1 OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

July 9 , 2013

PC Code: 036602

MEMORANDUM DP Barcode: 409108 & 409109

SUBJECT : Mandipropamid : Drinking Water Exposure Assessment for P roposed Section 3

New Use s on: Basil, Gins eng and Succulent Bean s ; and Ex pand ed U ses on Bulb Vegetables, C ucurbits, G rapes, and F ruiting V egetabl es including T omato es

.

FROM : Richard Shamblen, Biologist

ERB2 /EFED (7507P)

THROUGH : Greg Orrick

, Environmental Scientist

Brian Anderson

, Branch Chief

ERB2 /EFED (7507P)

TO: Dennis McNeilly , Risk Assessor

Christina S wartz , Branch Chief

RAB 2 /HED (7509P)

Tony Kish , Risk Manager, RM Team 20 Rosemary Kearns, Risk Manager Review er Laura Nollen, Biologist, RIMU ERB/RD FB/RD (7505P)

T he Environmental Fate and Effects Division (EFED ) co nducted a Tier 1 d rinking w ater

exposure a ssessment for the fungicide mandipropamid . The registrant seeks a Section 3 new u se registration for b asil, g inseng and succulent b ean s ; and ex pansion of currently regist ered use groups including bulb vegetables, cucurbits, grapes, and fruiting vegetables including tomatoes. Previous exposure assessments evaluated maximum single application rates of 0.13 l bs a.i./A, four times per season. T he registrant seeks to increase the total annual application rate to 2.08 lbs

a.i./ A for tomato and basil by allowing for up to four crop production seasons per year . This proposed multi

- season total annual application r ate exceeds those assessed in previous drinking

water exposure assessments.

Tier 1 exposure m odel re sults are summarized in Table 1

. PRZM

- GW was used to

estimate mandipropamid exposure in ground water. Maximum estimated drinking water

concentrations ( EDWC ) in ground water are 87 and 79 μ g /L for acute and chronic exposures, respectively. These values are as much as 480 times higher than SCI

- GROW model results.

Maximum acute and chronic EDWCs in surface waters are 7 9 and 9

. 0 μg/L , respectively

.2

Table 1. Tier 1 Estimated Drinking Water Concentrations (EDWC) for Maximum Mandipropamid

Use Pattern s

. Drinking Water Source (Model , Version ) PCA (%) Crop Use Pattern (Maximum Annual Rate) Acute (μg/L) Chronic

(μg/L)

Su rface W ater (FIRST

, 1.1.1 ) 91 Tomato & Basil (2.08 lbs a.i./A) 7 9 9.0

Ground W ater (PRZM

- GW

, 1.01 ) N/A Tomato & Basil ( 2.08 lbs a.i./ A ) 87 79

Ground W ater (SCI

- GROW

, 2.3 ) N/A Tomato & Basil (2.08 lbs a.i./A) 0.18

Abbreviations: A= acre; a.i. = active ingredient; ha = hectare; kg = kilograms ; μg = micrograms; lbs = pounds (US); N/A = not applicable

T wo p revious Tier 1 drinking water assessments of mandipropamid produced nearly identical exposure estimates ( USEPA, 2007 ; and

, 2011). Results of multiple FIRST (v.1.1.0)

model scenarios indicat ed EDWCs in surface water s rang ing from 7 to 36 μg/L for chronic and

acute exposures. G round water ex posure estimates in both assessments were about 2.4 μg/L when calculated by SCI

- GROW (v. 2.3)

. PRZM

- GW (v. 1.01) was not used.

