OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

January 23, 2012

PC Code: 129131

MEMORANDUM DP Barcode: 391431

SUBJECT: Fenpyroximate: Drinking Water Exposure Assessment for Proposed New Uses 

on Snap Beans and Tropical Fruits including Avocado and a Proposed Outdoor 

Use on Cucumbers

FROM: Greg Orrick, Environmental Scientist

ERB2/EFED (7507P)

THROUGH: James Lin, Environmental Engineer

Kristina Garber, Senior Biologist

Brian Anderson, Chief

ERB2/EFED (7507P)

TO: George Kramer, Ph.D., Senior Chemist

Dana Vogel, Chief

RAB1/HED (7509P)

Sidney Jackson, Product Manager

Barbara Madden, Team Leader, RM Team 5

RIMUERB/RD (7505P)

1. EXECUTIVE SUMMARY

This assessment provides estimated drinking water concentrations (EDWC) of 

fenpyroximate in surface water and in ground water in support of human health risk assessment. 

Screening EDWCs (Table 1) of fenpyroximate were generated with FIRST and a Provisional 

Cranberry Model for surface water and with SCI-GROW for ground water. Modeled use 

patterns are those of current and proposed end-use labels that result in the highest exposure. 

Model input parameters were chosen according to current guidance (USEPA, 2009). EDWCs 

reflect exposure in drinking water to the residues of concern of fenpyroximate, which include 

fenpyroximate parent, its cis isomer M-1, and its carboxylic acid M-3, all of which are assumed 

to have similar toxicity (USEPA, 2003). Labeled application buffers to fish-bearing waters were 

not modeled. The EDWCs listed in this assessment are the result of a coarse screen and do not 

necessarily reflect actual exposures that may occur or may have occurred. If the screening 

EDWCs listed in this assessment result in dietary risk exceedances, contact Greg Orrick (703-
2

305-6140) of Environmental Risk Branch II (7507P) to request a refined drinking water exposure 

assessment.

Table 1.1. Maximum Screening Drinking Water Exposure Estimates for Current and 

Proposed Fenpyroximate Uses A

Source (Tier: Model) Use (Maximum Annual 

Rate)

Peak Exposure 

(μg/L)

Annual Mean 

Exposure (μg/L)

Surface water (Tier I: FIRST) Ornamentals (0.69 lbs a.i./A) 29 1.9

Surface water (Tier I: Cranberry model) Cranberries (0.20 lbs a.i./A) 43 8.6

Ground water (Tier I: SCI-GROW) Ornamentals (0.69 lbs a.i./A) ≤0.27

A Maximum values in bold.

A maximum screening exposure estimate in fish that may be consumed by humans was 

also calculated with the Provisional Cranberry Model and KABAM, at 30 mg/kg-bw (ww).

Fenpyroximate is a pyrazole contact insecticide and miticide that inhibits mitochondrial

complex I electron transport. The compound is relatively nonvolatile, lipophilic, and may

bioconcentrate in fish. Fenpyroximate is slightly to hardly mobile in soil and may move to 

surface water through runoff of residues sorbed to suspended sediment. Fenpyroximate degrades 

mainly via moderate biodegradation in soil and water bodies (half-lives of 23-41 days in aerobic 

and anaerobic systems). The compound is also rapidly photoisomerized to reach equilibrium 

with its cis isomer M-1 and photolyzed in shallow, illuminated water (fenpyroximate half-life of 

1.5 hours; M-1 half-life of 10.5 hours). However, the importance of this degradation pathway is 

expected to be limited because fenpyroximate and its isomer are expected to partition to 

sediment in water bodies, where aqueous photolysis is limited.

Fenpyroximate’s cis isomer M-1, its carboxylic acid M-3, and cleavage products M-6, M8, M-11, M-16, and carbon dioxide are its major transformation products that were isolated in 

submitted environmental fate studies. M-1 and M-3 are included with the parent as residues of 

concern. Due to lack of toxicity data, the residues of concern are assumed to have equivalent 

toxicity (USEPA, 2003). Exposure estimates in this assessment reflect total residues of concern 

(TRC).

EPA Reg. No. 71711-4 states “Do not apply more than 48 fl oz per crop cycle or per 

growing season, whichever is longer.” This was interpreted as an annual application rate limit. 

However, the label language is vague and could be misinterpreted. It is recommended to reword 

this limitation as an annual application rate limit in terms of mass of active ingredient per area.

2. PROBLEM FORMULATION

This drinking water assessment uses environmental modeling to provide estimates of 

surface water and ground water concentrations in drinking water source water (pre-treatment) 

resulting from fenpyroximate use on vulnerable sites. Estimates reflect drinking water exposure 

to fenpyroximate residues of concern in drinking water, which include the parent compound, its

cis isomer M-1, and its carboxylic acid M-3 (chemical names and structures are in Table A.1,

Appendix A), on a per molar basis (USEPA, 2003). Primary routes of transport to source water 
3

include spray drift and runoff of dissolved residues (mainly M-3) and residues sorbed to 

suspended sediment (mainly fenpyroximate and M-1). Exposure in surface water from proposed 

and current fenpyroximate uses due to runoff, erosion, and spray drift was assessed with the Tier 

I screening model, FIRST, and a Provisional Cranberry Model. Exposure in ground water due to 

leaching was assessed with the Tier I screening ground water model SCI-GROW. Exposure in 

fish consumed by humans was assessed with the Provisional Cranberry Model and KABAM.

2.1. Nature of the Chemical

Fenpyroximate is a pyrazole contact insecticide and miticide that inhibits mitochondrial 

complex I electron transport. The mode of action blocks cell respiration by blocking formation 

of adenosine triphosphate (ATP), causing the target pest to lose motor control and collapse. 

Fenpyroximate specifically targets the proton-translocation in NADH:ubiquinone oxidoreductase 

enzyme blocking ubiquinone reduction.

NADH:ubiquinone oxidoreductase, also known as respiratory complex I of mitochondria, 

transfers electrons from NADH to ubiquinone (coenzyme Q) and links this process with 

translocation of protons across the inner membrane to the cytoplasmic side creating a proton 

gradient which drives the synthesis of ATP. NADH:ubiquinone oxidoreductase enzyme is 

comprised of a number of subunits. The number of subunits and total mass of this enzyme and 

density within mitochondria depends on the organism. It consists of at least 41 different subunits 

in mammals. The highest number of subunits is 46 for bovine heart mitochondria, whereas 

bacteria have a minimum of 14 subunits. The total mass of the enzymes ranges from 

approximately 500 to 1000 kiloDaltons (kDa), depending on the organism. Sensitivity of an 

organism to fenpyroximate is expected to be affected by the specific organism 

NADH:ubiquinone oxidoreductase enzyme affinity with fenpyroximate, the density of the 

NADH:ubiquinone oxidoreductase enzyme within mitochondria, and the presence of alternative 

energy pathways.

 

In addition to the acute respiratory activity, at sub lethal levels fenpyroximate causes 

inhibition of molting of all immature stages (as in insect growth regulators), inhibits oviposition, 

and decreases feeding action.

