Document ID: EPA-HQ-OPP-2009-0004-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-12-18T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES



  SEQ CHAPTER \h \r 1 							PC Code 	129009

			DP Barcode	D358869, D358875

Date                   July 24, 2009 

MEMORANDUM

™ OPTIMUM® GAT® Corn and Soybeans

TO:			Vickie Walters, Risk Manager Reviewer

			James Tompkins, Product Manager 25

			Daniel Kenny, Chief

			Herbicide Branch

			Registration Division (7505P)

AND:			Douglas Dotson

Cristina Swartz, Chief

			Registration Action Branch II

			Health Effects Division (7509P)

FROM:		José L. Meléndez, Chemist

			Environmental Risk Branch V

			Environmental Fate and Effects Division (7507P)  

APPROVED BY:	Mah T. Shamim, Branch Chief

			Environmental Risk Branch V

			Environmental Fate and Effects Division (7507P)

		

This memorandum presents the Tier 1 Estimated Drinking Waters
Concentrations (EDWCs) for surface and ground waters for rimsulfuron, a
pyrimidinyl sulfonylurea herbicide (CAS name:
N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyr
idinesulfonamide; CAS No. 122931-48-0), calculated using the Tier 1
aquatic models FIRST and SCI-GROW, for use in the human health risk
assessment.  This Drinking Waters Assessment (DWA) is largely based on a
previous DWA, dated February 6, 2007 (electronic copy is provided in
Appendix B).  The EDWCs were calculated based on the maximum application
rate of 0.0625 lb a.i./A/season (for citrus, pome and stone fruits,
ground broadcast application, wetted in).  For rimsulfuron, the surface
waters acute value is 5.596 ppb, and the cancer/ chronic value is 0.120
ppb.  The groundwater screening concentration is 0.016 ppb of
rimsulfuron, which is suitable for acute and chronic (refer to Table 1).
 EFED stresses the fact that this is a Tier 1 screening-level analysis
and should there be the need, additional levels of refinements are
possible.

Currently, rimsulfuron is used on a number of crops, including corn
(maximum application rate for corn, 0.03125 lb a.i./A).  EFED evaluated
the new uses for rimsulfuron on DUPONT™ OPTIMUM® GAT® herbicide
tolerant corn and soybean for pre-emergence and post-emergence control
of certain annual grass and broadleaf weeds.  The product name is
RESOLVE™ SG Herbicide (water soluble granule, containing 25% a.i.). 
It was noted that aerial applications are allowed for these uses and the
maximum application rate is 0.0625 lb a.i./A for both crops (same than
the previously assessed for citrus, pome and stone fruits).  It was
evaluated if the new scenarios posed more exposure than previously
assessed.  The results of a FIRST run showed lower EDWCs than the
previously assessed scenarios (refer to Appendix A for the table of
input parameters used, and a copy of the output file from FIRST). 
Therefore, EFED relied on the results of the previous DWA for this
assessment.  It appears that, because the pesticide is not wetted in and
a specific PCA was used (for corn and soybeans, 0.83), the results were
lower for the new scenarios.

None of rimsulfuron’s transformation products were included in this
assessment.  Based on a HED’s March 29, 1994 memorandum, it was
concluded that, “None of rimsulfuron’s metabolites warrant inclusion
in tolerance regulation or separate regulation or inclusion in the
dietary risk assessment” (refer to Attachment 1 of Appendix B). 
Rimsulfuron shows significant levels of various transformation products
that may persist in the environment and may contaminate surface or
ground waters.

For information related to the environmental fate characteristics of
rimsulfuron, mode of action, uncertainties, etc., please, refer to the
previous DWA, provided in Appendix B.  For any questions related to this
document, please, contact us in EFED.

Table 1. Maximum Tier I EDWCs for drinking water assessment based on
ground application of rimsulfuron*

Use/Rate Modeled:      Fruit trees applied once, by ground sprayers, at
a rate of 0.0625 lbs. a.i./A

Chemical	Maximum Surface water EDWC (ppb)	Maximum Ground water

Acute/Chronic EDWC (ppb)

	Acute Value	Chronic/Cancer Value

	Rimsulfuron Parent	5.596	0.120	0.016

* Degradates are not included as recommended by HED Metabolism
Committee.  Please, refer to Appendix B for further details.

