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. 
2

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

Target 

Pests

Single 

Applicatio

n 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 
3

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

40924222
4

 sandy loam 0.16/25.2

 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 
5

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 asin the 

Estimated Environmental Concentration of Nicosulfuron for Use on Pasture in Ecological Risk 
6

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.

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.

Fate Property Value Source

Molecular Weight 410.4 g/mol Product chemistry

Vapor Pressure 1.2 x 10-6torr 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.
7

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/EXAMS1 modeling are presented in Table 5. 

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

following website. 

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

Table 5. PCA adjusted1 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%

 

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

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

http://www.epa.gov/oppefed1/models/water/
8

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. 

Table 6. 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
9

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
10

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)
11

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
12

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)
13

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)

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

 0.044 2.0 0.088 2.40E+01 31.0

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

groundwater screening conc (ppb) = 7.83E-02 

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