3. ANALYSIS

3.1. Use Characterization

Fenpyroximate is proposed for use on snap beans and tropical fruits including avocado. 

Use on greenhouse-grown cucumbers is also proposed to be expanded to include cucumbers 

grown outdoors. The proposed use of fenpyroximate on tropical fruits (including avocado) is by 

ground application at a maximum single application rate of 0.10 pounds of active ingredient per 

acre (lbs a.i./A). A second application may be made at this rate a minimum of 14 days later, to 

meet a seasonal application rate limit of 0.20 lbs a.i./A per growing season. Supplemental 

proposed labels propose the same application directions and limitations for snap beans and 

cucumbers (grown outdoors) as for tropical fruits.
4

The fenpyroximate uses of maximum aquatic exposure are the current uses on 

ornamentals and cranberries. The single and seasonal maximum application rates for 

ornamentals are 0.343 lbs a.i./A and 0.686 lbs a.i./A, respectively. The seasonal application rate 

limit was inferred based on a label statement to “not apply more than 48 fl oz per crop cycle or 

per growing season, whichever is longer.” It was assumed that this label statement was intended 

to be in terms of fl oz per acre per crop cycle or growing season, which results in the seasonal 

rate limit of 0.686 lbs a.i./A. A reapplication interval was not provided. Aerial application was 

not disallowed. Use directions for low-growing berries (including cranberries) are similar to 

those of the proposed uses. Table 3.1 lists all of the currently labeled and proposed maximum 

use patterns for fenpyroximate.
5

Table 3.1. Proposed and current uses of fenpyroximate

EPA 

Reg. No.

Active 

Ingredient (%) Use

Max. Single 

App. Rate

(lbs a.i./A)

Max. Annual 

App. Rate 

(lbs a.i./A)

App. 

Interval 

(d)

Application 

Type Additional Application Directions

71711-4

Fenpyroximate

(5%)

Ornamentals, Christmas trees, 

nonbearing fruit trees and vines 0.343 0.686 A Not stated Aerial or ground Do not use products with the same mode of 

Greenhouse cucumbers and action in consecutive applications.

tomotoes 0.105 0.42 14 Ground

71711-19 Fenpyroximate

(5%)

Avocado, black sapote, canistel, 

mamey sapote, mango, papaya, 

sapodilla, and star apple 0.10

0.20 B

14 Aerial or 

ground Do not apply within 75 feet of fish-bearing 

waters. Do not use products with the same 

mode of action in consecutive applications.

Snap beans

0.20 C Cucumbers

Melons (crop subgroup 9A) 0.10 Not stated

Low-growing berry (crop 

subgroup 13-07G) D 0.10 0.20 C

14

Ground

Citrus fruits (crop group 10) east 

of the Mississippi River 0.20 0.20 B

Aerial or 

ground

Do not apply by air except in FL and TX. 

Do not apply within 75 feet of fish-bearing 

waters. For aerial use in FL, do not apply 

within 150 feet of all aquatic areas. Do not 

use products with the same mode of action 

in consecutive applications.

Citrus fruits (crop group 10) west 

of the Mississippi River 0.20 0.40 B

Do not apply by air except in TX. Do not 

apply within 75 feet of fish-bearing waters. 

Do not use products with the same mode of 

action in consecutive applications. 

Cotton 0.10 0.10 B

Do not apply within 75 feet of fish-bearing 

waters. Do not use products with the same 

mode of action in consecutive applications.

Fruiting vegetables (crop group 8) 0.10 0.20 C

Grapes 0.10 0.10 Not stated B

Ground

Hops 0.15 0.15 B

Mint 0.10 0.20 B7

Nonbearing fruit trees, nut trees, 

and vines 0.10 0.10 B

Not stated

Ornamentals 0.10 0.10 B

Pome fruits (crop group 11) 0.10 0.10 B Not 

applicable
6

EPA 

Reg. No.

Active 

Ingredient (%) Use

Max. Single 

App. Rate

(lbs a.i./A)

Max. Annual 

App. Rate 

(lbs a.i./A)

App. 

Interval 

(d)

Application 

Type Additional Application Directions

Almonds and pistachios west of 

the Mississippi River 0.20 0.40 B

Tree nuts (crop group 14) 14

excluding almonds and pistachios, 

west of the Mississippi River

0.20 0.20 B

Tree nuts (crop group 14) east of 

the Mississippi River 0.10 0.10 B Not applicable

A The label vaguely provides a maximum product volume per crop cycle or growing season, whichever is longer. This is interpreted as an annual rate limit.

B The labeled application rate limit is given per growing season, which is interpreted as per year.

C The labeled application rate limit is given per crop cycle. These crops are not typically planted more than once per year in the same field (USEPA, 2007). 

Therefore, the application rate limits per crop cycle were used as annual rate limits.

D The low-growing berry crop subgroup (13-07G) includes cranberries.
7

3.2. Fate and Transport Characterization

Fenpyroximate [tert-butyl (E)-α-(1,3-dimethyl-5-phenoxypyrazol-4-

ylmethyleneaminooxy)-p-toluate; CAS# 134098-61-6] is a trans stereoisomer) and a tert-butyl

ester (chemical structure is in Appendix A). The compound is relatively nonvolatile, lipophilic, 

and slightly to hardly mobile in soil. Fenpyroximate degrades mainly via moderate 

biodegradation in soil and water bodies (half-lives of 23-41 days in aerobic and anaerobic 

systems). The compound is also rapidly photoisomerized to reach equilibrium with its cis isomer 

M-1 and photolyzed in shallow, illuminated water (fenpyroximate half-life of 1.5 hours; M-1 

half-life of 10.5 hours). However, the importance of this degradation pathway is expected to be 

limited because fenpyroximate and its isomer are expected to partition to sediment in water 

bodies, where aqueous photolysis is limited. Fenpyroximate does not hydrolyze readily and may 

bioconcentrate in fish. Fenpyroximate’s cis isomer M-1, its carboxylic acid M-3, and cleavage 

products M-6, M-8, M-11, M-16, and carbon dioxide are its major transformation products

(chemical names and structures are in Appendix A).

Fenpyroximate is not expected to move to ground water but may move to surface water 

bodies via spray drift and runoff of residues sorbed to suspended sediment. Table 3.2

summarizes the submitted chemical and environmental fate data for fenpyroximate.