Differences between the previous two and current drinking water exposure assessment s reveal that ground water exposure concentrations decreased by more than a factor of 13, whereas

a cute surface water exposure concentrations nearly doubled

. These differences are likely

attrib uted to a variety of recent changes incorporated into the drinking water assessment. In particular, the following factors adopted for this risk assessment may account for the differences : 1) F our seasons per year a re assumed for tomato and basil, whereas onl y one season per

year was a ssumed for previously assessed use sites 1 ; 2) Changes to EFED model input parameter guid ance , version 2.1 ( USEPA, 2009); 3) Higher K OC model input adjustments : mean ( 575 L/kg ) used instead of lowest (405 L/kg ); 4) Lower a erobic soil metabolism model input values : 13 3 d instead of 81.3 d ; 5) Total Residue modeling approach (USEPA, 2013) was used to calculate a erobic aquatic

metabolism input of 108 days instead of separately modeling a range of half

- lives of 19 to 1323 days for parent and degradates ; 6) Percent Cropped Area ( PCA ) factor of 0.91 used instead of 0.87 (USEPA, 2012 a ) ; and, 7) R evisions to the PestDF kinetics softwa re used to calculate half

- lives.

The Total R esidue (TR) modeling approach (USEPA, 2013) was used to estimate aerobic aquatic half

- lives, and estimate drinking water concentrations in surface waters. Previous drinking water assessments calculated separate half

- lives for the parent compound and two degra da tes of concern , for which exposure was estimated with separate model runs . Simple addition of the exposure estimates for mandipropamid and it’s degradates of concern was used to generate estimated drinking water concentrations. Previous authors acknowledge this approach is conservative because the exposu re estimates may not be temporally coincident. The TR method

, however, tallies the parent compound and it’s degradates of concern prior to calculating a Total

Residue half

- life using PestDF

.

1 e

- Mail communications from Tammy Tyler of Syngenta to Johannes Corley of IR

- 4, February 31, 2013.3

1. Use Characterization

Mandipropamid is a fungicide used to contr ol downy mildew, phytophthora blight and root rot, blue mold, and late blight in vegetable production

. The fungicide can be applied as a

post

- emergent, foliar spray using ground, aerial, or chemigation 2 equipment. The proposed label specifies a maximum sea sonal application rate of 0.52 lbs. active ingredient per acre (a.i./A) , and

is divided into four separate applications of 0.13 lbs. a.i./A with a 7

- day minimum interval

.

The proposed ex pa nded 3 and new use patterns are summarized in Table 2

. For six (6 ) of the eight (8 ) proposed new and ex pa nded crop uses, the maximum application rate per event and season remain consistent with previously assessed application rates (USEPA, 2007; and, USEPA, 2011 ). T he registrant proposes , however, to expand the product a pplication to to mato
and basil with up to four (4) crop production seasons per calendar year. Thus, the registrant proposes a total of sixteen (16) application events for a cumulative annual application rate of

2.08 lbs a.i./A 4

.

Table 2 . Proposed Use Patterns for Mandipropamid

Registration

Status Use Site Maximum Application

Rate 1)
(lbs a.i./A) Maximum

Number of Application s

per Season Minimum

Application

Interval 2) (days) Maximum

Annual Application

Rate 3)
(lbs a.i./A) Maximum

Number of Application s per Year 3)

Proposed

New

Use Bean ( succulent ) ; Ginseng 0.13 4 7 0.52 4

Basil (fresh and dried) 0.13 4 7 2.08 16

Proposed

Ex pa nded

Use Bulb Vegetables; Cucurbits; Fruiting Vegetable (except tomato) ; Grapes 0.13 4 7 0.52 4

Tomato 0.13 4 7 2.08 16

Abbreviations: A= acre; a.i. = active ingredient; lbs = pounds

Note(s): 1) Single application event. 2) Minimum number of days between application events. 3) Year is defined as a calendar year; January 1 through December 31.

