UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
	WASHINGTON, DC 20460

                         OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

		PC Code: 128847
		DP Barcode: 409484 and 409488
                   		Date: November 8, 2013

MEMORANDUM

Subject:	Ecological Risk Assessment for the Proposed New Use of Difenoconazole on Canola and Oilseed Subgroup 20A

To:		Rosemary Kearns, Risk Manager Reviewer
	Tony Kish, Risk Manager
      Registration Division (7505P)

From:	Michael Lowit, Ph.D., Ecologist
            Faruque Khan, Ph.D., Senior Fate Scientist
            Sujatha Sankula, Ph.D., Branch Chief
            Environmental Risk Branch I
            Environmental Fate and Effects Division (7507P)

This memorandum summarizes the ecological risks associated with the proposed new use of the fungicide difenoconazole.  The risk assessment considers use of the product Inspire[(R)] on canola and oilseed subgroup 20A.

Foliar applications (ground or aerial spray and chemigation) are proposed at 0.113 lb ai/A/crop.  It is assumed that there is one crop/year and an annual limit of 0.113 lb ai/A for this use.

The single maximum application rate is similar to previously assessed uses and EECs are lower than those for many previously assessed uses.  However, a risk assessment was conducted to incorporate additional toxicity data that has been reviewed since the last risk assessment (D402993, 8/29/2012).  The recently reviewed difenoconazole studies addressed acute and chronic toxicity to freshwater fish (MRID 48453201 and 48453205), avian acute oral toxicity (MRID 48453202), and terrestrial plant toxicity (MRID 48453203 and 48453204).  The major degradate (1,2,4-triazole and triazole acetic acid) studies addressed acute toxicity to freshwater fish (MRID 48474301 and 48453209) and freshwater invertebrates (MRID 48453206 and 48453208).

As in recent risk assessments, total toxic residue (TTR) EECs were used to characterize risk when guideline data were not available for the major degradates (1,2,4-triazole and triazole acetic acid) and toxicity of the degradates was assumed equal to that of difenoconazole.
1.	Executive Summary

The Environmental Fate and Effects Division (EFED) evaluated the proposed new use of the broad-spectrum fungicide difenoconazole (Inspire[(R)]) on canola and oilseed subgroup 20A. Difenoconazole is a fungicide in the conazole chemical class.  Fungicidal activity of the conazole class is attributed to the inhibition of ergosterol biosynthesis.

A number of risk assessments have been conducted on difenoconazole.  Previous assessments identified risk concerns primarily for aquatic invertebrates, fish, birds, and mammals on a chronic basis (on an acute basis for estuarine/marine invertebrates for certain uses).  In past assessments, a risk concern was not precluded for terrestrial plants due to lack of acceptable data.  Taxonomic groups for which concern levels were exceeded for the proposed use (Table 1) are similar to those identified in previous assessments.

Table 1. Potential Effects to Listed Species Associated with the Proposed New Use of Difenoconazole
                                  Listed Taxa
                               Direct Effects[1]
                               Indirect Effects
          Terrestrial and semi-aquatic plants  -  monocots and dicots
                              Yes (listed dicots)
                                      Yes
                                     Birds
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                         Terrestrial-phase amphibians
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                                   Reptiles
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                                    Mammals
                                 No  -  Acute
                               Yes  -  Chronic
                                      Yes
                                Aquatic plants
                                     No[2]
                                      Yes
                                Freshwater fish
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                           Aquatic-phase amphibians
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                           Freshwater invertebrates
                                 No  -  Acute
                                No  -  Chronic
                                      Yes
                             Estuarine/marine fish
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                        Estuarine/marine invertebrates
                                 No  -  Acute
                                Yes  -  Chronic
                                      Yes
                           Terrestrial invertebrates
                                      No
                                    Yes[3]
[1] RQs for aquatic plants and chronic risk to fish and aquatic invertebrates were based on total toxic residues (TTR) due to a lack of guideline toxicity data for 1,2,4-triazole and triazole acetic acid.  Degradate toxicity was assumed equal to that of difenoconazole for those endpoints.
[2] There is some uncertainty for non-vascular plants because an acceptable study with cyanobacteria is not available; however, there are not currently any listed non-vascular plant species.
[3] Only for obligate relationships with listed terrestrial plant species (dicots).

2.	Data Gaps

Several data gaps remain, as identified in past risk assessments (data unavailable or available data is insufficient).  The impact of these data gaps on the risk conclusions varies with the use and application rate of difenoconazole.

   * 850.1350 (Estuarine-marine invertebrate life-cycle)  -  TGAI, difenoconazole

   * 850.2100 (Acute oral toxicity to birds)  -  CGA-71019 (1,2,4-triazole) and CGA-142856 (triazole acetic acid)

   * 850.4550 (Cyanobacteria toxicity)  -  TGAI, difenoconazole

   * 850.4100 (Terrestrial plant toxicity, seedling emergence)  -  TEP
      - Tier II testing is required or a Tier I test can be used if a NOAEC is established at the maximum labeled single application rate.  See section 8.1.3 for additional issues with available study.

   * 850.4150 (Terrestrial plant toxicity, vegetative vigor)  -  TEP
      - Tier II testing is required or a Tier I test can be used if a NOAEC is established at the maximum labeled single application rate.

   * There is uncertainty associated with chronic risk to benthic invertebrates given that porewater EECs are similar to water column EECs and a lack of acceptable toxicity data for benthic invertebrates.  Although a sediment toxicity study (range finding) determining the effects of difenoconazole on benthic organisms has been submitted and reviewed, the numerous deviations in the study limit its use for quantitative purposes.  Data is recommended given that the chronic LOC (1.0) is exceeded for aquatic invertebrates based on comparison of water column species toxicity data to porewater EECs.

    In addition, a guideline chronic fish study (850.1400) with the major degradates (1,2,4-triazole and triazole acetic acid) would be useful for reducing uncertainty in the risk conclusions.

3.	Uncertainties

   *    The assessment of chronic risk to benthic invertebrates was based on toxicity to water column species due to a lack of data suitable for quantitative risk assessment.  Risk conclusions for the proposed use are the same for benthic invertebrates because the pore water EECs are similar to water column EECs; that is, there is a chronic risk concern for estuarine/marine invertebrates but not a risk concern for freshwater invertebrates.  The risk concern triggered for water column estuarine/marine species is protective of estuarine/marine invertebrate species in general (i.e., there is a risk concern); however, the magnitude of the RQ associated with that concern is uncertain for both water column invertebrates (non-definitive endpoint) and benthic invertebrates (lack of data).  There is more uncertainty in the risk conclusions for freshwater invertebrates given that benthic species may be more sensitive than water column species.

There is some uncertainty about risk to aquatic plants because an acceptable study with blue green algae is not available.  There are not currently any listed non-vascular plants so the uncertainty is for non-listed species.  Blue-green algae would need to be about 33x more sensitive than Navicula pelliculosa to exceed the LOC (non-listed species).

   *    There would not be a chronic risk concern for fish if the degradates are less toxic than difenoconazole (RQ = 0.89 based on a 60-day difenoconazole-only EEC = 0.77 ug/L); therefore, guideline chronic fish studies with the major degradates (1,2,4-triazole  and triazole acetic acid) would be useful for refining the risk conclusions if they demonstrate less toxicity than difenoconazole.

* Before difenoconazole breaks down to 1,2,4-triazole, it forms CGA-205375, (1-[2-Chloro-4-(4-chlorophenoxy)-phenyl]-2-[1,2,4]triazol-1-yl-ethanol).  CGA-205375 has potential to be slightly more mobile in the soil than difenoconazole based on the registrant-submitted adsorption/desorption study.  The potential adverse effect of this degradate on the ecological environment was not addressed in this risk assessment.  If this degradate is shown to have potential ecological or human health concerns, additional fate and transport studies may be requested at a later time.

* Because it is persistent, difenoconazole and its degradates may accumulate in soil after repeated use. This repeated or continuous exposure may result in significant risks to non-target organisms, especially birds and mammals.

   *    This risk assessment only considered the most sensitive of the species evaluated in the registrant-submitted studies. The position of the tested species relative to the distribution of all species' sensitivities to difenoconazole is unknown. Extrapolating the risk conclusions from the most sensitive tested species to non-tested species may either underestimate or overestimate the potential risks to those species.

