### UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF

CHEMICAL SAFETY AND POLLUTION PREVENTION



### PC Code: 129009

DP Barcode: D414506



### MEMORANDUM

DATE:

SUBJECT:

FROM:

TO:

Through: March 12,2014

Tier I Drinking Water Assessment for the proposed Section 3 ALS inhibition

tolerant sorghum crops new use for the chemical Rimsulfuron (P.C. Code: 129009,

DP Barcode 414506) /() •

1 __



### Michael Barrett, Senior Chern· 

# (In

# n~;yi 'f

Environmental Risk Branch V

# ~ -j

# ~ e 

### Environmental Fate and Effects Division (7507P)

Kable Davis, Risk Manager (RM-25)

Daniel Kenny, Risk Manager Reviewer

Herbicide Branch Registration Division (7505P)

Meheret N egussie, Risk Assessor

Christine Olinger, Chief Registration Action Branch 3

Health Effects Division (7509P) ' 

### J 

# //3// 

# J

Mah Shamim, Ph.D, Chief

# ~ Environmental Risk Branch V

Environmental Fate and Effects Division (7507 P)

Enclosed is the Tier I drinking water assessment for the proposed Section 3 new uses of

rimsulfuron for sorghum crops tolerant to the inhibition of the acetolactate synthase (ALS)

enzyme.



### 1

### 2



## Executive Summary

The impact of rimsulfuron ( 1

- (4 , 6

- Dimethoxypyrimidin

- 2

- yl)

- 3

- (3

- ethylsulfonyl

- 2

- pyridylsulfonyl) urea) residues of concern (also referred to as the “total toxic residues”) was addressed in order t o evaluate the impact of a proposed new use on ALS inhibition tolerant sorghum. This assessment replaces previous drinking water assessments since two environmental degradation products have been added to the residues of concern for human exposure.

Rim sul furon belongs to the sulfonyl urea class of herbicides, which acts by inhibiting the plant enzyme acetolactate synthetase (ALS). The inhibition of this enzyme blocks the production of amino acids, valine and isoleucine, which are important in the producti on of plant proteins and other components. This leads to the disruption of cell division and elongation in the plant. It is intended to control a variety of annual and perennial grass and annual broadleaf weeds in both agricultural and non

- agricultural s ettings such as barnyardgrass, crabgrass, foxtail, panicum, volunteer wheat, Johnson grass and shattercane

. The application of rimsulfuron to ALS inhibition tolerant crops will enable for rimsulfuron to treat these crops without damage while killing other target weeds. The new use for ALS inhibition tolerant sorghum crops is proposed for DuPontTM

Resolve ® and DuPontTM Steadfast® (see Table 2 in the Use Characterization section )

.

T his Tier I Drinking Water Assessment for the proposed new use of rimsulfuron on ALS inhibition tolerant sorghum crops pro vides estimates of the upper bound residue concentration of

rimsulfuron total toxic residues (parent and the IN

- 70941 and IN

- 70942 degradates in surface and ground water drinking water sources resulting from its proposed uses. The tier 2 model

PRZM/EXAMS (PRZM v ersion 3.12.2, May 2005 and EXAMS v ersion 2.98.4.6, April 2005) is

used to evaluate surface water exposure . T he T ier 1 model PRZM

- GW (version 1.0 , December 2012) is used to evaluate ground water exposure. Rimsulfuron existing water monitoring data is also cited, however there are no data for the rimsulfuron degradates of concern to verify modeled exposures for drinking water.

Rimsulfuron foliar applications using ground and aerial sprays impact both surface and ground water drinking water sources g iven that it possesses similar physical chemical properties and persistence to other chemicals which are known to translocate to these media. Rimsulfuron degrades mainly in sequence to degradates IN

- 70941 and IN

- 70942

– both of these molecules

maintain a contracted form of the sulfonylurea bridge . IN

- 70942 only slowly degrades over a period of months or years under most environmental conditions. Since IN

- 70941 and IN

- 70942 are expected to possess similar environmental fate and toxicity to parent rimsulfur on for the purposes of human health risk assessment, these degradates are included in the drinking water

assessment.

In this updated drinking water exposure assessment it has been determined that exposure from the current and proposed uses should not exc eed 22.2 μg/L (ppb ) for acute exposure and 19.7 μg/L (ppb) for chronic and cancer exposure. These values reflect a predicted higher potential exposure level from groundwater sourced drinking water supplies than surface water supplies . The Table 1

### 3

values are based on uses from several crop sites with higher single and seasonal maximum application rates than is proposed for the new use on ALS inhibition tolerant sorghum.

Table 1

. Maximum Tier I Rimsulfur on ROC EDWCs for drinking water based on application of rimsulfuron to crops with highest rates and exposure potential.

Crops / Uses Represented Highest Daily Value (Acute) Post

- Breakthrough Average (Chronic and Cancer)

All 

## 22.2 19.7

Based upon the h ighest values from six standard Tier 1 groundwater scenarios (i.e., a WI scenario based upon a predominantly corn production area, see also Table 12 for more detailed results. The EDWCs are representative for crop use sites with

h igher allowed application rates than for the proposed use on ALS inhibition tolerant sorghum.

The estimated drinking water concentrations (EDWCs) in this assessment are additionally higher than in previous assessments because of the addition of two deg radation products to the total toxic residues (TTR )

– also known as the residues of concern 1



### . The TTR includes parent rimsulfuron, plus the IN

- 70941, and IN

- 70942 degradates

. The EDWCs for groundwater and surface water sourced drinking water specific to t he proposed new use are discussed later in this document but only the values in Table 1 should be used for a conservative estimate of the drinking water contribution to dietary exposure estimates.



## Use Characterization

Rimsulfuro n is applied pre

- emergent or post

- emergent for weed control in various crop / non

- crop

uses via ground (broadcast and banded applications) and aerial applications. Rimsulfuron formulated products are available as an emulsifiable concentrate (field corn us e only), water dispers i ble granules (dry flowable), or soluble concentrates (solid). Maximum single application

rates for the various crop and non

- crop use sites range between 0.0078 and 0.0625 lbs. a.i./A. In many cases the labels are not specific with regards to the maximum number of applications or application intervals per year for a particular use site.

Rimsulfuron herbicide is used for control of many broadleaf and grass weed species (primarily

pre

- and early post

- emergent) on numerous crop and non

- agricultural use sites

1 B oth terms (TTR and ROC) in this document are used to represent the residues assessed to determine drinking water

exposure.

### 4

The proposed use is for two formulations of rimsulfuron water soluble granular applied via conventional ground or aerial foliar applications on ALS inhibition tolerant sorghum crops. This new use is proposed for DuPontTM Resolve ® ( 2 5 percent rim sulfuron) and DuPontTM Steadfast® ( 1 5 percent rim sulfuron) products

. Proposed maximum application rates range between 0.012 lbs.

a.i./A

– 0.03 1 lbs. a.i./A with seasonal maximum application rates ranging between 0.0 16

– 0.0 31

lbs. a.i./A with a minimum of 7 seven days between applications specified on the draft product

label. Table 1 shows the complete proposed use information for rimsulfuron on ALS inhibition tolerant sorghum crops.

Table 2

. Summary of application information based on labels provided by DuPontTM for rimsulfuron related to the proposed Section 3 new use for ALS inhibition tolerant sorghum crops.

PRODUCT % A.I. FORMULATION APPLICATION

METHOD SINGLE APP.

RATE (lbs. a.i./A) MAX.

SEASONAL

APP. RATE (lbs. a.i./A) MIN.

RETREATMENT

INTERVAL (d ays)



### DuPontTM

Resolve®

(352

- 768) 25 SG G,A 0.0156

- 0.0313 0.0313 7



### DuPontTM

Steadfast®

(352

- 816) 15 SG G,A 0.0117

- 0.0157 0.0157

. 7

1. Formulation identifier: SG = Water soluble granule

2. Application method identifiers: G = f oliar ground application; A = foliar aerial application



### Sorghum crop production is highly concentrated over an area of the country confined to mainly the

Southern Great Plains region including Central and West Texas, the Panhandle of and Central Oklahoma, Central and Western Kansas, S outh Central Nebraska, and South Central South

Dakota. Figure 1 below shows a map of the density of sorghum crops planted nationwide by county from th e United States Department of Agriculture’s National Agricultural Statistics Service (USDA NASS).

### 5

Figur e 1

. . Recent distribution of sorghum crops planted nationwide ( ca. 2012).

Map Citation: United States Department of Agriculture National Agricultural S tatistics Service http://www.nass.usda.gov/Charts_and_Maps/Crops_County/pdf/AS

- PL12

- RGBChor.pdf



## Environmental Fate a nd Transport Characterization

Properties of Parent and Degradates of Concern

Physical and chemical properties of rim sul furon are shown in Table 3 below. Environmental fate and transport properties of rim sulfuron based upon registrant submitted studies or other references

are shown in Table 4 below.

Table 3

. Nomenclature and physicochemical properties of rimsulfuron.