The proposed label covers thirteen (13) use sites . There are no requested use changes for five (5) crops or crop groups : brassica; hops ; leafy vegetables; potatoes and other tuberous and

corm vegetables ; and tobacco. The registrant seeks n ew u se registration s for mandipropamid on

the three (3) following crops and crop groups

, including hybrids and varieties thereof : 1. Basil : (fresh and dried);

2 Pesticide application through irrigation systems.

3 Additional crops, varieties or hybrids within a currently registered crop group.

4 e

- Mail communications from Tammy Tyler of Syngenta to Johannes Corley of IR

- 4, February 3 1, 2013.4

2. Bean (succulent subgroup) : Cicer arietinum (chickpea, garbanzo bean); Lupinus spp. (inkling sweet lupine, white sweet lupine, white lupine, and grain lupine). Phaseoulus

spp. (including kidney bean, lima bean, mung bean, navy bean, pinto bean, snap bean, and waxbean); Vicia faba (broad bean, fava bean); Vigna spp. (including asparagus bean, black

- eyed pea and cowpea); in succulent form only; and,

3. Ginseng

.

The registrant seeks to ex pa nd the current registration of mandipropamid on the following five (5) crop s and crop groups

, including hybrids and varieties thereof : 1. Bulb vegetables including cultivars, varieties, and/or hybrids of these and others in

 the onion (dry) subgroup 3

- 07A: daylily; fr i tillaria; garlic; garlic (great

- headed); garlic (serpent); lily onion; onion (Chinese); onion (pearl); onion (potato); shallot;

and

,

 the green onion (subgroup 3

- 07 B): chive; chive (Chinese); elegans hosta; fritillaria; kurrat; lady’s leek; leek; leek (wild); onion Beltsville bunching); onion (fresh); onion (green); onion (macrostem); onion (tree tops); onion (Welsh); and shallot;

2. Cucurbit vegetables: Chayote (fruit ); Chinese wax gourd (Chinese preserving melon); citron melon; cucumber; gherkin; gourds, edible (includes hyotan, cucuzza, hechima, Chinese okra); Momordica spp. (i ncludes balsam apple, balsam pear, bitter melon, Chinese cucumber); muskmelon (includes tru e cantaloupe, cantaloupe, casaba, crenshaw melon, golden pershaw, melon, honeydew melon, honey balls, mango melon, Persian melon, pineapple melon, Santa Claus melon, and snake melon); pumpkin; squash, summer (includes crookneck squash, scallop squash, stra intneck squash, vegetable marrow, zucchini) ; squash, winter (includes butternut squash, calabaza, hubbard squash, acorn squash, spaghetti squash); watermelon.

3. Grapes including cultivars, varieties, and/or hybrids of subgroup 13

- 07F (except fuzzy kiwifrui t): Amur river grape, gooseberry, grape, kiwifruit (hardy); maypop; schisandra berry ; 4. Fruiting Vegetable Group (except tomatoes) including cultivars, varieties, and/or hybrids of these and others in this group: African eggplant, bell pepper; cocona; eggpl ant, garden huckleberry; goji berry; groundcherry; martynia; naranjilla; okra; pea eggplant; pepino; nonbell pepper; roselle; scarlet eggplant; sunberry ; and,

5. Tomato (includes tomato, bush; tomato, currant; tomatillo; tomato tree).

2. Environmental Fate Characterization

When Mandipropamid is released into the environment, it is expected to be somewhat persistent and ha s low to moderate mobility. T he primary degradation route is typically expected

to be metabolism with half

- lives ranging from approximate ly 40 to 90 days in aerobic conditions in water and soil laboratory studies. Half

- lives from field studies were similar and ranged from 75 to 100 days. The fungicide degrades relatively quickly via photolysis with a half

- life of approximately 2 days . H ow ever, photolysis is only relevant under some environmental conditions and field studies suggest that it is not a major degradation route under conditions of those studies. Mandipropamid degrades very slowl y via hydrolysis, and volatilization from soil

and water is expected to be minimal. Bioconcentration is also not a primary concern.5

For general characterization and pesticide exposure modeling purposes, Table 3 contains selected physical and chemical properties and environmental fate data, and correspo nding sources of data for mandipropami d.

There are several data uncertainties from pesticide metabolism and mobility studies used

in this drinking water assessment, includ ing :

1. There is no statistically significant degradation of mandipropamid by hydrolysis at the p = 0.05 confidence level. Based on the level of uncertainty in the hydrolysis study due to background variability, the degradation might be as fast as 1900 d ay at pH 7 and not be detected in the current 30 d ay study. In order to bound th e effects of hydrolytic degradation in the PRZM

- GW simulations, estimates were made using the

1900 d ay hydrolysis half

- life rather than assuming no hydrolytic degradation and the

EDWC decreased from 90 to 7 9 d ay (1 2 %).