4.	Summary of Proposed Use

Foliar applications (ground or aerial spray and chemigation) are proposed at 0.113 lb ai/A/crop.  EFED assumes that there is typically one crop of canola per year on a given field; thus, the annual limit for this use is assumed to be 0.113 lb ai/A.
5.	Fate and Transport Summary

Difenoconazole is a fungicide in the conazole chemical class. Fungicidal activity of the conazole class of compounds is attributed to the inhibition of ergosterol biosynthesis. Ergosterol, which controls cell membrane permeability, is a critical component in fungal cell membranes. The mechanism of controlling ergosterol biosynthesis is through the disruption of the fungal cytochrome P-450-mediated 14 α-lanosterol demethylation.  Accumulation of 14 α-methyl sterols correlates with the subsequent loss of ergosterol in the fungal cell wall.

Based on a low vapor pressure of 2.5 x 10[-10] mm Hg and solubility in water of 15 mg/L, difenoconazole has a low propensity to volatilize and generate vapors after application.  At test termination in laboratory studies, the residues detected in an organic volatiles trap totaled 0.7% or less; most instances were less than 0.1% of the applied difenoconazole.  The concentrations of the applied difenoconazole lost through volatilization were not measured in the terrestrial field dissipation studies. Selected physical and chemical properties are presented in Table 2.

Table 2.  Physical and Chemical Properties of Difenoconazole
                                   Property
                                     Value
                                    Source
Common Name
Difenoconazole
MRID 469501-04
CAS Registry No.
119446-68-3

PC Code
128847

Structure

MRID 469501-04
Chemical Name (CAS)

1-{2-[4-(chlorophenoxy)-2-chlorophenyl-(4-methyl -1,3-dioxolan-2-yl)-methyl]} -1H-1,2,4-triazole
MRID 469501-04
SMILES notation
O1CC(C)OC1(Cn2ncnc2)c3c(Cl)cc(Oc4ccc(Cl)cc4)cc3
EPI Suite, v3.12 SMILES
Molecular Formula
C19H17Cl2N3O3
MRID 469501-04
Molecular Weight
406.27
MRID 469501-04
Physical State
Red Liquid

Vapor pressure
2.5 x 10-10 mm Hg (25 [o]C)
MRID 465159-01
Henry's Law constant
8.9 x 10-12  atm x m[3]/mol
MRID 465159-01
Specific Gravity/ Density
1.14g/cm[3] @ 25 [o]C
MRID 469501-04
Solubility in water
15.0 mg/L  @ 25 [o]C
MRID 469501-04
log Kow
4.4 (25 [o]C)
MRID 469501-05

In soil, difenoconazole is persistent and slightly mobile.  Difenoconazole has low potential to reach groundwater, except in soils of high sand and low organic matter content.  During a runoff event, difenoconazole will potentially enter adjacent bodies of surface water.  In an aquatic environment, difenoconazole's main route of dissipation is partitioning into the bottom sediment as shown in an aerobic aquatic metabolism study (MRID 42245134), in which the distribution ratio of sediment and water phases was 8:1 at 1 day post-treatment and 40:1 at 30 days post-treatment. Difenoconazole has the potential to undergo slow to relatively fast aqueous photolysis in clear water.  Table 3 summarizes the environmental fate data of difenoconazole.  Additional environmental fate data, including major degradates and maximum percent formation can be found in a previous assessment (DP377719, 7/20/2010).

Table 3.  Summary of the Environmental Fate Properties of Difenoconazole
                                   Property
                                     Value
                                    Source
Name
Difenoconazole

Henry's Law constant
8.9 x 10-12  atm x m[3]/mol
MRID 465159-01
Soil adsorption coefficient
Koc (L/kg)
3867, 3518, 3471, and 7734
3870, 4587, 4799, and 11202
MRID 422451-35 [A]
MRID 469501-21
Hydrolysis half-life
	pH = 5
	pH = 7
	pH = 9

Stable
Stable
Stable

MRID 422451-27
Photolysis half-life in water
6 days  -  ca. 1 ppm in sterile buffer solution (30-day study)
ca. 9.2 days  -  1mg ai/L in natural water
228 days  -  1.52 ml ai/L in sterile buffer solution (15-day study)
MRID 422451-28

MRID 469501-04
MRID 469501-05[B]
Photolysis half-life in soil
349 - 823 days
MRID 469501-06[C]
Aerobic soil metabolism half-life
84.5 days  -  at 0.1 ppm concentration
1600 days  -  at 10 ppm in loam
1059 days  -  at 10 ppm in sandy loam

120 days  -  at 0.13 ppm; Swiss loam
104 days  -  at 0.13 ppm; Swiss loam
165 (158) days  -  at 0.23 ppm; Swiss sandy loam
204 (187) days   -  at 0.23 ppm; Swiss
sandy loam/loamy sand
204 (198) days  -   at 0.23 ppm; French silty clay loam
433 (408) days  -   at ca. 0.1 ppm in CA loamy sand at 25 [o]C
533 days  -  at ca. 0.1 ppm in CA loamy sand at 25 [o]C
MRID 422451-31
MRID 422451-32[D]
MRID 422451-33[D]

MRID 469501-09
MRID 469501-10
MRID 469501-11

MRID 469501-12

MRID 469501-14
Anaerobic soil metabolism half-life
947 days  -  at 10 ppm in loam

MRID 422451-32

Aerobic aquatic metabolism half-life
860 days (10 mg ai/L)
315 (330) days (nominal 0.1 kg ai/ha =0.17 mg ai/L); Swiss pond water-silty clay loam sediment)
335 (301) days (0.17 mg ai/L; Swiss river water-sandy loam sediment)
565 days (0.04 mg ai/L)
MRID 422451-34 E
MRID 469501-16

MRID 469501-17
Anaerobic aquatic metabolism half-life
1245 days (10mg ai/L)
370 days (433) (0.04 mg ai/L)
MRID 422451-34 E
MRID 469501-19
Terrestrial field dissipation half-life
252 days - determined in the 0- to 3-inch depth  -  CA bare loamy sand
231 days  -  GA bare loamy sand (four applications of 0.13 lb ai/A)
139 days  -  CA bare plot of loam soil (four applications of 0.13 lb ai/A)
462 days  -  ND bare sandy clay loam
MRID 422451-40

MRID 469501-26

MRID 469501-27

MRID 469501-29
Laboratory accumulation in fish
bioaccumulation factor
(Lepomis macrochirus)

a depuration half-life
170x in edible tissues
570x nonedible tissues
330x for whole body

1 day
MRID 422451-42
[A] There was another adsorption/desorption study (MRID 422451-36) reviewed in which  the test soils were autoclaved prior to conducting the study which could distort the mobility characteristic of difenoconazole, thus, the study results were not used for calculation of modeling input parameters.
[B] For modeling purposes, the longest half-life was used as it represents the most conservative scenario.  However, there is considerable uncertainty in the photolysis half-lives because the duration of the studies was considerably shorter than the extrapolated half-life (MRIDs 469501-05 and 469501-06).
C  The soil photolysis half-life under xenon light condition was recalculated to represent the conditions under natural sunlight intensity during 30-day periods between June and September (104.7-246.9 W∙min/cm[2]), as a result, a range of half-lives was obtained.
D  In those aerobic soil metabolism studies (MRID 422451-32 and MRID 422451-33) the test application rate was significantly higher than expected under registrant-proposed use condition for difenoconazole.
[E]  In those aquatic metabolism studies, the test application rates were significantly higher than expected under registrant-proposed use condition for difenoconazole.
6.	Exposure Summary

6.1	Terrestrial Exposure

EECs were calculated based on the maximum single application rate (0.113 lb ai/A).  EECs were calculated in T-REX (v 1.5.2) (Table 4) and TerrPlant (v 1.2.2)[3] (Appendix 1).