Appendix A.  FIRST Supplementary Run Inputs Parameter Table and Output
File 

Table A1.  FIRST input parameters for modeling drinking water EDWCs

Input Parameter	Value*	Reference

Application Rate (lb a.i./Acre)	0.0625 (One Application)	Maximum label
rate/Minimum application intervals (Product Label)

Application Intervals (days)	Does not apply, 1 applic.

	Percent Crop Area	0.83	Corn and soybeans

Partition Coefficient “KOC” (L/Kg)	19	Lowest non-sand value (MRID
413563-36) 

Aerobic Soil Metabolism Half-life (days)	64	Determined by multiplying
the available half-life by 3 to account for the uncertainty associated
with using a single value  (21.3x3; MRID 413563-34)

Wetted In?	No	Product Label

Depth of Incorporation (inches)	0

	Method of Application	Aerial

	Solubility in Water (ppm)	7.3	MRIDs: 419316-02 and 413563-01.

Aerobic Aquatic Metabolism Half-life (days)	The experiment was exposed
to artificial light source thus the value was not used and hydrolysis
half-live was entered.

Hydrolysis Half-life @ pH 7 (days)	7.2	Average value at pH 7 (MRID
413563-33) 

Direct Aqueous Photolysis Half-life(days)	Stable	Half-lives in
dark<irradiated 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.

Appendix A.  FIRST Supplementary Run Inputs Parameter Table and Output
File (cont.)

FIRST Output Run:

   RUN No.   1 FOR Rimsulfuron      ON   Soy+Corn      * INPUT VALUES * 

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

    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP

     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)

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

  0.063(  0.062)   1   1      19.0    7.3   AERIAL(16.0)  83.0   0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 

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

     64.00        2           0.00    0.00-    0.00    7.20       7.20

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1  MAR 26, 2008

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              5.138                      0.111

Appendix B.  Electronic Copy of Previous Drinking Waters Analysis

  SEQ CHAPTER \h \r 1 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

                                                              OFFICE OF

                                                                        
      PREVENTION, PESTICIDES

                                                                        
       AND TOXIC SUBSTANCES

							

			

PC Code No.:		129009

						DP Barcode: 		D 334221

Date:			February 6, 2007	

MEMORANDUM

SUBJECT:	Estimated Drinking Water Concentrations of Parent Rimsulfuron
for the Use in Human Health Risk Assessment.

TO:		James Tompkins, Risk Manager 25

		Vickie Walters, Risk Manager Reviewer

		John Redden, Team Leader, ARIA

		Registration Division (7505P)

AND:		Christina Swartz, Branch Chief

RAB2, HED (7509P)

FROM:	M. A. Ruhman, Agronomist, Environmental Fate Reviewer

		Environmental Fate and Effects Division (7507P)

THROUGH:	Mah T. Shamim, Ph.D., Chief

Environmental Risk Branch V

		Environmental Fate and Effects Division (7507P)

I. EXECUTIVE SUMMARY

This memo presents the Estimated Drinking Water Concentrations (EDWCs)
for parent Rimsulfuron for use in an FQPA human health risk assessment. 
It is noted that significant quantities of some of rimsulfuron
transformation products/degradates may persist in the environment and
may contaminate surface/ground water.  None of these transformation
products/degradates are included in this risk assessment based on HED
Metabolism Committee Memorandum dated March 29, 1994. The Committee
concluded that “None of the rimsulfuron metabolites warrant inclusion
in the tolerance regulation or separate regulation or inclusion in the
dietary risk assessment” (Attachment No. 1). 