2. Of the three aerobic aquatic metabol ism studies, only one study ( MRID 46800031) is currently classified a s “supplemental and upgradeable. ” A dditional information is

needed related to identification of all major transformation products for both systems. The remaining two studies are classified “ unacceptable. ”

3. There are two batch equilibrium studies that are classified as “ supplemental and upgradeable. ” One study (MRID 46800038) include s four foreign soils , for which taxonomic classifications are needed to clarify if they represent do mestic agricultural

use a reas where the pesticide is anticipated to be applied. For this assessment, it is

assumed th at t h ree U.S. soils from one study (MRID 46800040) are representative of agricultural use areas. Although the USEPA guideline requires five soil types (USEPA, 2008 b )

, data from the three domestic soil s were used for modeling

purposes , pursuant to model input parameter guidelines, in the absence of additional acceptable data

.

4. There are f

ive aerobic soil metabolism studi es representing seven soils, yet only one study (MRID 46800020) with one soil type is currently acceptable. This is because the acceptable soil is domestic and the other six are foreign soils without taxonomic classifications with which to assess their rep resentativeness of agricultural areas where the pesticide will be applied. Although the U SEPA guideline requires four soil types for determination of transformation rates (USEPA, 2008 c ), the one soil type

was used for modeling purposes , pursuant to model input parameter guidelines, in the absence of additional acceptable data.

Reported h alf

- life values for aerobic soil and aquatic metabolism studies were calculated using the PestDF (version 2.14.1) software from referenced study data ( PestDF model results and

metabolism calculations are attached in Appendix B ).6

Table 3

. Chemical Properties and Environmental Fate Parameters of Mandipropamid

Parameter (units) Value Reference (MRID)

Selected Physical/Chemical Parameters

Molecular Mass (Empirical Formula) 411.9 g/mol (C 23 H 22 ClNO 4 ) 46800004

Vapor pressure (25 °C) 1 ) (mmHg ) < 7.1 x10

- 9 46800006

Aqueous solubility (25  C) (mg/L) 4.2 46800006

Henry’s Law Constant : calculated (25 °C) ( atm

- m 3 /mol ) <9.1 x 1 0

- 12 46800006

Log octanol

- to

- water partition

coefficient (25  C) ( log K OW ) 3.2 46800006

Dissociation constants (pKa, pKb) No pKa was found in the range of 1.0 to 12.0 by spectrophotometric titration. 46800006

Persistence

Hydrolysis

half

- life (25  C) (days) (pH 4, 7 and 9) no significa nt degradation (pH 5) 1900 (pH 7) 1000 (pH 9) 4 680000 7

Aqueous photolysis

half

- life (25  C) (days) 1.9 46800009

Aerobic soil metabolism

half

- life (25° C) (days) (Soil T exture ) 44 (Sandy loam) 46800020

Aerobic aquatic metabolism

half

- life (25°C) (days) ( Aquatic s ample system : Sediment ) 79 ( Swiss Lake : Loamy Sand )

94 ( Calwich Abbey : Silt Loam ) 4680003 1

Mobility

Freundlich organic carbon

- normalized coefficient (K FOC ) 2 )
(mL /g

oc ) (Soil T exture ) 694 (Sandy loam)

46900040 406 ( L oam y Sand )

625 ( L oam y Sand )

Field Dissipation

Terrestrial f

ield d issipation

half

- life 3) (days) (S oil T exture) 75 (Sandy loam) 46800045

100 ( L oam y sand ) 46800046

82 ( L oam y sand ) 46800047

Fish Bioconcentration7 Parameter (units) Value Reference (MRID)

