Document ID: EPA-HQ-OPP-2009-0057-0008
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-04-07T04:00Z

U. S. ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, DC 20460

.	OFFICE OF             

	PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES 

										December 8, 2009

MEMORANDUM 						

SUBJECT:	Estimated Environmental Concentrations of Nicosulfuron, for Use
on Bermuda Grass in Human Health Risk Assessment 

		(PC Code 129008; DP Barcode  D360831)

FROM:	Larry Liu, Ph.D., Environmental Scientist				

Environmental Risk Branch 5

Environmental Fate and Effects Division

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

Environmental Risk Branch 5

Environmental Fate and Effects Division 

TO:		James Tompkins

Registration Division

This memo presents the Tier I Estimated Environmental Concentrations
(EECs) for nicosulfuron, estimated using PRZM/EXAMS for surface water
and SCIGROW for groundwater in the human health risk assessment.

For nicosulfuron, the surface water acute (peak) value is 0.52 ppb and
the chronic value is 0.10 ppb based on the application on Bermudagrass
pastures. The groundwater screening concentration is 0.08 ppb for
nicosulfuron.  Details of the application scenarios that were evaluated
are presented below.

Use Characterization

The registrant is seeking a FIFRA Section 3 for the use of nicosulfuron
as a herbicide on Bermudagrass pastures.  The target pests and relevant
application information are summarized in Table 1.  

Table 1. Use information for the proposed use of nicosulfuron on Bermuda
grass pastures.

Target Pests	Single Application Rate (lb a.i./acre)	Maximum Seasonal
Rate

(lb ai/acre)	Maximum Number Applications Per Season	Minimum Application
Interval (Days)	Application Methods

Weeds 	0.035-0.053	0.088	2	Not specified	Aerial or Ground equipment

Bermuda grass is a warm season sodding, creeping perennial grass.  It
can be found on millions of acres throughout the US, mainly in the
southern states.  Since pasture is the primary source for grazing
animals such as cattles, two of the top five states for cattle
productions (Texas and Oklahoma) in the southern US were selected in the
drinking water assessment.

Environmental Persistence

Nicosulfuron degrades slowly under laboratory and field conditions, with
the apparent primary route of dissipation in the field being leaching
coupled with soil metabolism at the soil surface.

The majority of the fate studies were reviewed in1990 (see details in
the EFED review “DPR-V9360 (Sulfonyurea herbicide) - New Chemical
Accent (Trade Name); Terrestrial Food Crop Uses (Corn)”; dated
2/22/90).   Since 1990, the registrant has submitted two studies: an
aerobic soil metabolism study and a terrestrial field dissipation study.

Nicosulfuron has very high mobility in soils ranging from sandy loam to
silt loam, with Freundlich adsorption coefficients of 0.7 (or Koc = 35).
 However, the mobility of its two major degradates (pyridine sulfonamide
and pyrimidne amine) in the environment is unknown because no
information are available. Results from the field dissipation study are
consistent with the above prediction regarding the relative mobility of
the above three chemicals.  At the Illinois study site (silty clay loam;
soil pH = 6.0; and organic matter = 4.7%), nicosulfuron, pyridine
sulfonamide, pyrimidine amine were detected in the 0-6 inch zone whereas
only pyridine sulfonamide was found in the 6-12 inch zone.  At the
California study site (sandy loam; soil pH = 7.8; and organic matter =
4.7%), nicosulfuron, pyridine sulfonamide, pyrimidine amine were
detected in the 0-6 inch zone whereas only the parent compound and
pyridine sulfonamide were found in the 6-12 inch zone. The movement of
pyridine sulfonamide from the surface to the deeper zone was likely due
to the sandy nature of the soil at the California site.

Volatilization is not expected to be significant since the reported
vapor pressure is 1.2 E-6 torr. 