Table 3.2. Chemical Properties and Environmental Fate Parameters of Fenpyroximate

Parameter Value Source

Selected Physical/Chemical Parameters

Molecular mass (molecular formula) 421.50 g/mol (C24H27N3O4) (Calculated)

Vapor pressure (25 °C) 5.6 x 10-8torr MRID 44781003

Aqueous solubility (25C) pH 5: 0.023 mg/L pH 7: 0.026 mg/L

pH 9: 0.034 mg/L

MRID 44781003

Henry’s Law Constant (25°C, pH 7) 1.2 x10-6atm-m

3

/mol (Calculated)

Log octanol-to-water partition coefficient

(log KOW)

5.01 MRID 44781003

Dissociation constant (pKb) Not determined MRID 44781003

Persistence

Hydrolysis half-life (25C) pH 5: 180 d pH 7: 226 d

pH 9: 221 d

MRID 44847909

Aqueous photolysis half-life (25C) 1.8 hrs (0.15 solar days) MRID 44781016

Soil photolysis half-life (25C) 24 d MRID 45649705

Aerobic soil metabolism half-life (25°C) 28, 41 d MRID 45187901/ 

45649706

39 d MRID 46158501

Anaerobic aquatic metabolism half-life 

(25C)

33 d MRID 45649707

Aerobic aquatic metabolism half-life (20C) 23, 34 d MRID 47521406
8

Parameter Value Source

Mobility

Freundlich soil-water partition coefficients 

(KF); Freundlich organic carbon-normalized 

coefficients (KFOC)

83, 93, 175, 290, 1,370 L/kg;

7,550, 18,600, 41,400, 44,000, 58,300 

L/kgOC

MRID 45649709

Field Dissipation

Terrestrial field dissipation half-life 1 d (German sandy silt loam),

11 d (German sandy loam),

12 (German loamy sand),

24 d (German sandy loam)

MRID 45649710/ 

45649711

3.6 d (Commerce silt loam, AR),

4.1 d (Cajon sandy loam, CA),

15 d (Norfolk sandy loam, NC)

MRID 45649712/ 

45734203

Fish Bioconcentration

Fish bioconcentration factors (steady-state, 

total residues)

770-1100 (edible), 2800-4100 

(inedible), 1800-2700 (whole fish)

MRID 48381102

3.2.1. Transport and Mobility

Fenpyroximate will not significantly volatilize despite having a low solubility in water 

(0.023-0.034 mg/L at pH 5-9, 25°C; MRID 44781003) and moderate Henry’s Law Constant (1.2

x 10-6atm-m

3

/mol) because of its low vapor pressure (5.6 x 10-8torr at 25°C; MRID 44781003) 

and high KOW of 100,000 (log KOW of 5.01; MRID 44781003). Minimal volatility was observed 

in the environmental fate studies because of high sorption to soil.

Fenpyroximate is slightly to hardly mobile in soil, with KFOC values of 7,550-58,300

L/kgOC (MRID 45649709). Sorption to soil correlates with the organic carbon fraction in soil

(i.e., the coefficient of variation across five soils for KFOC (60%) is less than that for KF (136%)). 

The compound is not expected to move to ground water via leaching but may be sorbed to 

suspended sediment in runoff feeding surface water bodies.

3.2.2. Degradation

Fenpyroximate slowly hydrolyzes at environmental pH values, with half-lives of 180-226 

days at pH 5-9 (MRID 44847909). In contrast, fenpyroximate is rapidly photoisomerized to 

reach equilibrium with its cis isomer, M-1, and photolyzed in water, with a half-life of 1.8 hours 

(MRID 44781016). The photolysis half-life of M-1 was 12 hours. M-11 was the predominant 

photoproduct of fenpyroximate and M-1. The importance of phototransformation is expected to 

be limited, however, because fenpyroximate and its isomer are expected to partition to sediment 

in water bodies, where aqueous photolysis is limited.

Fenpyroximate moderately degraded in aerobic soil with half-lives of 28, 39, and 41 days

(MRID 45187901/45649706, 46158501). M-3, M-8, and carbon dioxide were major degradates

in soil. In aerobic aquatic systems, the compound moderately degraded at similar rates, with 

half-lives of 23 and 34 days (MRID 47521406). M-3, M-8, and M-11 were major degradates in 
9

these systems. Under anaerobic aquatic conditions, fenpyroximate degraded at a similar rate, 

with a half-life of 33 days (MRID 45649707). M-3, M-8, M-11, and M-16 were the major 

degradates in anaerobic conditions.

3.2.3. Field Studies

Fenpyroximate dissipated under terrestrial field conditions with half-lives of 1-24 days 

(MRID 45649710/-11 and 45649712/45734203), based on the results of three bare ground field 

experiments conducted in the United States and four conducted in Germany. These field 

dissipation half-lives range from being shorter than to similar to laboratory-derived degradation 

half-lives in soil (28-41 days). At the U.S. sites, half-lives of fenpyroximate + M-1 + M-3 were 

35 days in the silt loam soil in Arkansas, 15 days in the sandy loam soil in California, and 43 

days in the sandy loam soil in North Carolina. Fenpyroximate plus M-1 was not detected below 

the 15-cm soil depth, and was not detected at any site after 61 days posttreatment. The soils 

were also analyzed for the transformation products M-3, M-8, and M-11. M-8 and M-11 were 

not detected at any of the sites. M-3 was detected in all three U.S. studies. At the German sites, 

fenpyroximate + M-1 + M-3 dissipated with half-lives of 3 to 37 days. Fenpyroximate was not 

detected below the 10-cm depth, except at one site at one sampling interval, and was not detected 

at any site after 56 days posttreatment.

3.2.4. Fish Bioconcentration

Fenpyroximate may bioaccumulate in aquatic organisms, with fish bioconcentration 

factors of up to 1100, 4100, and 2700 for edible, inedible, and whole fish tissues, respectively

(factors are uncertain due to high total organic carbon concentrations in the test systems; MRID 

48381102). Only one concentration of fenpyroximate was studied and degradation was not 

monitored in this study. Depuration half-lives for the edible, inedible, and whole fish tissues 

were 5.2-5.3 days. The respective depuration rate constant for whole fish (kT of 0.131 d-1) was

well above the sum of elimination constants estimated by KABAM (k2+kE+kG of 0.035 d

-1

), 

which indicates that the compound was metabolized in fish (KABAM neglects metabolism by

default). The KABAM-estimated BCF for fenpyroximate was 4900, which is higher than the 

study-derived values of 1800-2700 for whole fish. However, the KABAM-estimated BCF for 

fenpyroximate based on the contribution of fish concentrations due to respiration is reduced from 

3900 to 1100 when a metabolism rate constant (kM) for small to large fish of 0.096 d-1is used. 

This metabolism rate constant was calculated by subtracting the sum of elimination rate 

constants estimated by KABAM (k2 + kE +kG of 0.035 d-1) from the study-derived depuration 

rate constant (kT of 0.131 d-1). The BCF estimate of 1100 is lower than the study-derived BCF 

values of 1800-2700, which indicates that the calculated metabolism rate constant may be 

overestimated.

3.2.5. Environmental Degradates

Major identified environmental transformation products of fenpyroximate are its cis

isomer M-1, its carboxylic acid M-3, and cleavage products M-6, M-8, M-11, M-16, and carbon 

dioxide (chemical names and structures are in Appendix A). Figure A.1 of Appendix A 

illustrates the transformation pathway of fenpyroximate in the environment.
10

Major organic degradates of fenpyroximate (and M-1) tend to have higher mobility in 

soil than the parent compound (and its isomer). Mean KFOC values for M-3, M-8, and M-11 are 

660, 90, and 611 L/kgOC (n=4; MRID 45649708 and 47521401). As expected for a carboxylic 

acid, M-3 is orders of magnitude more soluble in water (solubility of ≥25 mg/L at 25°C; MRID 

45649708) than fenpyroximate.

