ingredient) 

MRID and 

Classification 

Acute Toxicity 

Classification 

Seedling 

Emergence 

(Tier II) 

850.4100 

Dicot – Lettuce 

(Latuca sativa) 

CGA-362622 

75.2% a.i. (TEP) 

NOAEC = 0.0007 lbs 

a.i./acre 

EC25 = 0.0006 lbs 

a.i./acre 

Endpoint: Shoot dry 

weight 

45371734 

Acceptable -- 

Monocot – 

Ryegrass 

(Lolium perenne) 

CGA-362622 

75.2% a.i. (TEP) 

NOAEC = 0.0014 lbs 

a.i./acre 

IC25 = 0.0019 lbs 

a.i./acre 

Endpoint: Shoot dry 

weight 

45371734 

Acceptable -- 

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

2 Acute Oral (avian/mammal): Based on LD50 (mg/kg) <10 very highly toxic; 10-50 highly toxic; 51-500 moderately 

toxic; 501-2000 slightly toxic; >2000 practically nontoxic 

3

 Based on acute contact LD50 (μg a.i./bee) <2 highly toxic; 2-10.99 moderately toxic; ≥11 practically non-toxic 4

 However, there was a statistically significant increase in number of eggs cracked/eggs laid at 54 mg a.i./kg, but not 

at 106 or 201 mg a.i./kg. 

Effects of Trifloxysulfuron-sodium on Plant Reproduction 

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 vegetative vigor guideline (850.4150) 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) so further data are 

not requested at this time. 

Degradate Toxicity 

Six effects studies on two degradates of trifloxysulfuron-sodium are available. Each of the two 

degradates (CGA-382997 and CGA-368732, both of which do not retain the SU bridge) has 

three studies, one each on rainbow trout, Daphnia, and green algae (see Table 11). The data 

indicate that these degradates are likely equally (given that all endpoints are non-definitive for 

fish and daphnia) or less toxic (to the green algae) than the parent is. For example, comparing the 

only definitive endpoints available for the green algae indicates that the degradate CGA-368732 

is far less toxic (EC50: 23 mg a.i./L; MRID 45371729) than is the parent (EC50: 0.0065 mg a.i./L) 
27 

to this organism. Additional data on the remaining degradates of trifloxysulfuron-sodium are not 

available to supplement these data, even though some of the remaining transformation products 

are also generated by degradation of other sulfonylurea herbicides (i.e., CGA-53052 [ADMP] 

and CGA-294409; see Table 9). Furthermore, the degradates, CGA-368733 and 436664, were 

not included in the HED residues of concern because of their much lower mobility (Koc values: 

875-22817 ml/goc and 650-1925 ml/goc, respectively, see Table 8). Given the available data, 

degradates with an intact sulfonyl urea bridge (-NH-CO-NH-SO2-) will be considered as part of 

the total toxic residues (NOA-440735 and CGA-292230) and not assessed individually. 

Additional comparison of actual and ECOSAR 1.1 calculated toxicity endpoints indicate that 

several degradates may be more toxic to freshwater fish and invertebrates (NOA-436664, CGA246186, NOA-440735, and CGA-368733) than is the parent compound (see Appendix D). 

However, upon comparison of ECOSAR-generated endpoints for these degradates (from 0.95 to 

31 mg/L) to a GENEEC-generated peak EEC (0.0046 mg/L), under the assumption of no 

degradation of the parent, at a single application rate of 0.028 lb a.i./A applied 3x with a 14 day 

interval, and an average Kd of 0.595mL/g, the peak EEC is far less than 5% (i.e., the aquatic 

listed species LOC) of the calculated endpoint concentrations (0.01 to 0.5%). Therefore, with the 

exception of NOA-440735 (which contains the SU bridge), the remaining degradation products 

will not be considered in risk assessment explicitly and no additional degradate data will be 

recommended. 