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

Rimsulfuron is selective/systemic pyrimidinyl sulfonylurea herbicide. 
Rimsulfuron is a member of the sulfonylurea family  with a mode of
action that inhibit acetolactate synthase ALS (ALS is also known as
acetohydroxyacid synthase AHAS) (HRAC Group B). ALS or AHAS is a key
enzyme in biosynthesis of certain amino acids in plants.  This herbicide
is currently registered as pre/post emergence weeds control in field
corn, potatoes, potatoes grown for seed, and field grown tomatoes.  The
registrant is seeking new section 3 registration for new use on grapes,
stone Fruit, tree nuts, pistachios, pome fruit, and citrus fruit. These
proposed new uses for rimsulfuron may cause the chemical to reach
surface and to a lesser extent groundwater under some conditions.  

The screening level surface water and ground water estimates for
rimsulfuron parent are calculated using tier 1 models of FIRST (version
1.0) and SCI-GROW (version 2.3), respectively.   The estimates are
presented in Table 1 for surface/ground water.

Table 1. Maximum Tier I EDWCs for drinking water assessment based on
ground application of rimsulfuron*

Full chemical name: 
N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyr
idine sulfonamide

CAS No.:                     122931-48-0

PC Code:                     129009

Use/Rate Modeled:      Fruit trees applied once, by ground sprayers, at
a rate of 0.0625 lbs. a.i./A

Chemical	Maximum Surface water EDWC (ppb)	Maximum Ground water

Acute/Chronic EDWC (ppb)

	Acute Value	Chronic/Cancer Value

	Rimsulfuron Parent	5.596	0.120	0.016

* Degradates are not included as recommended by HED Metabolism
Committee.

The above stated values for parent rimsulfuron represent upper-bound
estimates of concentrations that might be found in surface water and
groundwater due to the propose new use of the chemical on grapes, stone
Fruit, tree nuts, pistachios, pome fruit, and citrus fruit using one
application at the maximum yearly rate (worst case scenario).  EFED
emphasizes that this is a tier 1 screening-level analysis, and should
there be a need, by HED, additional refinements can be made. It is noted
that this assessment supersedes earlier assessment entitled
“Preliminary Drinking Water Exposure Assessment” Dated 02/25, 1998.
In this referenced assessment older models and parameter guidance were
used. 

Only one aerobic soil study was submitted and in order to be protective
it was necessary to multiply this half-life by 3 before use in modeling.
 The geographic extent of use warrant the submission of new aerobic soil
studies using soils representing new/current use areas.  Uncertainties
in representation of the default half-life may result in conservative
EDWCs.

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

II. PROBLEM FORMULATION

This is a Tier I drinking water assessment that uses modeling (no
monitoring data is available) to estimate the surface and ground water
concentrations of pesticides in drinking water source water
(pre-treatment) resulting from pesticide use on sites that are highly
vulnerable.  This initial tier screens out chemicals with low potential
risk and provides estimated exposure concentrations for human health
dietary risk assessment.

 

III. ANALYSIS

(1) Use Characterization

Rimsulfuron herbicide formulation (DPX-E9636 FNV Dry Flowable) contains
25.0% of the active ingredient is proposed to be applied, by injection
through sprinkler irrigation or by ground equipment only. For ground
application, the herbicide is applied as a uniform broadcast to orchard
or vineyard floor or as a uniform band at the base of the trunk or vine.
 The best results can be obtained from this systematic pre/early post
emergence herbicide by applying to cool soils and by moisture activation
within 2-3 weeks of application. Activation can be achieved by rainfall
or overhead irrigation of a minimum of ½ to 1 inch.  The herbicide is
recommended for use on vigor and healthy trees that have been
established for two full growing seasons.  One single application of 4
ounces of product in 10 gallons of <4 or >8 pH buffered water/acre/year
is recommended for either the broadcast or the band treatments.  The
chemical may be applied twice (maximum 4 ounces) on 50% or less band
along the base of the trees with a minimum of 30-day intervals. It is
claimed to control susceptible weeds over a period of 60 to 90 days.

The maximum label rates for the proposed new uses are presented in Table
2.

Table 2. Rimsulfuron use patterns (Maximum rates/number and minimum
intervals are included).

