Document ID: EPA-HQ-OPP-2014-0230-0010
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2015-05-29T04:00Z

PC Code: 125619
                                                           DP Barcode:  D418674
                                                                PC Code: 125619
                                                           DP Barcode:  D418674
              OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
              OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
 --------------------------------------------------------------------------------

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

--------------------------------------------------------------------------------
MEMORANDUM

DATE:	September 30, 2014

SUBJECT:	Drinking Water Exposure Assessment for the Section 3 New Use of Metconazole on Pea and Bean (Dried Shelled, Subgroup 6C), and Sunflower (Subgroup 20B) 

TO:		Laura Nollen, Risk Manager Reviewer
		Barbara Madden, Minor Use Team Leader
		Marion Johnson, Branch Chief
		Risk Integration Minor Use, and Emergency Response Branch
      Registration Division (7505P)
      
      Erin Malone, Risk Manager Reviewer
      Hope Johnson, Product Manager Team 21
      Cynthia Giles-Parker, Branch Chief
      Fungicide Branch
      Registration Division (7505P)

FROM:	Faruque Khan, Ph.D. Senior Fate Scientist
		Environmental Risk Branch I
		Environmental Fate and Effects Division (7507P)
		
APPROVED
BY:		Sujatha Sankula, Ph.D. Branch Chief
		Meghan Radtke, Ph.D., Acting RAPL
		Environmental Risk Branch I
		Environmental Fate and Effects Division (7507P)

Executive Summary

This memo summarizes the estimated drinking water concentrations (EDWCs) of metconazole (5-[(4-Chlorophenyl) methyl]-2,2-dimethyl-1-(1H-1,2,4-triazol-1-ylmethyl)cyclopentanol]) in surface water and groundwater in support of the proposed Section 3 new uses. The Interregional Research Project Number 4 (IR-4) submitted a tolerance petition for metconazole new uses on pea/bean (dried shelled) and sunflower. Foliar spray applications (aerial and ground boom) are being proposed for the new uses. The IR-4 also revised existing crop groupings by converting stone fruit Group 12 to stone fruit Group 12-12, nut tree Group 12 to nut tree Group 14-12 and the expansion from canola seed to rapeseed Subgroup 20A. Since there are no changes in application rates and methods for the revised crop groupings, previous drinking water assessments (DWAs) fulfill the requirement for refining EDWCs for these crops (stone fruit and nut tree nut   -  USEPA 2007, D340378; canola  -  USEPA 2008, D350276).
Metconazole parent is the only residue of concern considered in the drinking water assessment.  No degradates of metconazole were included based on the recommendation from the Residues of Concern Knowledgebase Subcommittee (ROCKS) of the Health Effects Division (HED) (USEPA, 2008, D348234). 

For surface water, the modeled EDWCs for pea/bean (dried shelled) and sunflower for this assessment did not exceed the previously recommended concentrations of 45.5 ug/L (peak) and 22.8 ug/L (30 year annual average concentration) based on the turf scenario (USEPA 2007, D340378) as well as 38.7 ug/L (annual mean concentration) based on the cranberry scenario (USEPA 2010, D380513). However, the previously estimated EDWCs for cranberry use were based on a 0.87 PCA (Percent Cropped Area) factor. Recently, EFED implemented a revised guidance for PCA (USEPA 2014). Since metconazole can be used in agricultural and non-agricultural settings, a PCA factor of 1.0 was used to revise the previously estimated surface water EDWCs based on cranberry use. Revised peak EDWC of 49.5 ug/L from cranberry use exceeded previously recommended EDWC of 45.5 ug/L for turf use. Therefore, the revised recommended EDWCs are 49.5 ug/L for peak and 43.9 ug/L for annual mean concentrations derived from cranberry scenario. The recommended annual average concentration of 22.8 ug/L has not been revised because the PCA factor of 1.0 remains unchanged for turf. 
This is the first time the PRZM-GW model has been used in estimating metconazole EDWCs for groundwater since the inception of the model in 2012. The highest application rate of 0.60 lbs a.i./A for turf was modeled in estimating metconazole EDWCs for groundwater. Since application rates for proposed uses are lower than turf, no additional modeling for PRZM-GW modeling is warranted at this time. The estimated PRZM-GW groundwater acute concentration of 51.8 ug/L and chronic concentration of 20.0 ug/L are higher than the previously recommended concentration of 0.38 ug/L for turf (USEPA 2007, D340378). Therefore, the current EDWCs supersede the previously recommended EDWCs for groundwater. The revised recommended EDWCs for both surface water and groundwater for use in HED's human health dietary risk assessment are summarized in Table 1. 