3.2.6. Residues of Concern

The Metabolism Assessment Review Committee (MARC) of the Health Effects Division 

included as residues of concern in drinking water, fenpyroximate parent, its cis isomer M-1, and 

its carboxylic acid M-3 (USEPA, 2003). Due to the structural similarity of the compounds and 

the lack of toxicity data, they are assumed to have equivalent toxicity.

Drinking water exposure to the residues of concern is estimated using available chemical 

properties and environmental fate data. A total residues of concern (TRC) approach was used 

because the residues are assumed to have equivalent toxicity and degradation studies were not 

performed on M-3. Table 3.3 lists the environmental fate parameters for the fenpyroximate TRC

that are relevant for exposure modeling. Degradation half-lives reflect regression of the total 

residues at each study interval. Batch equilibrium data were available for M-3 (MRID 

45649708). Chemical properties of the parent compound were used to represent those of the 

residues of concern due to the lack of data on M-3.

Table 3.3. Environmental fate parameters of the total residues of concern

Parameter Value Source

Persistence

Hydrolysis half-life (25C) Stable (pH 5, 7, 9) MRID 44847909

Aqueous photolysis half-life (25C) 12 hrs (0.98 solar days) MRID 44781016

Aerobic soil metabolism half-life (25C) 31, 47 d MRID 45187901/ 

45649706

53 d MRID 46158501

Aerobic aquatic metabolism half-life (20C) 37, 44 d MRID 47521406

Anaerobic aquatic metabolism half-life (25C) 149 d MRID 45649707

Mobility

Range of Freundlich organic carbon normalized 

partition coefficients (KFOC)

Parent: 7,550-58,300 L/kgOC (n=5) MRID 45649709

M-3: 124-1,310 L/kgOC (n=4) MRID 45649708
11

3.3. Drinking Water Exposure Modeling

3.3.1. Models

3.3.1.1. FIRST

The FQPA Index Reservoir Screening Tool (FIRST v1.1.1, Mar. 25, 2008; USEPA, 

2008) is a Tier I screening model that simulates the upper-end exposure of the standard water 

body, the Index Reservoir, to pesticide residues in runoff and spray drift from an application 

within the standard watershed. Peak and annual mean EDWCs are generated to estimate acute 

and chronic exposure. The Index Reservoir covers 5.2 hectares (ha) with an average depth of 

2.74 meters (m) in a standard watershed of 172.8 ha. A more detailed description of the index 

reservoir watershed can be found in Jones et al., 2010. The FIRST model and user’s manual are 

available from the EPA Water Models web-page (USEPA, 2012).

3.3.1.2. Provisional Cranberry Model

The Provisional Cranberry Model is a provisional refinement to the Tier I Rice Model 

(v1.0, May 8, 2007). Refinements include the addition of simple degradation processes in dry

and flooded conditions and a water depth of twelve inches, rather than the water depth of four 

inches used in the rice model. These modifications allow estimation of screening-level peak and 

annual mean EDWCs of fenpyroximate residues of concern that may occur in untreated surface 

water used as drinking water following use on cranberries.

The Tier I Rice Model relies on an equilibrium partitioning concept to provide 

conservative estimates of EDWCs resulting from application of pesticides to rice paddies. When 

a pesticide is applied to a rice paddy, the model assumes that it will instantaneously partition 

between a water phase and a sediment phase. The model does not account for pesticide 

degradation, mass transfer between the aqueous phase and the sediment, volatilization, dilution, 

or other dissipation processes. The Tier I Rice Model was calibrated to generate estimates that 

are consistent with or conservative for dissolved concentrations measured within rice paddies 

and in discharged paddy water. The model was not evaluated or calibrated for concentrations 

measured in sediment and does not account for residues bound to suspended sediment. Guidance 

for using the Tier I Rice Model may be found on the U.S. Environmental Protection Agency

(EPA) Water Models web-page (USEPA, 2012). 

The Provisional Cranberry Model is based on the same assumptions as the Tier I Rice 

Model, with the addition of degradation processes in dry and flood conditions and a water depth 

of twelve inches in the flooded cranberry bog. Degradation of fenpyroximate residues of 

concern is assumed to occur predominantly via aerobic microbial metabolism, whether on dry

cranberry bog soil or in bog flood water.

The cranberry bog water depth of twelve inches is a maximum depth recommended by

the Cape Cod Cranberry Growers Association (2001). Previous assessments of mesotrione uses 

that employed the Provisional Cranberry Model assumed a water depth of eighteen inches (DP 

barcode 339984, USEPA, 2004; DP barcode 325840, USEPA, 2006a), which is within the range 
12

of water depths traditionally used. However, modern water conservation pressures are causing 

cranberry growers to reduce the flood depth to fewer inches above the vertical cranberry

branches, which grow up to eight inches high (Cape Cod Cranberry Growers Association, 2001; 

The Cranberry Institute, 2008). Therefore, a twelve-inch deep flood is a reasonable refinement 

to model assumptions. The equations used in the Provisional Cranberry Model are briefly 

described in Appendix C.

EDWCs generated with the Provisional Cranberry Model have not been evaluated. 

However, the Tier I Rice Model is expected to generate conservative EDWCs that exceed peak 

measured concentrations of pesticides in water bodies well downstream of rice paddies by less 

than one order of magnitude to multiple orders of magnitude.

3.3.1.3. SCI-GROW

Screening Concentration in Ground Water (SCI-GROW v2.3, Jul. 29, 2003; USEPA, 

2002) 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 studies. The RILP is a function of aerobic soil 

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

concentrations of pesticide residue that might be expected in shallow unconfined aquifers under 

sandy soils, which is representative of the ground water most vulnerable to pesticide 

contamination and likely to serve as a drinking water source. The SCI-GROW model and user’s 

manual is also available from the EPA Water Models web-page (USEPA, 2012). FIRST, the 

Provisional Cranberry Model, and SCI-GROW were used to estimate screening-level exposure 

of drinking water sources to total residues of concern of fenpyroximate.

3.3.2. Input Parameters

3.3.2.1. FIRST

Input parameters for FIRST follow in Table 3.4. The modeled use pattern represents the 

current or proposed use pattern of highest estimated exposure, which is the current use on 

ornamentals (two aerial applications per year at 0.343 lbs a.i./acre). A reapplication interval for 

use on ornamentals is not stated on the label; however, the label prohibits consecutive 

applications of products with the same mode of action. Therefore, a reapplication interval of 6 

days was modeled, assuming that treatments may be necessary every 3 days, with an alternative 

chemistry applied between applications of fenpyroximate.

Table 3.4. FIRST input parameters for total residues of fenpyroximate A

Input Parameter Value Comments Source

Application rate (lbs a.i./A) 0.343 Maximum proposed single application 

rate

EPA Reg. No. 

71711-4

Number of applications per 

year

2

Number of applications at the 

maximum application rate that achieves 

the maximum rate per growing season.