Parameter Value Reference

Chemical Classification Pyrimidinyl Sulfonylurea Registrant

Data and

PPDB 1 Molecular Formula C 14 H 17 N 5 O 7 S 2

PC Code 12 9009

Chemical Name (IUPAC) 1

- (4,6

- dimethoxypyrimidin

- 2

- yl)

- 3

- (3

- ethylsulfonyl

- 2

- pyridylsulf onyl)urea

### 6

Parameter Value Reference

Chemical Name (CAS) N

- [[(4,6

- dimethoxy

- 2

- pyrimidinyl)amino]carbonyl]

- 3

- (ethylsulfo nyl)

- 2

- pyridine sulfonamide

CAS Number 122931

- 48

- 0

Pesticide Clas sification Herbicide

MRIDs

413563

- 01 Molecular Weight 431.44

Physical State Solid

pKa 4

Water Solubility (ppm) Parent 7,300 @ pH 7/25 o C ; 135 ppm @ pH 5; 5,560 ppm @ pH 9

IN

- 70941 0.7 @ pH 7/25 o C

IN

- 70942 0.2 @ pH 7/25 o C

Vapor pre ssure (25 o C) 1.1x10 - 8 torr

- Equal to 1.447x10
- 11 atm

Henry's Law Constant 1.40x10 - 12 atm. m 3

. mole
- 1 (Calculated)

Octanol/Water Partition, K

ow 1 @ pH7 and 87 @ pH 5 (log K OW 0.034 @ pH7 &1.94 @ pH 5)

1 PPDB = Pesticide Properties Database or Footp rint database. URL: 

### http://sitem.herts.ac.uk/aeru/iupac/Reports/586.htm

Table 4

. A summary of the environmental fate data for rimsulfuron.

Parameter Value MRID

Hydrolysis t 1⁄2 = 4.5

- 4.7days @ 25 o C, pH 5;

t 1⁄2 = 7.1

- 7.3days @ 25 o C, pH 7;

t 1⁄2 = 4.2

- 10.9Hours @ 25 o C, pH 9.

Major degradates (from contraction of the sulfonylurea bridge):

IN

- 70941 and IN

- 70942, IN

- 70942 appears to be stable at pH 7. Minor degradates (from cleavage of the sulfonylurea bridge): IN

- E9260

and IN

- J290 and IN

- T5831 (only @ pH 5). 413563

- 33, Acceptable

Direct photolysis in

water at pH 7 Half

- lives in irradiated samples (11.0

- 12.4 days) were longer than the dark controls (6.4

- 6.5 days) su ggesting that Direct photolysis is NOT an important degradation pathway

.

Major and Minor degradates : Similar to hydrolysis although irradiation was associated with reduced conversion of the transformation product IN

- 70941

into IN

- 70942 and/or enhanced deg radation of IN

- 70942. Formation of

IN

- E9260, IN

- J290, and the un

- identified polar compounds appeared to be

enhanced. No evidence of photolysis of IN

- 70942 (the terminal toxic residue for human health risk assessment). 419316

- 08, Acceptable

### 7

Parameter Value MRID

Photolysis on

soil Half

- lives in irradiated/dark control samples were in the range of 11

- 12 days indicating that photolysis on soil is NOT an important degradation pathway

.

Major and Minor degradates : Similar to hydrolysis although irradiation appeared to increase the formation of soluble un

- identified polar compounds. 419316

- 09, Acceptable

Aerobic soil

metabolism t 1⁄2 = 21.3 days for two labels (R 2 = 0.87

- 0.94; separate tests done with

pyrimidine and pyridine labeled parent) in Sassafras sandy loam soil from

Penns Grov e, NJ (Sand= 77%, Silt= 14%, Clay 9%, pH 6.7, Organic matter= 1.1%, CEC= 3.2 meq/100 g). TTR (rimsulfuron + IN

- 70941 + IN

- 70942) t 1⁄2 = 484.8 days at 25 C.

t 1⁄2 = 21.5 days for two labels (R 2 = 0.95) in Traver sandy loam soil from Madera, CA (Sand= 53%, Silt= 28%, Clay 19%, pH 7.4

– 7.5, Organic matter= 1.7%, CEC= 19.1 meq/100 g).

TTR t 1⁄2 = 1960.8 days at 20 C, 1386.4 days at 25 C.

t 1⁄2 = 48.1 days for two labels (R 2 = 0.82) in Arkansaw sandy loam soil from Arkansaw, WI (Sand= 76%, Silt= 16%, Clay 8%, pH 6.8

– 7.3 , Organic matter= 3.7 %, CEC= 13.7 meq/100 g).

TTR t 1⁄2 = 214.5 days at 20 C, 151.7 days at 25 C

Major degradates (from contraction of the sulfonylurea bridge):

IN

- 70941 further degrading into IN

- 70942) plus IN

- E9260 (from cleavage of the sulfonylurea bridg e; only quantified in one of the three test soils)

Minor degradates (from cleavage of the sulfonylurea bridge): IN

- J290 and

IN

- T5831. 41356334: Acceptable

48332003:

In review

Anaerobic aquatic

metabolism t 1⁄2 = 4.2 days for combined labels (R 2 = 0.98; n ote separate results for

pyrimidine and pyridine labeled product are available from this study) in Farm pond in Mississauga, Ontario, Canada (sediment classified as a loam with Sand=44%, Silt= 30%, Clay 26%, pH 7.6, Organic matter= 5.4%, CEC= 29.2 meq/100 g), at 25 C. TTR (rimsulfuron + IN

- 70941 + IN

- 70942) t 1⁄2 = 58.3 days at 25 C Major degradates were identified:

IN

- 70941 (most persistent, up to 43

- 45% of applied at 7 to 14 days after treatment) and the subsequently formed IN

- 70942 which was up to 10

- 12% at 30 DAT but declined rapidly thereafter. 48332004, In

Review

Anaerobic soil

metabolism t 1⁄2 = 17.9

- 18.1 days range for two labels (R 2 = 0.91

- 0.99) in Sassafras sandy

loam soil from Penns Grove, NJ (same soil used in the aerobic soil study).

Major/Minor deg radates: Same as the aerobic soil. 41356335, Acceptable

### 8

Parameter Value MRID

Aerobic aquatic

metabolism t 1⁄2 =0.5

- 2 Days at 25 o C in the water column;

t 1⁄2 = 59

- 77 Days at 5 o C in the water column. (No indication of sediment included in study.)

At 25 C IN

- 70942 was 65% of appli ed rimsulfuron and constituted essentially all of the remaining residues.

Important Note: Calculated half

- lives might NOT represent an aerobic aquatic system because of exposure to light and the use of extremely diluted sediment; but note that photolysis has not been found to be a major dissipation pathway Also, a newer study is currently under review. Major/Minor degradates: Similar to hydrolysis.

Rimsulfuron appears to be slightly more persistent with half

- lives of a few days in two test systems (study still in review.) Preliminary results for TTR degradation: Blackiston, DE loam system t 1⁄2 = 273.4 days Hampshire, UK sand system t 1⁄2 = 39.1 days 43288502, Supplemental

(45490802:in review)

Adsorption/ Desorption (K d and

K

oc in L Kg
- 1 ) [Pyri midine

- 2

- 14 C]:

Cecil sandy loam (NC): K d = 0.23 and K

oc = 19 Fargo clay loam (ND): K d = 1.36 and K

oc = 55 Sassafras sandy loam (NJ): K d = 0.32 and K

oc = 55 Flanagan silt loam (IL): K d = 1.52 and K

oc = 61 ( Limited data also available on som e degradates; please refer to Table 6

the “Environmental Fate” section of this Problem Formulation document.)

See Table xxx for details on degradate sorption coefficients. 41356336, Acceptable

Terrestrial

Field/ Lysimeter Dissipation 1 Greenville, MS: t 1⁄2 = 09 Days (average in the top 0

- 3”)

Madera, CA: t 1⁄2 = 08 Days (average in the top 0

- 3”) Rochelle, IL: t 1⁄2 = 18 Days (average in the top 0

- 3”) Newark, DE: t 1⁄2 = 05 Days (average in the top 0

- 3”)

Maj or degradates: IN

- 70941 (degrading into IN

- 70942) Minor degradates: None identified as the bridge

- cleavage degradates may have fallen below the LOD (LOD≤10% of the applied) 419316

- 06,

419316

- 10, Acceptable

Bioconcentration in Fish: Waived following reque st (MRID 413563

- 39) due to low K

ow =1 at pH7.

1 The terrestrial field dissipation study for a soil in Newark, Delaware submitted under MRID 419316

- 10 was upgraded to acceptable.



## Environmental Fate Summary

In the natural environment, the major route s of d issipation of rimsulfuron are expected to be hydrolysis and / or bio

- transformation. A dditionally, a dsorption/desorption studie s suggest that rimsulfuron may be highly mobile and vulnerable to run

- off and leaching ( K
oc 

### ranged from 19

- 74

### 9

L Kg - 1 

### ). Therefor e, the chemical may enter aquatic systems via run

- off and erosion. Although there is a potential for rimsulfuron parent to reach groundwater when conditions promote its stability and relatively rapid subsurface transport, it is also true that its persisten ce is relatively low compared to most pesticides which have been commonly detected in groundwater. The soil mobility / leachability of the primary degradates IN

- 70941 and IN

- 70942 is somewhat less than for parent rimsulfuron ( Table 6 ) but these compounds are more environmentally persistent than parent rimsulfuron. Significant leaching was not confirmed in th e field dissipation studies but it is uncertain whether residues that may have leached could be confirmed give n the sampling methods and detection limits of the analytica l methods.