The primary degradation pathway was aerobic soil metabolism.  Based on
the aerobic soil metabolism studies reviewed (MRIDs 41082262 and
46240901; the first study was reviewed on February 19, 1990), it
appeared that the degradation rate and the resulting degradates under
aerobic soil metabolism conditions depended on the pH of the soil. 
Nicosulfuron appeared to be more persistent in alkaline soils (i.e.,
half-life 35.9 days) than in acidic soils (i.e., half-life 26 days). 
Although the half-life observed from the field dissipation study
conducted in California (with a soil pH 7.1) was slightly longer than
that observed from the study conducted in Illinois (with a soil pH 6.0),
based on the requirements for longer rotational crop intervals for more
alkaline soils than less alkaline soils (as well as more neutral soils
than more acidic soils) as stated in the labels, it would be reasonable
to expect that the parent compound and/or its degradates would be more
persistent as the pH of the soil increased.

In acidic soil (MRID 41082262), the major degradates were pyridine
sulfonamide (87.4% and 92.9% of the applied at 120 and 240 days,
respectively, after application) and pyrimidine amine (72.8% and 80.7%
at the corresponding period).  In neutral/alkaline soil (MRID 46240901),
the major degradates were pyridine sulfonamide (18 % of the applied at
120 days after application) and IN-HYY21 (17% of the applied at 120 days
after application).

Rotational crop studies submitted indicate that nicosulfuron residues
may exhibit phytotoxic effects even after a 10-month rotation.  This
phytotoxic effect could be worsened by site soil characteristics
(alkaline soils that favor persistence) and/or climatic conditions
(colder climates; dry climates) that slow down the degradation of
nicosulfuron.  Table 2 includes the environmental fate properties for
nicosulfuron.

Table 2. Summary of Fate Properties for Nicosulfuron.

Study Type	

Half-Life/Kd/Koc	MRID

Hydrolysis (pH 5)	

15 days	40924220

Hydrolysis (pH 7)	

stable

	

Hydrolysis (pH 9)	

stable

	

Aqueous photolysis (pH 7)	

250 days	41082620

Aqueous photolysis (pH 9)	

200 days

	

Soil Photolysis	

67 days	41082621

Aerobic Soil	

26 and 35.9 days	40924222, 46240901

Anaerobic Soil	

63 days	41082623

Adsorption	

Kd/Koc

   sandy loam	

0.16/25.2	40924222

   sandy loam 	

0.28/23.0

	

   silt loam	

1.73/69.4

	

   sit loam	

0.61/22.4

	

Field Dissipation	

Illinois (lysimeters/bare ground) - 108 days (pyridine radiolabeled)

Illinois (lysimeters/bare ground) - 120 days (pyrimidine radiolabeled)

California (lysimeters/bare ground) - 114 days (pyridine radiolabeled)

Californis (lysimeters/bare ground) - 120 days (pyrimidine radiolabeled)
41082604, 43483901

Listed below are the product chemistry information for nicosulfuron:

Water solubility (28 C)    = 	390 ppm (pH 5.1-5.6)

9,000 ppm (pH 6.3)	

18,000 ppm (pH 7.2)

> 250,000 ppm (pH 9.0)

Vapor pressure = 1.2x10-16 torr

Kow = 0.017 (pH 7)

Expected Mobility

Nicosulfuron has very high mobility in soils ranging from sandy loam to
silt loam, with Freundlich adsorption coefficients of 0.7 (or Koc = 35).
 However, the mobility of its two major degradates (pyridine sulfonamide
and pyrimidne amine) in the environment is unknown because no
information are available.  Based on the results from an unacceptable
TLC study submitted in 1990, it appears that pyridine sulfonamide is
more mobile than the parent compound whereas pyrimidne amine is less
mobile than the parent compound.  Results from the field dissipation
study are consistent with the above prediction regarding the relative
mobility of the above three chemicals.  At the Illinois study site
(silty clay loam; soil pH = 6.0; and organic matter = 4.7%),
nicosulfuron, pyridine sulfonamide, pyrimidine amine were detected in
the 0-6 inch zone whereas only pyridine sulfonamide was found in the
6-12 inch zone.  At the California study site (sandy loam; soil pH =
7.8; and organic matter = 4.7%), nicosulfuron, pyridine sulfonamide,
pyrimidine amine were detected in the 0-6 inch zone whereas only the
parent compound and pyridine sulfonamide were found in the 6-12 inch
zone. The movement of pyridine sulfonamide from the surface to the
deeper zone was likely due to the sandy nature of the soil at the
California site.