Crop	Spray Type	Target	Application: Maximum Rate/Number and Minimum
Interval

	Rate (lb a.i./Acre)	Number	Interval (days)

Citrus/Pome/Stone Fruits, Tree nuts, and Grapes

	Ground

Broadcast injection through sprinkler	

Whole Soil Surface	0.0625	1	Not applicable

	Ground

Broadcast Banded 

	A soil surface band through base of trees

	0.0625	1

0.03125 *	2	30

* Assuming that each application= half of the yearly application 

(2) Environmental Fate/Transport Characterization

Table 1 (Attachment No. 2) contains a detailed summary of the
physical/chemical and environmental fate/transport properties of
rimsulfuron. Hereunder, is a summary of various parameters that relates
to its predicted behavior in various compartments of the 

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

environment and possible contamination of surface/ground water.

(a) Environmental Persistence/Mobility

Rimsulfuron has a low vapor pressure (1.447 x10-11 atms. at 25 oC) and
is highly soluble in water (solubility 7.3 ppm at 20 oC).  Based on
submitted environmental fate studies, the chemical is short lived in
aqueous systems (mainly affected by hydrolysis with hydrolysis
half-lives ranging from 5-7 days in acidic/neutral conditions and <1day
in alkaline conditions). Also the chemical is short-lived in
aerobic/anaerobic soil systems (t1/2= 19-21 days determined for only one
soil, shorter half-lives were determined under field conditions: t1/2= 5
to 18 days).  Rimsulfuron appears not to be affected by aqueous/on soil
photolysis. 

Adsorption/desorption were studied using four soils with varied texture
and organic matter contents (clay content= 4-30% and organic carbon
content= 0.6-2.5%). The observed partitioning coefficient Koc ranged
from 19-74 L Kg-1 suggesting that rimsulfuron may be highly mobile and
vulnerable to run-off and leaching.  Therefore, the chemical may reach
surface and ground water resources. 

(b) Environmental Metabolites and their Persistence/Mobility

Rimsulfuron is expected to transform/degrade into a number of
transformation/ degradation products under different environmental
conditions (Figure 1, Attachment No. 3).  The three major degradates for
rimsulfuron result from contraction or cleavage or the sulfonurea-bridge
(IN-70941 and IN-70942 from contraction while IN-J9260 from cleavage). 
In contrast, the minor degradates are cleavage degradates (IN-J9260 in
systems other than aerobic soil, IN-J290 and IN-T5831). A summary of the
degradation profiles in various laboratory systems is included in Table
3.

Table 3. Transformation/degradation profiles of rimsulfuron in various
systems.

Degradate

Name 	Max Degradate Concentration in % of applied  and (Time in Days to
Max Concentration; Does it Decline Y/N)

	Hydrolysis @ pH7	Aerobic Soil	Anaerobic Soil	Other Studies

IN-70941	17%

(3 days; Y to 1%)	55%

(10 days; Y to 30%)	32%

(10 days; Y to 6%)	H2OPhotolysis: Similar to hydrolysis with reduction
in transformation of IN-70941 into IN-70942 and/or increase in the
degradation of IN-70942. Plus enhanced formation of IN-J920 and IN-E9260

Aerobic Aquatic Data: May not represent the natural environment as the
system was exposed to light

TFD (Terrestrial Field Dissipation) Data: None Identified possibly due
to inappropriate LOD/LOQ (limits of detection/quantification)

IN-70942	84%

(30 days; N)	30%

(360 days; N)	56%

(360 days; N)

	IN-E9290	10%

(30 days; N)	19%

(30 days; Y to 16%)	23%

(360 days; N)

	IN-J290	7%

(14 days; Y to 6%)	3%

(30 days; Y to 1%)	8%

(28 days; Y to 6%)

	App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

Degradate

Name 	Max Degradate Concentration in % of applied  and (Time in Days to
Max Concentration; Does it Decline Y/N)

	Hydrolysis @ pH7	Aerobic Soil	Anaerobic Soil	Other Studies

IN-T5831	None

Only Minor @ pH 5	1%

(270 days, Y to <1%)	1%

(360 days, N)

	

Mobility of the transformation products/degradates were checked by TLC
(thin layer chromatography) and results indicate high mobility to
IN-E9260 and high to medium mobility for IN-70941, IN-70942 and IN-J290.
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. Considering quantities formed
and relative persistent, the three rimsulfuron degradates are expected
to reach both surface and ground water at varied concentrations.  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. Finally, IN-70942
is expected to be the terminal and persistent degradate. 