Table 1.  Recommended EDWCs for the Proposed Uses of Metconazole for Drinking Water Sources 
Drinking Water Source
Crop Scenario (Model)
                                 Peak Exposure
                                    (Acute)
                                    (ug/L)
                             Annual Mean Exposure 
                             (Non-Cancer Chronic)
                                    (μg/L)
                            30-year Mean Exposure 
                               (Cancer Chronic)
                                   (ug/L) 
Surface Water
Turf  
                                     45.5
                                     31.3
                                    22.8[1]

Cranberry 
                                    49.6[1]
                                43.9[,][1,][2]
                                     NA[3]
Groundwater
WI Central Sand Scenario 
                                 51.8[,1,][4]
                                     NA[3]
                                 20.0[,1,][4]
[1] Bolded values are the recommended EDWCs for surface water and groundwater for metconazole uses
2 The provisional cranberry scenario is applicable for a year simulation only. 
[3] Not applicable [4] PRZM-GW model was used to reassess groundwater EDWCs for turf use, which has the highest the highest application rate of 0.6 lbs a.i/A for metconazole; groundwater EDWCs are based on a PRZM-GW 100 years simulation

Proposed Use
Metconazole is a broad-spectrum systemic triazole fungicide that can be applied as a foliar spray via ground and aerial application methods. The IR-4 and Valent Corporation are seeking registration of two new uses and tolerances for revised crop groups (Table 2). According to the proposed label (Metconazole 50WDG Fungicide), metconazole can be applied at a maximum application rate/year of 0.125-0.44 lb a.i./A via ground and aerial application methods. Two of the proposed uses have not been considered previously in drinking water assessments. These include uses on pea/bean (dried shelled) and sunflower. Since there are no changes in application rates and methods for the revised crop groupings, previous DWAs conducted for various crops including stone fruit and tree nut (USEPA 2007, D340378) and canola (USEPA 2008, D350276) fulfill the requirement for refining EDWCs for these crops.

Table 2. Proposed New Uses and Conversion of Old Crop Groups to New Crop Groups for Metconazole
                                   Use Site
                               Single App. Rate
                                 (lbs a.i./A)
                                   # of App
                               Annual App. Rate
                                 (lbs a.i./A) 
                          Retreatment Interval (days)
                                      PHI
                               Application Type
                                       
                                  EPA Reg # 
                             Comments/restrictions
                              Proposed New Uses 
                   Dried Shelled Pea and bean except soybean
                                 (Subgroup 6C)
                                  0.08-0.125
                                       2
                                     0.25
                                     7-10
                                      21
                            Aerial and Ground boom
                                   59639-147
                                       
                                       
                           Sunflower (Subgroup 20B)
0.078-0.125
                                       2
                                     0.25
                                     7-14
                                      21
                            Aerial and Ground boom
                                   59639-147
                                       
                                       
                             Crop Group Expansion
                       Canola [Rapeseed (Subgroup 20A)]
                                 0.0625-0.125
                                       1
                                     0.125
                                      --
                                      35
                                    Aerial
                                       
                                   59639-147
                           One application per year
                                       
                Conversion of old crop group to new crop group
                          Stone Fruit  (Group 12-12)
                                  0.11-0.125
                                       3
                                     0.375
                                     7-14
                                      14
                                    Aerial
                                   59639-147
                      Maximum two sequential applications
                                   Tree Nut 
                                 (Group 14-12
                                  0.078-0.11
                                       4
                                     0.44 
                                     7-14
                                      25
                                    Aerial
                                       
                                   59639-147
                      Maximum two sequential applications

Residues of Concern

Three degradates were observed at greater than 10% of the applied dose in laboratory fate studies:  M30, hydroxymetconazole, and M13. However, the Residues of Concern Knowledgebase Subcommittee (ROCKS) reported that the residue of concern for metconazole in drinking water is the parent only (USEPA 2008, D348234). Degradates were excluded in the DWA. A detailed rationale for excluding several metconazole metabolites is included in the previous DWA (USEPA 2010, D375778+). 