Rimsulfuron is expected to transform/degrade into a number of products under different environmental conditions. The two consistently major degradates for rimsulfuron result from

cont raction of the sulfonylurea

- bridge (IN

- 70941 and IN

- 70942). A third major degradate (in one aerobic soil metabolism study only) results from cleavage of the sulfonylurea bridge (IN

- E9260) (an aminopyrimidine degradate, IN

- J290, is formed from the remainde r of the cleaved molecule and, while reported as a major degradate for some other sulfonylurea herbicides, is not major for rimsulfuron). Full chemical names are provided in Table 5 (IN

- J290 is not included becaus e it is not part of the residues of concern

. T he minor degradates are cleavage degradates (IN

- J9260 in systems other than aerobic soil, IN

- J290 and IN

- T5831). Note that In

- J290 is an aminopyrimdine compound that is also a degradation product of several ot her registered sulfonylurea herbicides. Mobility of the transformation products/degradates were evaluat ed by thin layer chromatography (TLC ) and results indicate high mobility to IN

- E9260 and high to medium mobility for IN

- 70941,

IN

- 70942 (this persistent degradate had highly variable estimated mobility between the test soils)

and IN

- J290 ( Table 6 ). Solubility was reported for only IN

- 70941 and IN

- 70942 and was 0.7 ppm for the first and 0.2 ppm for the second. The se solubilities are four orders of magnitude smaller than for the parent compound. Considering quantities formed and relative persisten ce of transformation products/degradates , all are expected to reach aquatic systems in varied

concentrations. In additio n, most of the parent that reaches aquatic systems by drift is expected to transform under aerobic conditions by hydrolysis into (the usually) transient IN

- 70941 then into the usually persistent IN

- 70942 (only in the single biologically active anaerobic aq uatic test system did IN

- 70942 degrade substantially) . The time line for this event is expected to be as

follows: IN

- 79041 at the short to medium

- term (because it transforms into IN

- 70942),

IN

- 70942/IN

- E9290/In

- J290 at the medium to long

- term. IN

- 70942 is expected to be the terminal and persistent degradate under aerobic conditions but transforms further into multiple unidentified minor polar products under anaerobic conditions (≤10% AR)

.

Table 5

. Rimsulfuron transformation produc ts/degradate code/chemical names.

Applicant's

Code IUPAC Chemical Name

IN

- 70941 N

- (4, 6

- Dimethoxy

- 2

- pyrimidinyl)

- N

- ((3

- ethylsulfonyl)

- 2

- pyridinyl))Urea

IN

- 70942 N

- ((3

- Ethylsulfonyl)

- 2

- pyridinyl)

- 4, 6

- dimethoxy

- 2

- pyrimidineamine)

IN

- E9260 3

- (Ethylsulfony l)

- 2

- pyridine sulfonamide

IN

- J290 2

- Amino

- 4, 6

- dimethoxy pyrimidine

IN

- T5831 N

- (4, 6

- Dimethoxy

- 2pyrimidinyl) Urea

### 10

Table 6 . Mobility of parent rimsulfuron and its transformation products/degradates (K

oc 

### values).



## Environmental Transformation Products of Rimsulfuron and the
Residues of C oncern

Details of rimsulfuron degradation in the environment are discussed in the Rimsulfuron Registration Review Problem F ormulation (EFED, 9/13/2012; DP Barcode D401380).

For the purposes of this exposure assessment the relevant environmental degradation pathway is:

Parent Rimsulfuron > IN

- 70941 > IN

- 70942

This pathway was observed in hydrolysis, aerobic soil metabolism, aerobic and anaerobic aquatic metabolism, and field dissipation studies. In most cases it is the initial and primary for transformation of rimsulfuron. Chemical nomenclature and identity information are provided in 

### Table 3

.

Ri msulfuron Degradates of concern: Ad/Des Metho d 1 TLC Method 2

Parent Parent IN

- 70941 IN

- 70942 IN

- E9260 IN

- J290

Cecil sandy loam 19 51 58 41 44 284
Fargo clay loam 55 63 357 317 6 ND 3

Sassafras sandy loam 55 41 79 207 110 ND
Flanagan silt loam 61 74 142 1,398* 6 834
Woodstown sandy loam ND ND ND ND ND 393
Keyport silt loam ND ND ND ND ND 362
Mobility Class 4 Very high

- High High

- Medium (except *=Low) Medium

1 K d calculated from a 4

- hour/4 concentrations adsorption/desorption experiments; results from MRID 41356336

. 2 K d calculated from R f values using Hamaker equation; 3 ND= No Data; results from MRID 41356337

. 4 Mobility class as per: McCall, et al. 1980. Estimation of chemical mobility in soil from liquid chromatographic

retention times. Bull. Environm en tal Contamination. Toxicology. 24, 190

- 195.

### 11

Table 7

. Structures and names of rimsulfuron and degradates of concern for drinking water

exposure.



## Rimsulfuron [DPX

- E9636]

IUPAC Name: 1

- (4,6

- Dimethoxypyrimidin

- 2

- yl)

- 3

- (3

- ethylsulfonyl

- 2

- pyridyls ulfonyl)urea.

CAS Name: N

- [[(4,6

- Dimethoxy

- 2

- pyrimidinyl)amino]carbonyl]

- 3

- (ethylsulfonyl)

- 2

- pyridines

ulfonamide.

CAS Number: 122931

- 48

- 0

SMILES String: CCS(=O)(=O)c1cccnc1S(=O)(=O)NC(=O)Nc2nc(OC)cc(OC)n2 ( EpiSuite 4.0).

Empirical formula: C 14 H 17 N 5 O 7 S 2 Molecular formula: C 14 H 17 N 5 O 7 S 2 Molecular weight: 431.44



## IN

- 70941

IUPAC Name: 1

- (4,6

- Dimethoxypyrimidin

- 2

- yl)

- 1

- (3

- ethylsulfonyl

- 2

- pyridyl)urea (IUPAC

Name).

CAS Name: N

- (4,6

- Dimethoxy

- 2

- pyrimidinyl)

- N

- ((3

- (ethylsulfonyl)

- 2

- pyridinyl))urea.

CAS Number: 138724

- 53

- 5

SMILES String: COC1=NC(=NC(=C1)OC)N(C(=O)N)C2=NC=CC=C2S(=O)(=O)CC

Molecular wt: 367.39

### 12



## IN

- 70942

IUPAC Name: N

- (3

- Ethylsulfonyl

- 2

- pyridyl)

- 4,6

- d i methoxy

- pyrimidin

- 2

- amine

. CAS Name: N

- ((3

- (Ethylsulfonyl)

- 2

- pyridinyl)

- 4,6

- dimethoxy

- 2

- pyrimidineamine.

CAS Number: 151331

- 80

- 5

SMILES String: C1=C(N=C(N=C1OC)NC2=NC=CC=C2S(=O)(=O)CC)OC

Molecular wt: 324.36

SMILES Strings were retrieved from the CAS numbers at: http://cactus.nci.nih.gov/chemical/structure

### 13



## Derivation of Degradate Properties for Drinking Water Exposure

Prediction

There are limited physical

- chemical or environmental fate data which have been submitted by registrants or available from the open literature for the degradates discussed above including for

IN

- 70941 and IN

- 70942

. P hysical chemical property values for these metabolites were estimated

from EPISuite 2



### . . 

### Table 5 shows the predicte d and measured (where available) properties of the

IN

- 70941 and IN

- 70942 degradates compared to those of parent rim sulfu ron ( from studies submitted to the Agency )

. Since IN

- 70942 is the terminal and most persistent degradate in the

residues of concern its properties are especially relevant to a total toxic residue analysis for the

rimsulfuron drinking water exposure assessment. While all three moieties are weakly to moderately sorbed to soil and sediment materials IN

- 70942 is measurably more strongly partit ioned onto organic material or clay minerals with K

oc 

### or K foc 

### values generally between 200 and 300 ml/g

.

Table 8

. Comparison of physical chemical properties of rimsulfuron degradation products to parent rimsulfuron.