Fish bioconcentration factors (steady

- state, total residues) (L/kg) Depuration Rate: Edible: 8.8

- 10

Inedible: 160

- 190 Whole body: 35

- 48 x Depuration: >82% in 25 hours 46800109

Abbreviations: atm = atmosphere; °C = degree Celsius; g= gram; Hg = mercury; L = liter; log = logarithm , base 10 ;

m 3 = cubic meter; mg = milligram; mL = milliliter; mm = millimeter; mol = mole; NA = Not applicable ; MRID =

master record identification

Note(s): 1) Converted to torr (mmHg) from Pascal units (Pa). 2) The coefficient of variation (CV) for K FO C (0.3 ) is less than the CV of K d ( 0.5 ), thus s orption was correlated with organic carbon content. K FOC w a s calculated with the following equation: (K F / % organic matter)*100 (USEPA, 2008 b ). Calculations are provided in the Adsorption/ Desorption spreadsheet attached in Appendix B

. 3) Field dissipation data are not used for modeling purposes in the Tier 1 drinking water assessment. Thus,

half

- lives were not re

- calculated.

3

. Drinking Water Exposure Model ing

3.1 Model Parameterization

3.1.1 FIRST (Version 1.1.1)

EFED used the FQPA 5 Index Reservoir Screening Tool (FIRST) Version 1.1.1 (USEPA,

2008 a ) to calculate Tier 1 estimate d drinking water concentrations (EDWC) for surface water

s ystem s

. The model is used to estimate both acute and chronic potential concentration s in untreated drinking water (USEPA, 2001 a ). Model i nput parameters (USEPA, 2001a)

, values selected, brief justification statement s for values selected (USEPA, 2009), and data sources are summarized below in Table 4

.

T otal Residue (TR) kinetics calculations were used to estimate the aero bic aquatic

metabolism half

- life model input value (US EPA, 2013). TR kinetics calculations are presented in Appendix B. Total residue s include th e mandipropamid parent compound and its major degradates of concern

, SYN500003 and SYN 504851. Other model inputs did not require TR calculations because the degradates of concern were not present in the supporting studies at

concentrations greater than 10% of the applied

.

5 FQPA pertains to the Food Quality Protection Act of 1996.8

Table 4. FIRST (v1.1.1) Input Parameter s

Paramete r Value Justification Reference (MRID)

Application Rate (lbs a.i./ A) 0.13 Maximum application rate Proposed label

Application Events (per year) 1 6 Maximum number of applications per

year Proposed label Meeting Minutes

Minimum A pplication

I nterval (days) 7 Minimum application interval Proposed label

Application Method Aerial Application equipment of maximum

exposure Proposed label

Incorporation D epth (cm) 0 Product is foliar applied via ground or

aerial spray Proposed label

Wetted

- in No Not applicable US EPA, 200 9

Solubility (25  C) (mg/L) 4.2 M aximum value at

20

- 25  C 46800006

Hydrolysis

Half

- life (days) 190 0 Represents the study value at pH 7. 4680007;

46800008

Aquatic Photolysis

Half

- life (days) 1.9 Represents the maximum study value

. 46800009

Aerobic Aquatic

Metabolism

Half

- life (days) 108 Total Residue approach was used to

calculate half

- lives.

Represents the upper 90 th percentile

confidence bound on the mean of two
total residue half

- lives

. 4680003 1

Organic Carbon Partition

Coefficient (K OC ) (mL /kg OC ) 57 5 Represents the m ean of three values

. 46800040

Aerobic Soil Metabolism

Half

- lif e (days) 133 Represents 3x the single acceptable

value

. 4680002 0

P ercent C ropped A rea (PCA) Adjustment Factor ( decimal ) 0. 91 N ational

- level PCA for all agricultural

land US EPA, 2012 a

Abbreviations: A= acre; a.i. = active ingredient; cm = centimeter; kg = kilogram; L = liter; lbs. = pounds; mg = milligram; mL = milliliter ; MRID = master record identification

3.1.2 SCI

- GROW (Version 2.3)

T he Screening Concentration in Ground Water ( SCI

- GROW version 2.3 ) model was used

to estimate drinking water pesticide concentrations in ground water. Results of the Tier 1 model9

determine if mandipropamid potentially po s e s sufficient risk to warran t higher level assessment (USEPA, 2001 b ). Table 5 summarizes the SCI

- GROW input parameters (USEPA, 2001 b ), justification for values selected (USEPA, 2009), and appropriate references and data sources (US EPA, 2001 b ; and, USEPA, 2009).

