UNITED STATES ENVIRONMENTAL PROTECTION 

AGENCY 

OFFICE OF CHEMICAL SAFETY 

ANO POLLUTION PREVENTION 

PC Code: 122101 

DP Barcode: 423648 

May 27, 2015 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

Drinking Water Assessment for Proposed New Uses of Propiconazole on Dill, 

Radish, Leafy Brassica Subgroup SB, Watercress, Ti palm and Crop Group 

conversions for Stone Fruit Group 12-12 and Tree Nut Group 14-12. 

Ibrahim Abdel-Saheb, Ph.D, Environmental Scientist , - ~ 5 / l T / / f 

Environmental Risk Branch VJ 

Environmental Fate and Effects Division (7507P) {' (/ 

Mark Corbin, Branch Chief . p/ J / / ~ 6 · 21-\) 

Willi.am P. ~ckel, Ph.D., Senior Scienc~~ .. / // ' f !:") / /} -j J .- Monica Wait, RAPL / !/£/~ . ~ ~ Z 7 /~ 

Environmental Risk Branch VI ~ w ~ 5. 

Environmental Fate and Effects Division (7507P) 12. 7 / l 5 

Thurston Morton, Risk Assessor 

RAB4 

Health Effects Division (7509P) 

Driss Benmhend, Risk Manager Reviewer 

Shaja Joyner, Product Manager Team 20 

Fungicide-Herbicide Branch 

Registration Division (7505 P) 

Sidney Jackson, Risk Manager Reviewer 

Barbara Madden, Minor Use Team Leader Product Manager 5 

Minor Use and Emergency Response Branch 

Registration Division (7505 P) 

This memorandum provides estimates of human drinking water exposure to propiconazole (a 

broad spectrum fungicide for control of plant, turf and ornamental diseases) from the proposed 

new uses on dill, radish, leafy brassica subgroup SB, watercress, Ti palm and crop group conversions 
for Stone Fruit Group 12-12 and Tree Nut Group 14-1 2. 

Note that this assessment incorporates new models implemented since the previous EDWC and 

therefore a comparison of EDWCs are shown in Table I below. Model inputs and outputs are 

included in Appendix I Thus, EFED recommends that the Hea lth Effects Division use the 

following surface water and groundwater EDWCs (highlighted fields) resulting from modeling. 

Please note that while the surface water EDWC have decreased and the groundwater EDWC 

have increased since the 2006 drinking water assessment (whi ch is the source of previous high 

EDWC) the overall recommended EDWC for groundwater are still lower than those previously 

recommended for risk assessment. . 

Table l. Estimated Drinking Water Concentrations (EDWCs) for proposed new uses and previously 

registered turf. 

Use on Turf 

Surface water Surface water 

2006 Modeling 2015 Modeling 

(PRZM/EXAMS)* (SWCC)** 

Dill 

Peak (ppb) 76.5 Peak (I -in- I 0 35.2 2.84 

yr) 

Annual Mean (ppb) 37.5 365-day Avg 18.6 1.35 

(I -in- I 0 yr) 

30-Year Mean (ppb) 26.4 Entire 14.4 1.04 

Simulation 

Mean ~ 

SCI- PRZM-GW*** 

Groundwater GROW 

EDWCs (ppb) Peak 37.9 1.84 

Concentration 

(oob) 

Post- jS, I 1.66 

0.64 Breakthrough 

Mean 

Concentration 

(ppb) 

Entire 26.4 1.25 

Simulation 

Mean 

Concentration 

(oob) 

•Based on PAturfsccnano (lughcst model output) 

• • Two scenarios "ere run and highest model output is presented in this table. 

For the SWCC model: the following available turf scenarios were used· 

FL. and PA 

The Pennsylvania sccnnrio gave the highest EDWCs. 

••• For the PRZi\1-GW model: 1hc following available scenarios "ere used: 

New Uses 

Surface water 

2015 Modeling 

(SWCC) 

Radish Wmcrcrcss Ti Palm 

18.4 15.9 8.69 

2.68 3.65 2.25 

1.76 2.61 1.69 

PRZM-GW 

2.47 2.47 2.47 

2.23 ? ?" -·-"' 2.23 

1.67 1.67 1.67 

Fl.potaio. Fl. citrus. GA coaswl. and NCcoasial. and Wlsand. The Wlsand scenario gave lhc highest EDWCs. 