Property/

EPISuite

Estimator Program Value from

Existing

Database EPISuite Value and/or measured value

Rimsulfuron Rimsulfuron IN

- 70941 1 IN

- 70942 1 Other

IN

- 70942 1

measured
Molecular Weight 431.4

--- 367.38 324.36

--- Solubility in Water (25 °C, mg/L) (WSKOW v . 1.41) 7300 @ pH 7

135 @ pH 5 270 28.59 133.6

---

Vapor Pressure (25 °C, mm Hg) (MPBPVP v. 1.43) 1.1x10 - 9 1.13x10 - 8 7.69x10

- 12 4.23x10 - 9

---

Henry’s Law Constant (25 °C,

atm·m 3 /mol) (HENRYWIN v. 3.20) 1.40x10 - 12 2.33 E - 16 2.33E - 13 2.36x10 - 9

---

Octano l

- Water

Partition Coeff. (Log K

ow ) (WSKOW v. 1.41) 0.034 @pH7 1.94 @pH5 0.029 @ pH 7 2.61 2.31

---

Soil

- Water Partition

Coeff

. (K

oc , ml/g) (KOCWIN v. 2.00) 47 (median)

55 (mean) --- 13.9 (MCI estim.) 1061 (Kow 28.2 (MCI estim. )

58 9.6 (Kow

estim .) K foc 145

– 223;

median 204 in 4

soils

2 EPISuite (Estimation Programs Interface Suite) version 4.0 was used. EPI Suite is a software developed by the EPA Office of Chemical Safety and Pollution Prevention in collaboration with the Syracuse Research Corporation (SRC). EPISuite is a collection of programs which estimate physical chemical and environmental fate propert ies for mainly organic compounds.

### 14

Table 8

. Comparison of physical chemical properties of rimsulfuron degradation products to parent rimsulfuron.

Property/

EPISuite

Estimator Program Value from

Existing

Database EPISuite Value and/or measured value

Rimsulfuron Rimsulfuron IN

- 70941 1 IN

- 70942 1 Other

IN

- 70942 1

measured
estim.) 110 (TLC meas.) 262 (TLC meas.) Germany DAR (7/2/03)

1 Degradates incorporated in the Drinking water residues of concern

. Rim sulfuron and IN

- 70942 physical chemical property values generally agreed well with estimat es from EPISuite. Other literature cited: Rapporteur Member State Germany. 2005. Draft Assessment Report (DAR): Rimsulfuron; second stage of the review programme referred to in Article 8(20 of Council Directive 91/414/EEC.

### 15



## Problem Formulation

The envi ronmental fate properties of the rim sulfuron total toxic residues / residues of concern

indicate that drinking water exposure potentially may occur in surface water supplies or in drinking water wells. Direct deposition of rimsulfuron from aerial applicat ions and subsequent

washoff from crop foliage , runoff, leaching, and spray drift deposition are potential transport

mechanisms to surface and ground water

. The potential for rimsulfuron TTR exposure in surface and ground drinking waters also exists b ase d on the high persistence of the rimsulfuron TTR and high mobility in the environment . Therefore, this drinking water assessment will address scenarios which depict the potential for rim sulfuron to be transported off

- site to drinking water

sources

.

As pe r meeting with the Health Effects Division’s Risk Assessment Branch 3 (meeting dated

December 17 , 201 3 ) the residues of concern for drinking water include parent rim sulfuron and all major degradates which maintain the original or a contracted form of the s ulfonylurea bridge between the pyridine and pyrimidinyl moieties of rimsulfuron (the other identified degradation products not included in this assessment arise form the cleavage of this bridge and therefore only consist of a either a pyrimidine or pyridin e derivative) . These include degradates identified as

IN

- 70941 and IN

- 70942

. Table 4 in t he previous section indicated that these degradates were detected at significant levels (greater than 10 percent of applied) in soil , sediment

, and water.

T hese degradates possess similar physical chemical properties and are being considered to be of equal toxicity for the purposes of a human dietary exposure assessment for rimsulfuron

. Therefore,

the total residue method wi ll be used to estimate exposure in drinking water sources. In est imated drinking water concentra tions (EDWCs) using the total residue method, degradate residues from environmental fate laboratory studies were added to the parent rim sulfuron to calculate t he total

residue half

- life. This approach assum es that degradates possess equivalent toxicity and fate properties to the parent active ingredient. An overview of the total residue method is provided in the white paper on the FIFRA SAP Meeting on, “Select ed Issues Associated with the Risk Assessment Process for Pesticides with Persistent, Bioaccumulative, and Toxic Characteristics” held in October 2008 (EPA, 2008).



## E xposure Analysis

Methods for Estimation of Drinking Water Concentrations

In this Tier I analysis, 1

- in

- 10 year peak concentrations are representative of acute levels of exposure, the 1

- in

- 10 year annual average concentration are representative of chronic levels of exposure, and the 30

- year mean concentration is assumed to represent cancer dri nking water exposure from surface drinking water sources. In ground water, estimated peak concentrations are assumed to represent acute exposure concentrations and the post

- breakthrough average (generally

### 16

a multi

- year exposure value) estimated concentrati ons are assumed to represent chronic and cancer

concentrations.

Estimated drinking water concentrations ( EDWCs ) in surface waters are estimated using the Tier 2 model PRZM/EXAMS (PRZM version 3.12.2, May 2005 and EXAMS version 2.98.4.6, April 2005). PR ZM/EXAMS is publically available on

- line at http://www.epa.gov/oppefed1/models/water/#przmexamsshell

. The index reservoir scenario simulating inflow and pesticide transport from s treams into a reservoir intake is simulated for the drinking water assessment. Crop and regional specific p ercent crop areas (PCAs) are accounted for in EDWCs specific to each crop to factor in the portion of watersheds that are typically subject to pesti cide loadings and subsequent transport to water bodies. The guidance, “Development and Use of Percent Cropped Area and Percent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update”, are used to determine PCA values for each cro p (EPA, 2012).

Ground water estimates of concentrations are estimated using the PRZM

- GW (version 1.0, December 2012) will be used to evaluate ground water exposure. PRZM

- GW is publically

available on

- line at http://www.epa.gov/oppefed1/models/water/#przm_gw

. Results from the long

- standing tier I SCI

- GROW model (Screening Concentration in GRound Water model, Version 2.3, May 16, 2006) will also be shown in comparison with the PRZM

- GW mod eling results according to EFED guidance related to the evaluation period for the recent release of

PRZM

- GW . SCI

- GROW is publically available on

- line at http://www.epa.gov/oppefed1/models/wa ter/#scigrow

.

The fate parameter s and use

- specific input parameter s for the surface water modeling are shown in

Table 9 (for parent rimsulfuron and Table 10 (for the rimsulfuron TTR or residues of con cern). Parameters for the groundwater modeling of the TTR are provided in Input values for the groundwater modeling are summarized in Table 11

. Aerial applications are only evaluated in this Tier 1 drinking water assessment since this is considered to be the application type resulting in the

most conservative (highest) exposure scenario. Representative PRZM/EXAMS input and output files are provided in Appendix A and B

.

### 17

Table 9

. PRZM

- EXAMS (PE5) in put parameters for modeling drinking water exposure to parent rimsulfuron.

Input Parameter Value* Reference

APPLICATION DETAILS



### Application Rate (lb a.i./Acre) 0.0 31 (One Application) Equal to the m aximum label rate for single and annual periods. 

### ( See proposed and existing product

l abel s ) Application Intervals (days) NA

Application Dates June 5 (1 st 

### run) and June 25 (2 nd 

### model run) Represents variability between a

preemergent and postemergent application

Percent Crop Area 0. 91 Default national valu e for all agricultural land. See:
http://www.epa.gov/oppefed1/models/ water/pca_adjustment_dwa.html



### Wetted In? No Product Label . CAM = 2 used for PRZM input.

Depth of Incorporation (inches) 0

Method of Application Aerial

CHEMICAL AND FATE PROPERTIES



### Molecular Weight 431.44 Value for parent rimsulfuron

Vapor Pressure 1.1x10 - 8 torr 

### Value for parent rimsulfuron

Solubility in Water (ppm) 7 3 00 MRIDs: 419316

- 02 and 413563

- 01.

Partition Coefficient “K OC 

### ” (L/Kg) 47.5 Average value for parent rimsulfuron ( MRID 41356336)

Aerobic Soil Metabolism

Half

- life (days) 44.8 days Determined by taking the 90% upper

bound C.I. value for the mean

half

- life of Parent in 3 test soils.

(MRID 41356334 and 48332003)

Aerobic Aquatic Metabolism

Half

- life (days) In an altern ative approach, the value was not used and hydrolysis half

- lif

e at pH 7 was entered. This input value is a

zero rate under the assumption the hydrolysis is the dominant transformation process in the simulated reservoir

.

### 18

Table 9

. PRZM

- EXAMS (PE5) in put parameters for modeling drinking water exposure to parent rimsulfuron.

Input Parameter Value* Reference



### A na erobic Aquatic Metabolism

Half

- l ife (days) 4.2 MRID 48332004.

Hydrolysis Half

- life @ pH 7 (days) 7.2 Average value at pH 7. (MRID

413563

- 33)
Direct Aqueous Photolysis

Half

- life(days) Stable The h alf

- lives of parent rimsulfuron

in dark were less than in i rradiated samples (MRID 419316

- 08)

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



### Table 10

. PRZM

- EXAMS (PE5) input parameters for modelin g drinking water exposure to

rimsulfuron TTR (residues of concern) from sorghum new use and from all registered uses

.

Input Parameter Value* Reference

APPLICATION DETAILS

Application Rate (lb a.i./Acre) 0.031 (One Application)
For sorghum new use.

0.06 25 for all new uses. Equal to the m aximum label rate for single and annual periods. 