Table 4.  Terrestrial Food-Item Residue Estimates for Mammals and Birds for Proposed Foliar Applications of Difenoconazole
                              Size Class
(grams)
                        Dietary and Dose-Based EECs[1]

                                  Short Grass
                                  Tall Grass
                               Broadleaf Plants
                              Fruits/Pods/
Seeds
                                  Arthropods
                                    Mammals
Dose-Based EECs
                                      15
                                     25.86
                                     11.85
                                     14.54
                                     1.62
                                     10.13
                                      35
                                     17.87
                                     8.19
                                     10.05
                                     1.12
                                     6.99
                                     1000
                                     4.14
                                     1.90
                                     2.33
                                     0.26
                                     1.62
Dietary-Based EECs[2]
                                      NA
                                     27.12
                                     12.43
                                     15.26
                                      1.7
                                     10.62
                                     Avian
Dose-Based EECs
                                      20
                                     30.89
                                     14.16
                                     17.37
                                     1.93
                                     12.10
                                      100
                                     17.61
                                     8.07
                                     9.91
                                     1.10
                                     6.90
                                     1000
                                     7.89
                                     3.61
                                     4.44
                                     0.49
                                     3.09
Dietary-Based EECs[2]
                                      NA
                                     27.12
                                     12.43
                                     15.26
                                      1.7
                                     10.62
[1] 0.113 lb ai/A
[2] Size class not used for dietary EECs

6.2	Aquatic Exposure

The Tier II aquatic assessment was performed using PRZM (v3.12.2)/EXAMS (v. <IP_ADDRESS>) modeling with the standard pond scenario. Detailed descriptions of these models can be found in a previous assessment (DP377719, 7/20/2010). Separate EECs were calculated for difenoconazole and its total toxic residues (TTR).  Difenoconazole-only EECs were used to assess risk when data were available that indicated that the major degradates were less toxic than difenoconazole (acute risk to fish and invertebrates).  This approach is different than that used in recent risk assessments (DP377719, 7/20/2010 and DP378927+, 2/22/2011) which calculated TTR EECs for characterization of acute risk to fish and invertebrates due to a lack of toxicity data at that time.  As in those previous assessments, TTR EECs were used to characterize risk when guideline data were not available for the major degradates (aquatic plants and chronic risk to fish and invertebrates).

6.2.1	Exposure Estimates for Difenoconazole

The PRZM/EXAMS input parameters for difenoconazole are shown in Table 5.  Inputs are equivalent to those used in previous assessments (e.g., DP377719, 7/20/2010).  Results of the PRZM/EXAMS modeling are in Table 6. The PRZM/EXAMS outputs are included in Appendix 2.

Table 5.  PRZM/EXAMS Chemical Specific Input Parameters for Difenoconazole
                                   Parameter
                             Input Value and Unit
                                Source/Comments
Scenario
ND Canola STD

Only ND Canola  Scenario is available for this use
Maximum single application rate
Foliar Application

0.113 lbs ai/A (0.127 kg ai/ha)

Inspire Label
(EPA Reg. No. 100-1262),
Method of application
CAM = 2

Foliar Spray

Product Label as above
Maximum number of applications
1(Foliar)

Product Label as above
Application efficiency
0.99 (Ground Spray)
0.95 (Aerial Spray)

No chemigation scenario was modeled but assumed similar to ground application.

EFED Model Input Guidance, Version 2.1 (2009b) a
Spray drift
0.01 (Ground Spray)
0.05 (Aerial Spray)

EFED Model Input Guidance, Version 2.1 (2009b)
Application date and minimum interval between applications (days)
July 18[th]
---
Henry's Law constant
8.9 x 10-12  atm x m[3]/mol
MRID 46515901
Hydrolysis
Stable
MRID 42245127
Aerobic soil metabolism (t1/2)[b]
313 days
MRIDs: 42245131, 46950109-12, and 46950114
Aerobic aquatic metabolism (t1/2) [c]
556 days
MRIDs: 46950116 & 46950117
Anaerobic aquatic metabolism (t1/2) [d]
1110 days
MRID 46950119
Aquatic photolysis t1/2 (days) [e]
Stable
MRID 46950105
Vapor pressure
2.5 x 10-10 mm Hg (25 [o]C)
MRID 46515901
Solubility in water
15 mg/L (25 [o]C)
MRID 46515901
Molecular Weight
406.27
MRID 46950104
Partition coefficient Koc
5381 mL/g
MRIDs: 42245135 and 46950121
[a] Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides (Version 2.1; Oct. 22, 2009)
[b] The 90% of the UCL of the mean metabolism half-life.
[c] The 90% of the UCL of the mean metabolism half-life of all available half-lives but those obtained for high test rate.
[d] At proposed application rate only one half-life was available, the half-life was multiplied by three (i.e., 3 x 370 days).
[e] Estimated half-life is beyond the duration of study, thus considered stable.

Table 6.  Estimated Environmental Concentrations (EECs) of Difenoconazole for Surface Water Based on Selected Crop Scenarios
                             Water Source (model)
                                      Use
                                   Scenario
                              (rate and interval)
                              Application Method
                               Peak EEC (ug/L)
                                    21-Day
                                  EEC (ug/L)
                                    60-Day
                                      EEC
                                    (ug/L)
Concentrations (EECs) of Difenoconazole only
Surface Water (PRZM/EXAMS)

ND Canola STD
(1 application  @ 0.113 lb ai/A)
                                    Aerial
                                     1.00
                                     0.83
                                     0.77

                                    Ground
                                     0.57
                                     0.49
                                     0.45
Concentrations (EECs) of Total Toxic Residues (Difenoconazole and Its Degradates)
Surface Water (GENEEC)

ND Canola STD
(1 application @ 0.113 lb ai/A)
                                    Aerial
                                     3.03
                                     2.95
                                     2.80

                                    Ground
                                     2.74
                                     2.67
                                     2.53

6.2.2	Exposure Estimates for the Total Toxic Residues of Difenoconazole

Difenoconazole and its major degradates (1,2,4-triazole and its conjugates triazole alanine and triazole acetic acid), are assumed to be persistent in the environment with a low soil partition coefficient in all modeled media.  In general, for persistent chemicals, yearly EECs of PRZM/EXAMS are not independent and are correlated to the previous year's concentration in PRZM/EXAMS output.  Therefore, the GENEEC model was used to estimate EECs for TTR (difenoconazole + 1,2,4-triazole + triazole acetic acid) to characterize potential effects on aquatic organisms.  For the TTR GENEEC modeling, all input parameters were the same as listed in Table 5 with the exception of the photolysis half-life, the aerobic soil metabolism half-life, and the aerobic and anaerobic aquatic metabolism half-lives which were assumed to be zero (stable).  A soil partition coefficient (Koc) of 1000 mg/L was also assumed for the total toxic residues.  The TTR EECs for the proposed canola use are listed in Table 6. The GENEEC output file is located in Appendix 2.

6.2.3	Monitoring Data

The U.S. Geological Survey's National Water Quality Assessment program (NAWQA) has conducted some monitoring for difenoconazole.  Twelve surface water and sediment samples collected in California and Georgia were analyzed for difenoconazole.  Difenoconazole was detected in only one of twelve surface water samples; the reported maximum concentration (18.2 ng/L) was detected in California.  Difenoconazole was not detected in sediment samples (limit of quantitation (LOQ) was 0.6 ug/kg-sediment).  NAQWA monitoring data were not targeted specifically to difenoconazole use areas or during times of known difenoconazole use; thus, the dataset may not reflect peak difenoconazole concentrations that may occur in surface waters when runoff events occur shortly after difenoconazole is applied.

Monitoring data for surface water, groundwater, and sediment from the California Department of Pesticide Regulation (CDPR) were searched on October 23, 2013.  Difenoconazole monitoring data were not available.
7.	Ecological Effects Summary

Toxicity data are summarized in Tables 7, 8, 9, and 10 (for details see D377719, 7/20/2010).  Additional toxicity data has been reviewed since the last risk assessment (D402993, 8/29/2012), is briefly summarized below, and is incorporated into the summary tables below as applicable.  The recently reviewed difenoconazole studies addressed acute and chronic toxicity to freshwater fish (MRID 48453201 and 48453205), avian acute oral toxicity (MRID 48453202), and terrestrial plant toxicity (MRID 48453203 and 48453204).  The 1,2,4-triazole studies addressed acute toxicity to freshwater fish (MRID 48474301) and freshwater invertebrates (MRID 48453206).  The triazole acetic acid studies addressed acute toxicity to freshwater fish (MRID 48453209) and freshwater invertebrates (MRID 48453208).  The available studies with 1,2,4-triazole and triazole acetic acid indicate that they are less acutely toxic than difenoconazole to freshwater fish and invertebrates.

The acute oral toxicity of difenoconazole to canary study (MRID 48453202) was a limit test resulting in an LD50 > 2000 mg ai/kg bw.  A single mortality was observed at the treatment rate; however, it was unclear if the death was treatment related or due solely to the observed abnormal heart function in that bird.  No other effects were noted.  The study is acceptable.
The 96-hr LC50 for fathead minnow was 1.8 mg ai/L (MRID 48453201).  Sublethal effects (lethargy, loss of equilibrium, lying on the bottom, and floating at the surface) were observed at treatment concentrations 1.3 mg ai/L and higher.   The observed NOAEC was 0.66 mg ai/L.  The study is acceptable.