EPA Reg. No. 

71711-4
13

Input Parameter Value Comments Source

Application interval (d) 6

Assumed in the absence of label 

directions (see text for discussion).

EPA Reg. No. 

71711-4

Percent cropped area 87% Default agricultural PCA Jones et al., 2010a

Organic carbon partition 

coefficient (KOC) (L/kgOC)

Parent: 34,000

M-3: 649

Represents the mean KFOC values for 

parent (n=5) and M-3 (n=5).

MRID 45649708, 

45649709

Aerobic soil metabolism 

half-life (days) 56

Represents the upper 90% confidence 

bound on the mean of three half-lives 

for the residues of concern.

MRID 45187901/ 

45649706, 

46158501

Wetted in? No Not required. EPA Reg. No. 

71711-4

Method of application Aerial

Application method assumed in the 

absence of label directions for 

ornamentals.

EPA Reg. No. 

71711-4

Solubility in water (ppm) Parent: 0.026

M-3: 25

Upper limit for parent and lower limit 

for M-3in pH 7 water.

MRID 44781003, 

45649708

Aerobic aquatic metabolism

half-life (days) 51

Represents the upper 90% confidence 

bound on the mean of two half-lives for 

the residues of concern.

MRID 47521406

Aqueous photolysis half-life 

(days) 0.975 Represents the maximum half-life for the residues of concern.

MRID 44781016

A

 Source data are in Tables 3.1-3.3.

Chemical property input values were chosen in accordance with current input parameter 

guidance (USEPA, 2009). Based on analysis of total residues of concern, the 90% confidence 

bound on the mean half-life for aerobic soil metabolism (56 d) and for aerobic aquatic 

metabolism (51 d) were selected. Water solubility limits and KOC inputs representing the mean 

values for the parent compound (n=5) and for M-3 (n=5) were modeled separately to bracket the 

potential exposure to residues of concern, representing cases of 1) no M-3 formation and 2) 

complete conversion of residues to M-3, which is more soluble in water and more mobile in soil 

than fenpyroximate and M-1.

Standard percent cropped areas (PCA) are used as conservative default estimates of the 

extent of watershed on which agricultural crops of unknown specific PCA are grown (Jones et 

al., 2010a). For this screening assessment, the default national PCA value of 87% was used to 

adjust exposure estimates because fenpyroximate is labeled for use on a variety of agricultural 

crops as well as ornamentals, many of which are agricultural, such as nonbearing fruit trees and 

vines.

3.3.2.2. Provisional Cranberry Model

The current use of fenpyroximate on cranberries at the maximum proposed application 

rate (0.10 lbs a.i./acre) may occur no more than two times per year, resulting in an annual 

application rate limit of 0.20 lbs a.i./acre (EPA Reg. No. 71711-19). The minimum reapplication 

interval of 14 days stated on the proposed label was modeled; however, this limitation is not on 

the current label. If this reapplication interval is not implemented, then exposure should be 

reanalyzed assuming a shorter reapplication interval.
14

Cranberry bogs are often flooded on the night before harvesting. EPA Reg. No. 71711-

19 states not to apply fenpyroximate to cranberries within 1 day of harvest. Therefore, the single 

application rate (0.10 lbs a.i./acre) was aged on dry soil with the Provisional Cranberry Model 

for two durations that are 14 days apart: 16 and 2 days. The resulting residues (in lbs a.i./acre) 

were summed together for each residue and input into the flooded component of the model to 

estimate exposure in bog tailwater following harvest. Peak and annual mean EDWCs were 

calculated beginning three days after flooding to account for transport time to a down-gradient 

drinking water intake following release of bog tailwater not long after flooding. Chemical 

property input values were calculated for modeling as was done for FIRST. Model input 

parameters are listed in Table 3.5. As stated above, the default national PCA value of 87% was 

used to adjust exposure estimates in this assessment.

Table 3.5. Provisional Cranberry Model input parameters for total residues of 

fenpyroximate A

Input Parameter Value Comments Source

Application rate

(lbs a.i./A) 0.10 Maximum proposed single application rate

EPA Reg. No. 

71711-19

Applications per year 2

Maximum number of applications per 

year at the maximum single 

application rate

EPA Reg. No. 

71711-19

Application-to-harvest 

intervals (d) 2, 16

Intervals between applications and 

harvest are discussed in the text 

above.

EPA Reg. No. 

71711-19

Organic carbon partition 

coefficient (KOC) (L/kgOC)

Parent: 34,000

M-3: 649

Represents the mean KFOC values for 

parent (n=5) and M-3 (n=5).

MRID 45649708, 

45649709

Aerobic soil metabolism 

half-life (days) 56

Represents the upper 90% confidence 

bound on the mean of three half-lives 

for the residues of concern.

MRID 45187901/ 

45649706, 

46158501

Aerobic aquatic 

metabolism

half-life (days)

51

Represents the upper 90% confidence 

bound on the mean of two half-lives 

for the residues of concern.

MRID 47521406

A

 Source data are in Tables 3.1-3.3.

3.3.2.3. SCI-GROW

Input parameters for the SCI-GROW model appear in Table 3.6. The lowest Freundlich

organic carbon partition coefficients for fenpyroximate (KFOC = 7550 L/kgOC) and M-3 (KFOC = 

124 L/kgOC) were selected to bracket exposure between residues of undegraded fenpyroximate 

and its isomer and residues of the carboxylic acid M-3 (as was explained for modeling with 

FIRST). The mean total residue half-life (44 d) from three aerobic soils was selected to 

approximate the biodegradation kinetics of the residues of concern in aerobic soil environments.
15

Table 3.6. SCI-GROW input parameters for total residues of fenpyroximate.

A

Input Parameter Value Comments Source

Application rate (lbs a.i./A) 0.343 Maximum proposed single application 

rate

EPA Reg. No. 

71711-4

Number of applications per 

year

2

Number of applications at the maximum 

application rate that achieves the 

maximum rate per growing season.

EPA Reg. No. 

71711-4

Organic carbon partition 

coefficient (KOC) (L/kgOC)

Parent: 7,550

M-3: 124

Represent the lowest KFOC values, due 

to greater than 3-fold variation.

MRID 45649708, 

45649709

Aerobic soil metabolism 

half-life (days) 44 Represents the mean of three half-lives for the residues of concern.

MRID 45187901/ 

45649706, 

46158501

A

 Source data are in Tables 3.1-3.3.

3.3.3. Modeling Results

Screening estimates generated for drinking water exposure assessment are listed in Table 

3.7. The current use on ornamentals was the use resulting in maximum surface water and ground

water exposure using the FIRST and SCI-GROW models, as described above. The current use 

on low growing berries was the use of maximum surface water exposure using the Provisional 

Cranberry Model. Modeled estimates are peak and annual mean values for total residues, using a 

KOC input for either fenpyroximate parent or M-3, assuming complete conversion. Model 

input/output data and filenames for these estimates are attached in Appendix B.