(3) Drinking Water Exposure Modeling

(a) Models

Surface and ground water EECs for drinking water (EDWCs) for rimsulfuron
were obtained by modeling using tier 1 FIRST (version 1.0) and SCIGROW
(version 2.3) simulated models, respectively.  

FIRST (FQPA Index Reservoir Screening Tool) is a meta-model of PRZM and
EXAMS used as a screening tool to estimate pesticide concentrations
found in surface water used as drinking water. FIRST was developed by
making multiple runs of PRZM using varying sorption coefficients and
determining the concentration in the EXAMS index reservoir scenario
after a two-inch single storm event. (The Index Reservoir is a standard
water body used by the Office of Pesticide Programs to assess drinking
water exposure (Office of Pesticide Programs, 2002). It is based on a
real reservoir (albeit not currently in active use as a drinking water
supply), Shipman City Lake in Illinois, that is known to be vulnerable
to pesticide contamination.) The single runoff event moves a maximum of
8% of the applied pesticide into the reservoir (FIRST Users Manual;
08/01/2001).

SCIGROW (Screening Concentration in Ground Water) is a regression model
used as a screening tool to estimate pesticide concentrations found in
ground water used as drinking water. SCIGROW was developed by fitting a
linear model to groundwater concentrations with the Relative Index of
Leaching Potential (RILP) as the independent variable. Groundwater
concentrations were taken from 90-day average high concentrations from
Prospective Ground Water studies; the RILP is a function of aerobic soil
metabolism and the soil-water partition coefficient. The output of
SCIGROW represents the concentrations that might be expected in shallow
unconfined aquifers under sandy soils, which is representative of the
ground water most vulnerable to pesticide contamination likely to serve
as a drinking water source ( SCIGROW: Users 

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

Manual (11/01/2001, revised 08/23/2002).

If drinking water levels of concern are exceeded for Tier I surface
water EDWCs, Tier II modeling will be able to refine these EDWCs by
including volatility, Henry’s Law, diffusion in air, and enthalpy
considerations. Since SCIGROW is a regression model developed from
actual pesticide data with a range of volatilities, systematic
conclusions cannot be drawn about over or underestimation of groundwater
EDWCs at Tier I.

(b) Modeling Approach and Input Parameters

Input values used in FIRST modeling were based on the label and
fate/transport parameters and are summarized in Table 4.

Table 4. FIRST input parameters for modeling drinking water EDWCs.

Input Parameter	Value*	Reference

Application Rate (lb a.i./Acre)	0.0625 (One Application)

0.0313 (Two Application)	Maximum label rate/Minimum application
intervals (Product Label)

Application Intervals (days)	30

	Percent Crop Area	0.87	Fruit trees

Partition Coefficient “Koc” (L Kg-1)	19	Lowest non-sand value (MRID
413563-36) 

Aerobic Soil Metabolism Half-life (days)	64	One half-life x 3 (21.3x3;
MRID 413563-34)

Wetted In?	Yes	Product Label

Depth of Incorporation (inches)	0

	Method of Application	Ground**

	Solubility in Water (ppm)	7.3	MRIDs: 419316-02 and 413563-01; Using
water solubility of 7,300 ppm have not affected the results.

Aerobic Aquatic Metabolism Half-life (days)	The experiment was exposed
to artificial light source thus the value was not used and hydrolysis
half-live was entered.

Hydrolysis Half-life @ pH 7 (days)	7.2	Average value at pH 7 (MRID
413563-33) 

Direct Aqueous Photolysis Half-life(days)	Stable	Half-lives in
dark<irradiated 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.