The freshwater fish (fathead minnow) life cycle study (MRID 48453205) resulted in a NOAEC = 1.9 ug ai/L.  The LOAEC was 3.7 ug ai/L based on reduced male length of the F0-generation 12 weeks post-hatch.  Additional endpoints were effected at higher test concentrations: F0 generation length at 4 weeks, 8 weeks, and 12 weeks (female); F0 generation weight at 12 weeks (male and female); and F1 generation length at 8 weeks. This study is acceptable.

An acute-to-chronic ratio (ACR) of fathead minnow toxicity data (MRID 48453201 and 48453205) was used to estimate chronic toxicity to rainbow trout because rainbow trout was the most sensitive species on an acute basis.  Likewise, an ACR was used with fathead minnow data (acute and chronic) and sheepshead minnow data (acute) to estimate chronic toxicity to marine/estuarine fish.

The recently submitted terrestrial plant studies (MRID 48453203 and 48453204) showed no statistically significant effects at the limit test concentration (0.111/0.112 lb ai/A for seedling emergence and 0.123 lb ai/A for vegetative vigor).  However, in the seedling emergence study, the lack of statistical significance for three of the dicots (lettuce, soybean, and sugar beet) may have been due to high experimental variability and the magnitude of some of the effects is considered potentially biologically significant.  Lettuce showed reduced emergence (21%), survival (17%), shoot length (26%), and dry weight (24%).  Soybean showed reduced shoot length (23%).  Sugar beet showed reduced survival (18%). Additionally, there was poor emergence (63%) of the sugar beet control seeds; seedlings did not meet the minimum acceptable USDA control germination standard for this species (70%).  These studies are supplemental because the limit test concentration is below the maximum labeled single rate (currently 0.26 lb ai/A, golf course turf).

Table 7.  Summary of Most Sensitive Aquatic Toxicity Endpoints for Difenoconazole
                                 Type of Study
                                    Species
                                Toxicity Value
                                  (ug ai/L)
                                     MRID
Acute  -  Freshwater Fish
Rainbow trout
(Oncorhynchus mykiss)
96-hr LC50 = 810

                                   42245107
Chronic  -  Freshwater Fish
Fathead minnow
(Pimephales promelas)
NOAEC = 1.9
LOAEC = 3.7 based on reduced male length of F0-generation 12 weeks post-hatch
                                   48453205

Rainbow trout
(Oncorhynchus mykiss)
NOAEC = 0.86

Value used for risk assessment.  Based on acute-to-chronic ratio of fathead minnow data to rainbow trout data (the most acutely sensitive species).[1]
                                       -
Acute  -  Freshwater Invertebrate
Water flea
(Daphnia magna)
48-hr EC50 = 770
                                   42245110
Chronic  -  Freshwater Invertebrate
Water flea
(Daphnia magna)
NOAEC = 5.6
LOAEC = 13.0 based on reduced number of young/adult/reproductive day and adult length
                                   42245114
Chronic  -  Freshwater Invertebrate (Sediment)
Midge
(Chironomus riparius)
EC50 >50 mg ai/kg-sediment (nominal)
NOAEC = 5 mg ai/kg-sediment (nominal)  based on emergence rate & development rate
                                   47648601
Acute  -  Estuarine/Marine Fish
Sheepshead minnow (Cyprinodon variegates)
96-hr LC50 = 819
                                   42245112
Chronic  -  Estuarine/Marine Fish
Sheepshead minnow (Cyprinodon variegates)
NOAEC = 0.86

Based on acute-to-chronic ratio of fathead minnow data to sheepshead minnow data.[1]
                                       -
Acute  -  Estuarine/Marine Mollusk
Eastern oyster
(Crassostrea virginica)
96-hr EC50 = 424
                                   42906701
Acute  -  Estuarine/Marine Invertebrate
Mysid shrimp
(Americamysis bahia)
96-hr LC50 = 150
                                   42245111
Chronic  -  Estuarine/Marine Invertebrate
Mysid shrimp
(Americamysis bahia)
NOAEC < 0.115
LOAEC = 0.115 based on reduced number of young/adult/reproductive day
                                   46950133
Vascular Plant  -  Freshwater
Duckweed
(Lemna gibba)
EC50 = 1900
EC05 = 110
NOAEC < 110
LOAEC <= 100 based on reduced frond number
                                   46920504
Non-vascular Plant  -  Freshwater
Diatom
(Navicula pelliculosa)
EC50 = 98
NOAEC = 53
LOAEC = 150 based on reduced cell density
                                   46920508
[1] Acute toxicity to fathead minnow: LC50 = 1800 ug ai/L (MRID 48453201)

Table 8.  Summary of Most Sensitive Terrestrial Toxicity Endpoints for Difenoconazole
                                 Type of Study
                                    Species
                                Toxicity Value
                                     MRID
Acute  -  Avian Oral Dose
Canary
(Serinus canaria)
LD50 > 2000 mg ai/kg-bw
                                   48453202
Acute  -  Avian Dietary
Bobwhite quail
(Colinus virginianus)
LC50 = 4579 mg ai/kg-diet
                                   42245103
Chronic  -  Avian Dietary
Bobwhite quail
(Colinus virginianus)
NOAEC = 21.9 mg ai/kg-diet
LOAEC = 108 mg ai/kg-diet based on reduction in hatchling body weight
                                   46950202
Acute  -  Mammalian Oral Dose
Laboratory rat
(Rattus norvegicus)
LD50 = 1453 mg ai/kg-bw
                                   42090006
Two Generation Reproduction  -  Mammalian
Laboratory rat
(Rattus norvegicus)
NOAEC = 25 mg ai/kg-diet
LOAEC = 250 mg ai/kg-diet
                                   42090018
Acute  -  Contact
Honey bee
(Apis mellifera)
LD50 >100 ug ai/bee
                                   42245124
Acute  -  Contact
Earthworm
LC50 > 610 mg ai/kg-dw
                                   42245125
Terrestrial Plants
Corn, Onion, Ryegrass, Wheat, Radish, Cabbage, Lettuce, Sugar beet, Soybean, and Tomato
Seedling Emergence
EC25 > 0.111/0.112 lb ai/A[1]
NOAEC >= 0.111/0.112 lb ai/A[1][,2]

Vegetative Vigor
EC25 > 0.123 lb ai/A
NOAEC >= 0.123 lb ai/A
                                   48453203
                                   48453204
[1] Some species were exposed to 0.111 lb ai/A and others were exposed to 0.112 lb ai/A.
[2] Effects at 0.11 lb ai/A on lettuce, sugar beet, and soybean were considered biologically significant.  Lettuce showed reduced emergence (21%), survival (17%), shoot length (26%), and dry weight (24%).  Soybean showed reduced shoot length (23%).  Sugar beet showed reduced survival (18%).

1,2,4-triazole

The recently reviewed studies with 1,2,4-triazole indicate that it is less acutely toxic than difenoconazole to freshwater fish and invertebrates.  Both studies are acceptable.  The 96-hr LC50 = 498 mg ai/L for rainbow trout (MRID 48474301).  Sublethal effects (swimming behavior, loss of equilibrium, respiratory function, and pigmentation) were observed in treatment groups >= 132 mg ai/L.  The 48-hr EC50 > 98.1 mg ai/L for daphnia (MRID 48453206); no mortality or sublethal effects were reported.

A supplemental study (MRID 45880405) evaluated the effects of 1,2,4-triazole on the growth of juvenile rainbow trout (Oncorhynchus mykiss). This 28-day study yielded an LC50 > 100 mg/L.  Growth was not affected at concentrations up to 100 mg/L.  However, significant sublethal effects were observed; from day 23 to day 28, three to five fish were observed to be inactive or have abnormally low activity, to have labored respiration, and to be lying inactive at the bottom of the aquarium in each of the 10, 32, and 100 mg/L test concentrations. The NOAEC for these sublethal effects was 3.2 mg/L.  The data are not comparable to early life stage (ELS) studies submitted on difenoconazole.  ELS studies are designed to examine effects such as hatching success and larval survival in addition to growth of early life stages.  ELS studies may or may not show greater toxicity than juvenile growth studies.

A registrant submitted data summary (MRID 45342701) presented data from several submitted studies including data on birds (MRID 45284015), earthworms (MRID 45297201), daphnids (MRID 00133381), fish (MRID 45284017), and algae (MRID 00133382).  The data suggest that 1,2,4-triazole may be less toxic than difenoconazole to fish, daphnids, and aquatic plants, but more toxic to earthworms.  However, these studies were typically non-GLP compliant studies or journal articles and are not considered to be reliable to make definitive conclusions regarding the toxicity of 1,2,4-triazole.  In some cases, the available study reports are not legible or the study designs were markedly different than guideline protocols such that they provided little useful information.  Therefore, these data are not used in the risk assessment.

