1

MEMORANDUM

DATE: April 04, 2013

SUBJECT: Addendum of Drinking Water Exposure Assessment for the Section 3 New Use of 

Pyraclostrobin on Various Agricultural Crops and Residential Ornamentals

TO: Andrew Ertman, Risk Manager Reviewer

Barbara Madden, Product Manager

Registration Division (7505P)

FROM: Faruque Khan, Ph.D. Senior Fate Scientist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

APPROVED

BY: Edward Odenkirchen, Ph.D, Acting Branch Chief

Sujatha Sankula, Ph.D. Lead Biologist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

Executive Summary

This is an addendum to the earlier memorandum related to drinking water exposure assessment 

issued on February 13, 2013. This revised memorandum reflects recently withdrawn cranberry

use by the registrant. In addition, exposure of pyraclostrobin in ground water was evaluated with 

the PRZM-GW model as well as recent published pyraclostrobin monitoring data were 

summarized in this memorandum. The estimated drinking water concentrations (EDWCs) of 

pyraclostrobin ( carbamic acid, [2-[[[1-(4-chlorophenyl)-1H-pyrazol-3-yl[oxy]methyl]phenyl 

methoxy-,methyl ester]) in surface water and ground water in support of the proposed Section 3 

new use of pyraclostrobin for control of a variety of fungi on several use sites were summarized

below. 

The Interregional Research Project Number 4 is seeking registration of several new uses 

(described in Table 1) of pyraclostrobin on one supplemental label for Cabrio®Fungicide and 

one supplemental label Headline®Fungicide as well as four supplemental labels for Pristine®

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

PC Code: 099100

DP Barcodes: D403871, D405066
2

Fungicide. Summary of directions for the proposed uses of pyraclostrobin were provided in 

Table 1. 

Some of the proposed end use products contain two active ingredients pyraclostrobin and 

boscalid. However, this assessment focuses only on the active ingredient pyraclostrobin. No 

degradates of pyraclostrobin were included in the drinking water assessment based on the 

recommendation from the Metabolism Assessment Review Committee (MARC) of Health

Effects Division (USEPA 2001, D278044). The EDWCs for both surface and ground water 

recommended for use in HED’s human health dietary risk assessment are summarized in Table 

2. Estimated pyraclostrobin concentrations in surface water and ground water used for drinking 

water are summarized in Table 6. 

For the proposed use of pyraclostrobin in fruiting vegetables resulted in the highest surface water 

concentrations of at 16.6 μg/L for 1-10 year peak value from ground application and 1-10 annual 

year average of 1.1 μg/L from aerial application. The acute and chronic EDWCs resulting from 

the proposed application uses are lower than the EDWCs for surface water in the previously

recommended drinking water assessments for pyraclostrobin for turf uses (USEPA 2007 

D389729+). Since the EDWCs for surface water for proposed uses are lower than the previously

recommended EDWCs for this chemical, the EDWCs for surface water will not supersede the 

EDWCs previously recommended for turf use. The Percent Cropped Area of 1.0 was assumed as 

pyraclostrobin has uses on ornamentals, turf, and a variety of agricultural crops. Revised EDWCs 

in groundwater superseded the EDWCs previously recommended for turf use. Recent monitoring 

data show pyraclostrobin detection of a maximum of 23.9 ng/L in surface water and a maximum 

of 4.8ng/L groundwater samples (Reilly et al., 2012).

Table 1. Proposed New Uses and Conversion of Old Crop Groups to New Crop Groups for 

Pyraclostrobin

Use Site

Single App. 

Rate

(lbs. ai/A)a

# of 

App

Seasonal 

App. Rate

(lbs. ai/A)

Retreat

ment 

Interval 

(days)

PHI App. 

Typeb

Geographic 

Restrictions

EPA Reg # 

Comments

Proposed New Uses –

Artichoke

(Globe) 0.15– 0.18 3 0.55 7-14 0 A,G,S None

7969-199

Begin app. At the initiation of the 

protection phase when approximately 

25% of the plants have bolted.

Belgium Endive 0.8 to 1.6 oz. per 1000 lbs rootsc

7969-199

Application made to roots when 

brought into cold storage and at the 

beginning of forcing.

Persimmon 0.15 – 0.18 3 0.55 7-14 0 A,G,S None Prior to onset of disease development

Sugarcane 0.15-0.2 4 0.78 14-28 14 A,G,S None 7969-289
3

Table 1. Proposed New Uses and Conversion of Old Crop Groups to New Crop Groups for 

Pyraclostrobin

Use Site

Single App. 

Rate

(lbs. ai/A)a

# of 

App

Seasonal 

App. Rate

(lbs. ai/A)

Retreat

ment 

Interval 

(days)

PHI App. 

