### 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 , 201 3 **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., Ec ologist

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 I nspire ® 

### 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 recentl y 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).

### 2

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 ®

### ) on canola and oilseed subgroup 20A . Difenoconazole is a fungicide in the conazole chemical class. Fungicidal activity of the conaz ole class is attributed to the inhibition of ergosterol biosy nthesis. A number of risk assessments have been conducted on difenoconazole. Previous assessments identified risk concerns primaril y 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

– mo nocots

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.

### 3 **Listed Taxa Direct Effects**  **1 Indirect Effects**  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 estab lished 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 es tablished at the maximum labeled single application rate.

 There is uncertainty associated with chronic risk to benthic invertebrates gi ven that porewater EECs are similar to water column EECs and a lack of acceptable toxicity data for benthic invertebrate s . 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 i n 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

### 4

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 (nondefinitive endpoint) and benthic invertebrates (lack of data). Th ere 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 alg ae 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 - onl y EEC = 0.77 μg/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]triazo l - 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 addre ssed 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 ty pically 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

**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 1 

### . Ergosterol, which controls cell membrane permeability, is a critical component in fungal cell membranes 2 

### . The mechanism of controlling ergosterol biosynthesis is through the disruption of the fungal cy tochrome 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 measur ed 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 - me thyl - 1,3 - dioxolan- 2 - yl) - methyl]} - 1H - 1,2,4 - triazole MRID 469501 - 04

SMILES notation O1CC(C)OC1(Cn2ncnc2)c3c(Cl)cc(O c4ccc(Cl)cc4)cc3 EPI Suite, v3.12 SMILES Molecular Formula C 19 H 17 Cl 2N 3 O 3 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

1 www.centerwatch.com/patient/drugs/dru784.html 2 www.hull.ac.uk/php/chsanb/fungweb/fungweb7.htm

### 6 **Property Value**  **Source** Henry’s Law constant 8.9 x 10 - 12 atm x m3 /mol MRID 465159 - 01 Specific Gravity/ Density 1.14g/cm3 @ 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 slightl y m obile. 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 b ottom sediment as shown in an aerobic aquati c metabolism study (MRID 422451 34), 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 relativel y 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 m3 /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

### 7 **Property Value**  **Source** 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 halflife 947 days

– at 10 ppm in loam MRID 422451 - 32 Aerobic aquatic metabolism halflife 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 halflife 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 w

hole 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 46 9501 - 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/cm2 ) , as a result, a range of half - lives was obtained. **D** Inthose aerobic soil metabolism studies (MRI D 422451 - 32 and MRID 422451 - 33) the test application rate was significantly higher than expected under registrant -proposed use condition for difenoconazole. **E** Inthose aquatic metabolism studies, the test application rates were significantly higher than expected under registrant-proposed use condition for difenoconazole.

### 8

**6 .**  **Exposure Summary 6**  **.1 Terrestr** **ial 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 ) 3 

### ( **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**  **(gram s)**  **Dietary and Dose -**  **Based EECs 1** 

**Short Grass Tall Grass**  **Broadleaf Plants**  **Fruits/Pods/**

**Seeds Arthropods**  **Mam mals**  **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. 2.98.04.06) modeling with the standard pond scenario. Detailed description s of these models can be found in a previous assessment (DP377719, 7/20/2 010). Separate EECs were calculated for difenoconazole and its total toxic residues (TTR). Difenoconazole - onl y EECs were used to assess risk when data w ere available that indicated th at the major degradates were less toxic than difenoconazole (acute risk to fish and invertebrates) . This approach is different than that used in recent risk assessment s ( DP377719, 7/20/2 010 and DP37 8927+ , 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 assessment s , TTR EECs were use d 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** 

3 www.epa.gov/oppefed1/models/terrestrial/index.htm

### 9

The PRZM/EXAMS input parameters for difenoconazole are shown in **Table 5**  . Inputs are equivalent to those used in previous asses sments ( 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**