Ecological Structure Activity Relationship (ECOSAR) methods were used to predict 1,2,4-triazole toxicity to aquatic non-vascular plants and chronic toxicity to fish and invertebrates based on its structural similarity to chemicals for which aquatic toxicity data are known. A comparison of 1,2,4-triazole ECOSAR estimates to experimentally derived difenoconazole toxicity endpoints suggests that 1,2,4-triazole is not more toxic than difenoconazole to aquatic non-vascular plants, fish (chronic basis), or aquatic freshwater invertebrates (chronic basis).  There is a reasonable confidence in the ECOSAR estimates (at least for fish) given that the ECOSAR estimate of acute toxicity to fish is similar to toxicity observed in available studies.

Table 9.  Summary of Most Sensitive Aquatic Toxicity Endpoints for 1,2,4-Triazole
                                 Type of Study
                                    Species
                                Toxicity Value
                                  (ug ai/L)
                                     MRID
Acute  -  Freshwater Fish
Rainbow trout
(Oncorhynchus mykiss)
96-hr LC50 = 498,000

                                   48474301
Acute  -  Freshwater Invertebrate
Water flea
(Daphnia magna)
48-hr EC50 > 98,100
                                   48453206

Triazole Acetic Acid

The recently reviewed studies with triazole acetic acid indicate that it is less acutely toxic than difenoconazole to freshwater fish and invertebrates.  Both studies are acceptable.  The 96-hr LC50 > 101 mg ai/L for rainbow trout (MRID 48453209); no mortality or sublethal effects were reported.  The 48-hr EC50 > 108 mg ai/L for daphnia (MRID 48453208); no mortality or sublethal effects were reported.

A comparison of triazole acetic acid ECOSAR estimates to experimentally derived difenoconazole toxicity endpoints suggests that triazole acetic acid is not more toxic than difenoconazole to aquatic non-vascular plants, fish (chronic basis), or aquatic freshwater invertebrates (chronic basis).  There is no basis for judging confidence in the ECOSAR estimates because the ECOSAR estimates for acute toxicity to fish and invertebrates are substantially greater (less toxic) than the non-definitive endpoints observed in the available acute toxicity studies.

Table 10.  Summary of Most Sensitive Aquatic Toxicity Endpoints for Triazole Acetic Acid
                                 Type of Study
                                    Species
                                Toxicity Value
                                  (ug ai/L)
                                     MRID
Acute  -  Freshwater Fish
Rainbow trout
(Oncorhynchus mykiss)
96-hr LC50 > 101,000

                                   48453209
Acute  -  Freshwater Invertebrate
Water flea
(Daphnia magna)
48-hr EC50 > 108,000
                                   48453208
7.1	Incidents

Reviews were conducted of the Ecological Incident Information System (EIIS, version 2.1.1), the Agency's Aggregated Incidents Reports database, and the Avian Incident Monitoring System (AIMS) on October 28, 2013.  No incidents were reported in EIIS or AIMS.  Ten minor plant damage incidents were reported for one difenoconazole product (Revus Top) in the aggregated incident database.  The Revus Top label indicates that it is a dual ai product containing mandipropamid as well as difenoconazole.  No incidents were reported for the proposed product (Inspire[(R)]) which does not contain mandipropamid.

8.	Ecological Risks Summary

8.1	Potential Risks of Difenoconazole Exposure to Terrestrial Organisms

The calculated EECs account for 1,2,4-triazole and triazole acetic acid because the proposed use is for a single application.  If the degradates are substantially more toxic than difenoconazole then this risk assessment could underestimate potential risks.

8.1.1	Birds

There is not an acute risk concern for birds from the proposed use.  The acute listed LOC (0.1) was not exceeded on an acute dietary basis (RQs < 0.01).  Acute dose-based RQs were not calculated because the available studies resulted in non-definitive endpoints.  However, a conservative comparison can be made between the EEC and the highest concentration tested in the toxicity studies.  EECs are less than 1/10[th] of the highest dose tested in these studies (i.e., size-class adjusted LD50); therefore acute dose-based risk is expected to be low from the proposed use.

The chronic LOC (1.0) was exceeded for birds consuming short grass (RQ = 1.24) but not any other food items (Table 11).  The chronic risk concern assumes that birds consume 100% of their diet as short grass.  There is a chronic risk concern for birds (listed and non-listed species) from the proposed use.

Table 11. Summary of Avian Acute and Chronic Risk Quotients for Proposed Difenoconazole Foliar Spray Applications
                               Feeding Category
                            Acute Dietary-based RQs
                           Chronic Dietary-based RQs
Short grass
                                   <0.01
                                     1.24
Tall grass
                                   <0.01
                                     0.57
Broadleaf plants/small insects
                                   <0.01
                                     0.70
Fruits/pods/seeds/large insects
                                   <0.01
                                     0.08
Arthropods
                                   <0.01
                                     0.49
BOLD exceeds chronic LOC (1.0).

8.1.2	Mammals

There is not an acute risk concern for mammals from the proposed use (RQs < 0.01).  The chronic LOC (1.0) was exceeded for all mammal size-classes consuming short grass, tall grass, broadleaf plants/small insects, and arthropods (Table 12).  Chronic dietary-based RQs exceed the LOC for mammals consuming short grass.  There is a chronic risk concern for mammals (listed and non-listed species) from the proposed use.

Table 12. Summary of Mammalian Acute and Chronic Risk Quotients for Proposed Difenoconazole Foliar Spray Applications
                             Risk Quotients Based
                                   on Kenaga
                                Upper Bound EEC
                                Dose-Based RQs
                           Chronic Dietary-Based RQs

                                     15 g
                                     35 g
                                    1000 g

                                     Acute
                                    Chronic
                                     Acute
                                    Chronic
                                     Acute
                                    Chronic

Short grass
                                   <0.01
                                     9.41
                                   <0.01
                                     8.04
                                   <0.01
                                     4.31
                                     1.08
Tall grass
                                   <0.01
                                     4.31
                                   <0.01
                                     3.68
                                   <0.01
                                     1.98
                                     0.50
Broadleaf plants/small insects
                                   <0.01
                                     5.29
                                   <0.01
                                     4.52
                                   <0.01
                                     2.42
                                     0.61
Fruits/pods/seeds/lg insects
                                   <0.01
                                     0.59
                                   <0.01
                                     0.50
                                   <0.01
                                     0.27
                                     0.07
Arthropods
                                   <0.01
                                     3.69
                                   <0.01
                                     3.15
                                   <0.01
                                     1.69
                                     0.42
  BOLD exceeds chronic LOC (1.0).

8.1.3	Terrestrial Plants

The LOC (1.0) was not exceeded for monocots (non-listed or listed species) located in dry or semi-aquatic locations (RQs < 0.1) or from spray drift (RQs = 0.25).  There is uncertainty regarding the toxicity to dicots even though no statistical significance was detected in the seedling emergence study.  The lack of statistical significance for three of the dicots (lettuce, soybean, and sugar beet) may have been due to the high experimental variability and the magnitude of some of the effects is considered potentially biologically significant.  Lettuce showed reduced emergence (21%), survival (17%), shoot length (26%), and dry weight (24%).  Soybean showed reduced shoot length (23%).  Sugar beet showed reduced survival (18%). There is not a risk concern for non-listed dicots assuming that the EC25 = 0.111/0.112 lb ai/A (the test concentration); this may be a reasonable assumption given that the maximum observed effect was 26%.  Risk to listed dicot species cannot be precluded given the magnitude of the observed inhibition at 0.111 lb ai/A for lettuce, soybean, and sugar beet.  The NOAEC would need to be about four times lower than 0.111 lb ai/A for a risk concern to semi-aquatic listed dicots.  Tier II testing of lettuce, soybean, and sugar beet would reduce uncertainty for listed dicot species. At this time, a risk concern cannot be precluded for listed dicots.  There is not a risk concern for monocots from the proposed use.

8.1.4	Terrestrial Invertebrates

There is not an acute contact risk concern for bees from the proposed use.  The acute contact-based RQ was not calculated because the available study resulted in a non-definitive endpoint.  However, a conservative comparison can be made between the EEC and the highest concentration tested in the toxicity study.  The EEC (0.3051 ug ai/bee) is less than 1/2.5 of the non-definitive LD50 (>100 ug ai/bee).