Typeb

Geographic 

Restrictions

EPA Reg # 

Comments

Residential 

Ornamentals 0.156 6 0.93 14 0 NSd None 7969-GLG

Conversion of old crop group to new crop group 

Bulb vegetables

(Group 3-07) 0.1-0.15 6 0.9 14 7 A,G,S None 7969-199Prior to onset of disease and continue

Bushberry and 

Caneberry 

subgroup

(13-07B)

0.15– 0.18 4 0.73 7-14 0 A,G,S Not for use 

in CA

7969-199

Prior to onset of disease and continue

Citrus Fruit 

Group (10-10) 0.15 – 0.24 4 0.88 10-21 0 A,G,S None 7969-289Prior to onset of disease and continue

Fruiting 

Vegetables

Group (8-10)

0.10-0.20 6 1.2 5-14 0 A,G,S Not for use 

in CA

7969-187

Prior to onset of disease and continue

Low growing 

berry subgroup 

(includes 

cranberry)

(13-07G)

0.15 – 0.18 5 0.92 7-14 0 A,G,S None

7969-187

No later than 10% bloom or prior to 

disease development and continue

Oilseed crops

Group 20

0.10-0.20 2 0.39 7-14 21 A,G,S None

7969-289

Prior to disease development and 

continue...if conditions are conducive 

for disease development

Pome Fruit 

Groups (11-10) 0.11 – 0.15 4 0.6 7-14 0 A,G,S None

7969-187

Begin applications prior to disease 

development and continue.

Root vegetables, 

1B (except sugar 

beets)

0.06 - 0.17 6 0.52 7-14 0 AGS None

7969-199

Begin applications prior to disease 

development and continue.

Small fruit, vine 

climbing 

subgroup 13-07F

(except fuzzy 

kiwifruit)

0.10 – 0.15 6 0.9 10-21 14 A,G,S None

7969-187

Prior to onset of disease when 

conditions favor disease during early 

bloom, bunch pre-closure and veraison.

Tomato

transplants for 

homeonwers 

market4

0.1– 0.2

2 1.1 5-14 0 A,G,S None Prior to disease development and 

continue
4

Table 1. Proposed New Uses and Conversion of Old Crop Groups to New Crop Groups for 

Pyraclostrobin

Use Site

Single App. 

Rate

(lbs. ai/A)a

# of 

App

Seasonal 

App. Rate

(lbs. ai/A)

Retreat

ment 

Interval 

(days)

PHI App. 

Typeb

Geographic 

Restrictions

EPA Reg # 

Comments

Turnip greens 0.15 – 0.20 2 0.4 7-14 14 A,G,S None Prior to disease development and 

continue.

a Adopted from “Summary of Directions for the Proposed Uses of Pyraclostrobin “ provide by Registration Division (Appendix X)

b Application methods: Aerial (A), Ground (G) and Sprinkler (S)

c

Indoor use, exposure to surface water and groundwater would be low. No exposure assessment was performed

d Not Specified, assumed hand spray 

4

 Since tomato is in the fruiting vegetable cropgroup, no separate exposure assessment was performed for drinking water. 

Table 2. Recommended EDWCs for Drinking Water risk assessment for pyraclostrobin 

Use

Source of Drinking 

Water

Pyraclostrobin concentration in drinking water (μg/L)

Acute1 Non-Cancer 

Chronic1

Cancer Chronic1

Surface Water 35.6 2.3 1.5

Groundwater20.06 0.02 0.02

1 These are the highest EDWCs for previously evaluated use scenarios and the estimated acute and annual average 

surface water concentrations were 35.6 and 2.3 μg/L respectively. Previously estimated groundwater concentrations 

for acute was 0.02 μg/L 2007, D389729+. 

2 EDWCs based on PRZM-GW model

Proposed Uses

The Interregional Research Project Number 4 is seeking registration of several new uses 

(described in Table 1) of pyraclostrobin on one supplemental label for Cabrio®Fungicide and 

one supplemental label Headline®Fungicide as well as four supplemental labels for Pristine®

Fungicide.

This assessment examines potential exposure to pyraclostrobin only. Aerial, chemigation, and 

ground applications are proposed for the agricultural crops. Five of the proposed uses were 

considered as not being previously assessed in drinking water assessments. These include use on 

globe artichoke, persimmon, low growing berries, sugarcane, and ornamentals (homeowner).

Since aerial application provides higher exposure, major crops scenarios were simulated with 

aerial application. A ground application scenario was used to compare with the highest exposure 

scenario of aerial application (PA tomato STD). Resulted EDWCs for both aerial and ground are 

very comparable. Sprinkler irrigation assumed to be similar to ground application. An additional 

new use for Belgium endive was not considered in this assessment due to indoor use of 

pyraclostrobin. 
5

Residues of Concern

The Metabolism Assessment Review Committee (MARC) reported that the residue of concern 

for pyraclostrobin in drinking water is the parent only (USEPA 2001, D278044). 