Volatilization is not expected to be a significant since the reported
vapor pressure is 1.2 x 10-16 torr. 

Degradate Profile

The primary degradation pathway was aerobic soil metabolism.  Based on
the aerobic soil metabolism studies reviewed (MRIDs 41082262 and
46240901; the first study was reviewed on February 19, 1990), it
appeared that the degradation rate and the resulting degradates under
aerobic soil metabolism conditions depended on the pH of the soil. 
Nicosulfuron appeared to be more persistent in the alkaline soils (i.e.,
half-life 35.9 days) than in the acidic soils (i.e., half-life 26 days).
 Although the half-life observed from the field dissipation study
conducted in California (with a soil pH 7.1) was slightly longer than
that observed from the study conducted in Illinois (with a soil pH 6.0),
based on the requirements for longer rotational crop intervals for more
alkaline soils than less alkaline soils (as well as more neutral soils
than more acidic soils) as stated in the labels, it would be reasonable
to expect that the parent compound and/or its degradates would be more
persistent as the pH of the soil increased.

In acidic soil (MRID 41082262), the major degradates were pyridine
sulfonamide (87.4% and 92.9% of the applied at 120 and 240 days,
respectively, after application) and pyrimidine amine (72.8% and 80.7%
at the corresponding period).  In neutral/alkaline soil (MRID 46240901),
the major degradates were pyridine sulfonamide (18 % of the applied at
120 days after application) and IN-HYY21 (17% of the applied at 120 days
after application).  However, results from the above aerobic soil
metabolism studies could not be used to assess quantitatively the fate
of the major degradates in the water assessment for the following
reasons:

1.  Aerobic soil metabolism study (conducted in 1989 and reviewed in
1990; MRID 41082262) - the study was terminated at 240 days before
patterns of formation and decline of the major degradates were
established.

2. Aerobic soil metabolism study (conducted in 2004 and reviewed in
2004; MRID 46240901) - the study was terminated at 120 days before
patterns of decline of the parent compound and patterns of formation and
decline of major degradates were established.

PRZM/EXAMS for Surface Water

The exposure assessment for this proposed new nicosulfuron use was based
on estimated environmental concentration (EECs) in surface water
resulting from application of nicosulfuron to Bermuda grass pasture and
hayfields when used according to the proposed label.  Since the label
did not specify the application interval between two applications, EFED
used the same 14 days as in the Estimated Environmental Concentration of
Nicosulfuron for Use on Pasture in Ecological Risk Assessment.  Model
inputs were selected consistent with those used in the 2004 drinking
water assessment and are summarized in Table 3.  Copy of the model
output for the drinking water is presented in Appendix 1.

Table 3. Summary of PRZM/EZAMS environmental fate data used for drinking
water assessment inputs for nicosulfuron.

Fate Property	Value	Source

Molecular Weight	410.4 g/mol	Product chemistry

Vapor Pressure	1.2 x 10-6 torr	Product chemistry

Solubility in Water	12,000 mg/l	Product chemistry

Photolysis in Water	250 days	EFED guidancea

Aerobic Soil Metabolism Half-life	31.9 days	EFED guidancea  

Hydrolysis	stable	EFED guidancea  

Aerobic Aquatic Metabolism (water column)	16 days	EFED guidancea  

Anaerobic Aquatic Metabolism (benthic)	31.5 days	EFED guidancea  

Koc	35	EFED guidancea  

Application Efficiency	95 % for aerial

99 % for ground	EFED guidancea 

Spray Drift Fraction	16 % for aerial for DWA

6.4 % for ground for DWA	EFED guidancea 

a  Inputs determined in accordance with EFED “Guidance for Chemistry
and Management Practice Input Parameters for Use in Modeling the
Environmental Fate and Transport of Pesticides” dated February 28,
2002.