**Param eter**  **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 mo deled 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 m3 /mol MRID 46515901 Hydrolysis Stable MRID 42245127 Aerobic soil metabolism (t 1/2 ) b 313 days MRIDs: 42245131, 46950109 - 12, and 46950114 Aerobic aquatic metabolism (t 1/2 ) c 556 days MRIDs: 46950116 & 46950117 Anaerobic aquatic metabolism (t 1/2 ) d 1110 days MRID 46950119 Aquatic photolysis t 1/2 (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 wa s 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**

### 10

**Water Source**  **(m odel)**  **Use**

**Scenario (rate and interval)**  **Application Me** **thod Peak EEC** 

**( μg/L**  **) 21**  **- Day** 

**EEC ( μg/L**  **) 60**  **- Day** 

**EEC (**  **μg/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, ye arly 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 - li fe, 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 . 4 

### Twelve surface water and sediment samples collected in California and Georgia were anal yz ed for difenoconazole. D ifenoconazole was detected in onl y one of twelve surface water samples; the reported maximum concentration ( 18.2 ng/L) was detected in California. Difenoconazole was not detected in s ediment samples (limit of quantitation (LO Q) was 0.6 μg/kg - sediment). NAQWA monitoring data w ere not targeted specificall y to difenoconazole use areas or during times of known difenoconazole use; thus, the dataset may

not reflect pe ak 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 5



### . D ifenoconazole monitoring data were not available.

4 http://water.usgs.gov/nawqa/pnsp/ 5 http://www.cdpr.ca.gov/docs/emon/ehap.htm

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**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 recentl y 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 LD 50 

### > 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 solel y to the observed abnormal heart function in that bird. No other effects were noted. The study is acceptable. The 96 - hr LC 50 

### 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 a nd 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 μg ai/L. The LOAEC was 3.7 μg 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 she epshead minnow data (acute) to estimate chronic toxicity to marine/estuarine fish. The recentl y submitted terrestrial plant studies (MRID 48453203 and 48453204) showed no statistically

significant effects at the limit test concentration (0.11 1/0.112 lb ai/A for seedling emergence and 0.12 3 lb ai/A for vegetative vigor). However, in the seedling emergence study , the lack of statistical significance for three of the dicots (lettuce, so ybean, and sugar beet) may have been due to high experimental variability and the magnitude of some of the effects is considered potentiall y biologicall y significant. Lettuce showed reduced emergence (21%), survival (17%), shoot length (26%), and dry weight (24%). Soy

bean showed reduced shoot length (23%). Sugar beet showe d 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).

### 12

**Table 7**  **. Summary of Most Sensitive Aquatic Toxicity Endpoints for Difenoconazole**  **Type of Study Species**  **Toxicity Value (μg ai/L)**  **MRID** Ac ute

– Freshwater Fish Rainbow trout

( Oncorhynchus mykiss ) 96 -hr LC 50 **=** 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 - Ac ute

– Freshwater Invertebrate Water flea

( Daphnia magna ) 48 -hr EC 50 = 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 ) EC 50 >50 mg ai/kg - sediment (nominal) NOAEC = 5 mg ai/kg - sediment (nominal) based on emergence rate & development rate 47648601 Ac ute

– Estuarine/Marine Fish Sheepshead minnow

( Cyprinodon variegates ) 96 -hr LC 50 **=** 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 - Ac ute

– Estuarine/Marine Mollusk Eastern oyster

( Crassostrea virginica ) 96 -hr EC 50 = 424 42906701 Ac ute

– Estuarine/Marine Invertebrate Mysid shrimp

( Americamysis bahia ) 96 -hr LC 50 = 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 ) EC 50 = 1900 EC 05 = 110 NOAEC < 110 LOAEC ≤ 100 based on reduced frond number 46920504 Non - vascular Plant

– Freshwater Diatom

( Navicula pelliculosa ) EC 50 = 98 NOAEC = 53 LOAEC = 150 based on reduced cell density 46920508 1 Ac ute toxicity to fathead minnow: LC 50 = 1800 μg ai/L (MRID 48453201) 