Table 5 . SCI

- GROW (Version 2.3) Input Parameters

Parameter Value Justification Reference (MRID)

Application Rate (lbs a.i./ A) 0.13 Maximum application rate Proposed label

Application Events (per year) 16 Maximum number of applications

per year Proposed label Meeting Minutes

Organic Carbon Partition

Coefficient (K OC ) ( m L/kg OC ) 625 Median of three K OC value s ; less than three

- fold variation 46800040

Aerobic Soil Metabolism

Half

- life (days) 4 4 Single acceptable aerobic soil

metabolism value 46800020

Abbreviations: A= acre; a.i. = active ingredient; cm = centimeters; kg = kilogram; L = liter; mg = milligrams ; mL =

milliliter ; MRID = master record identification

3.1.3 PRZM

- GW (Version 1.01)

As part of a one

- year evaluation period, EFED scientists are using the Pesticide Root Zone Model for Ground Water (PRZM

- GW v. 1.01) model in conjunction with SCI

- GROW to

estimate Tier 1 pesticide concentrations in ground water used as drinking water ( USEPA,

2012 d )

. PRZM

- GW input parameters are summarized below in Table 6

.

A cumulative annual application rate of 2.3 3 kg a.i./ ha (2.08 lbs a.i./ A) was used in

PRZM

- GW . This rate represent s the registrant’s proposed most conservative use pattern ( i

. e

. four (4) crop production seasons per calendar year for use on both tomatoes a nd basil).

PRZM

- GW v.1.01 is limited to eleven (11) pesticide application events per year. In order to model 16 application events using 11 input events

, v a lues for the following input parameters

were adjusted : 1) single

- event maximum application rate; 2) number of application events per

year; and , 3) application interval , 4) number of years to simulate

.

T he single

- event maximum application rate was increased from 0.14 7 kg a.i./ ha (0.13 lbs a.i./A) to 0.21 2 kg a.i. / ha (0.19 lbs a.i./ A). C orresponding ly, the number of annual applicati on events decreased fro m sixteen (16) to eleven (11). Moreover, the application interval was equally distributed across the calendar year. This increased the proposed label’s minimum application interval from 7 to 33 days

. The cumulative annual application rate of 2.3 3 kg a.i. / ha (2.08 lbs a.i./A)

, however, remains consistent with the registrant’s proposed label product application

scenario. Because PRZM

- GW is limited to 800 total application events, the extended simulati on was conducted every year through year 72.10

An analysis was performed on the effects of adjust ing PRZM

- GW input para meters

. Results indicate no difference as a result of using higher single

- event application rates, reduced

number s of applications per yea r, and increased application interval s with respect to those of the proposed product label

.

Table 6 . PRZM

- GW (Version 1.01 ) Input Parameters

Parameter Value Justification Source

Application Rate 1 ) (kg a.i./ ha) 0. 212
See text above table. Maximum

annual application rate is divided into 11 application events spread across

the year. Proposed Label

Application Events (per year) 1 1 Proposed Label

Application interval (days) 33 Proposed Label

Application Metho d 2 1) Proposed use pattern. 2) Above canopy selected : product is

a ppli ed to target foliage. Proposed Label USEPA, 2012 c

Initial Application

D ate 2&3 ) February 2 1) Proposed f our crop production

seasons during the calendar year

. 2) Eleven (11) application events evenly distributed

. 3) Sensitivity analysis (see text above table) USEPA, 2012 c

Hydrolysis

Half

- life (days) 1900 Represents the study value at pH 7. 46800007

Aerobic Soil Metabolism

Half

- life (25  C) (days) 133 Represents 3x the single acceptable

half

- life at 25°C

. 46800020

Organic Carbon Partition Coefficient (K OC ) ( ml/ g OC ) 5 75 Represents the mean of three