Modeling Approach and Input Parameters

Models

	Surface Water 

The Surface Water Concentration Calculator (SWCC v 1.106) model was used to generate EDWCs for the Tier II aquatic exposure assessment. The SWCC is a graphical user interface that runs the Pesticide Root Zone Model (PRZM, v 5, November 15, 2006) and the Variable Volume Water Body Model (VVWM, 3/6/2014) (USEPA, 2006b). Simulations are run for multiple (usually 30) years and the EDWCs represent peak values that are expected once every ten years based on the thirty years of daily values generated during the simulation. The default PCA of 1.0 was used for the proposed uses because metconazole can be used in both agricultural and non-agricultural settings (USEPA 2012).

      Groundwater 

The Screening Concentration in Ground Water (SCI-GROW v2.3, Jul. 29, 2003) model[1] is a regression model used as a screening tool to estimate pesticide concentrations found in groundwater that is used for 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.  Ground water concentrations were taken from 90-day average high concentrations from Prospective Ground Water studies. The SCI-GROW model and user's manual may also be downloaded from the EPA Water Models web-page (http://www.epa.gov/oppefed1/models/water/#scigrow). PCAs are not applicable for the SCI-GROW model.

In addition, Tier 1 groundwater EDWCs for metconazole, resulting from its use on turf for the highest  application rate of 0.60 lbs a.i./A for metconazole was also estimated using the PRZM-GW model (USEPA, 2012c), with the GW-GUI (Graphical User Interface, version 1.0, August 31, 2012).  PRZM-GW is a one-dimensional, finite-difference model that estimates the concentrations of pesticides in groundwater.  It accounts for pesticide fate in the crop root zone by simulating pesticide transport and degradation through the soil profile after a pesticide is applied to an agricultural field. PRZM-GW permits the assessment of multiple years of pesticide application (up to 100 years) on a single site. Six standard scenarios, each representing a different region known to be vulnerable to groundwater contamination, are available for use with PRZM-GW for risk assessment purposes. In PRZM-GW simulations, each of these standard scenarios was used.  PRZM-GW output values represent pesticide concentrations in a vulnerable groundwater supply that is located directly beneath a rural agricultural field following many years of pesticide application. Since there is no breakthrough (i.e., the number of days that it takes for the applied chemical to reach the aquifer) observed for 30 years of simulations, extended weather files for 100 years were used to determine EDWCs for modeled scenarios. PCAs are not applicable for the PRZM-GW model.

Input Parameters

A summary of the model input parameter values used in SWCC, SCI-GROW, and PRZM-GW models are in Table 3, Table 4, and Table 5, respectively. Input parameters were selected in accordance with EFED's "Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides," Version 2.1 (USEPA 2009). Sample model output files are located in Appendix B. 

Table 3. SWCC Input Parameters for Metconazole Proposed Uses  
Parameter
Input Value and Unit
 Source
Comment
Scenarios for proposed Uses
Pea and Bean (Crop subgroup 6C)
Sunflower (Crop subgroup 20B)

MIbeanSTD
NDCanolaSTD1

N/A[2]

All available scenarios for each use
Maximum Single 
Application Rate lbs a.i./A
(Number of Application/year)
Pea and Beans: 0.125 (2)
Sunflower: 0.125 (2)

Proposed labels
EPA Reg. No. 59639-147

Label directions
Initial Application Date

Pea and Beans: August 24
Pea and Beans: July 20

Based on crop scenarios and label directions
Application Interval (days)
Pea and Beans: 7
Sunflower: 7
 

Intervals were selected to reflect labeled application patterns.
Application Method
Aerial and Ground Bean/Peas, Sunflower
Proposed labels
Label directions
Hydrolysis (t1/2)
0
MRID 46902201
Stable
Application efficiency and Spray Drift (fraction)
Aerial: 0.95 and 0.135
Ground: 0.99 and 0.066
 Input Guidance[3]