### Table **8 .**  **Summary of Most Sensitive Terrestrial Toxicity Endpoints for Difenoconazole Type of Study**  **Species Toxicity Value**  **MRI D** 

### 13

**Type of Study Species**  **Toxicity Value MRI** **D** Ac ute

– Avian Oral Dose Canary

(Serinus canaria ) LD 50 > 2000 mg ai/kg -bw 48453202 Ac ute

– Avian Dietary Bobwhite quail

( Colinus virginianus ) LC 50 = 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 Ac ute

– Mammalian Oral Dose Laboratory rat

(Rattus norvegicus ) LD 50 = 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 Ac ute

– Contact Honey bee

( Apis mellifera ) LD 50 >100 μg ai/bee 42245124 Ac ute

– Contact Earthworm LC 50 > 610 mg ai/kg - dw 42245125 Terrestrial Plants Corn, Onion, Ryegrass,

Wheat, Radish, Cabbage, Lettuce, Sugar beet, Soy bean, and Tomato Seedling Emergence

EC 25 > 0.111/0.112 lb ai/A 1 NOAEC ≥ 0.111/0.112 lb ai/A 1 ,2 Vegetative Vigor EC 25 > 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 len gth (26%), and dry weight (24%). Soybean showed reduced shoot length (23%). Sugar beet showed reduced survival (18%). 

### 1,2, 4 - triazole The recentl y 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 L C 50 

### = 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 E C 50 

### > 98.1 mg ai/Lfor 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 LC 50 

### > 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 earl y life stage (ELS) studies submitted on difenoconazole . EL S studies are designed to examine effects such as hatching success and larval survival in addition to growth of earl y 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 o n birds (MRID 45284015), earthworms (MRID 45297201), daphnids (MRID 00133381), fish (MRID 45284017), and algae (MRID 00133382). The data suggest that

### 14

1,2,4 - triazole may

be less toxic than difenoconazole to fish, daphnids, and aquatic plants, but more toxi c 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 markedl y 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) metho ds 6 

### 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**  **(μg ai/L) MRID**  Ac ute

– Freshwater Fish Rainbow trout

( Oncorhynchus mykiss ) 96 -hr LC 50 **=** 498,000 48474301 Ac ute

– Freshwater Invertebrate Water flea

( Daphnia magna ) 48 -hr EC 50 > 98,100 48453206 

### Triazole Acetic Acid The recentl y reviewed studies with triazole acetic acid indicate that it is less acutel y toxic than difenoconazole to freshwater fish and invertebrates. Both studies are acceptable. The 96 - hr L C 50 

### > 101 mg ai/L for rainbow trout (MRID 48453209) ; no mortality or sublethal effects were reported . The 48 - hr E C 50 

### > 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 tha n 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 - def initive 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 (μg ai/L)**  **MRID** Ac ute

– Freshwater Fish Rainbow trout

( Oncorhynchus mykiss ) 96 -hr LC 50 **>** 101,000 48453209 Ac ute

– Freshwater Water flea 48 -hr EC 50 > 108,000 48453208 6 ECOSAR predictive software is available publically though the Epi SuiteTM program . http://www.epa.gov/oppt/exposure/pubs/episuite.htm

### 15

**Type of Study Species**  **Toxicity Value (μg ai/L)**  **MRID** Invertebrate ( Daphnia magna ) 

### 7 **.1 Incidents**  Reviews were conducted of the Ecological Incident Information System (EIIS, version 2.1.1) 7 

### , the Agency ’s Aggregated Incidents Reports database, and the Avian Incident Monitoring System (AIMS) 8 

### 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 ®

### ) 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 th en 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 (RQ s < 0.0 1 ). 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 LD 50 

### ); 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 Quotient s 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

7 http://www.epa.gov/espp/consultation/ecorisk - overview.pdf 8 http://www.abcbirds.org/abcprograms/policy/toxins /aims/aims/index.cfm