### ( See proposed and existing product

l abel s ) Application Intervals (days) NA



### Application Dates June 5 (1 st 

### run) and June 25 (2 nd 

### model run) Represents variability between a

preemergent and postemergent application

Percent Crop Area 0. 91 Default national value for all agricultural land. See:
http://www.epa.gov/oppefed1/models/ water/pca_adjustment_dwa.html

Wetted In? No Product Label. CAM = 2 used for PRZM input.

Depth of Incorporation (inches) 0 

### Labels
Method of Application Ae rial

### 19

Table 10

. PRZM

- EXAMS (PE5) input parameters for modelin g drinking water exposure to

rimsulfuron TTR (residues of concern) from sorghum new use and from all registered uses

.

Input Parameter Value* Reference

CHEMICAL AND FATE PROPERTIES

Molecular Weight 324.36 Value for IN

- 70942, the terminal

residue of concern.

Vapor Pressure (torr) 1.1x10
- 8 Default to value for parent rimsulfuron

, all of the TTR have low volatility.

Solubility (mg/L) 134 Value for IN

- 70942 at pH 7 and 25 C.

Partition Coefficient “K OC ” (L/Kg) 262 Median (lower than avg. value) for

IN

- 70942, the terminal degradate in the residues of concern (MRID 41356336). Outside (not revi ewed by EFED) data

indicates that K

oc or K foc values near 200 to 300 in soil may be common

– see 

### Table 8 .)

Aerobic soil Metabolism Half

- life (days) 1526 Determined by taking the 90% upper

bound C.I. value for the mean half

- life

o f Parent + IN

- 70941 +IN

- 70942 in 3

test soils.

(MRID 41356334 and 48332003)

Aerobic Aquatic Metabolism

Half

- life (days) In an alternative approach, the value was not used and hydrolysis

half

- live was entered 3

.
Aerobic Aquatic Metabolism

Half

- life (days) Z ero rate used for this

simulation

.

(517 tentative value.) Data are preliminary, study in review.

Model run with the more conservative

value of a zero rate.
Preliminary half

- life determined by taking the 90% upper bound C.I. value

for the mean half

- life o f Parent +

IN

- 70941 +IN

- 70942 in 2 test soils.

(MRID: 45490802.)

Anaerobic Aquatic Metabolism

Half

- life (days) 174.9 Per Input Guidance, used 3 x the single

measured half

- life of 58.3 days for

rimsulfuron TTR.

MRID 48332004.

3 In two test soils calculated half

- lives were 273 and 39 days for the rimsulfuron TTR in the2 test systems (MRIDs 43288502 and 45490802) . 90% upper bound confidence interval of the mean is 517 days as a model input. An alternative approach, given the high variability in aerobic soil metabolism rates, is to use the hydrolysis rate of

IN

- 70942 at pH 7. This rate is zero.

### 20

Table 10

. PRZM

- EXAMS (PE5) input parameters for modelin g drinking water exposure to

rimsulfuron TTR (residues of concern) from sorghum new use and from all registered uses

.

Input Parameter Value* Reference

Hydrolysis Half

- life @ pH 7 ( days) 0 rate

(no hydrolysis) No evidence of IN

- 70942 hydrolysis at pH 5 to 9 in available study (MRID 41356333). PMRA(PRVD2008

- 06) reports that a separate study shows

IN

- 70942 to be stable over 30 days at pH 5, 7, and 9.

Direct Aqueous Photolysis

Half

- li fe(days) 0 rate
(no photolysis) The half

- lives of parent rimsulfuron in

dark were less than in irradiated samples (MRID 419316

- 08) , no evidence of photolysis of IN

- 70941 and

IN

- 70942 available.

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



### Table 11

. PRZM

- GW input parameter values for physical chemical and fate properties used for rimsulfuron TTR (residues of concern in groundwater sourced drinking water.

PRZM/EXAMS Input

Parameter Input Value and Unit Source

Pesticide Properties

Hydrolysis Half

- life @ pH 7 (days) 0

(no hydrolysis) No evidence of IN

- 70942 hydrolysis at pH 5 to 9 in available study (MRID 41356333). PMRA(PRVD2008

- 06) reports that a separate study

shows IN

- 70942 to be stable over 30 days at pH 5, 7, and 9.


### Aerobic (top) soil metabolism (t 1/2 

### ) 1526
(also an input for

SCI

- GROW) Determined by taking the 90% upper bound C.I. value for the

mean half

- life of Parent +

IN

- 70941 +IN

- 70942 in 3 test

soils.

(MRID 41356334 and 48332003)

### 21

Table 11

. PRZM

- GW input parameter values for physical chemical and fate properties used for rimsulfuron TTR (residues of concern in groundwater sourced drinking water.

PRZM/EXAMS Input

Parameter Input Value and Unit Source

Soil

- Water Partition Coefficient (K

oc 

### ) (mL/g) 262
(also an input for

SCI

- GROW) Median (lower than avg. value) for IN

- 70942, the terminal degradate in the

residues of co ncern (MRID 41356336). Outside (not reviewed by EFED) data

indicates that K

oc or K foc values near 200 to 300 in soil may be common.)


### Application Methods and Crop Management Input Parameters Crop Scenario and Weather WI Sands

w14920 (La Crosse, WI) All PRZM screening scenarios run including Delmarva, FL Citrus, FL Potato, Georgia Coastal, and NC Coastal. WI

Sands scenario maximum exposure scenario and shown in this report. 

### Application Rate

Lb ai/A 0.031 (One Application)
For sorghum new use.

0.0625 for all new uses.
(also an input for

SCI

- GROW) Equal to the maximum label rate for single and annual periods.



### Application Date June 25 Represents a relatively late season application for sorghum

and most use sites. PRZM

- GW results are usually not highly dat e sensitive except for certain

non

- persistent pesticides that are

more stable in subsurface

horizons. 

### Number of Applications and

Retreatment Interval Single application per

year. Maximum single and annual application rates are the same (product labels)



### A pplication Methods Ground application Most conservative application method for leaching to groundwater

### 22



## Exposure Modeling Results

Table 12 and Table 13 show the groun d water and surface water sourced drinking water exposure estimates. Initially both the groundwater and surface water scenarios were run to represent the propose use rates on ALS inhibition tolerant sorghum. The highest estimates were from the

Wisconsin “c orn” groundwater scenario for both acute and chronic exposure (by convention, when groundwater impacts are assessed, a standard set of 6 scenarios are run to provide a conservative estimate of exposure, regardless of the crop site being evaluated). Subsequ ently the Wisconsin scenario was rerun for the TTR or residues of concern to represent exposure potential from the highest rimsulfuron application rate for all uses. Based on this the screening concentration that should be used in drinking water contribut ions to dietary exposure are 22.2 for acute and 19.7 for

chronic or cancer risk assessments. By contrast, f or the proposed use on sorghum PRZM

- GW model estimates upper

- bound concentrations of in ground drinking water sources are 12.2 μg/L (ppb) for acute e xposure and 11.0 μg/L (ppb) for chronic and cancer exposure ( Table 12 )

. Lower EDWCs for the sorghum new use are predicted for surface water supplies: modeling using PRZM/EXAMS predicts that the concentrations of rimsulfuron, IN

- 70941, and IN

- 70942 in surface drinking water sources are not likely to exceed 1. 38 μg/L (ppb) for the acute peak concentration, and 0.38 μg/L (ppb) for the chronic and cancer concentration ( Table 13 )

. Again,

PRZM

- GW estimates wer e subsequently run to estimate the highest expected exposure levels

from all uses (i.e., to represent several crops with higher use rates than the proposed new use) and only the higher values in bold text ( Table 12 ) should be used to represent the drinking water contribution to dietary risk assessment.

Finally, it should be noted that the predicted chronic exposures for the residues of concern is considerably higher than for residues of parent rimsulfuron alone ( Table 13 ), demonstrating that the degradation products provide the dominant component to chronic exposure.

Table 12

. PRZM

- GW and SCI

- GROW estimated upper bound concentrations in ground water (ppb) for rimsulfuron and degr adates of concern including IN

- 70941

and IN

- 70942.

Crops (scenario) Highest Daily Value (Acute) Post

- Breakthrough Average (Chronic and Cancer)

ALS inhibition tolerant sorghum (FL citrus) 7.33 6 .0

Sorghum (WI corn) 12.4 11.3

All uses (WI corn) 

## 22.2 19.7

Sorghum (DE corn) 7.29 5.97

### 23

Table 12

. PRZM

- GW and SCI

- GROW estimated upper bound concentrations in ground water (ppb) for rimsulfuron and degr adates of concern including IN

- 70941

and IN

- 70942.

Crops (scenario) Highest Daily Value (Acute) Post

- Breakthrough Average (Chronic and Cancer) Sorghum (NC cotton) 8.63 6.96

(GA peanut) 3.49 3.15 (FL potato) 4.19 3.65

SCI

- GROW 2.3 0.49 0.49
FL, WI, DE, NC, and GA scenarios are standard for PRZM

- GW Tier 1. Highest acute and chronic DWECs for sorghum new use a nd all existing uses are

bolded

.

