Document ID: EPA-HQ-OPP-2008-0129-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-02-27T05:00Z

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

WASHINGTON D.C., 20460

OFFICE  OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 	February 14, 2008

	PC Code: 122001

	DP Barcode D334277

MEMORANDUM

Subject: 	Tier I Sulfometuron Methyl Drinking Water Assessment for
Reregistration Eligibility Decision Document (slightly revised)

To:		John Pates, Review Manager

		Special Review and Reregistration Division (SRRD) (7505P)

From:		Michael R. Barrett, Ph.D., Senior Chemist					

		Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)		

Thru:		Mah Shamim, Ph.D., Chief					

		Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)		

This memo presents the Tier I Estimated Drinking Water Concentrations
(EDWCs) of sulfometuron methyl (CAS No. 74222-97-2), calculated using
FIRST (surface water) and SCI-GROW (ground water) for use in the human
health risk assessment.   Exposure estimates have also been generated
for the total residues of sulfometuron methyl which include sulfometuron
and major degradates such as a pyrimidine amine, a sulfonamide
degradate, and saccharin (See Appendix 1 for full chemical names and
structures).  Sulfometuron methyl is a non-selective herbicide for use
in forestry plantings, on rights-of-way, industrial sites, around
buildings, railroads, pipelines, etc.

Exposure to sulfometuron methyl parent and sulfometuron total residues
has been estimated with FIRST (FQPA Index Reservoir Screening Tool;
v.1.1.0; dated 1/1/2007) and SCI-GROW (Screening Concentration In GROund
Waterm v2.3), results are summarized below.

Parent Exposure estimates:

For surface water, the acute value is 31.98 ppb and the chronic is 14.51
ppb.  The groundwater screening concentration is 0.33 ppb. These values
represent upper-bound estimates of the concentrations that might be
found in surface water (a vulnerable reservoir) and ground water due to
the use of sulfometuron methyl at the maximum allowable rate within the
watershed.

Parent + Degradate exposure estimates:

For surface water, the acute value is 32.35 ppb and the chronic is 21.82
ppb.  The groundwater screening concentration is 1.13 ppb. These values
represent upper-bound estimates of the concentrations that might be
found in surface water (a vulnerable reservoir) and ground water due to
the use of sulfometuron methyl at the maximum allowable rate within the
watershed.

Data Gaps:

The available environmental fate studies do not provide sufficient data
for modeling of individual degradates of sulfometuron methyl that could
be of toxicological concern.  Should such estimates be required in the
future, than additional environmental fate studies specific to the
degradates of concern may be required.

Error Correction Note:

This document replaces the October 31, 2007 Drinking Water Assessment. 
The only revision is that a duplicate (and mislabeled) degradate entry
in Appendix 1 has been deleted.

Sulfometuron methyl drinking water assessment

Nature of Chemical Stressor

Sulfometuron methyl, (2-[[[[(4,6-Dimethyl-2-pyrimidinyl) amino]
carbonyl] amino] sulfonyl] benzoic acid, methyl ester), is a
broad-spectrum pre- and post-emergence herbicide that is currently
registered for weed control in forestry and non-food crop situations,
including vegetative management in right of ways and railroads.  It is
used to control a variety of broad-leaf weeds and grasses.  Similar to
other sulfonylurea herbicides, the mode of action of sulfometuron methyl
involves inhibiting the activity of the enzyme acetolactate synthase
(ALS), which in turn inhibits the synthesis of selected amino acids that
are required for cell proliferation in plants.  

Sulfometuron methyl is formulated as a water dispersible granule (WDG)
and applied using a variety of methods including helicopter, fixed-wing
aircraft, ground spray (boom and backpack) and spot treatment.  It is
generally applied once per year for non-crop areas in years that
vegetation management is needed. In some instances (weed escapes) a
second application may be made, but all products limit the total
quantity of sulfometuron methyl that may be applied (from any source) to
6 ounces of active ingredient per acre per year (0.375 lb ai/A). 
Therefore, application rates in general forestry, and for site
preparation and/or release in conifer, hardwood and Christmas tree
plantations, will vary significantly depending upon the specific purpose
of the application and the desirable tree species.  In forestry, uses
can be similar to plantation sites, but may also include the maintenance
of access routes and fire breaks.  It is further noted that use rates
can also vary with climate and soil type.  