Table 3.7. Maximum Drinking Water Exposure Estimates for the Current and Proposed 

Uses of Fenpyroximate.

A

Source (Tier: Model) KOC input 

(L/kgOC)

Peak Exposure 

(μg/L) B

Annual Mean 

Exposure (μg/L) B

Surface water (Tier I: FIRST)

Parent: 34,000 11 0.38

M-3: 649 29 1.9

Surface water (Tier I: Cranberry 

model)

Parent: 34,000 3.6 0.72

M-3: 649 43 8.6

Ground water (Tier I: SCI-GROW)

Parent: 7,550 ≤0.005

M-3: 124 ≤0.27

A

 Maximum values per model are in bold.

B

 Surface water concentrations calculated by FIRST are 1-in-10-year values. Ground water concentrations 

calculated by SCI-GROW are the highest 90-day running average.

Exposure estimates for M-3 were substantially higher than those for the parent 

compound. In surface water, the maximum exposure estimates for M-3 following use on 

cranberries were a peak of 43 μg/L and an annual average of 8.6 μg/L. Maximum exposure 

estimates for M-3 following use on ornamentals were lower, with a 1-in-10-year peak of 29 μg/L

and a 1-in-10-year annual average of 1.9 μg/L. The Tier I screening EDWC for M-3 in ground 

water was 0.27 μg/L.
16

3.3.4. Drinking Water Treatment

The Office of Pesticide Programs (OPP) does not have direct data on the effects of 

drinking water treatment on fenpyroximate. Flocculation and sedimentation removal may be 

effective at reducing fenpyroximate concentrations. Carbon filtering is also likely to reduce 

fenpyroximate concentrations due to the compound’s affinity to organic carbon. 

Carbon filtering may be less effective at reducing M-3 concentrations, however. Because of the 

absence of data on fenpyroximate and M-3, the effects of drinking water treatment were not 

considered in this assessment.

3.4. Fish Exposure

A screening estimate of fenpyroximate residues of concern in potentially humanconsumed fish was generated using the KOW (based) Aquatic BioAccumulation Model (KABAM 

v.1.0) and the Provisional Cranberry Model. 

Provisional Cranberry Model inputs are as listed in Table 3.5 for drinking water exposure 

modeling, with the KOC input of 34,000 L/kgOC for the parent compound (and M-1). M-3 was 

included as a residue of concern in fish because its log KOW value (4.25) estimated by EpiSUITE 

(v4.1) is greater than three. Whether it is included as a residue of concern does not substantially

change fish concentrations. The cranberry model output was 3.4 μg/L, which is the 30-day mean 

water concentration beginning 3 days after bog flooding. A 30-day mean concentration was used 

because the 30 days is the time to steady-state estimated by KABAM. A 3-day period between 

flooding and release of bog water was assumed to occur to allow for harvesting.

KABAM was used to estimate screening concentrations of fenpyroximate residues of 

concern in large fish. The bioaccumulation portion of KABAM is based on an aquatic food web 

bioaccumulation model published by Arnot and Gobas (2004) that relies on a pesticide's octanolwater partition coefficient (KOW) to estimate uptake and elimination constants through 

respiration and diet of aquatic organisms in different trophic levels. Pesticide tissue 

concentrations in aquatic organisms are calculated for different trophic levels of a food web 

through diet and respiration. The KABAM model and user’s manual are available from the EPA 

Water Models web-page (USEPA, 2012).

KABAM was run in default mode (see user’s guide for full description), with a log KOW

of 5.01, a KOC of 34,000 L/kgOC, a metabolism rate constant (kM) for small to large fish of 0.096 

d

-1

, a study-derived water temperature of 22°C, and the single surface water and pore water 30-

day mean concentration of 3.4 μg/L, which was generated with the Provisional Cranberry Model. 

The metabolism rate constant was calculated by subtracting the sum of elimination rate constants 

estimated by KABAM (k2 + kE +kG of 0.035 d-1) from the study-derived depuration rate constant 

(kT of 0.131 d-1). This was done because KABAM does not account for metabolism by default. 

The resulting fenpyroximate residues concentration in large fish was 7.1 mg/kg-bw (ww).

If fenpyroximate residues were to completely convert to M-3 in the environment, the 

residue concentration in large fish would be estimated at 30 mg/kg-bw (ww). This is the result 

of entering the KOC input of 649 L/kgOC for M-3 into the Provisional Cranberry Model and 
17

KABAM and entering the resulting 7-day mean concentration in cranberry bog water (47 μg/L) 

and the EpiSUITE-estimated log KOW value of 4.25 into KABAM, leaving all other input values 

for the modeling of fenpyroximate unchanged. However, complete conversion to M-3 is 

unlikely in the environment because M-3 only formed up to 15% and 25% of the applied in the 

submitted soil biodegradation (MRIDs 45649706 and 46158501) and aquatic biodegradation 

(MRID 47521406) studies, respectively.

These screening estimates represent high-end concentrations in fish that may occur 

following release of cranberry bog water into a stagnant fish-bearing water body. Dissipation 

processes such as dilution, flow downstream, and partitioning to water body sediment were 

neglected. If these screening concentrations in fish result in risk concerns, then exposure 

assessment refinements are needed (the concentrations do not necessarily reflect actual exposure 

that may occur or may have occurred).

4. CONCLUSIONS

Screening drinking water exposure estimates for proposed fenpyroximate uses on snap 

beans and tropical fruits including avocado and an outdoor use on cucumbers are represented by 

the maximum use patterns on cranberries and ornamentals (Tables 1.1 and 3.7). The total 

residues of concern of fenpyroximate include fenpyroximate parent, its cis isomer M-1, and its 

carboxylic acid M-3, all of which are assumed to have similar toxicity. Maximum screening Tier 

I exposure estimates in ground water (0.27 μg/L) are two orders of magnitude less than those in

surface water (29-43 μg/L). The maximum screening exposure estimate in fish that may be 

consumed by humans is 30 mg/kg-bw (ww).

5. LITERATURE CITATIONS

Arnot, J.A. and F.A.P.C. Gobas. 2004. A food web bioaccumulation model for organic chemicals in aquatic 

ecosystems. Environmental Toxicology and Chemistry, 23 (10): 2343-2355

Cape Cod Cranberry Growers Association. 2001. Cranberry Water Use: An Information Fact Sheet. June, 2001. 

Online at: http://www.cranberries.org/pdf/wateruse.pdf. Accessed Jan. 10, 2012.

Jones, R. D., K. Costello, J. Hetrick, J. Lin, R. Parker, N. Thurman, C. Peck. 2010. Development and Use of the 

Index Reservoir in Drinking Water Exposure Assessments. U.S. Environmental Protection Agency, Office 

of Pesticide Programs. April 15, 2010. Online at: 

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

Jones, R. D., K. Costello, J. Hetrick, J. Lin, R. Parker, N. Thurman, C. Peck, G. Orrick. 2010a. Development and 

Use of Percent Cropped Area Adjustment Factors in Drinking Water Exposure Assessments. U.S. 