Table 13

. Maximum Tier I / II r imsulfuron parent and ROC EDWCs for drinking water sourced

from surface and ground waters based on the proposed application of rimsulfuron to sorghum. *

Use/Rate Modeled: ALS tolerant sorghum, at a rate of 0.0 31 lbs. a.i./A

Chemical Maximum PRZM/EXAMS Surface water EDWC (ppb) Maximum PRZM

- GW Ground

water Acute/Chronic EDWC (ppb)

Acute Value Chronic/Cancer

Value Acute Chronic



### Rimsulfuron Parent 1.08 0.019 NA NA

Rimsulfuron ROC (residues of concern) 1.38 0.380 12.2 11.0



## Exposure Characterization

Although the modeled groundwater concentrations for the TTR (residues of concern) at the Tier I level were much higher than the modeled surface water concentrations it is important to understand what these concentrations represent. The highest groundwater exposure values were obtained from modeling scenarios of some of the most highly vulnerable shallow aquifers in the

United States. For example, the Wisconsin ground water scenario where the highest exposure was estimated in an area of sand soils overlying an aquifer 30 feet below the land surface. These do not represent the concentrations that may occur in a large majority of the US agricultural and noncrop

land use areas were both weather and soil characteristics result in much lower concentrations of

### 24

pesticides reaching groundwater. Furthermore, the concentrations represent the potential exposure level for drinking water wells tapping shallow aquifers and directly located in these vulnerable areas. Most of the predicted chronic exposure is expected to be to IN

- 70942 which is the terminal residue in the residues of concern definition and is much more persistent in the environment than parent rimsulfuron. Further con sideration of additional refinements or scenario development representative of rim sulfuron applications to sorghum crops is possible, if needed.

In addition to the high persistence of IN

- 70942 another factor contributing to the increased estimated exposur e potential to the TTR (compared to parent rimsulfuron) is the apparent

resistance of IN

- 70942 to hydrolysis leading to an assumption of no hydrolysis in the modeling. This can significantly increase the EDWCs from groundwater modeling in particular compar ed to a similar chemical which undergoes (even slow) hydrolysis in long

- term simulations. By comparison, parent rimsulfuron is rapidly hydrolyzed in the environment with even more rapid hydrolysis under alkaline conditions (half

- life of several hours) in p articular ( Table 4 ). Additional

data on the environmental fate data such as directed IN

- 70942 metabolism and hydrolysis studies might allow further refinements of modeling inputs which could lead to lower exposure estimates.



## Mon itoring Data Analysis

Rimsulfuron monitoring data found from stream water, spring water, and ground water sources are not yet available for the United States Geological Survey National Water Quality Assessment (USGS NAWQA) program as it has only recently been considered for addition to the analyte

schedule . Monitoring data from NAWQA are available on

- line at: http://infotrek.er.usgs.gov/nawqa_queries/index.jsp

No monitoring studies coul d be located for the rimsulfuron degradates included in the residues of concern. Kreuger and Adielsson ( 2008 ) 4 

### reported rimsulfuron at concentrations of 0.01 to 0.21 ug/L in <1% of samples collected from four streams associated with light rimsulfuron us e intensity (i.e., less than 2% of the watershed treated) It was estimated that the maximum percent of applied rimsulfuron appearing in the stream water was 1.79% from 5 years of sampling at 3 sites and 9 years of sampling at a 4 th 

### site. Much of the differ ence between these observed concentrations and modeled parent concentrations in this risk assessment can be attributed to differences in the actual use intensity and the use intensity levels that must be assumed for the risk assessment.

A monitoring stud y from Quebec (for parent rimsulfuron only) has been reported in a Proposed

Re

- evaluation Decision by Health Canada 5 

### as follows :

Four rivers situated in agricultural regions of Quebec that predominantly grow corn (20

– 36.5% of cropped area) and soya (5.6

– 1 3.2% of cropped area) were sampled three times weekly from the

4 Ekohydrologi 103 Uppsala 2008. Avdelningen för vattenvårdslära. Swedish University of Agricultural Sc iences, Division of Water Quality Management. ISRN SLU

- VV

- EKOHYD

- 103

- SE; ISSN 0347

- 9307

5 Pest Management Regulatory Agency, Health Canada . 2008. Pr oposed Re

- evaluation Decision dated January 29, 2008 (PRVD2008

- 06).

### 25

middle of May to the middle of August in the years 2002, 2003, and 2004. Rimsulfuron was detected in 2.6% to 14.3% of the samples analyzed. The maximum concentration of rimsulfuron

detected was in one sample at a concentration of 1.0 mg a.i./L (LOD 0.06 μg a.i./L).



### These data have not been received or reviewed by EFED.



## Uncertainties and Limitations

There are two main areas of uncertainty with regards to the modeling of rimsulfuron residues of

concern: (1.) The extent of the representativeness of the most vulnerable areas modeled to actual drinking water supplies in rimsulfuron current or future use areas. (2.) Limitations on the data for model input regarding the fate of rimsulfuron degradates

included in the residues of concern. Hydrolysis, aerobic soil metabolism, aerobic aquatic, and anaerobic aquatic metabolism studies were all terminated before substantial decline

was observed of IN

- 70942 and sometimes also of IN

- 70941. In most studies (not includi ng the hydrolysis study) , levels of these degradates were observed to level off several sampling period before study termination allowing calculation of a TTR half

- life but with less certainty than if more substantial decline of the “terminal” degradate IN

- 70942 had

been observed



## References

F IFRA SAP Final Meeting Minutes 2008. Transmittal of Meeting Minutes of the FIFRA Scientific Advisory Panel Meeting Held October 28

- 31, 2008 on Selected Issues Associated with

the Risk Assessment Process for Pestici des with Persistent, Bioaccumulative, and Toxic

Characteristics. http://www.epa.gov/scipoly/sap/meetings/2008/october/minutes.pdf

USEPA. 2002. Guidance for Selecting Input P arameters in Modeling the Environmental Fate and Transport of Pesticides. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division. Feb. 28, 2002. Online at: http://www.epa.gov/oppefed1/models/water/input_guidance2_28_02.htm

.

U.S. Enviro nmental Protection Agency 2012

.. Development and Use of Percent Cropped Area

and Pe rcent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update. EPA Office of Pesticide Programs. Washington, DC.

USEPA. 2013. Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift . U.S.

Environmental Protectio n Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division. Dec. 20 , 2013.

### 26

### 27



## Appendix A

– Surface Water Modeling Supporting

Documentation

PRZM/EXAMS (PE5 Shell) Modeling File ( Rimsulfuron Total Toxic Residues)

stored as RimsTTR_KSsorg_Rsvr2

- aer0625.out

Chemical: Rimsulfuron TTR PRZM environment: KSsorghumSTD.txt modified Tueday, 29 May 2007 at 12:55:46

EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 05:14:08

Met file: w13996.dvf modified Wedday, 3 July 2002 at 09:04:44 Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.8062 0.7913 0.7434 0.6492 0.5957 0.2313

