### 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 D3 60831 ) 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 S CIGROW 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 0.0 8 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 p ests and relevant application information are summarized in Table 1.

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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

o f the f ate studies were reviewed in1990 (see details in the EFED review “DPR

-V9360 (Sulfony urea 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 s oil 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 o f its two major degradates (py ridine sulfonamide and py rimidne 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 o f the above three chemicals. At the Illinois study s ite (silty c lay loam; soil pH = 6.0; and organic matter = 4.7%), nicosulfuron, py ridine sulfonamide, py

rimidine 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 s ite (sandy

loam; soil pH = 7.8; and organic matter = 4.7%), nicosulfuron, py

ridine sulfonamide, py

rimidine amine were detected in the 0

- 6 inch zone whereas only the parent compound and py ridine sulfonamide were found in the 6

- 12 inch zone . The movement of py

ridine sulfonamide from the surface to the deeper zone was likely d ue 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. B ased on the aerobic soil metabolism studies reviewed (MRIDs 41082262 and 46240901; the first study was reviewed on February 1 9, 1990), it appeared that the degradation rate and the resulting degradate s under aerobic

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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 c onducted 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. Inacidic soil (MRID 41082262), the major degradates were py ridine sulfonamide (87.4% and 92.9% of the applied at 120 and 240 days, respectively, after application) and py rimidine amine (72.8% and 80.7% at the corresponding period). In neutral/alkaline soil (MRID 46240 901) , the major degradates were py ridine 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 phy

totoxic effects even after a 10

-month rotation. This phy totoxic effect could be worsened by s ite soil characteristics (alkaline soils that favor persistence) and/or climatic conditions (colder climates; dry climates) that slow down the degradation of nico sulfuron. Table 2 includes the environmental fate properties for nicosulfuron

. Table 2. Summary

of Fate Properties for Nicosulfuron

. Study Ty pe Half

-Li fe/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 4092422 2 , 46240901 Anaerobic Soil 63 days 41082623
Adsorption Kd /Koc 40924222

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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 (py

ridine radiolabeled) Illinois (lysimeters/bare ground)

- 120 days (py rimidine radiolabeled) California (lysimeters/bare ground)

- 114 days (py

ridine radiolabeled) Californis (lysimeters/bare ground)

- 120 days (py rimidine radiolabeled) 41082604, 43483901

Li sted 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 (py

ridine sulfonamide and py rimidne 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 py

ridine sulfonamide is more mobile than the parent compound whereas py rimidne 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, py

ridine sulfonamide, py

rimidine amine were detected in the 0

- 6 inch zone where as only

py ridine 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, py ridine sulfonamide, py rimidine amine were detected in the 0

- 6 inch zone whereas only the parent compound and py ridine sulfonamide were found in the 6

- 12 inch zone. The movement of py ridine 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 3 5.9 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. Inacidic soil (MRID 41082262), the major degradates were py ridine sulfonamide (87.4% and 92.9% of the applied at 120 and 240 days, respectively, after application) and py rimidine amine (72.8% and 80.7% at the corresponding period). In neutral/alkaline soil (MRID 46240901) , the major degradates were py ridine sulfonamide (18 % of the applied at 120 days after application) and I N

-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. S ince 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

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Assessment. Model inputs were selected consistent with those used in the 2004 drinking water assessment and are summarized in Table 3

. C opy 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 S ource 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 guidance a Aerobic Soil Metabolism Half

-life 31.9 days EFED guidance a Hydrolysis stable EFED guidance a Aerobic Aquatic Metabolism (water column) 16 days EFED guidance a Anaerobic Aquatic Metabolism (benthic) 31.5 days EFED guidance a Koc 35 EFED guidance a Application Efficiency 95 % for aerial 99 % for ground EFED guidance a Spray Drift Fraction 16 % for aerial for DWA 6.4 % for ground for DWA EFED guidance a

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

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Parameter Nicosulfuron Value Organic Carbon Partition Coefficient (KOC

### ) 24.01 Aerobic Soil Metabolism Half

-Li fe 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. I n 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 1 

### 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/w ater/index.htm#przmexamsshell 

### Table 5 . PCA adjusted 1 

### 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/w ater/

### 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/Lor 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

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Appendix 1. PRZM/EXAMS Mo del 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 Tueda y, 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 196 4 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 197 5 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 0.42 23 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 result s 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 0.27 27 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 Dr inking 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 0.39 96 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 0.533 4 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 0.06 45161290322581 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 0.48 71 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 0.6129032 25806452 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 0.51 52 0.4764 0.3926 0.3448 0.1027

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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 0.33 92 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 ye arly 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 Vari able 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 Metaboli sm 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)

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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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