SCI-GROW for Groundwater

SCI-GROW provides a groundwater screening exposure value to be used in
determining the potential risk to human health from drinking water
contaminated with the pesticide.  Since the SCI-GROW concentrations are
likely to be approached in only a very small percentage of drinking
water sources, i.e., highly vulnerable aquifers, it is not appropriate
to use SCI-GROW for national or regional exposure estimates.  SCI-GROW
estimates likely groundwater concentrations if the pesticide is used at
the maximum allowable rate in areas where groundwater is exceptionally
vulnerable to contamination.  In most cases, a large majority of the use
area will have groundwater that is less vulnerable to contamination than
the areas used to derive the SCIGROW estimate.  Input parameter used in
SCI-GROW are presented in Table 4. Copy of the model output for the
drinking water is presented in Appendix 2.

Table 4.  Environmental Fate Input Parameters for SCI-GROW.

Parameter	

Nicosulfuron Value

Organic Carbon Partition Coefficient (KOC)	

24.01

Aerobic Soil Metabolism Half-Life	

31.0 days

Drinking Water Exposure Assessment

By design, all existing PRZM scenarios are intended to represent
high-end exposure scenarios for the region represented whether it is a
national, regional, or local scenario.  In this case, EFED has modeled
the new use on Bermuda grass pasture and hayfields using an existing
turf scenario (FL turf).  The FL turf scenario represents a range of
turf conditions and the Florida scenario is highly vulnerable to runoff.
 Currently, no turf scenarios exist in the major states covered by this
assessment.  Therefore, in order to provide context to this assessment,
EFED has run the proposed new use application rates for the Florida turf
scenario using the weather stations in Austin, Texas (file name
w13958.dvf) and Oklahoma City, Oklahoma (file name w13968.dvf).  The Fl
turf scenario is a standard PRZM scenario developed to provide a
nationally relevant high-end exposure and its use in the local areas
with data from Texas and Oklahoma weather stations is designed to
provide a more regionally relevant exposure estimate.  Results of the
PRZM/EXAMS modeling are presented in Table 5. 

Further description (metadata) and copies of the existing PRZM scenarios
may be found at the following website. 

  HYPERLINK
"http://www.epa.gov/oppefed1/models/water/index.htm#przmexamsshell" 
http://www.epa.gov/oppefed1/models/water/index.htm#przmexamsshell 

 EECs (μg/L or ppb) for the proposed use of nicosulfuron on Bermuda
grass in Texas and Oklahoma for use in the Drinking Water portion of the
Human Health Dietary Assessment.

Use	Scenario	1 in 10 year Peak EEC	1 in 10 year Annual EEC	Annual
Average EEC

Bermuda grass Pasture and Hayfields	FL turf with Austin, Texas Weather
0.52	0.09	0.08

	FL turf with Oklahoma City, Oklahoma Weather	0.53	0.12	0.11

	Average	0.52	0.10	0.10

1 – Drinking Water EEC adjusted for percent cropped area (PCA) using
the default PCA of 87%

The modeling results associated with maximum allowable rate per year for
representative crops from SCI-GROW are presented in Table 6.  Attached
to this memo are copies of the original printouts generated SCI-GROW
runs.       

EECs (μg/L or ppb) in the groundwater for the proposed use of
nicosulfuron on Bermuda grass for use in the Drinking Water portion of
the Human Health Dietary Assessment.

Model for Groundwater	

EEC (ppb)

SCI-GROW	

0.078

 



Appendix 1. PRZM/EXAMS Model Output

stored as TXturf Drinking kg ha.out

Chemical: Nicosulfuron

PRZM environment: FLturfSTD.txt	modified Tueday, 21 February 2006 at
15:38:26

EXAMS environment: ir298.exv	modified Tueday, 26 August 2008 at 06:14:08

Metfile: w13958.dvf	modified Tueday, 26 August 2008 at 06:14:44

Water segment concentrations (ppb)

Year	Peak	96 hr	21 Day	60 Day	90 Day	Yearly

1961	0.5123	0.4986	0.4448	0.384	0.3233	0.09039

1962	0.5136	0.5002	0.4467	0.3476	0.2836	0.07886

1963	0.5175	0.5049	0.4552	0.3745	0.3159	0.08716

1964	0.5027	0.4869	0.4273	0.3473	0.2912	0.08099

1965	1.036	1	0.8692	0.6642	0.556	0.1614

1966	0.514	0.5006	0.4486	0.3643	0.3065	0.08625

1967	0.5008	0.4846	0.423	0.34	0.2776	0.07483

1968	0.5075	0.493	0.4437	0.3607	0.3063	0.08696

1969	0.4959	0.4786	0.4136	0.3327	0.2796	0.07925

1970	0.5154	0.5023	0.4509	0.3641	0.3066	0.08701

1971	0.4923	0.4742	0.4066	0.3225	0.2632	0.07261

1972	0.5011	0.4849	0.4232	0.3355	0.2719	0.07352

1973	0.5118	0.498	0.4443	0.3591	0.2975	0.08354

1974	0.506	0.4909	0.4325	0.3422	0.277	0.07547

1975	0.4954	0.4779	0.4128	0.3312	0.2744	0.07688

1976	0.504	0.4884	0.4281	0.3322	0.2674	0.07362

1977	0.5195	0.5074	0.4589	0.366	0.3024	0.08431

1978	0.5208	0.509	0.4624	0.3803	0.3248	0.09168

1979	0.5208	0.509	0.4621	0.3763	0.3165	0.08937

1980	0.5005	0.4842	0.4223	0.3383	0.2793	0.0776

1981	0.5022	0.4863	0.4255	0.3395	0.2808	0.07764

1982	0.499	0.4823	0.4195	0.3376	0.2775	0.07676

1983	0.5084	0.4939	0.4376	0.3524	0.2952	0.08405

1984	0.5111	0.4971	0.4424	0.3506	0.2867	0.07822

1985	0.5156	0.5027	0.4518	0.366	0.3036	0.0837

1986	0.4943	0.4767	0.4101	0.3225	0.2603	0.0709

1987	0.5015	0.4854	0.4239	0.3363	0.2774	0.07741

1988	0.509	0.4946	0.4386	0.3511	0.2928	0.08206

1989	0.4908	0.4723	0.4043	0.3275	0.2727	0.0759

1990	0.4841	0.4642	0.3911	0.3054	0.2456	0.06705

Sorted results

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

0.032258064516129	1.036	1	0.8692	0.6642	0.556	0.1614

0.0645161290322581	0.5208	0.509	0.4624	0.384	0.3248	0.09168

0.0967741935483871	0.5208	0.509	0.4621	0.3803	0.3233	0.09039

0.129032258064516	0.5195	0.5074	0.4589	0.3763	0.3165	0.08937

0.161290322580645	0.5175	0.5049	0.4552	0.3745	0.3159	0.08716

0.193548387096774	0.5156	0.5027	0.4518	0.366	0.3066	0.08701

0.225806451612903	0.5154	0.5023	0.4509	0.366	0.3065	0.08696

0.258064516129032	0.514	0.5006	0.4486	0.3643	0.3063	0.08625

0.290322580645161	0.5136	0.5002	0.4467	0.3641	0.3036	0.08431

0.32258064516129	0.5123	0.4986	0.4448	0.3607	0.3024	0.08405

0.354838709677419	0.5118	0.498	0.4443	0.3591	0.2975	0.0837

0.387096774193548	0.5111	0.4971	0.4437	0.3524	0.2952	0.08354

0.419354838709677	0.509	0.4946	0.4424	0.3511	0.2928	0.08206

0.451612903225806	0.5084	0.4939	0.4386	0.3506	0.2912	0.08099

0.483870967741936	0.5075	0.493	0.4376	0.3476	0.2867	0.07925

0.516129032258065	0.506	0.4909	0.4325	0.3473	0.2836	0.07886

0.548387096774194	0.504	0.4884	0.4281	0.3422	0.2808	0.07822

0.580645161290323	0.5027	0.4869	0.4273	0.34	0.2796	0.07764

0.612903225806452	0.5022	0.4863	0.4255	0.3395	0.2793	0.0776

0.645161290322581	0.5015	0.4854	0.4239	0.3383	0.2776	0.07741

0.67741935483871	0.5011	0.4849	0.4232	0.3376	0.2775	0.07688

0.709677419354839	0.5008	0.4846	0.423	0.3363	0.2774	0.07676

0.741935483870968	0.5005	0.4842	0.4223	0.3355	0.277	0.0759

0.774193548387097	0.499	0.4823	0.4195	0.3327	0.2744	0.07547

0.806451612903226	0.4959	0.4786	0.4136	0.3322	0.2727	0.07483

0.838709677419355	0.4954	0.4779	0.4128	0.3312	0.2719	0.07362

0.870967741935484	0.4943	0.4767	0.4101	0.3275	0.2674	0.07352

0.903225806451613	0.4923	0.4742	0.4066	0.3225	0.2632	0.07261

0.935483870967742	0.4908	0.4723	0.4043	0.3225	0.2603	0.0709

0.967741935483871	0.4841	0.4642	0.3911	0.3054	0.2456	0.06705

0.1	0.52067	0.50884	0.46178	0.3799	0.32262	0.090288

					Average of yearly averages:	0.0828463333333333

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: TXturf Drinking kg ha

Metfile:	w13958.dvf

PRZM scenario:	FLturfSTD.txt

EXAMS environment file:	ir298.exv

Chemical Name:	Nicosulfuron

Description	Variable Name	Value	Units	Comments

Molecular weight	mwt	410.4	g/mol

Henry's Law Const.	henry		atm-m^3/mol

Vapor Pressure	vapr	1.2e-6	torr

Solubility	sol	12000	mg/L

Kd	Kd		mg/L

Koc	Koc	35	mg/L

Photolysis half-life	kdp	250	days	Half-life

Aerobic Aquatic Metabolism	kbacw	16	days	Halfife

Anaerobic Aquatic Metabolism	kbacs	31.5	days	Halfife

Aerobic Soil Metabolism	asm	31.9	days	Halfife

Hydrolysis:	pH 5	15	days	Half-life

Hydrolysis:	pH 7		days	Half-life

Hydrolysis:	pH 9		days	Half-life

Method:	CAM	2	integer	See PRZM manual

Incorporation Depth:	DEPI	0	cm

Application Rate:	TAPP	0.059	kg/ha

Application Efficiency:	APPEFF	.95	fraction

Spray Drift	DRFT	.16	fraction of application rate applied to pond

Application Date	Date	1-Jan	dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 1	interval	14	days	Set to 0 or delete line for single app.

app. rate 1	apprate	0.039	kg/ha

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)

stored as OKturf Drinking kg ha.out

Chemical: Nicosulfuron

PRZM environment: FLturfSTD.txt	modified Tueday, 21 February 2006 at
15:38:26

EXAMS environment: ir298.exv	modified Tueday, 26 August 2008 at 06:14:08

Metfile: w13968.dvf	modified Tueday, 26 August 2008 at 06:14:48

Water segment concentrations (ppb)