Modeling Approach and Input Parameters

Models

Surface Water 

The EDWCs were generated using EFED’s standard suite of models. Pesticide Root Zone Model 

(PRZM v3.12.2, May 12, 2005) and Exposure Analysis Modeling System (EXAMS v2.98.04.06, 

Apr. 25, 2005) are simulation models coupled with the input shell PRZM/EXAMS (PE v5.0, 

Nov. 15, 2006) to generate EDWCs of pyraclostrobin residues that may occur in surface water 

for drinking water. The PRZM model simulates pesticide movement and transformation from 

crop application through soil residue processes. The EXAMS model simulates pesticide loading 

via runoff, erosion, and spray drift assuming a standard watershed of 172.8 ha that drains into an 

adjacent standard drinking water index reservoir of 5.26 ha, an average depth of 2.74 m. A more 

detailed description of the index reservoir watershed can be found in Jones et al., 1998. Standard 

percent cropped areas (PCA) were used for proposed uses as estimates of the extent of watershed 

on which crops are grown. The default PCA of 1.0 was used for the proposed uses because 

pyraclostrobin can be used in both agricultural and non-agricultural settings (USEPA 2012). 

Ground Water 

Screening Concentration in Ground Water (SCI-GROW v2.3, Jul. 29, 2003) is a regression 

model used as a screening tool to estimate pesticide concentrations found in ground water used 

as drinking water. The SCI-GROW model and user’s manual may also be downloaded from the 

EPA Water Models web-page (http://www.epa.gov/oppefed1/models/water/#scigrow). PCAs are 

not used with the SCI-GROW model.

In addition, Tier 1 groundwater EDWCs for pyraclostrobin, resulting from its use on 

various crops were also derived using the PRZM-GW model (Pesticide Root Zone Model for 

Groundwater, version 1.0, August 31, 2012), with the GW-GUI (Graphical User Interface, 

version 1.0, August 31, 2012). PRZM-GW is a one-dimensional, finite-difference model that 

estimates the concentrations of pesticides in groundwater. It accounts for pesticide fate in the 

crop root zone by simulating pesticide transport and degradation through the soil profile after a 

pesticide is applied to an agricultural field. PRZM-GW permits the assessment of multiple years 

of pesticide application (up to 100 years) on a single site. Six standard scenarios, each 

representing a different region known to be vulnerable to groundwater contaminations, are 

available for use with PRZM-GW for risk assessment purposes. In PRZM-GW simulations, each 

of these standard scenarios was used. PRZM-GW output values represent pesticide 

concentrations in a vulnerable groundwater supply that is located directly beneath a rural 

agricultural field following many years of pesticide application.
6

Input Parameters

A summary of the model input parameter values used in PRZM/EXAMS, SCI-GROW, and the 

PRZM_GW Models are in Table 3, Table 4, and Table 5 presented in respectively. Input 

parameters were selected in accordance with EFED’s “Guidance for Selecting Input Parameters 

in Modeling the Environmental Fate and Transport of Pesticides,” Version 2.1 (USEPA, 2009). 

Sample model output files are located in Appendix B.

Table 3. PRZM/EXAMS Input Parameters for Pyraclostrobin Proposed Uses 

Parameter Input Value Source Comment

Use Site

Scenario and Application 

Date

Artichoke (Globe)

 CA Row Crop RLF 

Multiple application dates

1

Label directions

See Section titled 

“Proposed Use” for 

full explanation

A combination of 

label directions and 

information related 

to crop profile in 

current scenarios 

for PRZM/EXAMS

Bulb vegetable Group (3-07)

 CA Onion STD

 Multiple application dates

Label directions

Bushberry and caneberry 

subgroup (13-07 A)

 OR Berries STD

Multiple application dates

Label directions

Low growingberry (13-07G)

 CA Strawberry STD

 FL Strawberry STD

 Multiple application dates

Label directions

Citrus Fruit Group (10-10)

 CA Citrus STD 

 FL Citrus STD 

Multiple application dates

Label directions

Fruiting Vegetable Group (8-

10)

 FL Tomato STD

 PA Tomato STD

 FL Pepper STD

Multiple application dates

Label directions

Not for use in CA

Oilseed Group (20)

 MS Cotton STD

 NC Cotton STD

 ND Canola STD

Label directions

Pome Fruit Group (11-10) 

 NC Apple STD

 OR Apple STD

 PA Apple STD

Multiple application dates

Label directions

Root vegetables 1B 

 FL Carrot

 ID Potato

 ME Potato

Multiple application dates

Label directions

(Except sugarbeet)
7

Table 3. PRZM/EXAMS Input Parameters for Pyraclostrobin Proposed Uses 

Parameter Input Value Source Comment

Small Fruit, vine climbing 

subgroup 

 CA Grape STD

 NY Grape STD

Multiple application dates

Label directions

(Except fuzzy kiwifruit)

Sugercane

 FL Sugarcane STD

 LA Sugercane

Multiple application dates

Label directions

Turnip Greens Label directions

Since the scenarios 

for turnip same as 

root vegetables and 

application rate for 

turnip is lower than 

the root vegetables 

group, no 

PRZM/EXAMS 

modeling was 

performed. 

Assumed EDWCs 

for turnip would be 

lower than the 

EDWCs for root 

vegetables 

Ornamentals (Residential)

CA Residiential RLF

CA Impervious RLF

March 1

Label provides partial 

information related to 

application. Registration 

Division (personal 

communication) provided 

application rate and 

frequency of application. 

Used similar 

approach described 

for Endengered 

Species 

Assessment

Residential 

scenario with 100% 

application rate 

Impervious 

scenario with 

1.68% of 

application rate

Post process for 

exposure2

Applications per year See Table 2 Label directions

See Section titled 

“Proposed Use” for 

full explanation

Application method

Foliar-Aerial, ground and 

sprinkler irrigation Label directions Apply to all 

proposed uses

CAM 2 Default for foliar 

application

Hydrolysis (t1/2) 0 MRID 46902201 Stable
8

Table 3. PRZM/EXAMS Input Parameters for Pyraclostrobin Proposed Uses 

Parameter Input Value Source Comment

Spray drift fraction 

Aerial: 0.16

Ground: 0.64

Sprinkler Irrigation: 

PRZM/EXAMS input 

guidance document 

Default for foliar 

application for 

drinking water 

assessment

Aerobic soil metabolism 

(t1/2)

247.2 days 

45118631

MRID 45118632

MRID 45367504

Upper 90th %-ile 

confidence bound 

on the mean of six 

half-lives3

Aerobic aquatic 

metabolism (t1/2) 45.1 days

MRID 45118637 90th%ile reported 

half-lives for 14C 

labeled 

chlorophenyl (8.4 

days) and tolyl ( 

26.4 days) rings.

Anaerobic aquatic 

metabolism (t1/2)

12.1 days MRID 45118634

90th%ile reported 

half-lives for 14C 

labeled 

chlorophenyl (191 

days) and tolyl ( 

6.91 days)rings.

Aquatic photolysis (t1/2) 0.11 days MRID 45118629

90th%ile reported 

half-lives for 14C 

labeled 

chlorophenyl (0.05 

days) and tolyl ( 

0.08) days)rings.

Vapor pressure 6.88×10--7(mmHg) --

MRID 470780-01to 

470780-08

Solubility in water 

(pH 7, 20 °C) 2.7mg/L --

Molecular weight 388 g/mole --

Henry’s Law constant 

(20 °C) 1.3×10-7

atm.m3/mol -- Estimated1

Partition coefficient Koc 9304 mL/g MRID 46808411

Average Koc (7889, 

16000, 7889, 6000, 

9000, 9436, and 

9304) 

1

= Since pyraclostrobin can be applied based on pest pressure, multiple application dates were used to simulates 

pyraclostrobin exposure in drinking water. Application dates and exposure were provided in appendix X

2

[(Residential EEC) x (0.5 amount pervious surface) x (% treated, 0.15 for woody ornamental)] + [Impervious 

Surface EEC x 0.5 amount impervious surface]

3

= http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm
9

Table 4. SCI-GROW (v2.3) Input Parameter Values for Pyraclostrobin

Parameter Value Source Comments

Application Rate (lbs 

a.i./acre)

0.184 EPA Reg # 7969-199

Proposed label Number of 

applications 5 EPA Reg # 7969-199

Koc (mL/g) 9000 MRID 46808411

Median of seven KOC values. There is 

not a three fold difference in observed 

values. 

Aerobic soil 

metabolism t 1⁄2 (days) 161

MRID 45118631

MRID 45118632

MRID 45367504

Median of four values. There was not a 

five-fold difference in values.

Table 1. Input values for the PRZM-GW model for ptraclostrobin.

Variable Name Data Value

Data Source

MRID(s) Comment

Application Method Aerial (fruiting vegetable), Proposed labels EPA Reg# 7969-187

Application Rate 

(lbs. a.i./acre) [kg/ha] 0.20 [0.22] (fruiting vegetable), Proposed labels EPA Reg# 7969-187

Application Frequency 6 times per year Proposed labels EPA Reg# 7969-187

Application Interval (days) 5 days Proposed labels EPA Reg# 7969-187

Hydrolysis t1/2 = stable 48409101 EPA Reg# 7969-187

Aerobic Soil Metabolism t1/2 = 247.2days

45118631

MRID 45118632

MRID 45367504

Upper 90th %-ile 

confidence bound on 

the mean of six halflives1

Koc 9304 mL/goc MRID 46808411

Average Koc (7889, 

16000, 7889, 6000, 

9000, 9436, and 

9304) 1

1

EFED input parameter guidance: http://www.epa.gov/oppefed1/models/water/przm_gw/wqtt_przm_gw_input_guidance.htm

Table 5. Modified Tier I Rice Model (for Estimating Exposure from Use on Cranberries) 

Input Parameters for Pyraclostrobin

Input Parameter Value Comments Source

Application rate

(lbs a.i./A) 0.88 Maximum proposed annual application rate Proposed label

Organic carbon partition 

coefficient (Koc) (L/kgOC)

9304 Represents the mean Koc value for parent 

(n=7)

MRID 46808411
10

Modeling Results

Estimated pyraclotrobin concentrations in surface water and ground water used for 

drinking water are summarized in Table 6. Estimated concentrations in surface water for use on 

fruiting vegetable resulted in the highest EDWC at 16.6 μg/L for acute from ground application 

and annual average of EDWCs from aerial application. Acute estimated pyraclotrobin

concentrations in surface water used for drinking water for other uses ranged from 1.4 to 16.6

μg/L. Estimated annual average concentrations ranged from 0.1to 0.9 μg/L. SCIGROW model 

simulated concentrations in ground water was 6.2E-03 μg/L for the highest application rate. The 

SCIGROW and PRZM-GW concentrations represent groundwater concentration that might be expected 

in shallow unconfined aquifers under sandy soils. All PRZM-GW scenarios , 3 required the use of an 

extended weather file, which allows the user to run the simulation for up to 100 years in order to observe 

breakthrough. PRZM_GW simulated groundwater concentrations are lower than SCIGROW model and 

listed in Table 7 for six vulnerable sites.

Table 6. EDWCs for Pyraclostrobin Applications to Various Crops and Home Owner 

Garden

Drinking 

Water Source Crop

Crop Scenario

1-in-10-year 

Peak Exposure 

1-in-10-year 

Annual Mean 

Exposure 

30-year Mean 

Exposure 

Concentration (μg/L)

Surface water1

Artichoke

CA Rowcrop_RLF 2.2-3.1 0.2 0.1

Berry-bush/cane

OR Berry STD 2.5-4.1 0.3-0.4 0.3

Berry-low growing

FL Strawberry STD 4.8-5.1 0.4-0.5 0.3-0.4

Bulb vegetable

CA Onion STD 1.6 0.1 0.1

Citrus

CA Citrus STD

FL Citrus STD

1.9-2.0

4.7-8.6

0.1-0.2

0.5

0.1

0.3-0.4

Fruiting vegetable

CA Tomato STD

FL Pepper STD

FL Tomato STD

PA Tomato STD

PA Tomato STD (G)2

2.0-2.7

8.7-9.1

8.8-10.9

11.3-16.2

11.2-16.6

0.3-0.4

0.8

0.8-0.9

0.8-1.1

0.8-1.0

0.2-0.3

0.6

0.7-0.6

0.7-0.9

0.6-0.8

Oilseed

MS Cotton STD

NC Cotton STD

ND Canola STD

5.8-7.6

.8-7.5

1.9-2.8

0.4-05

0.3-04

0.1

0.3

0.3

0.1

Pome Fruits

NC Apple STD

OR Apple STD

PA Apple STD

4.6-8.6

3.9-6.1

0.4-0.5

0.2-0.3

0.3-0.4

0.3

0.2

0.2

Persimmon

NC Apple STD 9.1-5.3 0.4 0.3

Root Vegetable

FL Carrot STD

ID Potato STD

3.9-6.0

1.7-1.8

0.4

0.1

0.3

0.1
11

Table 6. EDWCs for Pyraclostrobin Applications to Various Crops and Home Owner 

Garden

Drinking 

Water Source Crop

Crop Scenario

1-in-10-year 

Peak Exposure 

1-in-10-year 

Annual Mean 

Exposure 

30-year Mean 

Exposure 

Concentration (μg/L)

ME Potato STD 4.4-5.8 0.4-0.5 0.30.4

Small Fruit (Vine)

CA Grape STD

NY Grape STD

1.4-1.7

10.7-13.9

0.2

1.2-1.3

0.2

0.9

Sugarcane

FL Sugarcane STD

LA Sugarcane STD

6.7-9.9

9.6-13.8

0.8-0.7-08

0.9-1.0

0.05-0.08

0.7

Home Owner GardenWoody Ornamental

CA Residential STD 3.6 0.2 -

Groundwater Generic Scenario 6.08E-03 6.08E-03 6.08E-03

1 = Surface water EDWCs are estimated for aerial application

3

= The reported EDWCs are based on ground application to compare with the highest EDWCs for the PA Tomato 

scenario for aerial application. 

Table 7. PRZM-GW results based on pyraclotrobin use.

Crop Scenario

Highest

Daily

Value (μg/L)

Post 

Breakthrough

Average (μg/L)

Average Simulation 

Breakthrough Time 

(days)

Tomato

(0.20 lbs a.i./A x 6

applications)

FL citrus 6.15E-02 1.59E-02 Incomplete

FL potato 7.45E-11 1.68E-11 Incomplete

GA peanut 1.59E10 9.94E-12 Incomplete

NC cotton 4.88E-04 1.24E-04 Incomplete

DELMARVA sweet corn 5.54E-05 7.04E-06 Incomplete

WI corn 3.5E-09 2.23E-10 Incomplete

Monitoring Data

Data on pyraclostrobin were available in the United States Geological Survey (USGS) National 

Water-Quality Assessment (NAWQA) Program Data Warehouse 

(http://infotrek.er.usgs.gov/nawqa_queries/jsp/swmaster.jsp) searched on February 11, 2013. 

Pyraclostrobin was not detected in the surface water samples collected in Georgia (limit of 

quantitation (LOQ) = 2.8 ng/L). Ten bottom material samples were also collected in Georgia and 

pyraclostrobin was not detected (LOQ =1.6 μg/kg-sediment) in all ten samples. However, 

recently Reilly et al. (2012) reported pyraclostrobin residues in surface water and groundwater 

samples. For surface water, a total of 60 water samples were analyzed for pyraclostrobin.

Pyraclostrobin was detected in 42% of surface water samples. The maximum concentration of 

pyraclostrobin in surface water was 23.9 ng/L. For groundwater, a total of 12 water samples 
12

were analyzed for pyraclostrobin. Pyraclostrobin was detected in 40% of ground water samples.

The maximum concentrations of pyraclostrobin ranged from non-detect to 4.8 ng/L.

Drinking Water Treatment

There is no available information on the effects of drinking water treatment on pyraclostrobin. 

The EDWCs in this assessment are representative of concentrations in drinking water source 

water (pre-treatment). For surface water, the conceptual model assumes that a pesticide reaches 

surface water via spray drift or surface runoff and it is instantaneously mixed and concentrations 

are observed in the water body. Pyraclostrobin is stable to hydrolysis. Therefore, pyraclostrobin 

will not degrade by hydrolysis during the time that elapses from drinking water intake through 

distribution to the first tap. Pyraclostrobin is also stable to aqueous photolysis. Therefore, if 

ultraviolet light were used as a means of disinfection, degradation of pyraclostrobin would not be 

expected to be significant. Pyraclostrobin has long degradation rate in aerobic aquatic 

metabolism and aerobic metabolism is therefore, not expected to be a significant loss mechanism 

in water treatment. The most successful drinking water treatment process for removal of 

pesticides from drinking water is thought to be treatment with granular activated carbon (GAC) 

which is only used in larger drinking water treatment facilities. The ability of GAC to remove 

pesticides will vary with the properties of the chemical, the viability of the biofilm on the GAC, 

and whether the sorption sites on GAC have reached capacity (Badriyha et al., 2003; Zhao et al., 

1999). Data on the sorption of pyraclostrobin to GAC are not available; however, high Koc 

(9304 mL/g) value of pyraclostrobin suggests that there is a potential for removal of 

pyraclostrobin through GAC treatment due to its high adsorption coefficient. 

Uncertainties

The highest estimated concentrations provided in this assessment were generated from Tier 1 

models and are conservative estimates of pyraclostrobin concentrations in untreated drinking 

water. There were a number of uncertainties associated with this drinking water exposure 

assessment. The major uncertainty is from the use of the Tier I Rice Model with a modified 

depth for cranberries. This model only estimates a peak concentration inside the bog. Therefore, 

it likely overestimates chronic concentrations and is expected to be conservative for acute/peak 

EDWC as water will have a residence time between leaving a cranberry bog and reaching a 

drinking water intake. Additionally, the model was originally developed for rice and 

management of cranberries is different than rice and the model was not validated using 

monitoring data for cranberries. Therefore, there is some uncertainty in using the model for 

cranberries. Additionally, the Tier I Rice Model does not account for degradation and the annual 

average EDWC is likely overestimated; however, due to pyraclostrobin’s stability in water, the 

overestimation may not be that high.

An additional element of uncertainty derives from the conceptual model used in this assessment, 

whereby applications of pesticide are made to a single bog. In reality, the water used to flood a 

cranberry bog may be “recycled” and used to flood multiple bogs, and/or stored and used to reflood the same bog later during the year. Thus, the same volume of water may receive greater 

pesticide loadings than label restrictions would seem to imply. Additionally, applications may

be made to dry cranberry bogs that are subsequently flooded. 
13

Literature Cited

Jones, R. D., S. Abel, W. R. Effland, R. Matzner, R. Parker. 1998. An Index Reservoir for Use 

in Assessing Drinking Water Exposure. Proposed Methods for Basin-scale Estimation of 

Pesticide Concentrations in Flowing Water and Reservoirs for Tolerance Reassessment. 

Presentation to FIFRA Science Advisory Panel, June 29-30, 1998. Online at: 

http://www.epa.gov/scipoly/sap/1998/index.htm

Reilly, T.J., Smalling, K.L., Orlando, J.L. and K.M. Kuivila. 2012. Occurrence of boscalid and 

other selected fungicides in surface water and groundwater in three targeted use areas in 

the United States. Chemosphere 89:228-234.

USEPA, 2007. Pyraclostrobin. Outcome the the HED Metabolism Assessment Review 

Committee (MARC) Meeting Held on September 20, 2001. Health Effects Division. 

Office of Pesticide Programs. United States Environmental Protection Agency (D 

278044). 

USEPA, 2007. Drinking water assessment for turf and golf courses. Environmental Fate and 

Effects Division. Office of Pesticide Programs. United States Environmental Protection 

Agency (D D389729+. 

USEPA. 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides, Version 2.1. Environmental Fate and Effects Division. 

Office of Pesticide Programs. United States Environmental Protection Agency. Available 

at http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (Accessed 

February 10, 2013).

USEPA. 2010. Guidance on Development and Use of Percent Cropped Area Adjustment Factors 

in Drinking Water Exposure Assessments. Environmental Fate and Effects Division, 

Office of Pesticide Programs, United States Environmental Protection Agency. Available 

at http://www.epa.gov/oppefed1/models/water/pca_adjustment_dwa.pdf (Accessed 

November 29, 2010).

Zhao, X., Hickey, R. F., & Voice, T. C. 1999. Long-term evaluation of adsorption capacity in a 

biological activated carbon fluidized bed reactor system. Water Research, 33(13).
14