Environmental Protection Agency, Office of Pesticide Programs. September 9, 2010. Online at: 

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

The Cranberry Institute. 2010. About Cranberries. 2003-2010. Online at: 

http://www.cranberryinstitute.org/about_cranberry.htm. Accessed Jan. 10, 2012.

United States Environmental Protection Agency (USEPA). 2002. SCI-GROW User’s Manual. U.S. Environmental

Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects Division. Nov. 1, 2001; 

revised Aug. 23, 2002.
18

USEPA. 2003. Stokes, J. Fenpyroximate: Conclusion and Briefing Memorandum for 07/09/03 Meeting of the 

Health Effects Division (HED) Metabolism Assessment Review Committee (MARC). DP barcode 

292639. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, 

Health Effects Division. Internal memorandum. Aug. 12, 2003.

USEPA. 2008. FIRST User’s Manual. Version 1.1.1. U.S. Environmental Protection Agency, Office of Pesticide 

Programs, Environmental Fate and Effects Division. Mar. 26, 2008.

USEPA. 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. Online at: 

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

USEPA. 2012. Water Models. U.S. Environmental Protection Agency, Pesticides: Science and Policy, Models and 

Databases. Last updated Jan. 10, 2012. Online at: http://www.epa.gov/oppefed1/models/water/

5.1.Submitted Environmental Fate Studies

MRID Citation Reference

44781003 Todhunter, J.; Hill, J. (1999) Fenpyroximate--Technical Active Ingredient (TGAI) and Fenpyroximate 

5% SC (End Use Product): Product Chemistry, Series 63: Lab Project Number: NNI-FENPY-99-003. 

Unpublished study prepared by SRS International Corporation. 19 p. 

44781016 Swanson, M. (1993) Direct Photolysis of Pyrazole-(carbon-14)-Fenpyroximate in a Buffered Aqueous 

Solution Under Artificial Sunlight: Final Report: Lab Project Number: SC910077: SC910089: E-4015. 

Unpublished study prepared by Battelle Memorial Institute. 126 p. 

44847909 Saxena, A.; McCann, D. (1992) Hydrolysis of Pyrazole- (carbon-14)-Fenpyroximate in Buffered 

Aqueous Solutions: Final Report: Lab Project Number: SC900192. Unpublished study prepared by 

Battelle Memorial Institute. 97 p. 

44847910 Rombke, J.; Brodesser, J. (1992) Determination of the Degradation in Soil of Fenpyroximate: Final 

Report: Lab Project Number: E-4020: BE-ME-107-90-01SAB1. Unpublished study prepared by Battelle 

Europe. 46 p. 

44847911 McCann, D. (1992) Sorption/Desorption of Pyrazole- (carbon-14)-Fenpyroximate on Soils by the Batch 

Equilibrium Method: Final Report: Lab Project Number: SC9101024. Unpublished study prepared by 

Battelle Memorial Institute. 124 p. 

45187901 Funayama, S.; Atsuko, H.; Izawa, Y. (1990) Degradation of (Pyrazole-14C) and (Benzyl-14C) 

Fenpyroximate in Soils Under Laboratory Conditions: Lab Project Number: E-4005. Unpublished study 

prepared by Nihon Nohyaku Co., Ltd. 52 p. 

45649705 Concha, M. (2001) Photodegradation of (Carbon-14) Fenpyroximate in/on Soil by Artificial Light: Lab 

Project Number: E-4030: 870W-1: 870W. Unpublished study prepared by PTRL West, Inc. 188 p. 

45649706 Maks, M. (2002) Degradation of Pyrazole-(Carbon-14) and Benzyl-(Carbon-14) Fenpyroximate in Soils 

Under Laboratory Conditions: Lab Project Number: E-4005. Unpublished study prepared by Nichino 

America, Inc. 8 p. 

45649707 McKemie, T.; Shepler, K. (2001) Anaerobic Aquatic Metabolism of (Carbon 14) Fenpyroximate: Lab 

Project Number: 889W-1: 889W: E-4031. Unpublished study prepared by PTRL West, Inc. 232 p. 

45649708 Concha, M. (2002) Soil Adsorption/Desorption of (Carbon 14) M-3 by the Batch Equilibrium Method: 

Lab Project Number: 1045W. Unpublished study prepared by PTRL West, Inc. 132 p. 

45649709 Concha, M. (2002) Soil Adsorption/Desorption of (Carbon 14) Fenpyroximate by the Batch Equilibrium 

Method: Lab Project Number: 987W: E-4033. Unpublished study prepared by PTRL West, Inc. 151 p. 
19

MRID Citation Reference

45649710 Burstell, H.; Sochor, H. (1994) Fenpyroximate Water Miscible Suspension 50g/l: Investigation of the 

Degradation Behaviour in Soil Under Field Conditions: Lab Project Number: E-4028: ER91DEU824: 

A53773. Unpublished study prepared by Hoechst Schering AgrEvo GmbH. 55 p. 

45649711 Specht, W. (1993) Determination of the Residues of Fenpyroximate (HOE 094552), M-1 (HOE 112573) 

and M-3 (HOE 112721) in Soil: Lab Project Number: HOE-9107: 93615/91: A53773. Unpublished 

study prepared by Chemische Laboratorien GMBH. 146 p. 

45649712 Baker, F.; Mickelson, K.; Hiler, R. (2001) Field Soil Dissipation of Fenpyroximate in Bare Ground in 

North Carolina, Arkansas, and California: Lab Project Number: 803W-1: 803W: E-4032. Unpublished 

study prepared by Research for Hire. 253 p. 

45734203 Hiler, R. (2002) Quantification of Metabolites M-3, M-8, and M-11 in Soil from Field Soil Dissipation 

of Fenpyroximate in Bare Ground in North Carolina, Arkansas and California: Lab Project Number: E4038: 1026W: 1026W-1. Unpublished study prepared by Research for Hire. 855 p. 

46158501 Shepler, K. (2003) Aerobic Soil Metabolism of (Carbon 14) Fenpyroximate. Project Number: 1038W. 

Unpublished study prepared by PTRL West, Inc. 160 p.

47521401 Hiler, T. (2008) Soil Adsorption/Desorption of M-8 and M-11 by the Batch Equilibrium Method. Project 

Number: 1705W, 1705W/1. Unpublished study prepared by PTRL West, Inc. 269 p.

47521406 Volkl, D. (2001) (Carbon-14) Fenpyroximate (NNI-850) [Pyrazole-labelled] Degradation and 

Metabolism in Aquatic Systems. Project Number: E/4027/SUPP/1, 7L365. Unpublished study prepared 

by RCC Ltd. 134 p.