** The label permits application through the Sprinkler Irrigation
Systems (reason for choosing ground application is stated in the text) 

Modeling was simulated for applying the pesticide once or twice as
stated in the label. The results, for two applications, were lower
compared to one application possibly due to degradation within the
30-day interval between applications (Table 5).  For reference, sample
runs are included in Attachment No. 4.

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

Table 5. Modeled EDWCs of rimsulfuron in surface water.

Application Procedure/Time Line	Peak Day (Acute; ppb)             
Annual Average (Chronic; ppb)

Once (applied only one time)	5.596	0.120

Twice (divided in half with 30-day interval)	4.786	0.103

Although higher drift might be associated with sprinkler irrigation,
ground application was chosen for the simulation as the EDWCs were more
conservative.  This was confirmed by running the model with drift value
of up to 16% (aerial application) which gave lower EDWCs (i.e. less
conservative values).  The reason for such results is associated with
the how concentrations are calculated by the model combined by the fact
that this chemical has low affinity to soil particles resulting in
higher importance of run-off than drift. As shown in Table 6, the model
calculates lower amounts of the pesticide pool available for run-off in
aerial compared to ground spray (amount of 2.114 lbs compared to 2.028
lbs). Although, the model calculates higher amount of drift for aerial
compared to ground (0.130 lbs for aerial compared to 0.052 lbs for
ground), these amounts are only 3-6% of the pesticide run-off pool.

 

Table 6. Rimsulfuron: Amount of run-off and drift pools as calculated by
FIRST.

Pesticide Pools	Ground spray	Aerial spray.	Bases for the calculation

Run-off	2.114 lbs

(427 x 0.0625*x 0.08

x 0.99)	2.028 lbs

(427 x 0.0625*x 0.08

x 0.95)	8% of the total mass of pesticide applied to 427 acres watershed
with application efficiency of 99% for ground and 95% for aerial.

Drift	0.052 lbs

(13 x 0.0625* 

x 0.064)	0.130 lbs

(13 x 0.0625* 

x 0.16)	Fraction of the rate of the amount applied to 13 acres water
body with drift values of 6.4% for ground and 16% for aerial.

* The value of 0.0625 = application rate which is equal to 0.0625 lb
a.i./Acre.

Input values used in SCI-GROW modeling were based on the label and
fate/transport parameters summarized in Table7.

Table 7. SCI-GROW input parameters for modeling drinking water from
ground water (EDWCs).

Input Parameter	Value	Reference

Application Rate (lb a.i./Acre)	0.0625	Maximum Yearly Application rate
(Product Label)

Maximum Number of Applications/Year	1

	Partition Coefficient “Koc” (L Kg-1)	55	Median of 4 values (<3 fold
variations in Kocs (MRID 413563-36) 

Aerobic Soil Metabolism Half-life (days)	21.3	One half-life (MRID
413563-34)

A summary of the results is included in Table 8. For reference, a sample
run is included 

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

in Attachment No. 4.

Table 8. Summary of outputs from SCI-GROW for rimsulfuron.

Application Procedure/Time Line	Acute and Chronic Values (ppb)

Once (applied only one time)	0.0158

Twice (divided in half with 30-day interval)	0.0158

IV. MONITORING DATA

Although this pesticide is currently registered for use, no monitoring
data was found or submitted.

V. DRINKING WATER TREATMENT

No data were submitted for drinking water treatment effects. However,
water treatment may include water softening which generally increase the
pH.  This pesticide is expected to hydrolyze at much faster rates in
alkaline systems (half-life of 4-11 hours at pH 9 compared to 5-7 days
at pHs 5 and 7).  Therefore, enhanced degradation is expected as result
of water treatment raising the potential for lower EDWCs in treated
water compared to the modeled raw water.

VI. CONCLUSIONS

For surface water, only one aerobic soil half-life was available, EDWCs
were calculated based on a default half-life value that is three times
longer.  Therefore, EDWCs could therefore be conservative. The
registrant may submit additional aerobic soil studies to represent the
range of texture and organic matter for soils in the expanded use areas.