Acute contact testing of difenoconazole on earthworms resulted in an LC50 greater than 610 mg ai/kg-dw of substrate, as survival was >95% in all treatment groups. No significant differences were detected in any treatment groups relative to the negative control for survival or weight change. The NOAEC and LOAEC were 610 and > 610 mg ai/kg-dw of substrate based on survival and weight change.  A previous assessment presented an EEC in soil of 0.28 mg/kg-dry soil for use on ornamentals (0.56 lb ai/A/season) which is over three orders of magnitude below the earthworm NOAEC; therefore, there was not a risk concern (see previous assessment for calculations; DP333319, 7/12/ 2007).  There is no risk concern for earthworms from the proposed use given that the proposed application rate is lower than the seasonal application rate for ornamentals.

8.2	Potential Risks of Difenoconazole Exposure to Aquatic Organisms

Assessment of acute risk to fish and invertebrates was based on difenoconazole EECs because available data indicate that 1,2,4-triazole and triazole acetic acid are less acutely toxic than difenoconazole.

TTR (difenoconazole + 1,2,4-triazole + triazole acetic acid) EECs were calculated for other endpoints due to a lack of guideline toxicity data.  This risk assessment may over or underestimate potential risk given the lack of toxicity data.  1,2,4-triazole and triazole acetic acid are assumed equal in toxicity to difenoconazole in the absence of data.

8.2.1	Fish

There is not an acute risk concern for fish from the proposed use.  The acute listed-species LOC (0.05) was not exceeded for freshwater or estuarine/marine fish (RQs < 0.01).

The chronic LOC (1.0) was exceeded for freshwater and estuarine/marine fish (RQ = 3.25).  Given the lack of guideline toxicity data for the major degradates, a chronic risk concern for fish cannot be precluded for the proposed use.

ECOSAR estimates suggest that both degradates are not more toxic than difenoconazole and are potentially less toxic.  There would not be a chronic risk concern for fish if the degradates are less toxic than difenoconazole (RQ = 0.89 based on a 60-day difenoconazole-only EEC = 0.77 ug/L); therefore, guideline chronic fish studies with the major degradates (1,2,4-triazole and triazole acetic acid) would be useful for refining the risk conclusions if they demonstrate less toxicity than difenoconazole.

Table 13. Acute Risk Quotients for Freshwater and Estuarine/Marine Fish Exposed from the Proposed Difenoconazole Use (Difenoconazole EEC)
                                     Peak
                                      EEC
                                    (ug/L)
                                  Freshwater
                                   Acute RQ
                              (LC50 = 810 ug/L)
                               Estuarine/Marine
                                   Acute RQ
                              (LC50 = 819 ug/L)
                                       1
                                   < 0.01
                                   < 0.01

Table 14. Chronic Risk Quotients for Freshwater and Estuarine/Marine Fish Exposed from the Proposed Difenoconazole Use (TTR EEC)
                                  60-day EEC
                                    (ug/L)
                  Freshwater and Estuarine/Marine Chronic RQ
                             (NOAEC = 0.86 ug/L)
                                      2.8
                                     3.25
  BOLD exceeds chronic LOC (1.0).
8.2.2	Aquatic Invertebrates

There is not an acute risk concern for aquatic invertebrates from the proposed use.  The acute listed-species LOC (0.05) was not exceeded for freshwater or estuarine/marine aquatic invertebrates (RQs < 0.01).

The chronic LOC (1.0) was not exceeded for freshwater invertebrates (RQ = 0.52); however, the LOC was exceeded for estuarine/marine invertebrates (RQ > 25.6).  There is a chronic risk concern for aquatic invertebrates (listed and non-listed estuarine/marine species) from the proposed use.
Risk to benthic invertebrates was considered given the fate properties of difenoconazole.   Risk was not assessed using the submitted chronic toxicity range-finding study (MRID 47648601) due to problems with the study design.  Instead, risk to benthic invertebrates was considered using water column invertebrate data (Daphnia and Americamysis) as surrogates.  Pore water difenoconazole concentrations were determined using PRZM/EXAMS (see Appendix 2) and are similar to water column concentrations.  Given the similar EECs, risk conclusions for benthic invertebrates are the same as those for water column invertebrates; that is, there is a risk concern for benthic estuarine/marine invertebrates but not a risk concern for benthic freshwater invertebrates.  The risk concern triggered for water column estuarine/marine species (Table 16) is protective of estuarine/marine invertebrate species in general (i.e., there is a risk concern); however, the magnitude of the RQ associated with that concern is uncertain for both water column invertebrates (non-definitive endpoint) and benthic invertebrates (lack of data).  There is more uncertainty in the risk conclusions for freshwater invertebrates given that benthic species may be more sensitive than water column species.

Table 15.  Acute Risk Quotients for Freshwater and Estuarine/Marine Invertebrates Exposed from the Proposed Difenoconazole Use (Difenoconazole EEC)
                                     Peak
                                      EEC
                                    (ug/L)
                                  Freshwater
                                   Acute RQ
                              (LC50 = 770 ug/L)
                                  Estuarine/
                                Marine Acute RQ
                              (LC50 = 150 ug/L)
                                       1
                                   < 0.01
                                   < 0.01

Table 16.  Chronic Risk Quotients for Freshwater and Estuarine/Marine Invertebrates Exposed from the Proposed Difenoconazole Use (TTR EEC)
                                  21-day EEC
                                    (ug/L)
                             Freshwater Chronic RQ
                              (NOAEC = 5.6 ug/L)
                          Estuarine/Marine Chronic RQ
                            (NOAEC <0.115 ug/L)
                                     2.95
                                     0.52
                                   >25.6
BOLD exceeds chronic LOC (1.0).

8.2.3	Aquatic Plants

There is not a risk concern for aquatic plants from the proposed use based on available information.  There were no LOC exceedances for listed or non-listed species (Table 17).  There is some uncertainty about risk to non-vascular aquatic plants because an acceptable study with blue green algae is not available.  There are not currently any listed non-vascular plants so the uncertainty is for non-listed species.  Blue-green algae would need to be about 33x more sensitive than Navicula pelliculosa to exceed the LOC (non-listed species).

Table 17. Risk Quotients for Aquatic Plants Exposed to Difenoconazole from the Proposed Difenoconazole Use   (TTR EEC)

                                   Peak EEC
                                    (ug/L)
                                Vascular Plant
                                 Non-listed RQ
                              (EC50 = 1900 ug/L)
                                Vascular Plant
                                   Listed RQ
                              (EC05 = 110 ug/L)
                              Non-vascular Plant
                                 Non-listed RQ
                               (EC50 = 98 ug/L)
                              Non-vascular Plant
                                   Listed RQ
                              (NOAEC = 53 ug/L)
                                     3.03
                                    0.0016
                                    0.0275
                                    0.0309
                                    0.0572

8.3	Risk Summary

The primary risk concerns from the proposed use are for chronically exposed listed and non-listed species of aquatic invertebrates (estuarine/marine), fish, birds, and mammals.  In addition, a risk concern cannot be precluded for terrestrial dicots (listed species) based on the available data.

                         Appendix 1: TerrPlant Output

Table 1. Chemical Identity.

                                 Chemical Name
Difenoconazole

                                    PC code

                                      Use
Canola

                              Application Method
Aerial

                               Application Form

                           Solubility in Water (ppm)
15

Table 2. Input parameters used to derive EECs.

                                Input Parameter
                                    Symbol
                                     Value
                                     Units

                               Application Rate
                                       A
                                     0.113

                                 Incorporation
                                       I
                                       1
                                     none

                                Runoff Fraction
                                       R
                                     0.02
                                     none

                                Drift Fraction
                                       D
                                     0.05
                                     none

Table 3. EECs for Difenoconazole.  Units in .

                                  Description
                                   Equation
                                      EEC

                              Runoff to dry areas
                                    (A/I)*R
                                    0.00226

                         Runoff to semi-aquatic areas
                                  (A/I)*R*10
                                    0.0226

                                  Spray drift
                                      A*D
                                    0.00565

                              Total for dry areas
                                ((A/I)*R)+(A*D)
                                    0.00791

                         Total for semi-aquatic areas
                              ((A/I)*R*10)+(A*D)
                                    0.02825

Table 4. Plant survival and growth data used for RQ derivation. Units are in .