1962 0.6804 0.6684 0.623 0.574 0.5437 0.3026

1963 1.237 1.213 1.122 0.9 663 0.8695 0.4126

1964 0.7963 0.7825 0.7287 0.6545 0.5975 0.3442

1965 1.309 1.289 1.23 1.058 0.9528 0.4678

1966 0.7308 0.7183 0.6667 0.5885 0.5571 0.3309

1967 0.5235 0.5142 0.4827 0.4225 0.398 0.24

1968 1.458 1.438 1.379 1.209 1.108 0.4836

1969 0.6005 0.59 07 0.5732 0.5221 0.4771 0.3354

1970 0.5312 0.5249 0.4925 0.4303 0.3943 0.2288

1971 0.4563 0.4483 0.4185 0.3671 0.3353 0.2177

1972 0.5527 0.5429 0.5186 0.4777 0.4427 0.2281

1973 1.438 1.412 1.31 1.135 1.023 0.4585

1974 0.6968 0.6843 0.6359 0.6063 0.5644 0.3 708

1975 0.4106 0.4039 0.3788 0.3361 0.312 0.2282

1976 0.4423 0.4346 0.4089 0.3498 0.3192 0.203

1977 0.8334 0.8223 0.7742 0.7217 0.6613 0.3086

1978 0.647 0.6354 0.5897 0.5441 0.5262 0.3175

1979 1.503 1.485 1.431 1.281 1.162 0.5368

1980 1.126 1.105 1.029 0. 9117 0.8497 0.4696

1981 1.078 1.059 0.9976 0.9499 0.8832 0.4903

1982 1.284 1.26 1.167 1.068 0.985 0.4951

1983 1.065 1.047 0.9824 0.8372 0.7499 0.422

1984 0.9807 0.9633 0.902 0.7721 0.6995 0.3738

1985 0.9511 0.9355 0.8812 0.7616 0.6917 0.3574

1986 0.7335 0. 7202 0.6863 0.6483 0.6053 0.3399

1987 0.4155 0.4081 0.3789 0.3583 0.3416 0.2187

1988 1.114 1.094 1.035 0.8973 0.8095 0.3577

1989 0.9367 0.9224 0.8775 0.7989 0.7315 0.3933

1990 0.8894 0.8735 0.8478 0.7831 0.7193 0.3821

Sorted results

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

0.032258064516129 1.503 1.485 1.431 1.281 1.162 0.5368

0.0645161290322581 1.458 1.438 1.379 1.209 1.108 0.4951

### 28

0.0967741935483871 1.438 1.412 1.31 1.135 1.023 0.4903

0.129032258064516 1.309 1.289 1.23 1.068 0.985 0.4836

0.16129032258 0645 1.284 1.26 1.167 1.058 0.9528 0.4696

0.193548387096774 1.237 1.213 1.122 0.9663 0.8832 0.4678

0.225806451612903 1.126 1.105 1.035 0.9499 0.8695 0.4585

0.258064516129032 1.114 1.094 1.029 0.9117 0.8497 0.422

0.290322580645161 1.078 1.059 0.9976 0.8973 0.8095 0.4126

0.32258064516129 1.065 1.047 0.9824 0.8372 0.7499 0.3933

0.354838709677419 0.9807 0.9633 0.902 0.7989 0.7315 0.3821

0.387096774193548 0.9511 0.9355 0.8812 0.7831 0.7193 0.3738

0.419354838709677 0.9367 0.9224 0.8775 0.7721 0.6995 0.3708

0.4516 12903225806 0.8894 0.8735 0.8478 0.7616 0.6917 0.3577

0.483870967741936 0.8334 0.8223 0.7742 0.7217 0.6613 0.3574

0.516129032258065 0.8062 0.7913 0.7434 0.6545 0.6053 0.3442

0.548387096774194 0.7963 0.7825 0.7287 0.6492 0.5975 0.3399

0.580645161290323 0.73 35 0.7202 0.6863 0.6483 0.5957 0.3354

0.612903225806452 0.7308 0.7183 0.6667 0.6063 0.5644 0.3309

0.645161290322581 0.6968 0.6843 0.6359 0.5885 0.5571 0.3175

0.67741935483871 0.6804 0.6684 0.623 0.574 0.5437 0.3086

0.709677419354839 0.647 0.6354 0.5897 0.5 441 0.5262 0.3026

0.741935483870968 0.6005 0.5907 0.5732 0.5221 0.4771 0.24

0.774193548387097 0.5527 0.5429 0.5186 0.4777 0.4427 0.2313

0.806451612903226 0.5312 0.5249 0.4925 0.4303 0.398 0.2288

0.838709677419355 0.5235 0.5142 0.4827 0.4225 0.3943 0.2282

0 .870967741935484 0.4563 0.4483 0.4185 0.3671 0.3416 0.2281

0.903225806451613 0.4423 0.4346 0.4089 0.3583 0.3353 0.2187

0.935483870967742 0.4155 0.4081 0.3789 0.3498 0.3192 0.2177

0.967741935483871 0.4106 0.4039 0.3788 0.3361 0.312 0.203

0.1 1.4251 1.3997 1.302 1.1283 1.0192 0.48963 Average of yearly averages: 0.351543333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run: Output File: RimsTTR_KSsorg_Rsvr2

- aer0625

Metfile: w13996.dvf

PRZM scenario: KSsorghumSTD.txt

EXAMS environ ment file: ir298.exv

Chemical Name: Rimsulfuron TTR Description Variable Name Value Units Comments Molecular weight mwt 324.36 g/mol Henry's Law Const. henry atm

- m^3/mol Vapor Pressure vapr 1.1e

- 8 torr Solubility sol 134 mg/L

Kd Kd mg/L

Koc Koc 207 mg/L Photolysis half

- life kdp 0 days Half

- life Aerobic Aquatic Metabolism kbacw 517 days Halfife Anaerobic Aquatic Metabolism kbacs 178 days Halfife

Aerobic Soil Metabolism asm 3775 days Halfife Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM m anual Incorporation Depth: DEPI 0 cm

### 29

Application Rate: TAPP 0.035 kg/ha Application Efficiency: APPEFF 0.95 fraction Spray Drift DRFT 0.16 fraction of application rate applied to pond Application Date Date 25

- 06 dd/mm or dd/mmm or dd

- mm or dd

- mmm Record 17 : FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5 Flag for Index Res. Run IR Reservoir Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)



## PRZM/EXAMS (PE5 Shell) Modeling File (Parent Rimsulfuron)

stored as Rimsu_KSsorg_Eco6

- aer0605.out

Chemical: Rimsulfuron PRZM environment: KSsorghumSTD.txt modified Tueday, 29 May 2007 at 12:55:46 EXAMS environment: pond298.exv modified Thuday, 24 July 2003 at 09:02:00

Metfile: w13996.dvf modified Wedday, 3 July 2002 at 08 :04:44 Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.2226 0.1845 0.1015 0.04942 0.03339 0.008238

1962 0.115 0.09534 0.06457 0.03327 0.02236 0.005516

1963 0.1108 0.09184 0.06232 0.03066 0.02073 0.005116

1964 0.3219 0 .2669 0.1749 0.07267 0.04861 0.01196

1965 0.2049 0.1732 0.1116 0.04616 0.03088 0.007615

1966 0.3238 0.2685 0.1876 0.07917 0.05297 0.01306

1967 0.2419 0.2101 0.1371 0.05755 0.03851 0.009496

1968 0.2891 0.2397 0.1422 0.06391 0.04297 0.01057

1969 0.5924 0.491 1 0.2682 0.1149 0.07698 0.01899

1970 0.4506 0.374 0.1929 0.08392 0.05628 0.01388

1971 0.2077 0.1722 0.09681 0.04194 0.02809 0.006928

1972 0.111 0.09205 0.06247 0.03329 0.02258 0.005558

1973 0.1407 0.1173 0.06572 0.04104 0.02853 0.007052

1974 0.3092 0.2566 0.1466 0.06073 0.04066 0.01003

1975 0.4195 0.3645 0.1954 0.08218 0.055 0.01356

1976 0.08749 0.07253 0.04245 0.02458 0.01677 0.004131

1977 0.4187 0.3471 0.2168 0.09605 0.06441 0.01589

1978 0.5381 0.4641 0.2411 0.1071 0.07217 0.01781

1979 0.2137 0.1774 0.098 03 0.04283 0.02868 0.007074

1980 0.08749 0.07253 0.0373 0.01496 0.01635 0.004126

1981 0.4649 0.3854 0.2055 0.08959 0.06002 0.0148

1982 0.1646 0.1365 0.08643 0.03621 0.02423 0.005975

1983 0.1293 0.1072 0.07018 0.03258 0.02184 0.005386

1984 0.09302 0.08141 0 .05318 0.02353 0.01576 0.003876

1985 0.08749 0.07253 0.05026 0.02701 0.01828 0.004512

1986 0.1366 0.1133 0.06589 0.03902 0.02633 0.006496

1987 0.3095 0.2566 0.1445 0.06649 0.04457 0.01099

1988 0.3632 0.3154 0.165 0.07806 0.05337 0.01314

1989 0.1145 0.09902 0.05623 0.03466 0.02335 0.005762

1990 0.089 0.07575 0.05983 0.0262 0.01755 0.004329

Sorted results

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

0.032258064516129 0.5924 0.4911 0.2682 0.1149 0.07698 0.01899

### 30

0.0645161290322581 0.5381 0.4641 0.2411 0.1071 0 .07217 0.01781

0.0967741935483871 0.4649 0.3854 0.2168 0.09605 0.06441 0.01589

0.129032258064516 0.4506 0.374 0.2055 0.08959 0.06002 0.0148

0.161290322580645 0.4195 0.3645 0.1954 0.08392 0.05628 0.01388

0.193548387096774 0.4187 0.3471 0.1929 0.08218 0.055 0.01356

0.225806451612903 0.3632 0.3154 0.1876 0.07917 0.05337 0.01314

0.258064516129032 0.3238 0.2685 0.1749 0.07806 0.05297 0.01306

0.290322580645161 0.3219 0.2669 0.165 0.07267 0.04861 0.01196

0.32258064516129 0.3095 0.2566 0.1466 0.06649 0.04457 0.0109 9

0.354838709677419 0.3092 0.2566 0.1445 0.06391 0.04297 0.01057

0.387096774193548 0.2891 0.2397 0.1422 0.06073 0.04066 0.01003

0.419354838709677 0.2419 0.2101 0.1371 0.05755 0.03851 0.009496

0.451612903225806 0.2226 0.1845 0.1116 0.04942 0.03339 0.008238

0.483870967741936 0.2137 0.1774 0.1015 0.04616 0.03088 0.007615

0.516129032258065 0.2077 0.1732 0.09803 0.04283 0.02868 0.007074

0.548387096774194 0.2049 0.1722 0.09681 0.04194 0.02853 0.007052

0.580645161290323 0.1646 0.1365 0.08643 0.04104 0.02809 0.0069 28

0.612903225806452 0.1407 0.1173 0.07018 0.03902 0.02633 0.006496

0.645161290322581 0.1366 0.1133 0.06589 0.03621 0.02423 0.005975

0.67741935483871 0.1293 0.1072 0.06572 0.03466 0.02335 0.005762

0.709677419354839 0.115 0.09902 0.06457 0.03329 0.02258

0.0 05558

0.741935483870968 0.1145 0.09534 0.06247 0.03327 0.02236

0.005516

0.774193548387097 0.111 0.09205 0.06232 0.03258 0.02184

0.005386

0.806451612903226 0.1108 0.09184 0.05983 0.03066 0.02073

0.005116

0.838709677419355 0.09302 0.08141 0.05623 0.02701 0.0 1828

0.004512

0.870967741935484 0.089 0.07575 0.05318 0.0262 0.01755 0.004329

0.903225806451613 0.08749 0.07253 0.05026 0.02458 0.01677

0.004131

0.935483870967742 0.08749 0.07253 0.04245 0.02353 0.01635

0.004126

0.967741935483871 0.08749 0.07253 0.0373 0.0 1496 0.01576

0.003876

0.1 0.46347 0.38426 0.21567 0.095404 0.063971 0.015781
Average of yearly averages: 0.0090622

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run: Output File: Rimsu_KSsorg_Eco6

- aer0605

Metfile: w13996.dvf

PRZM s cenario: KSsorghumSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Rimsulfuron Description Variable Name Value Units Comments Molecular weight mwt 431.44 g/mol
Henry's Law Const. henry atm

- m^3/mol

Vapor Pressure vapr 1.1e

- 8 torr Solubility sol 7 300 mg/L

Kd Kd mg/L

Koc Koc 47.5 mg/L
Photolysis half

- life kdp 0 days Half

- life Aerobic Aquatic Metabolism kbacw 0 days Halfife Anaerobic Aquatic Metabolism kbacs 4.2 days Halfife

Aerobic Soil Metabolism asm 44.8 days Halfife Hydrolysis: pH 7 7.2 days Hal f

- life

### 31

Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 0.035 kg/ha
Application Efficiency: APPEFF 0.95 fraction Spray Drift DRFT 0.05 fraction of application rate applied to pond Application Date Date 05

- 06 dd/mm or dd/mmm or dd

- mm or dd

- mmm
Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5
Flag for Index Res. Run IR EPA Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 32



## Appendix B

– Ground Water Mod eling Supporting

Documentation

PRZM

- GW Modeling Input and Output File s

PRZM

- GW estimated upper bound concentrations in ground water (ppb) for rimsulfuron and degradates of concern including IN

- 70941 and IN

- 70942.

Crops (scenario) Highest Daily Value (Acute) Post

- Breakthrough Average (Chronic and Cancer)

ALS inhibition tolerant sorghum (FL citrus) 7.33 6 .0

Sorghum (WI corn) 12.4 11.3

All uses (WI corn) 22.2 20.1

Sorghum (DE corn) 7.29 5.97

Sorghum (NC cotton) 8.63 6.96

(GA peanut) 3.49 3.1 5 (FL potato) 4.19 3.65 Highest acute and chronic DWECs for sorghum new use and all existing uses are

bolded

.



## PRZM

- GW Shell Processing File (WI Corn Scenario, 0.0625 lb ai/A Rate)

Rimsulfuron TTR

0

1526

True

262

1

1
25,,,,,,,,,,

### 33

06,,,,,,,,,,
0.07,,,,

,,,,,, 1,,,,,,,,,,

,,,,,,,,,, True

1

last

Wisconsin Corn

- WI Central Sands

C: \ Models \ Inputs \ Metfiles \ w14920.dvf

0.76

0.36

18

90

100

0.25

01

05

21

07

20

10

1

2

0.1

0

4.0

9
1.63,1.63,1.68,1.68,1.59,1.59,1.59,1.59
0.088,0.088,0.079,0.079,0.068,0.068 ,0.068
0.034,0.034,0.025,0.025,0.016,0.016,0.016
0.46,0.46,0.14,0.09,0.09,0.08,0.07,0.07

True 95,95,96,96,97,97,97,97
2.3,2.3,2.5,2.5,1.7,1.7,1.7,1.7

5.6

0.2

50

1

### 34



## PRZM

- GW Input File (WI Corn Scenario, 0.0625 lb ai/A Rate)

3/3/2014 7:09:17 PM; Rimsulfuro n TTR; Wisconsin Corn

- WI Central Sands

User Interface Version: PRZM

- GW (Version 1.01)

***Record 3

0.76 0.36 0 18 1 1

***Record 6

0

***Record 8

1

***Record 9

1 0.25 90 100 1 10 10 10 0 100

***Record 10

30

***Record 11

010561 210761 201061 1

010562 210762 201062 1

010563 210763 201063 1

010564 210764 201064 1

010565 210765 201065 1

010566 210766 201066 1

0105 67 210767 201067 1

010568 210768 201068 1

010569 210769 201069 1

010570 210770 201070 1

010571 210771 201071 1

010572 210772 201072 1

010573 210773 201073 1

010574 210774 201074 1

010575 210775 201075 1

010576 210776 201076 1

010577 210777 201077 1

010578 210778 201078 1

010579 210779 201079 1

010580 210780 201080 1

010581 210781 201081 1

010582 210782 20108 2 1

010583 210783 201083 1

010584 210784 201084 1

010585 210785 201085 1

010586 210786 201086 1

010587 210787 201087 1

010588 210788 201088 1

010589 210789 201089 1

010590 21079 0 201090 1

***Record 12

Place Holder

***Record 13

30 1 0 0

### 35

***Record 15

Place Holder

***Record 16

25 661 0 1 4 0.07 1 0

25 662 0 1 4 0.07 1 0

25 663 0 1 4 0.07 1 0

25 664 0 1 4 0. 07 1 0

25 665 0 1 4 0.07 1 0

25 666 0 1 4 0.07 1 0

25 667 0 1 4 0.07 1 0

25 668 0 1 4 0.07 1 0

25 669 0 1 4 0.07 1 0

25 670 0 1 4 0.07 1 0

25 671 0 1 4 0.07 1 0

25 672 0 1 4 0.07 1 0

25 673 0 1 4 0.07 1 0

25 674 0 1 4 0.07 1 0

25 675 0 1 4 0.07 1 0

25 676 0 1 4 0.07 1 0

25 677 0 1 4 0.07 1 0

25 678 0 1 4 0.07 1 0

25 679 0 1 4 0.07 1 0

25 680 0 1 4 0.07 1 0

25 681 0 1 4 0.07 1 0

25 682 0 1 4 0.07 1 0

25 683 0 1 4 0.07 1 0

25 684 0 1 4 0.07 1 0

25 685 0 1 4 0.07 1 0

25 686 0 1 4 0.07 1 0

25 687 0 1 4 0.07 1 0

25 688 0 1 4 0.07 1 0

25 689 0 1 4 0.07 1 0

25 690 0 1 4 0.07 1 0

***Record 17

0 1 0

***Record 19

Place Holder

***Record 20

1000 0 0 0 0 0 2 1 1 0

***Record 26

0 0 0

***Record 27

3 0.1 0 4.0

***Record 31

0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.97 10.0

***Record 32

5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6 5.6

***Record 32A

2.00 25.0

### 36

***Record 33

8
*** Record 34,36,37 Horizon 1

1 10 1.63 0.088 0 0 0

0.0004540.000454 0

1 0.088 0.034 0.46 1.2052

5.6 95 2.3 0 0
*** Record 34,36,37 Horizon 2

2 10 1.63 0.088 0 0 0

0.0004290.000429 0

5 0.088 0.034 0.46 1.2052

5.6 95 2.3 0 0

*** Reco rd 34,36,37 Horizon 3

3 20 1.68 0.079 0 0 0

0.0003530.000353 0

20 0.079 0.025 0.14 0.3668

5.6 96 2.5 0 0
*** Record 34,36,37 Horizon 4

4 20 1.68 0.079 0 0 0

0.0002520.000252 0

20 0.079 0.025 0.09 0.2358

5.6 96 2.5 0 0
*** Record 34,36,37 Horizon 5

5 20 1.59 0.068 0 0 0

0.0001510.000151 0

20 0.068 0.016 0.09 0.2358

5.6 97 1.7 0 0
*** Record 34,36,37 Horizon 6

6 20 1.59 0.068 0 0 0

5.05E

- 055.05E

- 05 0

20 0.068 0.016 0.08 0.2096

5.6 97 1.7 0 0
*** Record 34,36,37 Horizon 7

7 800 1.59 0.068 0 0 0

0 0 0

50 0.068 0.016 0.07 0.1834

5.6 97 1.7 0 0
*** Record 34,36,37 Horizon 8

8 100 1.59 0.396 0 0 0

0 0 0

50 0.396 0.001 0.07 0.1834

5.6 97 1.7 0 0

*** Record 40

0

*** Record 42

YEAR 10 YEAR 10 YEAR 10

0

*** Record 45

3 YEAR

### 37

*** Record 46

DCON1 TAVE 33 34 1.0E3

INFL TCUM 33 33 0.00277

IRRG TSER

### 38

Figure 2

. PRZM

- GW rimsulfuron residues of concern concentration time series chemographs (30

- year simulation).

FL citrus

– sorghum use

WI corn

– sorghum use

### 39

DE Corn

### 40

WI Corn (highest rate for all use sites)