Default
Molecular weight
319.8
MRID 447215-05

Solubility in water 
(pH 7, 20 °C)
18.7 mg/L

Solubility of cis isomer[4]
Vapor pressure
7.8 x10[-][8] Torr  (mmHg) 

Vapor Pressure of Cis-isomer[4]
Hydrolysis (t1/2)
0
MRID 46902201

Stable
Aquatic photolysis (t1/2)
72 days
MRID 46902202
                                      ---
Aerobic soil metabolism (t1/2)
 470.7 days 
MRID 46970901
MRID 46902204
MRID 46808408
Upper 90[th] %-ile confidence bound on the mean of  six DT50s
Aerobic aquatic metabolism (t1/2)
Stable
MRID 46902205

Pond water-sediment system from Germany
Anaerobic aquatic metabolism (t1/2)
Stable
MRID 46808410

Greater than 1 year
Partition coefficient Koc
1544 mL/g 
MRID 46808411

Average of four Koc   
[1] In absence of sunflower standard scenario, NDCanola STD was used as a surrogate
[2] Not Applicable
3 USEPA 2010  http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm
4 Since the cis-isomer is the major constituent (85%) of metconazole, physical properties of the cis-isomer were used in modeling
	

Table 4. SCI-GROW (v2.3) Input Parameter Values for Metconazole
                                   Parameter
                                     Value
                                    Source
                                   Comments
Application Rate (lbs a.i./acre)
                                     0.125
                            EPA Reg. No. 59639-147
                                Proposed label
Number of applications
                                       2
                            EPA Reg. No. 59639-147
                                       
Koc (mL/g)
                                    1213.5
                                 MRID 46808411
                         Median of four Koc values.  
Aerobic soil metabolism t (1/2) (days)
                                     261.7
MRID 46970901
MRID 46902204
                                 MRID 46808408
                            Median of six values.  

Table 5. PRZM-GW Input Parameters[1] for Metconazloe Uses  
                                       
                                 Variable Name
                                       
                                  Data Value
                                  Data Source
                                    MRID(s)
                                    Comment
Application Method
Foliar Application 

EPA Reg. No. 59639-147
                                Proposed label
Application Rate 
(lbs a.i./A) [kg/ha]
0.125 [0.140] (Pea/Bean and Sunflower 0.12 [0.135]
 Turf:: 0.12 [0.134]
EPA Reg. No. 59639-147 
                                       
Application Frequency
Dried bean/peas: 2 time per year 
Sunflower: 2 time per year
Turf: 5 times/year
EPA Reg. No. 59639-

US EPA, 2007
Proposed label

                                 Previous DWA
Application Interval (days)
7 (Pea/Bean)
7 Sunflower: 
14 (Turf)
EPA Reg. No. 59639-147
Proposed label
                                Proposed Label
Hydrolysis, DT50 (Days)
Stable
MRID 46902201
                                      ---
Aerobic Soil Metabolism  DT50 (Days) 
 470.7 days 
MRID 46970901
MRID 46902204
MRID 46808408
      Upper 90[th] %-ile confidence bound on the mean of  six half-lives
Koc (mL/goc)
1544 mL/g 
MRID 46808411

Average of four Koc  
[1]EFED input parameter guidance: http://www.epa.gov/oppefed1/models/water/przm_gw/wqtt_przm_gw_input_guidance.htm

Modeling Results

The estimated metconazole concentrations in surface water used for drinking water are summarized in Table 6. The estimated concentrations in surface water for use on sunflower resulted in the highest EDWCs at 8.25 ug/L for acute, 6.45 ug/L for annual mean and 5.08 ug/L for a 30-year annual average. Acute and chronic estimated metconazole concentrations in surface water used for drinking water ranged from 2.89 to 8.25 ug/L. The estimated metconazole concentrations in groundwater used for drinking water are summarized in Table 7. The estimated concentrations in groundwater for use on turf resulted in the highest EDWCs at 51.8 ug/L for acute and 20.0 ug/L for a 100-year annual average. The PRZM-GW EDWCs are higher than the SCI-GROW EDWCs for the proposed uses and previously recommended EDWC of 0.38 ug/L for turf uses. Therefore, the current EDWCs supersede the previously recommended EDWCs for groundwater.   

Table 6.  EDWCs for Metconazole Applications to Various Crops 
Drinking Water Source
Crop
Crop Scenario
1-in-10-year Peak Exposure 
1-in-10-year Annual Mean Exposure 
                            30-year Mean Exposure 

                             Concentration (ug/L)
Surface water[1]
Bean and Pea (dried Shelled)
MI Bean STD
                                  7.57(A)[2]
                                  6.65(G)[3]
                                    4.45(A)
                                    3.97(G)
                                    3.33(A)
                                    2.89(G)

Sunflower
ND Canola  STD
                                       
                                   8.25 (A)
                                   6.60 (G)
                                       
                                   6.45 (A)
                                   5.04 (G)
                                       
                                   5.08 (A)
                                    3.92(G)
1 Surface Water Concentration Calculator was used to determine EDWCs in surface water
[2] Aerial application
[3] Ground boom application 
Table 7. Results from PRZM-GW and SCI-GROW Modeling Based on Metconazole Uses on Turf and Proposed New Uses
                                       
                                     Crop
                                   Scenario
                                    Highest
                                     Daily
                                 Value (ug/L)
                                Average (ug/L)
                  Average Simulation Breakthrough Time (days)
Turf[1]
(0.12 lbs a.i./A x 5 applications)
FL citrus
                                     29.1
                                     20.2
                                     16195

FL potato
                                     0.04
                                     0.02
                                     34338

GA peanut
                                     6.11
                                      1.8
                                     26738

NC cotton
                                     14.1
                                      9.1
                                     16492

DELMARVA sweet corn
                                     20.0
                                      9.1
                                     19640

WI corn
                                    51.8[2]
                                    20.0[2]
                                     23037
Pea/Bean (Dried Shelled) and Sunflower
(0.125 lbs a.i./A x 2 applications)
Generic Scenario[3]
                                     0.032
                                     0.032
                                     NA[4]
[1] PRZM-GW modeled the highest metconazole application rate of 0.6 lbs a.i/A for metconazole uses
[2] Bolded concentrations are the highest EDWCs determined for groundwater
[3] EDWCs are based on SCI-GROW model 
[4] Not Applicable

Monitoring Data

Monitoring data for metconazole were available from the United States Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program Data Warehouse (http://infotrek.er.usgs.gov/nawqa_queries/jsp/swmaster.jsp), searched on September 08, 2014.  Metconazole was not detected in 75 surface water samples collected from multiple states (CA, GA, IA, IN, MO, NE, TX, and WI) at the limit of quantitation (LOQ) of 5.2 ng/L. However, the study design of NAWQA is not targeted to account for all metconazole use areas, timing of application and other factors which may more accurately represent spatially and temporally dependent variables influencing runoff vulnerability. No groundwater and sediment data are available at this time.

Drinking Water Treatment

There is no available information on the effects of drinking water treatment on metconazole.  The EDWCs in this assessment are representative of concentrations in drinking water source water (pre-treatment). For surface water, the conceptual model assumes that a pesticide reaches surface water via spray drift or surface runoff, it is instantaneously mixed, and concentrations are observed in the water body. Metconazole is stable to hydrolysis. Therefore, metconazole will not degrade by hydrolysis during the time that elapses from drinking water intake through distribution to the first tap. Metconazole is also not sensitive to aqueous photolysis. Therefore, if ultraviolet light were used as a means of disinfection, degradation of metconazole would not be expected to be significant. Metconazole has a low degradation rate in aerobic aquatic environments, therefore, there is not expected to be significant degradation during water treatment. The most successful treatment process for removing pesticides from drinking water is thought to be treatment with granular activated carbon (GAC), which is only used in larger drinking water treatment facilities. The ability of GAC to remove pesticides will vary with the properties of the chemical, the viability of the biofilm on the GAC, and whether the sorption sites on GAC have reached capacity (Badriyha et al., 2003; Zhao et al., 1999). Data on the sorption of metconazole to GAC are not available; however, the average Koc (1544 mL/g) value of metconazole suggests that there is a potential for removal of metconazole through GAC treatment because of its high adsorption coefficient. 

Literature Cited

Badriyha, B. N., Ravindran, V., Den, W., & Pirbazari, M. 2003.  Bioadsorber efficiency, design, and performance forecasting for alachlor removal. Water Research, 37.