### 16 **Feeding Category Acute Dietary** **- based RQs**  **Chronic Dietary -**  **based RQs** 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 1 2**  ) . Chronic dietary- based RQs exceed the LOC fo r 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 (RQ s = 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, soy bean, and sugar beet) may have been due to the high experimental variability and the magnitude of some of the effects is considered potentially biologicall y significant. Lettuce showed reduced emergence (21%), survival (17%), shoot length (26%), and dry weight (24%). Soy bean showed reduced shoot length (23%). Sugar beet showed reduced survival (18%). There is not a risk concern for non - listed dicots assuming that the EC 25 

### = 0.111 /0.112 lb ai/A (the test concentration 9 

### ) ; this may be a reasonable assumption given that the maximum observed effect w as 26% . Risk to listed dicot species cannot be precluded given the magnitude of the observed inhibition at 0.111 lb ai/A for lettuce, so yb ean, and sugar beet . The NOA E C 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, soy

bean, and sugar beet would reduce uncertainty for listed dicot species. At

9 Some species were exposed to 0.111 lb ai/A and others were exposed to 0.112 lb ai/A.

### 17

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 contactbased 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 μ g ai/bee) 10 

### is less than 1/2.5 11 

### of the non - definitive LD 50 

### (>100 μg ai/bee)

. 

### Acute contact testing of difenoconazole on earthworms resulted in an LC 50 

### 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 base d 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 order s of magnitude below the earthworm NOAEC; therefore, there was no t 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 (RQ s < 0. 0 1 ) . 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 no t be a chronic risk concern for fish if the degradates are

10 The EEC = 0.113 lb ai/A * 2.7 μ g ai/bee per lb ai/A = 0.3051 μ g ai/bee 11 The LOC for bees is 0.4

### 18

less toxic than difenoconazole (RQ = 0.89 based on a 60 - day difenoconazole - only

EEC = 0.77 μg/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 (**  **μg/L )**  **Freshwater Acute RQ**  **(LC 50**  **= 810 μg/L**  **) Estuarine/Marine**  **Acute RQ (LC**  **50 = 819**  **μg/L )**  1 < 0.0 1 < 0.01 

### Table 14. Chronic Risk Quotients for Freshwater and Estuarine/Marine Fish Exposed from **the Proposed Difenoconazole Use**  **(TTR EEC)**

**60 -**  **day EEC (**  **μg/L )**  **Freshwater and Estuarine/Marine Chronic RQ**  **(NOAEC = 0.86 μg/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 (RQ s < 0.0 1 ). The chronic LOC (1 .0) was not exceeded f or freshwater invertebrates (RQ = 0.52) ; h owever, the LOC was exceeded for estuarine/marine invertebrates (RQ > 25.6 ). There is a chronic risk concern for aquatic invertebrate s (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 476486 01) 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 12 

### (se e **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 no t 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); h owever, 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 invertebrate s given that benthic species may be more sensitive than water column species.

12 GENNEC currently does not provide porewater co ncentrations; therefore, difenoconazole - only EECs were calculated instead of TTR EECs for considering risk to benthic invertebrates.

### 19

**Table 15. Acute Risk Quotients for Freshwater and Estuarine/Marine Invertebrates**  **Exposed from the Proposed Difenoconazole Use**  **(Difenoconazole EEC )**  **Peak EEC**  **( μg/L**  **) Freshwater**  **Acute RQ (LC**  **50 = 770**  **μg/L )**  **Estuarine/ Marine Acute RQ**  **(LC 50**  **= 150 μg/L**  **)** 1 < 0.0 1 < 0.0 1 

### Table 16. **Chronic Risk Quotients for Freshwater and Estuarine/Marine Invertebrates Exposed from the Proposed Difenoconazole**  **Use (TTR EEC**  **) 21**  **- day EEC**  **( μg/L**  **) Freshwater Chronic RQ** 

**(NOAEC = 5.6 μg/L)**  **Estuarine/Marine Chronic RQ (NOAEC <0.115**  **μg/L)** 2.95 0.52 **>25.6 BOLD**  exceeds chronic LOC (1.0). 