K OC values 46800040

Abbreviations: A= acre; a.i. = active ingredient; cm = centimet ers; ha = hectare; k g = kilo grams; ml = milliliter ;  C = degree Celsius

Note(s): 1) Unlike the other two models used in this d rinking water assessment, the pesticide appli cation rate for

PRZM

- GW requires metric units. 2) The initial application date selected represents eleven (11) evenly distributed application dates ( i.e. approximately every 33 days) duri ng the calendar year , beginning February 2

. 3) Calendar dates are set to “Absolute.”

3.2 Model Results

R esults of the three models used in this drinking water assessment are summarized in

Table 1

. FIRST model estimated drinking water concentrations ( EDWCs ) we re 79 μg/L for acute exposure and 9.0 μg/L for chronic exposure. The SCI

- GROW EDWC was 0.18 μg/L.

PRZM

- GW EDWCs are tabulated in Table 7

.11

For the PROZM

- GW model, a ll six geographic scenarios were model ed as surrogates for tomato and basil crops

. The Wisconsin corn scenario provi ded the most conservative estimate s for acute and chronic drinking water exposure concentrations

, at 87 and 7 9 μg/L , respectively

.

Table 7 . PRZM

- GW E stimated D rinking W ater C oncentration s and Average Breakthrough Time

for Mand ipropamid Use Scenarios 1)

.

Crop Scenario Max imum Daily

Concentration

- Acute

- (μg/L) Ave rage

Breakthrough

Time (y ea rs) Post

- breakthrough

Average

- Chronic

- (μg/L)

Tomato DMV corn 47 14 40

Tomato FL citrus 57 14 5 2

Tomato FL potato 2) 0.1 4 34 0.0 8

Tomato GA peanut 2) 1 1 28 1 0

Tomato NC cotton 3 1 16 26

Tomato WI corn 2) 87 28 79

Abbreviations: μg = micro grams ; L = liter

Note(s): 1) PRZM

- GW model results are reported to two (2) significant figures. 2) The PRZM

- GW extended weather files were created and used for these scenarios.12

Figure 1 : PRZM

- GW WI Corn Extended Weather Scenario

Uncertainty regarding PRZM

- GW outputs results from the extended time period of ground water flow and the model’s underlying assumptions, including that soils are sterile below

a 1

- meter depth. Bacteria in soils greater than one meter below the surface may degrade the residues of concern (ROC), however potentially at a slower rate than in the surface layer, and may potentiate over years or decades in order to degrade the ROC at a faster rate. Mandipropamid residues of concern have an average breakthrough ti me of 28 years with the Wisconsin scenario. Breakthrough times for PRZM

- GW have been up to one order of magnitude shorter than observed for bromide (USEPA, 2012 e ) and up to one order of magnitude longer than observed for oxamyl (MRID 45591605).

Also, the model represents a drinking water well that is surrounded by a large pesticide

treated area. Most drinking water wells are not surrounded by large pesticide

- treated areas. Therefore, horizontal convection and dispersion may attenuate persistent, dissolved residues such

as these over time.13

References

MRID 45591605. Hiscock, A., R. Warren, and B. Patterson. A Small

- Scale Prospective Groundwater Monitoring Study for Oxamyl. DuPont Report No. AMR 4318

- 97. Unpublished study conducted by Stone Environmental, Inc., Ecologic, Inc., Agricultural Systems Associates, AGVISE Laboratories, Centre Analytical Laboratories, Inc., and E.I. du Pont de Nemours and Company; submitted by E.I. du Pont de Nemours and Company, Wilmington, DE. Jan. 14, 2002.

USEPA, 2001 a

. FIR ST User’s Manual: FQPA Index Reserovir Screening Tool . U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and

Effects Division. August 1, 2001.