For ground water: only one aerobic soil half-life was available and
used.  Resultant EDWCs could therefore be underestimated because of the
use of single aerobic soil half-life.

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

ATTACHMENT No. 1: 

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

ATTACHMENT No. 2: 

Table 1.  The physical/chemical and environmental fate/transport
properties of rimsulfuron: a detailed summary.

Parameter	Value	Source

I. Physical/chemical properties

Classification	Pyrimidinyl Sulfonylurea	Registrant Data and the Web 1

Molecular Formula	C14H17N5O7S2

	PC Code	129009

	Chemical Name (IUPAC)
1-(4,6-dimethoxypyrimidin-2-yl)-3-(3-ethylsulfonyl-2-pyridylsulfonyl)ure
a

	Chemical Name (CAS)
N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(ethylsulfonyl)-2-pyr
idine sulfonamide

	CAS Number	122931-48-0	MRIDs:

419316-02

413563-01

Molecular Weight	431.44

	pKa	4

	H20 Solubility (ppm)	7.3 @ pH 7/25 oC 2

	Vapor pressure (25oC)	1.1x10-8 torr Equal to 1.447x10-11 atms.

	Henry's Law Constant	1.40x10-12 atms. m 3 . mole -1 (Calculated)

	Octanol/Water Partition, Kow	1 @ pH7 and 87 @ pH 5 (log KOW 0.034 @ pH7
&1.94 @ pH 5)

	II. environmental fate/transport properties

Hydrolysis	t½= 4.5- 4.7days @ 25 oC, pH 5; 7.1- 7.3days @ 25 oC, pH 7;
4.2- 10.9Hours @ 25 oC, pH 9.	MRID:

413563-33

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) indicating that Direct photolysis
is NOT an important degradation pathway.	MRID:

419316-08

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.	MRID:

419316-09

Aerobic soil metabolism	t½ = 21.3 days for two labels (R2= 0.87-0.94)
MRID:

413563-34

Anaerobic soil metabolism	t½ = 17.9-18.1 days for two labels (R2=
0.91-0.99) 	MRID:

413563-35

Aerobic aquatic metabolism	t½ =0.5-2 Days at 25 oC in the water column;
t½ = 59-77 Days at 5 oC in the water column.

Important Note: Calculated half-lives may NOT represent an aerobic
aquatic system because of exposure to light and use of diluted sediment.
	MRID:

432885-02

Adsorption/Desorption 

(Kd and Koc in L Kg-1)	Kd =  0.23; 1.36; 0.32 and 1.52 corresponding to:

Koc= 19; 55; Koc= 55; and 61	MRIDs:

413563-36

413563-37

Terrestrial Field/Lysimeter Dissipation 3	t½  (average in the top
0-3” of four soils): 5-18 Days 	MRIDs:

419316-06

419316-10

1 URL:   HYPERLINK
"http://www.scorecard.org/chemical-profiles/text-search.tcl?query_string
=Rimsulfuron" 
http://www.scorecard.org/chemical-profiles/text-search.tcl?query_string=
Rimsulfuron  

2 Solubility was reported to be 10 ppm, elsewhere; URL:  HYPERLINK
"http://www.eu-footprint.org/ppdb.html" 
http://www.eu-footprint.org/ppdb.html 

3 The terrestrial field dissipation study for a soil in Newark, Delaware
submitted under MRID 419316-10 was classified as unacceptable study.

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

ATTACHMENT No. 3: 	

Figure 1: Expected degradation scheme for rimsulfuron in the important
compartments of the environment.

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

ATTACHMENT No. 4: Example Model Runs

A. Surface Water:

RUN No. 1 FOR rimsulfuron      ON   fruit tree    * INPUT VALUES * 

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

    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP

     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)

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

   .063(   .063)   1   1      19.0    7.3   GROUND( 6.4)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 

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

     64.00        0           7.20     .00-     .00     .00       7.20

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 DEC 12, 2005

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              5.596                       .120

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

 RUN No. 2 FOR rimsulfuron      ON   fruit tree    * INPUT VALUES * 

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

    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP

     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)

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

   .031(   .054)   2  30      19.0    7.3   GROUND( 6.4)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 

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

     64.00        0           7.20     .00-     .00     .00       7.20

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 DEC 12, 2005

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

              4.786                       .103

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

App. B.  Electronic Copy of Previous Drinking Waters Analysis (cont.)

B. Ground Water:

SCIGROW

VERSION 2.3

ENVIRONMENTAL FATE AND EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS

U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL

FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

Chemical: Rimsulfuron

Time is 1/12/2007   9:20:20

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

Application      Number of       Total Use      Koc               Soil
Aerobic

rate (lb/acre)    applications     (lb/acre/yr)    (ml/g)        
metabolism (days)

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

      0.063               1.0                 0.063       5.50E+01      
          21.3

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

Groundwater screening concentration (ppb) =   1.58E-02

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

 URL:   HYPERLINK "http://www.alanwood.net/pesticides/" 
http://www.alanwood.net/pesticides/ 

 URL:   HYPERLINK
"http://www.plantprotection.org/hrac/Bindex.cfm?doc=moa2002.htm" 
http://www.plantprotection.org/hrac/Bindex.cfm?doc=moa2002.htm 

 It was not clear if the reported solubility was 7.3 or 7,300 ppm;
therefore the solubility of 7.3 ppm was assumed to be the correct
solubility as values reported elsewhere were near the 7.3 value (for
example, The solubility was reported to be 10 ppm in the EU database).

	

  PAGE   1 

	

  PAGE   

  PAGE   3 

Pyridine Ring

Pyrimidine Ring

Sulfonylurea Bridge

Parent Rimsulfuron   

@

‚

„

°

Þ

-

2

>

@

€

‚

„

Œ

’

°

Ü

h?3

h?3

%Ü

ä

(

Ü

Ý

  h?3

h?3

h?3

h?3

%

(

ô

愀Ĥ摧殿

瑹䒒/

愀Ĥ摧䒒/

愀Ĥ摧殿

愀Ĥ摧殿

愀Ĥ摧殿

˜þš

	

㓿ۖĀ̊N曾Ĵ瑹䒒/

＀￿㓿ۖĀ̊N曾Ĵ瑹䒒/

㐀ۖĀ̊N曾Ĵ瑹䒒/

hN 

hN 

hN 

@

“

a$gd

$

@

“

a$gdN 

hN 

hN 

hN 

hN 

hN 

ô

gdN 

kd

hN 

hN 

hN 

hN 

gdN 

	”

hN 

\

ꀀ将

ꀀ将

gdN 

ꀀ将

hN 

hN 

hN 

hN 

hN 

hN 

hN 

hN 

hN 

hN 

hN 

\

耀将

␃愁Ĥ摧⁎

hN 

hN 

hN 

hN 

愀Ĥ摧㔅¢

瑹㔅¢

愀Ĥ摧㔅¢

˜þš

	

˜þš

	

˜þš

	

˜þš

	

㓿ۖĀ̊N曾Ĵ瑹㔅¢

＀￿㓿ۖĀ̊N曾Ĵ瑹㔅¢

gdN 

˜þš

	

hN 

hN 

hN 

È

È

愀Ĥ摧㔅¢

愀Ĥ摧㔅¢

hN 

hN 

hN 

hN 

␃愁Ĥ摧⁎

hN 

␃愁Ĥ摧⁎

h

h

hN 

hN 

hN 

hN 

h

h

h

h

h

h

h

h

h

h

h

h

h

h

h

h

h

j

摧㔅¢Ѐ,摧⁎

 hN 

, (MINOR                       in all systems, Except as indicated)

Sulfonurea-Brigde Contraction (MAJOR       in all systems)

MAJOR in Aerobic Soil Only

IN-J290: Pyrimidine Amine

IN-E9260: Pyridine Sulfonamide

IN-70941

IN-70942

IN-T5831: Pyrimidinyl Urea