2 

Stone 

Fruit (12-

12) 

3.55 

1.61 

1.35 

3. 17 

2.85 

2.14 

Tree Nut 

( 14-12) 

4.88 

2.68 

2.36 

4.4 1 

3.99 

2.99 
The propiconazole end-use products associated with the proposed new uses are Quilt (EPA Reg 

No. I 00-1178); Inspire® XT (EPA Reg No. 100-1312); Tilt (EPA Reg No. I 00-617); and Qui lt 

Xcel® (EPA Reg No. 100-1324). These products may be applied by ground, air, or chemigation. 

The proposed use rates are tabulated below based on the submitted labels. The tree nuts use site 

(subgroup I 4-12) has the highest proposed maximum single application rate (0.225 lb a.i./ A) and 

the highest annual application rate (0.90 lb a.i./A) of the proposed uses. 

Crop Use Rate (lb No. App Total Use Data Source 

a.i./A) (Interval Rate/Season (lb 

in days) a.i./A) 

Dill 0.1 125 3 (7- 10) 0.34 EPA Reg. No. 100-617, -

1178, -1324 

Radish 0. 1125 4 (7- 10) 0.45 EPA Reg. No. 100-617, -

Watercress 1178, -1324 

Ti Palm 

Stone Fruit ( 12- 12) 0.1 125 5 ( 10-14) 0.56 EPA Reg. No. 100-6 17, -

1178, -1312, - 1324 

Tree Nut (14- 12) 0.225 4 (7- 14) 0.90 EPA Reg. No. 100-617, -

1178,-1324,- 13 12 

Physical/Chemical/Fate and Transport Properties 

Propiconazole is an amber to ye llow viscous liquid with a boiling point of 95 "C, density of 

1.27 g/cm3, octanol/water partition coefficient (log Kaw) of 2.95, and vapor pressure of 1.0 x Io6 Torr at 20 °C. Propiconazole is slightly soluble in water ( 100 ppm at 20 °C), practically 

insoluble in hexane (0.06 ppm), and is miscible with most organic solvents, including methanol, 

isopropanol, acetone, methylene chloride, toluene, and n-octanol. 

Propiconazole appears to be persistent and moderately mobile to relative immobile in most soil 

environments. In the aquatic environment, propiconazole degradation appears to be dependent 

solely on aqueous photolysis in the presence of photo sensitizers. In soil environment, 

propiconazole dissipation appears to depend on incorporation or binding to soil organic matter 

content. 

Laboratory and terrestrial field dissipation data indicate that propiconazole is stable in soil and 

aqueous environments. However, in supplemental aquatic dissipation data using basin-irrigation 

and flow through irrigation systems in rice fields, propieonazole was found to be dissipated 

rapidly (t 112 < 5 days). Aqueous photolysis studies using sensitizers indicated rapid degradation 

(t112 < 1 days) of propiconazole, which appears to be the case in rice fields. Furthermore, aquatic 

3 
metabolism and dissipation studies indicate propiconazole dissipates by incorporation or binding 

into the organic matter content of soil/sediment. 

Propiconazole mobility in soil appears to be dependent on the soil's organi c matter content. In 

general, propiconazole appears to be moderately mobile (Kd < 5) in soils with a low organic 

matter content(< 1 %). However, in soils with higher organic matter content(> I %), 

propiconazole appears to be relatively immobile (Kd > 5). Therefore, propiconazole may reach 

ground water in soils with low organic contents. Propiconazole may also contaminate surface 

water through off-site runoff and spray drift. 

Modeling 

In the case of propicanazole, turf, a previously registered use, has the highest application rate of all 

cuITently registered uses (7.2 lb a.i./A/Year, 4 appli cations of 1.78 lb a.i./A with a 14-day interval 

between applications) (drinking water assessment, DP 323440, 617/2006). Thus, turfrepresents the 

most conservative modeling scenario for propiconazole. 

The Tier 2 (PRZM-EXAMS) models were used in the 2006 drinking water assessment (OWA) 

cited above and resulted in the following estimated drinking water concentrations (EDWCs) for 

surface water: 76.5 ppb peak exposure, 37.5 ppb annual mean. For groundwater, the model SCIG ROW gave acute and chronic EDWCs of 0. 64 ppb. 