USEPA, 2001 b

. SCI

- GROW Screening Concentration In Ground Water: User Manua l. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and

Effects Division. November 1, 2001.

USEPA. 200 6

. Guidance for Developing a Tier 1 Drinking Water Exposure Assessment. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fa te and

Effects Division. Jan. 27 , 200 6

.

USEPA. 200 7

. Drinking water assessment for mandipro p amid and its two degradates (SYN500003, SYN504851) use on brassica vegetables, bulb vegetables, cucurbits, fruiting vegetables, grapes, leafy vegetables, potatoes, tomatoes, tuberous and corn vegetables

. DP barcode D339258

. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division.

Memorandum to the Health Effects Division. April 23 , 200 7

.

USEPA, 2008 a

. FIRST FQPA Index Reservoir Screening Tool

, Version 1.1.1. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division. March 25, 2008.

USEPA. 2008 b

. Fate, Transport and Transformation Test Guidelines : OPPTS 835.1230 Adsorption/ Desorption (Batch Equilibrium)

, U.S. Environmen tal Protection Agency, Office of Prevention, Pesticides, and Toxic Substances (7101), Environmental Fate and

Effects Division. EPA 712

- C

- 08

- 009, October, 2008.

USEPA. 2008 c

. Fate, Transport and Transformation Test Guidelines: OPPTS 835.4100 Aerobic

Soil Metabolism; and, OPPTS 835.4200 Anaerobic Soil Metabolism

, U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances (7101),

Environmental Fate and Effects Division. EPA 712

- C

- 08

- 016, EPA 712

- C

- 08

- 017, October, 2008.

USE PA. 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides ; version 2.1

. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects Division. Oct. 22, 2009.14

USEPA. 2011. Mandipropamid: Drinking Water Exposure Assessmnt of Section 3 new Use for
Outdoor; Non

-

food Crops. DP barcode D383758. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects Division.

Memorandum to the Registration. Division. March 2, 2011.

USEPA. 2012 a

. Guidance on Development and Use of Percent Cropped Area and Percent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update.

Internal Environmental Fate and Effects Divisi on memorandum. U.S. Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention. Mar. 16, 2012.

USEPA. 2012 b

. Guidance for Using PRZM

- GW in Drinking Water Exposure Assessments. U.S. Environmental Protection Agency, Office of Pesti cide Programs, Environm ental Fate and

Effects Division . Oct. 15, 2012.

USEPA. 2012 c

. Guidance for Selecting Input Parameters for Modeling Pesticide Concentrations in Groundwater Using the Pesticide Root Zone Model

. Version 1.0 . U.S.

Environmental Protect ion Agency, Office of Pesticide Programs, Environm ental Fate and Effects Division; and, Health Canada, Pesticide Management Regulatory Agency, Environmental Assessment Directorate. Oct. 15, 2012.

USEPA. 2012 d

. Approval of PRZM

- GW for Use in Drinking Water Exposure Assessments . U.S. Environmental Protection Agency, Office of Pesticide Programs, Environm ental Fate and

Effects Division

, Memorandum to the Environmental Fate and Effects Division

. Dec. 11

, 2012.

USEPA. 2012 e

. Identification and Evaluation of Existing Models for Estimating Environmental Pesticide Transport to Groundwater. Final Report (Draft). U.S. Environmental Protection Agency ; Health Canada. Jan. 27 , 2012.

USEPA. 2013. Guidance for Modeling Pesticides Total Toxic Residues (TTR)

- DRAFT : v.01. U.S. Environmental Protection Agency, Office of Pesticide Programs, Environmental

Fate and Effects Division. January 3, 2013.15

Appendix A. Exposure Model Input/Output Files

FIRST and SCI

- GROW O utput F iles, with input values embedded in the O utput F iles.

PRZM

- GW Input Files

Appendix B. Calculations

Aerobic Aquatic Metabolism Total Residue:

Aerobic Soil Metabolism with R model degradation kinetics:

Soil Adsorption/ Desorption: