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OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

 

 

 

 PC Code: 121027

 DP Barcode: D407566

 

MEMORANDUM April 23, 2013

SUBJECT: Drinking Water Assessment for the IR-4 New Use Petitions for the Use of 

Methoxyfenozide on Herb Subgroup 19A (except chives), Dates, 

Sorghum, Fruiting Vegetable Group 8-10, Pome Fruit Group 11-10, Berry

Subgroups 13-07 A, F & G and Tropical Tree Fruits.

TO: Elizabeth Holman, Dietary and Risk Assessor

 William Drew, Chemist

 Risk Assessment Branch II

 Health Effects Division, 7509P

CC: Laura Nollen, Risk Manager

 Risk Integration Minor Use & Emergency Response Branch

 Mark Suarez, Product Manager Insecticide Branch

 Registration Division, 7505P

FROM: Karen Milians, Ph.D., Chemist

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P)

REVIEWED

BY: Jim Carleton, Ph.D., Senior Scientist

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P)

APPROVED

BY: Marietta Echeverria, Branch Chief

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P)
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1. EXECUTIVE SUMMARY

EFED has reviewed the IR-4 request for methoxyfenozide (Intrepid®2F) 

registration on herb subgroup 19A (except chives), dates, sorghum, fruiting vegetable 

group 8-10, pome fruit group 11-10, berry subgroups 13-07 A, F & G, and tropical tree 

fruits (sugar apple, cherimoya, atemoya, custard apple, ilama, soursop, and biriba). The 

maximum proposed single application rates for these crops range from 0.06 to 0.31 lbs 

a.i./acre, and the maximum seasonal rates range from 0.75 to 1.0 lbs a.i./acre. 

The last drinking water assessment was completed in August 2011 for new uses 

on root vegetables subgroup 1B and citrus (USEPA, 2011). The estimated drinking water 

concentrations (EDWCs) were based on the globe artichoke use represented by the CA 

lettuce scenario.

Table 1 lists the EDWCs recommended for use in HED’s dietary risk assessment. 

These values are based on the globe artichoke use represented by the CA lettuce scenario 

with an application rate of 0.25 lbs. a.i./acre/application and a total of 1.0 lb 

a.i./acre/season. The surface water EDWCs are slightly higher than EDWCs reported in 

previous assessments (68.8, 43.4 and 31.8 ppb for acute, chronic, and cancer, 

respectively). The EDWCs are higher because of changes in the input parameters (to 

reflect current EFED policies) and a new PCA number used for all crops (USEPA, 

2012a). Similarly, the groundwater EDWCs listed in Table 1 are higher than those 

reported in the most recent assessments (USEPA 2011) mainly because of the 

implementation of a new groundwater model; PRZM-GW, which accounts for pesticide 

fate in the crop root zone and multiple years of application. 

EFED continues to have concerns that the combination of high persistence and 

moderate mobility of methoxyfenozide makes it plausible that this compound may pose a 

greater long-term risk than what is suggested by the screening-level drinking water 

assessments. In particular, once introduced into the environment, this compound could 

migrate to sensitive environmental compartments and persist for extended periods of 

time. One outstanding data requirement from the conditional registration of this 

compound is for the monitoring of surface water and sediment in a representative sample 

of high use areas in proximity to surface water. The main purpose of this study is to 

address EPA’s concern that multiple years of IntrepidTM use may result in accumulation 

of methoxyfenozide residues in water and/or sediment. DAS (Dow Agricultural Science) 

has recently submitted an interim report regarding the monitoring study in lotic (flowing) 

(e.g. rivers) and lentic water bodies (e.g. ponds) as well as sediment in each of the 

following states: California, Mississippi, and Michigan. More details of the report are 

provided in the following sections. The final monitoring report is expected to be 

submitted by DAS by March 18, 2014 (USEPA 2011).

 

Table 1. Tier II estimated drinking water concentrations (EDWCs) resulting from 

applications of methoxyfenozide (PRZM-EXAMS)

Drinking water 

source 

Use

(modeled rate)

1-in-10 year 

acute (ppb)

1-in-10 year 

chronic (ppb)

30- year average 

(ppb)

Surface water

(aerial application)

Globe Artichoke

(0.25 lb a.i./A x 4 

applic.; total of 1.0 

lb/A/yr)

77.7 51.6 37.4
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Table 1. Tier II estimated drinking water concentrations (EDWCs) resulting from 

applications of methoxyfenozide (PRZM-EXAMS)

Drinking water 

source 

Use

(modeled rate)

1-in-10 year 

acute (ppb)

1-in-10 year 

chronic (ppb)

30- year average 

(ppb)

Surface water

(ground application)

Globe Artichoke

(0.25 lb a.i./A x 4 

applic.; total of 1.0 

lb/A/yr)

77.4 50.4 35.8

Tier I EDWCs for Groundwater (PRZM-GW)

Crop/Scenario Highest Daily 

value (μg/L)

Post 

Breakthrough 

Average (μg/L)

Average Simulation 

Breakthrough Time 

(days)

Fruiting Vegetable/WI corn 251 214 8684.63

Value in bold show the highest EDWC, which is recommended for use in HED’s dietary risk assessment.