Environmental Fate and Transport Characterization

The body of environmental fate data submitted demonstrate sulfometuron
is mobile and persistent in the environment (Appendix 2). Sulfometuron
methyl is more soluble in neutral and alkaline water than in acidic
water. The major route of dissipation for sulfometuron methyl is
believed to be aerobic and anaerobic degradation / metabolism in soil
and water (pseudo first-order degradation half-lives generally around 2
to 6 months), with hydrolysis potentially dominant under acidic
conditions. First-order rate aerobic soil metabolism half lives range
from 52 to 58 days in two laboratory studies (technically both with the
same soil type, but measured in two independent studies several years
apart).  In comparison, dissipation half-lives in the field ranged from
44 to 128 days at four sites (when considering only the residues
remaining in the upper 15 cm of topsoil). The longer persistence of
residues in the soil at one field site indicates that degradation in
some soils is slower under some field conditions than observed in many
of the laboratory studies. Sulfometuron methyl is subject to hydrolysis
at environmental pHs; with significantly more rapid hydrolysis occurring
under acidic conditions (e.g., a hydrolysis half-life of 9 days at pH 5
and 139 days at pH 7).  However, laboratory and field studies in soil or
sediment / water environments, albeit all at measured pHs somewhat
greater than 5, do not generally show as rapid degradation as measured
in the pH hydrolysis study.

.  

Metabolism in the aquatic environment is variable, ranging from
half-life of 17 to 104 days in anaerobic conditions and 9 to 187 days
for aerobic conditions (the more rapid degradation with a 9-day total
system half-life took place in a test system with sediment pH of 5.4 and
water pH of 7.6).  Although sulfometuron methyl persistence is expected
to generally increase with higher soil pH (rotational crop restrictions
for many other sulfonylureas, which are all weak acids, reflect this), a
consistent trend was not found in the available studies.  

Soil retention of sulfometuron methyl is low, with Freundlich adsorption
KF values ranging between 0.15 and 2.1 ml/g in four test soils with soil
organic carbon content ranging between 0.6 and 2.6 percent.

Sorption was not found to be strongly dependent on any of the major
properties of the tested soils in the registrant-submitted studies. The
pKa of sulfometuron methyl is 5.4, and theoretically, adsorption may
increase in very acidic soils where the methyl ester form of
sulfometuron would predominate.  However, the pH range of the four test
soils in the batch equilibrium adsorption / desorption study was only
6.7 to 7.7. The published literature do seem to show more of a
relationship of sulfometuron methyl and other sulfonylureas to mobility
in soil; Weber et al. (2004) have reviewed the literature and concluded
that there is a consistent relationship between pH and mobility of
sulfonylureas (“NHSO2 acid herbicides” means sulfonylurea
herbicides):

OM and pH were also the primary soil properties in best-fit Kd equations
obtained for five of the six NHSO2 acid herbicides, with all three soil
properties utilized in the Kd equation for sulfometuron-methyl. Cl was
also one component of the Kd equation for sulfometuron-methyl, but Cl
and pH were also related soil properties. As was the case for the COOH
acid herbicides, sorption increased as OM increased or as pH decreased.

Other abbreviations used in the above excerpt from the Weber et al.
article:

OM = Soil organic mater content

Cl = Chloride ion concentration

COOH acid herbicides = Herbicides with a carboxy acid functional group
such as 2,4-D and Imazethapyr

In terrestrial field dissipation studies at four US sites, leaching of
parent sulfometuron methyl occurred at measurable concentrations (>10
ppb in depth increments from 15 to 90 cm) was noted at each test site.
Leaching of the degradates was not evaluated in the field dissipation
studies.