Year	Peak	96 hr	21 Day	60 Day	90 Day	Yearly

1961	0.5313	0.5219	0.4836	0.4008	0.3507	0.1067

1962	0.5334	0.5244	0.4879	0.405	0.3591	0.1095

1963	0.5334	0.5244	0.4881	0.4094	0.3596	0.1054

1964	0.5217	0.51	0.4644	0.3887	0.3454	0.1032

1965	0.5227	0.5113	0.4664	0.3888	0.349	0.1053

1966	0.5329	0.5238	0.4871	0.4079	0.3589	0.1085

1967	0.524	0.5129	0.4691	0.3921	0.3423	0.1013

1968	0.5273	0.517	0.4759	0.3997	0.3554	0.1089

1969	0.5281	0.5178	0.477	0.3962	0.3534	0.1084

1970	0.5334	0.5244	0.4879	0.4055	0.3612	0.1105

1971	0.5401	0.5285	0.4838	0.4483	0.3996	0.1231

1972	0.5301	0.5204	0.4812	0.3998	0.3499	0.1037

1973	0.5307	0.5211	0.4825	0.4031	0.3534	0.1069

1974	0.5316	0.5222	0.4842	0.4013	0.3485	0.1027

1975	0.5234	0.5122	0.4764	0.4065	0.3669	0.1134

1976	0.5273	0.5169	0.4747	0.3831	0.3272	0.09734

1977	0.5334	0.5244	0.4875	0.4003	0.3448	0.1

1978	0.5334	0.5244	0.4884	0.4234	0.3815	0.1165

1979	0.5334	0.5244	0.4884	0.4148	0.3697	0.1119

1980	0.5247	0.5138	0.4772	0.3992	0.3553	0.1073

1981	0.5259	0.5152	0.4727	0.3906	0.3392	0.09888

1982	0.5329	0.5238	0.4873	0.4086	0.3581	0.1065

1983	0.5242	0.5132	0.4835	0.4137	0.3684	0.1144

1984	0.5305	0.5209	0.4817	0.3945	0.3443	0.1045

1985	0.5334	0.5244	0.4882	0.4121	0.3643	0.1079

1986	0.5171	0.5045	0.4552	0.3757	0.3245	0.09521

1987	0.5284	0.5183	0.4775	0.3926	0.341	0.1001

1988	0.5293	0.5194	0.4797	0.4004	0.3559	0.1077

1989	0.5284	0.5153	0.4904	0.4263	0.381	0.1159

1990	0.5337	0.5189	0.4786	0.3887	0.336	0.1

Sorted results

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

0.032258064516129	0.5401	0.5285	0.4904	0.4483	0.3996	0.1231

0.0645161290322581	0.5337	0.5244	0.4884	0.4263	0.3815	0.1165

0.0967741935483871	0.5334	0.5244	0.4884	0.4234	0.381	0.1159

0.129032258064516	0.5334	0.5244	0.4882	0.4148	0.3697	0.1144

0.161290322580645	0.5334	0.5244	0.4881	0.4137	0.3684	0.1134

0.193548387096774	0.5334	0.5244	0.4879	0.4121	0.3669	0.1119

0.225806451612903	0.5334	0.5244	0.4879	0.4094	0.3643	0.1105

0.258064516129032	0.5334	0.5244	0.4875	0.4086	0.3612	0.1095

0.290322580645161	0.5334	0.5238	0.4873	0.4079	0.3596	0.1089

0.32258064516129	0.5329	0.5238	0.4871	0.4065	0.3591	0.1085

0.354838709677419	0.5329	0.5222	0.4842	0.4055	0.3589	0.1084

0.387096774193548	0.5316	0.5219	0.4838	0.405	0.3581	0.1079

0.419354838709677	0.5313	0.5211	0.4836	0.4031	0.3559	0.1077

0.451612903225806	0.5307	0.5209	0.4835	0.4013	0.3554	0.1073

0.483870967741936	0.5305	0.5204	0.4825	0.4008	0.3553	0.1069

0.516129032258065	0.5301	0.5194	0.4817	0.4004	0.3534	0.1067

0.548387096774194	0.5293	0.5189	0.4812	0.4003	0.3534	0.1065

0.580645161290323	0.5284	0.5183	0.4797	0.3998	0.3507	0.1054

0.612903225806452	0.5284	0.5178	0.4786	0.3997	0.3499	0.1053

0.645161290322581	0.5281	0.517	0.4775	0.3992	0.349	0.1045

0.67741935483871	0.5273	0.5169	0.4772	0.3962	0.3485	0.1037

0.709677419354839	0.5273	0.5153	0.477	0.3945	0.3454	0.1032