Ecological Incidents 

A search of the Ecological Incident Information System (EIIS) database showed one “Possible” 

(I015713-081) and one “Probable” (I020283-014) trifloxysulfuron incident affecting turf from 

ground, broadcast applications of Monument 75 WG, and impacting 0.5 acre from direct 

treatment (registered use) and 35 acres from carryover (unknown legality of product use), 

respectively, in South Carolina. 

In the Incident Data System (IDS) database, registrants reported 1 aggregate plant damage 

incident (015713-00112) associated with trifloxysulfuron-sodium use (Envoke emulsifiable 

concentrate, Reg. No. 100-1132) between November 1, 2003 and October 31, 2004. 

A search of the Avian Incident Monitoring System (AIMS) database did not provide any 

additional incident data. 

6. EXPOSURE PATHWAYS OF CONCERN 

The environmental fate properties of trifloxysulfuron-sodium indicate that direct spray, spray drift, 

leaching to groundwater, and runoff represent potential transport mechanisms. These pathways 

may result in a wide range of potential aquatic and terrestrial exposure scenarios. 

The conceptual model used to depict the potential ecological risk associated with the use of 

trifloxysulfuron-sodium and degradates (the stressors) assumes that as a pesticide, 

trifloxysulfuron-sodium can adversely affect terrestrial and aquatic organisms (the receptors) if 

environmental concentrations exceed toxic thresholds as a result of application according to the 

label directions. Ecological receptors that may potentially be exposed to trifloxysulfuron-sodium 
28 

and degradates include terrestrial and semi-aquatic wildlife (e.g., mammals, birds, terrestrialphase amphibians and reptiles), terrestrial and semi-aquatic plants, and terrestrial invertebrates 

(e.g., honey bees). Additionally, given the mobility of trifloxysulfuron-sodium and degradates, 

aquatic organisms (i.e., freshwater and estuarine/marine fish and invertebrates, aquatic-phase 

amphibians, and aquatic plants) are potential receptors in adjacent water bodies through off-site 

transport of trifloxysulfuron-sodium from the application site through runoff, erosion, and spray 

drift. 

The results of running the SIP and STIR models are presented in APPENDIX B and 

APPENDIX C, respectively. While the SIP model suggests that there are potential concerns for 

both mammals and birds from exposure via drinking water, the model does not perform well 

with chemicals that have a high aqueous solubility and have low toxicity to these organisms. 

Furthermore, the acute effects endpoints were based on non-definitive endpoints, which implies 

low toxicity to birds and mammals; the chronic endpoints for these taxa were definitive. This 

route of exposure is not likely to be significant enough to cause concern. The analysis with STIR 

indicates low likelihood of risk to birds or mammals through inhalation of trifloxysulfuronsodium. 

7. ANALYSIS PLAN 

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

be estimated. The use pattern, environmental fate, and ecological effects of trifloxysulfuronsodium will be characterized and integrated to assess the risks. This will be accomplished using 

a risk quotient (ratio of exposure concentration to effects concentration) approach. Although risk 

is often defined as the likelihood and magnitude of adverse ecological effects, the risk quotientbased 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 trifloxysulfuron-sodium may be 

estimated using the probit dose-response slope and either the level of concern (discussed below) 

or the actual calculated risk quotient value. 

Ecological Risk Assessment 

Measures of Exposure 

In order to estimate risks of trifloxysulfuron 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 

trifloxysulfuron are discussed on OPP’s model website.6

 

 

 

6

 http://www.epa.gov/opp00001/science/models_pg.htm 
29 

Aquatic Exposure 

Models used for drinking water and aquatic exposure estimates include: PRZM (Pesticide Root 

Zone Model) and EXAMS (EXposure Analysis Modeling System), PRZM-Groundwater (GW) 

and SCI-GROW. The modeling of drinking water and aquatic exposure will use the total toxic 

residue approach (TTR) in order to include both parent and degradation products. 