2. USE CHARACTERIZATION

Methoxyfenozide is currently registered for use on dried peas and beans (except 

soybean), pomegranate, popcorn, citrus, corn, cotton, cucurbit vegetables, grapes, pome 

and stone fruits, root vegetables, spearmint and peppermint, berries (including 

strawberries and cranberries), tree nuts, leafy vegetables, globe artichokes, legume 

vegetables, a variety of tropical fruits, black-eyed and southern peas, bushberries, dry

beans, grass forage, peanuts, tuberous and corm vegetables, non-grass forage, avocado, 

green onion, ornamentals, and root vegetables. Methoxyfenozide is the sole active 

ingredient in Intrepid®2F and Intrepid 80WSP, and it is applied aerially or through 

ground equipment. 

The maximum single application rates for the proposed IR-4 new uses are listed 

in Table 2. 

Table 2. Summary use information for methoxyfenozide proposed new uses, based on 

Intrepid®2F supplemental label (EPA Reg. No. 62719-442).

Use Max. Single 

Application 

Rate 

(lbs. a.i./A)

Max. No. of 

Applications 

Max. 

Seasonal1

Application

Rate (lbs. 

a.i./A)

Min. 

Application 

Interval 

(days)

Application

Method

Comments

Herb 

subgroup 

19A

0.25 Not stated on 

label. 1.0 10 Ground spray (foliar)/Aerial

Dates 0.31 Not stated on 

label. 1.0 10 Ground spray (foliar)
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Sorghum 0.16 Not stated on 

label. 0.75 10 Ground spray (foliar)/Aerial

Min 

application 

interval was 

only 

specified for 

beet 

armyworm 

and fall 

armyworm

Fruiting 

vegetable 

group 8-10

0.25 Not stated on 

label. 1.0 7

Ground spray 

(foliar)/Aerial

Pome fruit 

group 11-10 0.25 Not stated on label. 1.0 10 Ground spray (foliar)/Aerial

Aerial 

application is 

allowed only

for the last 

two 

applications

prior to 

harvest

Caneberries

subgroups 

13-07 A

0.25 3 0.75 7

Ground spray 

(foliar)/Aerial

Berry 

subgroups 

13-07 G

0.19 Not stated on 

label. 1.0 10 Ground spray (foliar)/Aerial

Small fruit 

vine

subgroups 

13-07 F

0.25 Not stated on 

label. 0.75 10 Ground spray (foliar)/Aerial

Tropical tree 

fruits 0.25 5 1.0 6

Ground spray 

(foliar)/Aerial

1

For the purposes of this assessment, the maximum annual use rate was assumed to be equal to the reported 

“per season” rate (i.e., it was assumed only one crop per year would be grown). Use on more than one crop 

per year (either the same crop or other crops with registered methoxyfenozide uses) on the same site may 

require further assessment to determine new estimated drinking water concentrations.

3. ENVIRONMENTAL FATE AND TRANSPORT CHARACTERIZATION

Methoxyfenozide is very persistent (t1/2 = 1 to 3 years in soil and water) and 

moderately mobile (Koc = 219 – 922 L/kgoc in various soils). It is stable to photolysis and 

hydrolysis, is not significantly volatile, and degrades only very slowly by microbial 

activity. Degradates are predominantly RH-117236 (3,5-Dimethylbenzoic acid N-tertbutyl-N’-(3-hydroxy-2-1nethylbenzoyl)hydrazide) and RH-131154 (3-[N-tert-butyl-N’-

(3-methoxy-2-methylbenzoyl)-hydrazinocarbonyl]-5-methylbenzoaicci d), but these were 

only found at low concentrations (less than 10% of the applied radioactivity) in 

submitted studies. Because of its resistance to degradation and its mobility, 
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methoxyfenozide has the potential to accumulate and to move off the site of application 

by leaching and erosion/runoff. Table 3 summarizes the physico-chemical properties of 

methoxyfenozide. For further details on the environmental fate and transport of 

methoxyfenozide, please refer to DP Barcode D249466.

Table 3. General Chemical Properties and Environmental Fate Parameters of 

Methoxyfenozide.

Chemical/Fate Parameter Value Source

Chemical name n-tert-butyl-N’-[2-methyl-3-

methoxybenzoyl]-3,5-

dimethylbenzohydrazide

D249466

Molecular mass 368 g/mol D249466

Vapor pressure (25C) 2.0 x 10-8

torr D249466

Solubility (25C) 3.3 mg/L D249466

Octanol-water partition coefficient (Kow) 103.72 D249466

Organic carbon partitioning coefficient (Koc, L/kgoc) 267, 922, 678, 219, 365 MRID 44144433

Soil partition coefficient (Kd, L/kg) 4.2, 1.1, 1.2, 6.2, 3.8 MRID 44144433

Hydrolysis half-life (pH 5, 7, 9) Stable MRID 44144430

Aqueous photolysis half-life Stable MRID 44617805

Soil photolysis half-life Stable MRID 44617806

Aerobic soil metabolism half-life 573, 1100, 772, 336 d MRIDs 44617808, 44617807, 

4414432

Aerobic aqueous metabolism half-life 387, 962 d MRID 44617809

Anaerobic aqueous metabolism half-life 654 d MRID 44617810

Terrestrial field dissipation half-life 237, 139, 151, 92 d MRID 44617812, 44617811

4. DRINKING WATER MODELING

EDWCs were generated using EFED’s standard suite of models. The proposed 

new IR-4 uses on herb subgroup 19A (except chives), date, sorghum, pea and bean 

subgroup 6C (except blackeyed and southern pea), fruiting vegetable group 8-10, pome 

fruit group 11-10, berry subgroups 13-07 A, F & G, and tropical tree fruits (sugar apple, 

cherimoya, atemoya, custard apple, ilama, soursop, and biriba) were assessed.