                              Seedling Emergence
                               Vegetative Vigor
                                  Plant type
                                     EC25
                                    NOAEC
                                     EC25
                                    NOAEC
                                    Monocot
                                     0.111
                                     0.111
                                     0.123
                                     0.123
                                     Dicot

                                     0.123
                                     0.123

Table 5. RQ values for plants in dry and semi-aquatic areas exposed to Difenoconazole through runoff and/or spray drift.*
                                  Plant Type
                                 Listed Status
                                     Dry
                                 Semi-Aquatic
                                  Spray Drift
                                    Monocot
                                  non-listed
                                    <0.1
                                     0.25
                                    <0.1
                                    Monocot
                                    listed
                                    <0.1
                                     0.25
                                    <0.1
                                     Dicot
                                  non-listed
                                    #DIV/0!
                                    #DIV/0!
                                    <0.1
                                     Dicot
                                    listed
                                    #DIV/0!
                                    #DIV/0!
                                    #DIV/0!
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

                   Appendix 2: PRZM/EXAMS and GENEEC Outputs

Example Output of PRZM/EXAMS for Surface water (Aerial Application)
stored as NDConla_E_A.out

Chemical: Difenoconazole

PRZM environment: NDcanolaSTD.txt, modified Tueday, 29 May 2007 at 13:59:22
EXAMS environment: pond298.exv, modified Tueday, 26 August 2008 at 06:14:08
Metfile: w24013.dvf, modified Tueday, 26 August 2008 at 06:15:40

                      Water segment concentrations (ppb)

                                     Year
                                     Peak
                                     96 hr
                                    21 Day
                                    60 Day
                                    90 Day
                                    Yearly

                                     1961
                                     0.31
                                     0.26
                                     0.15
                                     0.08
                                     0.07
                                     0.02

                                     1962
                                     0.36
                                     0.31
                                     0.19
                                     0.13
                                     0.11
                                     0.07

                                     1963
                                     0.42
                                     0.36
                                     0.28
                                     0.21
                                     0.19
                                     0.13

                                     1964
                                     0.49
                                     0.44
                                     0.34
                                     0.29
                                     0.28
                                     0.21

                                     1965
                                     0.56
                                     0.51
                                     0.41
                                     0.34
                                     0.32
                                     0.28

                                     1966
                                     0.60
                                     0.55
                                     0.43
                                     0.37
                                     0.36
                                     0.31

                                     1967
                                     0.64
                                     0.59
                                     0.47
                                     0.40
                                     0.39
                                     0.35

                                     1968
                                     0.66
                                     0.61
                                     0.49
                                     0.45
                                     0.44
                                     0.38

                                     1969
                                     0.70
                                     0.65
                                     0.53
                                     0.46
                                     0.44
                                     0.41

                                     1970
                                     0.78
                                     0.72
                                     0.63
                                     0.54
                                     0.52
                                     0.45

                                     1971
                                     0.93
                                     0.86
                                     0.71
                                     0.63
                                     0.61
                                     0.52

                                     1972
                                     0.85
                                     0.79
                                     0.68
                                     0.61
                                     0.59
                                     0.56

                                     1973
                                     0.84
                                     0.79
                                     0.68
                                     0.62
                                     0.61
                                     0.56

                                     1974
                                     0.86
                                     0.81
                                     0.69
                                     0.62
                                     0.61
                                     0.57

                                     1975
                                     0.88
                                     0.83
                                     0.72
                                     0.65
                                     0.65
                                     0.60

                                     1976
                                     0.90
                                     0.85
                                     0.73
                                     0.66
                                     0.64
                                     0.61

                                     1977
                                     0.91
                                     0.85
                                     0.74
                                     0.67
                                     0.66
                                     0.62

                                     1978
                                     0.93
                                     0.88
                                     0.76
                                     0.70
                                     0.69
                                     0.65

                                     1979
                                     0.97
                                     0.91
                                     0.79
                                     0.72
                                     0.70
                                     0.67

                                     1980
                                     0.94
                                     0.88
                                     0.76
                                     0.73
                                     0.72
                                     0.67

                                     1981
                                     0.96
                                     0.92
                                     0.81
                                     0.73
                                     0.71
                                     0.68

                                     1982
                                     0.97
                                     0.91
                                     0.79
                                     0.72
                                     0.72
                                     0.68

                                     1983
                                     0.97
                                     0.92
                                     0.80
                                     0.73
                                     0.73
                                     0.70

                                     1984
                                     0.99
                                     0.94
                                     0.82
                                     0.75
                                     0.73
                                     0.71

                                     1985
                                     0.99
                                     0.93
                                     0.82
                                     0.77
                                     0.75
                                     0.71

                                     1986
                                     0.99
                                     0.94
                                     0.82
                                     0.75
                                     0.73
                                     0.71

                                     1987
                                     1.27
                                     1.17
                                     0.97
                                     0.88
                                     0.85
                                     0.74

                                     1988
                                     1.04
                                     0.98
                                     0.86
                                     0.79
                                     0.77
                                     0.75

Sorted results

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

                                     0.03
                                     1.27
                                     1.17
                                     0.97
                                     0.88
                                     0.85
                                     0.75

                                     0.07
                                     1.04
                                     0.98
                                     0.86
                                     0.79
                                     0.77
                                     0.74

                                     0.10
                                     0.99
                                     0.94
                                     0.82
                                     0.77
                                     0.75
                                     0.71

                                     0.14
                                     0.99
                                     0.94
                                     0.82
                                     0.75
                                     0.73
                                     0.71

                                     0.17
                                     0.99
                                     0.93
                                     0.82
                                     0.75
                                     0.73
                                     0.71

                                     0.21
                                     0.97
                                     0.92
                                     0.81
                                     0.73
                                     0.73
                                     0.70

                                     0.24
                                     0.97
                                     0.92
                                     0.80
                                     0.73
                                     0.72
                                     0.68

                                     0.28
                                     0.97
                                     0.91
                                     0.79
                                     0.73
                                     0.72
                                     0.68

                                     0.31
                                     0.96
                                     0.91
                                     0.79
                                     0.72
                                     0.71
                                     0.67

                                     0.34
                                     0.94
                                     0.88
                                     0.76
                                     0.72
                                     0.70
                                     0.67

                                     0.38
                                     0.93
                                     0.88
                                     0.76
                                     0.70
                                     0.69
                                     0.65

                                     0.41
                                     0.93
                                     0.86
                                     0.74
                                     0.67
                                     0.66
                                     0.62

                                     0.45
                                     0.91
                                     0.85
                                     0.73
                                     0.66
                                     0.65
                                     0.61

                                     0.48
                                     0.90
                                     0.85
                                     0.72
                                     0.65
                                     0.64
                                     0.60

                                     0.52
                                     0.88
                                     0.83
                                     0.71
                                     0.63
                                     0.61
                                     0.57

                                     0.55
                                     0.86
                                     0.81
                                     0.69
                                     0.62
                                     0.61
                                     0.56

                                     0.59
                                     0.85
                                     0.79
                                     0.68
                                     0.62
                                     0.61
                                     0.56

                                     0.62
                                     0.84
                                     0.79
                                     0.68
                                     0.61
                                     0.59
                                     0.52

                                     0.66
                                     0.78
                                     0.72
                                     0.63
                                     0.54
                                     0.52
                                     0.45

                                     0.69
                                     0.70
                                     0.65
                                     0.53
                                     0.46
                                     0.44
                                     0.41

                                     0.72
                                     0.66
                                     0.61
                                     0.49
                                     0.45
                                     0.44
                                     0.38

                                     0.76
                                     0.64
                                     0.59
                                     0.47
                                     0.40
                                     0.39
                                     0.35

                                     0.79
                                     0.60
                                     0.55
                                     0.43
                                     0.37
                                     0.36
                                     0.31

                                     0.83
                                     0.56
                                     0.51
                                     0.41
                                     0.34
                                     0.32
                                     0.28

                                     0.86
                                     0.49
                                     0.44
                                     0.34
                                     0.29
                                     0.28
                                     0.21

                                     0.90
                                     0.42
                                     0.36
                                     0.28
                                     0.21
                                     0.19
                                     0.13

                                     0.93
                                     0.36
                                     0.31
                                     0.19
                                     0.13
                                     0.11
                                     0.07

                                     0.97
                                     0.31
                                     0.26
                                     0.15
                                     0.08
                                     0.07
                                     0.02

                                     0.10
                                     1.00
                                     0.95
                                     0.83
                                     0.77
                                     0.75
                                     0.71

                          Average of yearly averages:
                                     0.51

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: NDConla_E_A

Metfile:
w24013.dvf

PRZM scenario:
NDcanolaSTD.txt

EXAMS environment file:
pond298.exv

Chemical Name:
Difenconazole

Description
Variable Name
Value
Units
Comments

Molecular weight
mwt
                                                                         406.27
g/mol