The Health Effects Division (HED) determined that the residues of concern in drinking water are 

parent trifloxysulfuron-sodium, CGA-053052, CGA-382997, and CGA-3687337

. For the 

ecological assessment, EFED will use the total toxic residues including the parent 

trifloxysulfuron-sodium, and two other sulfonyl urea degradates, CGA-292230, and NOA440735, on the basis of ECOSAR 1.1 effects data comparisons (see Appendix D). EFED will 

use standard available models8

 to evaluate potential exposure to pesticides in surface water 

(PRZM and EXAMS), and ground water (PRZM-GW) and SCI-GROW sources as described at 

http://www.epa.gov/pesticides/science/models_db.htm. The versions used by the Agency at 

the time the risk assessment is completed will be used in the assessment. Because the earlier 

drinking water assessment (Table 5) for parent trifloxysulfuron and the degradates CGA-053052, 

CGA-382997, and CGA-368733 did not include modeling using PRZM-GW (i.e., the assessment 

predates the availability of the model), the drinking water assessment will be updated following 

current guidelines. 

The drinking water and aquatic exposure assessments will also include available surface and 

ground water monitoring data from Federal, State, and other sources with consideration of 

changes in use patterns that may have occurred. 

These sources include: 

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

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

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

(NAWQA) Program Data Warehouse 

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

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

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

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

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

Terrestrial Exposure 

Exposure to terrestrial organisms will use the following models: AgDrift, AgDisp, T-REX, and 

TerrPlant. The terrestrial exposure assessments will consider the parent, trifloxysulfuronsodium, as well as the two sulfonyl-urea degradate/transformation products, CGA-292230, and 

 

 

8 PRZM and EXAMS are Tier II models used to estimate environmental exposure concentrations in surface water. A 

description of these models and the guidelines for selecting input parameters can be found at 

http://www.epa.gov/oppefed1/models/water/
30 

NOA-440735, on the basis of ECOSAR 1.1 effects data comparisons (see Appendix D). The 

approach assumes comparable toxicity due to closely related chemical structure. The degradates 

will not be considered individually. 

Measure of Effects 

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

Data are typically obtained from registrant-submitted studies or from literature studies identified 

by ECOTOX. The ECOTOX database provides more ecological effects data in an attempt to 

bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data and 

potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX 

was created and is maintained by the USEPA, Office of Research and Development, and the 

National Health and Environmental Effects Research Laboratory's Mid-Continent Ecology 

Division. 

Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects to determine the 

potential ecological risk from the use of pesticides and the likelihood of direct and indirect 

effects to non-target organisms in aquatic and terrestrial habitats. For the assessment of risks, the 

risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are 

divided by acute and chronic toxicity values. The resulting RQs are then compared to the 

Agency’s Levels of Concern (LOCs) (USEPA 2004). These criteria will be used to indicate 

when trifloxysulfuron use, as directed on the label, has the potential to cause adverse direct or 

indirect effects to non-target organisms. In addition, incident data from the EIIS, IDS, and AIMS 

will be considered as part of the risk characterization. Degradates will be considered within the 

context of a total toxic residues approach and not assessed individually. 

8. ENDANGERED SPECIES ASSESSMENTS 

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

Agency will evaluate exposure and potential risks to federally listed threatened and/or 

endangered (listed) species from registered uses of pesticides in registration review. The process 

for evaluating potential risks to listed species is further described at 

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

9. ENDOCRINE DISRUPTOR SCREENING PROGRAM 

Trifloxysulfuron-sodium 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/. 

 
31 

10. PRELIMINARY IDENTIFICATION OF DATA GAPS 

Environmental Fate 

Table 13 identifies the environmental fate studies submitted by the registrant, as well as study 

classifications and whether or not additional data are needed in order to support the registration 

review exposure assessments. Rationale for the additional data requested is also presented. 

Table 13. Submitted Environmental Fate Data for Chemical Trifloxysulfuron-Sodium and Degradates 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

needed to 

conduct risk 

assessment?

Comments 

835.2120 Hydrolysis 45371804 

45371805 Acceptable No 

835.2240 Aqueous 

photolysis 

45371806 

45371807 Acceptable No

835.2410 Soil photolysis 45371808 

45371809 Acceptable No

835.4100 Aerobic soil 

metabolism 

45371810 

45371811 Acceptable No Data are adequate for Total Toxic 

residue methods. 

835.4200 Anaerobic soil 

metabolism 

No data 

submitted - Noa

While anaerobic soil metabolism data 

are required according the 40 CFR 

158.1300, these data are not typically 

used in exposure modeling as it is not 

expected to have a significant influence 

on estimates of residues in surface 

water. In the absence of these data, it 

will be assumed that no anaerobic 

degradation occurs (i.e., degradates are 

stable); however, these data may help to 

refine exposure assessments. 

835.4300 Aerobic aquatic 

metabolism 

45371814 

45371815 Acceptable No Data are adequate for Total Toxic 

residue methods 

835.4400 

Anaerobic 

aquatic 

metabolism 

45371812 

45371813 Acceptable No Data are adequate for Total Toxic 

residue methods 

835.1230 

835.1240 

Adsorption/ 

desorption and 

leaching 

Parent 

45371817 

45371818 

45371825 

Degradates 

- 

45371821 

45371823 

45371820 

45371824 

45371816 

Acceptable 

Acceptable No

Trifloxysulfuron-Sodium 

Column leaching 

Aged column leaching 

Batch equilibrium 

Degradates 

Batch equilibrium 

CGA-382997 

CGA-53052 

CGA-368732 

CGA-368733 

NOA-436664 

835.1410 Volatility – 

laboratory 

No data 

submitted Waived No Waiver Request November 7, 2002 

DP D284113 
32 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

needed to 

conduct risk 

assessment?

Comments 

835.6100 Terrestrial field 

dissipation 

45371827 

45371828 

45371829 

Acceptable No

Long-term desorption 

Louisiana 

California 

850.6100 Analytical 

method in soil 45371831 No 

835.6200 Aquatic field 

dissipation 

No data 

submitted - No No aquatic uses. 

850.6100 Analytical 

method in water 

47534701 

47534702 Yes Submitted no independent lab evaluation 

165-4 

(850.1730) 

Fish 

bioconcentration Waived Waiver Request November 7, 2002 DP D284114 a

 Not required but may be helpful if exposure concentrations for drinking water require 

refinements. 

Effects 

Table 14 and Table 15 identify the ecological effects studies, as well as study classifications 

and whether or not further data are needed in order to support risk assessment. Rationale for the 

additional data requested is presented below the tables. 

Table 14. Submitted Aquatic Ecological Effects Data for Trifloxysulfuron-sodium and its Degradates

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct 

risk 

assessment? 

Comments 

 850.1010 Freshwater 

invertebrate 

acute toxicity 

45371716 Acceptable 

No 

45371717 

CGA-382997 Acceptable 

45371730 

CGA-368732 Acceptable 

850.1025 

850.1035 

850.1045 

850.1055 

Saltwater 

invertebrate 

acute toxicity 

45371719 Acceptable 

45371718 Acceptable No 

 

 850.1075 Freshwater 

fish acute 

toxicity 

45371713 Acceptable 

No 

45371714 Acceptable 

45371715 

CGA-382997 Supplemental 

45371731 

CGA-368732 Acceptable 

 850.1075 Saltwater fish 

acute toxicity 

45371720 Acceptable No 
33 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed to 

conduct 

risk 

assessment? 

Comments 

 850.1300 Freshwater 

invertebrate 

life cycle 

45371722 Acceptable No 

 850.1350 Saltwater 

invertebrates 

life cycle -- -- No 

A majority of the available fish and 

invertebrate studies indicate low 

toxicity of trifloxysulfuron to these 

taxa; the value of these additional data 

to the ecological risk assessment is 

likely low. 

 850.1400 Freshwater 

fish 

early-life stage 

45371721, 

45893302 Supplemental No 

-- 

 850.1400 Saltwater fish 

early-life stage 

-- -- No 

A majority of the available fish and 

invertebrate studies indicate low 

toxicity of trifloxysulfuron-sodium to 

these taxa; the value of these additional 

data to the ecological risk assessment is 

likely low. 

 850.1500 Fish life cycle 

-- -- No 

A majority of the available fish and 

invertebrate studies indicate low 

toxicity of trifloxysulfuron-sodium to 

these taxa; the value of these additional 

data to the ecological risk assessment is 

likely low. 

850.4400 Aquatic plant 

growth: 

Tier II 

vascular plants 

45371723 Supplemental 

No 

45371802 Acceptable 

850.4500 Aquatic Plant 

Growth: 

Tier II algae 

45371724 Acceptable 

No 

45371725 Acceptable 

45371729 

CGA-368732 Supplemental 

45371726 Acceptable 

45371727 

CGA-382997 Supplemental 

850.1735 

850.1740 

Whole 

Sediment 

Testing 

-- -- No 

 
34 

Table 15. Submitted Terrestrial Ecological Effects Data for Trifloxysulfuron-sodium

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

risk 

assessment? 

Comments 

 850.2100 Avian oral 

toxicity 

45371707 Acceptable 

No 

Although EPA does not have acute 

oral toxicity data on a passerine 

species, based on the available toxicity 

data, risk to passerine species is 

unlikely to exceed levels of concern. 

45371708 Acceptable 

 850.2200 Avian dietary 

toxicity 

45371709 Acceptable No 

45371710 Acceptable 

 850.2300 Avian 

reproduction 

45371711 Acceptable 

No 

45371712 Acceptable 

Nonguideline Avian 

inhalation -- -- No 

 850.3020 Honey bee 

acute contact 

toxicity 

45371728 Acceptable No 

 Honey bee 

acute oral 

toxicity 

-- -- No 

850.3030 Honey bee 

residue on 

foliage 

-- -- No 

 850.3040 Field testing 

for pollinators -- -- No 

850.4100 Terrestrial 

plant toxicity: 

Tier II 

seedling 

emergence 

45371734 Acceptable No 

850.4150 Terrestrial 

plant toxicity: 

Tier II 

vegetative 

vigor 

45371734 Acceptable No 

Additional effects information that would be useful to the Agency include ecological incidents 

(non-target plant damage and avian, fish, reptilian, amphibian and mammalian mortalities) not 

already reported to the Agency. 

References 

USEPA, 2008. Trifloxysulfuron-Sodium: Human Health Risk Assessment for the 

Requested Use on Sports Fields and Residential Turfgrass. Health Effects Division. DP 

Barcode 352260. November 12, 2008.
35 

APPENDIX A. STRUCTURES, CHEMICAL NAMES, and ABBREVIATIONS 
36 
37 
38 
39 

APPENDIX B 

 SIP ANALYSIS 

Table 1. Inputs 

Parameter Value 

Chemical name Trifloxysulfuron 

Solubility (in water at 25°C; mg/L) 25700 

 

Mammalian LD50 (mg/kg-bw) 15.4 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Mammalian NOAEL (mg/kg-bw) 78.8 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Avian LD50 (mg/kg-bw) 2250 

Avian test species mallard duck 

Body weight (g) of "other" avian species 

Mineau scaling factor 

 

Mallard NOAEC (mg/kg-diet) 106 

Bobwhite quail NOAEC (mg/kg-diet) 201 

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 

 

Table 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 4420.4000 4420.4000 

Adjusted toxicity value (mg/kg-bw) 11.8451 60.6099 

Ratio of exposure to toxicity 373.1847 72.9320 

Conclusion* 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Table 3. Avian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 20817.0000 20817.0000 

Adjusted toxicity value (mg/kg-bw) 177750.0000 5.2589 

Ratio of exposure to acute toxicity 0.1171 3958.4085 

Conclusion* 

Exposure through drinking 

water alone is 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. 
40 

APPENDIX C 

STIR Analysis Results 

Input 

Application and Chemical Information 

Enter Chemical Name Trifloxysulfuron 

Enter Chemical Use turf/lawn 

Is the Application a Spray? (enter y or n) y 

If Spray What Type (enter ground or air) ground 

Enter Chemical Molecular Weight (g/mole) 459.3329 

Enter Chemical Vapor Pressure (mmHg) 9.75E-09 

Enter Application Rate (lb a.i./acre) 0.079688 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 2250 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 1.58 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 15.4 

Enter Lowest Rat Inhalation LC50 (mg/L) 0.04 

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) 2.41E-04 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.03E-05 

Adjusted Inhalation LD50 2.35E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.29E-06 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 8.42E-03 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 3.59E-04 Exposure not Likely Significant 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.41E-04 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.81E-05 

Adjusted Inhalation LD50 2.38E+00 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.60E-05 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 1.06E-02 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 4.44E-03 Exposure not Likely Significant 
41 

APPENDIX D: Ecotoxicity data (where available) and ECOSAR 1.1 Output for 

Parent (CGA-362622) and degradates (CGA-382997, CGA-368732, CGA-53052, CGA294409, CGA-368733, NOA-436664, CGA-292230, CGA-246186, NOA-440735 (M9)) 

Degradate Eco data ECOSAR data 

Organism/MRID Endpoint Organism/Chemical Endpoint* 

CGA-362622 

(Parent) 

Trout/45371713 LC50 >103 mg a.i./L FW Fish/amides LC50: 815.9 mg/L 

 FW Fish/sulfonyl ureas LC50: 190.5 mg/L 

 FW Fish/neutral organic LC50: 2283 mg/L 

 Daphnia/45371716 EC50 >108 mg a.i./L Daphnid/amides LC50: 348.5 mg/L 

 Daphnid/sulfonyl ureas LC50: 248 mg/L 

 Daphnid/neutral organic LC50: 1019.4 mg/L 

 Green algae/45371725 EC50: 0.0065 mg 

a.i./L 

Green algae/amides EC50: 15 mg/L 

 Green algae/sulfonyl ureas EC50: 0.243 mg/L 

 Green algae/neutral organic EC50: 940.6 mg/L 

CGA-382997 Trout/ 45371715 LC50 >96.7 mg a.i./L FW Fish/halo ether-acid LC50: 61,253 mg/L 

FW Fish /neutral organic LC50: 1.4 x 105 mg/L 

 Daphnia/ 45371717 EC50 >99.5 mg a.i./L Daphnia/halo ether-acid3 LC50: 10,997 mg/L 

 Daphnia/neutral organic LC50: 53,651 mg/L 

 Green algae/45371727 EC50 >95.85 mg a.i/L Green algae/neutral organic EC50: 5,813 mg/L 

CGA-368732 Trout/ 45371731 LC50 >104 mg a.i./L FW Fish /substituted urea LC50: 12.44 mg/L 

FW Fish /amide LC50: 4.63 mg/L 

FW Fish /halo ether LC50: 19.8 mg/L 

FW Fish /neutral organic LC50: 23.52 mg/L 

 Daphnia/ 45371730 1EC50 >119 mg a.i./L Daphnia/substituted urea LC50: 17.3 mg/L 

 Daphnia/amide LC50: 4.1 mg/L 

 Daphnia/halo ether LC50: 5.59 mg/L 

 Daphnia/neutral organic LC50: 15.85 mg/L 

 Green algae/45371729 2

EC50: 23 mg a.i/L Green algae/substituted urea EC50: 0.201 mg/L 

 Green algae/amide EC50: 0.36 mg/L 

 Green algae/neutral organic EC50: 11.6 mg/L

CGA-53052 N/A N/A FW Fish /aniline (unhindered) LC50: 119 mg/L 

FW Fish /neutral organic LC50: 1,115 mg/L 

 Daphnia/aniline (unhindered) LC50: 1.135 mg/L 

 Daphnia/neutral organic LC50: 483.3 mg/L 

 Green algae/aniline 

(unhindered) 

EC50: 3.14 mg/L 

 Green algae/neutral organic EC50: 446 mg/L 

CGA-294409 N/A N/A FW Fish/substituted urea LC50: 618 mg/L 

 FW Fish/amides LC50: 1090 mg/L 

 FW Fish/neutral organic LC50: 3,057 mg/L 

 Daphnia/substituted urea LC50: 529 mg/L 

 Daphnia/amides LC50: 324 mg/L 

 Daphnia/neutral organic LC50: 1,236mg/L 

 Green algae/substituted urea EC50: 15 mg/L 

 Green algae/amides EC50: 12 mg/L 

 Green algae/neutral organic EC50: 1,137mg/L 

CGA-368733 N/A N/A FW Fish/neutral organic LC50: 16.36 mg/L 

 Daphnia/neutral organic LC50: 10.5 mg/L 

 Green algae/neutral organic EC50: 10.5 mg/L 

NOA-436664 N/A N/A FW Fish/phenols LC50: 13.52 mg/L 

 FW Fish/neutral organic LC50: 56.12 mg/L 

 Daphnia/phenols LC50: 6.3 mg/L 

 Daphnia/neutral organic LC50: 34.2 mg/L 

 Green algae/phenols EC50: 27 mg/L 

 Green algae/neutral organic EC50: 32 mg/L 
42 

Degradate Eco data ECOSAR data 

Organism/MRID Endpoint Organism/Chemical Endpoint* 

CGA-292230 N/A N/A FW Fish/amides LC50: 816 mg/L 

 FW Fish/sulfonyl ureas LC50: 190.5 mg/L 

 FW Fish/neutral organic LC50: 2283 mg/L 

 Daphnia/ amides LC50: 348.5 mg/L 

 Daphnia/ sulfonyl ureas LC50: 247.7 mg/L 

 Daphnia/neutral organic LC50: 1019.4 mg/L 

 Green algae/amides EC50: 15 mg/L 

 Green algae/ sulfonyl ureas EC50: 0.243 mg/L 

 Green algae/neutral organic EC50: 940.6 mg/L 

CGA-246186 N/A N/A FW Fish/anilines LC50: 401.4 mg/L 

FW Fish/poly phenols LC50: 96.3 mg/L 

FW Fish/ phenol amines LC50: 31 mg/L 

 FW Fish/neutral organic LC50: 5669 mg/L 

 Daphnia/ anilines LC50: 0.95 mg/L 

 Daphnia/ poly phenols LC50: 1626 mg/L 

Daphnia/ phenol amines LC50: 1.5 mg/L 

 Daphnia/neutral organic LC50: 2079 mg/L 

 Green algae/ anilines EC50: 4.17 mg/L 

Green algae/ poly phenols EC50: 12 mg/L 

Green algae/ phenol amines EC50: 15 mg/L 

 Green algae/neutral organic EC50: 1907 mg/L 

NOA-440735 (M9) N/A N/A FW Fish/aliphatic amines LC50: 1169.8 mg/L 

 FW Fish/imides LC50: 131 mg/L 

FW Fish / amides LC50: 5564.5 mg/L 

 FW Fish/ sulfonyl ureas LC50: 573.6 mg/L 

FW Fish/ neutral organic LC50: 15,643 mg/L 

 Daphnia/ aliphatic amines LC50: 118 mg/L 

 Daphnia/ imides LC50: 7.9 mg/L 

 Daphnia/ amides LC50: 1147 mg/L 

 Daphnia/ sulfonyl ureas LC50: 956 mg/L 

 Daphnia/neutral organic LC50: 5722 mg/L 

Green algae/ aliphatic amines EC50: 152.5 mg/L 

 Green algae/ imides EC50: 0.163 mg/L 

 Green algae/ amides EC50: 36.33 mg/L 

 Green algae/ sulfonyl ureas EC50: 0.28 mg/L 

 Green algae/neutral organic EC50: 5248 mg/L 1

 5% mortality in 2nd highest dose 2

 Cell density most sensitive endpoint 

3

 Acid moiety: Predicted values multiplied by 10 

*FW fish value estimates from test duration of 96 hours, daphnia 48 hours, and green algae 96 hours.