Additionally, the globe artichoke use that was assessed in the last DWA (USEPA 2011)

was included in this assessment for characterization purposes.

Models

The Pesticide Root Zone Model (PRZM 3.12.2 dated May 12, 2005) and 

Exposure Analysis Modeling System (EXAMS 2.98.04.06 dated April 25, 2005) are 

simulation models coupled with the input shell PE 5.0 (US EPA, 2006) to generate 

EDWCs of methoxyfenozide residues that may occur in surface water used as drinking 

water. The PRZM model simulates transformation on and movement from an 

agricultural field of a pesticide following its application. The EXAMS model simulates 
Page 6 of 20

resulting pesticide concentrations in an adjacent waterbody. For surface water/drinking 

water, EFED assumes the field to constitute a standard watershed 172.8 ha in area

draining into an adjacent drinking water reservoir 5.26 ha in area, with a mean depth of 

2.74 m. A more detailed description of this “Index Reservoir” and its watershed can be 

found in Jones et al., 1998. The PRZM and EXAMS models and their user’s manuals 

may be downloaded from the U.S. Environmental Protection Agency (EPA) Water 

Models web-page (US EPA, 2006). Percent Cropped Area (PCA) adjustment factors that

account for the maximum percent area within a watershed that may be planted with the 

modeled crop are used to adjust concentrations estimated by PRZM and EXAMS 

(USEPA, 2012).

Tier 1 groundwater EDWCs for methoxyfenozide, resulting from the chemical’s 

use on fruiting vegetable, were derived with PRZM-GW (Pesticide Root Zone Model for 

Groundwater, version 1.0, August 31, 2012), using the PRZM-GW GUI (Graphical User 

Interface, version 1.0, August 31, 2012). PRZM-GW is a one-dimensional leaching

model that estimates potential 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 

was used to simulate 30 years of repeated methoxyfenozide application in six standard 

scenarios: Delmarva, GA coastal, NC cotton, WI corn, FL potato and FL citrus. Each 

scenario represents a different location known to be vulnerable to groundwater 

contamination. The input parameters are found in Table 6. PRZM-GW outputs 

represent pesticide concentrations in a vulnerable groundwater supply located directly 

beneath an agricultural field (Table 9). The results show the greatest single-day 

maximum concentration for the WI corn scenario. 

Additionally, tier 1 groundwater EDWCs for methoxyfenozide were developed 

using the Screening Concentration In GROund Water (SCI-GROW v2.3, Jul. 29, 2003) 

model. SCI-GROW is a regression model used as a screening tool to estimate pesticide 

concentrations found in ground water used as drinking water. SCI-GROW was 

developed by fitting a linear model to ground water concentrations with the Relative 

Index of Leaching Potential (RILP) as the independent variable. Ground water 

concentrations were taken from 90-day average high concentrations from Prospective 

Ground Water monitoring studies. The RILP is a function of a pesticide’s aerobic soil 

metabolism and soil-water partition coefficient. The output of SCI-GROW represents 

concentrations of methoxyfenozide that might occur in shallow, unconfined aquifers 

under sandy soils. Such locations are representative of groundwater that is likely to be 

maximally vulnerable to pesticide contamination, and that may serve as a drinking water 

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

EPA Water Models web-page (US EPA, 2006). 

Input Parameters

Input parameters for the PRZM/EXAMS, PRZM-GW and SCI-GROW models

are listed in Tables 4 -5, 6 and 7, respectively. Explanations of various model input 

parameters are discussed below.
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Table 4. PRZM and EXAMS application-specific input parameters for methoxyfenozide 

Uses PRZM 

Scenario

Max App 

rate (lbs 

ai/A)1

# 

Apps

Interval

(days)

% Drift/ Efficiency CAM/IPSCND2 Date of 1st

of 

application

Herb Subgroup 

19 A

OR mint 0.25 4 10 0.16/0.95 2/3 April 15th

OR mint 0.25 4 10 0.064/0.99 2/3 April 15th

Dates

3 CA citrus with 

irrigation

0.31 3 10 0.064/0.99 2/3 Aug 1st

Sorghum4 KS sorghum 0.16 4 10 0.16/0.95 2/3 June 1st

KS sorghum 0.16 4 10 0.064/0.99 2/3 June 1st

Fruiting 

vegetable group 

8-10

PA tomato 0.25 4 7 0.16/0.95 2/3 June 30th

PA tomato 0.25 4 7 0.064/0.99 2/3 June 30th

FL tomato 0.25 4 7 0.16/0.95 2/3 Sep 10th

FL tomato 0.25 4 7 0.064/0.99 2/3 Sep 10th

FL pepper 0.25 4 7 0.16/0.95 2/3 Nov 1st

FL pepper 0.25 4 7 0.064/0.99 2/3 Nov 1st

Pome fruit5

group 11-10

PA apple 0.25 4 10 0.16/0.95 2/3 May 16th

PA apple 0.25 4 10 0.064/0.99 2/3 May 16th

Caneberries 

subgroups6

13-07 A

OR berries 0.25 3 7 0.16/0.95 2/3 May 1st

OR berries 0.25 3 7 0.064/0.99 2/3 May 1st

Berry 

subgroups 

10-07 G

FL strawberries 0.19 5 10 0.16/0.95 2/3 Nov 10th

 

FL strawberries 0.19 5 10 0.064/0.99 2/3 Nov 10th

 

Small fruit vine 

groups6

13-07 F

OR berries 0.25 3 10 0.16/0.95 2/3 May 1st

OR berries 0.25 3 10 0.064/0.99 2/3 May 1st

Tropical tree 

fruits

FL avocado 0.25 4 6 0.16/0.95 2/3 Mar 1st

FL avocado 0.25 4 6 0.064/0.99 2/3 Mar 1st

1. Maximum application rates were multiplied by 1.12 to convert to kg a.i./ha for use in modeling.

2. Chemical application method (CAM) and post-harvest foliar pesticide disposition (ISPCND). CAM 2 = foliar 

application; ISPCND 3= the pesticide is left as-is on foliage.

3. Three applications were modeled using 0.31 lb a.i./A, and a fourth application using 0.07 lb a.i./A

4. Four applications were modeled using 0.16 lb a.i./A, and a fifth application using 0.11 lb a.i./A

5. Previous assessments used 6 applications/yr and a higher application rate. Current label reflects a slightly 

lower single application rate of 0.25 lb a.i./A and a maximum of 1.0 lb a.i./acre/season.

6. There is not a standard scenario available for either the caneberry or small fruit vine groups. The OR berries 

OP scenario was used because this scenario provides the best representation of agricultural practices for these 

crops from among the available EFED-approved PRZM scenarios. 

Table 5. PRZM/EXAMS chemical-specific input parameters for methoxyfenozide. 

Input Parameter Value Comment Source

Molecular Mass (g/mol) 368 Product chemistry data D249466
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Table 5. PRZM/EXAMS chemical-specific input parameters for methoxyfenozide. 

Input Parameter Value Comment Source

Vapor Pressure at 25°C (torr) 2.0 x 10-8Product chemistry data D249466

Solubility in Water at 25oC 

(mg/L)

3.3 D249466

Organic Carbon Partition 

Coefficient (KOC) (L/kgOC)

490 Represents the average KOC. MRID 44144433

Aerobic Soil Metabolism Halflife (days)960 Represents the 90th %-ile confidence bound on 

the mean half-life.

MRIDs 44617808, 

44617807, 4414432

Aerobic Aquatic Metabolism 

Half-life (days)

1559 Represents the 90th %-ile confidence bound on 

the mean half-life.

MRID 44617809

Anaerobic Aquatic Metabolism 

Half-life (days)

1962 3x one data point MRID 44617810 

Hydrolysis Half-lives (days) 0 Stable MRID 44144430

Aqueous Photolysis

Half-life (days)

0 Stable MRID 44617805

Foliar Degradation Half-life 

(days)

0 Stable, no data Default

Foliar Washoff Extraction 

Coefficient (cm-1)

0.5 Default

Table 6. PRZM-GW Input Parameters

Parameter (units) Input Value Data Source

Application Rate 0.25 lbs a.i./A Label

Number of Applications 4 Label

Application Dates

(month/day)

06/30; 07/07; 07/14; 07/21 IPM center

Annual Application Retreatment Once every year

Hydrolysis Half-life (days) Stable (0) MRID 44144430

Soil Metabolism Half-life (days)

960 (90th percentile

confidence bound on the 

mean)

MRIDs 44617808, 44617807, 

4414432

average of Koc (mL/goc) 490 MRID 44144433

Table 7. SCI-GROW input parameters for methoxyfenozide. 

Input Parameter Value Comment Source

Application Rate (lbs 

a.i./A)

See Table 4 Label directions Proposed and 

current labels

Applications per Year See Table 4 Label directions Proposed and 

current labels

Organic Carbon Partition 

Coefficient (kOC) (L/kgOC)

219 Lowest KOC value; > 3x 

variation in data

MRID 44144433
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Table 7. SCI-GROW input parameters for methoxyfenozide. 

Input Parameter Value Comment Source

Aerobic Soil Metabolism

Half-life (days)

695 Average of 4 values MRIDs 44617808, 

44617807, 

4414432

Ten currently approved PRZM scenarios were used in the modeling for new uses:

OR mint, CA citrus, KS sorghum, MI beans, PA tomato, FL pepper, PA apple, OR 

berries, FL strawberries and FL avocado. The chemical application method (CAM)

parameter was derived from information on the supplemental label (Intrepid 2F), as were

the application rate and retreatment interval. The retreatment interval represents the 

minimum amount of time required between applications of the pesticide. Most crops 

were modeled using aerial and ground application except dates, for which only ground 

application was modeled.

Table 4 lists the specific PRZM/EXAMS scenarios modeled to represent the new 

uses. The highest simulated single application rate was 0.31 lb a.i./acre on dates, which 

was represented using the CA citrus scenario because no approved date scenario exists, 

and 100% of dates in the U.S. are cultivated in California. Similarly, there are no 

approved standard scenarios for caneberries or small fruit vine group 10-07 F, therefore 

the Oregon berry OP (organophosphate) scenario was used because this scenario provides 

the best representation of agricultural practices for these crops from among the available 

approved PRZM scenarios. The application dates for the scenarios were chosen 

according to the crops’ profiles, lifecycle, and/or time when heavy pest pressure is likely 

to appear (USDA Crop Profiles). 

Chemical property model input values were chosen in accordance with EFED’s 

current input parameter guidance (USEPA 2009 and USEPA 2012b). The upper 90% 

confidence limit on the mean half-life (960 d) was selected to represent aerobic soil 

metabolism in surface water modeling and PRZM-GW, and the median half-life (695 d) 

was used in SCI-GROW modeling, in accordance with the input parameter guidance.

Both hydrolysis and photolysis were modeled as stable. The upper 90% confidence limit

on the mean half-life (1559 d) was selected to represent aerobic aquatic metabolism, and 

3 times the anaerobic aquatic metabolism half-life was used to represent anaerobic 

aquatic metabolism since only one measured value (1962 d) was available. The default 

all-agriculture PCA of 0.91 was used for all simulations (USEPA 2012a). The mean Koc

(490 L/kgoc) was used for PRZM-GW and PRZM/EXAMS modeling, whereas the lowest 

Koc value (219 L/kgoc) was used in the SCI-GROW modeling.

Modeling Results

The EDWCs for application of methoxyfenozide on the new uses and the 

previously evaluated globe artichoke use are listed in Table 8. The EDWCs obtained for 

the globe artichoke use pattern as represented by the CA lettuce scenario, generated the 

highest EDWCs for both surface water and groundwater, followed by the fruiting 

vegetable group uses as represented by the FL tomato scenario. EDWCs for Tier I 

PRZM-GW are shown in Table 9. The highest EDWCs are associated with the WI corn 

scenario, and are recommended for use in HED’s dietary assessment. Refer to 
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Attachment 1 for more details on the PRZM/EXAMS, PRZM-GW and SCI-GROW 

modeling outputs.

Table 8. Maximum Concentrations of methoxyfenozide: Tier II EDWCs for surface water. 

Bolded values are the maximum values found for the crops1,2

Use Application 

Method

PRZM

Scenario

Maximum 

Applicatio

n Rate

[lb. a.i./A; 

kg/ha]

No.

of 

Apps

1-in-10 

Year

Acute

(μg/L)

1-in-10 

Year 

Chronic

(μg/L)

30- Year 

Average 

(μg/L)

Herb 

Subgroup 

19

aerial OR mint 0.25/0.28 4 12.6 7.2 6.2

ground OR mint 0.25/0.28 4 8.3 4.7 3.7

Dates ground

CA citrus with 

irrigation 0.31/0.35 3 16.5 14.6 11.7

Sorghum

aerial KS sorghum 0.16/0.18 5 28.5 13.1 9.9

ground KS sorghum 0.16/0.18 5 27.7 12.5 9.1

Fruiting 

vegetable 

group

8-10

aerial PA tomato 0.25/0.28 4 34.3 17.2 11.7

ground PA tomato 0.25/0.28 4 32.9 16.1 10.3

aerial FL tomato 0.25/0.28 4 75.6 13.3 9.0

ground FL tomato 0.25/0.28 4 75.9 13.3 8.8

aerial FL pepper 0.25/0.28 4 51.6 11.7 6.5

ground FL pepper 0.25/0.28 4 51.0 11.6 6.2

Pome fruit 

group 11-

10

aerial PA apple 0.25/0.28 4 39.5 20.1 14.1

ground PA apple 0.25/0.28 4 38.9 18.4 12.2

Caneberries

subgroups

13-07 A

aerial OR berries3

0.25/0.28 3 9.2 6.0 5.3

ground OR berries30.25/0.28 3 6.8 4.2 3.5

Berry 

subgroups

10-07 G

aerial FL strawberries 0.19/0.21 5 26.1 6.5 36.8

ground FL strawberries 0.19/0.21 5 24.9 6.0 4.1

Small fruit 

vine groups

13-07 F

aerial OR berries3

0.25/0.28 3 9.1 6.2 5.4

ground OR berries30.25/0.28 3 7.0 4.4 3.6

Tropical 

tree fruits

aerial FL avocado 0.25/0.28 4 22.3 17.8 12.3

ground FL avocado 0.25/0.28 4 15.8 13.2 7.7

Globe 

Artichoke

aerial CA lettuce 0.25/0.28 4 77.7 51.6 37.4

ground CA lettuce 0.25/0.28 4 77.4 50.4 35.8

1. The annual rate for these crops do not exceed 1.0 lb a.i./acre/season.

2. PCA values are 0.91 for all the crops.

Bolded values represent the highest EDWCs for methoxyfenozide.
Page 11 of 20

Table 9. PRZM-GW (30 years simulation) and SCI-GROW EDWCs (1 year) in 

Groundwater Resulting from the Use of Methoxyfenozide.

Crop/Scenario

Highest 

Daily value 

(μg/L)

Post 

Breakthrough 

Average (μg/L)

Average 

Simulation 

Breakthrough 

Time (days)

Fruiting Vegetable/FL potato 30.4 30.3 10568.95

Fruiting Vegetable/ FL citrus 154 139 4243.13

Fruiting Vegetable/Delmarva 147 133 4264.59

Fruiting Vegetable/ NC cotton 180 157 5020.61

Fruiting Vegetable/GA coastal 62.7 52.9 8983.61

Fruiting Vegetable/WI corn 251 214 8684.63

SCI-GROW EDWCs 

Globe Artichoke (1.0 lb/A/yr) 4.13 μg/L

Bolded value represents the highest EDWC for methoxyfenozide

5. MONITORING DATA

Methoxyfenozide is not identified as a cause of impairment for any water bodies 

listed as impaired under section 303(d) of the Clean Water Act. 1The following databases 

and sources were searched on February 8, 2013 for monitoring information on 

methoxyfenozide:

 The United States Geological Survey (USGS) National Water-Quality 

Assessment (NAWQA) Program Data Warehouse 

(http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567)

2

 The USGS National Stream Quality Accounting Network (NASQAN) program 

(http://water.usgs.gov/nasqan/)3

No monitoring data for methoxyfenozide were found, as these programs did not include 

this compound in their lists of analytes. EFED is not aware of water or sediment 

monitoring data on methoxyfenozide from any other sources. Due to uncertainties 

identified during the Section 3 Registration process, methoxyfenozide is conditionally 

registered. One of the outstanding conditional registration requirements is:

Three years after use, obtaining approval for and conducting monitoring of 

surface water and sediment in a representative sample of high use areas in 

proximity to surface water.

DAS (Dow Agricultural Science) has agreed to sample for methoxyfenozide over 

a two-year period in lotic (flowing) water bodies (e.g. rivers) and lentic water bodies (e.g.

ponds) and sediment in each of the following states: California, Mississippi, and 

Michigan with the Agency’s guidance (USEPA 2011). A summary of interim sampling 

results is provided below in Table 10. For more information refer to USEPA, 2013. The 

 

1

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

2 http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567

3

http://water.usgs.gov/nasqan/)
Page 12 of 20

final monitoring report is expected to be submitted by DAS by March 18, 2014 (USEPA 

2011). 

Table 10. Summary of Interim Sampling Results

State Parameters

Lotic Lentic

Water (μg/L) Sediment 

(μg/kg)

Water 

(μg/L)

Sediment 

(μg/kg)

CA

Detects/Samples

Range

Mean/Median

72/72

0.018 – 1.0 

0.14/0.061

0/4 1/10

0.017

0/10

MI

Detects/Samples

Range

Mean/Median

0/14 0/2 8/11

0.025 – 0.85

0.19/0.06

1/11

3.4

MS

Detects/Samples

Range

Mean/Median

38/48

0.016 – 0.181

0.036/0.025

0/4 8/10

0.019 – 0.233

0.056/0.024

0/10

For water, the limit of detection (LOD) was 0.015 μg/L and the limit of quantitation (LOQ) was 

0.05 μg/L. For sediment, the LOD was 3 μg/kg and the LOQ was 10 μg/kg.

6. CONCLUSIONS

The EDWCs reported here are based on currently registered uses, and the 

following new uses: herb subgroup 19A (except chives) date, sorghum, fruiting vegetable 

group 8-10, pome fruit group 11-10, berry subgroups 13-07 A, F & G, and tropical tree 

fruits (sugar apple, cherimoya, atemoya, custard apple, ilama, soursop, and biriba). The 

fruiting vegetable group 8-10 use yielded the highest value for surface water EDWCs

from the new uses. However, the globe artichoke use generated the highest EDWCs from 

all currently registered uses of methoxyfenozide for surface water. Table 1 reflects the 

most conservative (highest) EDWCs, which are recommended for use in HED’s dietary

assessment. 

There remains an outstanding data requirement for monitoring of surface water 

and sediment in a representative sample of high use areas in close proximity to surface 

water. Additionally, EFED continues to have concerns that the persistence of 

methoxyfenozide makes it plausible that this compound may pose a greater long-term 

drinking water exposure concern than what is suggested by this screening-level 

assessment. Given its persistence and mobility, once introduced into the environment, 

this compound may enter sensitive environmental compartments such as aquatic 

sediment, and persist for extended periods of time. As such, EFED has concerns

regarding the potential for long-term drinking water exposure associated with the use of 

this chemical. 

There is also a continuing concern regarding label language. The proposed label 

currently specifies a maximum application rate on a seasonal basis rather than an annual 

basis. Given the persistence of methoxyfenozide, repeated applications on crops for 

which there is more than one growing season per year could result in greater 

accumulation and higher aquatic concentrations than reported in this assessment.
Page 13 of 20

References

USEPA. 2002. SCIGROW: Users Manual. Online at: 

http://www.epa.gov/oppefed1/models/water/#scigrow

USEPA. 2005. PRZM 3.12.2: Users Manual. Online at:

http://www.epa.gov/oppefed1/models/water/#przm

USEPA. 2005. EXAMS 2.98.04.06: Users Manual. Online at:

http://www.epa.gov/oppefed1/models/water/#exams

USEPA. 2006. Water models PE Version 5: User Manual. Online at:

http://www.epa.gov/oppefed1/models/water/pe5_user_manual.htm 

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

Fate and Transport of Pesticides. U.S. Environmental Protection Agency, 

Office of chemical Safety and Pollution Prevention, Office of Pesticide 

Programs, Environmental Fate and Effects Division, Oct. 22, 2009. Online at: 

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

USEPA. 2011. DP Barcode: D394308. Review of Addendum to Site Selection Report 

with Recommended Alternate Sampling Sites for Lentic Water Bodies in 

California (MRID 47809904) from Environmental Fate and Effects Division 

(EFED) to Pesticide Re-evaluation Division (PRD) from Chuck Peck to Clayton 

Myers. October 12, 2011.

USEPA. 2012a. Development and Use of Percent Cropped Area Adjustment Factors in 

Drinking Water Exposure Assessments. U.S. Environmental Protection Agency, 

Office of chemical Safety and Pollution Prevention, Office of Pesticide Programs, 

Environmental Fate and Effects Division, September 9, 2010. Online at: 

http://www.epa.gov/oppefed1/models/water/pca_adjustment_dwa.html

USEPA. 2012b. Guidance for Selecting Input Parameters for Modeling Pesticide 

Concentrations in Groundwater Using the Pesticide Root Zone Model. Office of 

chemical Safety and Pollution Prevention, Office of Pesticide Programs, 

Environmental Fate and Effects Division, and Health Canada Pesticide 

Management Regulatory Agency, Oct.15, 2012. 

USEPA. 2013. Methoxyfenozide: Review of Interim Report on Surface Water and 

Sediment Monitoring (MRID 49050001). Office of Chemical Safety and 

Pollution Prevention, Office of Pesticide Programs, From Environmental Fate and 

Effects Division (EFED) to Registration Division (RD); from Chuck Peck to 

Mark Suarez. March 26, 2013.

USEPA MEMORANDUM. DP Barcode: D249466. Methoxyfenozide: Tier II Drinking 

Water EECs for Use in the Human Health Risk Assessment from environmental 
Page 14 of 20

fate and effects division (EFED) to Registration Division (RD), from Dirk F. 

Young to Joseph Tavano and Arnold Layne, July 21, 1999.

US EPA MEMORANDUM. DP Barcode: 331949, 340542. Drinking Water Assessment 

for the Section 3 New Use Petitions for the Use of Methoxyfenozide on vegetable 

(tuberous and corm subgroup 1 D), bushberry (subgroup 13B), dry beans, grass, 

forage, fodder and hay (group 17), peanut, green onion (subgroup 3B), avocado, 

guava and related tropical fruits, from environmental fate and effects division 

(EFED) to Registration Division (RD), from Marietta Echeverria to John Redden, 

October 18, 2007.

US EPA MEMORANDUM. DP Barcode: D388876. Drinking Water Assessment for the 

IR-4 New Use Petitions for the Use of Methoxyfenozide on Root Vegetables for 

Crop Subgroup 1B (Except Sugar Beets) and Citrus Crop Group 10 from 

environmental fate and effects division (EFED) to Registration Division (RD), 

from Karen Milians to Richard Gebken August 17, 2011.

USDA Crop Profiles. Available online at: 

http://www.ipmcenters.org/cropprofiles/CP_form.cfm

Jones, R. David, Abel, Sidney, Effland, William, Matzner, Robert, and Parker, Ronald. 

1998. An Index Reservoir for Use in Assessing Drinking Water Exposure.

Chapter IV in Proposed Methods for Basin-Scale Estimation of Pesticide 

Concentrations in Flowing Water and Reservoirs for Tolerance Reassessment., 

presented to the FIFRA Science Advisory Panel, July 29, 1998.
Page 15 of 20

Attachment 1. Modeling Input and Output: 

Scenario/application rate: Globe Artichoke/0.25 lb ai/A

stored as caartnewae.out

Chemical: methox

PRZM environment: CAlettuceSTD.txt modified Tueday, 8 January 2013 at 16:16:28

EXAMS environment: ir298.exv modified Tueday, 26 August 2008 at 05:14:07

Metfile: w23273.dvf modified Wedday, 3 July 2002 at 08:04:22

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 46.36 45.71 43.36 27.23 19.11 6.558

1962 53.99 53.41 51.58 47.41 45.66 36.11

1963 57.25 56.63 54.66 52.15 51.3 40.88

1964 63.73 63.03 60.56 55.6 46.36 34.45

1965 74.16 73.68 70.72 55.82 46.57 40.31

1966 70.48 69.79 67.07 59.87 57.13 47.92

1967 71.34 70.71 68.53 64.07 62.4 50.46

1968 47.98 47.55 46.35 44.96 42.16 37.33

1969 49.61 49.33 48.32 45.61 43.73 36.54

1970 73.67 72.9 67.06 50.13 42.4 37.21

1971 69.62 68.95 66.3 61.3 58.22 48.13

1972 65.75 65.02 62.31 54.13 45.24 36.15

1973 57.86 57.35 55.38 53.54 51.58 43.3

1974 98.48 97.74 93.38 65.17 54.86 47.75

1975 94.59 93.63 89.9 87.9 85.12 64.88

1976 86.34 85.8 82.86 76.74 72.94 60.33

1977 77.07 76.65 74.39 69.61 66.53 57.03

1978 72.87 72.19 69.49 64.4 62.47 54.21

1979 58.86 58.5 57.57 55.75 54.1 44.28

1980 65.12 64.59 62.65 60.68 58.62 46.84

1981 65.9 65.5 63.26 61.26 59.22 47.7

1982 46.03 45.64 44.16 42.18 40.49 36.48

1983 45.57 45.25 44.31 42.45 41.29 36.91

1984 48.94 48.46 44.03 36.03 34.64 30.79

1985 52.59 52.07 50.11 41.56 39.52 34.55

1986 49.29 48.89 47.38 44.75 44.18 39.05

1987 51.42 50.99 47.71 45.15 42.53 38.99

1988 52.45 51.96 49.8 47.08 45.33 39.16

1989 50.58 50.14 48.42 45.29 43.27 34.47

1990 32.88 32.65 31.95 31.31 30.29 25.83

Sorted results

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

0.032258064516129 98.48 97.74 93.38 87.9 85.12 64.88

0.0645161290322581 94.59 93.63 89.9 76.74 72.94 60.33

0.0967741935483871 86.34 85.8 82.86 69.61 66.53 57.03

0.129032258064516 77.07 76.65 74.39 65.17 62.47 54.21

0.161290322580645 74.16 73.68 70.72 64.4 62.4 50.46

0.193548387096774 73.67 72.9 69.49 64.07 59.22 48.13

0.225806451612903 72.87 72.19 68.53 61.3 58.62 47.92

0.258064516129032 71.34 70.71 67.07 61.26 58.22 47.75

0.290322580645161 70.48 69.79 67.06 60.68 57.13 47.7

0.32258064516129 69.62 68.95 66.3 59.87 54.86 46.84

0.354838709677419 65.9 65.5 63.26 55.82 54.1 44.28

0.387096774193548 65.75 65.02 62.65 55.75 51.58 43.3

0.419354838709677 65.12 64.59 62.31 55.6 51.3 40.88

0.451612903225806 63.73 63.03 60.56 54.13 46.57 40.31

0.483870967741936 58.86 58.5 57.57 53.54 46.36 39.16

0.516129032258065 57.86 57.35 55.38 52.15 45.66 39.05

0.548387096774194 57.25 56.63 54.66 50.13 45.33 38.99

0.580645161290323 53.99 53.41 51.58 47.41 45.24 37.33
Page 16 of 20

0.612903225806452 52.59 52.07 50.11 47.08 44.18 37.21

0.645161290322581 52.45 51.96 49.8 45.61 43.73 36.91

0.67741935483871 51.42 50.99 48.42 45.29 43.27 36.54

0.709677419354839 50.58 50.14 48.32 45.15 42.53 36.48

0.741935483870968 49.61 49.33 47.71 44.96 42.4 36.15

0.774193548387097 49.29 48.89 47.38 44.75 42.16 36.11

0.806451612903226 48.94 48.46 46.35 42.45 41.29 34.55

0.838709677419355 47.98 47.55 44.31 42.18 40.49 34.47

0.870967741935484 46.36 45.71 44.16 41.56 39.52 34.45

0.903225806451613 46.03 45.64 44.03 36.03 34.64 30.79

0.935483870967742 45.57 45.25 43.36 31.31 30.29 25.83

0.967741935483871 32.88 32.65 31.95 27.23 19.11 6.558

0.1 85.413 84.885 82.013 69.166 66.124 56.748

Average of yearly averages: 41.1532666666667

Inputs generated by pe5.pl - Novemeber 2006

Data used for this run:

Output File: caartnewae

Metfile: w23273.dvf

PRZM scenario: CAlettuceSTD.txt

EXAMS environment file: ir298.exv

Chemical Name: methox

Description Variable Name Value Units Comments

Molecular weight mwt 368 g/mol

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

Vapor Pressure vapr 2e-8 torr

Solubilitysol 3.3 mg/L

Kd Kd mg/L

Koc Koc 490 mg/L

Photolysis half-life kdp 0 days Half-life

Aerobic Aquatic Metabolism kbacw 1559 days Halfife

Anaerobic Aquatic Metabolism kbacs 1962 days Halfife

Aerobic Soil Metabolism asm 960 days Halfife

Hydrolysis: pH 7 0 days Half-life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 0.28 kg/ha

Application Efficiency: APPEFF 0.95 fraction

Spray Drift DRFT 0.16 fraction of application rate applied to pond

Application Date Date 16-4 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 0.28 kg/ha

Interval 2 interval 7 days Set to 0 or delete line for single app.

app. rate 2 apprate 0.28 kg/ha

Interval 3 interval 7 days Set to 0 or delete line for single app.

app. rate 3 apprate 0.28 kg/ha

Record 17: FILTRA

IPSCND 3

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC0.5

Flag for Index Res. Run IR Reservoir

Flag for runoff calc. RUNOFFtotal none, monthly or total(average of entire run)

 SCIGROW

 VERSION 2.3

 ENVIRONMENTAL FATE AND EFFECTS DIVISION

 OFFICE OF PESTICIDE PROGRAMS
Page 17 of 20

 U.S. ENVIRONMENTAL PROTECTION AGENCY

 SCREENING MODEL

 FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3

chemical:Methoxyfenozide

time is 1/ 3/2013 16:23:59

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

 Application Number of Total Use Koc Soil Aerobic

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

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

 0.250 4.0 1.000 2.19E+02 695.0

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

groundwater screening cond (ppb) = 4.13E+00 

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

Note: The outputs for the scenarios mentioned here are attached on a separate file 

name: 121027_407566_DWAscenarios_041613.

121027_407566_DW

Ascenarios_041613

Fruiting Vegetable/FL potato (30 years simulation)

Fruiting Vegetable/FL citrus (30 years simulation)
Page 18 of 20

Fruiting Vegetable/Delmarva (30 years simulation)

Fruiting Vegetable/ NC cotton (30 years simulation)

Fruiting Vegetable/GA coastal (30 years simulation)
Page 19 of 20
Page 20 of 20

Fruiting Vegetable/WI corn (30 years simulation)