Appendix A: Model Outputs

Model: PRZM/EXAMS

stored as PATomG_DW_15-07.out

Chemical: Pyraclostrobin

PRZM environment: PAtomatoSTD.txt, modified Tueday, 29 May 2007 at 14:01:58

EXAMS environment: ir298.exv, modified Tueday, 26 August 2008 at 06:14:08

Metfile: w14751.dvf, modified Tueday, 26 August 2008 at 06:15:00

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 5.9 5.1 2.7 1.5 1.1 0.4

1962 6.5 5.3 2.7 1.9 1.7 0.8

1963 6.7 5.5 2.9 2.3 1.7 0.7

1964 3.3 2.8 1.9 1.4 1.2 0.7

1965 3.6 3.1 1.9 1.1 0.9 0.5

1966 17.5 14.1 7.1 3.3 2.6 1.0

1967 4.0 3.3 2.3 1.5 1.2 0.7

1968 16.1 12.8 6.2 2.9 2.3 0.8

1969 8.9 7.1 4.5 2.1 1.6 0.6

1970 4.5 3.6 2.0 1.4 1.0 0.7

1971 5.4 4.5 2.5 1.8 1.3 0.7

1972 7.1 5.9 4.5 2.7 1.8 1.0

1973 16.6 13.3 6.6 3.2 2.4 1.0

1974 9.5 7.8 4.7 2.4 1.9 0.9

1975 24.5 19.7 10.6 5.1 3.7 1.2

1976 10.5 8.6 4.9 3.0 2.4 1.0

1977 2.4 2.1 1.6 1.3 1.2 0.6

1978 1.8 1.5 1.1 0.9 0.9 0.5

1979 7.6 6.2 4.1 2.5 1.8 1.0

1980 8.1 6.6 3.4 2.6 1.9 0.6

1981 4.6 3.7 2.0 1.2 1.0 0.6

1982 3.3 2.7 1.5 0.9 0.7 0.5

1983 5.8 5.0 3.3 2.2 1.9 0.8

1984 3.4 2.8 1.5 1.1 1.0 0.6

1985 5.6 4.5 2.3 1.5 1.4 0.6

1986 5.1 4.1 2.3 1.3 1.0 0.7

1987 8.5 7.0 5.6 2.8 2.4 0.9

1988 3.7 3.0 1.6 1.0 0.7 0.5

1989 8.3 6.7 3.7 1.9 1.8 0.8

1990 6.1 5.0 2.8 1.8 1.7 0.8

Sorted results

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

0.0 24.5 19.7 10.6 5.1 3.7 1.2
15

0.1 17.5 14.1 7.1 3.3 2.6 1.0

0.1 16.6 13.3 6.6 3.2 2.4 1.0

0.1 16.1 12.8 6.2 3.0 2.4 1.0

0.2 10.5 8.6 5.6 2.9 2.4 1.0

0.2 9.5 7.8 4.9 2.8 2.3 1.0

0.2 8.9 7.1 4.7 2.7 1.9 0.9

0.3 8.5 7.0 4.5 2.6 1.9 0.9

0.3 8.3 6.7 4.5 2.5 1.9 0.8

0.3 8.1 6.6 4.1 2.4 1.8 0.8

0.4 7.6 6.2 3.7 2.3 1.8 0.8

0.4 7.1 5.9 3.4 2.2 1.8 0.8

0.4 6.7 5.5 3.3 2.1 1.7 0.8

0.5 6.5 5.3 2.9 1.9 1.7 0.7

0.5 6.1 5.1 2.8 1.9 1.7 0.7

0.5 5.9 5.0 2.7 1.8 1.6 0.7

0.5 5.8 5.0 2.7 1.8 1.4 0.7

0.6 5.6 4.5 2.5 1.5 1.3 0.7

0.6 5.4 4.5 2.3 1.5 1.2 0.7

0.6 5.1 4.1 2.3 1.5 1.2 0.6

0.7 4.6 3.7 2.3 1.4 1.2 0.6

0.7 4.5 3.6 2.0 1.4 1.1 0.6

0.7 4.0 3.3 2.0 1.3 1.0 0.6

0.8 3.7 3.1 1.9 1.3 1.0 0.6

0.8 3.6 3.0 1.9 1.2 1.0 0.6

0.8 3.4 2.8 1.6 1.1 1.0 0.5

0.9 3.3 2.8 1.6 1.1 0.9 0.5

0.9 3.3 2.7 1.5 1.0 0.9 0.5

0.9 2.4 2.1 1.5 0.9 0.7 0.5

1.0 1.8 1.5 1.1 0.9 0.7 0.4

0.1 16.6 13.3 6.6 3.2 2.4 1.0

Average 

of yearly 

averages

:

0.7

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: PATomG_DW_15-07

Metfile: w14751.dvf

PRZM 

scenario:

PAtomatoSTD.txt

EXAMS ir298.ex
16

environ

ment 

file:

v

Chemica

l Name:

Pyraclostrobin

Descripti

on

Variable 

Name

Value Units Comments

Molecul

ar 

weight

mwt 388 g/mol

Henry's 

Law 

Const.

henry 1.30E-07 atm-m^3/mol

Vapor 

Pressure

vapr 6.88E-07 torr

Solubilit

y

sol 2.7 mg/L

Kd Kd mg/L

Koc Koc 9304 mg/L

Photolys

is halflife

kdp 0.11 days Half-life

Aerobic 

Aquatic 

Metaboli

sm

kbacw 45.1 days Halfife

Anaerob

ic 

Aquatic 

Metaboli

sm

kbacs 12.1 days Halfife

Aerobic 

Soil 

Metaboli

sm

asm 247.2 days Halfife

Hydrolys

is:

pH 7 0 days Half-life

Method: CAM 2 integer See PRZM manual

Incorpor

ation 

Depth:

DEPI 0 cm

Applicati

on Rate:

TAPP 0.22 kg/ha

Applicati

on 

Efficienc

y:

APPEFF 0.99 fraction
17

Spray 

Drift

DRFT 0.064 fraction of application rate applied to pond

Applicati

on Date

Date 15-07 dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 

1

interval 7 days Set to 0 or delete line for single app.

app. rate 

1

apprate 0.2 kg/ha

Interval 

2

interval 14 days Set to 0 or delete line for single app.

app. rate 

2

apprate 0.2 kg/ha

Interval 

3

interval 7 days Set to 0 or delete line for single app.

app. rate 

3

apprate 0.2 kg/ha

Interval 

4

interval 14 days Set to 0 or delete line for single app.

app. rate 

4

apprate 0.2 kg/ha

Interval 

5

interval 7 days Set to 0 or delete line for single app.

app. rate 

5

apprate 0.2 kg/ha

Record 

17:

FILTRA

IPSCND 1

UPTKF

Record 

18:

PLVKRT

PLDKRT

FEXTRC 0.5

Flag for 

Index 

Res. Run

IR Reservoi

r

Flag for 

runoff 

calc.

RUNOFF total none, monthly or total(average of entire run)
18

Model SCIGROW

SCIGROW

VERSION 2.3

ENVIRONMENTAL FATE AND EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS

U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL

FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

chemical:Pyraclostrobin

time is 2/10/2013 7:50:44

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

Application Number of Total Use Koc Soil Aerobic

rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

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

0.156 6.0 0.936 9.00E+03 161.0

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

groundwater screening cond (ppb) = 6.18E-03

************************************************************************

Model PRZM_GW