Sulfometuron persistence in water indicates that if, either via spray
drift or any runoff event, sulfometuron methyl reaches surface water, it
may persist for a few weeks to several months and present some concern
to surface water resources.  The fairly low use rate (maximum annual
rate of 0.375 lb ai/A) and the apparent typical use pattern of applying
in only one or two years out of a several year period should limit the
actual exposure of sulfometuron methyl residues in surface water
(however, note that sulfometuron methyl could negatively affect certain
sensitive plants at very low exposure levels because it is such a potent
herbicide with respect to many plant species).  

Volatility studies were not reported.  However, based its chemical
properties, volatilization is not expected to be a route of dissipation
of sulfometuron methyl in water or soils.   

Sulfometuron methyl degrades to CO2 under aerobic, non-sterile
conditions (relatively little mineralization occurs under sterile
conditions), but with significant accumulation of intermediate
degradates, including a sulfonamide and saccharin from the phenyl ring
part of the parent molecule and a pyrimidine amine from the pyrimidine
ring portion (see Appendix 1). For the phenyl ring labeled studies, CO2
was up to 28 to 44 % of applied at study termination whereas for the
pyrimidine-ring labeled studies CO2 was up to 53% of applied at study. 

The only submitted studies directly evaluating the fate of sulfometuron
methyl degradates were adsorption / desorption studies on the pyrimidine
amine and saccharin. The soil retention characteristics of two of the
sulfometuron methyl degradates were studied in batch equilibrium
adsorption / desorption studies: saccharin Kfs were 0.03 to 0.27 and the
pyrimidine amine Kfs were 0.17 to 3.70 in the four test soils. This
means saccharin would be slightly more mobile and the pyrimidine amine
slightly less mobile than parent (Kfs of 0.15 to 2.12 in the same four
soils)

Drinking Water Exposure Estimation

While some monitoring data are available, the data are not targeted to
watersheds known to present the highest exposure potential for
sulfometuron methyl.  Consequently, EFED’s Tier I models were used for
this drinking water exposure assessment.

Model Descriptions

Surface Water:  The FIRST (FQPA Index Reservoir Screening Tool, Version
1.1.0) model by the Environmental Fate and Effects Division (EFED) of
the USEPA Office of Pesticide Programs (OPP) was used to assess
potential for contamination of surface drinking water sources from the
proposed sulfometuron methyl use.  

FIRST is a single-event model (one runoff event), but can account for
spray drift from multiple applications.  FIRST is hardwired to represent
the Index Reservoir, a standard water body used by the Office of
Pesticide Programs to assess drinking water exposure (Office of
Pesticide Programs, 2002).  It was based on a real reservoir, Shipman
City Lake in Illinois, which was known to be vulnerable to pesticide
contamination (with ample confirmation from pesticide monitoring data).
The single runoff event moves a maximum of 8% of the applied pesticide
into the reservoir.  This amount can be reduced due to degradation on
the field and the effects of binding to soil in the field.  FIRST also
uses a Percent Cropped Area (PCA) factor to adjust for the area within
the watershed that is planted to the modeled crop.  The national default
PCA of 0.87 was applied in this assessment.

Ground Water:  Sulfometuron methyl concentrations in ground water were
estimated by the Screening Concentration in Ground Water (SCI-GROW v2.3,
Jul. 29, 2003) model.  SCI-GROW is a regression model used as a
screening tool to estimate pesticide concentrations found in groundwater
used as drinking water.  SCI-GROW was developed by fitting a linear
model to ground water 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
SCI-GROW represents the concentrations sulfometuron methyl residues that
might be expected in shallow unconfined aquifers under sandy soils. 

Further information on these models can be found at the EFED water model
website at http://   HYPERLINK
"http://www.epa.gov/oppefed1/models/water/html" 
www.epa.gov/oppefed1/models/water/html .

Model Inputs and Results (Drinking Water Estimated Concentrations)

Key inputs for FIRST modeling, including data sources and parameter
estimation methods (if applicable) are summarized in   REF _Ref177972956
\h  Table 1  and results for parent sulfometuron methyl are given in  
REF _Ref181591758 \h  Table 3  and for the total residues in   REF
_Ref181591770 \h  Table 4 .  These are conservative estimates, in most
cases the potential exposure will be lower because the fraction of
watershed land which represents legally possible sulfometuron methyl use
sites, and furthermore,  represents actual sulfometuron methyl use sites
in any given year is smaller than 0.87, the default percent crop (or use
site) area that needs to be used. 

For ground water, SCI-GROW modeling inputs are presented in   REF
_Ref178394075 \h  Table 2  and Tier I estimated concentrations for
drinking water arising from ground water are provided for parent
compound in   REF _Ref181591758 \h  Table 3  and for total residues in  
REF _Ref181591770 \h  Table 4 .  The predicted exposure levels are lower
than for surface water sources for drinking water.

Care needs to be used in assessing risk to sulfometuron total residues
including degradates from the DWECs presented here. The nature of the
total residue modeling method means that the total residues are
estimated as parent equivalents.  Similar weight / volume drinking water
estimated concentrations for individual degradates which arise from
fractionation of the parent molecule would be substantially less (if
they could be calculated from the available environmental fate data). 
Given the limited environmental fate data on the degradates, no
estimation of individual degradate concentrations is possible at this
time.  The DWECs in these tables cannot be manipulated to provide
separate degradate and parent concentrations. 

Table   SEQ Table \* ARABIC  1 .  FIRST input parameters for modeling
(DWECs).

Input Parameter	Value*	Reference

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

Vapor Pressure (torr)	5.4x10-16

	Aerobic Soil Metabolism Half-life (days)	61	90% Upper Confidence Limit
of the mean of measured values  (MRIDs 42091401; 43174102 and 245375)

Water column Half-life (days)

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

Benthic sediment Half-life (days) 

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

Application Rate (lb a.i. / A)	Up to 0.375	Efficiency= 0.99 for ground
spray, 0.95 for aerial.

Application Number (Method of application)	    One, two or three 
Product Label; typical use. Maximum annual rate of 0.375 lb ai/ A was
used in each case.

Application method; Depth of Incorporation (cm)	Aerial: NA 

Ground: 0	Product Label; typical use.

Spray Drift (fraction)	0.16 (GS), 0.064 (aerial)	Default values for the
FIRST model. (GS= ground spray) – Not a user input.

Solubility (ppm)	244	Highest solubility was recorded for alkaline water
(12,500 ppm at pH 8.6).  However, experience from other studies
indicates these experimental values are too high.

Koc (L Kg-1)	35	Lowest Koc value of the three non-sand soils tested
(MRID 42789301). Koc model was determined to be appropriate.

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

MRID 42715201. 

Direct Aqueous Photolysis Half-life(days)	Stable	Maximum dark control
corrected value (MRIDs 42182401 and 43174101)

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

Table   SEQ Table \* ARABIC  2 . SCI-GROW modeling inputs.

Input Parameter	Value*	Reference

Aerobic Soil Metabolism Half-life (days)	55.2

(136 for total residues)	Mean of measured values  (MRIDs 42091401;
43174102 and 245375)

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

Application Number (Method of application)	    One	Typical use.

Koc (L Kg-1)	73.4

(same for total residues)	Median of four values (MRID 42789301). 

Table   SEQ Table \* ARABIC  3 .  Tier I EDWCs for sulfometuron methyl
from forestry or rights of way uses.

		Chemical	Application	Peak Day (Acute)	Annual Average (Chronic)

Surface Water	 Rate (lb a.i./A)	   Number  	Interval 	Concentration
(µg/L)

Aerial	0.375 	1	NA	31.96	14.51

Ground	0.375 	1	NA	31.98	14.50

Aerial	0.188	2	30	27.57	12.52

Aerial	0.125	3	90	16.53	7.5

Aerial	0.125	3	45	21.39	9.7

Ground Water

	Aerial or ground	0.375	1	NA	0.33	0.33

Table   SEQ Table \* ARABIC  4 . Tier I EDWCs for sulfometuron total
residues from forestry or rights of way uses*.

Chemical	Application	Peak Day (Acute)	Annual Average (Chronic)

Surface Water	 Rate (lb a.i./A)	   Number  	Interval 	Concentration
(µg/L)

Aerial	0.375 	1	NA	32.35	21.82

Aerial	0.188	2	30	30.21	20.38

Ground Water

	Aerial or ground	0.375	1	NA	1.13	1.13

* Includes sulfometuron methyl, sulfometuron free acid, sulfometuron
pyrimidine amine, sulfometuron sulfonamide, and saccharin.

Review of Monitoring Data

In the most widespread monitoring survey available, sulfometuron methyl
was detected only rarely (2 of 132 samples from 52 sites – mostly
Midwestern US streams and rivers, but including some reservoirs as
well); see Battaglin et al. (2000).  The maximum concentration of
sulfometuron methyl detected was 0.018 ug/L; but it is not known how
much sulfometuron methyl usage was associated with the watersheds
included in this monitoring survey.  

Blomquist et al. (2001) in a monitoring study of 12 reservoir systems
across the United States found sulfometuron methyl occurred above the
minimum reporting limit of 0.05 ug/L in 12% of the samples collected
with a maximum concentration of 0.16 ug/L and a 95th percentile
concentration of 0.10 ug/L.  This study focused on drinking water
supplies and the results are directly relevant to this drinking water
assessment; however these data cannot be used for a conservative
(protective) estimate of drinking water exposure since there is no basis
to conclude that the study sites represent watersheds where exposure to
sulfometuron methyl is the highest.

APPENDIX 1: Structures and Chemical Names of Sulfometuron methyl
Metabolites

Chemical Structures

Trivial or common names

Company id or similar alternate names

Full chemical names

Sulfometuron methyl

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

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

	

Saccharin

IN-581

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

Sulfometuron pyrimidine amine

IN-X0993; IN-X993; PA

4,6-Dimethyl-2-pyrimidinamine

4,6-dimethyl-2-pyrimidinamine

	

Sulfometuron sulfonamide

IN-D5803; SA; methyl phenylsulfonamide

Methyl 2-(aminosulfonyl)benzoate.

2-(Aminosulfonyl)-benzoic acid, methyl ester

Pyrimidine-ol

IN-11859

4,6-Dimethyl-2-pyrimidinol	

Sulfometuron free acid

FA-SM; IN-T6385

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

Free acid Sulfonamide

FA-Sulfonamide; Free acid; IN-D5119

2-(Aminosulfonyl)benzoic acid

	

APPENDIX 2: Environmental Fate Summary Table

Table   SEQ Table \* ARABIC  5 . Key results of sulfometuron methyl
environmental fates studies.

Parameter

[Guideline #]	Value1	MRID(s)

Hydrolysis

[161-1]

	t½= 8.8 days (LL) @ 25 oC, pH 5;

t½=139 days (LL) @ 25 oC, pH 7;

t½= 224 days (LL) @ 25 oC, pH 9.

	

Major degradates (from cleavage of the sulfonylurea bridge): 

Sulfonamide – only in acidic water

Saccharin – all pH levels

Pyrimidine amine – all pH levels

	

42715201

Direct photolysis in water

[161-2]	Combined labels results:

t½= 428 days (LL) @ 24 oC, pH 5;

t½= stable @ 24 oC, pH 7;

t½= stable @ 24 oC, pH 9.

(calculated by the difference in degradation rates between irradiated
and dark controls and adjusting for typical light levels on sunny days)

Major degradates (irradiated water):

pH 5:  sulfonamide, pyrimidine amine;

pH 7:  none;

pH 9:  none.

	

42182401

43174101

Photolysis on soil

[161-3]	t½= 72.1 days (LL) @ 25 oC, 

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

Major degradates (from cleavage of the sulfonylurea bridge):

Saccharin reached a maximum of 48.4% of the applied at 33 days (study
termination.)

Pyrimidine amine reached a maximum of 53.1% at 33 days (study
termination.)

There was no substantial difference in the degradation pathway of
sulfometuron methyl between the irradiated- and the dark control soil.

No other degradate accounted for >4% of the applied radioactivity
regardless of whether the phenyl ring or the pyrimidine ring was
14C-labeled.	

41420601

Aerobic soil metabolism

[162-1]

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

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

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

Observed DT50:		23 days.

Observed DT90:		110 days.

Sterile soil First Order t½: 	364 days (LL)

Major transformation products:

Pyrimidine amine (maximum 41.0% of the applied)

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

	CO2 (maximum 53.1% of applied).

Minor transformation products:	

Free acid sulfometuron methyl.

Pyrimidine urea. 

	

42091401

Aerobic soil metabolism

[162-1]

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

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

First Order t½:		52.5 days (LL) (r2 = 0.9239).

Observed DT50:	29 days.

Observed DT90:	162 days.

Major transformation products:

Sulfonamide.

Saccharin.

Free acid sulfonamide plus urea (1.0 mg a.i./Kg only).

	CO2.

Minor transformation products:	

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

	

43174102 and 245375

Anaerobic aquatic metabolism

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

Matrix: Bradenton Pond water-sand sediment.

First Order t½:			37.4 days (LL) (r2 = 0.6125).

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

Observed total system DT90:	102 days.

Matrix: Landenberg Pond water-sandy loam sediment.

First Order t½; total system:	17.1 days (LL) (r2 = 0. 0.6394).

Observed total system DT50:	6.1 days.

Observed total system DT90:	21.7 days.

Major transformation products (both systems):

free acid sulfometuron methyl.

pyrimidine amine.

Minor identified transformation products:

pyrimidine-ol.

CO2.	

42091402 and 43188601

Anaerobic aquatic metabolism

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

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

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

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

Observed DT50 in total system:	ca. 21 days.

Sterile t½; total system:	44 days (LL)

* Based upon limited and inconsistent data.

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

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

First Order t½; total system:	87 days (LL) (r2 = 0.3577).

Observed DT50 in total system:	ca. 28 days.

Sterile t½; total system:	175 days (LL)

Matrix: Pond water-loam sediment from Saskatoon, Canada. (water pH 8.3 .
  Sediment: pH 7.8; O.C. = 0.9 %).

First Order t½; total system:	77 days (LL) (r2 = 0.5853).

Observed DT50 in total system:	ca. 70 days.

Sterile t½; total system:	399 days (LL)

Matrix: Pond water-silt loam sediment from Walnut Grove, Tennessee.
(water pH 5.5 .   Sediment: pH 5.1; O.C. = 0.5 %).

First Order t½; total system:	73 days (LL) (r2 = 0.5691).

Observed DT50 in total system:	ca. 28 days.

Sterile t½; total system:	95 days (LL)

Major transformation products:

	saccharin.

	free acid sulfonamide.

Minor identified transformation products:

	Methyl-2-aminocarbonyl(aminosulfonyl)benzoate.	

4413010-20 (143540)

Aerobic aquatic metabolism

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

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

First Order t½; total system:	9.2 days (LL) (r2 = 0.94).

Observed DT50 in total system:	15 days.

Observed DT90 in total system:	31 days (extrapolated).

Major transformation products:

Pyrimidine amine (pyrimidine label).

Hydroxymethyl-pyrimidine sulfometuron methyl.

Free acid sulfonamide (phenyl label).

Sulfonamide (phenyl label).

Minor identified transformation products:

CO2.

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

First Order t½; total system:	187.3 days (LL) (r2 = 0.5713).

Observed DT50 in total system:	>39 days.

Major transformation products:

Pyrimidine amine (pyrimidine label).

Free acid sulfonamide (phenyl label).

Minor identified transformation products:

Hydroxymethyl-pyrimidine sulfometuron methyl.

Sulfonamide (phenyl label).

CO2.	

42091403 and 43174103

Adsorption/

Desorption 

(Kd and 

Koc in L Kg-1)

	Parent sulfometuron methyl:

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

Adsorption Kd:			0.35.

Adsorption Koc:			35.

Freundlich adsorption KF:	0.153.

Freundlich adsorption KFoc:	14.7.

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

Adsorption Kd:			2.07.

Adsorption Koc:			79.6.

Freundlich adsorption KF:	2.12.

Freundlich adsorption KFoc:	83.2.

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

Adsorption Kd:			Not applicable.

Adsorption Koc:			Not applicable.  

Freundlich adsorption KF:	0.508.

Freundlich adsorption KFoc:	87.6.

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

Adsorption Kd:			0.79.

Adsorption Koc:			52.7.

Freundlich adsorption KF:	0.974.

Freundlich adsorption KFoc:	67.2.

	42789301

Adsorption/

Desorption 

Of Degradates	

  SEQ CHAPTER \h \r 1 Pyrimidine amine

Soil type:  Chino Sandy loam.

Freundlich adsorption   KF:  3.3.

Freundlich adsorption KFoc:  315.

Soil type:  Fargo Silt loam.

Freundlich adsorption KF: 3.7.

Freundlich adsorption KFoc:  145.

Soil type:  Miaka Sand.

Freundlich adsorption KF:	0.17.

Freundlich adsorption KFoc:  29.4.

Soil type:  Tama Silt loam.

Freundlich adsorption KF:	2.9.

Freundlich adsorption KFoc:  203.

  SEQ CHAPTER \h \r 1 Results Synopsis: [14C]Saccharin

Soil type:  Chino Sandy loam.

Freundlich adsorption KF:	0.11.

Freundlich adsorption KFoc:  10.5.

Soil type:  Fargo silt loam.

Freundlich adsorption KF:	0.27.

Freundlich adsorption KFoc:  10.6.

 Soil type:  Miaka Sand.

Freundlich adsorption KF:	0.033.

Freundlich adsorption KFoc:  5.73.

Soil type:  Tama Silt loam.

Freundlich adsorption KF:	0.13.

Freundlich adsorption KFoc:  8.72.

	

42789301

Terrestrial Field/Lysimeter

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

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

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

DT90:	32 days

Major transformation products detected (>0.01 ppm): 

Sulfometuron free acid (SFA)

Pyrimdine amine (PYA)

Sulfonamide IN-D5803 (SFN)

Saccharin IN-581 (SCC)

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

Half-life: 128 days (based on 0- to 723-day data, residues in 0-15 cm
depth only); 

14.4 days (based on 0- to 90-day data).

DT90:	35 days

Major transformation products detected (>0.01 ppm): 

PYA, SFN, and SCC

Uvale, TX clay soil: pH 7.9, 1.3% O.C.

Half-life:  53.3 days (LL) (based on 0- to 447-day data); 

13.0 days (LL) (based on 0- to 90-day data).

DT90:	25 days

Major transformation products detected (>0.01 ppm): 

PYA, SFN, and SCC 

Maldera, CA sandy loam soil: pH 7.8, 0.7% O.C.

Half-life: 44.1 days (LL) (based on 0- to 420-day data); 

22.9 days (LL) (based on 0- to 180-day data).

DT90:	55 days

Major transformation products detected (>0.01 ppm):

PYA, SFN, and SCC	Numbers 43212101 and 43637101

1 LL = “Log-linear” degradation rate calculation; process of
calculating degradation rates and half-lives from linear regression of
log-transformed concentration measurements over time. This provides a
first-order type of measurement of pesticide decline.

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

APPENDIX 3: Modeling Input and Output

FIRST Modeling Input and Output Files

Sulfometuron methyl parent, Single application, Aerial.

RUN No.   1 FOR Sulfometuron met ON   Forest        * INPUT VALUES * 

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

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

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

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

   .375(   .375)   1   1      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

     61.00        2          N/A       .00-     .00   292.00    292.00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             31.962                     14.508

Sulfometuron methyl parent, Single application, Ground.

   RUN No.   3 FOR Sulfometuron met ON   Forest - G    * INPUT VALUES * 

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

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

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

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

   .375(   .375)   1   1      35.0  244.0   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.) 

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

     61.00        2          N/A       .00-     .00   292.00    292.00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             31.980                     14.500

Sulfometuron methyl parent, 2 applications, Aerial.

   RUN No.   8 FOR Sulfometuron met ON   Forest - A    * INPUT VALUES * 

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

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

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

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

   .188(   .321)   2  30      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

     61.00        2          N/A       .00-     .00   292.00    292.00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             27.573                     12.519

Sulfometuron methyl parent, 3 applications, 90-day interval,  Aerial.

   RUN No.  10 FOR Sulfometuron met ON   Forest - a    * INPUT VALUES * 

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

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

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

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

   .125(   .186)   3  90      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

     61.00        2          N/A       .00-     .00   292.00    292.00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             16.532                      7.512

Sulfometuron methyl parent, 3 applications, 45-day interval,  Aerial.

   RUN No.  11 FOR Sulfometuron met ON   Forest aer    * INPUT VALUES * 

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

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

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

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

   .125(   .245)   3  45      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

     61.00        2          N/A       .00-     .00   292.00    292.00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

9.715

Sulfometuron methyl total residues, Single application, Aerial.

RUN No.  12 FOR Sulfometuron Tot ON   Forest        * INPUT VALUES * 

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

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

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

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

   .375(   .375)   1   1      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

    136.00        2          N/A       .00-     .00      .00       .00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             32.354                     21.819

Sulfometuron methyl total residues, 2 applications, 30 day interval,
Aerial.

   RUN No.  13 FOR Sulfometuron Tot ON   Forest        * INPUT VALUES * 

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

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

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

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

   .188(   .348)   2  30      35.0  244.0   AERIAL(16.0)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

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

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

    136.00        2          N/A       .00-     .00      .00       .00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0  JAN 1, 2007

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

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

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

             30.208                     20.375

SCI-GROW Modeling Input and Output Files

                   SCIGROW VERSION 2.3

            ENVIRONMENTAL FATE AND EFFECTS DIVISION

                 OFFICE OF PESTICIDE PROGRAMS

             U.S. ENVIRONMENTAL PROTECTION AGENCY

                        SCREENING MODEL

                FOR AQUATIC PESTICIDE EXPOSURE

Parent Compound:

SciGrow version 2.3

 chemical:Sulfometuron Total Resides

 time is 10/31/2007  12:30:46

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.375           1.0           0.375      7.34E+01       55.2

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

 groundwater screening cond (ppb) =   3.29E-01 

 ***********************************************************************
*

 

Total Residues:

 SciGrow version 2.3

 chemical:Sulfometuron Total Residues

 time is 10/ 4/2007  14:16:15

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

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

      0.375           1.0           0.375      7.34E+01      136.0

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

 groundwater screening cond (ppb) =   1.13E+00 

 ***********************************************************************
*

  Weber, J.B., G.G. Wilkersona and C.F. Reinhardt. 2004 Calculating
pesticide sorption coefficients (Kd) using selected soil properties. 
Chemosphere 55:157–166

  Battaglin, WA, Furlongb, ET,  Burkhardt, MR, Peter, CJ. 2000.
Occurrence of sulfonylurea, sulfonamide, imidazolinone, and other
herbicides in rivers, reservoirs and ground water in the Midwestern
United States. Sci. Tot. Environ. 248: 123-133

  Blomquist, J.D., Denis, J.M., Hetrick, J.A., Jones, R.D., and
Birchfield, N.B. (2001) Pesticides in selected water-supply reservoirs
and finished drinking water, 1999-2000; summary of results from a pilot
monitoring program: U.S. Geological Survey Open-File Report 01-0456, 65
p.

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