48381102 Thomas, S.; Kendall, T.; Krueger, H. (2010) Fenpyroximate: A Bioconcentration Test with the Bluegill 

(Lepomis macrochirus): Final Report. Project Number: 397A/140. Unpublished study prepared by 

Wildlife International, Ltd. 93 p.
20

Appendix A. Chemical Names and Structures of Fenpyroximate and Its Transformation Products

Table A.1. Fenpyroximate and Its Environmental Transformation Products

Code Name/ 

Synonym

Chemical Name Chemical Structure

PARENT

Fenpyroximate 

(E-isomer)

IUPAC: tert-butyl (E)-α-(1,3-dimethyl-5-phenoxypyrazol4-ylmethyleneaminooxy)-p-toluate

CAS: 1,1-dimethylethyl 4-[[[(E)-[(1,3-dimethyl-5-

phenoxy-1H-pyrazol-4-

yl)methylene]amino]oxy]methyl]benzoate

CAS No.: 134098-61-6

Formula: C24H27N3O4

MW: 421.50 g/mol

MAJOR TRANSFORMATION PRODUCTS

M-1

(Z-isomer)

tert-butyl (Z)-4-[(1,3-dimethyl-5-phenoxypyrazol-4-

yl)methylene-aminooxymethyl]-benzoate

Formula: C24H27N3O4

MW: 421.50 g/mol
21

Code Name/ 

Synonym

Chemical Name Chemical Structure

M-3 (E)-4-[(1,3-dimethyl-5-phenoxypyrazol-4-yl)methyleneaminooxy-methyl]-benzoic acid

O H

O

C

H2

H O

H3C

N

C H3

O N

N

M-6 1,3-dimethyl-5-phenoxypyrazole-4-carbaldehyde
22

Code Name/ 

Synonym

Chemical Name Chemical Structure

M-8 1,3-dimethyl-5-phenoxypyrazole-4-carboxylic acid

M-11 1,3-dimethyl-5-phenoxypyrazole-4-carbonitrile

M-16 4-hydroxymethylbenzoic acid

Carbon dioxide Carbon dioxide

Formula: CO2

MW: 44.1 g/mol

O O
23

Figure A.1. Environmental Transformation Route of Fenpyroximate (MRID 45187901, p 52).
24

Appendix B. Model Input/Output Files

Fenpyroximate_1-10

-12.fir

Fenpyroximate 

1-11-12.sci

Input/Output Data for Individual Simulations

FIRST Input/Output File

 RUN No. 1 FOR Fenpyroximate ON Ornamental * INPUT VALUES * 

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

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

 ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)

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

 0.343( 0.661) 2 6 649.0 25.0 AERIAL(16.0) 87.0 0.0

 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

 (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.) 

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

 56.00 2 0.00 0.98- 120.90 51.00 35.87

 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1 MAR 26, 2008

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

 PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) 

 CONCENTRATION CONCENTRATION 

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

 29.355 1.909

 RUN No. 2 FOR Fenpyroximate ON Ornamental * INPUT VALUES * 

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

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

 ONE(MULT) INTERVAL Koc (PPB ) (%DRIFT) AREA (IN)

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

 0.343( 0.661) 2 6 34000.0 26.0 AERIAL(16.0) 87.0 0.0

 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

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

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

 (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.) 

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

 56.00 2 N/A 0.98- 120.90 51.00 35.87

 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1 MAR 26, 2008

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

 PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) 

 CONCENTRATION CONCENTRATION 

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

 10.756 0.375
25

SCI-GROW Input/Output File

SciGrow version 2.3

chemical:Fenpyroximate

time is 1/11/2012 10:27:46

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

 Application Number of Total Use Koc Soil Aerobic

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

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

 0.343 2.0 0.686 7.55E+03 44.0

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

groundwater screening cond (ppb) = 5.17E-03 

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

SciGrow version 2.3

chemical:Fenpyroximate

time is 1/11/2012 10:28:35

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

 Application Number of Total Use Koc Soil Aerobic

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

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

 0.343 2.0 0.686 1.24E+02 44.0

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

groundwater screening cond (ppb) = 2.69E-01 

************************************************************************
26

Appendix C. Provisional Cranberry Model Equations

The Provisional Cranberry Model is a refinement of the Tier I Rice Model v1.0 

(Equations 1 and 2), which is a simple equilibrium partitioning equation that calculates a single, 

screening-level concentration in rice paddy water and released tailwater based on a compound’s 

application rate and soil mobility.

Equations 1-2: Tier I Rice Model v1.0 (USEPA, 2007b).

  w sed sed b d

ai

w

d d K

m

C

 

3

2

0

10

10 '



 

 (1)

and, if appropriate:

Kd 01KOC  0. (2)

where,

Cw0 = initial water concentration [μg/L]

mai' = mass applied per unit area [kg/ha]

Kd = water-sediment partitioning coefficient [L/kg]

KOC = organic carbon partitioning coefficient [L/kg]

dw = water column depth = 0.10 m

dsed = sediment depth = 0.01 m

θsed = porosity of sediment = 0.509

ρb = bulk density of sediment = 1300 kg/m3

First, the Tier I Rice Model was provisionally modified (Equation 3) to include as inputs 

degradation rate constants in order to estimate single, screening-level concentrations in paddy 

water or tailwater at a given time after application.

Equation 3: Provisional Modified Rice Model (Jones, 2006).

d

kt

ai

w

K

m e

C

0.00105 0.00013

'







(3)

where,

Cw = water concentration [μg/L]

t = interval since last application [d]

k = upper 90th percentile degradation rate constant [1/d]
27

Then, the Provisional Modified Rice Model water column depth was lengthened to a 

depth that is used to flood cranberry bogs (i.e., 12 inches; Cape Cod Cranberry Growers 

Association, 2001).

i.e.,

dw = water column depth = 0.305 m

In order to model degradation prior to the flood at harvest, the application rates for n 

number of pre-harvest applications were independently degraded over the interim until flooding 

and then summed (Equation 4).

Equation 4: Degradation in a Dry Bog.





 

n

k t

ai ai n

n m m e

1

2

' ' (4)

where,

mai' = mass per unit area at flood [kg/ha]

mai'n = mass applied per unit area on the nth application [kg/ha]

k2 = upper 90th percentile degradation rate constant on dry bog [1/d]

tn = interval from the nth application to harvest [d]

n = number of pre-harvest applications

These four equations and parameter sets constitute the Provisional Cranberry Model 

(reorganized below as Equations 4, 5, and 2 plus parameters).
28

Equations 2, 4, and 5: Provisional Cranberry Model.





 

n

k t

ai ai n

n m m e

1

2

' ' (4)

where,

mai' = mass per unit area at flood [kg/ha]

mai'n = mass applied per unit area on the nth application [kg/ha]

k2 = upper 90th percentile degradation rate constant on dry bog [1/d]

tn = interval from the nth application to harvest [d]

n = number of pre-harvest applications

followed by:

  w sed sed b d

kt

ai

w

d d K

m e

C

 

3

2

10

10 '





 

 (5)

and, if appropriate:

Kd 01KOC  0. (2)

where,

Cw = water concentration [μg/L]

t = interval since flood [d]

k = upper 90th percentile degradation rate constant [1/d]

Kd = water-sediment partitioning coefficient [L/kg]

KOC = organic carbon partitioning coefficient [L/kg]

dw = water column depth = 0.305 m

dsed = sediment depth = 0.01 m

θsed = porosity of sediment = 0.509

ρb = bulk density of sediment = 1300 kg/m3