Since 2006, EFED has introduced new surface water and groundwater models [i.e Surface Water 

Concentration Calculator (SWCC), and PRZM-GW, respectively]. A comparison was made 

between output from current EFED models for propiconazole for the proposed uses o n dill, 

radish, leafy brassica Subgroup 5B (0.34 lb a.i./A/season); radish, watercress, and Ti 

palm (0.45 lb a.i./A/season); crop group conversions for Stone Fruit Group 12- 12 (0.56 lb 

a.i./A/season); Tree Nut Group 14-12 (0.90 lb a.i./A/season) with the output from the currently 

registered use on turf (4 applications of0.786 lb a.i . ./A per year with a 14-day interval between 

applications). For watercress modeling, since proposed labels (EPA Reg. No. 100-1178, EPA 

Reg. No. 100-1324) indicate that propiconazole application is to be during non-flooded period, no 

aquatic modeling was needed. Application dates for the proposed uses were based on information 

from the proposed labels (EPA Reg. Nos. 100-617, 100-1178, 100-1 312. 100-1 324). 

Please note that the surface EDWCs reproduced from the previous 2006 OWA modeling o n turf 

are higher than those generated by the currently used model. This difference could be attributed to 

the use of different input parameters. In the 2006 OW A, The default PC/\ of 0.87 was used vs. 

0.45 (the highest state PCA val ue for turf). In addition, in the 2006 OW A, Spray Drift Fraction 

was assumed to be 0.16% vs. 0. 135% in the 20 15 modeling run. 

4 
Appendix I 

SWCC Model 

PA Turf 

Table 1. Estimated Environmental Concentrations (ppb) for propiconazole. 

Peak (1-in-10 yr) 35.2 

4-day Avg (1-in-10 yr) 34.7 

21-day Avg (1-in-10 yr) 32.9 

60-day Avg (1-in-10 yr) 30.3 

365-day Avg (1-in-10 yr) 18.6 

Entire Simulation Mean 14.4 

Table 2. Summary of Model Inputs for propiconazole. 

Scenario PAturfSTD 

Cropped Area Fraction 0.45 

Koc (ml/g) 648 

Water Half-Life (days) @ 25 °C 138.4 

Benthic Half-Life (days) @ 25 °C 363 

Photolysis Half-Life {days) @ 40 °Lat 0 

Hydrolysis Half-Life (days) 0 

Soil Half-Life (days) @ 22 °C 69.2 

Foliar Half-Life {days) 35 

Molecular Wt 342.33 

Vapor Pressure (torr) 1E-6 

Solubility (mg/I) 100 

5 
Table 3. Application Schedule for propiconazole. 

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift 

4/1 Foliar 2 0.95 0.135 

4/15 Foliar 2 0.95 0.135 

4/29 Foliar 2 0.95 0.135 

5/13 Foliar 2 0.95 0.135 

PRZM GW Model 

Table 1. Groundw ater Results for Propiconazole Turf and the Wisconsin Corn - WI Central Sands 

Scenario. 

Peak Concentration (ppb) 

Post-Breakthrough Mean 

Concentration (ppb} 

Entire Simulation Mean 

Concentration {ppb) 

Average Breakthrough Time 

(days) 

Throughputs 

37.9 

35.1 

26.4 

10455.14 

3.458776 

Table 2. Chemical Properties for Groundwater Modeling of Propiconazole Turf. 

Koc (ml/g) 604 

Surface Soil Half Life (days) 53 

Hydrolysis Half Life (days) 0 

Diffusion Coefficint Air (cm2/day) 0.0 

Henry's Constant 0.0 

Enthalpy (kcal/mol) 0.0 

6 
Table 3. Pesticide application scheme used for Propiconazole Turf. This application scheme was 

applied every year of the simulation. 

Application Date Application Method Application Rate 

(Month/Day) (kg/ha) 

4/1 Above canopy application 0.88 

4/15 Above canopy application 0.88 

4/29 Above canopy application 0.88 

5/13 Above canopy application 0.88 

5/27 Above canopy application 0.88 

6/11 Above canopy application 0.88 

6/25 Above canopy application 0.88 

7/9 Above canopy application 0.88 

7