0.741935483870968	0.5259	0.5152	0.4764	0.3926	0.3448	0.1027

0.774193548387097	0.5247	0.5138	0.4759	0.3921	0.3443	0.1013

0.806451612903226	0.5242	0.5132	0.4747	0.3906	0.3423	0.1001

0.838709677419355	0.524	0.5129	0.4727	0.3888	0.341	0.1

0.870967741935484	0.5234	0.5122	0.4691	0.3887	0.3392	0.1

0.903225806451613	0.5227	0.5113	0.4664	0.3887	0.336	0.09888

0.935483870967742	0.5217	0.51	0.4644	0.3831	0.3272	0.09734

0.967741935483871	0.5171	0.5045	0.4552	0.3757	0.3245	0.09521

0.1	0.5334	0.5244	0.48838	0.42254	0.37987	0.11575

					Average of yearly averages:	0.106721

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: OKturf Drinking kg ha

Metfile:	w13968.dvf

PRZM scenario:	FLturfSTD.txt

EXAMS environment file:	ir298.exv

Chemical Name:	Nicosulfuron

Description	Variable Name	Value	Units	Comments

Molecular weight	mwt	410.4	g/mol

Henry's Law Const.	henry		atm-m^3/mol

Vapor Pressure	vapr	1.2e-6	torr

Solubility	sol	12000	mg/L

Kd	Kd		mg/L

Koc	Koc	35	mg/L

Photolysis half-life	kdp	250	days	Half-life

Aerobic Aquatic Metabolism	kbacw	16	days	Halfife

Anaerobic Aquatic Metabolism	kbacs	31.5	days	Halfife

Aerobic Soil Metabolism	asm	31.9	days	Halfife

Hydrolysis:	pH 5	15	days	Half-life

Hydrolysis:	pH 7		days	Half-life

Hydrolysis:	pH 9		days	Half-life

Method:	CAM	2	integer	See PRZM manual

Incorporation Depth:	DEPI	0	cm

Application Rate:	TAPP	0.059	kg/ha

Application Efficiency:	APPEFF	.95	fraction

Spray Drift	DRFT	.16	fraction of application rate applied to pond

Application Date	Date	1-Jan	dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 1	interval	14	days	Set to 0 or delete line for single app.

app. rate 1	apprate	0.039	kg/ha

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)

Appendix 2.  SCI-GROW run for the use of nicosulfuron on bermudagrass

                           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:Nicosulfuron

 time is 10/13/2009  14:21:52

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

  Application      Number of       Total Use    Koc      Soil Aerobic

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

l

t

{



<

=

G

H

¡

¢

¯



˜

™

›

¡

¾

Ó

ÿ

D

F

H

i

‰

 

 

¡

¢

¯

Ö

ì

ù

@

š

@

@

š

@

h@

š

@

h@

š

@

š

@

@

š

@

@

š

@

h@

š

@

h@

š

@

@

kdå

@

š

@

@

š

@

欀孤

h@

š

@

š

@

@

š

@

„@

`„@

„@

„Àô^„@

\

ô

\

ô

摧㪓(ᨀ-----------

      0.044           2.0           0.088      2.40E+01       31.0

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

 groundwater screening conc (ppb) =   7.83E-02 

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

  

 PRZM and EXAMS are Tier II models used to estimate environmental
exposure concentrations in surface water. A description of these models
and the guidelines for selecting input parameters can be found at

  HYPERLINK "http://www.epa.gov/oppefed1/models/water/" 
http://www.epa.gov/oppefed1/models/water/ 

 PAGE  2