USEPA, 2007.  Revised Drinking Water Exposure Assessment for Metconazole Based on The Proposed Labels of BAS 556 01F, Caramba(TM), V-10116 VPP, Metconazole 50 WDG, and Metconazole Technical. Environmental Fate and Effects Division.  Office of Pesticide Programs. United States Environmental Protection Agency (D D340378). 
 
USEPA, 2008. Updated Drinking Water Exposure Assessment for the use of metconazole in/on canola seed. Environmental Fate and Effects Division.  Office of Pesticide Programs. United States Environmental Protection Agency (D D350276).

USEPA. 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version 2.1.  Environmental Fate and Effects Division.  Office of Pesticide Programs. United States Environmental Protection Agency. Available at http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (Accessed February 10, 2013).

USEPA, 2010. Drinking Water Exposure Assessment to Establish Tolerances of Parent Metconazole for Tuberous/Corm (Subgroup IC) and Bushberry (Subgroup 13-07C) crops as well as Seed Treatments. Environmental Fate and Effects Division.  Office of Pesticide Programs. United States Environmental Protection Agency (D375778+).

USEPA. 2014. Guidance on Development and Use of Community Water System Drinking Water IntakePercent Cropped Area Adjustment Factors for Use in Drinking Water Exposure Assessments:2014 Update. Environmental Fate and Effects Division, Office of Chemical Safety and Pollution Prevention, United States Environmental Protection Agency.

Zhao, X., Hickey, R. F., & Voice, T. C. 1999.  Long-term evaluation of adsorption capacity in a biological activated carbon fluidized bed reactor system. Water Research, 33(13).

                           Appendix A: Model Outputs

Model: SWCC

Variable Volume Water Model, SWCC Compatible Version
 
 *******************************************
Performed on:  9/ 9/2014  at  9:33
 
Peak 1-in-10       =   8.25     ppb
Chronic 1-in-10    =   6.45     ppb
Simulation Avg     =   5.08     ppb

YEAR    Peak      4-day      21-day     60-day     90-day   Yearly Avg Benthic Pk  Benthic 21-day
  1    1.26E+00   1.20E+00   9.95E-01   7.73E-01   7.09E-01   2.81E-01   5.22E-01   5.22E-01
  2    1.97E+00   1.90E+00   1.68E+00   1.45E+00   1.36E+00   8.75E-01   1.15E+00   1.15E+00
  3    3.32E+00   3.22E+00   2.91E+00   2.69E+00   2.57E+00   1.75E+00   2.28E+00   2.28E+00
  4    6.15E+00   5.97E+00   5.40E+00   4.81E+00   4.57E+00   3.08E+00   4.09E+00   4.08E+00
  5    5.13E+00   5.05E+00   4.78E+00   4.53E+00   4.48E+00   4.00E+00   4.30E+00   4.30E+00
  6    5.11E+00   5.04E+00   4.83E+00   4.66E+00   4.56E+00   4.08E+00   4.40E+00   4.40E+00
  7    5.33E+00   5.26E+00   5.03E+00   4.78E+00   4.67E+00   4.31E+00   4.56E+00   4.56E+00
  8    6.38E+00   6.27E+00   5.91E+00   5.45E+00   5.26E+00   4.52E+00   5.02E+00   5.02E+00
  9    5.55E+00   5.47E+00   5.24E+00   4.98E+00   4.86E+00   4.56E+00   4.84E+00   4.87E+00
 10    7.04E+00   6.96E+00   6.60E+00   6.11E+00   5.90E+00   5.06E+00   5.61E+00   5.61E+00
 11    1.07E+01   1.04E+01   9.48E+00   8.66E+00   8.29E+00   6.06E+00   7.51E+00   7.51E+00
 12    7.50E+00   7.43E+00   7.21E+00   7.39E+00   7.64E+00   6.63E+00   7.39E+00   7.43E+00
 13    7.24E+00   7.16E+00   6.88E+00   6.63E+00   6.55E+00   6.02E+00   6.40E+00   6.39E+00
 14    6.67E+00   6.60E+00   6.36E+00   6.13E+00   6.18E+00   5.72E+00   6.17E+00   6.21E+00
 15    7.18E+00   7.12E+00   6.90E+00   6.75E+00   6.63E+00   5.96E+00   6.53E+00   6.53E+00
 16    6.82E+00   6.75E+00   6.51E+00   6.40E+00   6.54E+00   5.90E+00   6.42E+00   6.46E+00
 17    7.11E+00   7.02E+00   6.74E+00   6.42E+00   6.27E+00   5.74E+00   6.19E+00   6.18E+00
 18    7.15E+00   7.08E+00   6.86E+00   6.56E+00   6.55E+00   6.05E+00   6.44E+00   6.43E+00
 19    7.29E+00   7.21E+00   6.94E+00   6.65E+00   6.51E+00   6.10E+00   6.43E+00   6.43E+00
 20    7.98E+00   7.84E+00   7.42E+00   7.12E+00   7.02E+00   6.08E+00   6.70E+00   6.69E+00
 21    7.14E+00   7.05E+00   6.77E+00   6.53E+00   6.63E+00   6.01E+00   6.56E+00   6.60E+00
 22    7.72E+00   7.65E+00   7.39E+00   7.04E+00   6.84E+00   5.92E+00   6.57E+00   6.57E+00
 23    7.53E+00   7.44E+00   7.22E+00   6.91E+00   6.79E+00   6.19E+00   6.60E+00   6.59E+00
 24    7.16E+00   7.09E+00   6.85E+00   6.58E+00   6.52E+00   6.21E+00   6.43E+00   6.47E+00
 25    7.37E+00   7.27E+00   6.97E+00   6.67E+00   6.57E+00   6.03E+00   6.37E+00   6.37E+00
 26    6.72E+00   6.64E+00   6.40E+00   6.13E+00   6.20E+00   5.78E+00   6.18E+00   6.22E+00
 27    1.24E+01   1.20E+01   1.08E+01   9.38E+00   8.85E+00   6.43E+00   7.85E+00   7.84E+00
 28    7.74E+00   7.66E+00   7.42E+00   7.48E+00   7.62E+00   6.82E+00   7.59E+00   7.63E+00
*******************************************************************************