### 8 **.2.3 Aquatic Plants**  There is no t 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 currentl y 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**  **( μg/L**  **) Vascular Plant** 

**Non -**  **listed RQ (EC**  **50 = 1900**  **μg/L )**  **Vascular Plant Listed RQ**  **(EC 05**  **= 110 μg/L) Non**  **- vascular Plant** 

**Non -**  **listed RQ (EC**  **50 = 98 μg/L)**  **Non -** **vascular Plant Listed RQ**  **(NOAEC = 53 μg/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 chronicall y exposed listed and non listed species of aquatic invertebrates (estuarine/marine) , fish, birds, and mammals. Inaddition, a risk concern cannot be precluded for terrestrial dicots (listed species) based on the available data.

### 20 **Appendix 1: TerrPlant Output Table 1. Chemical Identity.**  **Chemical Name Difenoconazole**  **PC code Use**  **Canola Ap**  **plication Method Aerial**  **Ap plication 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**  **EC 25**  **NOA EC**  **EC 25**  **NOA EC**  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**  **- Aq**  **uatic 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.

### 21 **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 segm ent 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

### 22

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 environm ent file: pond298.exv Chemical Name: Difenconazole Descripti Variable Value Units Comments

### 23

on Name Molecula r 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 Photolysi s half - life kdp 0 days Half - life Aerobic Aquatic Metabolis m kbacw 556 days Halfife Anaerobi c Aquatic Metabolis m kbacs 1110 days Halfife Aerobic Soil Metabolis m asm 313 days Halfife Hydrolysi s: pH 7 0 days Half - life Method: CAM 2 integer See PRZM manual Incorpora tion Depth: DEPI cm Applicati on Rate: TAPP 0.127 kg/ha Applicati on Efficienc y: APPEFF 0.95 fraction Spray Drift DRFT 0.05 fraction of application rate applied to pond Applicati on 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 RUNOFF none none, monthly or total(average of entire run)

### 24

calc. 

### 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

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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 environm ent file: pond298.exv Chemical Name: Difenconazole Descripti on Variable

Name Value Units Comments Molecula mwt 406.27 g/mol

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r weight 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 Photolysi s half - life kdp 0 days Half - life Aerobic Aquatic Metabolis m kbacw 556 days Halfife Anaerobi c Aquatic Metabolis m kbacs 1110 days Halfife Aerobic Soil Metabolis m asm 313 days Halfife Hydrolysi s: pH 7 0 days Half - life Method: CAM 2 integer See PRZM manual Incorpora tion Depth: DEPI cm Applicati on Rate: TAPP 0.127 kg/ha Applicati on Efficienc y: APPEFF 0.95 fraction Spray Drift DRFT 0.05 fraction of application rate applied to pond Applicati on 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)

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**Example Output of GENEEC**  **Aerial Application** RUN No. 1 FOR Difenoconazole ON Oilseed * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO - SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN)

-------------------------------------------------------------------- .113( .113) 1 1 1000.0 15.0 AERL_B( 13.0) .0 .0 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS)

------------------------------ -------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND - EFF) (POND) (POND)

-------------------------------------------------------------------- .00 2 N/A .00 - .00 .00 .00 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001

-------------------------------------------------------------------- PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

-------------------------------------------------------------------- 3.03 3.01 2.95 2.80 2.70 

### Ground Application RUN No. 2 FOR Difenconazole ON Canola * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO - SPRAY INCORP ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN)

-------------------------------------------------------------------- .113( .113) 1 1 1000.0 15.0 GRHIFI( 6.6) .0 .0 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (POND) (POND - EFF) (POND) (POND)

------------------------------------- ------------------------------- .00 2 N/A .00 - .00 .00 .00 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001

-------------------------------------------------------------------- PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

-------------------------------------------------------------------- 2.74 2.73 2.67 2.53 2.44

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