Henry's Law Const.
henry
                                                                       8.90E-12
atm-m^3/mol

Vapor Pressure
vapr
                                                                       2.50E-10
torr

Solubility
sol
                                                                             15
mg/L

Kd
Kd

mg/L

Koc
Koc
                                                                           5381
mg/L

Photolysis half-life
kdp
                                                                              0
days
Half-life

Aerobic Aquatic Metabolism
kbacw
                                                                            556
days
Halfife

Anaerobic Aquatic Metabolism
kbacs
                                                                           1110
days
Halfife

Aerobic Soil Metabolism
asm
                                                                            313
days
Halfife

Hydrolysis:
pH 7
                                                                              0
days
Half-life

Method:
CAM
                                                                              2
integer
See PRZM manual

Incorporation Depth:
DEPI

cm

Application Rate:
TAPP
                                                                          0.127
kg/ha

Application Efficiency:
APPEFF
                                                                           0.95
fraction

Spray Drift
DRFT
                                                                           0.05
fraction of application rate applied to pond
Application Date
Date
18-07
dd/mm or dd/mmm or dd-mm or dd-mmm
Record 17:
FILTRA

IPSCND
                                                                              1

UPTKF

Record 18:
PLVKRT

PLDKRT

FEXTRC
                                                                            0.5

Flag for Index Res. Run
IR
EPA Pond

Flag for runoff calc.

RUNOFF
none
none, monthly or total(average of entire run)
Example Output of PRZM/EXAMS for Porewater (Aerial Application)

stored as NDConla_E_Aben.out

Chemical: Difenconazole

PRZM environment: NDcanolaSTD.txt, modified Tueday, 29 May 2007 at 13:59:22
EXAMS environment: pond298.exv, modified Tueday, 26 August 2008 at 06:14:08
Metfile: w24013.dvf, modified Tueday, 26 August 2008 at 06:15:40
                     Benthic segment concentrations (ppb)

                                     Year
                                     Peak
                                     96 hr
                                    21 Day
                                    60 Day
                                    90 Day
                                    Yearly
                                     1961
                                     0.04
                                     0.04
                                     0.04
                                     0.04
                                     0.04
                                     0.02
                                     1962
                                     0.08
                                     0.08
                                     0.08
                                     0.08
                                     0.08
                                     0.06
                                     1963
                                     0.15
                                     0.15
                                     0.15
                                     0.15
                                     0.15
                                     0.11
                                     1964
                                     0.24
                                     0.24
                                     0.24
                                     0.24
                                     0.24
                                     0.19
                                     1965
                                     0.28
                                     0.28
                                     0.28
                                     0.28
                                     0.28
                                     0.25
                                     1966
                                     0.31
                                     0.31
                                     0.31
                                     0.31
                                     0.31
                                     0.29
                                     1967
                                     0.34
                                     0.34
                                     0.34
                                     0.34
                                     0.34
                                     0.32
                                     1968
                                     0.38
                                     0.38
                                     0.38
                                     0.38
                                     0.38
                                     0.35
                                     1969
                                     0.40
                                     0.40
                                     0.40
                                     0.40
                                     0.40
                                     0.38
                                     1970
                                     0.45
                                     0.45
                                     0.45
                                     0.45
                                     0.45
                                     0.42
                                     1971
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.47
                                     1972
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.53
                                     1973
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.54
                                     0.53
                                     1974
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.54
                                     1975
                                     0.59
                                     0.59
                                     0.59
                                     0.59
                                     0.58
                                     0.56
                                     1976
                                     0.59
                                     0.59
                                     0.59
                                     0.59
                                     0.58
                                     0.58
                                     1977
                                     0.60
                                     0.60
                                     0.60
                                     0.60
                                     0.60
                                     0.58
                                     1978
                                     0.62
                                     0.62
                                     0.62
                                     0.62
                                     0.62
                                     0.61
                                     1979
                                     0.64
                                     0.64
                                     0.64
                                     0.64
                                     0.64
                                     0.62
                                     1980
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.63
                                     1981
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.64
                                     1982
                                     0.66
                                     0.66
                                     0.66
                                     0.66
                                     0.66
                                     0.64
                                     1983
                                     0.67
                                     0.67
                                     0.67
                                     0.67
                                     0.67
                                     0.65
                                     1984
                                     0.68
                                     0.68
                                     0.68
                                     0.67
                                     0.67
                                     0.66
                                     1985
                                     0.68
                                     0.68
                                     0.68
                                     0.68
                                     0.68
                                     0.66
                                     1986
                                     0.68
                                     0.68
                                     0.68
                                     0.67
                                     0.67
                                     0.67
                                     1987
                                     0.75
                                     0.75
                                     0.75
                                     0.74
                                     0.74
                                     0.68
                                     1988
                                     0.73
                                     0.73
                                     0.73
                                     0.73
                                     0.73
                                     0.71

Sorted results

Prob.
Peak
96 hr
21 Day
60 Day
90 Day
Yearly
                                     0.03
                                     0.75
                                     0.75
                                     0.75
                                     0.74
                                     0.74
                                     0.71
                                     0.07
                                     0.73
                                     0.73
                                     0.73
                                     0.73
                                     0.73
                                     0.68
                                     0.10
                                     0.68
                                     0.68
                                     0.68
                                     0.68
                                     0.68
                                     0.67
                                     0.14
                                     0.68
                                     0.68
                                     0.68
                                     0.67
                                     0.67
                                     0.66
                                     0.17
                                     0.68
                                     0.68
                                     0.68
                                     0.67
                                     0.67
                                     0.66
                                     0.21
                                     0.67
                                     0.67
                                     0.67
                                     0.67
                                     0.67
                                     0.65
                                     0.24
                                     0.66
                                     0.66
                                     0.66
                                     0.66
                                     0.66
                                     0.64
                                     0.28
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.64
                                     0.31
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.65
                                     0.63
                                     0.34
                                     0.64
                                     0.64
                                     0.64
                                     0.64
                                     0.64
                                     0.62
                                     0.38
                                     0.62
                                     0.62
                                     0.62
                                     0.62
                                     0.62
                                     0.61
                                     0.41
                                     0.60
                                     0.60
                                     0.60
                                     0.60
                                     0.60
                                     0.58
                                     0.45
                                     0.59
                                     0.59
                                     0.59
                                     0.59
                                     0.58
                                     0.58
                                     0.48
                                     0.59
                                     0.59
                                     0.59
                                     0.59
                                     0.58
                                     0.56
                                     0.52
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.54
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.55
                                     0.54
                                     0.53
                                     0.59
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.53
                                     0.62
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.54
                                     0.47
                                     0.66
                                     0.45
                                     0.45
                                     0.45
                                     0.45
                                     0.45
                                     0.42
                                     0.69
                                     0.40
                                     0.40
                                     0.40
                                     0.40
                                     0.40
                                     0.38
                                     0.72
                                     0.38
                                     0.38
                                     0.38
                                     0.38
                                     0.38
                                     0.35
                                     0.76
                                     0.34
                                     0.34
                                     0.34
                                     0.34
                                     0.34
                                     0.32
                                     0.79
                                     0.31
                                     0.31
                                     0.31
                                     0.31
                                     0.31
                                     0.29
                                     0.83
                                     0.28
                                     0.28
                                     0.28
                                     0.28
                                     0.28
                                     0.25
                                     0.86
                                     0.24
                                     0.24
                                     0.24
                                     0.24
                                     0.24
                                     0.19
                                     0.90
                                     0.15
                                     0.15
                                     0.15
                                     0.15
                                     0.15
                                     0.11
                                     0.93
                                     0.08
                                     0.08
                                     0.08
                                     0.08
                                     0.08
                                     0.06
                                     0.97
                                     0.04
                                     0.04
                                     0.04
                                     0.04
                                     0.04
                                     0.02

                                     0.10
                                     0.69
                                     0.69
                                     0.69
                                     0.69
                                     0.68
                                     0.67

                          Average of yearly averages:
                                     0.48

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: NDConla_E_A

Metfile:
w24013.dvf

PRZM scenario:
NDcanolaSTD.txt

EXAMS environment file:
pond298.exv

Chemical Name:
Difenconazole

Description
Variable Name
Value
Units
Comments

Molecular weight
mwt
                                                                         406.27
g/mol

Henry's Law Const.
henry
                                                                       8.90E-12
atm-m^3/mol

Vapor Pressure
vapr
                                                                       2.50E-10
torr

Solubility
sol
                                                                             15
mg/L

Kd
Kd