Model SCIGROW

                           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:Metconazole
 time is  9/22/2014  15:14:15
 ------------------------------------------------------------------------
  Application      Number of       Total Use    Koc      Soil Aerobic
  rate (lb/acre)  applications   (lb/acre/yr)  (ml/g)   metabolism (days)
 ------------------------------------------------------------------------
      0.125           2.0           0.250      1.21E+03      261.7
 ------------------------------------------------------------------------
 groundwater screening cond (ppb) =   3.17E-02 
 ************************************************************************                           

                                 MODEL PRZM-GW
                                       
Groundwater Analysis for Metconazole and the Wisconsin Corn - WI Central Sands Scenario
Estimated groundwater concentrations and breakthrough times for metconazole are presented in Table 1 for the Wisconsin Corn - WI Central Sands groundwater scenario. A graphical presentation of the daily concentrations in the aquifer is presented in Figure 1. These values were generated with the PRZM-GW (Version 1.07). Critical input values for the model are summarized in Tables 2 and 3.

Table 1. Groundwater Results for Metconazole and the Wisconsin Corn - WI Central Sands Scenario.
Peak Concentration (ppb)
    51.8
Post-Breakthrough Mean Concentration (ppb)
      46
Entire Simulation Mean Concentration (ppb)
      20
Average Breakthrough Time (days)
23037.51
Throughputs
1.569701

Table 2. Chemical Properties for Groundwater Modeling of Metconazole.
Koc (ml/g)
1544
Surface Soil Half Life (days)
470.7
Hydrolysis Half Life (days)
0
Diffusion Coefficint Air (cm2/day)
0.0
Henry's Constant
0.0
Enthalpy (kcal/mol)
0.0

Table 3. Pesticide Application Scheme Used for Metconazole (applied every year of the simulation)
Application Days Relative to Emergence Date (05/01)
Application Method
Application Rate
(kg/ha)
30
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.134
44
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.134
58
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.134
72
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.134
86
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.134

Figure 1. Aquifer Breakthrough Curve for Metconazole and the Wisconsin Corn - WI Central Sands Scenario